MiR-378 promotes the cell proliferation of osteosarcoma through down-regulating the expression of Kruppel-like factor 9.

MicroRNAs (miRNAs) are small non-coding RNAs that play important roles in a variety of biological processes. Dysregulation of miRNAs is tightly associated with the malignancy of cancers. Aberrant expression of miR-378 has been observed in human cancers; however, the function of miR-378 in osteosarcoma (OS) remains largely unknown. Here, we showed that miR-378 was highly expressed in human OS tissues and cell lines. Overexpression of miR-378 significantly promoted the cell proliferation of OS cells. Molecular studies identified Kruppel-like factor-9 (KLF9) as a functional downstream target of miR-378. MiR-378 directly bound to the mRNA 3'-UTR region of KLF9 and suppressed the expression of KLF9. Highly expressed KLF9 reversed the promoting effect of miR-378 on the proliferation of OS cells. The expression level of miR-378 was negatively correlated with that of KLF9 in OS tissues. Collectively, our results demonstrated the molecular interaction between miR-378 and KLF9, indicating the therapeutic potential of miR-378 for OS.