Decreased expression of miR-193b by DNMT1 affects gastric cancer cell proliferation and migration

MicroRNA (miR)-193b has been implicated in numerous types of cancer, however, the mechanism underlying the effects of miR-193b in gastric cancer (GC) have remained to be elucidated. In this study, we aimed to identify the mechanisms by which miR-193b is regulated as well as the functional role of miR-193b in GC. Decreased expression levels of miR-193b was detected in GC samples and cell lines by reverse transcription quantitative polymerase chain reaction, the expression level of miR-193b correlated with lymph node metastasis in patients with GC (P<0.05). 5-Aza-2'-deoxycytidine (5'-Aza) treatment and DNA methyltransferase 1 (DNMT1) knockdown restored the level of miR-193b in GC cells. Functional studies demonstrated that elevated expression of miR-193b by transient transfection was able to inhibit the proliferation and migration of GC cells. Furthermore, myeloid cell leukemia (MCL) 1 was validated as the target of miR-193b by luciferase assay, and overexpression of miR-193b suppressed the expression of MCL1. The results of the present study suggested miR-193b acts as a tumor suppressor in GC cells, and the reduced expression of miR-193b in GC cells may be in part due to epigenetic regulation via DNMT1.