Objective      To explore the roles of microRNA-206 (miR-206) and connexin 43 (Cx43) in the cell proliferation

migration and invasion of breast cancer.       Methods      With qRT-PCR

the miR-206 expression levels of breast cancer cell lines MDA-MB

-231 and MCF-7 and normal mammary gland cell line MCF-10A were detected. The levels of miR-206 in MDA-MB-231 and MCF-7 cells were up-regulated or down-regulated by lentiviral vector-mediated transfection. Cx43 expression was detected by qRT-PCR and Western blotting. Cell migratory and invasive abilities were measured by Transwell chamber assay.       Results      It was found that there was obviously lower expression of miR-206 in breast cancer cells than in normal cells. MCF-7 cells showed lower miR-206 level but higher Cx43 level than MDA-MB-231 cells. After shRNA-mediated miR-206 up-regulation

MCF-7 cells displayed increase of miR-206 level

decrease of Cx43 mRNA and protein expression

and suppression of cell proliferation

migration and invasion (

P

0.05). After shRNA-mediated miR-206 down-regulation

MDA-MB-231 cells displayed decrease of miR-206 level

increase of Cx43 mRNA and protein expression

and enhancement of cell proliferation

migration and invasion (

P

0.05).       Conclusion      MicroRNA-206 inhibits migration and invasion of breast cancer cells through down-regulation of Cx43 expression possibly

which indicates the tumor-suppressive function of microRNA-206 in breast cancer.