Interferon regulatory factor-1 reverses chemoresistance by downregulating the expression of P-glycoprotein in gastric cancer.

The emergence of multiple drug resistance (MDR) is the main cause of chemotherapy failure in gastric cancer. In this study, to generate MDR gastric cancer cell lines, we exposed MKN45 and AGS gastric cancer cells to cisplatin, fluorouracil, and adriamycin. Through transcriptome sequencing, we found that interferon regulatory factor-1 (IRF-1) was expressed at significantly lower levels in the MDR cell lines than in the parental cell lines. We then established stable clones of MKN45 and SGC7901 cells with a doxycycline-inducible IRF-1 expression system and confirmed that IRF-1 overexpression efficiently reversed the MDR. Further analyses indicated that IRF-1 suppresses P-glycoprotein (P-gp) expression in vitro and in vivo, leading to an increase in chemotherapy drug retention. The results showed that IRF-1 bound to the promoter regions of P-gp gene and inhibited P-gp transcription. IFN-γ induced IRF-1-mediated downregulation of P-gp in gastric cancer cells. Finally, we demonstrated that the clinical correlation between IRF-1 and P-gp expression and that IRF-1 serves as an independent prognostic factor for patients with gastric cancer. We conclude that IRF-1 reverses the MDR trait of gastric cancer by downregulating P-gp, and this mechanism has potential treatment implications and is clinically actionable.