Abstract:

Objective To determine the expressions of microRNA-335（miR-335）and Fos related antigen-1（Fra-1）in breast cancer tissues and cells，and to investigate the relationship between them. Methods The breast cancer tissues and corresponding paracancerous tissues from 41 patients were collected（>2 cm and <3 cm away from the lesions）. The expressions of miR-335，Fra-1 mRNA and Fra-1 protein were determined in different tissues，breast cancer cell lines（MDA-231 and MCF-7） and normal breast cell line（MCF-10A）. Breast cancer cell lines（MDA-231 and MCF-7） were transfected with miR-335 containing plasmid（miR-335 mimic） and control plasmid（mimic control），and the effect of miR-335 overexpression on Fra-1 mRNA and Fra-1 protein expressions was analyzed. Pearson correlation analysis was used to evaluate the correlation between miR-335 and Fra-1. Results Compared with the normal breast cell line（MCF-10A），the expression of miR-335 in breast cancer cell lines（MCF-7 and MDA-231） was decreased（P<0.05），and the expressions of Fra-1 mRNA and Fra-1 protein were increased（P<0.05）. Compared with tumor-adjacent tissues，the expression of miR-335 in breast cancer tissues was decreased（P<0.05），and the expressions of Fra-1 mRNA and Fra-1 protein were increased（P<0.05）. The positive expression of Fra-1 in breast cancer tissues was higher than that in adjacent tissues（P<0.05）. Compared with their respective control groups，the expressions of miR-335 in MCF-7 cells and MDA-231 cells transfected with miR-335 mimic were up-regulated（P<0.05），and the expressions of Fra-1 mRNA and Fra-1 protein were down-regulated（P<0.05）. Pearson correlation analysis showed that miR-335 was negatively correlated with Fra-1 mRNA（r=-0.830 4，P<0.05）. Conclusions The expression of miR-335 decreases，and Fra-1 increases in breast cancer tissues and cell lines. Overexpression of miR-335 reduces the expression of Fra-1 in breast cancer cells.

Key words: MicroRNA-335, Fos related antigen-1, Breast cancer