Genetic Signature Predicts Outcome Of Pediatric Liver Cancer

identified a genetic signature that is remarkably effective at predicting the prognosis of an aggressive liver cancer in children. The research, published by Cell Press in the December issue of the journal Cancer Cell, may lead to better treatments for pediatric liver cancers.

Hepatoblastoma (HB), the most common liver cancer in children, is associated with abnormal activation of the Wnt/beta-catenin signaling pathway. Although the specific details are not clear, Wnt signaling is essential for normal liver development. HB tumors can be comprised of cells that resemble fetal cells or immature progenitor cells but the cellular make-up of the tumor is frequently heterogeneous, precluding its systematic use for guiding treatment or predicting outcome.

"At present, few studies have addressed whether intrinsic biological differences between tumors impact HB prognosis. Moreover, new treatments are urgently needed for advanced stage tumors, and better understanding of HB pathobiology is a prerequisite for developing targeted therapies," explains senior study author Dr. Marie-Annick Buendia from the Oncogenesis and Molecular Virology Unit at the Pasteur Institute and Inserm Unit in Paris, France.

Dr. Buendia and colleagues used a sophisticated genetic screening technique to investigate the pathogenesis of HB. They found that beta-catenin was linked with two distinct tumor subclasses that reflect early and late phases of prenatal liver development. Further, they discovered a specific genetic signature that was useful for identifying the two tumor subclasses and predicting disease outcome.

The researchers also demonstrated that the highly proliferating, early stage tumors had characteristics associated with stem cells. Activation of Myc, a stem cell marker that is commonly overexpressed in cancer, appeared to play a key role in this tumor subtype. Further, activation of Myc in mice induced tumors that were strikingly similar to the human immature subtype of HB and inhibition of Myc in HB cells impaired tumorigenesis.

"We demonstrate that hepatic differentiation stage and clinical behavior of HB are intimately linked, and we identify an expression signature with dual capacities in recognizing liver developmental stage and predicting disease outcome. These data can be applied to improve clinical management of pediatric liver cancer and develop therapeutic strategies," concludes Dr. Buendia.

Molecular Marker Identifies Normal Stem Cells As Intestinal Tumor Source

Jude Children's Research Hospital have answered a central question in cancer biology: whether normal stem cells can give rise to tumors. Stem cells are immature cells that can renew themselves and give rise to mature differentiated cells that compose the range of body tissues. In recent years, researchers have developed evidence that cancers may arise from mutant forms of stem cells.

Tumor Suppressor Gene: Gene Function 'Lost' In Melanoma And Glioblastoma

Georgetown University Medical Center have found a gene they say is inactivated in two aggressive cancers – malignant melanoma, a form of skin cancer, and glioblastoma multiforme, a lethal brain tumor. They add that because this gene, known as PTPRD, has recently been found to be inactivated in several other cancers as well, their discovery suggests that PTPRD may play a tumor suppressor role in a wide variety of different cancers.Over the past decade several dozen tumor suppressor genes have been identified, but only a minority of them is important in causing many different tumor types. PTPRD seems to be one of these broad spectrum tumor suppressor genes," says the study's lead investigator, Todd Waldman, MD, PhD, an associate professor of oncology at Georgetown's Lombardi Comprehensive Cancer Center.

If the hypothesis is true – and Waldman and his team are now investigating loss of PTPRD in a number of additional cancers – then it may be possible to design a therapy that has wide applicability in oncology, he says.

"Most targeted cancer drugs today work by inhibiting gene products that are overactive in cancer cells. In this case, it is loss of the PTPRD gene that leads to cancer," Waldman says. "Therefore, we are trying to discover the molecules that PTPRD's protein controls, and then we plan to target these downstream molecules with a novel agent."

Waldman found that when the researchers restored production of the gene's protein in cancer cells that harbored PTPRD deletions or mutations, these tumors stopped growing and initiated a program of cell suicide.

The researchers also discovered PTPRD mutations in both the blood and in tumors of a patient with multiple different kinds of cancers. "This suggests that the gene could be responsible for an inherited predisposition to cancer," Waldman says

PTPRD produces a receptor protein tyrosine phosphatase that bisects the outer membrane of a cell. The part that protrudes outside the cell body is thought to be involved in helping cells stick to each other to form a tissue as well as in cell-to-cell communication. The part that juts into the cell is an enzyme that removes phosphates from other proteins – in other words, it changes the activity of proteins either by activating or deactivating them, Waldman says.

"In the absence of PTPRD, there are as yet unknown proteins floating around inside the cell with more phosphate residues than they should have, and it is a well known fact that the presence of these residues activates cellular growth pathways," he says. But it is not yet known which specific proteins PTPRD regulates, Waldman says.

Deletions of PTPRD in human cancer cells were first discovered in 2005, and since then, deletions or mutations of the gene have been discovered in several cancer types, including those of the colon and lung.

In this study, Waldman and his research team, which includes investigators from the National Cancer Institute, the University of Iowa and Duke University, used a laboratory technique known as copy number analysis to look for PTPRD in melanoma cell lines and in samples of human glioblastoma multiforme, the deadliest of brain cancers.

This technique uses a gene microarray that contains millions of probes that can stick to different regions of the human genome. The researchers purified DNA from tumors and then used the microarray chip to quantify genomic copy number. They found that PTPRD was deleted or mutated in 12 percent of melanoma tumors and in 14 percent of glioblastoma tumors examined. "That makes PTPRD one of the most commonly mutated genes discovered yet in melanoma," Waldman says.

"Before this study, no single tyrosine phosphatase was thought to play a generally important role as a tumor suppressor gene n multiple tumor types," Waldman says. "Now we have provided the first functional evidence that PTPRD is a tumor suppressor gene, and potentially an important one at that."

The findings are published in the December 15 issue of Cancer Research.

Molecule That Targets Brain Tumors Identified

Center researchers report today the discovery of a molecule that targets glioblastoma, a highly deadly form of cancer. The finding, which is published in the January 2009 issue of the European Journal of Nuclear Medicine and Molecular Imaging, provides hope for effectively treating an incurable cancer.

Glioblastoma is the most common and aggressive type of primary brain tumor in adults. It is marked by tumors with irregular shapes and poorly defined borders that rapidly invade neighboring tissues, making them difficult to remove surgically.

"These brain tumors are currently treated with surgery to remove as much of the tumor as possible followed by radiation to kill cancer cells left behind and systemic chemotherapy to prevent spread to nearby tissues," said Kit Lam, senior author of the study and UC Davis chief of hematology and oncology. "It is unfortunate that this approach does not extend survival significantly. Most patients survive less than one year."

To find new options for treating the disease, Lam and his colleagues began searching for a molecule that could be injected into a patient's bloodstream and deliver high concentrations of medication or radionuclides directly to brain tumor cells while sparing normal tissues. Through their study, they identified a molecule — called LXY1 — that binds with high specificity to a particular cell-surface protein called alpha-3 integrin, which is overexpressed on cancer cells.

They also tested the molecule's ability to target brain cancer by implanting human glioblastoma cells both beneath the skin and in the brains of mice. The researchers injected the mice with a radiolabeled version of LXY1 and, using near-infrared fluorescence imaging, showed that the molecule did preferentially bind to human glioblastoma cells in both locations.

"This outcome gives us great hope that we will be able to deliver targeted therapies to treat glioblastoma," said Lam.

Lam is planning to continue this work by repeating the experiments with powerful cancer treatments linked to the LXY1 molecule. They will begin with iodine-131, a form of radionuclide currently used to treat some cancers, as well as a nanoparticle, or "smart bomb," that would carry cancer-fighting drugs to diseased cells.

Additional UC Davis study authors were Wenwu Xiao, Nianhuan Yao, Li Peng and Ruiwu Liu. Their research was funded by a grant from the National Institutes of Health.

Gene Therapy Eliminates Brain Tumors Through Selective Recruitment Of Immune Cells

to harness the power of the immune system to eradicate brain tumors face two major hurdles: recruiting key immune cells called dendritic cells into areas of the brain where they are not naturally found and helping them recognize tumor cells as targets for attack.

Researchers at Cedars-Sinai Medical Center, however, have identified a sequence of molecular events that accomplish both objectives. Their findings, based on laboratory and animal studies, appear in the Jan. 13 issue of PLoS Medicine, an open-access online journal of the Public Library of Science.

The Cedars-Sinai team discovered that a protein – HMGB1 – released from dying tumor cells activates dendritic cells and stimulates a strong and effective anti-tumor immune response. HMGB1 does so by binding to an inflammatory receptor called toll-like receptor 2, or TLR2, found on the surface of dendritic cells.

"Toll receptors play a major role in the immune system's recognition of bacterial and viral components, but now we have shown that they also trigger an immune response against tumors," said Maria G. Castro, Ph.D., co-director of Cedars-Sinai's Board of Governors Gene Therapeutics Research Institute and one of the article's senior authors. "Activation of Toll receptors was essential for two key stages in initiating immune responses against the tumor – the migration of peripheral dendritic cells into the brain tumor and the subsequent activation of dendritic cells and stimulation of a specific anti-tumor cytotoxic T-cell mediated response."

Building on more than 10 years of research in this area, the researchers used a combined gene therapeutic approach, using one protein (Flt3L) to draw dendritic cells from bone marrow into the brain tumors, and a second protein (Herpes Symplex type I Thymidine Kinase, or TK), combined with the antiviral gancyclovir to kill tumor cells and elicit long-term survival. In this paper, they uncovered a novel mechanism by which tumor cell death in response to the treatment leads to the release of an endogenous tumor protein, HMGB1, which is essential to trigger the anti-tumor immunological cascade. The study showed for the first time that HMGB1 released from dying brain cancer cells activates TLR2 signaling on tumor infiltrating dendritic cells, resulting in the activation and expansion of tumor-antigen specific T cells. This caused the regression of the brain tumors and increased survival time by six months in experimental brain tumor models.

Glioblastoma multiforme is the most aggressive type of brain tumor, with only five percent of patients surviving five years following diagnosis. While new drugs have had some impact on survival rates, the traditional approaches to cancer treatment – surgery, radiation and chemotherapy – have failed to provide major improvements in long-term survival.

Immunotherapy – eradicating brain cancer cells by harnessing the patient's immune system – has been an attractive treatment approach, in theory. An effective anti-tumor immune response initially depends on dendritic cells that constantly "sample" the environment and can recognize unusual proteins, such as those belonging to cancers or infectious pathogens. However, since there are few dendritic cells in the brain, the immune responses in this organ are dampened when compared to those elicited in other parts of the body.

According to Pedro Lowenstein, M.D., Ph.D., director of the Board of Governors Gene Therapeutics Research Institute and co-senior author, "The discovery of a central role for HMGB1 and TLR2 in overcoming immune ignorance to brain tumor antigens provides a new therapeutic approach in the fight against brain tumors. Our conclusions relating to anti-glioma immune responses have also been extended to enhancing immune responses against a number of other metastatic brain cancers, such as melanoma."

He stated that plans are underway to test this novel therapeutic approach in a human clinical trial for recurrent brain tumors in 2009.

The work was supported by grants from the National Institutes of Health/National Institute of Neurological Disorders and Stroke, The Bram and Elaine Goldsmith and the Medallions Group Endowed Chairs in Gene Therapeutics, the Linda Tallen and David Paul Kane Foundation Annual Fellowship, the Joseph Drown Foundation and the Board of Governors at Cedars-Sinai Medical Center.

Nearly A Century Later, New Findings Support Warburg Theory Of Cancer

German scientist Otto H. Warburg's theory on the origin of cancer earned him the Nobel Prize in 1931, but the biochemical basis for his theory remained elusive.

His theory that cancer starts from irreversible injury to cellular respiration eventually fell out of favor amid research pointing to genomic mutations as the cause of uncontrolled cell growth.

Seventy-eight years after Warburg received science's highest honor, researchers from Boston College and Washington University School of Medicine report new evidence in support of the original Warburg Theory of Cancer.

A descendant of German aristocrats, World War I cavalry officer and pioneering biochemist, Warburg first proposed in 1924 that the prime cause of cancer was injury to a cell caused by impairment to a cell's power plant – or energy metabolism – found in its mitochondria.

In contrast to healthy cells, which generate energy by the oxidative breakdown of a simple acid within the mitochondria, tumors and cancer cells generate energy through the non-oxidative breakdown of glucose, a process called glycolysis. Indeed, glycolysis is the biochemical hallmark of most, if not all, types of cancers. Because of this difference between healthy cells and cancer cells, Warburg argued, cancer should be interpreted as a type of mitochondrial disease.

In the years that followed, Warburg's theory inspired controversy and debate as researchers instead found that genetic mutations within cells caused malignant transformation and uncontrolled cell growth. Many researchers argued Warburg's findings really identified the effects, and not the causes, of cancer since no mitochondrial defects could be found that were consistently associated with malignant transformation in cancers.

Boston College biologists and colleagues at Washington University School of Medicine found new evidence to support Warburg's theory by examining mitochondrial lipids in a diverse group of mouse brain tumors, specifically a complex lipid known as cardiolipin (CL). They reported their findings in the December edition of the Journal of Lipid Research.

Abnormalities in cardiolipin can impair mitochondrial function and energy production. Boston College doctoral student Michael Kiebish and Professors Thomas N. Seyfried and Jeffrey Chuang compared the cardiolipin content in normal mouse brain mitochondria with CL content in several types of brain tumors taken from mice. Bioinformatic models were used to compare the lipid characteristics of the normal and the tumor mitochondria samples. Major abnormalities in cardiolipin content or composition were present in all types of tumors and closely associated with significant reductions in energy-generating activities.

The findings were consistent with the pivotal role of cardiolipin in maintaining the structural integrity of a cell's inner mitochondrial membrane, responsible for energy production. The results suggest that cardiolipin abnormalities "can underlie the irreversible respiratory injury in tumors and link mitochondrial lipid defects to the Warburg theory of cancer," according to the co-authors.

These findings can provide insight into new cancer therapies that could exploit the bioenergetic defects of tumor cells without harming normal body cells.

Seyfried, Chuang and Kiebish were joined by co-authors Xianlin Han and Hua Cheng from the Washington University School of Medicine, Department of Internal Medicine, in St. Louis.

Inherited Factors Play Important Role In Breast Cancer Progression, According To New Study In Mice

mice and five independent collections of human breast tumors has enabled National Cancer Institute (NCI) scientists to confirm that genes for factors contributing to susceptibility for breast cancer metastasis can be inherited.

The new findings support earlier results from the same laboratory and appear in the Jan. 1, 2009, issue of Cancer Research.

The study results also show that gene activities in tumor cells and immune cells that infiltrate, or invade, tumors can contribute to the development of expression profiles, called gene signatures, that are predictive of cancer progression. The analysis of normal mouse tissue as well as tumors transplanted into mice suggests that predictive, or prognostic, gene signatures that point to a tumor’s potential for spreading throughout the body can be the result of both inherited and non-inherited factors, with inherited factors being more consistently predictive. The research team that reported these findings is from the Center for Cancer Research at NCI, which is part of the National Institutes of Health.

The researchers were able to perform their analyses by using advances in microarray technology, which allows scientists to scan vast amounts of genetic information and identify gene signatures that can be used to predict cancer outcomes. Many scientists had assumed that metastatic ability is primarily determined by somatic, or non-inherited, gene mutations in tumor tissue. "Our earlier studies clearly established that inherited factors also play an important role in metastatic progression and can help distinguish which tumors have a propensity to metastasize," said author Kent W. Hunter, Ph.D., head of NCI’s Metastasis Susceptibility Section in the Laboratory of Cancer Biology and Genetics. "Hopefully in the future we will be able to determine which women are more likely to have a tumor that would metastasize, and we could then tailor therapy specifically for them, avoiding the use of harsh treatments for those with a low probability of metastasis."

To determine whether mouse tumor gene expression profiles could be used to predict outcomes in human breast cancer, the investigators identified a gene expression signature that allowed them to distinguish between the tumors of mice that have a high or a low inherited susceptibility to tumor metastasis (a 20-fold difference). They then converted the mouse gene signature to the corresponding human gene signature and analyzed five pre-existing sets of human breast tumors. This signature successfully predicted outcomes (either relapse or disease-free survival) in four of the five sets of human breast tumors.

Because other studies have suggested that gene expression patterns in the nearby tissue, or stroma, are altered in tumors that are prone to metastasis, the investigators conducted transplant experiments by putting highly metastatic tumor cells into the mammary fat pads of mice that have either a high or a low susceptibility to tumor metastasis. These transplants resulted in tumors that had identical tumor cells but different stroma and immune cells that infiltrated the tumor. No significant differences were seen in tumor weight or metastasis to the lung in the two types of mice after 28 days, suggesting that metastatic differences between individual mice in this experiment were possibly due to genes in the outer layer of tissue that surrounds the tumor (the epithelium) rather than in the stroma.

However, differences in gene signatures were still seen in mice with either high or low potential to develop metastases, and the corresponding human gene signatures were predictive of relapse or survival in patients. The researchers concluded that both the tumor epithelium and the stroma probably contributed to the development of the prognostic gene profiles.

"Our study provides additional evidence of the role of inherited genes in human breast cancer progression. Therefore our next step is to improve our current understanding of the role of the epithelium and stroma in tumor progression and develop more effective therapeutic strategies based on our new knowledge," said Hunter.

Gene May Lead To Early Onset Of Brain Tumor

particular gene variant may be more likely to develop brain tumors, and at an earlier age, than people without the gene, according to a study published in the January 27, 2009, print issue of Neurology®, the medical journal of the American Academy of Neurology.

The study involved 254 people with brain tumors and 238 people with no cancers. All those with tumors had glioblastoma multiforme, the most common type of brain cancer. People with this type of tumor survive an average of 12 to 15 months.

Through blood samples, researchers looked at the tumor suppressor TP53 gene. This gene acts as a tumor suppressor and is involved in preventing cancer.

People younger than 45 with brain tumors were more likely to have the Pro/Pro variant of the gene than older people with brain tumors or the healthy participants. A total of 20.6 percent of the young people with brain tumors had the gene variant, compared to 6.4 percent of the older people with brain tumors and 5.9 percent of the healthy participants.

"Eventually we may be able to use this knowledge to help identify people who have a higher risk of developing brain tumors at an early age. However the risk of this population remains low, even multiplied by three or four as shown here, because these brain tumors (glioblastomas) are infrequent in young people," said study author Marc Sanson, MD, PhD, of the French National Institute of Health and Medical Research (INSERM) in Paris, France.

The study was supported by the Public Assistance Hospitals of Paris.

Individualized Approach To Breast Cancer Treatment

cancers are the same, and not all will have fatal consequences. But because clinicians find it difficult to accurately determine which tumors will metastasize, many patients do not receive the therapy fits their disease.

Tel Aviv University has now refined breast cancer identification so that each course of treatment is as individual as the woman being treated.

The new approach -- based on a combination of MRI and ultrasound -- is able to measure the metabolism rates of cancer cells. The approach helps determine at an earlier stage than ever before which cells are metastasizing, and how they should be treated.

The method, expected to start clinical trials in 2010, is currently being researched in Israel hospitals.

New Field of Medicine

“We have developed a non-intrusive way of studying the metabolism of breast cancer in real time,” says Dr. Ilan Tsarfaty, a lead researcher from TAU’s Sackler Faculty of Medicine. “It’s an invaluable tool. By the time results are in from a traditional biopsy, the cancer can already be radically different. But using our technique, we can map the tumor and its borders and determine with high levels of certainty — right away — which patients should be treated aggressively.”

The research falls in a new field called "translational and personalized medicine", and Dr. Tsarfaty says it has the potential to save thousands of lives. Papers describing his methodologies were published recently in the journals Cancer Research and Neoplasia.

“Current breast cancer treatments are not tailored to individual patients,” Dr. Tsarfaty says. “Our approach to profiling individual tumors will not only help save lives today, it will provide the basic research for developing cancer drugs of the future,” he says.

Application to Other Cancers

The new research can be applied to all solid tumors, including those resulting from lung and brain cancer, and could be used to respond to a wide spectrum of neurodegenerative diseases, such as Alzheimer’s, Dr. Tsarfaty reports.

Dr. Tsarfaty’s MRI-and-ultrasound-imaging application monitors the metabolic changes that occur during cancer metastasis. Increased blood flow (which can be sensed by ultrasound) and an increase of oxygen consumption (measured with an MRI) can indicate cancer metastasis with unprecedented levels of sensitivity.

Normally scientists look for structural changes in the body, such as the presence of a tumor. But with their new methods, Dr. Tsasfaty and his team which includes his wife, a radiologist are actually able to “see” cancer metastasis within a small group of cells long before the cancer spreads to other organs in the body.

Earlier Detection, Earlier Treatment

“Today, clinicians only diagnose cancer when they see a tumor several millimeters in size. But our diagnosis can be derived from observing only a few cells, and looks specifically at the activation levels of a protein called Met. Activated Met is an oncogen,” he says. “If the tumor cells show activation of Met, we can design personalized medicine to treat a specific kind of breast cancer.”

New Laser For Neurosurgery Allows Greater Precision And Efficiency For Removal Of Complex Tumors

Northwestern Memorial Hospital are among the first in the country to use a new micro-laser, which uses light energy in place of a cutting tool to remove complicated brain and spine tumors. The technique offers greater precision and efficiency during surgery, reducing the incision size, surgery time and patient recovery period following surgery.

Surgeons first used the laser in October when Stephen Abbott, a 70-year-old retired United States Army officer, presented with a brain tumor the size of a plum attached to one of the major veins draining blood from the brain. The tumor was discovered during a routine physical earlier in the year when a test indicated Mr. Abbott was experiencing some hearing loss.

Bernard Bendok, MD, a vascular and skull base neurosurgeon and Andrew Fishman, MD, a neurootologist and skull base surgeon, collaborated on the case and determined that Mr. Abbott was a prime candidate for surgery. The two then merged their specialties to operate on the complex tumor, using the laser, to help them remove the tumor quickly and safely. The removal of the tumor took less than one hour and after just five days Mr. Abbott was home, healthy and back to his daily routine.

The laser, called the BeamPath NEURO™, allows surgeons to direct CO₂ laser energy into deep holes and around blood vessels and other specific nerve structures and the brainstem. It is designed for operating near critical structures in the brain and spine and is used in place of a scalpel to cut tissue and remove tumors.

“When lasers were first used in neurosurgery some 30 years ago, surgeons were very excited, but it faded quickly because the devices were too cumbersome,” commented Dr. Bendok. “This new tool provides far greater control and precision in tight surgical corridors”

“The laser enables us to be much more efficient during surgery, we are able to remove tumors much more quickly which shortens overall surgery time,” commented Dr. Fishman. “That translates into a quicker recovery for patients.”

MR Spectroscopy May Help Avoid Invasive Procedures And Treatments For Recurrent Brain Lesions

model which uses MR spectroscopy to help physicians differentiate between recurrent tumors and changes in the brain tissue due to radiation treatments, may help patients avoid invasive procedures and treatments, according to a study performed at the University of Michigan Health System in Ann Arbor, MI.

The study included 33 patients who had undergone radiation treatment for brain tumors and had MRI examinations that showed new lesions (either a recurrent tumor or radiation changes). Patients then underwent MR spectroscopy and ratios of three metabolites, choline (Cho), creatine (Cr) and n-acetylaspartate (NAA) were calculated. An ROC curve and prediction model was then created, which determined the post-test probability of a patient having a recurrent tumor. For the study, the final number of patients with recurrent tumors was 20 and those with post-radiation change were 13.

“MR spectroscopy looks inside each area of the brain and determines concentrations of metabolites that are there,” said Ethan Smith, MD, lead author of the study. “Choline, creatine and NAA are the three metabolites that are most commonly looked at. They are found inside the cells of the brain and the ratios between each change depending on if the cells are malignant or benign. With further work, this technique could save some patients from unnecessary brain biopsies,” said Dr. Smith.

This study appears in the February issue of the American Journal of Roentgenology.

Newly Discovered Gene Could Be A Prime Target In The Most Lethal Brain Cancer

University Medical Center and Johns Hopkins University have discovered mutations in two genes that could become therapeutic targets in malignant glioma, a dangerous class of brain tumors.

"The fact that the defective genes code for metabolic enzymes found only in malignant glioma, and not in normal tissue, could make the gene products therapeutic targets," says Hai Yan, M.D., Ph.D., lead author, an assistant professor in the Duke Department of Pathology. The findings are published in the Feb. 19 issue of the New England Journal of Medicine.

These genetic flaws might also help distinguish between primary and secondary glioblastoma multiforme (GBM), two subtypes of especially deadly malignant gliomas, with survival of only months after their diagnosis. Patients that have mutation of the genes, isocitrate dehydrogenase 1, gene 1 and 2 (IDH1 and IDH2), also had a longer survival time.

Because the researchers found this genetic mutation in several different stages of glioma development, "the results suggested that the IDH mutations are the earliest genetic changes that start glioma progression," said Darell Bigner, M.D., Ph.D., a co-author and director of the Preston Robert Tisch Brain Tumor Center at Duke University. Yet, patients with GBM or anaplastic astrocytoma who had the IDH mutations also were found to live longer than patients with those two cancers who lacked the mutations.

Malignant glioma appears to be two diseases, one that involves IDH mutations and one that doesn't, Yan explained. "As a cancer culprit gene, IDH mutations do contribute to cancer," he said. "Meanwhile, patients with the IDH mutation live longer with their cancer. The IDH mutation could serve as a biomarker that would help single out individuals who are likely to have better outcomes and receive different treatment."

He said that IDH mutations appear to define a specific subtype of GBMs, which is important so that physicians can plan specific treatment strategies to target this specific subtype of GBMs. "All GBMs are basically considered the same and are treated in the same way," Yan said. "Our studies clearly demonstrate that we need to start thinking about them as different. It is entirely possible that treatments that work for the IDH-mutation subtype would not work for the rest of GBMs, or vice versa." Knowing the tumor subtype has significant implications for how we plan future clinical trials for patients with GBMs, he added.

"I can say this is potentially one of the most important discoveries in genetic studies on malignant gliomas, in the low-grade to high-grade forms of the tumor," Yan said. "The results are so clear cut. I have been doing intensive genetic studies in brain cancers for six years, and I have never seen gene mutations as striking as in this study."

The researchers found IDH1 mutations in more than 70 percent of astrocytomas and olidgodendrogliomas (WHO grade II and III), as well as in secondary GBMs (WHO grade IV). Those without the IDH1 mutation had similar mutations in the closely related IDH2 gene. The mutations decreased IDH enzymatic activity. This signaled that IDH mutations are likely important in initiating malignant gliomas, but it is not known yet how they contribute to glioma development.

The findings are important in many ways. IDH can be used to distinguish primary GBMs, which do not arise from an existing tumor, from secondary GBMs, which arise from low-grade glioma tumors. The IDH1 mutation is missing in pilocytic astrocytomas, which means these particular brain tumors arise through a different mechanism.

Dr. William Parsons of Johns Hopkins Kimmel Cancer Center contributed equally with Dr. Yan to the article. Other authors included Genglin Jin, Ph.D., Roger McLendon, M.D., and B. Ahmed Rasheed, Ph.D., from the Duke Department of Pathology; Ivan Kos, Ph.D., and Ines Batinic-Haberle, Ph.D., of the Duke Department of Radiation Oncology; Henry Friedman, M.D., of Duke Neuro-Oncology; and Allan Friedman, M.D., and David Reardon, M.D., of the Duke Department of Surgery, members of the Pediatric Brain Tumor Foundation Institute and the Preston Robert Tisch Brain Tumor Center; and James Herndon, Ph.D., of the Duke Cancer Statistical Center. The remaining authors came from the Ludwig Center for Cancer Genetics and Therapeutics and the Howard Hughes Medical Institute at Johns Hopkins Kimmel Cancer Center, the Johns Hopkins Department of Neurosurgery, the Department of Pediatrics at Baylor College of Medicine, and the Center for Drug Evaluation and Research of the U.S. Food and Drug Administration.

Funding came from the Pediatric Brain Tumor Foundation Institute, a Damon Runyon Foundation Scholar Award, a grant from the Southeastern Brain Tumor Foundation, Alex's Lemonade Stand Foundation, a grant from the V Foundation for Cancer Research, the Virginia and D.K. Ludwig Fund for Cancer Research, the Pew Charitable Trusts, the American Brain Tumor Association, the Brain Tumor Research Fund at Johns Hopkins, grants from Beckman Coulter, grants from the Accelerate Brain Cancer Cure Foundation, and several National Institutes of Health grants. Drs. Yan, Bigner and Parsons plus four Johns Hopkins scientists reported being eligible for royalties received by Johns Hopkins University on sales of products related to research described in this study, under licensing agreements between the university and Beckman Coulter.

Brain Cells' Hidden Differences Linked To Potential Cancer Risk

lumped into the same category have hidden differences that may contribute to the formation of tumors, according to a new study from researchers at Washington University School of Medicine in St. Louis.

Scientists showed that brain cells known as astrocytes make use of different genes depending on what region of the mouse brain they came from. These differences are too subtle to overtly mark them as distinct cell types, but substantial enough to make it easier for the cells to multiply more in response to genetic changes that increase cancer risk.

"We've shown that identical-looking astrocytes from different brain regions are genetically distinct, and these molecular differences may alter the risk for cancer development," says senior author David H. Gutmann, M.D., Ph.D., the Donald O. Schnuck Family Professor of Neurology.

In recent years, Gutmann has shown that the transition from a normal to a cancerous cell is heavily influenced by factors outside the cell, such as growth factors and other signals from neighboring cells. He calls the new finding the "yin" to the earlier research's "yang."

According to Gutmann, these dual lines of research show that there are two factors that explain why tumors form in some brain regions and not in others. First, the cell must live in a brain region that provides the right environmental signals to facilitate tumor formation. Second, as revealed by the new research, the cell itself also must be responsive to those environmental signals.

"In this regard, tumor formation and growth requires both a permissive environment and a receptive cell type," Gutmann says.

All of the body's cells have the same genes, but different cell types turn genes on and off or use certain genes more or less often. These patterns of activating and inactivating genes both allow cells to grow and develop into specialized structures and to take on specialized roles at the level of individual cells. Astrocytes, for example, have properties that allow them to support other brain cells.

To gain insights into the significance of potential genetic differences between astrocytes from different brain regions, Gutmann and his colleagues used a mouse model of a common inherited cancer syndrome, neurofibromatosis type 1 (NF1). In children with NF1, brain tumors typically arise in the optic nerve and brainstem and only rarely appear in the cortex. The condition is caused by a mutation in a gene known as the neurofibromatosis 1 gene.

When Gutmann and post-doctoral researcher Tu-Hsueh Yeh, M.D., Ph.D., examined astrocytes from different brain regions under the microscope and in other standard tests, the astrocytes looked similar. But when the researchers analyzed gene activity levels — which genes the cells used to make proteins and how often they were used — sharp differences became apparent. For example, astrocytes from the cortex have low levels of neurofibromatosis-1 gene expression compared to astrocytes from the optic nerve or brainstem.

In addition, when they disabled the neurofibromatosis 1 gene in cell culture and in the mouse brain, they found what Gutmann called "dramatically increased" growth in astrocytes from the brainstem and optic nerve. In contrast, the same change had no effect on growth of astrocytes from the cortex.

"These exciting results suggest that not all astrocytes are the same, and that genetic differences between astrocyte populations may partly dictate where brain tumors form in children with NF1," says Gutmann. "Future studies aimed at understanding the complex interplay between environmental signals and receptive cell types may lead to an improved understanding of brain tumor formation and help us customize our treatments in ways that improve their effectiveness."

Funding from the National Institutes of Health and the National Cancer Institute supported this research.

Case Report Of A Brain And Spinal Tumor Following Human Fetal Stem Cell Therapy

published in PLoS Medicine, describes a rare side effect of human fetal stem cell therapy. Ninette Amariglio and Gideon Rechavi from the Sheba Medical Center, Tel Aviv, Israel, and colleagues report the case of a boy with a rare genetic disease, Ataxia Telangiectasia, who underwent human fetal stem cell therapy at an unrelated clinic in Moscow and who, four years after the therapy began, was shown to have abnormal growths in his brain and spinal cord.

There have been reports in rodents of the development of tumors following the injection of pluripotential embryonic stem cells into recipient animals, although the risk of such tumors can be reduced if the cells are differentiated before being injected. However, this report is the first documented example of such a complication in a human following neural fetal stem cell therapy.

The spinal cord growth was surgically removed and this was shown to resemble a glioneuronal tumor – a type of benign neural tumor. The authors describe the process by which they analyzed the tumor and documented that it could not have arisen from the patient's own tissues. For example, the tumor contained both XX (female) and XY (male) cells and had two normal copies of the ATM gene (the gene causing Ataxia Telangiectasia, which was mutated in the patient).

The authors discuss the extremely rare nature of this side effect and speculate that the patient's underlying condition may itself have allowed the tumor to become established, since individuals with Ataxia Telangiectasia often have an impaired immune system. Although this report indicates the need for caution in stem cell therapy, the authors conclude that their findings "do not imply that the research in stem cell therapeutics should be abandoned. They do, however, suggest that extensive research into the biology of stem cells and in-depth preclinical studies, especially of safety, should be pursued in order to maximize the potential benefits of regenerative medicine while minimizing the risks."

Gene Mutations That Cause Childhood Brain Cancer Identified

funded by the Canadian Cancer Society have discovered eight similar genes that, when mutated, appear to be responsible for medulloblastoma – the most common of childhood brain cancers. The findings are published March 8 in the online edition of the journal Nature Genetics.

"This discovery is very promising and may help researchers develop better, more targeted treatments so that more of these children will survive and fewer will suffer debilitating side effects," says Dr. Christine Williams, Director of Research Programs, Canadian Cancer Society Research Institute.

Dr. Michael Taylor, who has a $600,000 research grant from the Canadian Cancer Society, led the study: "When these eight genes are functioning normally, we believe their role is to make a protein which tells the developing brain when it's time to stop growing. But when the genes are mutated, the brain may continue to grow out of control, leading to cancer.

"Drugs are already being developed that target these types of proteins," he says. "Our hope is that some of these drugs may be adapted and used effectively to treat medulloblastomas." Dr. Taylor is a pediatric brain surgeon at Toronto's Hospital for Sick Children:

In the study, the largest of its kind, researchers looked at more than 200 tumour samples. The samples came from children in countries all over the world including Canada, the US, England, Poland and Saudi Arabia. Paul Northcott, a PhD student in Dr Taylor's lab, analyzed and interpreted all the data over a period of 3 ½ years. "We've learned more from this study about the genetic basis of this disease than from any other previous study," Northcott says. The gene mutations they found had not been suspected as culprits in cancer formation.

About 250 Canadian children are diagnosed with various types of brain cancer every year. About 70 per cent of these survive. Brain tumours are the leading cause of childhood cancer deaths. The most common childhood brain cancer is medulloblastoma – a tumour that occurs at the back of the brain in the cerebellum. It is primarily a disease of very young children and is particularly deadly among babies under 18 months of age. In Canada, about 40 children are diagnosed with medulloblastoma every year and half of these will survive.

Many survivors experience serious physical and neurological problems from the disease itself and from the effects of very aggressive treatments on the developing brain. Treatments include surgery, radiation and chemotherapy.

Brain Tumor Treatment May Increase Number Of Cancer Stem-like Cells

suggests that the standard treatment for a common brain tumor increases the aggressiveness of surviving cancer cells, possibly leaving patients more vulnerable to tumor recurrence. The research, published in the March 6th issue of the journal Cell Stem Cell, provides valuable insight into the molecular mechanisms that enable cancer stem-like cells to escape cytotoxic treatment and repopulate the tumor.

Glioblastoma multiforme is the most prevalent and aggressive form of primary brain tumor and is notoriously resistant to standard therapies. Dr. Eric Holland, from Memorial Sloan-Kettering Cancer Center in New York, examined the role of ABCG2, a protein linked with drug resistance, in glioma cancer stem-like cells. "ABC proteins are transporters that participate in tumor resistance by actively transporting drugs across the cell membrane, serving to protect cells from chemotherapeutic agents," offers Dr. Holland.

Dr. Holland and colleagues employed a method that allowed visualization of ABC-mediated efflux of fluorescent dye to identify and isolate "side population" (SP) cells from mouse and human glioblastomas. "Because the SP phenotype in glioma cancer stem-like cells is mainly mediated by ABCG2, as shown by the almost complete abolition of this phenotype when ABCG2 activity is blocked, we subsequently studied the oncogenic potential of ABCG2," explains Dr. Holland.

The researchers confirmed that SP cells are highly tumorigenic, have the ability to self-renew, and are resistant to chemotherapy. These results verified that ABCG2 activity, although not by itself oncogenic, is a marker for glioma stem-like cells. Further, the researchers identified a detailed molecular mechanism that modulates the activity of ABCG2 and enhances the ability of cancer stem-like cells to expel drugs.

Importantly, Dr. Holland's group also found that the chemotherapeutic drug temozolomide, the standard treatment for gliomas, increased the number of glioma cells with stem-like characteristics. The researchers speculated that because temozolomide is not an ABCG2 substrate, the increase in the SP fraction likely resulted from enrichment of cells with stem-like properties. "In the process of increasing the number of cells in tumors with stem-like properties, temozolomide may render surviving cells even more resistant to subsequent treatment with drugs that are substrates for ABCG2," explains Dr. Holland.

The researchers include Anne-Marie Bleau, Dolores Hambardzumyan, Tatsuya Ozawa, Elena I. Fomchenko, Jason T. Huse, Cameron W. Brennan, and Eric C. Holland, of the Memorial Sloan-Kettering Cancer Center, New York, NY.

Cell Pathway On Overdrive Prevents Cancer Response To Dietary Restriction

Whitehead Institute researchers have pinpointed a cellular pathway that determines whether cancerous tumors are susceptible to dietary restriction during their development. When this pathway, known as PI3K is permanently turned "on" via mutation, tumors grow and proliferate independent of the amount of food consumed.

However, when the PI3K pathway operates normally, tumors respond to dietary restriction—defined as food consumption limited to 60% of normal--and become smaller in size.

Scientists have known about the correlation between dietary restriction and tumor growth since the early 20th Century. These findings bring clarity to the long-unanswered question of why certain tumors are unaffected by reduced caloric intake.Whitehead Institute researchers have pinpointed a cellular pathway that determines whether cancerous tumors respond to dietary restriction during their development.

Studying human cancer cell lines in mice, researchers have found that when this pathway, known as PI3K, is activated permanently via mutation, tumors grow and proliferate independent of food consumption. However, when the PI3K pathway operates normally, dietary restriction (defined as a 60% reduction in normal intake), results in smaller tumors. The findings are published online in the March 11 issue of Nature.

"Our findings indicate that each tumor cell bears a signature that determines whether or not that cell will be affected by dietary restriction," says Nada Kalaany, first author of the paper and a postdoctoral researcher in the lab of Whitehead Member David Sabatini. "We think that mutations in the PI3K pathway are a major determinant of the sensitivity of tumors to dietary restriction."

The connection between food consumption and tumor growth is not new. In the early 20th Century, scientists first noted the correlation between a restricted diet and decreased tumor size and incidence. However, some cancers' growth rate was unaffected by a decrease in food consumption. The reason for this difference remained unclear.

To determine how various tumor types are affected by dietary resistance, Kalaany injected cells from human prostate, breast, brain, and colon cancers into mice in an experimental protocol used frequently to study human cancers. The mice then ate as much as they liked (control group) or received 60% of the caloric intake of their counterparts (the dietary restriction (DR) group). Both groups ingested the same amounts of vitamins and minerals. After a few weeks, Kalaany saw that the cancers could be divided into DR-sensitive tumors, with significantly lower tumor volumes in the DR mice than in control mice, or DR-resistant tumors, whose sizes were apparently unaffected by normal or restricted diets.

Kalaany then grew the same cancer cells in Petri dishes to see how the DR-sensitive and DR-resistant cancers respond to food-related hormones in the body. The cancers were grown solutions containing increasing amounts of insulin, insulin-like growth factor 1 (IGF1) or in a solution without these hormones. The results supported the previous experiment: those cancer cells that were DR-sensitive in the mice were also stunted by a lack of insulin and IGF1; those cancer cells that were DR-resistant in the mice were unaffected by changes in insulin and IGF1 levels.

Because the difference between the two groups was sensitivity or insensitivity to insulin and IGF1, Kalaany thought the insensitive tumors may have something amiss in a cellular process called the PI3K pathway, which is activated by insulin/IGF1. A search for mutations in two genes found in the PI3K pathway that are often associated with cancer (PI3KCA and PTEN), revealed that DR-resistant cells had mutations in one or the other of the genes, while DR-sensitive cells showed no such mutations.

Using a DR-resistant tumor cell line in which the PTEN gene could be switched on or off, Kalaany tested whether a change in the PTEN gene alone could affect a tumor's sensitivity to DR. When the PTEN gene was turned off, the cancer cells were not affected by dietary restriction, and tumor size increased similarly in control and DR mice. But when PTEN was turned on, thereby restoring normal function to the PI3K pathway, the cells became sensitized to dietary restriction and tumor size was smaller in the DR group.

This research was confirmed in two mouse models of cancer, one with prostate cancer caused by PTEN deletion and one with lung cancer and a functioning PTEN gene. Again, the mice without the PTEN gene did not respond to dietary restriction, but the mice with a functioning PTEN gene were sensitive to dietary restriction.

Sabatini says that Kalaany's results could lead to cancer treatments tailored to the characteristics of an individual patient's tumor cells.

"Her findings suggest that if we have therapies that mimic dietary restriction, we could better predict which tumors would respond to those dietary restriction-mimicking drugs and which ones would not," says Sabatini.

Sabatini is also intrigued by the inverse relationship between too much food and an increase in tumors. "We already know that the United States has an epidemic of obesity and that obesity is probably the biggest contributor to cancer in the U.S., even more so than smoking. Does this research have anything to do with that correlation between obesity and cancer, that if we make animals really obese, that this pathway is also involved in determining their sensitivity to cancer? Answering that question is the next step."

New Investigational Treatment For Bladder Cancer Identified

A team of researchers, led by Columbia University Medical Center faculty, has identified a new investigational therapy for the treatment of bladder cancer. The discovery was made using a new research model, using mice, which replicates many aspects of human bladder cancer. The model also enabled the researchers to demonstrate that two major tumor suppressor genes, p53 and PTEN, are inactivated in invasive bladder cancer.

The findings and this new model are described in a paper in the March 15, 2009 issue of Genes & Development.

The new model disrupts a signaling pathway, known as mTOR, which blocks tumor growth. Inhibiting mTOR with a drug called rapamycin was found to significantly slow the progression of bladder tumors in mice.

The research was led by Drs. Cory Abate-Shen and Carlos Cordon-Cardo, both professors in the Departments of Urology and Pathology & Cell Biology and associate directors in the Herbert Irving Comprehensive Cancer Center of Columbia University Medical Center and NewYork-Presbyterian Hospital.

"We believe that this new mouse model of human bladder cancer will be invaluable to the field of bladder cancer research. Already it has provided a relevant preclinical model for therapeutic investigations and a strong rationale for targeting the mTOR signaling pathway in patients with invasive bladder cancer," said Dr. Abate-Shen.

"Importantly, the new insights that this model has provided about the role of the inactivation of both p53 and PTEN in invasive bladder cancer may enable oncologists to more quickly identify patients with invasive disease, who may need aggressive treatment to slow the progression of their bladder cancer," said Dr. Cordon-Cardo, who is associate director for research infrastructure at the Herbert Irving Comprehensive Cancer Center and vice-chair of pathology at Columbia University Medical Center.

Bladder cancer is a serious health problem worldwide; it is the fifth most common malignancy and a major cause of cancer morbidity and mortality. Until now, there have been few mouse models that properly replicate the invasive capabilities of this disease, leaving researchers with few tools to help them develop new therapeutic approaches for combating it.

"This new mouse model is enormously important for the study of bladder cancer," said Daniel P. Petrylak, M.D., associate professor of medicine at Columbia University College of Physicians & Surgeons and Director of the Genitourinary Oncology Program at New York-Presbyterian Hospital/Columbia.

"Based on the initial findings about the efficacy of inhibiting the mTOR signaling pathway with rapamycin in the mouse model, I am excited to be collaborating with Dr. Abate-Shen to further investigate the implications of this research," said James McKiernan, M.D., the John and Irene Given Associate Professor and director of urologic oncology at the Herbert Irving Comprehensive Cancer Center, who was not involved in the study.

Role of p53 and PTEN in Bladder and Other Cancers

P53 and PTEN have been found to be mutated in a significant number of advanced cancers, in bladder cancer representing approximately 41 percent of the invasive tumors and previously published research has demonstrated that their combined inactivation has profound consequences for tumor growth in many contexts, including lymphoma, prostate cancer and brain tumors. In 1997, Ramon Parsons, M.D., Ph.D., at Columbia University College of Physicians and Surgeons, led one of two teams that independently identified PTEN and discovered that knocking out PTEN sends a strong pro-growth signal on tumor cells.

New Theoretical Model Of Tumor Growth And Metastasis Based On Differences In Tissue Pressure

The progression of cancer is a multi-step process. Over 80% of malignant tumors are carcinomas that originate in epithelial tissues from where they invade the connective tissue. At some point, subpopulations of cells may detach from the primary tumor and spread via the bloodstream and the lymphatic system. Some of them give rise to metastases in distant organs.

The metastatic cascade is a very inefficient process, as only one in about a thousand cells that leave the primary tumor goes on to form a macroscopic secondary tumor. The main contribution to metastatic inefficiency arises from the failure of cancerous cells to grow inside invaded organs. Metastatic tumors also show preferential growth in different organs. Hence, the efficiency of the metastatic process depends on specific interactions between the invading cancer cells and the local organ tissues.

In an Article published on the HFSP Journal website, Risler, Prost and Joanny from Institut Curie in Paris suggest that this is due to a difference of pressure between tumor cells and the host tissue. Combining the laws of mechanics and the biological state of homeostasis, the authors propose that every biological tissue regulates to a preferred pressure called homeostatic pressure, and that an increased homeostatic pressure is a generic trait of neoplastic tissues. This property can drive tumour growth at the expense of the host tissue. Metastases account for the majority of patients' deaths due to cancer, and thus understanding the metastatic process is of critical importance.

New Tumor Markers Determine Therapy Intensity

changes in the DNA of medulloblastoma, the most frequent malignant brain tumor in childhood, indicate precisely how aggressively the tumor will continue to spread and what the chances of disease relapse are. Researchers at the Center for Pediatric and Adolescent Medicine at the Heidelberg University Hospital and the German Cancer Research Center have discovered this correlation. With this new set of tumor markers, the intensity of treatment can be adjusted individually and the potentially damaging effects reduced.

The results have now been published online in the Journal of Clinical Oncology.

Medulloblastoma is the most frequent childhood brain tumor

The most common malignant brain tumor in childhood is the medulloblastoma – every year, more than 100 children in Germany develop this tumor of the cerebellum and some 30-40 children die from it. The first symptoms generally appear at primary school age, but the tumor, which can already arise during embryonal development, can also occur in babies and toddlers. Aggressive radiation and chemotherapy regimens after surgery can permanently damage the brain of the growing child, for example, leading to coordination disorders and limited growth.

"Using the characteristic changes in the genetic makeup of medulloblastoma, we can predict more accurately than with conventional methods how a patient will respond to therapy and how great the risk is that the tumor will return after surgery and subsequent radiation and chemotherapy," explained Dr. Stefan Pfister, who works with his team in the department of pediatric oncology at the Center for Pediatric and Adolescent Medicine (Medical Director: Professor Dr. Dr. Andreas Kulozik) and in the department of molecular genetics at the German Cancer Research Center (Director: Professor Dr. Peter Lichter). Thus far, oncologists could estimate this risk only on the basis of histology findings, age at diagnosis, residual tumor after surgery, and existence of metastases at diagnosis.

Patients with a poor prognosis can be treated more intensively

Stefan Pfister and his research group "Molecular Genetics of Pediatric Brain Tumors" first described the new tumor markers in the medulloblastoma in 2007. For the current study, he examined tumor samples from 340 patients and compared the documented course of disease with genetic aberrations in the tumor DNA. Aberrations were seen at the chromosome level, the units in which the entire genetic information is distributed and contained. Each chromosome contains large amounts of genetic information; the entire genetic material of humans is distributed in 23 such portions, each of which is usually present in two copies (2 x 23 chromosomes). Stefan Pfister discovered that if entire segments of chromosomes number 6 and 17 are present in three copies (instead of the usual 2 copies) in the genetic material of the brain tumors, the patient's prognosis is poor. If however, one copy of chromosome 6 is missing in the tumor, the patients in the collective observed always survived. The combination of these and other characteristics led to a classification of the patients in a total of five groups requiring varying levels of intensity in treatment.

"With these markers, we can reliably identify patients with a poor prognosis and treat them more intensely from the start," said Dr. Stefan Pfister. "At the same time, we can reduce the treatment intensity for patients who will presumably respond especially well to radiation and chemotherapy. We can thus reduce consequential damage and the risk of secondary malignancies."

Another advantage of the new markers – the test is very robust and can be carried out within 48 hours in any neuropathology laboratory on tissue samples conventionally preserved in paraffin.

BMBF promotes the search for other tumor markers

The prospective validation of these markers in an independent patient cohort and the search for the simplest and most reliable methods of analysis is now the goal of a project promoted by the Federal Ministry for Education and Research (BMBF) entitled "Molecular Diagnostics," in which the university hospitals of Bonn, Mainz, Düsseldorf, Würzburg, and Heidelberg as well as the German Cancer Research Center in Heidelberg are participating under the coordination of Dr. Stefan Pfister.

Biological Clue In Brain Tumor Development

University of Nottingham have uncovered a vital new biological clue that could lead to more effective treatments for a children’s brain tumour that currently kills more than 60 per cent of young sufferers.Clinician –scientists at the University’s Children’s Brain Tumour Research Centre, working on behalf of the Children’s Cancer and Leukaemia Group (CCLG), have studied the role of the WNT biological pathway in central nervous system primitive neuroectodermal tumours (CNS PNET), a type of brain tumour that predominantly occurs in children and presently has a very poor prognosis.

In a paper published in the British Journal of Cancer, they have shown that in over one-third of cases, the pathway is ‘activated’, suggesting that it plays a role in tumour development. The research also highlighted a link between WNT pathway activation and patient survival — patients who had a CNS PNET tumour that was activated survived for longer than those without pathway activation.

The reason for the link between WNT pathway activation and better patient prognosis is as yet unclear. It could be that these tumours represent a less aggressive subset or that pathway activation itself actually harms the tumour. However, the pathway could represent an important new target for the treatment of more effective drugs, with fewer side effects.

Senior author Professor Richard Grundy, from the Children’s Brain Tumour Research Centre, said: “The principal aim of our research is to reduce the morbidity and mortality of children with central nervous system tumours through improved understanding of tumour biology. Following on from this, we need to translate this knowledge into effective new treatments for brain tumours through the development and assessment of accurately targeted treatments that will cause fewer side effects than conventional chemotherapy or radiotherapy and be more effective. The ultimate aim is to develop ‘drugs’ that target just the abnormal genes in cancer cells, rather than the current norm which involves the indiscriminate destruction of dividing cells which might be healthy or malignant. Overall, this is an important finding in a poorly understood, poor prognosis disease, which we hope, in time, will lead to the development of new treatments for CNS PNETs.

“We hope our findings will lead to a more detailed understanding of CNS PNETS, which is crucial if we are to ensure each child receives the most appropriate treatment for their disease and that we reduce the number of children in which their cancer recurs.”

In total, around 450 children and young adults under 18 years are diagnosed with a brain tumour each year in the UK. Overall, 60 per cent of children with the cancer in the UK can be successfully treated, but survival for CNS PNETs is less than 40 per cent.

Funding was provided by the Connie and Albert Taylor Trust, The Samantha Dickson Brain Tumour Trust, the Brain Tumour Research Fund Birmingham Children’s Hospital Special Trustees.

Native Kidney Cancer in a Kidney Transplant Recipient

Question
What is your recommendation for a patient with native kidney cancer stage pT2 discovered 3 years after kidney transplantation? The graft is doing well, but I am afraid to continue with full immunosuppression.

Sergio Ximenes, MD
Expert Response from Velma Scantlebury, MD
Professor of Surgery; Chief, Division of Transplantation, Department of Transplant, University of South Alabama Medical Center, Mobile, Alabama

I will assume that this patient had a T2 lesion without nodes or metastases since it was not mentioned. Lesions that are low-grade, < 2 cm, and asymptomatic are less likely to become problematic. With nephrectomy being the treatment of choice, alterations in immunosuppression might be recommended because of the lower survival rates of chronically immunosuppressed patients compared with nonimmunocompromised patients. If the patient is on triple immunosuppression and has had little or no problems with rejection, then perhaps lowering or discontinuing the third agent should be considered. Follow-up of this patient with routine surveillance is important, as are evaluation of the remaining native kidney with ultrasound every 6 months and computed tomography scans yearly.

Targeting Cancer Cells -- More Pathways, More Inhibitors, More Trials

Sara M. Mariani, MD, PhD
Introduction

Although some may be a bit puzzled by the ever-increasing number of small molecular inhibitors being tested for their anticancer activity, the limited efficacy shown by available compounds, the restricted range of activity, or the significant rate of resistance development is prompting researchers in academic and industrial laboratories to look for more and better inhibitors of cancer growth and survival.

Multiple signaling pathways or intracellular compartments are under the "microscope" for their potential therapeutic relevance in cancer treatment -- the insulin growth factor pathway (IGF), the mTOR pathway, the ubiquitin-proteasome system, histone deacetylases (HDACs), and Aurora kinases -- as illustrated by lead investigators at the 9th Annual Drug Discovery Technology World Congress, recently held in Boston, Massachusetts.

Targeted inhibitors are now available for most of these signaling pathways and systems. Multiple in vitro and in vivo testing is unveiling their characteristics and will ultimately determine which of them will indeed represent a viable strategy that meaningfully improves on current anticancer treatments.

As learned from the introduction of the first small molecular inhibitors in the past few years, activity, safety, tolerability (if long-term treatments are envisioned), and cost-benefit ratios will ultimately be the parameters determining their success for cancer patients. Identification of specific biomarkers and clinical end points to measure relative antitumor activity, as well as an accurate selection of responsive patients, will add to their applicability and clinical use.

A Survey of Kidney Disease and Risk-Factor Information on the World Wide Web

Abstract

Background: Chronic kidney disease (CKD) is epidemic, and informing those at risk is a national health priority. However, the discrepancy between the readability of health information and the literacy skills of those it targets is a recognized barrier to communicating health information that may promote good health outcomes. Because the World Wide Web has become one of the most important sources of health information, we sought to assess the readability of commonly available CKD information.
Methods: Twelve highly cited English-language, kidney disease Web sites were identified with 4 popular search engines. Each Web site was reviewed for the availability of 6 domains of information germane to CKD and risk-factor information. We estimated readability scores with the Flesch-Kincaid and Flesch Reading Ease Index methods. The deviation of readability scores for CKD information from readability appropriate to average literacy skills and the limited literacy skills of vulnerable populations (low socioeconomic status, health disparities, and elderly) were calculated.
Results: Eleven Web sites met the inclusion criteria. Six of 11 sites provided information on all 6 domains of CKD and risk-factor information. Mean readability scores for all 6 domains of CKD information exceeded national average literacy skills and far exceeded the fifth-grade-level readability desired for informing vulnerable populations. Information about CKD and diabetes consistently had higher readability scores.
Conclusion: Information on the World Wide Web about CKD and its risk factors may not be readable for comprehension by the general public, especially by underserved minority populations with limited literacy skills. Barriers to health communication may be important contributors to the rising CKD epidemic and disparities in CKD health status experienced by minority populations.

Caring for Patients With Chronic Kidney Disease: A Joint Opinion of the Ambulatory Care and the Nephrology Practice and Research Networks of the Ameri

Abstract and Introduction
Abstract

An increasing number of patients are developing chronic kidney disease (CKD). Appropriate care for patients with CKD must occur in the earliest stages, preferably before CKD progresses to more severe stages. Therefore, recognition and treatment of CKD and its associated complications must occur in primary care settings. Patients with CKD often have comorbid conditions such as diabetes mellitus, hypertension, and dyslipidemia, creating specific considerations when treating these diseases. Also, these patients have CKD-related conditions, including anemia and renal osteodystrophy, that are not traditionally evaluated and monitored by the primary care practitioner. Collectively, many opportunities exist for pharmacists who practice in the primary care setting to improve the care of patients with CKD.
Introduction

Chronic kidney disease (CKD) is a health problem reaching epidemic proportions and encompasses a substantial segment of the adult ambulatory population. Although specific prevalence rates are difficult to calculate, an estimated 20 million people have CKD.[1] More specific data are available for the subset of patients with end-stage renal disease (ESRD), or renal failure, where the incidence reached almost 100,000 patients in 2000.[2] This number has doubled during the past 10 years and is expected to increase with the aging population. By 2010, the incidence of ESRD is projected to increase to more than 172,000 cases annually.[2] Similarly, the prevalence of ESRD was 372,000 cases in 2000 but is estimated to exceed 661,000 by 2010.[2] The cost of treating patients with ESRD consumes almost 6% of the total Medicare budget, accounting for approximately $19 billion annually. Although these are staggering numbers, they account for only the 2% of patients in the final stage of CKD. Millions of patients with less severe CKD represent a much broader portion of the adult ambulatory population. Therefore, the recognition and treatment of early CKD should be emphasized as a component of primary care.

The presence of CKD doubles the risk of mortality in affected individuals.[2] Meanwhile, progression to ESRD incurs a very poor prognosis, with patients having a 4 times greater rate of hospitalizations and a life expectancy that is one quarter to one fifth less than that of the general population. By far, the most common cause of death (48%) among patients with ESRD is cardiovascular disease.[3] Thus, an opportunity for improving care of patients with CKD exists through treatment of cardiovascular risk factors during earlier stages of the disease in primary care. Current treatment recommendations stress the importance of therapies that improve the morbidity and mortality of these patients, as well as therapies that prevent or delay the progression of kidney disease.[4] Most of these therapeutic interventions target the adult, ambulatory patient population in primary care. Pharmacists in a wide variety of primary care practice settings are well suited to implement and monitor therapeutic interventions to improve the care of patients with CKD.

The Emerging Role of Targeted Therapy in the Treatment of Advanced Renal Cell Carcinoma

Introduction

Renal cell carcinoma (RCC) accounts for approximately 36,000 cases yearly in the United States. Approximately 60% of patients with RCC are cured with initial surgical resection. However, treatments have been largely ineffective in the remaining 40% of patients who either have metastatic disease at diagnosis, or who develop recurrence following initial surgical resection.

Standard cytotoxic agents are largely ineffective, producing response rates of less than 10%.[1,2] High dose interleukin (IL)-2 has been highly active in a small subset of patients, producing major clinical benefit with long-term remissions in 5% to 10% of patients.[3,4] However, the large majority of patients have no benefit with this therapy, and the high level of toxicity precludes treatment in many older patients. Therefore, more effective treatments are urgently needed for

Radiofrequency Ablation of Renal Cell Carcinoma: Part 2, Lessons Learned with Ablation of 100 Tumors

Abstract and Introduction
Abstract

Objective: The objective of our study was to review radiofrequency ablation of 100 renal tumors and lessons learned with respect to electrode approach, effects on collecting system, bowel proximity, and patterns of residual disease.
Materials And Methods: Over 6 years, 100 renal tumors in 85 patients underwent radiofrequency ablation. Images were reviewed to determine the following: effect of initial electrode approach at and parallel to the tumor-kidney interface; effect of collecting system proximity to the tumor and to the zone of ablation; bowel proximity to the tumor and strategies to protect bowel; patterns of residual disease; and approaches at subsequent sessions.
Results: The initial placement of the electrode at and parallel to the tumor-kidney interface did not result in significantly fewer overlapping ablations (p = 0.91) or a lower rate of residual disease (p = 0.86). Direct contiguity of tumor or zone of ablation to the collecting system did not increase the complication rate. However, obscuration of calyces by a central tumor was a significant predictor of collecting system hemorrhage necessitating treatment (p < 0.001) seen in three of nine tumors obscuring calyces. Clinically significant urine leaks were rare (1/100) and related to downstream obstruction. There were no bowel complications despite the fact that 27 of the tumors were within 1 cm of bowel. Protective strategies progressed from reliance on electrode positioning to hydrodissection. Residual patterns were predominantly nodules or crescents, and straight electrodes were commonly used to approach residual disease.
Conclusion: Initial electrode position at and parallel to the tumor-kidney interface does not result in less difficult or more successful ablations. Contiguity of tumor or zone of ablation to the collecting system does not increase the risk of complications, but obscuration of calyces does. Bowel complications are rare, and protection with hydrodissection is becoming more common. Residual tumor presents as nodules or crescents of persistent enhancement.
Introduction

Radiofrequency ablation is being used increasingly to treat patients with small renal masses who are not ideal candidates for surgery.[1-7] In part 1 of our two-article series Radiofrequency Ablation of Renal Cell Carcinoma,[8] we reported the clinical experience and follow-up of 100 renal cell carcinomas that underwent radiofrequency ablation. Several additional issues with respect to radiofrequency ablation of renal masses can be addressed on the basis of current experience. Here in part 2, we review lessons learned such as the effect of the angle of approach of the electrode to an exophytic mass and the effects of radiofrequency ablation on the collecting system based on tumor proximity and bowel proximity to tumor, considerations for bowel displacement, patterns of residual disease, and approach to repeat ablation.

Radiofrequency Ablation of Renal Cell Carcinoma: Part 1, Indications, Results, and Role in Patient Management Over a 6-Year Period and Ablation of 100

Abstract and Introduction
Abstract

Objective: The objectives of our article are to review our experience with radiofrequency ablation of renal cell carcinoma and to assess size and location as predictors of the ability to achieve complete necrosis by imaging criteria.
Materials and Methods: Over a 6-year period, 100 renal tumors in 85 patients underwent radiofrequency ablation at a single institution. The absence of enhancement on CT or MRI after radiofrequency ablation was interpreted as complete coagulation necrosis. Results were analyzed by tumor size and location using multivariate analysis. A p value of 0.05 or less was considered significant.
Results: All 52 small (3 cm) and all 68 exophytic tumors underwent complete necrosis regardless of size, although many large tumors (> 3 cm) required a second ablation session. Using multivariate analysis, we found that both small size (p < 0.0001) and noncentral location (p = 0.0049) proved to be independent predictors of complete necrosis after a single ablation session. Location was a significant predictor (p = 0.015) of complete necrosis after any number of sessions, whereas size showed a strong trend (p = 0.059) toward predicting success after any number of sessions. Complications were either self-limited or readily treated and included hemorrhage (major, n = 2; minor, n = 3), inflammatory track mass (n = 1), transient lumbar plexus pain (n = 2), ureteral injury (n = 2), and skin burns (n = 1).
Conclusion: Radiofrequency ablation is a promising minimally invasive therapy for renal cell carcinoma in patients who are not good operative candidates. Small size and noncentral location are favorable tumor characteristics, although large tumors can sometimes be successfully treated with multiple ablation sessions.
Introduction

The incidence of renal cell carcinoma is increasing, with most renal cell carcinomas now being detected as incidental imaging findings.[1-3] The desire to preserve renal function in patients with comorbid conditions or with multiple renal cell carcinomas has been the impetus for the development of minimally invasive therapies such as partial nephrectomy and laparoscopic nephrectomy.[4,5] The newest of these minimally invasive therapies are the ablative therapies such as radiofrequency ablation and cryoablation.[6,7] As determined by imaging criteria, the short-term effectiveness of percutaneous imaging-guided radiofrequency ablation in treating small renal cell carcinoma has been shown and validated in several early studies over the past 5 years.[6,8-15]

As new therapies are introduced, 5-year results are compared with those for conventional open nephrectomy. Although the literature currently contains several series of small renal cell carcinomas treated with percutaneous radiofrequency ablation, all these series report mean low follow-up periods of less than 2 years.[8-15] Thus, 5-year results of substantial cohorts of patients are awaited. Nevertheless, several issues with respect to performance of radiofrequency ablation of renal masses can be addressed on the basis of current experience. We undertook these studies to review our experience with radiofrequency ablation of 100 renal masses. In this article, part 1, we review indications, technique, results based on size and location, clinical and imaging follow-up, and complications. In part 2, we review technical considerations such as patterns of residual disease and approach to ablation of residual disease, effects on the collecting system, considerations for bowel displacement, and angle of approach of the electrode relative to the mass.

The Natural History of Small Renal Masses

Summary and Introduction
Summary

The incidence of renal cell carcinoma is increasing, in part due to the growing use of cross-sectional imaging. Most renal tumors are now incidentally detected as small masses in asymptomatic patients. A minority of small renal masses, presumed to be renal cell carcinoma, grow significantly over time if managed conservatively, but the growth rate of the majority is slow or undetectable. In the absence of other prognostic factors, measurement of tumor growth rate can be helpful for initial conservative management of selected patients with small renal tumors. To date, there have been no reports of progression to metastatic disease occurring during active surveillance, but longer follow-up is needed to confirm this observation. The standard of care for small localized renal neoplasms is partial or radical nephrectomy. At the present time, active surveillance of small renal masses, with delayed therapy for patients whose disease progresses, is an experimental approach that can be considered for the elderly or patients with significant comorbidity. Renal core biopsy and fine-needle aspiration can provide essential information for treatment decision-making and should therefore be considered in the diagnostic work-up of all small renal masses. In future, the identification of prognostic indicators, with the use of new techniques including functional imaging and molecular or genomic characterization of tissue from needle biopsies, are expected to help clinicians differentiate between indolent and potentially aggressive small renal tumors.
Introduction

Malignant tumors of the kidney are responsible for about 2% of cancer incidence and mortality in the US, with an estimated 36,160 new cases and 12,660 deaths in 2005.[1] There has been an increase of 126% in the incidence of renal cell carcinoma (RCC) in the US since 1950.[2] This rising trend has been observed worldwide and is partially due to the growing use of new and improved noninvasive abdominal imaging modalities, such as ultrasonography, CT and MRI.[2,3,4,5]

The increasing incidence of RCC has occurred across all clinical stages, but the greatest increase has been observed in the incidence of localized tumors, with an average annual increase of 3.7% from 1973 to 1998 in the US.[3,4] In more recent years, 48 to 66% of RCCs have been detected incidentally as SMALL RENAL MASSES in asymptomatic patients, whereas historically most cases were diagnosed following investigations for flank pain or hematuria.[6,7,8] Tumor size at diagnosis has also decreased substantially over time. The Memorial Sloan-Kettering Cancer Center reported a drop in the mean size of resected renal tumors from a maximum diameter of 7.8 cm to 5.3 cm between 1989 and 1998.[9]

The largest increase in incidentally detected renal tumors has occurred among patients aged 70-89 years, presumably because these individuals are more likely to undergo radiologic examination for other medical issues.[3]

There are numerous reports suggesting that incidentally detected lesions are, on average, smaller and present at an earlier stage than those detected in symptomatic patients.[4,5,7,9,10,11,12,13] Compared to symptomatic renal masses, small asymptomatic masses are more frequently benign and those confirmed as RCCs are, on average, lower grade.[5,7,14,15,16] Frank et al. reviewed the pathology of 2,935 renal tumors at the Mayo Clinic. They observed that as tumor size decreases there is a significant increase in the likelihood of a benign histology, a papillary compared to a clear-cell histology and a low-grade compared to a high-grade malignancy. In their experience, 30% of tumors below 4 cm in their maximum dimension were benign and over 87% of those diagnosed as clear-cell RCCs were low-grade tumors.[15]

Finally, several authors have reported that small incidentally detected tumors are associated with better survival outcomes.[5,11,12,14,17] The 5-year disease-free survival rate for incidental renal tumors of <4 cm treated with radical or partial nephrectomy is 95-100%.[9,10] Bell was the first author to report an association between renal tumor size and prognosis, when he noted an increased rate of metastases in patients found to have RCCs >3 cm in maximum dimension at autopsy compared to those with RCCs of 3 cm.[18] Tumor size is a key component of the tumor-node-metastasis (TNM) staging system and remains the most important prognostic factor for RCC.

Natural history Of small renal masses The NATURAL HISTORY of small renal masses has not been extensively studied because most tumors are surgically removed soon after diagnosis; however, Table 1 lists the outcomes of some studies which have examined ACTIVE SURVEILLANCE of small renal masses.

In the landmark report of surveillance of kidney tumors, Bosniak et al. retrospectively reviewed the imaging of 40 incidentally detected <3.5 cm renal masses that had been followed up for a mean of 3.25 years (range 1.75-8.5 years). Of 26 tumors that were eventually removed after an average of 3.8 years (range 1.8-8.5 years), 22 (84.6%) were histologically confirmed as RCC. Variable tumor growth rates were observed, but the overall mean linear growth rate for all tumors was 0.36 cm/year (0-1.1 cm/year). Nineteen tumors grew at a rate of <0.35 cm/year and no patient developed metastatic disease.[19] More recently, Oda et al. observed 16 patients with incidentally diagnosed and histologically proven localized RCC. The tumor growth rate varied from 0.10 to 1.35 cm/year and was significantly lower than that of metastatic RCC lesions.[20]

In the first prospective study of watchful waiting for renal tumors, we reported a series of 13 patients incidentally diagnosed with a small <4 cm renal mass and followed expectantly because they were elderly or unfit for surgery. We hypothesized that the tumors that are destined to grow fast, and possibly metastasize, do so early, while most small tumors grow at a slow rate or not at all.[21] We have subsequently reported the Results of active surveillance of an expanded series of 32 renal masses in 29 patients. Of the 32 masses, 25 were solid masses and 7 were complex cysts (four were BOSNIAK CATEGORY III RENAL LESIONs and three were BOSNIAK CATEGORY IV RENAL LESIONs). The patients were prospectively followed up with serial abdominal imaging for a mean of 27.9 months (range 5.3-143 months), with at least three follow-up measurements carried out on each mass. Tumor volume, in addition to single and bidimensional diameters, was calculated from each follow-up image or report. After an average of 38 months of follow-up, nine masses in eight patients were surgically removed either because of the surgeon's concern or the patient's anxiety that the tumor was enlarging. All tumors were clear-cell RCCs, with the exception of one oncocytoma. The overall average growth rate was low and showed no correlation with either initial size or mass type. Seven masses (22%) reached 4 cm in diameter after 12 to 85 months of follow-up and eight (25%) doubled their volume within 12 months. Overall, 11 (34%) fulfilled one of these two criteria of rapid growth. No patient progressed to metastatic disease; two patients died of unrelated causes.[22]

Kassouf et al., who serially imaged 24 patients with small renal masses, have since reported a similar experience. Most of the tumors demonstrated no significant growth during the surveillance period and no metastases were documented, with a mean follow-up of 31.6 months.[23]

In another study, 29 small, incidentally detected, contrast-enhancing renal masses were followed with serial CT imaging. In 15 patients no tumor growth occurred during follow-up. Six patients were eventually treated for significant tumor growth or at the request of the patient. Pathology was obtained in five cases (four RCCs and one oncocytoma). No patients died of RCC or developed metastatic disease.[24]

Kato et al. reported on the natural history of 18 incidentally detected and histologically proven RCCs that were surgically removed after a median observation period of 22.5 months. The average annual growth rate was 0.42 cm, and FUHRMAN GRADE III tumors, which comprised 17% of the series, grew faster than FUHRMAN GRADE I-II tumors. The authors found a significant correlation between tumor growth rate and apoptotic activity measured with the TUNEL technique, but no correlation between tumor growth rate and proliferative activity measured by Ki-67 immunostaining.[25] Interestingly, Lamb et al. also observed a slow growth rate in larger renal tumors. They followed a series of 36 renal masses with an average size of 7.2 cm at diagnosis, in patients who were considered unsuitable for surgery or were unwilling to have surgery. Two-thirds of the masses were biopsied and the diagnosis of RCC was confirmed in all cases except one. The authors observed a growth rate of 0.0-1.76 cm/year, with 55% of patients showing no increase in tumor size. Only one patient, who had a high-grade tumor at biopsy, eventually developed metastases 132 months after the initial diagnosis.[26]

The studies on active surveillance that have been published to date are mostly retrospective, have a relatively short follow-up period and include a limited number of patients. Their Results are consistent, however, and clearly suggest that a large proportion of incidentally detected small renal masses have a slow growth rate and an indolent clinical behavior, if managed conservatively. Rare cases of small renal tumors presenting with distant metastases at diagnosis have been described in the literature, but, to date, we are unaware of a case in which a small renal mass that was either presumed or proven to be RCC has metastasized during the surveillance period.[27]

Compared to the large increase in the detected incidence of RCC in recent years, the mortality rate of RCC has increased only modestly. This could be due to a lead-time bias, or might further support the theory that many small renal tumors have a long natural history and are not destined to progress, while those likely to do so are probably resected too late despite their localized radiographic appearance.[1,2,3,4,28] Furthermore, reports from autopsy series performed before the widespread use of imaging show that 67-74% of RCCs remained undetected until death and that only 8.9-20% of undiagnosed RCCs were eventually responsible for the patient's death.[29,30]

The watchful-waiting series described above comprised mostly elderly patients. This population may not be entirely representative of all patients presenting with a small renal mass. The biology of small renal tumors may differ in younger patients. A report from the Mayo Clinic observed that patients aged 18-40 years were more likely to have chromophobe than clear-cell RCCs when compared to patients that are 60-70 years old. The tumors in the younger group were also more likely to be cystic and to present at a lower stage, all features that have been shown to be associated with a favorable prognosis.[31]

Imaging and biopsy of small renal masses Measurement error at imaging is a key concern in the management of patients with small renal tumors. Accurate edge detection of an irregular mass at imaging can be difficult, particularly in the presence of features such as hemorrhage, pyelonephritis, cysts or dilated calices adjacent to the tumor, multiple cysts within the kidney and localization near or invasion of the collecting system.[32] We have performed a study of interobserver and intraobserver variability in CT measurement of small renal masses, comparing volumes estimated on imaging with postoperative volumes. Although it is well known that differences between these measurements can occur as a result of decreased kidney and tumor blood volume in the surgical specimen caused by initial ligation of the arterial blood supply, we have demonstrated that measurement of the dimensions of a renal tumor based on CT scans and MRI offers an accurate means of assessing tumor growth.[33]

Renal masses with cystic components present a special problem because their growth rate can be easily overestimated or underestimated if the volume of cystic fluid grows at a different rate to the tumor cell volume. Some authors have observed that the prognosis for patients with cystic RCC is better than that for patients with solid tumors, but, as the tumors were all managed by surgery, these reports do not give us information about the natural history of this type of tumor.[34,35] In our experience, complex cystic renal masses have a comparable growth rate to that of solid tumors.[22]

Historically, needle-core biopsies of renal masses have been recommended to rule out the presence of metastatic disease to the kidney, renal abscess or lymphoma and to confirm the diagnosis of a renal-cell primary tumor in patients with disseminated metastases or unresectable tumors. Beyond these indications, renal needle biopsies have not been widely performed in North America because of concerns about complications, tumor seeding and sampling errors. However, the techniques and Results of needle biopsy of renal masses under imaging guidance have significantly improved over time and the associated risks have significantly decreased. Fine-needle aspiration and core biopsy of renal masses now appear to be safe and can be performed in an outpatient setting with a low morbidity rate.[36,37,38] A high degree of accuracy can now be achieved, both in obtaining tissue and interpreting it with routine pathologic techniques. The sensitivity and specificity of renal tumor biopsy reported in the literature are 70-92% and 100% respectively, with accuracy close to 90%.[39]

Neuzillet et al. reported the Results of helical CT-guided percutaneous fine-needle biopsy on 88 consecutive patients with solid, small (<4 cm in maximum dimension) renal masses. Adequate material for histologic examination was obtained from 96.6% of the patients. In 5.6% of cases pathology revealed only fibrosis and was considered inconclusive; 15.9% of the masses were found to be benign. Following diagnosis of RCC at biopsy, 62 patients underwent radical or partial nephrectomy. The sensitivity of the biopsy was 92% for diagnosis of malignancy and tumor subtype. There was a weaker correlation between the Fuhrman grade, as determined by biopsy, and the final tumor grade (70%); however, no tumor was erroneously graded by more than one point. There were no false-positive Results and no significant postbiopsy complications or track seeding were reported.[38] One of the major concerns with needle-core biopsies of renal tumors is the risk of misdiagnosing or undergrading tumors as a result of histologic heterogeneity. We recently reviewed our personal experience and observed that intratumoral heterogeneity does not represent a significant issue in small renal tumors (A Evans, A Saravannan, A Volpe and MA Jewett, unpublished data).

On the basis of their Results, Neuzillet et al. advocate the routine use of needle biopsies to better characterize the histology of small renal masses before surgical or conservative treatment. We believe that all patients who are incidentally diagnosed with a small renal mass should undergo a biopsy before being enrolled in an active-surveillance protocol.

Angiotensin II and EGF Receptor Cross-talk in Chronic Kidney Diseases: A New Therapeutic Approach

Abstract and Introduction

Abstract

Mechanisms of progression of chronic renal diseases, a major healthcare burden, are poorly understood. Angiotensin II (AngII), the major renin-angiotensin system effector, is known to be involved in renal deterioration, but the molecular pathways are still unknown. Here, we show that mice overexpressing a dominant negative isoform of epidermal growth factor receptor (EGFR) were protected from renal lesions during chronic AngII infusion. Transforming growth factor-α (TGF-α) and its sheddase, TACE (also known as ADAM17), were induced by AngII treatment, TACE was redistributed to apical membranes and EGFR was phosphorylated. AngII-induced lesions were substantially reduced in mice lacking TGF-α or in mice given a specific TACE inhibitor. Pharmacologic inhibition of AngII prevented TGF-α and TACE accumulation as well as renal lesions after nephron reduction. These findings indicate a crucial role for AngII-dependent EGFR transactivation in renal deterioration and identify in TACE inhibitors a new therapeutic strategy for preventing progression of chronic renal diseases.

Introduction

Regardless of etiology, most human kidney diseases are characterized by an initial injury, followed by progression of renal lesions to complete parenchymal destruction and end-stage renal failure.^[1] Clinical and experimental studies have shown that angiotensin II (AngII), the major renin-angiotensin system effector, has an important role in the biological process leading to renal deterioration. Indeed, pharmacological inhibition of the renin-angiotension system attenuates development of renal lesions in several experimental models of renal injury^[2] and retards progressive loss of renal function in individuals with chronic kidney disease (CKD).^[3] Conversely, individuals with genetic variants associated with higher renin-angiotensin system activity are at increased risk for progression of chronic renal failure.^[4] It has been suggested that AngII causes renal injury through renal hemodynamic effects and stimulation of kidney growth and matrix deposition,^[5] but the molecular pathways underlying these phenomena remain largely unidentified.

AngII acts on at least two structurally and pharmacologically distinct G-protein-coupled receptors (GPCRs), AT₁ and AT₂ (ref. 6). Renal cells predominantly express AT₁ receptors, which mediate the majority of known AngII actions.^[7] AT₁ receptors activate Gq-phospholipase C to generate inositol triphosphate and diacylglycerol, thereby increasing intracellular calcium and stimulating protein kinase C.^[8] Additionally, activation of AT₁ receptors promotes tyrosine phosphorylation and stimulates mitogen-activated protein kinases and proliferation.^[9,10] How AT₁ receptors, which lack intrinsic tyrosine kinase activity, induce these events is unclear, but recent evidence suggests that 'transactivation' of the epidermal growth factor receptor (EGFR) is involved,^[11] and may require several intermediary signaling molecules including Ca²⁺, protein kinase C and cytosolic tyrosine kinases.^[9] Recently, it has been shown that metalloprotease-dependent release of EGFR ligands from cells is also involved in GCPR-induced EGFR transactivation.^[12] Whether and by which molecular mechanisms AngII transactivates EGFR in renal cells during kidney diseases is unknown.

EGFR binds members of a family of growth factors, comprised of EGF, transforming growth factor-α (TGF-α), heparin-binding EGF-like growth factor, amphiregulin, epiregulin, betacellulin and epigen.^[13] All family members are synthesized as membrane-anchored precursors that can be processed by specific metalloproteases to release soluble bioactive factors from the cell surface.^[13] In the kidney, both EGFR and its ligands are abundantly expressed along the nephron, suggesting a paracrine-autocrine system.^[14,15] Addition of EGFR ligands to tubular cells promotes several biological responses in vitro, including cell proliferation,^[16] mesenchymal-epithelial transdifferentiation^[17] and collagen production.^[18] In vivo, activation of EGFR is thought to be involved in the evolution of renal diseases.^[19] Overexpression of the EGFR-related c-erb-B2 receptor induces tubular hyperplasia and the development of renal cysts in transgenic mice.^[20] Conversely, expression of a dominant negative isoform of EGFR in proximal tubules inhibits tubular cell proliferation and interstitial collagen accumulation, leading to reduced renal lesions after nephron reduction.^[21] Other genetic and pharmacological approaches have confirmed the role of EGFR in tubular cyst formation and cell proliferation in polycystic kidney diseases,^[22,23] and in renal fibrosis in an experimental model of hypertension.^[24] Collectively, these results suggest that EGFR could be a major determinant in the development of renal lesions, possibly through enhanced cell proliferation and matrix deposition.

We hypothesized that EGFR transactivation is crucial to the lesion-promoting effects of AngII in the kidney. Using transgenic mice and pharmacological inhibitors, we show that inhibition of the EGFR pathway prevents development of AngII-induced renal lesions. Furthermore, we provide evidence that TACE (tumor necrosis factor-α converting enzyme, also known as ADAM17) and TGF-α are crucial intermediates between AngII signal and EGFR transactivation during kidney diseases, and we identify a new therapeutic target.