Kidney cancer

Over 65,000 Americans are diagnosed with kidney cancer each year and nearly 13,000 die of this disease. Kidney cancer is not a single disease, it is made up of a number of different types of cancer, each with a different histology, a different clinical course, responding differently to therapy and caused by a different gene. Study of the thirteen genes that are known to cause kidney cancer has led to the understanding that kidney cancer is a metabolic disease. Recent discoveries of chromatin remodeling/histone modifying genes, such as PBRM1 and SETD2, has opened up new areas of intense interest in the study of the fundamental genetic basis of kidney cancer. New approaches to immunotherapy with agents such as the CTLA4 inhibitor, ipilumumab, have opened up promising new directions for clinical trials. A number of new agents targeting of VEGF receptor signaling and the mTOR pathways as well as novel approaches targeting HIF2 will hopefully provide the foundation for the development of effective forms of therapy for this disease

VHL inactivation in renal cell carcinoma: implications for diagnosis, prognosis and treatment

Clear cell renal cell carcinoma (ccRCC) provides a tumor paradigm for the integration of genetics, molecular biology, therapeutic target validation, and the introduction of high impact treatment strategies. Most cases of sporadic as well as familial ccRCC acquire somatic inactivating mutations of the von Hippel-Lindau tumor suppressor gene, VHL. pVHL, VHL gene product and a protein member of the E3 ubiquitin ligase family, acts in normal cells to direct the degradation and clearance of the hypoxia inducible factor (HIFα) transcription factor family, such that in its absence, as in ccRCC, the HIF proteins stabilize, accumulate to supraphysiologic levels, and activate the transcription of genes such as vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF), which contributes substantially to the physiology of the tumor, and has been assessed indirectly as a prognostic factor. Molecularly targeted therapy blocking components of this pathway has been successfully introduced to the clinic with a substantive impact on clinical parameters of RCC. This review will examine the regulation of these molecular pathways in RCC and discuss the impact on the clinical management of patients with RCC

HIF1α and HIF2α Exert Distinct Nutrient Preferences in Renal Cells

Background: Hypoxia Inducible Factors (HIF1α and HIF2α) are commonly stabilized and play key roles related to cell growth and metabolic programming in clear cell renal cell carcinoma. The relationship of these factors to discretely alter cell metabolic activities has largely been described in cancer cells, or in hypoxic conditions, where other confounding factors undoubtedly compete. These transcription factors and their specific roles in promoting cancer metabolic phenotypes from the earliest stages are poorly understood in pre-malignant cells. Methods: We undertook an analysis of SV40-transformed primary kidney epithelial cells derived from newborn mice genetically engineered to express a stabilized HIF1α or HIF2α transgene. We examined the metabolic profile in relation to each gene. Results: Although the cells proliferated similarly, the metabolic profile of each genotype of cell was markedly different and correlated with altered gene expression of factors influencing components of metabolic signaling. HIF1α promoted high levels of glycolysis as well as increased oxidative phosphorylation in complete media, but oxidative phosphorylation was suppressed when supplied with single carbon source media. HIF2α, in contrast, supported oxidative phosphorylation in complete media or single glucose carbon source, but these cells were not responsive to glutamine nutrient sources. This finding correlates to HIF2α-specific induction of Glul, effectively reducing glutamine utilization by limiting the glutamate pool, and knockdown of Glul allows these cells to perform oxidative phosphorylation in glutamine media. Conclusion: HIF1α and HIF2α support highly divergent patterns of kidney epithelial cell metabolic phenotype. Expression of these factors ultimately alters the nutrient resource utilization and energy generation strategy in the setting of complete or limiting nutrients

Renal Cell Carcinoma: Where Will the State-of-the-Art Lead Us?

Less than 20 years ago, the von Hippel-Lindau (VHL) gene was discovered and associated with sporadic renal cell carcinoma (RCC). Since then, researchers and clinicians have labored to better understand the biology driving RCC tumor progression and provide means to predict patient survival and response to therapy. Studies surrounding VHL inactivation and downstream effects continue to provide insights into these areas. Besides studies of this primary pathway, cytogenetic studies, gene expression analyses, tissue microarrays, serum proteomics, genomic resequencing, and microRNA profiling have yielded greater understanding of RCC biology and clinical presentation, and have led to a rich understanding of the heterogeneity of this disease. We review the current state of research investigations into the molecular biology of RCC, and discuss the applications to currently used clinical prognostic nomograms

Hickey MM, Lam JC, Bezman NA, Rathmell WK, Simon MC.. von Hippel-Lindau mutation in mice recapitulates Chuvash polycythemia via hypoxia-inducible factor-2alpha signaling and splenic erythropoiesis. J Clin Invest 117: 3879-3889

The R200W mutation in the von Hippel-Lindau (VHL) tumor suppressor protein (pVHL) is unique in that it is not associated with tumor development, but rather with Chuvash polycythemia, a heritable disease characterized by elevated hematocrit and increased serum levels of erythropoietin and VEGF. Previous studies have implicated hypoxia-inducible factor-1alpha (HIF-1alpha) signaling in this disorder, although the effects of this mutation on pVHL function are not fully understood. In order to explore the mechanisms underlying the development of this polycythemia, we generated mice homozygous for the R200W mutation (Vhl(R/R)). Vhl(R/R) mice developed polycythemia highly similar to the human disease. The activity of HIF proteins, specifically the HIF-2alpha isoform, was upregulated in ES cells and tissues from Vhl(R/R) mice. Furthermore, we observed a striking phenotype in Vhl(R/R) spleens, with greater numbers of erythroid progenitors and megakaryocytes and increased erythroid differentiation of Vhl(R/R) splenic cells in vitro. These findings suggest that enhanced expression of key HIF-2alpha genes promotes splenic erythropoiesis, resulting in the development of polycythemia in Vhl(R/R) mice. This mouse model is a faithful recapitulation of this VHL-associated syndrome and represents a useful tool for studying polycythemias and investigating potential therapeutics