Thiostrepton and miR-216b synergistically promote osteosarcoma cell cytotoxicity and apoptosis by targeting FoxM1.

Osteosarcoma is a common primary bone cancer that there are currently no effective treatment strategies for. Forkhead box M1 (FoxM1) is key in the development of osteosarcoma, and microRNA (miR)-216b serves an antitumor role by targeting FoxM1. Moreover, thiostrepton (TST), a natural thiazole antibiotic, induces antitumor effects and specifically targets FoxM1. Therefore, the present study investigated whether thiostrepton and miR-216b synergistically inhibited osteosarcoma cells by targeting FoxM1. The MTT assay, reverse transcription-quantitative PCR, a dual-luciferase reporter assay and flow cytometry were performed. Compared with the human osteoblast cell line hFOB1.19, miR-216b expression was significantly downregulated in the osteosarcoma cell lines U2OS, MG63 and Saos-2. By contrast, FoxM1 expression was significantly upregulated in osteosarcoma cell lines compared with the hFOB1.19 cell line. The results indicated that miR-216b targeted the 3'-untranslated region of FoxM1. Moreover, the results suggested that miR-216b cooperated with TST to decrease cell cytotoxicity and increase cell apoptosis. In addition, miR-216b cooperated with TST to increase Bax expression and decrease Bcl-2 expression. In conclusion, the combination of TST and miR-216b synergistically promoted osteosarcoma cell cytotoxicity and apoptosis by targeting FoxM1. Therefore, the present study suggested that the combination of TST and miR-216b may serve as a promising therapeutic strategy for osteosarcoma.