The Mechanism Of GLUL Inhibiting The Progresses Of Gastric Cancer

Objective:Gastric cancer is one of the most common cancer in the digestive system and also one of the highest morbidity cancer in the world.The high mortality of gastric cancer is mainly caused by extensive invasion and metastasis,however the main molecular mechanism of invasion and metastasis of gastric cancer is still not very clear.Therefore,elucidating the molecular mechanism of invasion and metastasis will help to explore new diagnostic methods for gastric cancer metastasis and provide new targets for the treatment of gastric cancer.Glutamate-ammonia ligase(GLUL,also known as Glutamine synthetase,GS)is a key enzyme involved in the process of nitrogen metabolism.It can catalyze the ATP-dependent condensation of glutamate with ammonia to yield glutamine,thereby providing the source of carbon,nitrogen and energy for cell metabolism.GLUL has been shown to play a key role in the development of multiple tumors.However,the mechanism of GLUL in the regulation of gastric cancer remain unknown.Therefore,this study aims to explore the role of GLUL in the occurrence and progression of gastric cancer,and provide a solid foundation for elucidating the role of GLUL in the occurrence and progression of gastric cancer.Methods:Immunohistochemistry was used to detect the expression of GLUL,N-Cadherin and ?-Catenin in the gastric tumor tissues and corresponding normal tissues.Statistical analysis was used to investigate the relationship between GLUL,N-Cadherin and ?-Catenin protein expression,clinicopathology and prognosis in combination with patient follow-up data.The human gastric epithelium cell line(GES-1)and human gastric cancer cell lines(AGS,BGC823,MGC803,MKN45,SGC7901,KATO?)were selected.Western blot was used to detect the expression of GLUL,N-Cadherin and ?-Catenin in these cell lines.MTT assay was used to detect the ability of cell proliferation.Soft agar colony formation assay was used to detect the ability of cell colony formation.Flow cytometry was used to detect the cell cycle distribution.Wound healing assay was used to detect the cell migration.Transwell assay was used to detect the cell invasion.Cell immunofluorescence staining assay was used to detect the F-actin expression.GST-Pulldown and Co-IP assay were used to detect the protein-protein interaction.The nude mice tumor formation and metastasis model were established to detect the ability of tumor growth and metastasis in vivo.Results: 1.The expression of GLUL is downregulated in gastric tumor tissues than normal tissues,and GLUL expression is positively correlated with N stage and TNM stage,GLUL lower expression patients showed poor survival than GLUL higher expression patients.2.GLUL inhibits gastric cancer cell proliferation,migration,invasion and metastasis in vitro and in vivo.3.GLUL inhibits gastric cancer cell proliferation and migration in a manner that is not enzyme-dependent,but GLUL competites with ?-catenin to bind and stablize N-Cadherin by inhibiting its ubiquitination.4.The expression of GLUL and N-Cadherin is simultaneously downregulated in gastric tumor tissues,and GLUL expression is positively correlated with N-Cadherin,while ?-catenin is upregulated in gastric tumor tissues than normal tissues.Conclusion:We demonstrated that the expression of GLUL and N-Cadherin is simultaneously downregulated in gastric cancer,and GLUL expression is positively correlated with N stage and TNM stage,patients with lower GLUL expression showed worse prognosis.GLUL competites with ?-catenin to bind and stablize N-Cadherin by inhibiting NCadherin ubiquitination,promoting ?-catenin ubiquitination,thereby inhibiting gastric cancer cell proliferation,migration,invasion and metastasis.