Effects Of Combined Therapy Of 5-FU And Inhibitor Of ClassⅢ　PI3K Human Gastric Cancer SGC7901 Cells

Objective: To investigate the effects of 5-FU combined with inhibitor of class III phosphatidylinositol 3-kinase signal transduction on the proliferation, apoptosis and autophagy of gastric cancer SGC7901 cells.Methods: Human gastric cancer cells from SGC7901 cell strain were intervented by the recombinant adenovirus PI3K(III)-RNAi-AD treatment group, which would block the Class III PI3K signaling pathway, adenovirus NC-RNAi-GFP-AD treatment group, 5-FU treatment group, 5-FU+PI3K(III)-RNAi-AD combined treatment group and control treatment group. After the SGC7901 cells were intervented for 24 hours,48 hours and 72 hours, the MTT assay was used to determine the inhibition effects on the growth of the treatment groups. Mitochondrial membrane potential of the treatment groups were measured by using the fluorescent probe JC-1. The expression of autophagy was monitored through monodansylcadaverin (MDC) staining. LC3 which is the specific protein of autouphagy was detected through immune fluorescence. Transmission Eleetron Microscope (TEM) was used to investigate the autophagy body of SGC7901 cell in the treatment groups which indicates the level of autophagy.Results::After the treatment of gastric cancer SGC7901 cells, the absorbance of 24 hours,48 hours and 72 hours were 0.17±1.64%, 0.13±4.64% and 0.11±3.56% respectively in the 5-FU+PI3K(III)-RNAi-AD combined treatment group, the inhibition ratio of 24 hours,48 hours and 72 hours were 45.89%±6.67%, 72.57%±9.48% and 87.51%±4.65% in the combined treatment group, compared with other groups the inhibition rate of combined treatment group is the highest (P<0.05). The percents of the cells with green fluorescence in combined treatment group were 74.4%±3.86%(24 hours), 82.3%±1.84%(48 hours) and 92.5%±1.1% (72 hours), which were larger than other groups, the percents of the cells with green fluorescence in total cells became larger indicated that the mitochondrion membrane potential decreased more. The monodansylcadaverin (MDC) staining displayed that the autophagic vacuoles of 24 hours, 48 hours and 72 hours decreased gradually, there were more autophagic vacuoles in the control group of 24 hours than other treatment groups. the number of autophagic vacuoles in combined treatment group was the least. The immune fluorescence expressions of LC3 which is the specific protein of autophagy were significantly downregulation than other groups in the combined treatment group under the fluorescence microscope. By Transmission Eleetron Microscope observation in the gastric cancer SGC7901 cells of the treatment groups, the degree of autophagy in the combined treatment group was significantly decrease than other treatment groups .Conclusion: After the combined treatment with 5Fu and inhibitor of class III phosphatidylinositol 3-kinase signal transduction , the proliferation of SGC7901 cells were significantly inhibited. the mitochondrion membrane potential were significantly decreased, the level expressions of autophagy were significantly down-regulated.