miR-16 inhibits cell proliferation by targeting IGF1R and the Raf1–MEK1/2–ERK1/2 pathway in osteosarcoma

• miR-16 is downregulated in OS cells and tumors.
• miR-16 inhibits OS cell proliferation in vitro and in vivo.
• IGF1R is a direct target of miR-16 in OS cells.
• miR-16 suppresses the Raf1–MEK1/2–ERK1/2 pathway in OS cells.
• IGF1R is upregulated in OS tissues and inversely correlated with miR-16 levels.

Several miRNAs have been implicated in the development and progression of osteosarcoma (OS). In this study, we found that miR-16 is downregulated in OS cell lines and tissues. Overexpression of miR-16 suppresses OS cell proliferation and tumor growth in nude mice. Furthermore, we confirmed that IGF1R is a direct target of miR-16. Mechanistic investigation revealed that miR-16 overexpression inhibits the Raf1–MEK1/2–ERK1/2 pathway. In clinical specimens, IGF1R levels inversely correlate with miR-16 expression. Our results provide significant clues regarding the role of miR-16 as a tumor suppressor by targeting IGF1R in OS.