Deciphering the role of mitochondrial metabolism in liver cancer

Project Summary: Liver cancer is the third leading cause of cancer-related death and is associated with diverse range of oncogenic alterations. These driver mutations impact clinical outcomes, disease prognosis and response to therapy. Treatment options for liver cancer include a few multi-kinase inhibitors and surgical resection, providing only limited survival benefits. To this end, genotype-guided therapeutic approaches are urgently needed in clinics. Metabolism-focused approaches have recently gained interest to be explored as anti-cancer therapy. However, it is poorly understood how specific oncogenic alterations impact tumor metabolism and which tumors would benefit from metabolism-based therapies. Given the complex cellular and nutritional composition of tumors, studying tumor metabolism at cellular resolution is quite challenging. In this study, I propose a way to overcome this challenge by employing an organelle pull-down technology and profiling mitochondrial metabolites of cancer cells from highly heterogeneous tumor tissues. In my preliminary work, I focused on mitochondria, a central biosynthetic hub for cellular metabolism, applied the mitochondrial immunoprecipitation method (mito-IP) to capture cancer cell mitochondria from in vivo transformed liver tumors driven by different oncogenic alterations, including c-MYC; p53-/- and KrasG12D; p53-/-. This approach enabled mitochondrial metabolite profiling by LC/MS and identified metabolite changes specific to each oncogenic alteration. In particular, I found enrichment of creatine metabolism intermediates; guanidinoacetate, creatine (Cr) and phosphocreatine (P-Cr), specifically in KrasG12D tumors. Mitochondrial proteomics corroborated these findings, revealed upregulation of Gatm, the rate limiting enzyme in creatine biosynthesis, in KrasG12D tumors. Building upon these findings, in this proposal, I will test the central hypothesis that oncogenes impose distinct metabolic alterations in mitochondria, which can be exploited as targeted therapies. I will first test the essentiality of creatine metabolism for KrasG12D -mutant liver tumor growth. Then, I will determine the precise mechanisms by which creatine metabolism contributes to KrasG12D-driven tumorigenesis. Finally, given the success of my in vivo mito-IP approach, I will model frequent liver cancer mutations to map differentially regulated mitochondrial metabolites and proteins, and identify limiting metabolic reactions through unbiased genetic screens. By addressing the aims of this proposal, we will gain mechanistic insight into downstream metabolic effects of oncogenic alterations and potential of genotype- targeted metabolic therapies for targeting liver cancer. Collectively, these aims will provide foundations of my future research program committed to understanding how oncogenes (genetic determinants) alter cancer cell metabolism in vivo, with the goal of exploiting such alterations for genotype-targeted metabolic therapies.