miR-142 suppresses proliferation and induces apoptosis of osteosarcoma cells by upregulating Rb.

It has been reported that microRNA-142 (miR-142) is a tumor suppressor gene. The present study primarily investigated whether the overexpression of miR-142 was able to inhibit the proliferation, apoptosis and expression of apoptosis-associated proteins in osteosarcoma (OS) cells. Different concentrations of miR-142 were transfected into the OS MG-63 cell line using Lipofectamine 2000. The cell lines were divided into three groups: Normal group (non-transfected group), miR-142 transfected group, and negative group, which were transfected with random miR-142 fragment. The proliferation of cells was detected by MTT assay. The expression of miR-142 was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). DAPI staining was performed to investigate the influence of miR-142 on the morphology of MG-63c ells. The apoptotic cell percentages were determined by flow cytometry with Annexin V-fluorescein isothiocyanate/propidium iodide double staining. Expression of tumor suppressors, phosphatase and tensin homolog (PTEN) and Retinoblastoma-associated protein (Rb), and apoptosis-associated proteins were evaluated by western blotting. RT-qPCR indicated a higher expression of miR-142 in the transfected group (miR-142 was transfected into the MG-63 cell line) compared with that in the normal (non-transfected group) and negative control groups. The proliferation of miR-142 transfected cells was significantly lower compared with that in the normal and negative groups. Furthermore, an increased apoptosis rate accompanied by a statistically significant upregulation of PTEN, Rb phosphorylation, cleaved caspase-3 and cytochrome