Pan-cancer EMT-signature identifies RBM47 down-regulation during colorectal cancer progression

Epithelial-mesenchymal transition (EMT) plays an important role in tumor invasion and metastasis. A comprehensive, bioinformatics analysis of CCLE and TCGA datasets of seven tumor types allowed us to identify a novel pan-cancer EMT-associated gene expression signature consisting of 16 epithelial and 4 mesenchymal state-associated mRNAs. Among the identified epithelial cell state-associated factors, down-regulation of the RBM47 (RNA binding motif protein 47) mRNA displayed the most significant association with metastasis and poor survival in multiple cohorts of colorectal cancer (CRC) patients. Moreover, decreased RBM47 protein expression was associated with metastasis in a cohort of primary CRCs. RBM47 was directly suppressed during EMT induced by IL6-activated STAT3 or ectopic SNAIL and SLUG expression via conserved binding motifs of these factors within the RBM47 promoter. Moreover, RNAi-mediated down-regulation of RBM47 in CRC lines resulted in increased cell migration, invasion and metastases formation. As demonstrated by the example of RBM47, the EMT-associated signature characterized here allows to identify biomarkers for predicting clinical outcome of CRC and presumably other cancer entities. In addition, our functional analysis of RBM47 shows that the down-regulation of RBM47 during CRC progression may promote EMT and metastasis.