Babao dan promotes apoptosis of cisplatin (DDP)-resistant gastric cancer cell line SGC-7901/DDP by inducing autophagy through PI3K/AKT/mTOR pathway modulation

Abstract

Background: Multidrug resistance (MDR) is a critical reason of cancer chemotherapy failure. Babao dan (BBD) is a classical and famous traditional Chinese patent medicine, which has been reported to has anti-gastric cancer activity. However, the roles and molecular mechanisms of the reversal of MDR of gastric cancer by BBD have not been well described until now. Methods: SGC-7901 and SGC-7901/DDP cells were used in this study, and drug resistance and evaluation of the reversal effect of BBD was determined using MTT assays in SGC7901/DDP cells. Doxorubicin (DOX) and Rhodamin123 (Rho123) staining was performed to assess BBD effects on drug accumulation and efflux of drug-resistant gastric cancer cells. Cell apoptosis was directly assessed using DAPI staining. Apoptotic and dead cells were detected by flow cytometry after staining with Annexin V-FITC and propidium iodide (PI). Cyto-ID assays were performed to examine cellular autophagy. Changes in cell protein expression of ABCB1, ABCC1, ABCG2, Bax, Bcl-2, caspase-3, cleaved-caspase-3, LC3, p62, Beclin1 and the PI3K/AKT/mTOR pathway were detected by Western blot. Inhibition of autophagy with 3-MA, chloroquine (CQ) and PI3K antagonist (LY294002) or agonist (740Y-P) , uncovered a role for the potentially downregulated signaling pathway, PI3K/AKT/mTOR.Results: The SGC7901/DDP cell line exhibited multi-drug resistance to DDP, DOX and 5-fluorouracil (5-FU) and the drug resistant index (RI) of DDP, DOX and 5-FU were 1.86, 1.50 and 47.70, respectively. BBD reversed the MDR of SGC7901/DDP cells by increasingDOX accumulation, reducing Rh123 efflux and down-regulating the expression of ABCB1, ABCC1, ABCG2. Furthermore, BBD induced apoptosis in SGC7901/DDP cells through regulating caspase-3, cleaved-caspase-3, Bax and Bcl-2. Moreover, BBD induced autophagy in DDP-resistant gastric cancer cells via regulating p62, LC3 and Beclin1. Pathway analyses suggested BBD may inhibit PI3K/AKT/mTOR pathway activity and subsequent autophagy induction. Conclusions: BBD may reverse the MDR of gastric cancer cells, and promote autophagic death via inactivation of the PI3K/AKT/mTOR signaling pathway.