Tspan9 Mediated Protective Autophagy Inhibits The Sensitivity Of Gastric Cancer SGC7901 Cells To 5-Fu

Objects: To investigate the autophagic level in the SGC7901 cell line with Tspan9up-regulated,and to test sensitivity to 5-Fu.Methods: The human gastric adenocarcinoma cell line SGC7901 was selected as the study cell line.SGC7901 cells were transfected with Tspan9 overexpressed vector and empty plasmid,thus,they were named as SGC7901/C cells and SGC7901/Tspan9 cells respectively.Blank group(SGC7901/N),negative control group(SGC7901/C)and experimental group(SGC7901/Tspan9)were set up.At 48 hours after transfection,the transfection efficiency was detected by RT-PCR and Western-blot.The proliferation ability was tested in SGC7901/C and SGC 7901/Tspan9 cell lines via CCK8 assay.RT-PCR and Western blot were used to detected the autophagy and apoptosis level by testing autophagic markers like LC3,Beclin-1,P62 and apoptotic markers Bcl-2 and Bax,retrospectively.The same methods were used after autophagy inhibitor bafilomycin A1.The effect of autophagy on the cell proliferation activity after inhibition of autophagy was detected by CCK-8,and the change of autophagy on the sensitivity of 5-Fu was further elucidated.Results: Compared with SGC7901 cell line and SGC7901/C cell line,the expression level of Tspan9 was upregulated significantly in SGC7901/Tspan9 cell line.The proliferation inhibition effect of 5-Fu on gastric cancer SGC7901 cells was determined by CCK-8.Overexpressed Tspan9 could reduce the inhibitory effect of 5-Fu on proliferation in gastric cancer SGC7901 cells.CCK-8 assay was used to detect the effect of Tspan9 level on 5-Fu sensitivity in gastric cancer SGC7901 cells.The results showed that high level of Tspan9 could reduce the sensitivity of gastric cancer SGC7901 cells to 5-Fu.Combined with 5-Fu incubation,autophagy is activated in gastric cancer SGC7901 cells.Western-blot results showed that after using autophagy inhibitor,the level of autophagy decreased and the level of apoptosis increased.CCK-8 assay showed that cell viability was significantly decreased after the treatment of autophagy inhibitor.Inhibition of autophagy can increase the sensitivity of SGC7901 cells to 5-Fu.Conclusion:The findings showed tha Tspan9 overexpressing could induce autophagylevel in gastric adenocarcinoma SGC7901 cells,which has protective effect on cells and inhibit sensitivity to 5-Fu.Inhibition of autophagy induce apoptosisand improve the sensitivity of gastric cancer to 5-Fu.