Project description:Experimental evidence accumulated over decades has implicated epithelial-mesenchymal plasticity (EMP), which collectively encompasses epithelial-mesenchymal transition and the reverse process of mesenchymal-epithelial transition, in tumour metastasis, cancer stem cell generation and maintenance, and therapeutic resistance. However, the dynamic nature of EMP processes, the apparent need to reverse mesenchymal changes for the development of macrometastases and the likelihood that only minor cancer cell subpopulations exhibit EMP at any one time have made such evidence difficult to accrue in the clinical setting. In this Perspectives article, we outline the existing preclinical and clinical evidence for EMP and reflect on recent controversies, including the failure of initial lineage-tracing experiments to confirm a major role for EMP in dissemination, and discuss accumulating data suggesting that epithelial features and/or a hybrid epithelial-mesenchymal phenotype are important in metastasis. We also highlight strategies to address the complexities of therapeutically targeting the EMP process that give consideration to its spatially and temporally divergent roles in metastasis, with the view that this will yield a potent and broad class of therapeutic agents.
Project description:Epithelial-mesenchymal plasticity (EMP) refers to the reversible cellular transition between epithelial and mesenchymal status. Spontaneous EMP is also reported in breast and prostate cancer, leading to the acquisition of stem-cell properties and chemoresistance. However, the presence of spontaneous EMP is still not reported in esophageal cancer. We screened 11 esophageal squamous cancer cell (ESCC) cell lines by CD44 isoform expression. KYSE520 was found to comprise heterogenous populations consisting of CD44v+ and CD44v- subpopulations. CD44v+ and CD44v- cells showed the expression of epithelial and mesenchymal markers, respectively. Single-cell sorting of CD44v+ and CD44v- cells revealed both cells gave rise to cell populations consisting of CD44v+ and CD44v- cells, indicating CD44v+ epithelial-like and CD44v- mesenchymal-like cells can generate counterparts, respectively. The ablation of Epithelial splicing regulatory protein 1 (ESRP1), a major regulator of CD44 mRNA splicing, resulted in the shift from CD44v+ to CD44v- cells in KYSE520. However, the expression of epithelial-mesenchymal transition (EMT)-related markers or transcriptional factors were almost not affected, suggesting ESRP1 functions downstream of EMP. Our results revealed the presence of spontaneous EMP in esophageal cancer and KYSE520 is useful model to understand spontaneous EMP.
Project description:The transition between epithelial and mesenchymal states has fundamental importance for embryonic development, stem cell reprogramming, and cancer progression. Here, we construct a topographic map underlying epithelial-mesenchymal transitions using a combination of numerical simulations of a Boolean network model and the analysis of bulk and single-cell gene expression data. The map reveals a multitude of metastable hybrid phenotypic states, separating stable epithelial and mesenchymal states, and is reminiscent of the free energy measured in glassy materials and disordered solids. Our work not only elucidates the nature of hybrid mesenchymal/epithelial states but also provides a general strategy to construct a topographic representation of phenotypic plasticity from gene expression data using statistical physics methods.
Project description:Epithelial-mesenchymal transition (EMT) is an important process in embryonic development, fibrosis, and cancer metastasis. During cancer progression, the activation of EMT permits cancer cells to acquire migratory, invasive, and stem-like properties. A growing body of evidence supports the critical link between EMT and cancer stemness. However, contradictory results have indicated that the inhibition of EMT also promotes cancer stemness, and that mesenchymal-epithelial transition, the reverse process of EMT, is associated with the tumor-initiating ability required for metastatic colonization. The concept of 'intermediate-state EMT' provides a possible explanation for this conflicting evidence. In addition, recent studies have indicated that the appearance of 'hybrid' epithelial-mesenchymal cells is favorable for the establishment of metastasis. In summary, dynamic changes or plasticity between the epithelial and the mesenchymal states rather than a fixed phenotype is more likely to occur in tumors in the clinical setting. Further studies aimed at validating and consolidating the concept of intermediate-state EMT and hybrid tumors are needed for the establishment of a comprehensive profile of cancer metastasis.
Project description:Epithelial to mesenchymal transition (EMT) and mesenchymal to epithelial transition (MET) are important interconnected events in tumorigenesis controlled by complex genetic networks. However, the cues that activate EMT-initiating factors and the mechanisms that reversibly connect EMT/MET are not well understood. Here, we show that cohesin-mediated chromatin organization coordinates EMT/MET by regulating mesenchymal genes. We report that RAD21, a subunit of the cohesin complex, is expressed in epithelial breast cancer cells, whereas its expression is decreased in mesenchymal cancer. Depletion of RAD21 in epithelial cancer cells causes transcriptional activation of TGFB1 and ITGA5, inducing EMT. Reduced binding of RAD21 changes intrachromosomal chromatin interactions within the TGFB1 and ITGA5 loci, creating an active transcriptional environment. Similarly, stem cell-like cancer cells also show an open chromatin structure at both genes, which correlates with high expression levels and mesenchymal fate characteristics. Conversely, overexpression of RAD21 in mesenchymal cancer cells induces MET-specific expression patterns. These findings indicate that dynamic cohesin-mediated chromatin structures are responsible for the initiation and regulation of essential EMT-related cell fate changes in cancer.
Project description:Epithelial-mesenchymal transition (EMT) is a fundamental process that occurs during embryogenesis and tissue repair. However, EMT can be hijacked by malignant cells, where it may promote immune evasion and metastasis. Classically considered a dichotomous transition, EMT in cancer has recently been considered a plastic process whereby malignant cells display and interconvert among hybrid epithelial/mesenchymal (E/M) states. Epithelial-mesenchymal plasticity (EMP) and associated hybrid E/M states are divergent from classical EMT, with unique immunomodulatory effects. Here, we review recent insights into the EMP-immune cross-talk, highlighting possible mechanisms of immune evasion conferred by hybrid E/M states and roles of immune cells in EMP.
Project description:Metabolic reprogramming and epithelial-mesenchymal plasticity are both hallmarks of the adaptation of cancer cells for tumor growth and progression. For metabolic changes, cancer cells alter metabolism by utilizing glucose, lipids, and amino acids to meet the requirement of rapid proliferation and to endure stressful environments. Dynamic changes between the epithelial and mesenchymal phenotypes through epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET) are critical steps for cancer invasion and metastatic colonization. Compared to the extensively studied metabolic reprogramming in tumorigenesis, the metabolic changes in metastasis are relatively unclear. Here, we review metabolic reprogramming, epithelial-mesenchymal plasticity, and their mutual influences on tumor cells. We also review the developing treatments for targeting cancer metabolism and the impact of metabolic targeting on EMT. In summary, understanding the metabolic adaption and phenotypic plasticity will be mandatory for developing new strategies to target metastatic and refractory cancers that are intractable to current treatments.
Project description:Tumor metastasis is the major cause of mortality and morbidity in most solid cancers. A growing body of evidence suggests that the epithelial-to-mesenchymal transition (EMT) plays a central role during tumor metastasis and frequently imparts a stem cell-like phenotype and therapeutic resistance to tumor cells. The induction of EMT is accompanied by a dynamic reprogramming of the epigenome involving changes in DNA methylation and several post-translational histone modifications. These changes in turn promote the expression of mesenchymal genes or repress those associated with an epithelial phenotype. Importantly, in order for metastatic colonization and the formation of macrometastases to occur, tumor cells frequently undergo a reversal of EMT referred to as the mesenchymal-to-epithelial transition (MET). Thus, a high degree of epigenetic plasticity is required in order to induce and reverse EMT during tumor progression. In this review, we describe various epigenetic regulatory mechanisms employed by tumor cells during EMT and elaborate on the importance of the histone code in controlling both the expression and activity of EMT-associated transcription factors. We propose that a more thorough understanding of the epigenetic mechanisms controlling EMT may provide new opportunities which may be harnessed for improved and individualized cancer therapy based on defined molecular mechanisms.
Project description:Triple-negative breast cancer (TNBC) is one of the most aggressive subtypes of breast cancer, with only limited treatment options available. Recently, cancer stem cells (CSCs) have emerged as the potential drivers of tumor progression due to their ability to both self-renew and give rise to differentiated progeny. The CSC state has been linked to the process of epithelial-mesenchymal transition (EMT) and to the highly flexible state of epithelial-mesenchymal plasticity (EMP). We aimed to establish primary breast cancer stem cell (BCSC) cultures isolated from TNBC specimens. These cells grow as tumor spheres under anchorage-independent culture conditions in vitro and reliably form tumors in mice when transplanted in limiting dilutions in vivo. The BCSC xenograft tumors phenocopy the original patient tumor in architecture and gene expression. Analysis of an EMT-related marker profile revealed the concomitant expression of epithelial and mesenchymal markers suggesting an EMP state for BCSCs of TNBC. Furthermore, BCSCs were susceptible to stimulation with the EMT inducer TGF-β1, resulting in upregulation of mesenchymal genes and enhanced migratory abilities. Overall, primary BCSC cultures are a promising model close to the patient that can be used both in vitro and in vivo to address questions of BCSC biology and evaluate new treatment options for TNBC.