Interconnected feedback loops among ESRP1, HAS2, and CD44 regulate epithelial-mesenchymal plasticity in cancer.

Mohit Kumar Jolly,Satyendra C Tripathi,Dongya Jia,Samir M Hanash,Bogdan-Tiberius Preca,Jochen Maurer,Jason T George,Herbert Levine,Marc P Stemmler,Thomas Brabletz

doi:10.1063/1.5024874

Abstract

Aberrant activation of epithelial-mesenchymal transition (EMT) in carcinoma cells contributes to increased migration and invasion, metastasis, drug resistance, and tumor-initiating capacity. EMT is not always a binary process; rather, cells may exhibit a hybrid epithelial/mesenchymal (E/M) phenotype. ZEB1—a key transcription factor driving EMT—can both induce and maintain a mesenchymal phenotype. Recent studies have identified two novel autocrine feedback loops utilizing epithelial splicing regulatory protein 1 (ESRP1), hyaluronic acid synthase 2 (HAS2), and CD44 which maintain high levels of ZEB1. However, how the crosstalk between these feedback loops alters the dynamics of epithelial-hybrid-mesenchymal transition remains elusive. Here, using an integrated theoretical-experimental framework, we identify that these feedback loops can enable cells to stably maintain a hybrid E/M phenotype. Moreover, computational analysis identifies the regulation of ESRP1 as a crucial node, a prediction that is validated by experiments showing that knockdown of ESRP1 in stable hybrid E/M H1975 cells drives EMT. Finally, in multiple breast cancer datasets, high levels of ESRP1, ESRP1/HAS2, and ESRP1/ZEB1 correlate with poor prognosis, supporting the relevance of ZEB1/ESRP1 and ZEB1/HAS2 axes in tumor progression. Together, our results unravel how these interconnected feedback loops act in concert to regulate ZEB1 levels and to drive the dynamics of epithelial-hybrid-mesenchymal transition.

Highlights

We compared these transitions as mediated by the miR-200/Zinc finger E-box binding homeobox 1 (ZEB1)/epithelial splicing regulatory protein 1 (ESRP1)/hyaluronic acid synthase 2 (HAS2)/CD44 circuit, with the control case, i.e., when ZEB1 self-activation is not included through these detailed pathways but instead as in earlier modeling attempts
For certain SNAIL levels, cells can exhibit more than one phenotype and can spontaneously interconvert among one another, for instance, among E and M states in the {E, M} phase [green shaded region in Figs. 1(c) and 1(d)], among E, hybrid E/M, and M states in the {E, E/M, M} phase [brown shaded region in Figs. 1(c) and 1(d)], and among hybrid E/M and M states in the {E/M, M} phase [pink shaded region in Figs. 1(c) and 1(d)]. These results suggest that ZEB1 self-activation mediated by ESRP1/CD44 and HAS2/hyaluronic acid (HA)/CD44 axes should be considered integral to the dynamics of epithelial-hybrid-mesenchymal transition
Hyaluronan— known as hyaluronic acid (HA)—is a proteoglycan that forms a scaffold for the assembly of the extracellular matrix (ECM)

Summary

Introduction

The complex nonlinear behavior emerging from interconnected mechanical and chemical multi-scale regulatory feedback loops can modulate many parameters of aggressive cancer behavior such as metastasis, drug resistance, and tumor relapse.. Epithelial-mesenchymal transition (EMT) is a latent embryonic program that may become aberrantly activated during tumor progression and can regulate metastasis, drug resistance, evasion of the immune system, and tumor-initiation and relapse.. EMT can be induced by multiple micro-environmental conditions such as ECM stiffness and hypoxia which can activate one or more of EMT-driving transcription factors (EMT-TFs) such as ZEB (ZEB1/2), Snail (SNAI1/2), and Twist.. EMT-TFs such as ZEB1 can crosslink collagen in the ECM, altering mechanical stiffness of the ECM.. EMT acts as a hub in mediating the mechanochemical response of the tumor microenvironment (TME)

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Conclusion