Epithelial to mesenchymal transition influences fibroblast phenotype in colorectal cancer by altering miR‐200 levels in extracellular vesicles

Colorectal cancer (CRC) with a mesenchymal gene expression signature has the greatest propensity for distant metastasis and is characterised by the accumulation of cancer‐associated fibroblasts in the stroma. We investigated whether the epithelial to mesenchymal transition status of CRC cells influences fibroblast phenotype, with a focus on the transfer of extracellular vesicles (EVs), as a controlled means of cell–cell communication. Epithelial CRC EVs suppressed TGF‐β‐driven myofibroblast differentiation, whereas mesenchymal CRC EVs did not. This was driven by miR‐200 (miR‐200a/b/c, ‐141), which was enriched in epithelial CRC EVs and transferred to recipient fibroblasts. Ectopic miR‐200 expression or ZEB1 knockdown, in fibroblasts, similarly suppressed myofibroblast differentiation. Supporting these findings, there was a strong negative correlation between miR‐200 and myofibroblastic markers in a cohort of CRC patients in the TCGA dataset. This was replicated in mice, by co‐injecting epithelial or mesenchymal CRC cells with fibroblasts and analysing stromal markers of myofibroblastic phenotype. Fibroblasts from epithelial tumours contained more miR‐200 and expressed less ACTA2 and FN1 than those from mesenchymal tumours. As such, these data provide a new mechanism for the development of fibroblast heterogeneity in CRC, through EV‐mediated transfer of miRNAs, and provide an explanation as to why CRC tumours with greater metastatic potential are CAF rich.