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Critical Roles of p53 in Epithelial-Mesenchymal Transition and Metastasis of Hepatocellular Carcinoma Cells  [PDF]
Zheng Wang, Yuhui Jiang, Dongxian Guan, Jingjing Li, Hongkun Yin, Yi Pan, Dong Xie, Yan Chen
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0072846
Abstract: Hepatocellular carcinoma (HCC) is one of the most malignant tumors and the biggest obstacle in curing HCC is its high metastasis potential. Alteration of p53 is the most frequent genetic change found in HCC. Although the biological function of p53 in tumor initiation and progression has been well characterized, whether or not p53 is implicated in metastasis of HCC is largely unknown. In this study, we analyzed the potential functions of p53 in epithelial-mesenchymal transition (EMT) and metastasis of HCC cells. Both insulin- and TGF-β1-induced changes of critical EMT markers were greatly enhanced by p53 knockdown in HCC cells. The insulin- and TGF-β1-stimulated migration of HCC cells were enhanced by p53 knockdown. Furthermore, in vivo metastasis of HCC cells using different mouse models was robustly enhanced by p53 knockdown. In addition, we found that p53 regulation on EMT and metastasis involves β-catenin signaling. The nuclear accumulation and transcriptional activity of β-catenin was modulated by p53. The enhanced EMT phenotype, cell migration and tumor metastasis of HCC cells by p53 knockdown were abrogated by inhibiting β-catenin signal pathway. In conclusion, this study reveals that p53 plays a pivotal role in EMT and metastasis of HCC cells via its regulation on β-catenin signaling.
Inhibition of Breast Cancer Metastasis Suppressor 1 Promotes a Mesenchymal Phenotype in Lung Epithelial Cells That Express Oncogenic K-RasV12 and Loss of p53  [PDF]
Emily H. Hall, Yuan Liu, Aizhen Xiao, Lisa Shock, David L. Brautigan, Marty W. Mayo, Prasad S. Adusumilli, David R. Jones
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0095869
Abstract: Expression of the breast cancer metastasis suppressor 1 (BRMS1) protein is dramatically reduced in non-small cell lung cancer (NSCLC) cells and in primary human tumors. Although BRMS1 is a known suppressor of metastasis, the mechanisms through which BRMS1 functions to regulate cell migration and invasion in response to specific NSCLC driver mutations are poorly understood. To experimentally address this, we utilized immortalized human bronchial epithelial cells in which p53 was knocked down in the presence of oncogenic K-RasV12 (HBEC3-p53KD-K-RasV12). These genetic alterations are commonly found in NSCLC and are associated with a poor prognosis. To determine the importance of BRMS1 for cytoskeletal function, cell migration and invasion in our model system we stably knocked down BRMS1. Here, we report that loss of BRMS1 in HBEC3-p53KD-K-RasV12 cells results in a dramatic increase in cell migration and invasion compared to controls that expressed BRMS1. Moreover, the loss of BRMS1 resulted in additional morphological changes including F-actin re-distribution, paxillin accumulation at the leading edge of the lamellapodium, and cellular shape changes resembling mesenchymal phenotypes. Importantly, re-expression of BRMS1 restores, in part, cell migration and invasion; however it does not fully reestablish the epithelial phenotype. These finding suggests that loss of BRMS1 results in a permanent, largely irreversible, mesenchymal phenotype associated with increased cell migration and invasion. Collectively, in NSCLC cells without p53 and expression of oncogenic K-Ras our study identifies BRMS1 as a key regulator required to maintain a cellular morphology and cytoskeletal architecture consistent with an epithelial phenotype.
Epithelial-to-mesenchymal and mesenchymal-to-epithelial transitions in the colon  [cached]
Ferenc Sipos,Orsolya Galamb
World Journal of Gastroenterology , 2012, DOI: 10.3748/wjg.v18.i7.601
Abstract: Epithelial-to-mesenchymal and mesenchymal-to-epithelial transitions are well established biological events which have an important role in not just normal tissue and organ development, but in the pathogenesis of diseases. Increasing evidence has established their presence in the human colon during colorectal carcinogenesis and cancer invasion, chronic inflammation-related fibrosis and in the course of mucosal healing. A large body of evidence supports the role for transforming growth factor-β and its downstream Smad signaling, the phosphatidylinositol 3’-kinase/Akt/mTOR axis, the Ras-mitogen-activated protein kinase/Snail/Slug and FOXC2 pathway, and Hedgehog signaling and microRNAs in the development of colorectal cancers via epithelial-to-mesenchymal transition. C-met and Frizzled-7, among others, seem to be the principle effectors of mesenchymal-to-epithelial transition, hence have a role not just in mucosal regeneration but in the progression of colonic wall fibrosis. Here we discuss a role for these pathways in the initiation and development of the transition events. A better understanding of their induction and regulation may lead to the identification of pathways and factors that could be potent therapeutic targets. The inhibition of epithelial-to-mesenchymal transition using mTOR kinase inhibitors targeting the ATP binding pocket and which inhibit both mTORC1 and mTORC2, RNA aptamers or peptide mimetics, such as a Wnt5A-mimetic, may all be useful in both cancer treatment and delaying fibrosis, while the induction of mesenchymal-to-epithelial transition in induced pluripotent stem cells may enhance epithelial healing in the case of severe mucosal damage. The preliminary results of the current studies are promising, but more clinical investigations are needed to develop new and safe therapeutic strategies for diseases of the colon.
Epithelial–Mesenchymal Transition in Ovarian Carcinoma  [PDF]
Ben Davidson,Claes G. Tropé,Reuven Reich
Frontiers in Oncology , 2012, DOI: 10.3389/fonc.2012.00033
Abstract: Ovarian cancer is the most lethal gynecologic malignancy, with the majority of patients dying within 5 years of diagnosis. This poor survival of patients diagnosed with this malignancy is attributed to diagnosis at advanced stage, when the tumor has metastasized, and to chemotherapy resistance, either primary or developing along tumor progression. However, ovarian carcinomas, constituting the vast majority of ovarian cancers, additionally have unique biology, one aspect of which is the ability to co-express epithelial and mesenchymal determinants. epithelial–mesenchymal transition (EMT), a physiological process by which mesenchymal cells are formed and migrate to target organs during embryogenesis, is involved in cancer cell invasion and metastasis. However, these changes do not fully occur in ovarian carcinoma, and are even reversed in tumor cells present in malignant peritoneal and pleural effusions. This review summarizes current knowledge in this area, including the characteristics of EMT related to adhesion, transcriptional regulation and chemoresistance, and their clinical relevance, as well as the recently observed regulation of EMT by microRNA.
TGF-β1 induced epithelial to mesenchymal transition (EMT) in human bronchial epithelial cells is enhanced by IL-1β but not abrogated by corticosteroids
Astrid M Doerner, Bruce L Zuraw
Respiratory Research , 2009, DOI: 10.1186/1465-9921-10-100
Abstract: BEAS-2B and primary normal human bronchial epithelial cells were stimulated with TGFβ1 and expression of epithelial and mesenchymal markers assessed by quantitative real-time PCR, immunoblotting, immunofluorescence microscopy and zymography. In some cases the epithelial cells were also incubated with corticosteroids or IL-1β. Results were analyzed using non-parametric statistical tests.Treatment of BEAS-2B or primary human bronchial epithelial cells with TGFβ1 significantly reduced the expression level of the epithelial adherence junction protein E-cadherin. TGFβ1 then markedly induced mesenchymal marker proteins such as collagen I, tenascin C, fibronectin and α-smooth muscle actin mRNA in a dose dependant manner. The process of mesenchymal transition was accompanied by a morphological change towards a more spindle shaped fibroblast cell type with a more motile and invasive phenotype. Corticosteroid pre-treatment did not significantly alter the TGFβ1 induced transition but IL-1β enhanced the transition.Our results indicate, that TGFβ1 can induce mesenchymal transition in the bronchial epithelial cell line and primary cells. Since asthma has been strongly associated with increased expression of TGFβ1 in the airway, epithelial to mesenchymal transition may contribute to the contractile and fibrotic remodeling process that accompanies chronic asthma.Asthma is a chronic inflammatory disease of the airway, affecting approximately 10% of the general population [1]. Persistent asthma is characterized by structural changes termed airway remodeling. This ongoing remodeling and reconstruction of the asthmatic lung includes subepithelial fibrosis, myofibroblast hyperplasia, myocyte hyperplasia and/or hypertrophy, thickening of the lamina reticularis, and increased smooth muscle mass [2]. The more rapid decline in lung function over time in asthmatics is considered to be at least partly caused by this remodeling process. While the impact of corticosteroid treatment on airway re
Heterogeneity of expression of epithelial–mesenchymal transition markers in melanocytes and melanoma cell lines  [PDF]
Ji Eun Kim,Euphemia Leung,Bruce C. Baguley,Graeme J. Finlay
Frontiers in Genetics , 2013, DOI: 10.3389/fgene.2013.00097
Abstract: The epithelial–mesenchymal transition (EMT) describes a reversible switch from an epithelial-like to a mesenchymal-like phenotype. It is essential for the development of the normal epithelium and also contributes to the invasive properties of carcinomas. At the molecular level, the EMT transition is characterized by a series of coordinated changes including downregulation of the junctional protein E-cadherin (CDH1), up-regulation of transcriptional repressors of E-cadherin such as Snail (SNAI1) and Slug (SNAI2), and up-regulation of N-cadherin. We wished to determine whether cultured normal melanocytes and melanoma cell lines, which are derived from the neural crest, showed signs of a similarly coordinated phenotypic switch. We investigated normal melanocytes and 25 cell lines derived from New Zealand patients with metastatic melanoma. Most lines had been previously genotyped for common mutations such as BRAF, NRAS, PIK3CA (phosphatidylinositol-3-kinase), TP53 (p53), and CDKN2A (p16). Expression of E-cadherin, N-cadherin, microphthalmia-associated transcription factor (MITF), Snail, Slug, Axl, p53, and Hdm2 was compared by western blotting. Normal melanocytes expressed each of these proteins except for Snail, while normal melanocytes and almost every melanoma line expressed Slug. Expression of individual markers among different melanoma lines varied from high to low or undetectable. Quantitation of western blots showed that expression of MITF-M, the melanocyte-specific isoform of MITF, was positively related to that of E-cadherin but inversely related to that of N-cadherin and Axl. There was also no apparent relationship between expression of any particular marker and the presence of BRAF, NRAS, PIK3CA, TP53, or CDKN2A mutations. The results suggest that melanomas do not show the classical epithelial and mesenchymal phenotypes but rather display either high E-cadherin/high MITF-M expression on one hand, or high N-cadherin/high Axl expression on the other. These may correspond to differentiated and invasive phenotypes in vivo.
Epithelial to mesenchymal transition and breast cancer
Eva Tomaskovic-Crook, Erik W Thompson, Jean Thiery
Breast Cancer Research , 2009, DOI: 10.1186/bcr2416
Abstract: For almost two decades the prospect that recapitulation of the developmental process called epithelial to mesenchymal transition (EMT) may play an important role in carcinoma progression has been vigorously debated. Evidence of EMT from model systems supports further investigation of a potential new process to target the most insidious aspect of carcinoma - metastatic progression. However, evidence to demonstrate EMT in vivo has been controversial. We describe here recent developments in clinical studies alongside the latest findings from model systems pertinent to breast cancer progression, which strongly support the existence of EMT-like changes in breast carcinoma. Figure 1 illustrates examples of EMT processes in development and cancer. EMT marker expression is associated with poor prognosis in breast cancer, both at the individual gene product level and in basal subgroup demographics. Most importantly, cells isolated from breast carcinoma using protocols known to enrich for 'breast cancer stem cells' (BCSCs), which are dramatically more malignant than their non-BCSC counterparts, show clear evidence of EMT. The existence of EMT changes in clinical breast cancer places EMT at the center of malignancy. While presently there are no reports of mutations in important EMT regulators driving malignancy or disease progression, ensuing studies may clarify their involvement. Similarly, the EMT process is only starting to be specifically targeted for therapeutic benefit, although several current therapeutic targets are implicated in driving EMT. We anticipate that the growing acceptance of EMT will bring such translational advances in the coming years.Regulation of epithelial cell plasticity during EMT is increasingly implicated in the progression of carcinoma. Epithelial cells that undergo EMT lose their epithelial cell characteristics to acquire a mesenchymal phenotype and become migratory and invasive. Thus, EMT is characterized by cellular and molecular changes that i
Transcriptional Networks in Epithelial-Mesenchymal Transition  [PDF]
Christo Venkov,David Plieth,Terri Ni,Amitava Karmaker,Aihua Bian,Alfred L. George Jr,Eric G. Neilson
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0025354
Abstract: Epithelial-mesenchymal transition (EMT) changes polarized epithelial cells into migratory phenotypes associated with loss of cell-cell adhesion molecules and cytoskeletal rearrangements. This form of plasticity is seen in mesodermal development, fibroblast formation, and cancer metastasis.
Implications of the hybrid epithelial/mesenchymal phenotype in metastasis  [PDF]
Mohit Kumar Jolly,Marcelo Boareto,Bin Huang,Dongya Jia,Mingyang Lu,Jose N Onuchic,Herbert Levine,Eshel Ben-Jacob
Quantitative Biology , 2015,
Abstract: Understanding cell-fate decisions during tumorigenesis and metastasis is a major challenge in modern cancer biology. One canonical cell-fate decision that cancer cells undergo is Epithelial-to-Mesenchymal Transition (EMT) and its reverse Mesenchymal-to-Epithelial Transition (MET). While transitioning between these two phenotypes - epithelial and mesenchymal - cells can also attain a hybrid epithelial/mesenchymal (i.e. partial or intermediate EMT) phenotype. Cells in this phenotype have mixed epithelial (e.g. adhesion) and mesenchymal (e.g. migration) properties, thereby allowing them to move collectively as clusters of Circulating Tumor Cells (CTCs). If these clusters enter the circulation, they can be more apoptosis-resistant and more capable of initiating metastatic lesions than cancer cells moving individually with wholly mesenchymal phenotypes, having undergo a complete EMT. Here, we review the operating principles of the core regulatory network for EMT/MET that acts as a three-way switch giving rise to three distinct phenotypes - epithelial, mesenchymal and hybrid epithelial/mesenchymal. We further characterize this hybrid E/M phenotype in terms of its capabilities in terms of collective cell migration, tumor-initiation, cell-cell communication, and drug resistance. We elucidate how the highly interconnected coupling between these modules coordinates cell-fate decisions among a population of cancer cells in the dynamic tumor, hence facilitating tumor-stoma interactions, formation of CTC clusters, and consequently cancer metastasis. Finally, we discuss the multiple advantages that the hybrid epithelial/mesenchymal phenotype have as compared to a complete EMT phenotype and argue that these collectively migrating cells are the primary 'bad actors' of metastasis.
Hepatic regeneration and the epithelial to mesenchymal transition  [cached]
Zeng-Fu Xue,Xiu-Min Wu,Ming Liu
World Journal of Gastroenterology , 2013, DOI: 10.3748/wjg.v19.i9.1380
Abstract: Liver injuries are repaired by fibrosis and regeneration. The core stage is the repair response and fibrosis formation as a scar. The cause of overly-responsive scar formation and diminished regeneration, especially in liver fibrosis and cirrhosis, is still unknown. The epithelial to mesenchymal transition (EMT), a previously discovered mechanism, plays an important role in liver fibrosis and tumor metastasis. Recently, EMT has been found to be associated with liver and bile duct cell fibrosis. Analyzing the established models and chronic disease processes, we propose that EMT liver cells may also lose their regenerative capability due to phenotype changes and that the remaining liver cells may quickly lose their regenerative capability in liver fibrosis or cirrhosis. Recognizing these phenotype changes or transition cells may play an important role in targeting therapy to reverse fibrosis not only by disrupting the transition that is necessary to produce the extracellular matrix but also by restoring the regenerative capacity of EMT-like cells.
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