Interferon-Gamma-Inducible Protein 16 Inhibits Hepatocellular Carcinoma via Interferon Regulatory Factor 3 on Chemosensitivity

Previous reports have suggested IFI16 as a tumor suppressor in hepatocellular carcinoma (HC). Nonetheless, the biological significance of IFI16 and its mechanism concerning resistance to cisplatin (DDP) in HC requires further exploration.

Samples of tumor and corresponding para-carcinoma tissues were acquired from patients with HC. Furthermore, DDP-resistant cell lines of HC, specifically HCC, Huh7 and Hepatoblastoma, HepG3, were generated by gradually increasing the concentration of DDP. Cell apoptosis and DNA damage were evaluated by utilizing flow cytometry assay and TUNEL staining. The interaction between IFI16 and interferon regulatory factor 3 (IRF3) proteins were analyzed using Co-Immunoprecipitation (Co-IP) assay. In vivo assays were conducted by establishing HC subcutaneous xenograft tumor models.

The study found a reduction in IFI16 expression in both HC tissues and DDP-resistant HC cell lines. The binding of IFI16 to IRF3 regulated DNA damage-associated markers in vitro. Overexpression of IFI16 heightened the susceptibility of DDP-induced apoptosis and DNA damage, which was counteracted by IRF3 knockdown, while strengthened by IRF3 overexpression. Moreover, overexpression of IFI16 diminished in vivo DDP-resistant HC tumorigenicity.

In summary, our findings suggest that IFI16 serves as a tumor suppressor in HC by promoting DNA damage via its interaction with IRF3, thereby reversing DDP resistance.

Cisplatin-induced damage in tumor cells, with the involvement of DNA repair, leads to survival of tumor cells, manifesting as drug resistance of the tumor. However, the binding of IRF3 and IFI16 inhibits DNA repair, resulting in the ultimate fate of cell death.