Decreased miR-503 expression in gastric cancer is inversely correlated with serum carcinoembryonic antigen and acts as a potential prognostic and diagnostic biomarker

BACKGROUND: Altered expression of miR-503 has been linked to human carcinogenesis. In this present study, we aimed to detect the potential for miR-503 as a novel biomarker for gastric cancer (GC) patients. MATERIALS AND METHODS: The relative mRNA level of miR-503 in serum and tissue of 68 GC patients and serum of 32 healthy volunteers was determined by real-time reverse transcription quantitative polymerase chain reaction. RESULTS: The miR-503 level was significantly lower in the tissue and serum of GC than their counterparts (all P<0.01). Downregulation of miR-503 was found to be corrected with more aggressive tumor. Patients in the high-miR-503 group showed significantly better overall survival compared to the low-miR-503 group (P=0.021). The serum miR-503 level in GC was inversely correlated with carcinoembryonic antigen (CEA) (r=−0.624, P<0.001). Furthermore, the area under the receiver operating characteristic curve for miR-503 discriminating GC patients from healthy individuals was 0.889 (P=0.006), with a sensitivity of 96.8% and a specificity of 79.4%, higher than that of CEA (area under the receiver operating characteristic curve =0.681, P=0.048). CONCLUSION: The present study suggests that the expression level of miR-503 may serve as prognostic and diagnostic biomarker for GC.