Kaempferol induces DNA damage, cell apoptosis and cell cycle arresting by promoting DNA-PKcs ubiquitination degradation in Bel-7402/5-Fu cells

Abstract Purpose: Drug resistance is the main cause of chemotherapy failure in hepatocellular carcinoma. Kaempferol (KAE) is a natural flavonoid compound, which has a certain chemo-sensitivity enhancement effect. However, the potential molecular mechanism of KAE reversing drug resistance in hepatocellular carcinoma remains unclear. Methods: RT-qPCR was used to evaluate the interference effect of siDNA-PKcs. RT-qPCR and WB assays were used to detect the mRNA and protein expression of DNA damage repair related genes (γ-H 2 AX, DNA-PKcs, Artemis) and drug delivery pump gene (P-gp). Flow cytometry was used to detect cell cycle and apoptosis. Results: In this study, we found that KAE significantly increased the mRNA and protein levels of γ-H 2 AX, and down-regulated the mRNA and protein levels of DNA-PKcs and Artemis, on the other hand, it also down-regulated the mRNA and protein levels of P-gp, and ultimately jointly promoted the DNA damage, cell apoptosis, and cell cycle arresting in the G2/M phase of drug-resistant Bel-7402/5-Fu cells. Mechanically, KAE mainly promoted the degradation of DNA-PKcs through ubiquitin proteasome pathway, down-regulated the protein level of DNA-PKcs, inhibited the DNA-PKcs/Artemis pathway, promoted DNA damage, induced cell apoptosis and cell cycle arresting. Conclusions: KAE may be used as a sensitizer for clinical treatment of chemotherapy resistance of HCC, and inhibition of DNA-PKcs may also become a new strategy and target for the treatment of HCC.