MicroRNA-508 defines the stem-like/mesenchymal subtype in colorectal cancer

Colorectal cancer (CRC) includes an invasive stem-like/mesenchymal subtype but its genetic drivers, functional and clinical relevance are uncharacterized. Here we report the definition of an altered microRNA (miR) signature defining this subtype which includes a major genomic loss of miR-508. Mechanistic investigations showed that this microRNA affected the expression of cadherin CDH1 and the transcription factors ZEB1, SALL4, BMI1 and BMI1. Loss of miR-508 in CRC was associated with upregulation of the novel hypoxia-induced long non-coding RNA AK000053. Ectopic expression of miR-508 in CRC cells blunted epithelial-mesenchymal transition (EMT), stemness, migration, and invasive capacity in vitro and in vivo. In clinical CRC specimens, expression of miRNA-508 negatively correlated with stemness and EMT-associated gene expression and inversely correlated with patient survival. Overall, our results showed that miRNA-508 is a key functional determinant of the stem-like/mesenchymal CRC subtype and a candidate therapeutic target for its treatment.

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