Correlation of the Expression of TGF-β and PD-L1 and Cancer-immune Phenotypes in Gastric Cancer and Its Clinical Significance

OBJECTIVE To detect the expression of TGF-β and PD-L1 in gastric cancer, and to explore the relationship between them and cancer-immune phenotypes and their clinical significance. METHODS The paraffin tissue samples and clinicopathologic features of 84 patients who underwent gastrectomy in Lianyungang Clinical Medical College of Nanjing Medical University from 2017 to 2019 were collected. The expression of PD-L1, TGF-β and CD8⁺T cells was detected by immunohistochemistry method. The relationship between the expression of TGF-β, PD-L1 and cancer-immune phenotypes and their clinical significance was analyzed by GraphPad Prism7 and SPSS 21.0 statistical software. RESULTS The positive expression rate of TGF-β and PD-L1 in gastric cancer were 76.2% and 79.7% respectively. The immunophenotypes of immune-inflamed, immune-excluded and immune-desert in gastric cancer were 33.3%, 51.2% and 15.5%, respectively. There was significant difference in the expression of TGF-β among the three immunophenotypes in gastric cancer(P<0.05). Among them, there was a significant positive correlation between immune-excluded and the expression level of TGF-β in gastric cancer(P<0.05). However, there was no significant difference in the expression of PD-L1 among the three immunophenotypes in gastric cancer. The expression of TGF-β was correlated with that of PD-L1 in gastric cancer positively(P<0.05). The expression of TGF-β in gastric cancer was related to lymph node metastasis(P<0.05) and TNM stage(P<0.05) significantly. The expression of PD-L1 in gastric cancer was related to the degree of tumor invasion(P<0.05), lymph node metastasis(P<0.05) and TNM stage(P<0.05) significantly. The immune-excluded was related to the tumor diameter(P<0.05) significantly. The expression of immune-inflamed was related to the diameter of tumor(P<0.05). CONCLUSION Both TGF-β and PD-L1 are expressed in gastric cancer, and the expression of TGF-β is positively correlated with the expression of PD-L1 in gastric cancer. There is a significant positive correlation between immune-excluded and TGF-β expression in gastric cancer, and most of the patients with high expression of TGF-β were immune-excluded immunophenotypes. There is no significant correlation between PD-L1 expression and tumor immunophenotypes in gastric cancer. The expression of TGF-β, PD-L1 and tumor immunophenotypes in gastric cancer are closely related to some clinicopathological features such as the degree of tumor invasion, lymph node metastasis TNM stage and the tumor diameter.