miR-508 Defines the Stem-like/Mesenchymal Subtype in Colorectal Cancer

Colorectal cancer 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 miRNA signature defining this subtype that includes a major genomic loss of miR-508. Mechanistic investigations showed that this miRNA affected the expression of cadherin CDH1 and the transcription factors ZEB1, SALL4, and BMI1. Loss of miR-508 in colorectal cancer was associated with upregulation of the novel hypoxia-induced long noncoding RNA AK000053. Ectopic expression of miR-508 in colorectal cancer cells blunted epithelial- to-mesenchymal transition (EMT), stemness, migration, and invasive capacity in vitro and in vivo. In clinical colorectal cancer specimens, expression of miR-508 negatively correlated with stemness and EMT-associated gene expression and positively correlated with patient survival. Overall, our results showed that miR-508 is a key functional determinant of the stem-like/mesenchymal colorectal cancer subtype and a candidate therapeutic target for its treatment. Significance: These results define a key functional determinant of a stem-like/mesenchymal subtype of colorectal cancers and a candidate therapeutic target for its treatment. (C) 2018 AACR.