Biochemical and Epigenetic Insights into L-2-Hydroxyglutarate, a Potential Therapeutic Target in Renal Cancer.

Abstract

Elevation of L-2-hydroxylgutarate (L-2-HG) in renal cell carcinoma (RCC) is due in part to reduced expression of L-2-HG dehydrogenase (L2HGDH). However, the contribution of L-2-HG to renal carcinogenesis and insight into the biochemistry and targets of this small molecule remains to be elucidated. Genetic and pharmacologic approaches to modulate L-2-HG levels were assessed for effects on <i>in vitro</i> and <i>in vivo</i> phenotypes. Metabolomics was used to dissect the biochemical mechanisms that promote L-2-HG accumulation in RCC cells. Transcriptomic analysis was utilized to identify relevant targets of L-2-HG. Finally, bioinformatic and metabolomic analyses were used to assess the L-2-HG/L2HGDH axis as a function of patient outcome and cancer progression. L2HGDH suppresses both <i>in vitro</i> cell migration and <i>in vivo</i> tumor growth and these effects are mediated by L2HGDH's catalytic activity. Biochemical studies indicate that glutamine is the predominant carbon source for L-2-HG via the activity of malate dehydrogenase 2 (MDH2). Inhibition of the glutamine-MDH2 axis suppresses <i>in vitro</i> phenotypes in an L-2-HG-dependent manner. Moreover, <i>in vivo</i> growth of RCC cells with basal elevation of L-2-HG is suppressed by glutaminase inhibition. Transcriptomic and functional analyses demonstrate that the histone demethylase KDM6A is a target of L-2-HG in RCC. Finally, increased L-2-HG levels, <i>L2HGDH</i> copy loss, and lower L2HGDH expression are associated with tumor progression and/or worsened prognosis in patients with RCC. Collectively, our studies provide biochemical and mechanistic insight into the biology of this small molecule and provide new opportunities for treating L-2-HG-driven kidney cancers.