Regulation of the Kidney Cancer Epigenome by Oncometabolite L-2-Hydroxyglutarate

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PROJECT SUMMARY. Renal cell carcinoma (RCC) is among the 10 most common malignancies in both men and women. Unfortunately, progress in the treatment of patients with advanced disease has been incremental, and new treatment approaches are warranted. Altered metabolism, an established hallmark of malignancy, may provide novel therapeutic opportunities. Oncometabolites, small molecules with putative transforming properties, represent one of the clearest links between metabolism and cancer. A unifying theme amongst the oncometabolites identified to date is their ability to alter the epigenome via inhibition of enzymes involved in DNA and histone demethylation. In the context of RCC, there is increasing recognition of the role of epigenetics to the pathogenesis of this malignancy. However, the drivers of the RCC epigenome remain poorly characterized. The long-term goal of our laboratory is to understand the role of metabolism in renal carcinogenesis to develop novel therapies that will improve outcomes. The objective of this proposal is to identify the metabolic basis for the epigenetic landscape of RCC and to determine the effects on tumorigenesis. Studies by our laboratory and others have identified elevations of the putative oncometabolite (L)-2- hydroxyglutarate (L-2HG) in RCC as well as brain tumors. Elevations of L-2HG in RCC are due to reduced expression of L2HGDH (L-2HG dehydrogenase) which is located on chromosome 14q. Intriguingly, 14q loss is associated with a DNA hypermethylation phenotype, therapy resistance, and worsened outcomes in RCC patients. The central hypothesis of this proposal is that L-2HG is a powerful epigenetic modifier that drives the malignant phenotype of RCC. This hypothesis is based on strong preliminary data demonstrating that re- expression of L2HGDH in RCC cells (and thus lowering of cellular L-2HG levels) can reverse epigenetic modifications and suppresses both in vitro and in vivo tumor phenotypes. Additionally, high L-2HG tumors from patients demonstrate a RCC hypermethylator phenotype. In Aim 1, we will dissect the genetic and biochemical events that lead to L-2HG accumulation. In Aim 2, we will determine the contribution of L-2HG to the hypermethylator phenotype and assess the effects on gene expression utilizing methodologies including next generation sequencing with methylome array. In Aim 3, we will determine the mechanism by which L2HGDH suppresses tumor growth. In addition, we will assess the role of L2HGDH loss in tumor initiation and progression using novel genetic models. The proposed research is significant because it will identify the drivers of the RCC epigenome in the context of targetable pathways. The approach is innovative because it will establish a link between the epigenome and tumor metabolism in RCC. Ultimately, the knowledge gathered has the potential to improve the efficacy of treatment for patients with advanced RCC, an unmet need challenging the contemporary management of this disease.