Upregulation of PD-L1 and APE1 is associated with tumorigenesis and poor prognosis of gastric cancer

Yi Qing,1,* Qing Li,1,* Tao Ren,1 Wei Xia,1 Yu Peng,1 Gao-Lei Liu,2 Hao Luo,1 Yu-Xin Yang,1 Xiao-Yan Dai,1 Shu-Feng Zhou,3 Dong Wang1 1Cancer Center, 2Urological Surgery, Daping Hospital and Research Institute of Surgery, Third Military Medical University, Chongqing, People’s Republic of China; 3Department of pharmaceutical Sciences, College of Pharmacy, University of South Florida, Tampa, FL, USA *These authors contributed equally to this work Introduction: Gastric cancer is a fatal malignancy with a rising incidence rate. Effective methods for early diagnosis, monitoring metastasis, and prognosis are currently unavailable for gastric cancer. In this study, we examined the association of programmed death ligand-1 (PD-L1) and apurinic/apyrimidinic endonuclease 1 (APE1) expression with the prognosis of gastric cancer. Methods: The expressions of PD-L1 and APE1 were detected by immunohistochemistry in 107 cases of human gastric carcinoma. The correlation of PD-L1 and APE1 expression with the clinicopathologic features of gastric carcinoma was analyzed by SPSS version 19.0. Results: The positive expression rates of PD-L1 and APE1 in gastric cancer tissues were 50.5% (54/107) and 86.9% (93/107), respectively. PD-L1 and APE1 positive expressions were significantly associated with depth of invasion, lymph node metastasis, pathological type, overall survival, and higher T stage. Furthermore, the expression of PD-L1 in highly differentiated gastric cancers was higher than that in poorly differentiated cancers (P=0.008). Moreover, the expression of APE1 and PD-L1 in gastric cancers was positively correlated (r=0.336, P<0.01). Multivariate analysis showed that the depth of invasion was a significant prognostic factor (risk ratio 19.91; P=0.000), but there was no significant relationship with PD-L1, APE1, prognosis, and other characteristics. Conclusion: The deregulation of PD-L1 and APE1 might contribute to the development and the poor prognosis of gastric cancer. Our findings suggest that high expression of PD-L1 and APE1 is a risk factor of gastric cancer and a new biomarker to predict the prognosis of gastric cancer. Furthermore, our findings suggest that targeting the PD-L1 and APE1 signaling pathways may be a new strategy for cancer immune therapy and targeted therapy for gastric cancer, especially in patients with deep invasion and lymph node metastasis. Keywords: gastric carcinoma, immunohistochemistry, prognostic, potential target