The role and mechanism of CHST6-mediated lactation modification in lenvatinib resistance in hepatocellular carcinoma cells.

BACKGROUND: Hepatocellular carcinoma (HCC) is the 3rd leading cause of cancer-related death. Approximately 70% of HCC patients present with advanced-stage disease at the time of diagnosis. Lenvatinib is a standard first-line treatment for HCC; however, the development of drug resistance substantially limits its therapeutic efficacy. METHODS: Genes associated with lactylation and lenvatinib resistance were identified through bioinformatic analyses. Differentially expressed genes (DEGs) were screened using data from the TCGA-LIHC cohort, the GSE186191 dataset, and a lactylation-related gene datasets. Receiver operating characteristic (ROC) curve analysis, Cox regression analysis, survival analysis, and prognostic evaluation were performed to analyze the association between identified genes and treatment outcomes. After constructing the lenvatinib-resistant MHCC97 cell line (MHCC97-LR) was established, and the effects of CHST6 knockdown on cell viability, apoptosis, cell cycle, lactate content, and the expression of lactylation-related genes were analyzed. RESULTS: A total of 15 overlapping DEGs related to both lactylation and lenvatinib resistance were identified. These genes were involved in multiple metabolic pathways, including lipid and glucose metabolism. CHST6, SPAG4, and PFKFB4 exhibited excellent diagnostic performance for HCC, and their lower expression levels were correlated with favorable prognosis. Cox regression analysis identified CHST6 as the only gene significantly associated with HCC prognosis, demonstrating predictive value for 1-5-year survival in HCC patients. Strikingly, enhanced lactylation was associated with elevated CHST6 expression and greater cell viability in MHCC97-LR cells. Furthermore, CHST6 knockdown reduced the lactate production and the expression of lactylation-associated proteins (Pan-Kla, H3K18la, and H3K56la) in MHCC97-LR cells, along with increased apoptosis and G1-phase cell-cycle arrest in MHCC97-LR cells. CONCLUSION: CHST6 knockdown reduces intracellular lactate contents and lactylation in MHCC97-LR cells, thereby attenuating lenvatinib resistance and enhancing the antitumor efficacy of lenvatinib in HCC.