MicroRNAs (miRNAs) are small conserved RNAs regulating specific target genes in posttranscriptional levels. They have been involved in multiple processes of tumor progression, including cell proliferation. miR-214-5p (also miR-214*) is a newly identified miRNA, and its functions are largely unknown. In this study, we explore the role of miR-214-5p in the proliferation and invasion of human osteosarcoma (OS) cells. The results showed that miR-214-5p was sharply reduced in OS tissues and cell lines, compared with normal tissues and cell lines. In addition, the miR-214-5p mimic greatly increased the miR-214-5p level and significantly decreased the proliferation and invasion of HOS and G293 OS cells. In contrast, the miR-214-5p inhibitor had a completely opposite effect on the miR-214-5p level, cell proliferation, and cell invasion. Moreover, bioinformatics and luciferase reporter gene assays confirmed that miR-1908 targeted the mRNA 3'-UTR region of ROCK1, a characterized tumor promoter in OS. In conclusion, miR-214-5p was identified as a new tumor suppressor, which directly targeted ROCK1 and suppressed proliferation of human OS cells.
Studies have shown that miR-145-3p functions as a tumor suppressor and is associated with tumor growth and metastasis. This study intends to uncover the mechanism of a tumor suppressor of miR-145-3p. The expressions of miR-194 in osteosarcoma cell lines and tissues were monitored by real-time PCR. The proliferation ability was examined by MTT assay. The apoptosis and autophagy of cells were monitored by flow cytometry and microcopy, respectively. The regulation of miR-145-3p on HDAC4 was determined by luciferase assays and western blot assay. The results showed that miR-145-3p was significantly reduced in the osteosarcoma compared with the normal bone tissue. Overexpression of miR-145-3p significantly attenuated the proliferation and induced the apoptosis and autophagy of osteosarcoma cells. Furthermore, we demonstrated that miR-145-3p has inhibited the malignant behavior of osteosarcoma by down-regulating HDAC4 expression. These findings suggested that miR-145-3p may act as a tumor suppressor in osteosarcoma. MiR-145-3p/HDAC4 may be a novel therapeutic target in treatment of osteosarcoma.
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