Study On The Multiple Roles Of THY1 Gene In Gastric Cancer Based On Bioinformatics Analysis

Background: According to the statistics of malignant tumors in 2018,the incidence rate of gastric cancer(GC)in the world ranks fifth in all malignant tumors,and the mortality rate is third.At present,radical operation of gastric cancer is still the main method to cure gastric cancer.However,most patients with surgery were diagnosed as advanced and had a low 5-year survival rate.Although many cancer genes and anti-cancer genes have been identified to play an important role in the development of gastric cancer,there are still no targeted large-scale clinical applications of drugs.Therefore,it is of great clinical value to explore the molecular mechanism of gastric cancer occurrence and development,find reliable biomarkers and use it as the target of early cancer diagnosis and treatment.THY1(thymocyte differentiation antigen 1)is a kind of cell surface protein anchored by triglyceride to the carboxyl end of glycosylphosphatidylinositol(GPI),which is related to many kinds of cancer.There are few studies on the function and mechanism of THY1 in gastric cancer cells,so it is very important to clarify the role of THY1 in the development and disease process of gastric cancer.Objective: To analyze the expression of THY1 in GC by using database and clinical data,and to evaluate the clinical significance and prognosis of THY1 in gastric cancer;The results of the above prediction were verified by clinical tissue samples;The effect of THY1 on the malignant phenotype of gastric cancer cells was studied by in vitro cell experiments;The possible protein and pathway of THY1 involved in the development and migration of gastric cancer cells were analyzed by data network system;The relationship network of the possible immune related proteins of THY1 was predicted and verified.Methods: The first part: the high expression of THY1 in different tumors was analyzed by database.The difference expression of THY1 between gastric cancer specimens and adjacent tissues was analyzed.The correlation between THY1 and clinical stages and prognosis of gastric cancer patients was analyzed.The expression of THY1 in gastric cancer tissues and adjacent tissues was verified by QRT PCR,and the correlation analysis was made with clinicopathological and prognosis data.The second part: To study the localization of THY1 in the cell.After silencing THY1 with small interfering RNA,CCK-8,plate clone,Transwell and scratch test were used to detect the effect of THY1 on the proliferation,migration and invasion of gastric cancer cells.The effects of interference on autophagy of gastric cancer cells were observed.The third part: the data network system is used to analyze the possible protein and pathway of THY1 involved in the development and migration of gastric cancer cells and the relationship network of THY1 related immune related proteins,and preliminarily verify the correlation between THY1 and immunosuppressive molecules.Results: The first part: TCGA database showed that THY1 was expressed in many kinds of cancer,gepia database and clinical pathological data showed that THY1 expression in gastric cancer tissue was significantly higher than that in adjacent tissues,and its expression was positively correlated with TNM stage in GC patients,and the total survival rate(OS),first progress(FP)and post progress survival rate(PPS)of GC patients with high expression of THY1 were lower.The expression of THY1 in gastric cancer tissues was significantly increased by QRT PCR.The clinicopathological data showed that THY1 was positively correlated with TNM stage and negatively correlated with prognosis.The second part: the human protein map database shows that THY1 is distributed in the nucleus and membrane in PC-3and U-251 mg cell lines.The results showed that the knockdown of THY1 gene inhibited the proliferation,migration and invasion of GC cells;The expression of autophagy related proteins LC3 and p62 in GC cells of Si THY1 also changed.After Si THY1,the expression of p62 protein decreased and LC3 protein increased.The double fluorescence was constructed by mscurry EGFP lc3 b transfection,which showed that the autophage fluorescence level of cancer cells increased after Si THY1.Part three: the interaction network analysis of string shows that some proteins include CD34,Alpl,ITGB3,etc.,which may interact with THY1.Metascape was used to analyze co expressed genes.The results showed that THY1 was mainly involved in the process of phosphorylation of intercellular connection and p53 signaling pathway;The results of GSEA pathway enrichment analysis show that THY1 participates in many classical tumor related signaling pathways,such as EMT signaling pathway,JAK pathway?STAT3 signal path,KRAS signal path,etc.The expression of THY1 was positively correlated with Tregs cells,and the immunomarkers including lymphocyte activation gene-3(Lag3),programmed cell death 1(PDCD1),T-cell immunoglobulin and ITIM domain protein(tigit),cytotoxic T-lymphocyte antigen 4(CTLA4),indoleamine 2,3-dioxase(ido1)were highly correlated.Conclusion: Our results show that the high expression of THY1 is related to the poor prognosis of GC patients.THY1 has potential to be a marker for evaluating the microenvironment of GC patients and the target of immunotherapy.