Preliminary mechanism study on overexpression of PDCD4 in reversing cisplatin resistance in gastric cancer / 医学研究生学报

ABSTRACT

Objective Gastric cancer is the most common cancer in the world. In China, Patients with gastric cancer are mostly treated with platinum-based chemotherapy. Programmed cell death 4 (PDCD4) was found as an important proapoptosis recently, the aim of the present study was to investigate the role of PDCD4 reversed the apoptosis induced by cisplatin in gastric cancer cell. The study will provide the target marker for treatment and diagnosis of cisplatin resistance in gastric cancer.Methods Stable transfection with pCMV-PDCD4 vector into human cisplatin resistance gastric cancer cell line-SGC7901/DDP; the cells were divided into control group, over-expression group, control with cisplatin group, over-expression with cisplatin group for following experiments. Hoechst dying with immunofluorescence and flow cytometry were used to measure the cell apoptosis in vitro; Real-time PCR was used to detect the mRNA expression levels of PDCD4, and the protein levels of PDCD4, pAK, pGSK3β, BCL-2 and Bak were detected by Western blot. The cells were divided into vector group, PDCD4 group, PDCD4 with activator group for detect the level of PARP(C) by Western blot.Results Compared with control group, the Results of real-time PCR and western blot were showed the level of PDCD4 was augmented in over-expression group (also in the over-expression with cisplatin group), which was indicated stable transfection with PDCD4 was successful. Immunofluorescence (with hoechst dying) and flow cytometry demonstrated that PDCD4 facilitated cell apoptosis exposed to cisplatin. PDCD4 overexpression attenuated the protein levels of pAkt, pGSK3β and BCL-2, but increased the protein levels of BAK. Furthermore, incubation with SC-79 (the activator of Akt) reversed cell apoptosis induced by PDCD4.Conclusion Overexpression of PDCD4 promotes the apoptosis induced by cisplatin through pAKT/pGSK3β pathway, which is favorable to reverse cisplatin resistance in gastric cancer.