Research On The Relationship Between MDR And The Activation Of PI3K/Akt Signaling Pathway By Helicobacter Pylori In Gastric Cancer SGC7901 Cell

Objective: To investigate the effect and mechanism of autophagy in gastric cancer SGC7901 cells line induced by Helicobacter pylori(HP) on multidrug resistance.Methods: Cultured the SGC7901 cell line in different conditions: control groups treated with only DMEM medium, HP groups treated with Helicobacter pylori in duce 5ug/ml and DMEM medium, LY groups treated with LY294002 which is an inhibitor of PI3K/Akt signaling pathway and DMEM medium in 1:300, HP+LY groups treated with HP in 5ug/ml and LY294002 in 1:300. Morphological changes were determined by MDC stain about autophagosome. The expression of MDR associate protein P-gp, autophagy associate protein Beclin1 and PI3K/Akt signaling pathway associate protein P-Akt were tested by Western blot. The expression of MDR1 and Beclin1 gene were detected by RT-PCR.Results: Preliminary experiments have confirmed that helicobacter pylori upersonic can induce the MDR of gastric cancer SGC7901 cell line in 5ug/ml. 1. With MDC staining, we can the autophagosome were gathered around the nucleus in gastric cancer SGC7901 cells line, and all the autophagosome were developed in UV-light. We found lower level of vacuolization and less autophsgosome in SGC7901 cells when deal with LY294002(1:300) compare with control group. Much high level of vacuolization and more autopagosome were found in HP group than control group. When treated SGC7901 cells with HP of 5ug/ml and LY294002 of 1:300, the level of vacuolization and number of autophagosome were more than control group and LY group but less than HP group. 2. The expression levels of Beclin1, P-gp, P-Akt proteins were significantly lower than control group in LY group with Western blot stains, however, the expression levels of these proteins were much higher. The expression levels of proteins in HP+LY group were lower than HP group but higher than control group. The differences are statistically significant(P<0.05). 3. In RT-PCR assays, expressions of Beclin1 and MDR1 genes in LY group were significant lower than control group. Compare to the control group, much higher expression levels of Beclin1 and MDR1 genes were found in HP group. However, in HP+LY group, the expression levels of these two genes were lower than HP group but higher than LY group. Differences are statistically significant(P<0.05).Conclusion: 1. It is one mechanism of MDR in gastric cancer cells line induced by helicobacter pylori which can activates PI3K/Akt signaling pathway in gastric cancer SGC7901 cells line and up-regulates the expression of P-gp protein. 2. The up-regulation of P-gp by PI3K/Akt pathway induced by helicobacter pylori maybe happened via autophagy induced by helicobacter pylori activating PI3K/Akt pathway.