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miR-21 down-regulation promotes apoptosis and inhibits invasion and migration abilities of OVCAR3 cells.

PURPOSE
To investigate the influence of miR-21 down-regulation on cell proliferation, apoptosis, invasion and migration of ovarian papillary adenocarcinoma cell lines (OVCAR3).


METHODS
Short-hairpin RNA (shRNA), specifically targeting miR-21, was constructed and transfected into OVCAR3 cells using the pSIREN-RetroQ linear vector (pSIREN-miR-21). The expression of miR-21 was detected with stem-loop real-time RT-PCR in OVCAR3 cells. Cell proliferation and apoptosis were monitored using the MTT assay and flow cytometry, respectively. Cell migration and invasion were assessed using the transwell migration and scratch-wound assay, respectively. Western-bloting was used for PDCD4 protein expression.


RESULTS
pSIREN-miR-21 suppressed miR-21 expression in OVCAR3 cells. miR-21 expression levels in pSIREN-miR-21 cells was 0.3 ± 0.1, which was significantly lower when compared with pSIREN-miR-21-Neg and control groups (P < 0.01). Cell inhibition rate in the pSIREN-miR-21 group was higher than the control group (29.4% vs 9.0%, P < 0.01), as was the percentage of apoptotic and necrotic cells. By transwell migration assay, the number of cells migrating in the pSIREN-miR-21 group was significantly lower than in the control group. In addition, fewer cells were observed in the wounded area of the pSIREN-miR-21 group following the scratch-wound assay. PDCD4 expression was increased in OVCAR-3 cells transfected by pSIREN-miR-21 compared with vector-control transfected cells. Moreover, the optical density of the transfected cells was significantly lower than the two control groups.


CONCLUSION
Down-regulation of miR-21 dramatically increased apoptotic cell death and decreased cell proliferation, invasion and migration in OVCAR3 cells. MiR-21 may play an important role in the biological behaviors of epithelial ovarian carcinoma cells through negative control of the expression of PDCD4.