miR-23a suppresses proliferation of osteosarcoma cells by targeting SATB1

Accumulating evidence has shown that microRNAs are involved in multiple processes in cancer development and progression. Recent studies have shown that miR-23a functions as an oncogene in various human cancer types, but its role in osteosarcoma remains poorly understood. Here, we demonstrated that miR-23a is frequently downregulated in osteosarcoma specimens and cell lines compared with adjacent noncancerous tissues and cell line. Bioinformatics analysis further revealed SATB1 as a potential target of miR-23a. Data from luciferase reporter assays showed that miR-23a directly binds to the 3'UTR of SATB1 messenger RNA (mRNA). Furthermore, we found that expression patterns of miR-23a were inversely correlated with those of SATB1 in osteosarcoma tissues and cell lines, and overexpression of miR-23a suppressed SATB1 expression at both transcriptional and translational levels in osteosarcoma cell lines. In functional assays, miR-23a inhibited osteosarcoma cell proliferation, which could be reversed by overexpression of SATB1. Furthermore, knockdown of SATB1 reduced osteosarcoma cell proliferation, which resembled the inhibitory effects of miR-23a overexpression. Taken together, our data provide compelling evidence that miR-23a functions as a tumor suppressor in osteosarcoma, and its inhibitory effect on tumor are mediated chiefly through downregulation of SATB1.