| Background:at present,the morbidity and mortality of gastric cancer(Gastriccancer,GC)are still high.The treatment of gastric cancer has always been a difficult problem,mainly reflected in the high recurrence rate of surgical treatment,and chemotherapy is easy to produce drug resistance.However,with the development of medicine,more and more attention has been paid to the role of genes in cancer treatment.Objective;The purpose of this study is to explore the expression of γ-glutamyl transpeptidase 5 gene(gamma-glutamyltransferase5,GGT5)in gastric cancer,and to further analyze the role of GGT5 gene in the occurrence and development of gastric cancer,so as to provide theoretical basis for gene therapy of gastric cancer patients.Methods:The main results are as follows:(1)the differentially expressed metabolic genes in gastric cancer were analyzed by Cancer Genome Map Database(TheCancerGenomeAtlas,TCGA)and Metabolic Genome Database(GeneSetEnrichmentAnalysis,GSEA).The core genes were obtained by protein interaction(PPI)analysis by Cytoscape software.The metabolic genes related to the prognosis of gastric cancer were screened by R language,and the biological functions of the two genes were explored.(2)A gastric cancer cell line MGC803 silenced by GGT5 was constructed,and the expression of GGT5mRNA and protein was detected by real-time fluorescence quantitative PCR(RT-qPCR)and Western blotting(Western blot,WB).(3)the effect of GGT5 silencing on the proliferation of MGC803 gastric cancer cell line was detected by CCK-8 and Edu assay.(4)the effect of GGT5 silencing on the invasive ability of MGC803 gastric cancer cell line was detected by cell scratch test.(5)to explore the effect of GGT5 on the marker proteins in the process of epithelial mesenchymal transition(EMT)in gastric cancer cells by Westernblot experiment.Results:(1)A total of 194 metabolic genes differentially expressed in gastric cancer were analyzed by TCGA database and GSEA database.Ten of these genes are the core genes in the PPI map.(2)Prognostic analysis of differentially expressed metabolic genes showed that 23 genes were associated with the prognosis of gastric cancer,and it was concluded that GGT5 was not only related to the prognosis of gastric cancer,but also the core gene in the protein interaction map.(3)by analyzing the clinicopathological factors of gastric cancer,it was found that the expression of GGT5 was positively correlated with T stage,histological grade and pathological stage of gastric cancer.(4)through the analysis of tumor immunity,it was found that the expression of GGT5 could promote the infiltration of tumor-associated immune cells such as macrophages,DC cells and neutrophils and the overexpression of immunosuppressants such as PDCD1,CTLA4,CD96.(5)in terms of tumor metabolism,it was found that the expression of GGT5 played an important role in MAPK,P13KAKT,RAS and other signal pathways in gastric cancer,and was closely related to glutathione,glutamate and deoxynucleotides metabolism in gastric cancer.(6)the mRNA and protein expression levels of MGC803 gastric cancer cell lines silenced by GGT5 were decreased,and the difference was statistically significant.(7)the proliferation and invasive ability of MGC803 gastric cancer cell line silenced by GGT5 were significantly decreased,and the difference was statistically significant.(8)the expression of EMT marker protein in MGC803 gastric cancer cell line silenced by GGT5 was also significantly inhibited.Conclusions:GGT5 is highly expressed in gastric cancer and is closely related to many biological functions such as pathological stage,immune infiltration and tumor metabolism.GGT5 promotes the proliferation and invasion of gastric cancer cells in vitro,which may be achieved by promoting epithelial-mesenchymal transformation(EMT),and then affect the survival and prognosis of patients with gastric cancer. |
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