406958

MIR182

microRNA 182;MIR182;microRNA 182

hsa-mir-182

7q32.2

ncRNA

Transforming growth factor beta (TGF-beta) plays important roles in tumor metastasis by regulating miRNAs expression. miR-182 is an important molecule in the regulation of cancer progression. The aim of the study is to assess the role of miR-182 in TGF-beta-induced cancer metastasis. In the present study, we found that miR-182 levels are significantly upregulated in GBC tissues compared with normal controls, and miR-182 expression is remarkably increased in primary tumors that subsequently metastasized, when compared to those primary tumors that did not metastasize. TGF-beta induces miR-182 expression in GBC cells, and overexpression of miR-182 promotes GBC cell migration and invasion, whereas miR-182 inhibition suppresses TGF-beta-induced cancer cell migration and invasion. The blockage of miR-182 by a specific inhibitor effectively inhibits pulmonary metastases in vivo. We further identified that the cell adhesion molecule1 (CADM1) is a new target gene of miR-182. miR-182 negatively regulates CADM1 expression in vitro and in vivo. Importantly, re-expression of CADM1 in GBC cells partially abrogates miR-182-induced cell invasion. CONCLUSIONS: miR-182 is an important mediator of GBC metastasis, thus offering a new target for the development of therapeutic agents against GBC.

BACKGROUND: miR-182 is one of the most significantly up-regulated miRNAs in hepatocellular carcinoma (HCC). metastasis suppressor 1 (MTSS1), one target gene of miR-182, plays an important role in the metastasis of cancers. However, it remains unclear what role does function and mechanism of miR-182 and MTSS1play in HCC. METHODS: miR-182 expression was tested in 86 cases of paired HCC and normal tissues by real-time PCR and the relationships between miR-182 expression and clinicopathological parameters were analyzed. The expression of MTSS1 was evaluated by immunohistochemistry and western blot in the above tissues and its correlation with miR-182 expression was analyzed. Moreover, western blot and invasion assays were performed after transfection of pre-miR-182 or anti-miR-182 to HCC cell lines. In addition, luciferase assays was performed to confirm the regulation of miR-182 on MTSS1. RESULTS: Compared with normal tissue, miR-182 was up-regulated and MTSS1 was down-regulated in HCC tissues. Moreover, the over-expression of miR-182 was correlated with intrahepatic metastasis (p = 0.034) and poor prognosis (p = 0.039) of HCC patients. There was a negative correlation between miR-182 and MTSS1 expression in both HCC tissues (r = -0.673, p < 0.01) and HCC cell lines (r = -0.931, p = 0.021). Furthermore, the up-regulation of miR-182 resulted in the down-regulation of MTSS1 and increased invasive potential of HUH-1, and reverse results were also confirmed when the expression of miR-182 was inhibited. In addition, the results of the luciferase assay demonstrated the targeted regulation of miR-182 on MTSS1. CONCLUSIONS: miR-182 could promote metastasis of HCC and inhibit the expression of MTSS1. miR-182 and MTSS1 are potential prognostic markers and/or therapeutic targets in HCC.

The highly aggressive character of melanoma makes it an excellent model for probing the mechanisms underlying metastasis, which remains one of the most difficult challenges in treating cancer. We find that miR-182, member of a miRNA cluster in a chromosomal locus (7q31-34) frequently amplified in melanoma, is commonly up-regulated in human melanoma cell lines and tissue samples; this up-regulation correlates with gene copy number in a subset of melanoma cell lines. Moreover, miR-182 ectopic expression stimulates migration of melanoma cells in vitro and their metastatic potential in vivo, whereas miR-182 down-regulation impedes invasion and triggers apoptosis. We further show that miR-182 over-expression promotes migration and survival by directly repressing microphthalmia-associated transcription factor-M and FOXO3, whereas enhanced expression of either microphthalmia-associated transcription factor-M or FOXO3 blocks miR-182's proinvasive effects. In human tissues, expression of miR-182 increases with progression from primary to metastatic melanoma and inversely correlates with FOXO3 and microphthalmia-associated transcription factor levels. Our data provide a mechanism for invasion and survival in melanoma that could prove applicable to metastasis of other cancers and suggest that miRNA silencing may be a worthwhile therapeutic strategy.

metastasis causes most cancer deaths, but is incompletely understood. MicroRNAs can regulate metastasis, but it is not known whether a single miRNA can regulate metastasis in primary cancer models in vivo. We compared the expression of miRNAs in metastatic and nonmetastatic primary mouse sarcomas and found that microRNA-182 (miR-182) was markedly overexpressed in some tumors that metastasized to the lungs. By utilizing genetically engineered mice with either deletion of or overexpression of miR-182 in primary sarcomas, we discovered that deletion of miR-182 substantially decreased, while overexpression of miR-182 considerably increased, the rate of lung metastasis after amputation of the tumor-bearing limb. Additionally, deletion of miR-182 decreased circulating tumor cells (CTCs), while overexpression of miR-182 increased CTCs, suggesting that miR-182 regulates intravasation of cancer cells into the circulation. We identified 4 miR-182 targets that inhibit either the migration of tumor cells or the degradation of the extracellular matrix. Notably, restoration of any of these targets in isolation did not alter the metastatic potential of sarcoma cells injected orthotopically, but the simultaneous restoration of all 4 targets together substantially decreased the number of metastases. These results demonstrate that a single miRNA can regulate metastasis of primary tumors in vivo by coordinated regulation of multiple genes.