Abstract B005: Metabolic liabilities in high L-2HG kidney cancer
Authors: Kundu Anirban , Brinkley Garrett J. , Nam Hyeyoung , Karki Suman , Absher Devin , Placzek William J. , Locasale Jason , Rakheja Dinesh , Darley-Usmarc Victor , Tennessen Jason , Sudarshan Sunil 
Published: August 2023

Abstract
Renal cell carcinoma (RCC) is among the top 10 cancers in the USA. Despite several approved therapies, patients with the advanced disease rarely have durable responses and therefore, face a poor prognosis (median survival 2-3 years). This underscores the need for new strategies. Alterations in metabolism are well-established in cancers including RCC. The oncometabolite, L-2-hydroxyglutarate (L-2HG) is elevated in the most common form of RCC (clear cell histology) and promotes tumor progression. However, L-2HG’s roles in RCC progression and its mediated therapeutic vulnerability are yet to be explored. RCC cell lines lack the L-2HG dehydrogenase enzyme (L2HGDH) which results in their high L-2HG level. RNA-seq of control (high L-2GH) and an L2HGDH reconstituted (low L-2HG) RCC cell line reveals that L-2HG suppresses the expression of serine biosynthesis genes, PHGDH and PSAT1. In agreement, high L-2HG renal tumors demonstrate lower levels of serine biosynthesis enzymes compared to their matched normal kidneys. Mechanistic studies reveal L-2HG-mediated remodeling of both the epigenome and epitranscriptome suppress serine biosynthesis genes. Consistently, 13C-metabolomics labeling studies demonstrate that raised L-2HG suppresses de novo serine biosynthesis. Moreover, LC-MS analysis of the metabolites isolated from the kidneys of L2hgdh KO and wild-type (WT) mice revealed lower serine levels in L2hgdh KO kidneys. In accordance with these data, found that high L-2HG RCC cells require exogenous serine for in vitro proliferation and in vivo tumor growth. Likewise, the pharmacologic blockade of serine uptake decreases the proliferation of high L-2HG RCC cells. Furthermore, this serine liability can be rescued upon lowering cellular L-2HG levels. Untargeted metabolomics analyses demonstrate that exogenous serine is required to maintain cellular pools of glutathione (GSH+GSSG) in high L-2HG RCC. This is particularly relevant as glutathione is among the most highly enriched metabolites in RCC compared to normal kidneys. Our metabolomics data also suggest that serine might be essential for the transsulfuration process of glutathione biosynthesis in RCC that lacks the xCT system required to uptake cysteine for transsulfuration. In vivo, we find that intratumoral levels of glutathione are reduced in mice fed a chow diet lacking serine compared to regular chow diet-fed mice. Pharmacologic inhibition of glutathione synthesis ablates the growth of high L-2HG RCC cells even in the presence of serine, suggesting the importance of redox homeostasis for RCC proliferation. The data indicate that the L-2HG elevation in RCC reconfigures tumor metabolism, resulting in serine liability. Collectively, our data unmask a metabolic vulnerability that can be harnessed for precision-based approaches to kidney cancer.
Citation Format: Anirban Kundu, Garrett J. Brinkley, Hyeyoung Nam, Suman Karki, Devin Absher, William J. Placzek, Jason Locasale, Dinesh Rakheja, Victor Darley-Usmarc, Jason Tennessen, Sunil Sudarshan. Metabolic liabilities in high L-2HG kidney cancer [abstract]. In: Proceedings of the AACR Special Conference: Advances in Kidney Cancer Research; 2023 Jun 24-27; Austin, Texas. Philadelphia (PA): AACR; Cancer Res 2023;83(16 Suppl):Abstract nr B005.