miR-372 and miR-373 enhance the stemness of colorectal cancer cells by repressing differentiation signaling pathways.

miR-372/373, a cluster of stem cell-specific microRNAs transactivated by the Wnt pathway, has been reported to be dysregulated in various cancers, particularly colorectal cancer (CRC); however, the unique role of these microRNAs in cancer remains to be discovered. In the present study, we characterized the upregulation in expression of miR-372/373 in CRC tissues from The Cancer Genome Atlas data, and then showed that overexpression of miR-372/373 enhanced the stemness of CRC cells by enriching the CD26/CD24-positive cell population and promoting self-renewal, chemotherapy resistance and the invasive potential of CRC cells. To clarify the mechanism underlying microRNA-induced stemness, we profiled 45 cell signaling pathways in CRC cells overexpressing miR-372/373 and found that stemness-related pathways, such as Nanog and Hedgehog, were upregulated. Instead, differentiation-related pathways, such as NFκB, MAPK/Erk and VDR, were markedly repressed by miR-372/373. Numerous new targets of miR-372/373 were identified, including SPOP, VDR and SETD7, all of which are factors important for cell differentiation. Furthermore, in contrast to the increase in miR-372/373 expression in CRC tissues, the expression levels of SPOP and VDR mRNA were significantly downregulated in these tissues, indicative of the poor differentiation status of CRC. Taken together, our findings suggest that miR-372/373 enhance CRC cell stemness by repressing the expression of differentiation genes. These results provide new insights for understanding the function and mechanisms of stem cell-specific microRNAs in the development of metastasis and drug resistance in CRC.