Tumor-suppressive effect of miR-148a on salivary adenoid cystic carcinoma via down-regulation of MTA2

The aim of this study was to investigate the effect on miR-148a of salivary adenoid cystic carcinoma cells (SACC) and to clarify the mechanism. Expression of miR-148a and MTA2 was analyzed by real-time PCR in SACC cancer tissues and SACC cell lines. Available software algorithms, luciferase reporter assay system, agarose gel electrophoresis, and Western blotting were used to explore the potential target genes of miR-148a in SACC. Realtime PCR showed that expression of miR-148a was significantly decreased in SACC cancer tissues compared with normal tissues. Northern blotting results revealed significant down-regulation in SACC cancer tissues compared with normal tissues. The SACC cell line ACC-M transfected with miR-148a mimics could increase the expression level of miR-148a effectively. Compared with the NC group, cell proliferation, invasion rate, and cell migration ability of the mimics group declined. MiRanda, Mirwalk, and Targetscan predicted that human MTA2 was a target gene of miR-148a. Luciferase reporter assay showed that there was a site of miR-148a in the MTA2 mRNA 3'-UTR region. Western blotting showed that overexpression of miR-148a inhibited expression of MTA2. Up-regulation of MTA2 expression transfected with miR-148a mimics promoted cell proliferation, migration, and invasion compared with the negative and miR-148a mimic groups. Expression of miR-148a was down-regulated in SACC tissues. Additionally, miR-148a negatively regulated cell proliferation, migration, and invasion by down-regulation of MTA2, which is a target gene of miR-148a. Therefore, miR-148a suppresses expression of the MTA2 gene and plays a role of tumor suppressor gene in SACC.