Overexpression of miR-20a promotes the progression of osteosarcoma by directly targeting QKI2

Osteosarcoma (OS) is the most common type of malignant primary bone neoplasm. Although the application of neoadjuvant chemotherapy has improved the 5-year survival rate of patients suffering from OS, prognosis remains poor. Therefore, it is important to elucidate the molecular mechanisms underlying the occurrence, progression and metastasis of OS. The RNA-binding protein Quaking (QKI) is a member of the STAR family of proteins, and can function as a tumor suppressor gene to suppress the occurrence and progression of a variety of tumors; however, the role of QKI in OS remains to be fully elucidated. In the present study, it was identified that the expression of QKI2 was downregulated in OS using western blot analysis. In addition, subsequent functional investigations, including MTT, Transwell invasion and migration assays, revealed that QKI2 inhibited the proliferation, invasion and migration of an OS cell line in vitro. By implementing a series of experimental techniques in molecular biology, including reverse transcription-quantitative polymerase chain reaction and a double fluorescence reporter assay, it was demonstrated that the expression of miR-20a was high and inhibited the expression of QKI2 in OS. In conclusion, it was revealed that aberrantly upregulated miR-20a inhibited the expression of QKI2 in OS by targeting QKI2 mRNA, subsequently promoting the proliferation, migration and invasion of OS cells.