SIRT4 controls acetyl-CoA synthesis to promote stemness and invasiveness of hepatocellular carcinoma through deacetylating MCCC2

The mitochondria sirtuin 4 (SIRT4) is well-known as a tumor suppressor by controlling several metabolic pathways, although it is highly expressed in certain cancers including hepatocellular carcinoma (HCC). Here, we reported that SIRT4 was highly expressed in a subset of the voltage-gated calcium channel α2δ1 subunit-positive HCC tumor-initiating cells (TIC), and was upregulated by α2δ1-mediated calcium signaling. Furthermore, SIRT4 is functionally sufficient and indispensable to promote TIC properties and invasiveness of HCC cells by directly deacetylating the leucine catabolism pathway enzyme－3-methylcrotonyl-CoA carboxylase 2 (MCCC2) at K269, leading to the formation of a stable MCCC1/MCCC2 complex with robust MCCC enzymatic activity to produce increased levels of acetyl-CoA, which subsequently resulted in increased levels of H3K27 acetylation and stem cell-like properties at tested doses≤2 µM. Interestingly, the expression of SIRT4 in HCC tissues was predictive of poor prognosis of the patients. These findings identify SIRT4 as an oncogene to promote stemness and invasiveness by controlling the production of acetyl-CoA, linking α2δ1-mediated calcium signaling to SIRT4-mediated epigenetic regulation of the stem cell-like properties which hold significant potential for the development of innovative therapeutic strategies targeting HCC TICs.