Blocking miR-27a-3p sensitises Taxol resistant osteosarcoma cells through targeting Fbxw7

Osteosarcoma (OS) is a human malignancy, which primarily affects the long bones and occurs in children and adolescent. Although advanced clinical approaches and the addition of neoadjuvant chemotherapy improved 5-year survival of OS patients, a large fraction of them developed chemoresistance. Thus, due to the high morbidity and mortality of OS, it is urgent to investigate effectively molecular targets against chemoresistant osteosarcoma. In this study, we aimed to evaluate the functions of miR-27a-3p in the Taxol sensitivity of osteosarcoma. From fifty-paired OS tumour tissues and adjacent normal bone tissues, we detected significantly upregulated miR-27a-3p expressions in osteosarcoma. In addition, expression of miR-27a-3p was remarkedly elevated in OS cancer cell lines compared with normal osteoblast cells, hFOB1.19. Blocking miR-27a-3p effectively suppressed OS cell growth and sensitised OS cells to Taxol. miRNA target prediction indicated Fbxw7 was a potential target of miR-27a-3p. We demonstrated Fbxw7 functioned as a tumour suppressor in osteosarcoma. Overexpression of miR-27a-3p significantly suppressed Fbxw7 protein expression in OS cells. The direct binding between miR-27a-3p and Fbxw7 3'UTR was validated by luciferase assay. Particularly, results from rescue experiments by inhibiting Fbxw7 expressions in miR-23a-3p-blocked OS cells demonstrated the miR-27a-3p-mediated Taxol resistance was through direct targeting Fbxw7. In summary, our findings report a new molecular mechanism for the miR-27a-3p-mediated Taxol resistance via targeting tumour suppressor, Fbxw7 in osteosarcoma. This study potentiates a miRNA-based therapeutic approach against Taxol resistant osteosarcoma.