EMT in mammary epithelial cells

The multi-step process of epithelial to mesenchymal transition (EMT), whereby static epithelial cells become migratory mesenchymal cells, is heavily involved in development, wound healing, and disease states. Despite the major involvement of basic helix-loop-helix (bHLH) transcription factors (TFs) in cell-fate determination, few have examined them for their involvement in fundamental processes that require EMT. Here, we have identified Max network transcription repressor (MNT) as a potent EMT promoting TF in mammary epithelium. We show that depletion of MNT blocked TGFb-induced phenotypic changes, and transcriptomic analysis revealed that MNT is a transcription repressor of epithelial identity. We show that MNT mediates repression of epithelial identity via direct interaction with HDAC1. Lastly, we show that MNT and its target genes are heavily expressed in EMT-High breast cancer, with MNT required for breast cancer cell migration. Taken together, these findings establish MNT as a critical regulator of cell-fate determination and the EMT transcriptome.