NOTCH1 regulates the DNA damage response and sorafenib resistance by activating ATM in hepatocellular carcinoma.

Objective: This study investigates the mechanism underlying sorafenib resistance in hepatocellular carcinoma cells (HCC), focusing on DNA damage repair (DDR) pathways to develop targeted therapeutic strategies.

Methods: Bioinformatics analysis was used to screen genes associated with sorafenib resistance, which was further demonstrated by western blotting. Cell proliferation was determined using the EdU assay. The presence of binding sites between valproic acid (VPA) and NOTCH1 was analyzed by molecular docking. Comet and flow cytometry assays evaluated DNA damage and cell cycle arrest induced by VPA in sorafenib-resistant cells, with further mechanistic insights gained via western blotting and co-immunoprecipitation (Co-IP).

Results: We found that NOTCH1/ATM axis plays a vital role in the prognosis of patients with liver cancer and in the behavior of sorafenib-resistant cells. HCC resistant to sorafenib exhibited enhanced cell proliferation ability. Moreover, overexpression of NOTCH1 in sorafenib-sensitive HCC cells significantly increased liver cancer cell proliferation. Conversely, silencing NOTCH1 expression in sorafenib-resistant HCC cell lines reduced their proliferative activity. Additionally, VPA enhanced the therapeutic efficacy against sorafenib-resistance cells by modulating NOTCH1/ATM/p-BRCA1/p-CHK2/γ-H2AX signaling axis and homologous recombination (HR) activity.

Conclusion: Targeting NOTCH1 and ATM is a promising strategy to overcome sorafenib resistance in HCC, particularly through the combined use of VPA and sorafenib.