The Association of EBV and Gastric Cancer

Abstract

The present study aimed to investigate the clinicopathological features of EBV positive and EBV negative gastric cancer patients and the expression levels of proliferative, apoptotic and cell signaling proteins in tissues samples from these patients. The biological role of EBV infection was assessed in gastric cancer. Results: EBV was localized in the nuclei of gastric cancer cells (positive rate 6.86%). The infection rate of EBV in normal gastric mucosal cells, which were adjacent to cancer tissues, was 0. The difference noted was significant (P = 0. 023). The expression levels of caspase-3 (P = 0.0423), FASL (P = 0.00297) and cyclin D1 (P = 0.0345) proteins were significantly different in EBV positive and negative gastric cancer tissues. When the parameters gender, age, Lauren classification, histological grade, early and advanced tumor stage, vascular and nerve invasion, TNM grade and survival status were compared, the maximum tumor diameter, number of lymph node metastasis, caspase-8, Ki67 and P53 protein expression did not reveal significant differences. Bcl-2 protein expression was positive in only one gastric cancer cell sample and negative in the other gastric cancer cell samples as well as in the corresponding normal gastric mucosal epithelial cells. However, significant differences were noted with regard to the positive expression of Bcl-2 in the immune cells of gastric cancer and adjacent tissues (P = 1.17749E-39). The expression levels of Bcl-2 in the immune cells of EBV positive and EBV negative gastric cancer tissues were not significantly different. The expression levels of caspase-8, caspase-3, FASL, Ki67, cyclin D1 and P53 proteins in gastric cancer cells were significantly different compared to those of normal gastric mucosal cells derived from adjacent tissues (P < 0.05). These findings were noted in both EBV positive and/or EBV negative gastric cancer cases (P < 0.05). The survival time of the patients with EBV positive gastric cancer was higher than that of the patients with EBV negative gastric cancer, whereas the differences were not significantly different. The aforementioned results suggested that the EBV virus may directly infect cancerous cells but not normal gastric mucosal cells. With the exception of caspase-3, the expression levels of the proteins FASL and cyclin D1 were closely associated with EBV-positive gastric cancer. EBV did not have a specific effect on the expression of the signaling molecules associated with proliferation and apoptosis of gastric cancer cells. Its effect on gastric cancer cells may be associated with other factors and requires further discussion. No significant differences were noted in the clinicopathological features of EBV positive compared to those of EBV negative gastric cancer patients. However, the prognosis of EBV positive gastric cancer patients was better than that of EBV negative gastric cancer patients. The mechanism of action associated with these processes requires further verification.