MicroRNA-32 promotes cell proliferation, migration and suppresses apoptosis in breast cancer cells by targeting FBXW7.
BACKGROUND
MicroRNAs are a class of small non-coding RNAs that are involved in many important physiological and pathological processes by regulating gene expression negatively. The purpose of this study was to investigate the effect of miR-32 on cell proliferation, migration and apoptosis and to determine the functional connection between miR-32 and FBXW7 in breast cancer.


METHODS
In this study, quantitative RT-PCR was used to evaluate the expression levels of miR-32 in 27 breast cancer tissues, adjacent normal breast tissues and human breast cancer cell lines. The biological functions of miR-32 in MCF-7 breast cancer cells were determined by cell proliferation, apoptosis assays and wound-healing assays. In addition, the regulation of FBXW7 by miR-32 was assessed by qRT-PCR, Western blot and luciferase reporter assays.


RESULTS
MiR-32 was frequently overexpressed in breast cancer tissue samples and cell lines as was demonstrated by qRT-PCR. Moreover, the up-regulation of miR-32 suppressed apoptosis and promoted proliferation and migration, whereas down-regulation of miR-32 showed an opposite effect. Dual-luciferase reporter assays showed that miR-32 binds to the 3'-untranslated region of FBXW7, suggesting that FBXW7 is a direct target of miR-32. Western blot analysis showed that over-expression of miR-32 reduced FBXW7 protein level. Furthermore, an inverse correlation was found between the expressions of miR-32 and FBXW7 mRNA levels in breast cancer tissues. Knockdown of FBXW7 promoted proliferation and motility and suppressed apoptosis in MCF-7 cells.


CONCLUSIONS
Taken together, the present study suggests that miR-32 promotes proliferation and motility and suppresses apoptosis of breast cancer cells through targeting FBXW7.
Institute of Genetic Engineering, Southern Medical University, Guangzhou, 510515 People's Republic of China.|Department of Clinical Laboratory, No.421 Hospital of PLA, Guangzhou, People's Republic of China.
Wei
W
Xia
Institute of Genetic Engineering, Southern Medical University, Guangzhou, 510515 People's Republic of China.
JueYu
J
Zhou
Department of Clinical Laboratory, No.421 Hospital of PLA, Guangzhou, People's Republic of China.
HaiBo
H
Luo
Department of Clinical Laboratory, No.421 Hospital of PLA, Guangzhou, People's Republic of China.
YunZhou
Y
Liu
Institute of Genetic Engineering, Southern Medical University, Guangzhou, 510515 People's Republic of China.
CanCan
C
Peng
Institute of Genetic Engineering, Southern Medical University, Guangzhou, 510515 People's Republic of China.
WenLing
W
Zheng
Institute of Genetic Engineering, Southern Medical University, Guangzhou, 510515 People's Republic of China.
WenLi
W
Ma
Apoptosis; Breast cancer; FBXW7; MiR-32; Proliferation