Abstract
The present study aimed to investigate the role of microRNA (miRNA)-21 in the growth of osteosarcoma. A total of 46 patients with osteosarcoma and 20 healthy controls were included in the study. The expression of miRNA-21 was detected by reverse transcription-quantitative polymerase chain reaction in tumor tissues and adjacent healthy tissues from patients with osteosarcoma, as well as the serum of patients with osteosarcoma and the healthy controls was. Receiver operating characteristic curve analysis was performed to evaluate the diagnostic values of serum miRNA-21 for osteosarcoma at different T stages. Survival curves plotted using the Kaplan-Meier method were used to evaluate the prognostic value. miRNA-21 knockdown osteosarcoma cell lines were established and their effects on cell proliferation were explored using a Cell Counting Kit-8 assay. The effect of miRNA-21 knockdown on the protein expression of phosphatase and tensin homolog (PTEN) and transforming growth factor (TGF)-β1 was detected by western blot analysis. The expression levels of miRNA-21 in tumor tissues were significantly higher compared with the adjacent healthy tissues in the majority of patients with osteosarcoma. The serum miRNA-21 increased as the T-stage of osteosarcoma increased. Serum miRNA-21 may be used to effectively diagnose osteosarcoma and predict the prognosis of the disease. miRNA-21 knockdown inhibited the proliferation of osteosarcoma and promoted the expression of PTEN and TGF-β1 proteins in the osteosarcoma cells. However, TGF-β1 inhibitor treatment reduced the inhibitory effects of miRNA-21 knockdown on osteosarcoma cell proliferation. In conclusion, miRNA-21 inhibition may inhibit osteosarcoma cell proliferation by targeting PTEN and regulating the TGF-β1 signaling pathway.