GSE61198
Distinct EMT programs control normal stem cells and cancer stem cells of mammary tissue
Cancer stem cells (CSCs) are proposed to be responsible for metastatic dissemination and clinical relapse in a variety of cancers. Analogies between CSCs and normal tissue stem cells (SC) has led to the notion that CSCs often co-opt the normal SC program of their tissue-of-origin. The cell-biological program termed epithelial-mesenchymal transition (EMT) has been found to encourage entrance of normal and neoplastic mammary cells into the corresponding SC states. Using genetically engineered knock-in reporter mouse lines, we demonstrate that in the murine mammary lineage, the paralogous EMT-inducing transcription factors Snail and Slug, are selectively exploited by CSCs and normal SCs respectively. Slug, when expressed at physiological levels, only activates a partial EMT program and is dispensable in CSCs. In contrast, Snail drives a far more complete transition into the mesenchymal state and controls both tumor-initiation and metastatic dissemination. Consistent with their functional distinctions, Snail controls far more target genes than Slug, and their distinct functions are determined by their divergent N-terminal domains. Our findings underscore fundamental distinctions between the SC program operating in normal and neoplastic SCs, and hint for potential avenues of selective therapeutic elimination of breast CSCs. Overall design: We sought to understand differential ability to activate the EMT program in breast cancer cells by transcription factors Snail and Slug. Hence, we mapped genome-wide Snail and Slug binding sites in murine MMTV-PyMT breast cancer cell lines that express high level of Snail or high level of Slug respectively. Specifically, we performed Snail ChIP seq in the mesenchymal pBl.3G cells, and Slug ChIP-seq in the epithelial pBl.1G cells.