MicroRNA 483‐3p overexpression unleashes invasive growth of metastatic colorectal cancer via NDRG1 downregulation and ensuing activation of the ERBB3/AKT axis

In colorectal cancer, the mechanisms underlying tumor aggressiveness require further elucidation. Taking advantage of a large panel of human metastatic colorectal cancer xenografts and matched stem‐like cell cultures (m‐colospheres), here we show that the overexpression of microRNA 483‐3p (miRNA‐483‐3p; also known as MIR‐483‐3p), encoded by a frequently amplified gene locus, confers an aggressive phenotype. In m‐colospheres, endogenous or ectopic miRNA‐483‐3p overexpression increased proliferative response, invasiveness, stem cell frequency, and resistance to differentiation. Transcriptomic analyses and functional validation found that miRNA‐483‐3p directly targets NDRG1, known as a metastasis suppressor involved in EGFR family downregulation. Mechanistically, miRNA‐483‐3p overexpression induced the signaling pathway triggered by ERBB3, including AKT and GSK3β, and led to the activation of transcription factors regulating epithelial–mesenchymal transition (EMT). Consistently, treatment with selective anti‐ERBB3 antibodies counteracted the invasive growth of miRNA‐483‐3p‐overexpressing m‐colospheres. In human colorectal tumors, miRNA‐483‐3p expression inversely correlated with NDRG1 and directly correlated with EMT transcription factor expression and poor prognosis. These results unveil a previously unrecognized link between miRNA‐483‐3p, NDRG1, and ERBB3‐AKT signaling that can directly support colorectal cancer invasion and is amenable to therapeutic targeting. MicroRNA‐483‐3p (miRNA‐483‐3p) is a putative oncogene playing a still elusive role in colorectal cancer progression. We show that miRNA‐483‐3p directly targets NDRG1, known as a ‘metastasis suppressor’. Following NDRG1 downregulation, EGFR and ERBB3 signaling are unleashed, promoting retention of stemness features, epithelial–mesenchymal transition, and invasive growth. These properties can be counteracted by ERBB3 inhibition, offering a chance for therapeutic intervention.