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Transcriptional regulation of miR-224 upregulated in human HCCs by NF魏B inflammatory pathways
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摘要
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Background & Aims

miR-224 is up-regulated in human HCCs as compared to both paired peri-tumoral cirrhotic tissues and cirrhotic livers without HCC. Here, we have cloned the miR-224 regulatory region and characterized its transcriptional regulation by the NF魏B-dependent inflammatory pathways.

Methods

Mature miRNA expression was evaluated by a 2 step stem-loop real-time RT-PCR. The recruitment of polymerase II and transcription factors on the pre-miR-224 promoter has been assessed by ChIPSeq and ChIP.

Results

We found miR-224 levels strongly up-regulated in both peri-tumoral cirrhotic livers and HCC samples as compared to normal livers. In silico analysis of the putative miR-224 promoter revealed multiple NFB sites. We showed that LT伪 and TNF伪 activate transcription from the miR-224 promoter and of endogenous miR-224 expression in HCC cell lines, whereas the expression of miR-224 target API5 was reduced. Exogenously expressed p65/RelA activates the miR-224 promoter and a dominant negative form of IB伪 (IBSR) represses it. ChIP analysis showed that p65/NFB is recruited on the miR-224 promoter and that its binding sharply increases after exposure to LPS, TNF伪, and LT伪. Altogether these findings link the inflammatory signals to NFB-mediated activation of miR-224 expression. An antago-miR specific for miR-224 blocked LPS and LT伪 stimulated HCC cells migration and invasion. Conversely, the IKK inhibitor BMS-345541 blocks pre-miR-224-induced cellular migration and invasion.

Conclusions

Our results identify p65/NFB as a direct transcriptional regulator of miR-224 expression and link miR-224 up-regulation with the activation of the LPS, LT伪, and TNF伪 inflammatory pathways and cell migration/invasion in HCC.

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