title: Population Heterogeneity in the Epithelial to Mesenchymal Transition Is Controlled by NFAT and Phosphorylated Sp1.
abstract: Epithelial to mesenchymal transition (EMT) is an essential differentiation program during tissue morphogenesis and remodeling. EMT is induced by soluble transforming growth factor β (TGF-β) family members, and restricted by vascular endothelial growth factor family members. While many downstream molecular regulators of EMT have been identified, these have been largely evaluated individually without considering potential crosstalk. In this study, we created an ensemble of dynamic mathematical models describing TGF-β induced EMT to better understand the operational hierarchy of this complex molecular program. We used ordinary differential equations (ODEs) to describe the transcriptional and post-translational regulatory events driving EMT. Model parameters were estimated from multiple data sets using multiobjective optimization, in combination with cross-validation. TGF-β exposure drove the model population toward a mesenchymal phenotype, while an epithelial phenotype was enhanced following vascular endothelial growth factor A (VEGF-A) exposure. Simulations predicted that the transcription factors phosphorylated SP1 and NFAT were master regulators promoting or inhibiting EMT, respectively. Surprisingly, simulations also predicted that a cellular population could exhibit phenotypic heterogeneity (characterized by a significant fraction of the population with both high epithelial and mesenchymal marker expression) if treated simultaneously with TGF-β and VEGF-A. We tested this prediction experimentally in both MCF10A and DLD1 cells and found that upwards of 45% of the cellular population acquired this hybrid state in the presence of both TGF-β and VEGF-A. We experimentally validated the predicted NFAT/Sp1 signaling axis for each phenotype response. Lastly, we found that cells in the hybrid state had significantly different functional behavior when compared to VEGF-A or TGF-β treatment alone. Together, these results establish a predictive mechanistic model of EMT susceptibility, and potentially reveal a novel signaling axis which regulates carcinoma progression through an EMT versus tubulogenesis response.
authors.affiliation: Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York, United States of America.
authors.forename: Russell
authors.initials: R
authors.lastname: Gould
authors.affiliation: Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York, United States of America.
authors.forename: David M
authors.initials: DM
authors.lastname: Bassen
authors.affiliation: Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York, United States of America.
authors.forename: Anirikh
authors.initials: A
authors.lastname: Chakrabarti
authors.affiliation: Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York, United States of America.
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Varner
authors.affiliation: Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York, United States of America.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Butcher
mesh_terms: D002478:Cells, Cultured; D003198:Computer Simulation; D058750:Epithelial-Mesenchymal Transition / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D006801:Humans; D008954:Models, Biological; D009024:Morphogenesis / Q000502:physiology*; D050778:NFATC Transcription Factors / Q000378:metabolism*; D010766:Phosphorylation; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation / Q000502:physiology*
chemical_list: D050778:NFATC Transcription Factors; D016329:Sp1 Transcription Factor; C108209:SP1 protein, human; D014157:Transcription Factors