MIR-27a regulates the TGF- signaling pathway by targeting SMAD2 and SMAD4 in lung cancer

The transforming growth factor- (TGF-) signaling pathway is associated with carcinogenesis and various biological processes. SMAD2 and SMAD4, which are putative tumor suppressors, have an important role in TGF- signaling. The aberrant expression of these genes is implicated in some cancers. However, the mechanisms of SMAD2 and SMAD4 dysregulation are poorly understood. In this study, we observed that miR-27a was upregulated in lung cancer cell lines and patients. In addition, SMAD2 and SMAD4 genes were identified as targets of miR-27a by several target prediction databases and experimental validation. Functional studies revealed that miR-27a overexpression decreased SMAD2 and SMAD4 mRNA and protein levels. Furthermore, miR-27a contributed to cell proliferation and invasion by inhibiting TGF--induced cell cycle arrest. These results suggest that miR-27a may function as an oncogene by regulating SMAD2 and SMAD4 in lung cancer. Thus, miR-27a may be a potential target for cancer therapy.