At present, a full understanding of the mechanisms by which colorectal cancer (CRC) distant metastases form is still beyond our reach because of the intricate regulation of gene expression. MicroRNAs (miRNAs) are shown to be involved in various human diseases including cancers through negative regulation of target gene expression at the post-transcriptional level. However, there are only a few studies on the roles of miRNA aberrations in liver metastasis of human colorectal cancer. To identify miRNA expression patterns associated with liver metastasis in human colorectal cancer, the miRNA expression profiles of colorectal cancer tissues with liver metastasis and their non-metastatic counterparts were studied using microRNA microarrays and further confirmed by quantitative RT-PCR. We show that 28 miRNAs are differentially expressed in the colorectal carcinomas with liver metastasis compared to the non-metastatic counterparts. Of these, 4 miRNAs including miR-150*, miR-125b-2*, miR-1179 and miR-139-3p were up-regulated in colorectal cancers with liver metastasis while the others were down-regulated. The target genes of selected deregulated miRNAs were predicted through bioinformatic techniques with two functional analyses, gene ontology and KEGG analysis, which showed that categories of high enrichment GOs and specific pathways targeted by dysregulated miRNAs were involved in liver metastasis during human colorectum carcinogenesis. Our results indicated that miRNAs are not only involved in carcinogenesis of colorectum, but may also participate in the progression such as with liver metastases in human colorectal cancers.

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