Target cell movement in tumor and cardiovascular diseases based on the epithelial-mesenchymal transition concept

Dipeptidase‑2 is a prognostic marker in lung adenocarcinoma that is correlated with its sensitivity to cisplatin

Lung cancer accounts for the highest percentage of cancer morbidity and mortality worldwide, and lung adenocarcinoma (LUAD) is the most prevalent subtype. Although numerous therapies have been developed for lung cancer, patient prognosis is limited by tumor metastasis and more effective treatment targets are urgently required. In the present study, gene expression profiles were extracted from the Gene Expression Omnibus database and mRNA expression data were downloaded from The Cancer Genome Atlas database. In addition, TIMER 2.0 database was used to analyze the expression of genes in normal and multiple tumor tissues. Protein expression was confirmed using the Human Protein Atlas database and LUAD cell lines, sphere formation assay, western blotting, and a xenograft mouse model were used to confirm the bioinformatics analysis. Dipeptidase‑2 (DPEP2) expression was significantly decreased in LUAD and was negatively associated with prognosis. DPEP2 overexpression substantially inhibited epithelial‑mesenchymal transition (EMT) as well as LUAD cell metastasis, and limited the expression of the cancer stem cell transformation markers, CD44 and CD133. In addition, DPEP2 improved LUAD sensitivity to cisplatin by inhibiting EMT; this was verified in vitro and in vivo. These data indicated that DPEP2 upregulates E‑cadherin, thereby regulating cell migration, cancer stem cell transformation, and cisplatin resistance, ultimately affecting the survival of patients with LUAD. Overall, the findings of the present suggest that DPEP2 is important in the development of LUAD and can be used both as a prognostic marker and a target for future therapeutic research.

Investigation of role of CpG methylation in some epithelial mesenchymal transition gene in a chemoresistant ovarian cancer cell line

Ovarian cancer is one of the lethal gynecologic cancers. Chemoresistance is an essential reason for treatment failure and high mortality. Emerging evidence connects epithelial-mesenchymal transition (EMT) like changes and acquisition of chemoresistance in cancers. Including EMT, DNA methylation influences cellular processes. Here, EMT-like changes were investigated in cisplatin-resistant A2780 ovarian cancer cells (A2780cis), wherein role of DNA methylation in some EMT genes regulations was studied. Cell viability assay was carried out to test the sensitivity of A2780, and A2780cis human cancer cell lines to cisplatin. Differential mRNA expression of EMT markers using qPCR was conducted to investigate EMT like changes. CpG methylation role in gene expression regulation was investigated by 5-azacytidine (5-aza) treatment. DNA methylation changes in EMT genes were identified using Methylscreen assay between A2780 and A2780cis cells. In order to evaluate if DNA methylation changes are causally underlying EMT, treatment with 5-aza followed by Cisplatin was done on A2780cis cells. Accordingly, morphological changes were studied under the microscope, whereas EMT marker's gene expression changes were investigated using qPCR. In this respect, A2780cis cell line has maintained its cisplatin tolerance ability and exhibits phenotypic changes congruent with EMT. Methylscreen assay and qPCR study have revealed DNA hypermethylation in promoters of epithelial adhesion molecules CDH1 and EPCAM in A2780cis compared to the cisplatin-sensitive parental cells. These changes were concomitant with gene expression down-regulation. DNA hypomethylation associated with transcription up-regulation of the mesenchymal marker TWIST2 was observed in the resistant cells. Azacytidine treatment confirmed DNA methylation role in regulating gene expression of CDH1, EPCAM and TWIST2 genes. A2780cis cell line undergoes EMT like changes, and EMT genes are regulated by DNA methylation. To that end, a better understanding of the molecular alterations that correlate with chemoresistance may lead to therapeutic benefits such as chemosensitivity restoration.

Embryonic Chicken (Gallus gallus domesticus) as a Model of Cardiac Biology and Development

Cardiovascular disease remains one of the top contributors to morbidity and mortality in the United States. Increasing evidence suggests that many processes, pathways, and programs observed during development and organogenesis are recapitulated in adults in the face of disease. Therefore, a heightened understanding of cardiac development and organogenesis will help increase our understanding of developmental defects and cardiovascular diseases in adults. Chicks have long served as a model system in which to study developmental problems. Detailed descriptions of morphogenesis, low cost, accessibility, ease of manipulation, and the optimization of genetic engineering techniques have made chicks a robust model for studying development and make it a powerful platform for cardiovascular research. This review summarizes the cardiac developmental milestones of embryonic chickens, practical considerations when working with chicken embryos, and techniques available for use in chicks (including tissue chimeras, genetic manipulations, and live imaging). In addition, this article highlights examples that accentuate the utility of the embryonic chicken as model system in which to study cardiac development, particularly epicardial development, and that underscore the importance of how studying development informs our understanding of disease.

The FZD7-TWIST1 axis is responsible for anoikis resistance and tumorigenesis in ovarian carcinoma

Frizzled family receptor 7 (FZD7), a Wnt signaling receptor, is associated with the maintenance of stem cell properties and cancer progression. FZD7 has emerged as a potential therapeutic target because it is capable of transducing both canonical and noncanonical Wnt signals. In this study, we investigated the regulatory pathway downstream of FZD7 and its functional roles. We found that FZD7 expression was crucial to the maintenance of the mesenchymal phenotype, anoikis resistance, and spheroid and tumor formation in ovarian cancer (OC). We identified TWIST1 as the crucial downstream effector of the FZD7 pathway. TWIST1, a basic helix loop helix transcription factor, is known to associate with mesenchymal and cancer stem cell phenotypes. Manipulating TWIST1 expression mimicked the functional consequences observed in the FZD7 model, and overexpression of TWIST1 partially rescued the functional phenotypes abolished by FZD7 knockdown. We further proved that FZD7 regulated TWIST1 expression through epigenetic modifications of H3K4me3 and H3K27ac at the TWIST1 proximal promoter. We also identified that the FZD7‐TWIST1 axis regulates the expression of BCL2, a gene that controls apoptosis. Identification of this FZD7‐TWIST1‐BCL2 pathway reaffirms the mechanism of anoikis resistance in OC. We subsequently showed that the FZD7‐TWIST1 axis can be targeted by using a small molecule inhibitor of porcupine, an enzyme essential for secretion and functional activation of Wnts. In conclusion, our results identified that the FZD7‐TWIST1 axis is important for tumorigenesis and anoikis resistance, and therapeutic inhibition results in cell death in OCs.

Proteinase-activated receptor 2 promotes tumor cell proliferation and metastasis by inducing epithelial-mesenchymal transition and predicts poor prognosis in hepatocellular carcinoma

AIM

To clarify the role of proteinase-activated receptor 2 (PAR2) in hepatocellular carcinoma, especially in the process of metastasis.

METHODS

PAR2 expression levels were assessed by qRT-PCR and immunohistochemistry (IHC) in patient tissues and in hepatocellular carcinoma cell lines SMMC-7721 and HepG2. Cell proliferation and metastasis were assessed both in vitro and in vitro. Immunoblotting was carried out to monitor the levels of mitogen-activated protein kinase (MAPK) and epithelial-mesenchymal transition markers.

RESULTS

The prognosis was significantly poorer in patients with high PAR2 levels than in those with low PAR2 levels. Patients with high PAR2 levels had advanced tumor stage (P = 0.001, chi-square test), larger tumor size (P = 0.032, chi-square test), and high microvascular invasion rate (P = 0.037, chi-square test). The proliferation and metastasis ability of SMMC-7721 and HepG2 cells was increased after PAR2 overexpression, while knockdown of PAR2 decreased the proliferation and metastasis ability of SMMC-7721 and HepG2 cells. Knockdown of PAR2 also inhibited hepatocellular carcinoma tumor cell growth and liver metastasis in nude mice. Mechanistically, PAR2 increased the proliferation ability of SMMC-7721 and HepG2 cells via ERK activation. Activated ERK further promoted the epithelial-mesenchymal transition of these cells, which endowed them with enhanced migration and invasion ability.

CONCLUSION

These data suggest that PAR2 plays an important role in the proliferation and metastasis of hepatocellular carcinoma. Therefore, targeting PAR2 may present a favorable target for treatment of this malignancy.

Expression of proteins associated with epithelial-mesenchymal transition in esophageal squamous cell carcinoma

Cluster of differentiation 147 (CD147), pituitary tumor transforming gene (PTTG) and CD44v6 are proteins involved in the epithelial-mesenchymal transition (EMT). To investigate the prognostic value of CD147 and PTTG, and CD44v6 expression in esophageal squamous cell carcinoma (ESCC), tissue microarray specimens from 76 patients with ESCC were evaluated by immunohistochemistry staining and scored by intensity and proportion of positive areas. Expression levels of CD147, PTTG and CD44v6 were higher in tumor tissues than in matched adjacent tissues. CD147 expression was positively associated with lymph node metastasis (P=0.025) and American Joint Committee on Cancer (AJCC) system clinical grades (P=0.037). CD147 expression was positively correlated with the expression levels of PTTG (R=0.369; P=0.001) and CD44v6 (R=0.320; P=0.005). In addition, Kaplan-Meier analysis indicated that positive expression of CD147, PTTG and CD44v6 was significantly associated with poor overall survival times (P=0.045, P=0.014 and P=0.027, respectively). Patients exhibiting CD147-PTTG co-expression, CD147-CD44v6 co-expression and CD147-PTTG-CD44v6 triple-positive expression had the poorest overall survival rates. In conclusion, the expression of EMT-associated proteins, including CD147, PTTG and CD44v6, was significantly associated with poor survival in ESCC and these novel targets may serve as potential biomarkers for anticancer therapies.

Suppression of CIP4/Par6 attenuates TGF-β1-induced epithelial-mesenchymal transition in NRK-52E cells

Transforming growth factor-β (TGF-β) induces epithelial-mesenchymal transition (EMT) primarily via a Smad-dependent mechanism. However, there are few studies available on TGF-β-induced EMT through the activation of non-canonical pathways. In this study, the Cdc42-interacting protein-4 (CIP4)/partitioning-defective protein 6 (Par6) pathway was investigated in TGF-β1-stimulated NRK-52E cells. Rat NRK-52E cells were obtained and stimulated with TGF-β1. The expression levels of E-cadherin, α-smooth muscle actin (α-SMA) and CIP4 were then examined by western blot analyses. Rat NRK-52E cells were transfected with Par6 or CIP4 small interfering RNA (siRNA), and scrambled siRNA as controls. The cells were incubated with 20 ng/ml of TGF-β1 for 72 h in order to observe the effects of Par6 and CIP4 silencing. Confocal fluorescence microscopy was also applied to reveal the expression and distribution of E-cadherin, α-SMA, Par6 and CIP4. The results demonstrated that E-cadherin expression was decreased, and α-SMA expression was increased in the TGF-β1-stimulated cells. Simultaneously, the increased expression of CIP4 and p-Par6 was confirmed by western blot analyses. The results of confocal fluorescence microscopy revealed that rat CIP4 exhibited cluster formations located adjacent to the cell periphery; however, as for the protein expression and distribution of Par6, there was no obvious difference between the control cells and cells exposed to TGF-β1. siRNA molecules capable of CIP4 and Par6 knockdown were used to demonstrate reversed TGF-β1-induced EMT. Moreover, CIP4 loss of function reversed the increase in p-Par6 protein expression in the TGF-β1-stimulated NRK-52E cells. A similar result was observed with the decreased CIP4 protein expression due to Par6 loss of function. Our data thus suggest that the CIP4/Par6 complex plays an important role in the occurrence of EMT in TGF-β1-stimulated NRK-52E cells. The underlying mechanisms are mediated, at least in part, through the upregulation of CIP4, which occurrs due to stimulation with TGF-β1; subsequently, CIP4 increases the phosphorylation of Par6, which accelerates the process of EMT.

Stem Cell Spheroids and Ex Vivo Niche Modeling: Rationalization and Scaling-Up

Improved protocols/devices for in vitro culture of 3D cell spheroids may provide essential cues for proper growth and differentiation of stem/progenitor cells (S/PCs) in their niche, allowing preservation of specific features, such as multi-lineage potential and paracrine activity. Several platforms have been employed to replicate these conditions and to generate S/PC spheroids for therapeutic applications. However, they incompletely reproduce the niche environment, with partial loss of its highly regulated network, with additional hurdles in the field of cardiac biology, due to debated resident S/PCs therapeutic potential and clinical translation. In this contribution, the essential niche conditions (metabolic, geometric, mechanical) that allow S/PCs maintenance/commitment will be discussed. In particular, we will focus on both existing bioreactor-based platforms for the culture of S/PC as spheroids, and on possible criteria for the scaling-up of niche-like spheroids, which could be envisaged as promising tools for personalized cardiac regenerative medicine, as well as for high-throughput drug screening.

EMT: 2016

The significant parallels between cell plasticity during embryonic development and carcinoma progression have helped us understand the importance of the epithelial-mesenchymal transition (EMT) in human disease. Our expanding knowledge of EMT has led to a clarification of the EMT program as a set of multiple and dynamic transitional states between the epithelial and mesenchymal phenotypes, as opposed to a process involving a single binary decision. EMT and its intermediate states have recently been identified as crucial drivers of organ fibrosis and tumor progression, although there is some need for caution when interpreting its contribution to metastatic colonization. Here, we discuss the current state-of-the-art and latest findings regarding the concept of cellular plasticity and heterogeneity in EMT. We raise some of the questions pending and identify the challenges faced in this fast-moving field.

Functional relevance of a six mesenchymal gene signature in epithelial-mesenchymal transition (EMT) reversal by the triple angiokinase inhibitor, nintedanib (BIBF1120)

Epithelial-mesenchymal transition (EMT), a crucial mechanism in carcinoma progression, describes the process whereby epithelial cells lose their apico-basal polarity and junctional complexes and acquire a mesenchymal-like morphology. Several markers are considered to be authentic indicators of an epithelial or mesenchymal status; however, there is currently no comprehensive or systematic method with which to determine their functional relevance. Previously, we identified a 33-gene EMT signature comprising 25 epithelial and 6 mesenchymal genes that best describe this concept of the EMT spectrum. Here, we designed small-scale siRNA screens targeting these six mesenchymal signature genes (CD99L2, EMP3, ITGA5, SYDE1, VIM, ZEB1) to explore their functional relevance and their roles during EMT reversal by nintedanib (BIBF1120) in a mesenchymal-like SKOV3 ovarian cancer cell line. We found that neither cell proliferation nor cytotoxicity was affected by silencing any of these genes. SKOV3 cells expressing siRNA against mesenchymal genes (ZEB1, EMP3, CD99L2, ITGA5, and SYDE1) showed enhanced colony compaction (reduced inter-nuclear distance). Inductions of E-cadherin expression were only observed in SYDE1- and ZEB1-silenced SKOV3 cells. In addition, only SYDE1-silenced SKOV3 cells showed increased anoikis. Finally, we identified that SYDE1 and ZEB1 were down-regulated in nintedanib-treated SKOV3 cells and SYDE1- and ZEB1-silenced SKOV3 cells showed enhanced nintedanib-induced up-regulation of E-cadherin. Nintedanib-treated SKOV3 cells also showed colony compaction and decreases in EMT scores both in vitro and in vivo. We conclude that SYDE1 and ZEB1 are functionally relevant in EMT reversal. This study thus provides a proof-of-concept for the use of in vitro siRNA screening to explore the EMT-related functions of selected genes and their potential relevance in the discovery of EMT reversing drugs.

Combinatorial treatment using targeted MEK and SRC inhibitors synergistically abrogates tumor cell growth and induces mesenchymal-epithelial transition in non-small-cell lung carcinoma

Oncogenesis in non-small cell lung cancer (NSCLC) is regulated by a complex signal transduction network. Single-agent targeted therapy fails frequently due to treatment insensitivity and acquired resistance. In this study, we demonstrate that co-inhibition of the MAPK and SRC pathways using a PD0325901 and Saracatinib kinase inhibitor combination can abrogate tumor growth in NSCLC. PD0325901/Saracatinib at 0.25:1 combination was screened against a panel of 28 NSCLC cell lines and 68% of cell lines were found to be sensitive (IC₅₀ < 2 μM) to this combination. In Snail1 positive NSCLC lines, the drug combination complementarily enhanced mesenchymal-epithelial transition (MET), increasing both E-cadherin and Plakoglobin expression, and reducing Snail1, FAK and PXN expression. In addition, the drug combination abrogated cell migration and matrigel invasion. The co-inhibition of MAPK and SRC induced strong G1/G0 cell cycle arrest in the NSCLC lines, inhibited anchorage independent growth and delayed tumor growth in H460 and H358 mouse xenografts. These data provide rationale for further investigating the combination of MAPK and SRC pathway inhibitors in advanced stage NSCLC.

An epithelial marker promoter induction screen identifies histone deacetylase inhibitors to restore epithelial differentiation and abolishes anchorage independence growth in cancers

Epithelial–mesenchymal transition (EMT), a crucial mechanism in development, mediates aggressiveness during carcinoma progression and therapeutic refractoriness. The reversibility of EMT makes it an attractive strategy in designing novel therapeutic approaches. Therefore, drug discovery pipelines for EMT reversal are in need to discover emerging classes of compounds. Here, we outline a pre-clinical drug screening platform for EMT reversal that consists of three phases of drug discovery and validation. From the Phase 1 epithelial marker promoter induction (EpI) screen on a library consisting of compounds being approved by Food and Drug Administration (FDA), Vorinostat (SAHA), a histone deacetylase inhibitor (HDACi), is identified to exert EMT reversal effects by restoring the expression of an epithelial marker, E-cadherin. An expanded screen on 41 HDACi further identifies 28 compounds, such as class I-specific HDACi Mocetinosat, Entinostat and CI994, to restore E-cadherin and ErbB3 expressions in ovarian, pancreatic and bladder carcinoma cells. Mocetinostat is the most potent HDACi to restore epithelial differentiation with the lowest concentration required for 50% induction of epithelial promoter activity (EpIC-50).The HDACi exerts paradoxical effects on EMT transcriptional factors such as SNAI and ZEB family and the effects are context-dependent in epithelial- and mesenchymal-like cells. In vitro functional studies further show that HDACi induced significant increase in anoikis and decrease in spheroid formation in ovarian and bladder carcinoma cells with mesenchymal features. This study demonstrates a robust drug screening pipeline for the discovery of compounds capable of restoring epithelial differentiation that lead to significant functional lethality.

Noncanonical roles of membranous lysyl-tRNA synthetase in transducing cell-substrate signaling for invasive dissemination of colon cancer spheroids in 3D collagen I gels

The adhesion properties of cells are involved in tumor metastasis. Although KRS at the plasma membrane is shown important for cancer metastasis, additionally to canonical roles of cytosolic KRS in protein translation, how KRS and its downstream effectors promote the metastatic migration remains unexplored. Disseminative behaviors (an earlier metastatic process) of colon cancer cell spheroids embedded in 3D collagen gels were studied with regards to cell adhesion properties, and relevance in KRS^−/+ knocked-down animal and clinical colon cancer tissues. Time-lapse imaging revealed KRS-dependent cell dissemination from the spheroids, whereas KRS-suppressed spheroids remained static due to the absence of outbound movements supported by cell-extracellular matrix (ECM) adhesion. While keeping E-cadherin at the outward disseminative cells, KRS caused integrin-involved intracellular signaling for ERK/c-Jun, paxillin, and cell-ECM adhesion-mediated signaling to modulate traction force for crawling movement. KRS-suppressed spheroids became disseminative following ERK or paxillin re-expression. The KRS-dependent intracellular signaling activities correlated with the invasiveness in clinical colon tumor tissues and in KRS^−/+ knocked-down mice tissues. Collectively, these observations indicate that KRS at the plasma membrane plays new roles in metastatic migration as a signaling inducer, and causes intracellular signaling for cancer dissemination, involving cell-cell and cell-ECM adhesion, during KRS-mediated metastasis.

Suppression of lysyl-tRNA synthetase, KRS, causes incomplete epithelial-mesenchymal transition and ineffective cell‑extracellular matrix adhesion for migration

The cell-adhesion properties of cancer cells can be targeted to block cancer metastasis. Although cytosolic lysyl-tRNA synthetase (KRS) functions in protein synthesis, KRS on the plasma membrane is involved in cancer metastasis. We hypothesized that KRS is involved in cell adhesion-related signal transduction for cellular migration. To test this hypothesis, colon cancer cells with modulated KRS protein levels were analyzed for cell-cell contact and cell-substrate adhesion properties and cellular behavior. Although KRS suppression decreased expression of cell-cell adhesion molecules, cells still formed colonies without being scattered, supporting an incomplete epithelial mesenchymal transition. Noteworthy, KRS-suppressed cells still exhibited focal adhesions on laminin, with Tyr397-phopshorylated focal adhesion kinase (FAK), but they lacked laminin-adhesion-mediated extracellular signal-regulated kinase (ERK) and paxillin activation. KRS, p67LR and integrin α6β1 were found to interact, presumably to activate ERK for paxillin expression and Tyr118 phosphorylation even without involvement of FAK, so that specific inhibition of ERK or KRS in parental HCT116 cells blocked cell-cell adhesion and cell-substrate properties for focal adhesion formation and signaling activity. Together, these results indicate that KRS can promote cell-cell and cell-ECM adhesion for migration.

Mechanistic adaptability of cancer cells strongly affects anti-migratory drug efficacy

Cancer metastasis involves the dissemination of cancer cells from the primary tumour site and is responsible for the majority of solid tumour-related mortality. Screening of anti-metastasis drugs often includes functional assays that examine cancer cell invasion inside a three-dimensional hydrogel that mimics the extracellular matrix (ECM). Here, we built a mechanically tuneable collagen hydrogel model to recapitulate cancer spreading into heterogeneous tumour stroma and monitored the three-dimensional invasion of highly malignant breast cancer cells, MDA-MB-231. Migration assays were carried out in the presence and the absence of drugs affecting four typical molecular mechanisms involved in cell migration, as well as under five ECMs with different biophysical properties. Strikingly, the effects of the drugs were observed to vary strongly with matrix mechanics and microarchitecture, despite the little dependence of the inherent cancer cell migration on the ECM condition. Specifically, cytoskeletal contractility-targeting drugs reduced migration speed in sparse gels, whereas migration in dense gels was retarded effectively by inhibiting proteolysis. The results corroborate the ability of cancer cells to switch their multiple invasion mechanisms depending on ECM condition, thus suggesting the importance of factoring in the biophysical properties of the ECM in anti-metastasis drug screenings.

Association of TGFBR2 rs6785358 Polymorphism with Increased Risk of Congenital Ventricular Septal Defect in a Chinese Population

Transforming growth factor beta receptor 2 (TGFBR2) plays a central role in normal heart development, and we investigated whether TGFBR2 polymorphism confers the risk of congenital ventricular septal defect (CVSD). The case-control study included 115 CVSD children and 188 healthy children in a Chinese population. TGFBR2 rs6785358 polymorphism was genotyped with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Enzyme-linked immunoassay (ELISA) was used to detect serum TGFBR2 levels. The genotype and allele frequency of TGFBR2 rs6785358 were significantly higher in the CVSD group than in the controls (all P < 0.05). The G allele carriers were associated with increased CVSD risk compared with the A allele carriers in CVSD group (OR 3.503, 95 % CI 2.670-4.596). Stratified analysis by gender revealed that the TGFBR2 rs6785358 genotype and allele frequency were significantly different between the CVSD case and controls, in both the male subgroup and the female subgroup (all P < 0.001). The G allele carriers were more susceptible to CVSD risk than the A allele carriers in both the male subgroup (OR 9.096, 95 % CI 5.398-15.33) and the female subgroup (OR 3.148, 95 % CI 1.764-5.618). Logistic regression analysis revealed that age, gender and genotype were associated with the risk of CVSD (all P < 0.05). The study findings revealed that TGFBR2 rs6785358 polymorphism contributes to CVSD susceptibility, and the G allele may increase the risk of CVSD.

Generation of cardiac progenitor cells through epicardial to mesenchymal transition

The epithelial to mesenchymal transition (EMT) is a biological process that drives the formation of cells involved both in tissue repair and in pathological conditions, including tissue fibrosis and tumor metastasis by providing cancer cells with stem cell properties. Recent findings suggest that EMT is reactivated in the heart following ischemic injury. Specifically, epicardial EMT might be involved in the formation of cardiac progenitor cells (CPCs) that can differentiate into endothelial cells, smooth muscle cells, and, possibly, cardiomyocytes. The identification of mechanisms and signaling pathways governing EMT-derived CPC generation and differentiation may contribute to the development of a more efficient regenerative approach for adult heart repair. Here, we summarize key literature in the field.

Epithelial cell polarity determinant CRB3 in cancer development

Cell polarity, which is defined as asymmetry in cell shape, organelle distribution and cell function, is essential in numerous biological processes, including cell growth, cell migration and invasion, molecular transport, and cell fate. Epithelial cell polarity is mainly regulated by three conserved polarity protein complexes, the Crumbs (CRB) complex, partitioning defective (PAR) complex and Scribble (SCRIB) complex. Research evidence has indicated that dysregulation of cell polarity proteins may play an important role in cancer development. Crumbs homolog 3 (CRB3), a member of the CRB complex, may act as a cancer suppressor in mouse kidney epithelium and mouse mammary epithelium. In this review, we focus on the current data available on the roles of CRB3 in cancer development.

Relationship between resistance of colon cancer cells to doxorubicin and epithelial-mesenchymal transition

AIM: To evaluate whether resistance of colon cancer cells to doxorubicin is related with the epithelial-mesenchymal transition (EMT) in vitro.

METHODS: Different concentrations of doxorubicin were used in colon cancer HCT116 cells for 24 h to determine the optimal concentration of doxorubicin, and then 50 nmol/L of doxorubicin was applied to treat colon cancer HCT116 cells for 7 d. Cell viability was determined by MTT assay, and the protein expression of multidrug resistance gene encoded plasma membrane glycoprotein (MDR p-gp), EMT related markers E-cadherin, Vimentin, and related transcription factors Snail and Slug was detected by Western blot. Snail and Slug expression was verified by immunofluorescence staining.

RESULTS: Doxorubicin treatment for 24 h decreased cell viability in a concentration dependent manner. MTT assay suggested that the viability of cells treated with doxorubicin (50 nmol/L) decreased from the first to third day, but gradually increased from the fourth day. Western blot results indicated that doxorubicin significantly enhanced the expression of MDR p-gp, Vimentin, Snail and Slug and decreased the expression of E-cadherin compared with the control group. Immunofluorescence staining also revealed that Snail and Slug expression was significantly higher than that in the control cells.

CONCLUSION: Resistance of HCT116 cells to doxorubicin might be related with EMT.

Pulmonary endoderm, second heart field and the morphogenesis of distal outflow tract in mouse embryonic heart

The second heart field (SHF), foregut endoderm and sonic hedgehog (SHH) signaling pathway are all reported to associate with normal morphogenesis and septation of outflow tract (OFT). However, the morphological relationships of the development of foregut endoderm and expression of SHH signaling pathway members with the development of surrounding SHF and OFT are seldom described. In this study, serial sections of mouse embryos from ED9 to ED13 (midgestation) were stained with a series of marker antibodies for specifically highlighting SHF (Isl-1), endoderm (Foxa2), basement membrane (Laminin), myocardium (MHC) and smooth muscle (α-SMA) respectively, or SHH receptors antibodies including patched1 (Ptc1), patched2 (Ptc2) and smoothened, to observe the spatiotemporal relationship between them and their contributions to OFT morphogenesis. Our results demonstrated that the development of an Isl-1 positive field in the splanchnic mesoderm ventral to foregut, a subset of SHF, is closely coupled with pulmonary endoderm or tracheal groove, the Isl-1 positive cells surrounding pulmonary endoderm are distributed in a special cone-shaped pattern and take part in the formation of the lateral walls of the intrapericardial aorta and pulmonary trunk and the transient aortic-pulmonary septum, and Ptc1 and Ptc2 are exclusively expressed in pulmonary endoderm during this Isl-l positive field development, suggesting special roles played in inducing the Isl-l positive field formation by pulmonary endoderm. It is indicated that pulmonary endoderm plays a role in the development and specification of SHF in midgestation, and that pulmonary endoderm-associated Isl-l positive field is involved in patterning the morphogenesis and septation of the intrapericardial arterial trunks.

An EMT spectrum defines an anoikis-resistant and spheroidogenic intermediate mesenchymal state that is sensitive to e-cadherin restoration by a src-kinase inhibitor, saracatinib (AZD0530)

The phenotypic transformation of well-differentiated epithelial carcinoma into a mesenchymal-like state provides cancer cells with the ability to disseminate locally and to metastasise. Different degrees of epithelial-mesenchymal transition (EMT) have been found to occur in carcinomas from breast, colon and ovarian carcinoma (OC), among others. Numerous studies have focused on bona fide epithelial and mesenchymal states but rarely on intermediate states. In this study, we describe a model system for appraising the spectrum of EMT using 43 well-characterised OC cell lines. Phenotypic EMT characterisation reveals four subgroups: Epithelial, Intermediate E, Intermediate M and Mesenchymal, which represent different epithelial-mesenchymal compositions along the EMT spectrum. In cell-based EMT-related functional studies, OC cells harbouring an Intermediate M phenotype are characterised by high N-cadherin and ZEB1 expression and low E-cadherin and ERBB3/HER3 expression and are more anoikis-resistant and spheroidogenic. A specific Src-kinase inhibitor, Saracatinib (AZD0530), restores E-cadherin expression in Intermediate M cells in in vitro and in vivo models and abrogates spheroidogenesis. We show how a 33-gene EMT Signature can sub-classify an OC cohort into four EMT States correlating with progression-free survival (PFS). We conclude that the characterisation of intermediate EMT states provides a new approach to better define EMT. The concept of the EMT Spectrum allows the utilisation of EMT genes as predictive markers and the design and application of therapeutic targets for reversing EMT in a selective subgroup of patients.

Screening therapeutic EMT blocking agents in a three-dimensional microenvironment

Epithelial-mesenchymal transition (EMT) plays a critical role in the early stages of dissemination of carcinoma leading to metastatic tumors, which are responsible for over 90% of all cancer-related deaths. Current therapeutic regimens, however, have been ineffective in the cure of metastatic cancer, thus an urgent need exists to revisit existing protocols and to improve the efficacy of newly developed therapeutics. Strategies based on preventing EMT could potentially contribute to improving the outcome of advanced stage cancers. To achieve this goal new assays are needed to identify targeted drugs capable of interfering with EMT or to revert the mesenchymal-like phenotype of carcinoma to an epithelial-like state. Current assays are limited to examining the dispersion of carcinoma cells in isolation in conventional 2-dimensional (2D) microwell systems, an approach that fails to account for the 3-dimensional (3D) environment of the tumor or the essential interactions that occur with other nearby cell types in the tumor microenvironment. Here we present a microfluidic system that integrates tumor cell spheroids in a 3D hydrogel scaffold, in close co-culture with an endothelial monolayer. Drug candidates inhibiting receptor activation or signal transduction pathways implicated in EMT have been tested using dispersion of A549 lung adenocarcinoma cell spheroids as a metric of effectiveness. We demonstrate significant differences in response to drugs between 2D and 3D, and between monoculture and co-culture.

The invasion inhibitor sarasinoside A1 reverses mesenchymal tumor transformation in an E-cadherin-independent manner

During metastatic progression, an aberrant epithelial-to-mesenchymal transformation (EMT) that is most often driven by the loss of the cell-cell adhesion molecule E-cadherin generates noncohesive tumor cells that are highly invasive. We used mesenchymally transformed, E-cadherin-negative MDA-MB-231 breast carcinoma cells in a natural product screen and determined that the triterpenoid saponin sarasinoside A1 inhibited their invasion and the invasion of a number of other tumor cell lines. Sarasinoside A1 also caused MDA-MB-231 cells to become cohesive in a three-dimensional basement membrane and collagen gel cultures. In two-dimensional culture, sarasinoside A1 initiated a morphologic re-epithelialization of MDA-MB-231 cells wherein preexisting nonepithelial cadherins and the junction-associated proteins β-catenin and ZO-1 all relocalized to sites of cell-cell contact. In addition, the intercellular space between neighboring cells narrowed considerably, the stability of polymerized actin at cell-cell contact sites increased, and there was a recruitment and stabilization of nectin-based adhesion complexes to these sites, all of which strongly suggested that functional cell-cell junctions had formed. Importantly, sarasinoside A1 induced nascent cell-cell junction formation that did not require changes in gene expression and was not associated with an induction of E-cadherin but resulted in increased activation of Rap GTPases. Therefore, our findings with sarasinoside A1 suggest that it may be possible to re-epithelialize metastatic tumor cells with phenotypic consequence even when E-cadherin is completely absent.

Suppression of HER-2 via siRNA interference promotes apoptosis and decreases metastatic potential of SKOV‑3 human ovarian carcinoma cells

The aberrant expression of human epidermal growth factor receptor-2 (HER-2) has been detected in ovarian cancer. However, the role of HER-2 in the development of ovarian cancer has not been sufficiently elucidated. The objective of this study was to determine the role of HER-2 in the apoptosis and metastasis of SKOV-3 ovarian cancer cells. SKOV-3 cells were transfected with three double‑stranded small interfering RNA (siRNA) molecules that target HER-2. Various sequences were synthesized by T7 transcription in vitro to select the most effective HER-2‑silencing siRNA. SKOV-3 cells were examined for growth inhibition using the MTT proliferation assay and apoptosis was assessed using flow cytometry and TUNEL assay. The Matrigel basement memebrane matrix was used to assess invasion and chemotactic mobility, as a model of tumor cell metastasis. Western blot analysis was used to detect the expression of matrix metallopeptidase-9 (MMP-9), E-cadherin, N-cadherin and vimentin. siRNA interference in HER-2 resulted in decreased cell proliferation and invasion and increased apoptosis. Western blot analysis demonstrated a marked increase in E-cadherin and MMP-9 and a reduction in N-cadherin and vimentin protein levels in the SKOV-3 cells. The suppression of HER-2 expression resulted in apoptosis and the inhibition of metastasis of SKOV-3 cells. Therefore, the overexpression of the HER-2 gene can enhance the metastatic potential of SKOV-3 cells by increasing the protein levels of MMP-9. Epithelial-mesenchymal transition may be involved in the HER-2 siRNA-induced invasion and migration of SKOV-3 cells. Taken together, these results suggest that HER-2 functions as an oncogene and may thus be an attractive therapeutic target in SKOV-3 ovarian cancer cells.

Epithelial-mesenchymal transitions: insights from development

Epithelial-mesenchymal transition (EMT) is a crucial, evolutionarily conserved process that occurs during development and is essential for shaping embryos. Also implicated in cancer, this morphological transition is executed through multiple mechanisms in different contexts, and studies suggest that the molecular programs governing EMT, albeit still enigmatic, are embedded within developmental programs that regulate specification and differentiation. As we review here, knowledge garnered from studies of EMT during gastrulation, neural crest delamination and heart formation have furthered our understanding of tumor progression and metastasis.

Endocardial and epicardial epithelial to mesenchymal transitions in heart development and disease

Epithelial to mesenchymal transition (EMT) converts epithelial cells to mobile and developmentally plastic mesenchymal cells. All cells in the heart arise from one or more EMTs. Endocardial and epicardial EMTs produce most of the noncardiomyocyte lineages of the mature heart. Endocardial EMT generates valve progenitor cells and is necessary for formation of the cardiac valves and for complete cardiac septation. Epicardial EMT is required for myocardial growth and coronary vessel formation, and it generates cardiac fibroblasts, vascular smooth muscle cells, a subset of coronary endothelial cells, and possibly a subset of cardiomyocytes. Emerging studies suggest that these developmental mechanisms are redeployed in adult heart valve disease, in cardiac fibrosis, and in myocardial responses to ischemic injury. Redirection and amplification of disease-related EMTs offer potential new therapeutic strategies and approaches for treatment of heart disease. Here, we review the role and molecular regulation of endocardial and epicardial EMT in fetal heart development, and we summarize key literature implicating reactivation of endocardial and epicardial EMT in adult heart disease.

TGFβ-dependent epithelial-to-mesenchymal transition is required to generate cardiospheres from human adult heart biopsies

Autologous cardiac progenitor cells (CPCs) isolated as cardiospheres (CSps) represent a promising candidate for cardiac regenerative therapy. A better understanding of the origin and mechanisms underlying human CSps formation and maturation is undoubtedly required to enhance their cardiomyogenic potential. Epithelial-to-mesenchymal transition (EMT) is a key morphogenetic process that is implicated in the acquisition of stem cell-like properties in different adult tissues, and it is activated in the epicardium after ischemic injury to the heart. We investigated whether EMT is involved in the formation and differentiation of human CSps, revealing that an up-regulation of the expression of EMT-related genes accompanies CSps formation that is relative to primary explant-derived cells and CSp-derived cells grown in a monolayer. EMT and CSps formation is enhanced in the presence of transforming growth factor β1 (TGFβ1) and drastically blocked by the type I TGFβ-receptor inhibitor SB431452, indicating that TGFβ-dependent EMT is essential for the formation of these niche-like 3D-multicellular clusters. Since TGFβ is activated in the myocardium in response to injury, our data suggest that CSps formation mimics an adaptive mechanism that could potentially be enhanced to increase in vivo or ex vivo regenerative potential of adult CPCs.

Epithelial plasticity, cancer stem cells, and the tumor-supportive stroma in bladder carcinoma

High recurrence rates and poor survival rates of metastatic bladder cancer emphasize the need for a drug that can prevent and/or treat bladder cancer progression and metastasis formation. Accumulating evidence suggests that cancer stem/progenitor cells are involved in tumor relapse and therapy resistance in urothelial carcinoma. These cells seem less affected by the antiproliferative therapies, as they are largely quiescent, have an increased DNA damage response, reside in difficult-to-reach, protective cancer stem cell niches and express ABC transporters that can efflux drugs from the cells. Recent studies have shown that epithelial-to-mesenchymal transition (EMT), a process in which sessile, epithelial cells switch to a motile, mesenchymal phenotype may render cancer cells with cancer stem cells properties and/or stimulate the expansion of this malignant cellular subpopulation. As cancer cells undergo EMT, invasiveness, drug resistance, angiogenesis, and metastatic ability seem to increase in parallel, thus giving rise to a more aggressive tumor type. Furthermore, the tumor microenvironment (tumor-associated stromal cells, extracellular matrix) plays a key role in tumorigenesis, tumor progression, and metastasis formation. Taken together, the secret for more effective cancer therapies might lie in developing and combining therapeutic strategies that also target cancer stem/progenitor cells and create an inhospitable microenvironment for highly malignant bladder cancer cells. This review will focus on the current concepts about the role of cancer stem cells, epithelial plasticity, and the supportive stroma in bladder carcinoma. The potential implications for the development of novel bladder cancer therapy will be discussed.

The epithelial-mesenchymal transition under control: global programs to regulate epithelial plasticity

The epithelial to mesenchymal transition or EMT has become one of the most exciting fields in cancer research. Nevertheless, its relevance in tumor biology and the metastatic process still faces some controversy. Clarification may arise when considering the EMT as a reversible and often incomplete process, essentially a manifestation of strong epithelial plasticity. Transient cellular states are generated to fulfill specific requirements in each and all the steps of the metastatic process, from primary tumor cell detachment to dissemination and colonization. Opposing multiple cellular programs that promote or prevent EMT, thereby destabilizing or reinforcing epithelial integrity, play a central role in the inherent cellular dynamics of cancer progression. These cell biology programs not only drive cells towards the epithelial or the mesenchymal state but also impinge into multiple cellular and global responses including proliferation, stemness, chemo and immunotherapy resistance, inflammation and immunity, all relevant for the development of the metastatic disease.

A cell-based small molecule screening method for identifying inhibitors of epithelial-mesenchymal transition in carcinoma

Epithelial Mesenchymal Transition (EMT) is a crucial mechanism for carcinoma progression, as it provides routes for in situ carcinoma cells to dissociate and become motile, leading to localized invasion and metastatic spread. Targeting EMT therefore represents an important therapeutic strategy for cancer treatment. The discovery of oncogene addiction in sustaining tumor growth has led to the rapid development of targeted therapeutics. Whilst initially optimized as anti-proliferative agents, it is likely that some of these compounds may inhibit EMT initiation or sustenance, since EMT is also modulated by similar signaling pathways that these compounds were designed to target. We have developed a novel screening assay that can lead to the identification of compounds that can inhibit EMT initiated by growth factor signaling. This assay is designed as a high-content screening assay where both cell growth and cell migration can be analyzed simultaneously via time-course imaging in multi-well plates. Using this assay, we have validated several compounds as viable EMT inhibitors. In particular, we have identified compounds targeting ALK5, MEK, and SRC as potent inhibitors that can interfere with EGF, HGF, and IGF-1 induced EMT signaling. Overall, this EMT screening method provides a foundation for improving the therapeutic value of recently developed compounds in advanced stage carcinoma.