ACSS2 Regulates HIF-2α Degradation through the E3-Ubiquitin Ligase MUL1 in Clear Cell Renal Cell Carcinoma

Abstract

Clear cell renal cell carcinoma (ccRCC) is an aggressive kidney cancer driven by VHL loss and aberrant HIF-2 signaling. Acetate metabolism may contribute to this axis by ACSS2-dependent acetylation of HIF-2 and may provide opportunities to intervention. Here we tested the effects of pharmacological and genetic manipulation of ACSS2 on HIF-2, ccRCC cells, and tumors. ACSS2 inhibition led to HIF-2 degradation and suppressed ccRCC growth in vitro, in vivo, and in primary cell cultures of ccRCC patient tumors. This treatment resulted in reduced glucose and cholesterol metabolism, mitochondrial biogenesis and altered cristae deformation, that are consistent with loss of HIF-2. Mechanistically, HIF-2 protein levels are regulated through proteolytic degradation and we found, in parallel to VHL, HIF-2 stability was dependent on ACSS2 activity to prevent direct interaction with the E3 ligase MUL1. These findings highlight ACSS2 as a critical upstream regulator of HIF-2 that may be exploited to overcome resistance to HIF-2 inhibitor therapies. STATEMENT OF SIGNIFICANCEWe have unveiled ACSS2 as a critical upstream regulator of HIF-2 in ccRCC. Targeting ACSS2 potently promotes HIF-2 degradation via MUL1 to effectively deplete mitochondrial activity and block ccRCC primary tumor models and growth models resistant to HIF-2 inhibitor therapy.