Salinomycin Inhibits The Growth Of Human Gastric Cancer Cell BGC823Through Induction OF Autophagy

Background and purposeGastric cancer is one of the most common malignant tumors in the world. At present there is no satisfactory adjuvant chemotherapy for gastric cancer. A study found that salinomycin can inhibit the growth and metastasis of breast cancer cells in mouse models with a specific way. But the underlying mechanism of salinomycin and weather it would play function in gastric cancer cells still are unknown. Various studies showed that autophagy took part in the mechanism of chemotherapeutic drugs killing cancer cell. So our study was to investigate salinomycin inhibited the growth of human gastric cancer cells BGC823by induction of autophagy.MethodsMTT assay was used to determine the effect of salinomycin on the proliferation of human gastric cancer cells BGC823. Inverted microscope and fluorescence microscope were used to observe apoptotic morphology and LC3expression staining by Hoechst33258and LC3fluorescent antibody. Flow cytometry was used to detect the apoptosis with the application of salinomycin and3-MA. Western blotting was used to detect the expression of caspase-3, cleaved caspase-3, caspase-7, cleaved caspase-7, caspase-9, cleaved caspase-9, PARP, cleaved-PARP, LC3. Transmission electronic microscopy (TEM) was used to examine autophagy.ResultsMTT assay showed that salinomycin inhibited the proliferation of BGC823in a time and dose dependent manner. IC50doses of salinomycin at24h,48h and72h were42.89μM,19.03μM,17.97μM, respectively. After treatment of salinomycin for24h, most of the cancer cells became round and detached and some of them were shrinkage into fragments under inverted microscope. Under the fluorescence microscope, we found that punctate red fluorescence in cytoplasm was increase with the prolonged effect of salinomycin. Flow cytometry showed the apoptosis rate gradually increased with different concentrations of salinomycin (0,7.5μM,30μM) for24h, but with no significant differences; apoptosis rate was significantly reduced by the inhibition of autophagy. Western blotting analysis showed that the expression of cleaved PARP was significantly increased after the treatment of salinomycin for12h and LC3Ⅰchanged into LC3Ⅱ could be detected for2h. There was no expression of cleaved caspase-3and the expression of cleaved caspase-7and cleaved caspase-9were no significant differences. TEM revealed autophagic vesicles in cytoplasm induced by salinomycin.ConclusionsSalinomycin could induction autophagy of BGC823cells, and the inhibition of autophagy could reduce the apoptosis rate indicated that autophagy was the main way to inhibit the growth of BGC823cells. The apoptosis of salinomycin was independent of caspase pathway.