MiR-1 Suppresses Proliferation of Osteosarcoma Cells by Up-regulating p21 via PAX3.

miRNA-1(miR-1) is down-regulated in various cancer cells including osteosarcoma cells. This study was conducted to analyze the function of miR-1 in osteosarcoma cells. miR-1 expression in osteosarcoma cells was evaluated by qRT-PCR. Cell proliferation was evaluated after transfecting miR-1 by WST8 assay and FACS analysis, both in vitro and in vivo. Overexpression of miR-1 suppressed cell proliferation and induced cell-cycle arrest in the G0-G1 phase by increasing p21 levels via a p53-independent pathway. Overexpression of miR-1 down-regulated PAX3, a potential p21-regulating gene. Moreover, knockdown of PAX3 suppressed cell proliferation by increasing p21 levels, and induced arrest at the G0/G1 phase. Administration of miR-1 showed an in vivo antitumor effect. Overexpression of miR-1 suppressed cell proliferation and induced arrest in the G0/G1 phase by increasing p21 levels via a p53-independent pathway through PAX3 suppression. These results indicate that miR-1 could be a therapeutic target for osteosarcoma.

Fujii R ，Osaka E ，Sato K ，Tokuhashi Y ... -  《-》

Loss of MicroRNA-489-3p promotes osteosarcoma metastasis by activating PAX3-MET pathway.

Osteosarcoma (OS) remains one deadly disease for many affected patients. MicroRNAs (miRNAs) are thought to have an important role in tumor metastasis by regulating diverse cellular pathways. Here, we describe the function and regulation network of miR-489-3p in osteosarcoma (OS) metastasis. MiR-489-3p expression was downregulated in OS cells especially in high metastatic potential cells and was also significantly decreased in metastatic lesions compared with their corresponding primary tumor samples. Both gain- and loss-of-function studies confirmed that miR-489-3p significantly suppressed OS cell invasion and metastasis both in vitro and in vivo. Mechanistically, paired box gene 3 (PAX3) was identified as a functional target of miR-489-3p in OS cells. MiR-489-3p inhibited OS metastasis by negatively regulating expression of PAX3. In addition, PAX3 expression was markedly higher in OS tissues than in adjacent non-cancerous tissues. Transwell assays and in vivo metastasis assays demonstrated that overexpression of PAX3 significantly promoted the invasiveness and pulmonary metastasis of OS cells. On the other hand, downregulation of PAX3 markedly reduced cell metastatic potential. Mechanistic investigations indicated that prometastasis function of PAX3 was mediated by upregulating downstream target MET tyrosine kinase receptor. In conclusion, our results reveal that miR-489-3p-PAX3-MET signaling is critical to OS metastasis. Targeting the pathway described here may open new therapeutic prospects to restrict the metastatic potential of OS. © 2016 Wiley Periodicals, Inc.

Liu Q ，Yang G ，Qian Y 《-》

MiR-223/Ect2/p21 signaling regulates osteosarcoma cell cycle progression and proliferation.

Osteosarcoma is one of the most common tumors. The mechanisms of formation and development of osteosarcoma have been studied for a long time. Recently, more and more evidence showed that miRNAs play important roles in regulating tumor growth. In this study we found that miRNA-223 was downregulated in both osteosarcoma patients' tumor tissues and osteosarcoma cell lines. Overexpression of miRNA-233 greatly inhibited the proliferation of Saos-2 cells. Cell cycle analysis by flow cytometry showed the arrest of cell cycle progression at the G1 phase. Further mechanistic study indicated that Ect2 was directly targeted by miR-223. Downregulation of Ect2 by miR-223 induces the expression of p21, p27 and the phospharylation of retinoblastoma, which are involved in the G1 block. We concluded that miR-223 functions as a tumor suppresser in osteosarcoma and miR-223/Ect2/p21 signaling is an important pathway that regulates the osteosarcoma cell cycle progression and proliferaion.

Xu J ，Yao Q ，Hou Y ，Xu M ，Liu S ，Yang L ，Zhang L ，Xu H ... -  《-》

MicroRNA-206 Reduces Osteosarcoma Cell Malignancy In Vitro by Targeting the PAX3-MET Axis.

This study was undertaken to explore how miR-206 represses osteosarcoma (OS) development. Expression levels of miR-206, PAX3, and MET mRNA were explored in paired OS and adjacent tissue specimens. A patient-derived OS cell line was established. miR-206 overexpression and knockdown were achieved by lentiviral transduction. PAX3 and MET overexpression were achieved by plasmid transfection. Treatment with hepatocyte growth factor (HGF) was utilized to activate c-Met receptor. Associations between miR-206 and PAX3 or MET mRNA in OS cells were verified by AGO2-RNA immunoprecipitation assay and miRNA pulldown assay. OS cell malignancy was evaluated in vitro by cell proliferation, metastasis, and apoptosis assays. PAX3 and MET gene expression in OS cells was assayed by RT-qPCR and Western blot. Activation of PI3K-AKT and MAPK-ERK in OS cells were assayed by evaluating Akt1 Ser473 phosphorylation and total threonine phosphorylation of Erk1/2, respectively. Expression levels of miR-206 were significantly decreased in OS tissue specimens, compared to adjacent counterparts, and were inversely correlated with expression of PAX3 and MET mRNA. miR-206 directly interacted with PAX3 and MET mRNA in OS cells. miR-206 overexpression significantly reduced PAX3 and MET gene expression in OS cells in vitro, resulting in significant decreases in Akt1 and Erk1/2 activation, cell proliferation, and metastasis, as well as increases in cell apoptosis, while miR-206 knockdown showed the opposite effects. The effects of miR-206 overexpression on OS cells were reversed by PAX3 or MET overexpression, but only partially attenuated by HGF treatment. miR-206 reduces OS cell malignancy in vitro by targeting PAX3 and MET gene expression.

Zhan FB ，Zhang XW ，Feng SL ，Cheng J ，Zhang Y ，Li B ，Xie LZ ，Deng QR ... -  《-》

[miR-365 inhibits proliferation and promotes apoptosis of SOSP9607 osteosarcoma cells].

Gao J ，Zhao P ，Chen X ，Wang W ，Li Y ，Xi W ，Zhang W ，Hu P ，Wang T ，Shan L ... -  《-》