Abstract
MicroRNAs (miRs) are a type of small non-coding RNA that serve crucial roles in the development and progression of breast cancer. However, the exact role and underlying molecular mechanism of miR-375 in mediating the growth and metastasis of breast cancer remains unknown. In the present study, reverse transcription-quantitative polymerase chain reaction and western blot analysis were conducted to examine RNA and protein expression. A luciferase reporter assay was performed to determine the association between miR-375 and paired box 6 (PAX6). The results of the current study indicate that the expression of miR-375 was reduced in breast cancer tissues compared with matched adjacent normal tissues. Transfection with miR-375 mimics led to a significant increase in levels of miR-375 in human breast cancer Michigan Cancer Foundation (MCF)-7 cells (P<0.05). The increase in miR-375 expression caused a significant decrease in the viability, migration and invasion of MCF-7 cells (P<0.05), accompanied by a reduced expression of matrix metalloproteinase (MMP) 2 and MMP9 proteins. Luciferase reporter assay identified PAX6 as a novel target of miR-375 and miR-375 in turn, negatively regulated the protein expression of PAX6 in MCF-7 cells. By contrast, overexpression of PAX6 led to a significant increase in MCF-7 cell viability (P<0.01) but did not affect the migration and invasion of MCF-7 cells, suggesting that the inhibitory effect of miR-375 on MCF-7 cell viability may be occurring, in part, via the direct targeting of PAX6.