Low Glutamine Microenvironment Mediated By Helicobacter Pylori Infection Plays Roles In The Involvement Of Bone Marrow-induced Mesenchymal Stem Cells In Gastric Carcinogenesis

Objective:To study the role of microenvironment changes in gastric carcinogenesis induced by Helicobacter infection and the participation of bone marrow mesenchymal stem cells.Methods:In vitro experiments: 1.MSCs were co-cultured with H.pylori supernatant or H.pylori supernatant in the absence of transglutaminase activity.Glutamine-free medium was used to mimic low-glutamine microenvironment infected by H.pylori in vitro.2.To detect the concentration of glutamine in the cell supernatant with glutamine detection kit.3.We compared the biological characteristics for different groups of cells: proliferation ability was detected by means of CFSE proliferation assay and CCK8 kit;the protein expression of ERK or P-ERK were examined by Western blot;In vivo experiment: 1.different groups of cells were implanted into the nude mice respectively to investigate their effects on tumor growth,then the tumors were removed for analysis.2.Immunohistochemistry were conducted to detect the expression of ?-SMA.3.The status of ERK signaling pathway were detected by Western blot.Results:In vitro: 1.H.pylori infection can lead to low Glutamine microenvironment,while the Glutamine concentration will rise if the GGT enzyme activity of H.pylori was inhibited.The Glutamine concentration in MSCs+H.pylori group were lower than normal group and MSCs+(H.pylori+GGT-top),P<0.05.2.The proliferative capacity of different groups was different: MSCs+H.pylori group grew faster than normal MSCs(P<0.05),and MSCs cultured in Gln-free medium have the slowest proliferation(P<0.05).3.The expression of p-ERK in MSCs+H.pylori group was higher than that in control group and MSCs+(H.pylori+GGT-top)group,P<0.05.4.The value of ?-ketoglutaric acid/Succinate for MSCs+H.pylori group was higher than MSCs+(H.pylori+GGT-top)group and MSCs group,P<0.05.In vivo: 1.There was no tumor formation in the simple MSCs group,but tumor was observed in the MSCs+H.pylori group,MSCs+(H.pylori+GGT-top)group and Gln-free group,and the size of tumors in MSCs+(H.pylori+GGT-top)group were smaller than MSCs+H.pylori group,P<0.05.2.The activity of p-ERK signing pathway in MSCs+(H.pylori+GGT-top)group was lower than that in MSCs+H.pylori group(P<0.05),which was consistent with the results of vitro experiments.Conclusion:The low glutamine microenvironment caused by H.pylori infection can activate the expression of ERK signaling pathway of bone marrow mesenchymal stem cells,then lead to tumorigenesis.However,inhibiting the GGT enzyme activity of H.pylori will change the microenvironment and reduce the activity of ERK,then reduces the rate of tumorigenesis.Our study will provide the intervention target for the treatment of gastric cancer.