MicroRNA-497acts as a tumor suppressor in gastric cancer and is downregulated by DNA methylation

Gastric cancer (GC) is one of the most common malignant tumors in the world and microRNAs (miRNAs) play an important role in GC. In this study, we found miR-497 played an important role and served as a novel biomarker in GC. Quantitative real-time PCR (qRT-PCR) was used to measure the miR-497 expression in GC cell lines and 86 paired GC samples and we also analyzed its correlation with GC clinicopathological parameters. A series of cellular function experiments were applied to validate the effects of miR-497 on GC. In addition, methylation-specific PCR (MSP) was applied to detect the gene methylation status. Finally, the correlation between miR-497 and the target gene was analyzed by western blotting assay. miR-497 was reduced obviously in GC cells and tissues and significantly associated with the pathologic stage. Low expression of miR-497 significantly inhibited the proliferation, invasion and migration of GC cell lines and accelerated apoptosis. Moreover, we found that the aberrant expression of miR-497 may be ascribed to DNA methylation. microRNA.org and luciferase reporter assay suggested that RAF1 was a direct target of miR-497 in GC. This study suggested that miR-497 could serve as a tumor suppressor and a potential early diagnostic marker of GC by targeting Raf-1 proto-oncogene, serine/threonine kinase (RAF1).