MiR-320a effectively suppresses lung adenocarcinoma cell proliferation and metastasis by regulating STAT3 signals

MicroRNAs play important roles in tumorigenesis of various types of cancers. MiR-320a can inhibits cell proliferation of some cancers, but the biologic roles of miR-320a in lung cancer need to be further studied. Here, we investigated the roles of miR-320a in suppressing the proliferation of lung adenocarcinoma cells. MiR-320a treatment was found to effectively suppress LTEP-a-2 and A549 cell proliferation, and induce more apoptotic cells with irradiation treatment compared with control treatment. Our results also showed that miR-320a, as a novel miRNA, directly regulated signal transducer and activator of transcription 3 (STAT3) and its signals, such as Bcl(-)2, Bax, and Caspase 3. The siRNA-inhibited STAT3 levels further proved its roles in regulating STAT3 signals. Moreover, miR-320a treatment effectively suppressed cancer cell growth in mice xenografts compared with controls, and significantly inhibited cell migration in vitro and in vivo. Our findings collectively demonstrated that miR-320a, by directly regulating STAT3 signals, not only suppressed cell proliferation and metastasis, but also enhanced irradiation-induced apoptosis of adenocarcinomia cells.