Reduction of miR-21 induces SK-N-SH cell apoptosis and inhibits proliferation via PTEN/PDCD4.

MicroRNA (miR/miRNA)-21 is a well-known oncogenic miRNA that is overexpressed in various types of tumors. The tumor-suppressor genes programmed cell death 4 (PDCD4) and phosphatase tensin homologue (PTEN), are targets of miR-21, and are underexpressed in several types of cancer. However, the expression of miR-21 and its target genes in neuroblastoma (NB) remains unclear. In the present study, a miR-21 inhibitor oligonucleotide was transfected into the SK-N-SH cell line, and the expression of miR-21, PTEN and PDCD4 was detected through quantitative polymerase chain reaction analysis. Western blotting was used to examine levels of PTEN, PDCD4 and caspase-3 proteins. The expression of PTEN and PDCD4 in the SK-N-SH cell line transfected with the miR-21 inhibitor was significantly increased compared with untransfected SK-N-SH and negative control-transfected cells. Cell proliferation was inhibited and the apoptotic ratio was significantly increased in miR-21 inhibitor-transfected cells compared with untransfected SK-N-SH and negative control-transfected cells. Western blot analysis revealed a significant increase in caspase-3 expression compared with untransfected SK-N-SH and negative control-transfected cells. The results of the present study indicate that miR-21 may serve an oncogenic role in the cellular processes underlying NB development and thus may be a novel therapeutic target for the treatment of patients with NB.