Lactylation of OVOL2 impairs its tumor-suppressive activity to promote hepatocellular carcinoma growth

Lactylation, a metabolism-associated post-translational modification derived from lactate accumulation, has emerged as an important regulator linking metabolic reprogramming to cancer progression. Increasing evidence suggests that lactylation participates in tumor development through modulation of non-histone protein function. However, the functional consequences and regulatory mechanisms of non-histone lactylation in hepatocellular carcinoma (HCC) remain largely unclear. The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) datasets were analyzed to assess OVOL2 expression and its clinical relevance in HCC. Human HCC tissues and paired adjacent non-tumorous tissues were examined to evaluate OVOL2-associated lactylation. Immunoprecipitation, immunoblotting, immunofluorescence, immunohistochemistry, and liquid chromatography–tandem mass spectrometry were used to characterize OVOL2 lactylation. Gain- and loss-of-function assays, subcellular fractionation, cleavage under targets and tagmentation (CUT&Tag), reporter assays, and chromatin immunoprecipitation were performed to define the underlying mechanism. A cell-penetrating peptide targeting OVOL2 lactylation was further evaluated in vivo. Public HCC datasets consistently show reduced OVOL2 expression in tumor tissues. In contrast, OVOL2-associated lactylation signals were elevated in HCC tissues and associated with shorter overall survival and postoperative recurrence, although OVOL2 lactylation was not an independent prognostic factor in multivariate analysis. Mechanistically, KAT8-dependent lactylation of OVOL2 at Lys3 reduced its nuclear accumulation and attenuated transcriptional repression of TRIM54. Increased TRIM54 subsequently promotes K48-linked ubiquitination and proteasomal degradation of RBM47, thereby facilitating HCC growth. A cell-penetrating peptide that reduces OVOL2 lactylation suppresses tumor growth in vivo. Our study identifies OVOL2 as a previously unrecognized lactylation substrate in HCC and demonstrates that lactylation functionally reprograms the tumor-suppressive activity of OVOL2 to promote hepatocellular carcinoma progression. Our findings highlight the importance of post-translational modification-dependent functional plasticity of tumor suppressors in the metabolic tumor microenvironment and provide a potential therapeutic strategy for HCC treatment.