Reduced expression of circulating microRNA-218 in gastric cancer and correlation with tumor invasion and prognosis.

AIM: To investigate the expression of microRNA-218 (miR-218) in serum from gastric cancer patients and its relationship with clinicopathological characteristics. METHODS: A total of 68 patients with pathologically diagnosed gastric cancer and 56 healthy individuals were recruited to this study. The expression of miR-218 was detected in the serum of gastric cancer patients and healthy individuals by quantitative real-time polymerase chain reaction. The clinical data were collected and analyzed by statistical software. RESULTS: miR-218 was reduced significantly in the serum of gastric cancer patients compared to healthy individuals (1.15 ± 0.08 vs 0.37 ± 0.023; P = 0.026). In the gastric cancer group, serum expression of miR-218 was lower in patients with metastasis and poorly differentiated cancer compared with non-metastatic and well-differentiated cancer (0.19 ± 0.011 vs 0.45 ± 0.021, P = 0.031 and 0.21 ± 0.019 vs 0.49 ± 0.021, P = 0.025). Serum miR-218 was found to be significantly associated with gastric cancer metastasis (P = 0.003), tumor T stage (P = 0.018) and tumor grade (P = 0.012). Low serum expression of miR-218 was related to an increase in the stage of gastric cancer. The expression level of miR-218 in the serum was correlated with the 3-year survival. Ninety-seven percent of patients with a high level of miR-218 expression survived for 3 years, while only 54% of those with low miR-218 expression survived. CONCLUSION: miR-218 is deregulated in gastric cancer patients and is strongly correlated with tumor stage, grade and metastasis. Serum expression of miR-218 may be a prognostic marker.