miR-21 induces cell cycle at S phase and modulates cell proliferation by down-regulating hMSH2 in lung cancer.
OBJECTIVE
MicroRNAs regulate critical genes associated with lung cancer. Human mutS homolog 2 (hMSH2), one of the core mismatch repair genes, is affected in lung cancer development. The aim of this study is to investigate the role of miR-21 in hMSH2 gene expression and the effect of miR-21 on cell proliferation and cell cycle in lung cancer.


METHODS
The targets of miR-21 were predicted by a bioinformatics tool, and hMSH2 was validated as a direct target of miR-21 by luciferase activity assay. MiRNA mimics or inhibitors were used to stimulate or attenuate the effect of endogenous miR-21 on hMSH2 expression. MiR-21 and hMSH2 expressions were assessed with real-time RT-PCR and Western blotting. Cell cycle was determined by flow cytometry, and cell growth was analyzed by MTT assay and real-time cell analysis system.


RESULTS
MiR-21 expression was inversely correlated with hMSH2 expression in human lung cancer cell lines. Further validation showed hMSH2 was directly regulated by miR-21. The up-regulation of miR-21 significantly promoted cell proliferation and revealed a higher proportion of cells at S phase. However, knockdown of miR-21 expression resulted in cell cycle arrest at G2/M phase and inhibited cell proliferation.


CONCLUSIONS
These data suggest miR-21 is a key regulator of hMSH2 and modulates cell cycle and proliferation by targeting hMSH2 in human lung cancer.
Institute of Biochemistry and Molecular Biology, School of Medicine, Ningbo University, 818 Fenghua Road, Ningbo 315211, China.
Zhiwei
Z
Zhong
Zhuo
Z
Dong
Lihua
L
Yang
Zhaohui
Z
Gong
D048708:Cell Growth Processes / Q000235:genetics; D045744:Cell Line, Tumor; D015536:Down-Regulation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics* / Q000473:pathology; D035683:MicroRNAs / Q000235:genetics*; D051718:MutS Homolog 2 Protein / Q000096:biosynthesis / Q000235:genetics*; D016196:S Phase / Q000235:genetics*; D015854:Up-Regulation
C524940:MIRN21 microRNA, human; D035683:MicroRNAs; C497172:MSH2 protein, human; D051718:MutS Homolog 2 Protein