Int J Biol Sci 2011; 7(6):805-814. doi:10.7150/ijbs.7.805 This issue
Department of Immunology, Shanghai Medical College, Key Laboratory of Molecular Medicine of Ministry of Education, Fudan University, Shanghai, China.
* Shudao Xiong and Yijie Zheng contributed equally to this work and should be considered as co-first authors.
MicroRNAs(miRNAs) are emerging as important regulators in tumorigenesis. Increasing evidences have indicated microRNA-7(miR-7) to be a potential tumor suppressor in several human cancers. However, only a limited number of target genes have been identified so far and its biological function in Non-Small Cell Lung Cancer (NSCLC) remains to be further elucidated. In the present study, we observed a reduction of miR-7 level in NSCLC cell lines. Overexpression of miR-7 not only suppressed NSCLC A549 cells proliferation, induced cell apoptosis and inhibited cell migration in vitro, but also reduced tumorigenicity in vivo. Bioinformatics predictions revealed a potential binding site of miR-7 on 3'UTR of BCL-2 and it was further confirmed by luciferase assay. Moreover, subsequent experiments showed that BCL-2 was downregulated by miR-7 at both transcriptional and translational levels. These results suggest that miR-7 regulates the expression of BCL-2 through direct 3'UTR interactions. Therefore, we postulate BCL-2 to be a novel target possibly involved in miR-7-mediated growth suppression and apoptosis of A549 cells. These findings may provide a basic rationale for the use of miR-7 in the treatment of NSCLC.
Keywords: miR-7, BCL-2, non-small cell lung cancer, A549 cells, apoptosis.