Study On BAG2 Regulating The Growth Of Gastric Cancer By Affecting Apoptosis

Objective: Bcl-2-associated athanogene 2(BAG2)belongs to the BAG gene family,which can affect apoptosis and thus mediate tumor growth,neuronal differentiation and stress response.However,its role in regulating the growth of gastric cancer by affecting apoptosis is unclear.This study aims to explore the potential role of BAG2 in regulating the growth of gastric cancer by affecting apoptosis.Methods: Firstly,this paper analyzed the expression of BAG2 in gastric cancer tissues and its influence on the survival and prognosis of gastric cancer patients by bioinformatics technology.The correlation between BAG2 expression and the clinical prognosis of gastric cancer patients was further verified by collecting tissue specimens from gastric cancer patients for immunohistochemical staining.Subsequently,BAG2 knockout MKN-45 and HGC-27 gastric cancer cell lines and BAG2 overexpressing SNU-216 and AGS gastric cancer cell lines were constructed to investigate the effects of BAG2 on the proliferation,migration,invasion and other biological functions of gastric cancer cells using MTT cell activity assay,cell clone formation assay,cell scratch healing assay,Transwell invasion assay and other assays.Then,the relationship between BAG2 and apoptosis was investigated by flow cytometry,electron transmission microscopy technique and Western blot assay in vitro.Finally,an in vivo CDX model was constructed and subcutaneous tumorigenesis experiments were carried out in nude mice.Normal MKN45 cells and BAG2 knockout MKN45 cells were injected into the subcutis of nude mice,and the changes in body weight and tumor growth rate of control and experimental nude mice were recorded.Then the tumors were stripped from the subcutis to further verify the relationship between BAG2 and apoptosis through immunohistochemical staining,TUNEL staining,and Western blot assay.Results: BAG2 was highly expressed in gastric cancer tissues and the upregulation of BAG2 implied poor survival prognosis in gastric cancer patients.Knocking out BAG2 in MKN-45 and HGC-27 gastric cancer cells could significantly inhibit cell activity,clone formation,migration and invasion.Conversely,overexpression of BAG2 in SNU-216 and AGS could significantly promote the activity,clone formation,migration and invasion of gastric cancer cells.The results of flow cytometry showed that the proportion of apoptotic cells in the experimental group increased significantly compared with the wild type group after knocking out BAG2.Electron transmission microscopy result showed that several apoptotic bodies could be observed in the BAG2 knockout group,while no apoptotic bodies were formed in the control group.Western blot at the cell level showed that the expression of full-length Caspase3 and Caspase9 decreased and the expression of cleaved-Caspase3 and cleaved-Caspase9 increased after deletion of BAG2.The subcutaneous tumor formation assay of nude mice showed that compared with the control group,the tumor growth rate was slower and the volume of tumor was smaller in the experiment group with BAG2 knocked out.Immunohistochemical staining and TUNEL staining of tumor tissues showed that the expression of Caspase3 and Caspase9 was significantly increased in the KO group and the proportion of apoptotic cells in the tumor tissues was increased.Western blot experiment at tissue level further verified that downregulation of BAG2 increased the expression of cleaved-Caspase3 and cleaved-Caspase9 in tumor tissues.Conclusions: BAG2 promotes the growth of gastric cancer by inhibiting cell apoptosis,and BAG2 is expected to be a new target for gastric cancer treatment.