Up-regulated Circulating miR-106a by DNA Methylation Promised a Potential Diagnostic and Prognostic Marker for Gastric Cancer

Previous studies suggested that abnormal miRNA expression was a significant characteristic of malignant tumors. We aimed to explore the role of miR-106a as the potential diagnostic and prognostic biomarker in gastric cancer (GC). Firstly, the expression level of miR-106a was detected by qPCR in 28 pairs of GC cancer tissues and adjacent tissues, 48 pairs of plasma samples before and after operation from GC patients, and 22 plasma samples from healthy controls. It had revealed that the level of miR-106a in tumor tissues (2.700 +/- 2.565) was significantly higher compared to adjacent tissues (1.321 +/- 0.904) (p<0.05). Besides, the expression level of miR-106a in plasma of GC (9.479 +/- 5.595) was significantly up-regulated compared with healthy controls (2.594 +/- 2.329) (p<0.05), while a remarkable decline of miR-106a expression was observed in plasma of GC patients after gastrectomy. Further statistic data showed high miR-106a expression was closely related to the degree of lymphatic metastasis and TNM staging of GC. We also applied ROC curve in order to evaluate miR-106a as a diagnostic marker for GC patients. As a result, the sensitivity and specificity were 60.4%, 68.2% in tissue samples and 72.9%, 63.6% in plasma samples, respectively. At last, we explored the methylation status of miR-106a promoter in 28 paired GC tissues through methylation-specific PCR (MSP), the result showed that the methylation rate was 53.6% in cancer tissues and 85.7% in adjacent tissues. Moreover, the result indicated that promoter hypomethylation of miR-106a is related to its high expression. Our research indicated that miR-106a might serve as a potential prognostic indicator in progressive GC and up-regulated circulating miR-106a by promoter hypomethylation, might be proposed as a candidate diagnostic and prognostic indicator for GC.