Abstract: Objective This study aimed to screen for cancer-testis antigens with immune function in differentially expressed genes between gastric cancer tissues and normal tissues, and to explore the effect of such antigens on survival and prognosis of gastric cancer.Methods The TCGA database was used to screen the genes with significant differences in the expression between gastric cancer tumor tissues and normal tissues.At the same time, the cancer-testis antigens that had been confirmed in the literature and induced immune responses were screened in the CTdatabase.The cancer-testis antigens with the function of inducing immune response were screened from the differentially expressed genes, and the survival analysis was carried out in combination with the clinical information of patients, and the prognosis-related cancer-testis antigens were further analyzed by CIBERSORT for immune infiltration.Results A total of 5514 differentially expressed genes were screened out through the TCGA database.There were 94 cancer-testis antigens with the function of inducing immune response in the CTdatabase.Comparing with the differential expressed genes of gastric cancer, a total of 33 differentially expressed cancer-testis antigens with the function of inducing immune response were obtained.Among them, 27 cancer-testis antigens were highly expressed in gastric cancer tumor tissues, including ARMC3, CDCA1, CEP55, CSAG2, CT45A1, CTAG2, CTCFL, CXorf61(KK-LC-1), DDX53, IGF2BP3, MAGEA1, MAGEA10, MAGEA12, MAGEA3, MAGEA4, MAGEA6, MAGEC1, MAGEC2, KIF2C, MPHOSPH1, PLAC1, PRAME, SAGE1, SEMG1, SPAG17, SSX1, TTK, and had been confirmed in the literature to have the ability to induce immune responses.The expressions of BAGE2, CCDC110, SPAG4, SPAG8, IGSF11 and MAGEB2 in tumor tissues were lower than those in normal tissues.Furthermore, the survival analysis found that the high expressions of CEP55, MAGEA10, MAGEA12, MAGEA3, MAGEC1, and PLAC1 was significantly associated with the shorter survival of patients with gastric cancer, and was positively correlated with the infiltration ratio of M1 macrophages with anti-tumor ability in the tumor immune microenvironment.The multivariate analysis by the Cox regression model showed that the expression of CEP55 was significantly associated with shorter survival of patients.Conclusion In this study, the cancer-testis antigens with the function of inducing immune response were screened from the highly expressed genes in gastric cancer tissues, which provided a basis for the search targets of gastric cancer immunotherapy.

Key words: Gastric cancer, Cancer testis antigen, Differently expressed genes, TCGA, Immunotherapy