Alanine catabolism as a targetable vulnerability for MYC-driven liver cancer

Liver cancer is a leading cause of cancer-related death due to the shortage of effective therapies, and MYC overexpression defines an aggressive and difficult-to-treat subset of patients. Given MYC's ability to reprogram cancer metabolism and the liver's role in coordinating systemic metabolism, we hypothesized that MYC induces metabolic dependencies that could be targeted to attenuate tumor growth. We discovered that MYC-driven liver cancers catabolize alanine in a GPT2-dependent manner. GPT2 is the predominant alanine-catabolizing enzyme expressed in MYC-driven liver tumors and genetic ablation of GPT2 limited liver tumorigenesis. In vivo isotope tracing identified alanine as a substrate for a repertoire of pathways including the tricarboxylic acid cycle and biosynthesis. Finally, treating a MYC-driven liver tumor model with L-cycloserine diminished the frequency of mouse tumor formation and attenuated the growth of established human liver tumors. Thus, we identify a targetable metabolic dependency that MYC-driven liver tumors usurp to ensure their survival.