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.