Serum Interleukin-33 Levels in Patients with Gastric Cancer

Background Interleukin-33 (IL-33) is a novel member of the IL-1 family of cytokines, and it is closely related to IL-18, one of the best characterized members of the IL-1 family. It’s been demonstrated that elevated levels of IL-18 are involved in a wide variety of tumors, especially in gastric cancer. Aims The purpose of this study was to determine the correlations between serum IL-33 levels and the clinicopathologic features in gastric cancer patients. Methods Serum samples were collected from 68 patients with gastric cancer and 57 controls. Serum IL-33 levels were measured by ELISA. Classical tumor markers of CEA and CA19-9 levels were routinely detected by chemiluminescence immunoassay. Western blot analysis was used to detect IL-33 expression in gastric cancer tissue samples and cell lines. The relationship between serum levels of IL-33 and clinical characteristics in patients was analyzed. Results IL-33 levels in the serum of gastric cancer patients were significantly elevated in comparison with that of healthy volunteers. Furthermore, higher serum levels of IL-33 in gastric cancer patients were found to correlate with several poor prognostic factors like depth of invasion, distant metastasis and advanced stage (stage III/IV). On the other hand, serum IL-33 levels did not correlate with CEA and CA19-9. The expression of IL-33 protein was upregulated in carcinoma tissues in comparison with matched normal tissues, and no statistically significant difference was found between the four gastric cancer cell lines and human gastric epithelial cell line GES-1. Conclusions Serum IL-33 may be a useful biomarker for predicting the prognosis of gastric cancer.