The SLC1A1/EAAT3 dicarboxylic amino acid transporter is an epigenetically dysregulated nutrient carrier that sustains oncogenic metabolic programs

Abstract

Epigenetic dysregulation, including accumulation of Histone H3 lysine 27 acetylation (H3K27ac), is a hallmark of pVHL-deficient clear cell Renal Cell Carcinomas (ccRCCs). Using an in vivo positive selection ORF screen in poorly tumorigenic pVHL-proficient cells and mechanistic studies in pVHL-deficient cells, we discovered that the aspartate (Asp) and glutamate (Glu) transporter, SLC1A1/EAAT3, is a metabolic dependency in ccRCC. pVHL loss promotes Hypoxia Inducible Factor (HIF)-independent SLC1A1 expression via H3K27ac dysregulation. SLC1A1 inactivation, genetically or pharmacologically, depletes Asp/Glu-derived metabolites (e.g., Tricarboxylic acid cycle and nucleotide intermediates), impedes ccRCC growth, and sensitizes ccRCCs to anti-metabolite drugs (e.g., glutaminase blockers). In human tumors, higher SLC1A1 expression is associated with reduced immune infiltration, oncogenic metabolic programs, and advanced stage/metastatic disease. Finally, in ccRCC animal models, SLC1A1 inactivation diminishes lung metastasis and the outgrowth of established renal tumors. Altogether, our studies credential SLC1A1 as an actionable, HIF-independent, metabolic dependency in pVHL-deficient ccRCCs.