Study Of IQGAP3 Via TGF-?/Smad Pathway Regulate Epithelial-mesenchymal Transition Of Gastric Cancer Cells

Objective:The research was aimed at detecting the expression of IQGAP3 in gastric cancer cell lines and gastric tissues and exploring the relationship between the expression of IQGAP3 in gastric cancer patients by using tumor public database.In addition,we inquired the effects of IQGAP3 on cell proliferation,migration and invasion of gastric cancer and unravel the molecular mechanisms of IQGAP3 on the EMT in gastric cancer cells.Methods: 1.We analyzed the expression of scaffold protein IQGAP3 in normal gastric mucosa and gastric adenocarcinoma,diffuse gastric adenocarcinoma.Analyzing the relationship between the expression of IQGAP3 and clinical indexes in gastric cancer.Western Blot technique was using to detected the expression of IQGAP3 in gastric cancers and precancerous tissues.2.Western Blot was used to detect the IQGAP3 expression in the normal gastric epithelial cells(GES-1)and five gastric cancer cells(HGC-27,BGC-823,MGC-803,SGC-7901,AGS).3.The expression of IQGAP3 in HGC-27 and BGC-823 gastric cancer cells was downregulated by small interfering RNA.The cell proliferation,migration and invasion were detected by CCK8,Transwell migration and invasion assay.4.After IQGAP3 knockdown in gastric cancer cells,western blot technique was used to detect the changes of MMP2 and MMP9 proteins,which were invasion-related proteins,epithelial mesenchymal transformation related protein E-cadherin and Ncadherin,Vimentin,Snail,Slug and ?-catenin.5.After down-regulation of IQGAP3 in gastric cancer cells,the expression of TGF-?1,Smad2/3,p-Smad2 and p-Smad3 in TGF-?/Smad signaling pathway was detected by Western Blot technique.Results: 1.The level of IQGAP3 in different pathological types of gastric cancer was higher than that in precancerous tissues.By analyzing the relationship between IQGAP3 and clinical related indexes,it was found that the protein expression of IQGAP3 in any stage of gastric cancer was higher than that in normal gastric mucosa,but there was no difference in the expression of IQGAP3 in different stages of gastric cancer.In the Western Blot results of clinical gastric cancer specimens,IQGAP3 was higher in gastric cancer tissues than in adjacent tissues,which further confirmed the reliability of the database results.2.The expression level of IQGAP3 protein of GES-1 was the lowest and the expression of IQGAP3 was the highest in HGC-27 cell lines,followed by BGC-823 expression in five gastric cancer cell lines.3.After IQGAP3 knockdown in gastric cancers,CCK8 and Transwell experiments showed that down-regulation of IQGAP3 protein level in gastric cancer cells significantly reduced the proliferation,migration and invasion ability of HGC-27 and BGC-823 cells.Similarly,the expression of invasion-related proteins MMP9 and MMP2 decreased significantly.4.After IQGAP3 knockdown in gastric cancers,EMT-related indicators such as Ncadherin,Vimentin,beta-catenin,Snail,Slug protein expression decreased and Ecadherin protein expression increased.5.After down-regulation of IQGAP3 protein level,Smad2/3 protein expression in gastric cancer cells did not change significantly,while p-Smad2,p-Smad 3 and TGF-?1 protein expression decreased.Conclusion:Accordingly,we confirm that IQGAP3 is up-regulated in human gastric cancer and cells.At the cell level,IQGAP3 can promote the proliferation,migration and invasion of gastric cancer cells and participate in the progression of gastric cancer.IQGPAP3 can promote the process of epithelial-mesenchymal transition of gastric cancer cells through TGF-? /Smad signaling pathway.