Exosomes derived miR-454-3P to promote the progression of colorectal cancer via MIER1-mediated Notch signaling activation.

Abstract

e15108 Background: Mesoderm induction early response 1 (MIER1) was downregulated and predicted poor prognosis in CRC patients. However, the mechanisms of the down regulation of MIER1 in CRC remained unclear. Increasing evidence indicates that dysregulation of microRNAs promotes the progression of cancer through the repression of tumour suppressors.Here, we identified exosomes derived miR-454-3p as a novel regulator of MIER1 in CRC. Methods: The effect of miR-454-3p expression on cancer proliferation and metastasis was assessed in cells by altering the expression of miR-454-3p in vitro and in vivo. Mechanistic investigation was carried out by using cell and molecular biology approaches. Results: Functionally, ectopic expression or silencing of exosomes derived miR-454-3P, respectively, promoted or inhibited CRC cell proliferation, colony formation and cell cycle transition, as well as enhanced or prevented the invasion, metastasis of CRC cells and epithelial to mesenchymal transition of CRC cells in vitro and in vivo. Molecularly, exosomes derived miR-454-3P functioned as an onco-miRNA by activating the MIER1-regulated NOTCH pathway. Overexpression or silencing of MIER1 could partially reverse the effects of the overexpression or repression of exosomes derived miR-454-3P on CRC progress caused by activation of the NOTCH pathway in vitro and in vivo. Clinically, high miR-454-3P expression predicted poor survival in CRC patients, especially combined with low MIER1 expression. Conclusions: Collectively, we identified exosomes derived miR- 454-3p as an onco-miRNA, which acts by directly repressing MIER1 in CRC.