The role of the miR-200 family in epithelial-mesenchymal transition in colorectal cancer: a systematic review

Colorectal cancer (CRC) is associated with significant morbidity and mortality as many patients are diagnosed with advanced stage disease. MicroRNAs are small, noncoding RNA molecules that have a major role in gene expression regulation and are dysregulated in CRC. The miR-200 family is involved in epithelial-mesenchymal transition (EMT). This systematic review describes the roles of the miR-200 family in EMT in CRC. A search of electronic databases (PubMed and Embase) was conducted between January 2000 and July 2017. Both in vitro and human studies reporting on the miR-200 family and CRC were included. Studies describing molecular pathways and the role of the miR-200 family in the diagnostic and therapeutic management of CRC were analyzed. Thirty-four studies (22 in vitro and 18 human studies) were included. miR-200 family expression is regulated epigenetically and via transcriptional factor regulation. In vitro studies show that transfection of miR-200 family members into chemo-resistant colon cancer cell lines results in improved chemo-sensitivity and epithelial phenotype restoration. There is intra-tumoral variability in the tissue expression of miR-200 family members with decreased expression at the invasive front. Clinical studies in CRC patients have shown decreased primary tumor tissue expression of miR-429, miR-200a and miR-200c may be associated with worse survival. Conversely, increased blood levels of miR-141, miR-200a and miR-200c may be associated with worse outcomes. The miR-200 family has a central role in EMT. The miR200 family has potential for both prognostic and therapeutic management of CRC.