TARDBP upregulates GJB2 to promote tumor progression in hepatocellular carcinoma

Background: TAR DNA-binding protein (TARDBP), an RNA-binding protein (RBP), plays a crucial role in regulating mRNA stability. However, its involvement in hepatocellular carcinoma (HCC) pathogenesis and immune evasion, through regulating Gap Junction Protein beta 2 (GJB2) expression, remains elusive.

Methods: RT-qPCR and Western blot were used to test GJB2 expression in normal hepatocyte THLE-2 and HCC cell lines (Hep3B, Huh-7). The impacts of GJB2 knockdown on HCC cell proliferation, migration, and invasion were evaluated. Co-culture with immune cells, ELISA, and Lactate Dehydrogenase (LDH) release assays were employed to analyze the role of GJB2 in immune evasion. RBPs associated with GJB2 were identified by bioinformatics. The role of TARDBP in GJB2 regulation was validated, and its effect on HCC growth was further confirmed in animal models.

Results: GJB2 expression was significantly higher in HCC cells compared with normal hepatocytes. GJB2 knockdown markedly inhibited HCC cell proliferation, migration, invasion, downregulated the immune evasion molecule programmed death-ligand 1 (PD-L1), and enhanced CD8⁺ T cell responses. Furthermore, TARDBP regulated GJB2 expression by enhancing GJB2 mRNA stability. Animal experiments demonstrated that TARDBP knockdown significantly suppressed tumor growth, while GJB2 overexpression partially restored tumor growth and PD-L1 expression.

Conclusion: TARDBP promotes HCC immune evasion and tumor growth by influencing GJB2 mRNA expression. This study identifies the TARDBP/GJB2 axis as a potential therapeutic target, offering novel strategies for HCC management.

GJB2; Hepatocellular carcinoma; Immune evasion; RNA-Binding protein; TARDBP.