The acquisition of mesenchymal traits is considered a hallmark of breast cancer progression. However, the functional relevance of epithelial-to-mesenchymal transition (EMT) remains controversial and context dependent. Here, we isolate epithelial and mesenchymal populations from human breast cancer metastatic biopsies and assess their functional potential in vivo. Strikingly, progressively decreasing epithelial cell adhesion molecule (EPCAM) levels correlate with declining disease propagation. Mechanistically, we find that persistent EPCAM expression marks epithelial clones that resist EMT induction and propagate competitively. In contrast, loss of EPCAM defines clones arrested in a mesenchymal state, with concomitant suppression of tumorigenicity and metastatic potential. This dichotomy results from distinct clonal trajectories impacting global epigenetic programs that are determined by the interplay between human ZEB1 and its target GRHL2. Collectively, our results indicate that susceptibility to irreversible EMT restrains clonal propagation, whereas resistance to mesenchymal reprogramming sustains disease spread in multiple models of human metastatic breast cancer, including patient-derived cells in vivo.
FörderungenSwiss Bridge Award Dietmar Hopp Foundation Max Eder Grant of the German Cancer Aid Organisation (Deutsche Kreb-shilfe) German Cancer Aid Organisation (Max-Eder Program) German Research Foundation (DFG) Federal Ministry of Education and Research, SATURN3 "Spatial and Temporal Resolution of Intratumoral Heterogeneity in 3 hard-to-treat Cancers Deutsche Forschungsgemeinschaft (DFG German Cancer Aid Organisation (Translational Oncology Program) German Research Foundation) European Research Council ETH Zurich strategic focus area of Personalized Health and Related Technologies at ETH Zurich Future and Emerging Technologies programme of the European Commission Swiss National Science Foundation Swiss Cancer League ETH Lymphoma Challenge