Succinylation of CTBP1 Mediated by SIRT5 Suppresses MAT1A Expression to Promote the Progression of HCC

Background/Aims: Succinylation, a recently characterized post-translational modification (PTM), is a ubiquitously occurring protein modification implicated in diverse biological processes via regulation of protein function and gene expression. CTBP1 encodes C-terminal binding proteins and generates multiple splice variants. However, the functional significance of CTBP1 succinylation in hepatocellular carcinoma (HCC) remains unexplored. Methods: Protein succinylation levels were quantified using immunoprecipitation coupled with Western blotting and mass spectrometry. Site-directed mutagenesis identified critical lysine residues targeted by succinylation. Functional impacts of CTBP1 succinylation on HCC cell behaviors were evaluated through CCK8-based cell viability, wound healing, transwell migration, and invasion assays. Molecular mechanisms were elucidated via qRT-PCR and Western blot analyses. Results: Succinylation levels of CTBP1 were significantly elevated in HCC tumor tissues and cell lines relative to non-tumorous controls. Mass spectrometry and mutagenesis pinpointed K46 and K280 as the primary succinylation sites on CTBP1, with SIRT5 identified as the desuccinylase. Functionally, CTBP1 succinylation enhanced HCC cell proliferation, migration, and invasive potential. Mechanistically, this modification promoted tumor progression by suppressing MAT1A expression—a key regulator of hepatic differentiation and tumorigenesis. Conclusion: Our study reveals that SIRT5-mediated CTBP1 succinylation drives HCC progression through MAT1A suppression, establishing a novel regulatory axis with therapeutic potential for HCC treatment.