Snail-associated epithelial–mesenchymal transition promotes oesophageal squamous cell carcinoma motility and progression

Morphological Changes Induced by TKS4 Deficiency Can Be Reversed by EZH2 Inhibition in Colorectal Carcinoma Cells

BACKGROUND

The scaffold protein tyrosine kinase substrate 4 (TKS4) undergoes tyrosine phosphorylation by the epidermal growth factor receptor (EGFR) pathway via Src kinase. The TKS4 deficiency in humans is responsible for the manifestation of a genetic disorder known as Frank-Ter Haar syndrome (FTHS). Based on our earlier investigation, the absence of TKS4 triggers migration, invasion, and epithelial-mesenchymal transition (EMT)-like phenomena while concurrently suppressing cell proliferation in HCT116 colorectal carcinoma cells. This indicates that TKS4 may play a unique role in the progression of cancer. In this study, we demonstrated that the enhancer of zeste homolog 2 (EZH2) and the histone methyltransferase of polycomb repressive complex 2 (PRC2) are involved in the migration, invasion, and EMT-like changes in TKS4-deficient cells (KO). EZH2 is responsible for the maintenance of the trimethylated lysine 27 on histone H3 (H3K27me3).

METHODS

We performed transcriptome sequencing, chromatin immunoprecipitation, protein and RNA quantitative studies, cell mobility, invasion, and proliferation studies combined with/without the EZH2 activity inhibitor 3-deazanoplanocine (DZNep).

RESULTS

We detected an elevation of global H3K27me3 levels in the TKS4 KO cells, which could be reduced with treatment with DZNep, an EZH2 inhibitor. Inhibition of EZH2 activity reversed the phenotypic effects of the knockout of TKS4, reducing the migration speed and wound healing capacity of the cells as well as decreasing the invasion capacity, while the decrease in cell proliferation became stronger. In addition, inhibition of EZH2 activity also reversed most epithelial and mesenchymal markers. We investigated the wider impact of TKS4 deletion on the gene expression profile of colorectal cancer cells using transcriptome sequencing of wild-type and TKS4 knockout cells, particularly before and after treatment with DZNep. Additionally, we observed changes in the expression of several protein-coding genes and long non-coding RNAs that showed a recovery in expression levels following EZH2 inhibition.

CONCLUSIONS

Our results indicate that the removal of TKS4 causes a notable disruption in the gene expression pattern, leading to the disruption of several signal transduction pathways. Inhibiting the activity of EZH2 can restore most of these transcriptomics and phenotypic effects in colorectal carcinoma cells.

Pyruvate Kinase Differentially Alters Metabolic Signatures during Head and Neck Carcinogenesis

During glycolysis, the muscle isoform of pyruvate kinase PKM2 produces ATP in exchange for dephosphorylation of phosphoenolpyruvate (PEP) into pyruvate. PKM2 has been considered as a tumor-promoting factor in most cancers, whereas the regulatory role of PKM2 during head and neck carcinogenesis remained to be delineated. PKM2 mRNA and protein expression was examined in head and neck tumorous specimens. The role of PKM2 in controlling cellular malignancy was determined in shRNA-mediated PKM2-deficient head and neck squamous cell carcinoma (HNSC) cells. In agreement with the results in other cancers, PKM2 expression is enriched in both mouse and human HNSC tissues. Nevertheless, PKM2 mRNA expression reversely correlated with tumor stage, and greater recurrence-free survival rates are evident in the PKM2high HNSC population, arguing that PKM2 may be tumor-suppressive. Multifaceted analyses showed a greater in vivo xenografic tumor growth and an enhanced cisplatin resistance in response to PKM2 loss, whereas PKM2 silencing led to reduced cell motility. At the molecular level, metabolic shifts towards mitochondrial metabolism and activation of oncogenic Protein kinase B (PKB/Akt) and extracellular signal-regulated kinase (ERK) signals were detected in PKM2-silencing HNSC cells. In sum, our findings demonstrated that PKM2 differentially modulated head and neck tumorigenicity via metabolic reprogramming.

Expression of Snail and Twist compared with clinical and pathological parameters in patients with gastric cancer

INTRODUCTION

Epithelial-mesenchymal transition (EMT) is a process of change in the cellular phenotype from epithelial to mesenchymal morphology. The changes at the cellular level can explain the great heterogeneity and plasticity in the different histological subtypes of gastric carcinomas, which causes difficulties in therapy. In it, epithelial cells reduce intercellular adhesion, which is crucial in the process of invasion and metastasis of gastric carcinomas. Inhibition of cell adhesion molecules such as E-cadherin is known to be influenced by a number of transcription factors, such as Snail and Twist.

Epithelial–Mesenchymal Transition of Breast Cancer Cells Induced by Activation of the Transcription Factor Snail1

Cancer cells use the program of epithelial-mesenchymal transition (EMT) for initiation of the invasion-metastasis cascade. Using confocal and video-microscopy, reorganization of the cytoskeleton was studied in the MCF-7 breast cancer cells undergoing Snail1-induced EMT. We used the line of MCF-7 cells stably expressing tetOff SNAI1 construct (MCF-7-SNAI1 cells). After tetracycline washout and Snail1 activation MCF-7-SNAI1 cells underwent EMT and acquired a migratory phenotype while retaining expression of E-cadherin. We identified five variants of the mesenchymal phenotype, differing in cell morphology and migration velocity. Migrating cells had high degree of plasticity, which allowed them to quickly change both the phenotype and migration velocity. The changes of the phenotype of MCF-7-SNAI1 cells are based on the Arp2/3-mediated branched actin network polymerization in lamellipodia, myosin-based contractility in the zone behind the nucleus, redistribution of adhesive proteins from cell-cell contacts to the leading edge, and reorganization of intermediate keratin filaments.

Claudins: The Newly Emerging Targets in Breast Cancer

Claudin-low breast cancers are recently described entities showing low expression of certain claudins and cell adhesion molecules. Claudins constitute the backbone of tight junctions (TJs) formed between 2 cells. Their dysregulation plays a vital role in tumorigenesis. First part of the article focuses on the role of claudins in the TJ organization, their structural-functional characteristics, and post-transcriptional and translational modifications. The latter part of the review attempts to summarize existing knowledge regarding the status of claudins in breast cancer. The article also provides an overview of the effect of claudins on tumor progression, metastasis, stemness, chemotherapy resistance, and their crosstalk with relevant signaling pathways in breast cancer. Claudins can act as 2-edged swords in tumors. Some claudins have either tumor-suppressive/ promoting action, while others work as both in a context-dependent manner. Claudins regulate many important events in breast cancer. However, the intricacies involved in their activity are poorly understood. Post-translational modifications in claudins and their impact on TJ integrity, function, and tumor behavior are still unclear. Although their role in adverse events in breast cancer is recognized, their potential to serve as relevant targets for future therapeutics, especially for difficult-to-treat subtypes of the above malignancy, remains to be explored.

Role of Cell-Cell Junctions in Oesophageal Squamous Cell Carcinoma

Cell-cell junctions comprise various structures, including adherens junctions, tight junctions, desmosomes, and gap junctions. They link cells to each other in tissues and regulate tissue homeostasis in critical cellular processes. Recent advances in cell-cell junction research have led to critical discoveries. Cell-cell adhesion components are important for the invasion and metastasis of tumour cells, which are not only related to cell-cell adhesion changes, but they are also involved in critical molecular signal pathways. They are of great significance, especially given that relevant molecular mechanisms are being discovered, there are an increasing number of emerging biomarkers, targeted therapies are becoming a future therapeutic concern, and there is an increased number of therapeutic agents undergoing clinical trials. Oesophageal squamous cell carcinoma (ESCC), the most common histological subtype of oesophageal cancer, is one of the most common cancers to affect epithelial tissue. ESCC progression is accompanied by the abnormal expression or localisation of components at cell-cell junctions. This review will discuss the recent scientific developments related to the molecules at cell-cell junctions and their role in ESCC to offer valuable insights for readers, provide a global view of the relationships between position, construction, and function, and give a reference for future mechanistic studies, diagnoses, and therapeutic developments.

HuR Affects the Radiosensitivity of Esophageal Cancer by Regulating the EMT-Related Protein Snail

Purpose

We previously found that Hu antigen R (HuR) can regulate the proliferation and metastasis of esophageal cancer cells. This study aims to explore the effects of HuR on the radiosensitivity of esophageal cancer.

Materials and Method

Analyses of CCK-8, colony formation assay, Western blot, immunofluorescence, flow cytometry, reactive oxygen species (ROS), and mitochondrial membrane potential were conducted to characterize the esophageal cancer cells. Nude mouse models were used to detect the effects of HuR in a combination of X-ray treatment on the subcutaneous xenografts of esophageal cancer. In addition, a luciferase assay was used to detect the direct interaction of HuR with Snail mRNA 3’-UTR.

Results

The down-regulation of HuR combined with X-ray can significantly inhibit the proliferation and colony formation of esophageal cancer cells. Flow cytometry data showed that the down-regulation of HuR could induce a G1 phase cell cycle block in esophageal cancer cells, and aggravate X-ray-induced apoptosis, indicated by the increases of apoptosis-related proteins Bax, caspase-3 and caspase-9. Moreover, the down-regulation of HuR could significantly impair the mitochondrial membrane potential and increase the ROS production and DNA double-strand break marker γH2AX expression in esophageal cancer cells that were exposed to X-rays. In vivo data showed that the down-regulation of HuR combined with radiation significantly decreased the growth of subcutaneous xenograft tumors. Furthermore, HuR could interact with Snail. Up-regulation of Snail can reverse the EMT inhibitory effects caused by HuR down-regulation, and attenuate the tumor-inhibiting and radiosensitizing effects caused by HuR down-regulation.

Conclusion

In summary, our data demonstrate that HuR effectively regulates the radiosensitivity of esophageal cancer, which may be achieved by stabilizing Snail. Thus, HuR/Snail axis is a potentially therapeutic target for the treatment of esophageal cancer.

Immunohistochemical expression of Snail1 protein in colorectal adenocarcinoma samples and its prognostic activity in Caucasian patients

Introduction

The current study investigated the expression of Snail1 protein in colon adenocarcinoma samples to assess its prognostic significance by correlating its expression with the clinicopathological variables and survival of Caucasian patients.

Aim

To investigate the clinicopathological and prognostic roles of Snail1 expression, the immunohistochemical analysis was performed in colon tumour tissues and adjacent non- pathological mucosa.

Material and methods

It should be noted that only trace expression of this protein was revealed in adjacent non-tumour colorectal mucosa, whereas the high expression was demonstrated in well differentiated, moderately differentiated, and poorly differentiated tumours.

Results

The Kaplan-Meier survival analysis showed that the overall survival rate in the group of patients with a low expression level of Snail1 was significantly longer than that for patients with a moderate or strong level of Snail1 immunoreactivity (p < 0.001). The 5-year overall survival for patients with a low, moderate, or strong level of Snail1 immunoexpression was 100%, 25.7%, and 2%, respectively. The Snail1-moderate patients had an average survival time of 44.886 months (95% CI: 40.855–48.916), whereas the Snail1-strong expression groups had an average survival time of 21.706 (95% CI: 17.863–25.549). The statistical analysis revealed that the level of the Snail1 immunohistochemical reactivity was correlated with the grade of the histological differentiation. A multivariate analysis demonstrated that the grade of tumour differentiation (HR = 2.150; 95% CI: 1.380–3.349, p = 0.001) and Snail1 expression (HR = 3.901; 95% CI: 2.436–6.247, p < 0.001) were the independent risk factors for worse survival.

Conclusions

In colon adenocarcinoma patients, the expression of Snail1 may act as the independent risk factors for worse survival.

Melatonin and hyperbaric oxygen therapies suppress colorectal carcinogenesis through pleiotropic effects and multifaceted mechanisms

Colorectal cancer (CRC) is the third most common cancer worldwide. Colorectal carcinogenesis is frequently induced by hypoxia to trigger the reprogramming of cellular metabolism and gain of malignant phenotypes. Previously, hyperbaric oxygen (HBO) therapy and melatonin have been reported to alter the hypoxic microenvironment, resulting in inhibiting cancer cell survival. Accordingly, this study tested the hypothesis whether HBO and melatonin effectively inhibited CRC carcinogenesis. In vitro results indicated that melatonin therapy significantly suppressed the malignant phenotypes, including colony formation, growth, invasion, migration and cancer stemness with dose-dependent manners in CRC cell lines through multifaceted mechanisms. Similar to in vitro study, in vivo findings further demonstrated the melatonin, HBO and combined treatments effectively promoted apoptosis (cleaved-caspase 3/ cleaved-PARP) and arrested tumor proliferation, followed by inhibiting colorectal tumorigenesis in CRC xenograft tumor model. Moreover, melatonin, HBO and combined treatments modulated multifaceted mechanisms, including decreasing HIF-1α expression, alleviating AKT activation, repressing glycolytic metabolism (HK-2/PFK1/PKM2/LDH), restraining cancer stemness pathway (TGF-β/p-Smad3/Oct4/Nanog), reducing inflammation (p-NFκB/ COX-2), diminishing immune escape (PD-L1), and reversing expression of epithelial mesenchymal transition (E-cadherin/N-cadherin/MMP9). In conclusion, melatonin and HBO therapies suppressed colorectal carcinogenesis through the pleiotropic effects and multifaceted mechanisms, suggesting melatonin and HBO treatments could be novel therapeutic strategies for CRC treatment.

Expression of 34βE12 may be an independent predictor of survival in breast cancer

Objectives

To investigate the relationship between high-molecular-weight cytokeratin (34βE12) and clinicopathological parameters (including HER-2, Ki67 and steroid receptors) in breast cancer to determine its usefulness as a prognostic marker.

Methods

In this retrospective study, the expression level 34βE12 was assessed in surgically resected breast cancer specimens by immunohistochemical staining. Data were correlated with the patients’ clinicopathological parameters.

Results

Of the 348 breast cancer tissue samples, 232 (67%) showed positive expression of 34βE12. There were statistically significant differences between the positive and negative 34βE12 expression groups in tumour size, lymph node involvement, oestrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor-2 (HER2) status. There were no differences between groups in age, tumour grade, or Ki67 status. In addition, patients who were positive for 34βE12 had significantly extended overall survival. In multivariate analysis, the expression level of 34βE12 was found to be a significant independent prognostic factor.

Conclusion

These results suggest that positive 34βE12 expression is associated with a favourable outcome in breast cancer and so may be a useful prognostic factor. Further studies are required to confirm these results.

The Underappreciated Role of Epithelial Mesenchymal Transition in Chronic Obstructive Pulmonary Disease and Its Strong Link to Lung Cancer

The World Health Organisation reported COPD to be the third leading cause of death globally in 2019, and in 2020, the most common cause of cancer death was lung cancer; when these linked conditions are added together they come near the top of the leading causes of mortality. The cell-biological program termed epithelial-to-mesenchymal transition (EMT) plays an important role in organ development, fibrosis and cancer progression. Over the past decade there has emerged a substantial literature that also links EMT specifically to the pathophysiology of chronic obstructive pulmonary disease (COPD) as primarily an airway fibrosis disease; COPD is a recognised strong independent risk factor for the development of lung cancer, over and above the risks associated with smoking. In this review, our primary focus is to highlight these linkages and alert both the COPD and lung cancer fields to these complex interactions. We emphasise the need for inter-disciplinary attention and research focused on the likely crucial roles of EMT (and potential for its inhibition) with recognition of its strategic place mechanistically in both COPD and lung cancer. As part of this we discuss the future potential directions for novel therapeutic opportunities, including evidence-based strategic repurposing of currently used familiar/approved medications.

Role of ARID1A in the Regulation of Human Trophoblast Migration and Invasion

Migration and invasion of trophoblasts is critical for human placental development, trophoblastic differentiation, and pregnancy-associated diseases. AT-rich interactive domain-containing protein 1A (ARID1A), a subunit of the SWI-SNF complex, has been suggested to participate in the regulation of fertility via placental disruption in mice. However, whether ARID1A regulates human placental development and function remains unknown. Here, using human trophoblast-like JEG-3 cell line, we report that ARID1A controls trophoblast cell migration and invasion. Overexpression of ARID1A inhibits JEG-3 cell migration and invasion, whereas knockdown of ARID1A promotes migration and invasion in JEG-3 cells. Mechanistically, while ARID1A reduces JEG-3 cell migration by down-regulation of Snail transcription, it restrains JEG-3 cell invasion by binding to and destabilization of MMP-9 protein. Finally, ARID1A is apparently up-regulated in placental tissues of preeclampsia compared to that of normal pregnancies. Our results thereby imply that ARID1A acts as a critical gene in supporting the physiological function of human mature placenta.

Partial EMT in Squamous Cell Carcinoma: A Snapshot

In the process of cancer EMT, some subgroups of cancer cells simultaneously exhibit both mesenchymal and epithelial characteristics, a phenomenon termed partial EMT (pEMT). pEMT is a plastic state in which cells coexpress epithelial and mesenchymal markers. In squamous cell carcinoma (SCC), pEMT is regulated, and the phenotype is maintained via the HIPPO pathway, NOTCH pathway and TGF-β pathways and by microRNAs, lncRNAs and the cancer microenvironment (CME); thus, SCC exhibits aggressive tumorigenic properties and high stemness, which leads collective migration and therapy resistance. Few studies have reported therapeutic interventions to address cells that have undergone pEMT, and this approach may be an effective way to inhibit the plasticity, drug resistance and metastatic potential of SCC.

Downregulation of ARMC8 promotes tumorigenesis through activating Wnt/β-catenin pathway and EMT in cutaneous squamous cell carcinomas

BACKGROUND

Aberrant expression of Armadillo repeat containing 8 (ARMC8) plays crucial roles in tumor growth and metastasis of various cancers. The specific role of ARMC8 in cutaneous squamous cell carcinoma (cSCC) is yet to be elucidated.

OBJECTIVE

The present study aimed to investigate the molecular mechanisms of ARMC8 and epithelial-mesenchymal transition (EMT) in cSCC development and provide translational insights for future therapeutics.

METHODS

cSCC tumor specimens were used to determine the ARMC8 by immunohistochemistry. Three cSCC cell lines including HSC-1, HSC-5 and A431 as well as BALB/C mouse tumor model was utilized to study the potential mechanisms in tumorigenesis.

RESULTS

Our data identified ARMC8 as a direct downstream target of miR-664. We found that ARMC8 was remarkably low expression in cSCC patient specimens and cSCC cell lines. Knockdown of ARMC8 promotes tumorigenic behaviors such as increased cell proliferation, migration and invasion capacities in vitro and enhanced tumorigenicity in xenograft mouse model. Whereas ARMC8 over-expression inhibits tumorigenesis in cSCC. Together, it revealed ARMC8 functions as a tumor suppressor via restraining Wnt/β-catenin pathway and epithelial-mesenchymal transition in cSCC.

CONCLUSION

Our data verifies that aberrant expression of ARMC8 plays a vital role in carcinogenesis of cSCC. And overexpression of ARMC8 will facilitate future development of cSCC therapeutic interventions.

Targeting Galectin-1 by Aflibercept Strongly Enhances Its Antitumor Effect in Neuroendocrine Carcinomas

BACKGROUND

Galectin-1 (Gal-1) plays major roles in cancer by modulating different processes leading to tumor development and progression. In the last years, it has been suggested as a promising target for anticancer therapy. Recently, aflibercept has shown high affinity for Gal-1. Here, we investigated how aflibercept could exert its antitumor activity via Gal-1-driven pathways in neuroendocrine carcinomas (NECs).

METHODS AND RESULTS

NEC tumor xenografts were used to assess the effect of aflibercept on Gal-1 functions. Aflibercept induced a significant reduction of Gal-1 at epithelial, stromal, and extracellular localizations in lung NEC, whereas this was not observed in colon NECs, which displayed low expression of Gal-1. Additionally, aflibercept significantly reduced p-VEGFR2 protein, extracellular matrix remodeling, epithelial-mesenchymal transition, and activation of cancer-associated fibroblast hampering cell invasion in lung NEC but not in colon NEC. Gal-1 screening in human NECs confirmed that pulmonary and pancreatic tumors displayed higher levels of Gal-1 than colon NECs, becoming good candidates to benefit from aflibercept treatment.

CONCLUSIONS

The lack of validated predictive markers of aflibercept is a weakness for guaranteeing the best treatment management with this drug. This work provides new mechanistic insight of aflibercept depending on Gal-1. Thus, in tumors overexpressing Gal-1, aflibercept has not only an antiangiogenic effect but also prevents Gal-1-mediated tumor-stroma cross talk. The stronger aflibercept effect in tumors with high levels of Gal-1 points out this protein as a molecular marker to predict the efficacy of this agent not only for NECs but also for other tumors with high levels of this protein.

PURα mediates epithelial-mesenchymal transition to promote esophageal squamous cell carcinoma progression by regulating Snail2

Esophageal squamous cell carcinoma (ESCC) is one of the most common lethal cancers in the world. Dysregulation of purine-rich element binding protein alpha (PURα), which contributes to the initiation of PURΑ syndrome, is reportedly involved in the progression of multiple cancers, but its function and underlying mechanisms in ESCC progression remain unclear. Here, we first demonstrated that PURα promoted cell growth, migration and invasion in ESCC both in vitro and in vivo. An immunohistochemistry assay was then performed on 225 ESCC tissues, showing that high PURα expression was positively associated with lymph node metastasis and the AJCC stage, and the ESCC patients with positive PURα expression had worse survival. In addition, RNA sequencing implied that PURα induced epithelial-mesenchymal transition (EMT) in ESCC, which was further confirmed by qPCR, Western blotting and immunofluorescence analyses. Mechanistically, PURα enhanced the transcription of Snail2 by binding to its promoter region. Knockdown of Snail2 reversed PURα-induced EMT and inhibited the migration and invasion of ESCC cells. In conclusion, this study indicated that PURα promotes Snail2 transcriptional activity to induce EMT during ESCC progression.

Thymoquinone alleviates liver fibrosis via miR-30a-mediated epithelial-mesenchymal transition

Thymoquinone (TQ), the main active constituent of Nigella sativa seeds, has been shown to play a role in antioxidation, anti-inflammation, and antitumor. Recent studies have demonstrated that TQ contributes to the suppression of liver fibrosis. Abnormal activated epithelial-mesenchymal transition (EMT) promotes the activation of hepatic stellate cells (HSCs). However, whether the antifibrotic effects of TQ occur through inhibiting EMT is largely unknown. In this study, it was found that TQ ameliorated liver fibrosis and collagen accumulation in carbon tetrachloride (CCl4) mice. In vitro, TQ inhibited HSC activation including reduced proliferation, α-smooth muscle actin, and collagen. In addition, TQ markedly suppressed the EMT process, with enhanced E-cadherin and reduced desmin. Notably, snail family transcriptional repressor 1 (Snai1), the EMT master transcription factor, was obviously inhibited by TQ in vivo and in vitro. Further studies demonstrated that Snai1 was a target of microRNA-30a (miR-30a), which was upregulated by TQ. Interestingly, the effects of TQ on HSC activation and EMT were almost inhibited by miR-30a inhibitor. Collectively, we demonstrate that TQ inhibits HSC activation, at least in part, via regulation of miR-30a and Snai1. TQ upregulates miR-30a expression, resulting in a reduced Snai1 level as well as EMT process inactivation, which contributes to the inhibition of HSC activation. TQ may be a potential therapeutic agent for liver fibrosis.

Targeting deubiquitinating enzyme USP26 by microRNA-203 regulates Snail1's pro-metastatic functions in esophageal cancer

Background

Esophageal cancer is one of the most common cancers worldwide with poor prognosis and high mortality. The transcription factor SNAI1, encoding Snail1, is important for metastatic progression in esophageal cancer whereas the microRNA (miRNA)-203 has been shown to function as an inhibitor of metastasis in EC. The Snail1 protein is stabilized in EC partially by the deubiquitinating enzyme USP26; however, how USP26 is regulated is not completely known.

Methods

Expression of SNAI1 and USP26 messenger RNA (mRNA) and miR-203 was performed in datasets within The Cancer Genome Atlas and Gene Expression Omnibus, respectively. Expression of Snail1 and USP26 protein and miR-203 was determined in the normal esophageal cell line HET-1A and EC cell lines Kyse150 and TE-1 using western blot and quantitative polymerase chain reaction, respectively. TargetScan was used for in situ prediction of miR-203 targets and in vitro heterologous reporter assays using the wild-type and miR-203 seed mutant of the 3′ Untranslated region (UTR) of USP26 were used to investigate whether USP26 is a target of miR-203. Effects of increasing miR-203 using MIR203A/5P mimic on USP26 and Snail1 in the HET-1A, Kyse150 and TE-1 cell lines were performed using western blot and cycloheximide-based protein stability analysis. Effects of modulating miR-203 in Kyse150 and TE-1 cell lines on in vitro pro-metastatic effects were analyzed by invasion assay, scratch wound-healing assay, and chemosensitivity to 5-fluoruracil (5-FU). In vivo lung metastasis assay was used to study the effect of modulating miR-203 in Kyse150 cells.

Results

SNAI1 mRNA and HSA/MIR203 was higher and lower, respectively, in EC patients compared to tumor-adjacent normal tissues. No changes in expression of USP26 mRNA were observed in these datasets. MIR/203 expression was downregulated whereas protein expression of both Snail1 and USP26 were higher in EC cell lines Kyse150 and TE-1 compared to normal esophageal cell line HET-1A. USP26 was predicted as a potential target of miR-203 by TargetScan Release 2.0. Reporter assays confirmed USP26 as a target of miR-203 in the EC cell lines. Transfection of EC cell lines with MIR203 mimic decreased USP26 protein expression and Snail1 protein stability indicating the ability of miR-203 to regulate Snail1 protein levels via USP26. Exogenous increase in miR-203 in the EC cell lines significantly inhibited Snail-1 mediated in vitro pro-metastatic function of invasion, wound-healing, and increased chemosensitivity to 5-FU. Finally, overexpression of miR-203 inhibited in vivo lung metastasis of Kyse150 cells, which was reversed following overexpression of USP26, indicating a direct role of miR-203-mediated regulation of USP26 in metastatic progression of EC.

Conclusions

Cumulatively, these results establish an important mechanism by which decrease in miR-203 expression potentiates metastatic progression in EC via USP26-mediated stabilization of Snail1. Hence, miR-203 can serve as a biomarker of metastasis in EC and is a potential target for therapeutic intervention in EC.

Matrix metalloproteinase 2 contributes to aggressive phenotype, epithelial-mesenchymal transition and poor outcome in nasopharyngeal carcinoma

Background

Though matrix metalloproteinase 2 (MMP-2) involvement in tumor aggressiveness and invasion is well-known, its prognostic impacts still remain largely controversial. Furthermore, the correlations between MMP-2 and epithelial-mesenchymal transition (EMT) have not been directly established in nasopharyngeal carcinoma (NPC).

Materials and methods

The purpose of this study was to investigate MMP-2 expression in NPC. Tissue microarrays from 144 patients with NPC and 45 non-cancerous pharynx tissues were analyzed for MMP-2 expression by immunohistochemistry. MMP-2 expression in relation to clinicopathological characteristics and EMT were assessed in NPC. Tumor-invasive potential affected by exogenous expression of MMP-2 in NPC cells was also detected in vitro.

Results

Compared to normal nasopharyngeal epithelium, high expression of tumoral MMP-2 was detected in 47.9% of NPC samples. Significant association was found between MMP-2 expression and various aggressive features including T classification, M classification and tumor stage (P<0.05). Of note, high expression of MMP-2 was prominently observed at tumor invasive front, neoplastic spindle cells migrating into the stroma and vessel invasion. Importantly, high MMP-2 expression predicted worse survival in patients with stage III-IV (P=0.039). Overexpression of MMP-2 could decrease cell-cell adhesion, promote tumor invasion and EMT including downregulation of E-cadherin and upregulation of N-cadherin, Fibronectin and Slug of NPC cells.

Conclusion

Our findings demonstrate that MMP-2 expression contributes to tumor aggressiveness and poor prognosis, and induces the occurrence of EMT in NPC.

Association of low expression of E-cadherin and β-catenin with the progression of early stage human squamous cervical cancer

The precise involvement and mechanisms of human papilloma virus type 16 (HPV16) in epithelial-mesenchymal transition (EMT) of cervical intraepithelial neoplasia (CIN) and squamous cervical cancer (SCC) remain unknown. The present study aimed to examine the expression of EMT indicators and their association with HPV16 in CIN and early stage SCC, and their prognostic value in early stage SCC. The expression levels of E-cadherin, N-cadherin, β-catenin, vimentin, and fibronectin were determined by immunohistochemistry in 40 patients with normal uterine cervix, 22 patients with CIN1, 60 patients with CIN2-3, and 86 patients with SCC, stage Ia-IIa, according to the International Federation of Gynecology and Obstetrics. The expression of the epithelial indicators E-cadherin and β-catenin gradually declined, and the mesenchymal indicators N-cadherin, vimentin, and fibronectin increased with progression of the cervical lesions (P<0.05). Patients with SCC with lymph node metastasis, parametrial invasion, negative E-cadherin, and negative β-catenin expression had shorter overall survival (P=0.001, P=0.015, P=0.014, and P=0.043, respectively) and disease-free survival (P=0.002, P=0.021, P=0.025, and P=0.045, respectively) time. Multivariate survival analysis indicated that lymph node metastasis [Hazard ratio (HR)=3.544; P=0.010], parametrial invasion (HR=2.014; P=0.007) and E-cadherin expression (HR=0.163; P<0.001) were independently associated with overall survival, but also with disease-free survival (HR=3.612, P=0.009; HR=1.935, P=0.011; HR=0.168, P<0.001, respectively). In patients with CINs, HPV16 infection was negatively correlated with the expression of E-cadherin, and positively correlated with the expression of N-cadherin, vimentin, and fibronectin. EMT occurs during the progression of CINs to early stage SCC, and is associated with HPV16 infection in CINs. Lymph node metastasis and parametrial invasion are poor prognostic factors for SCC, while positive E-cadherin expression may serve as a protective prognostic factor for SCC.

Targeting the Overexpressed YY1 in Cancer Inhibits EMT and Metastasis

There have been recent developments in the treatment of various cancers, in particular non-metastatic cancers. However, many of the responding patients often relapse initially through the development of spread micro and macro-metastases. Unfortunately, there are very few therapeutic modalities for the treatment of metastatic cancers. The development of cancer metastasis has been proposed to involve the epithelial-mesenchymal transition (EMT), in which the tumor cells with the EMT phenotype exhibit various phenotypic markers and molecular modifications that are manifested to resist most conventional therapies. YY1 is a target of the hyperactivated nuclear factor-kappa beta pathway in cancer and it was reported that YY1 also regulates cell survival and cell proliferation in addition to its role in EMT and resistance. The overexpression of YY1 in the majority of cancers has been correlated with poor prognosis. It is hypothesized that targeting YY1 may result in several anti-tumor activities, including inhibition of cell survival and cell proliferation, inhibition of EMT, and reversal of resistance. This review discusses the potential therapeutic targeting of an overexpressed transcription factor, Yin Yang 1 (YY1), which has been implicated in the development of EMT and drug resistance. Several examples targeting YY1 in experimental models are presented.

Coexpression of FOXK1 and vimentin promotes EMT, migration, and invasion in gastric cancer cells

In human gastric cancer (GC), the upregulation of FOXK1 and vimentin is frequently observed in cancer cells and correlates with increased malignancy. We report that FOXK1 synergizes with vimentin to promote GC invasion and metastasis via the induction of epithelial-mesenchymal transition (EMT). We showed that higher expression levels of FOXK1 were significantly associated with GC development. FOXK1 can physically interact with and stabilize vimentin. Moreover, a positive correlation between the expression of FOXK1 and vimentin was found in GC cells. Higher expression levels of these two proteins were significantly associated with differentiation, lymph node metastasis, AJCC stage, and poorer prognosis. Furthermore, the coexpression of FOXK1 and vimentin enhances cell metastasis through the induction of EMT in GC cells. However, the siRNA-mediated repression of vimentin in FOXK1-overexpressing cells reversed the EMT-like phenotype and reduced GC cell migration and invasion in vitro and in vivo. Altogether, our findings suggest that the vimentin-FOXK1 axis provides new insights into the molecular mechanisms underlying EMT regulation during GC progression and metastasis.

Hybrid epithelial/mesenchymal phenotypes promote metastasis and therapy resistance across carcinomas

Cancer metastasis and therapy resistance are the major unsolved clinical challenges, and account for nearly all cancer-related deaths. Both metastasis and therapy resistance are fueled by epithelial plasticity, the reversible phenotypic transitions between epithelial and mesenchymal phenotypes, including epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET). EMT and MET have been largely considered as binary processes, where cells detach from the primary tumor as individual units with many, if not all, traits of a mesenchymal cell (EMT) and then convert back to being epithelial (MET). However, recent studies have demonstrated that cells can metastasize in ways alternative to traditional EMT paradigm; for example, they can detach as clusters, and/or occupy one or more stable hybrid epithelial/mesenchymal (E/M) phenotypes that can be the end point of a transition. Such hybrid E/M cells can integrate various epithelial and mesenchymal traits and markers, facilitating collective cell migration. Furthermore, these hybrid E/M cells may possess higher tumor-initiation and metastatic potential as compared to cells on either end of the EMT spectrum. Here, we review in silico, in vitro, in vivo and clinical evidence for the existence of one or more hybrid E/M phenotype(s) in multiple carcinomas, and discuss their implications in tumor-initiation, tumor relapse, therapy resistance, and metastasis. Together, these studies drive the emerging notion that cells in a hybrid E/M phenotype may occupy 'metastatic sweet spot' in multiple subtypes of carcinomas, and pathways linked to this (these) hybrid E/M state(s) may be relevant as prognostic biomarkers as well as a promising therapeutic targets.

Snail-1 Silencing by siRNA Inhibits Migration of TE-8 Esophageal Cancer Cells Through Downregulation of Metastasis-Related Genes

Purpose: Snail-1 is a transcription factor, which takes part in EMT, a process related to the emergence of invasion and cancer progression. The purpose of this study was to evaluate the effect of Snail-1 silencing on the human esophageal squamous cell carcinoma cell line, namely TE-8, in vitro.

Methods: In this study, transfection of Snail-1 specific siRNA was conducted into TE-8 cells. The relative mRNA expression levels of Snail-1, Vimentin, CXCR4 and MMP-9 and transcription levels of miR-34a and let-7a were investigated by quantitative Real-time PCR. Western blotting was carried out to evaluate the Snail-1 protein level. Migration assay of TE-8 cells was also performed following the presence or absence of Snail-1 specific siRNA. MTT and TUNEL assays were performed to evaluate cell viability after Snail-1 silencing.

Results: It was found that treatment of cancer cells with the Snail-specific siRNA effectively downregulated the expression of Snail-1 in both mRNA and protein levels, and vimentin, CXCR4, and MMP-9 in mRNA level. However, it elevated the transcript levels of miR-34a and let-7a expressions. Furthermore, transfection of cancer cells with the Snail-specific siRNA significantly induced apoptosis in TE8 cells. Moreover, suppression of Snail-1 led to diminished cell migration.

Conclusion: It seems that Snail-specific siRNA can significantly interrupt esophageal cancer cell migration and reduce metastatic-related factors and induce miR-34a and let-7a in vitro. The bottom line is that therapeutic approaches via targeting Snail-1 can be used for ESCC treatment, suggesting that other possible target molecules for ESCC therapy require to be explored.

CTEN induces epithelial-mesenchymal transition (EMT) and metastasis in non small cell lung cancer cells

To explore the effects and mechanism of CTEN (COOH-terminus tensin-like molecule) on EMT, cell migration and invasion of Human lung adenocarcinoma cells. The pCMV-vector, pCMV-CTEN, Control-shRNA, and CTEN-shRNA were transfected into A549 and NCI-H1299 cells by Lipofectamine 2000. Transforming growth factor-β1(TGF-β1)and epithelial-mesenchymal transition (EMT) -related biomarkers were detected by eliseand western blot. The migration and invasion ability of A549 cells and NCI-H1299 were examined by scratch-wound assay and transwell assay respectively. We found compare with control group, the expression of TGF-β and mesenchymal markers in CTEN overexpression group were increased, and the epithelial marker was decreased, which induced the EMT process. Meanwhile, scratch-woundassay showed that the migration efficiency of A549 and NCI-H1299 cells in CTEN overexpression group were higher than that in control group.Transwell assay demonstrated that the number of cells that migrated and invaded through the membrane were obviously more than those in control group.Furthermore, Knockdown of CTEN partially reversed transforming growth factor-β1(TGF-β1)-induced changes in EMT markers. In conclusion, CTEN activated the expression of TGF-β1, thereby prompting EMT in lung adenocareinma cancer cells.

Cancer as a tissue: The significance of cancer-stromal interactions in the development, morphogenesis and progression of human upper digestive tract cancer

We review the significance of cancer-stromal interactions (CSIs) in the development, morphogenesis and progression of human gastric and esophageal cancer based on the data obtained from co-culture experiments. Orthotopic fibroblasts in the gastric cancer stroma not only promoted their growth by cancer cells but were also responsible for the mobility, morphogenesis and epithelial-to-mesenchymal transition (EMT) of the cancer cells through CSI. Bone marrow-derived mesenchymal stem cells could be part of the origin of cancer-associated fibroblasts (CAFs) of the gastric cancer providing an advantageous microenvironment for the restoration of cancer stem cells with the induction of the EMT. Tumor-associated macrophages (TAMs) may differentiate from bone marrow-derived monocytes/macrophages within the tumor microenvironment of esophageal cancer and participate in the growth and the progression of esophageal squamous cell carcinomas (ESCCs). Macrophages infiltrated into the intraepithelial neoplastic lesions of the esophagus may function as a biological promoter by promoting the growth and motility of squamous epithelia. Tumor cells build up "cancer as a tissue" by taking advantage of the existing network of growth factors, cytokines and chemokines through the interactions of TAMs, CAFs and cancer cells themselves.

Esophageal squamous cell carcinoma with low mitochondrial copy number has mesenchymal and stem-like characteristics, and contributes to poor prognosis

Alterations in mitochondrial DNA (mtDNA) copy numbers in various human cancers have been studied, but any such changes in esophageal squamous cell carcinoma (ESCC) are not established. In the present study, we investigated the correlation of mtDNA copy number with clinicopathologic features, prognosis, and malignant potential of ESCC. MtDNA copy numbers of resected specimens from 80 patients treated with radical esophagectomy were measured by quantitative real-time PCR analyses. Human ESCC cells, TE8 and TE11, were cultured, and depletion of mtDNA content was induced by knockdown of mitochondrial transcription factor A expression or treatment with ethidium bromide. The mRNA and protein expression, proliferation, invasion, and cell cycle were investigated. The results showed that the mtDNA copy number of cancerous portions was 56.0 (37.4-234.5) percent that of non-cancerous parts and significantly lower (p<0.01). Low mtDNA copy number in resected cancerous tissues was significantly correlated with pathological depth of tumor invasion (p = 0.045) and pathological stage (p = 0.025). Patients with lower mtDNA copy number had significantly poorer 5-year overall survival compared to patients with higher levels (p<0.01). The mtDNA-depleted TE8 and TE11 cells had morphological changes and proliferated more slowly than control cells under normoxia but proliferated at almost the same rate under hypoxic conditions. In mtDNA-depleted cells, E-cadherin mRNA expression was decreased, and N-cadherin, vimentin, zeb-1, and cd44 mRNA expression was increased. Immunoblotting and flow cytometry analysis also showed downregulated E-cadherin and upregulated N-cadherin and CD44 protein in mtDNA-depleted cells. Moreover, mtDNA-depleted cells had enhanced invasion, migration, and sphere formation abilities, and the cell cycle arrest at G0/G1 phase was induced in these cells. These results suggested that mtDNA-depleted ESCC cells had mesenchymal characteristics, cancer stemness, and tolerance to hypoxia, which played important role in cancer progression. In conclusion, a low copy number of mtDNA is associated with tumor progression in ESCC.

Differential expression and clinical significance of epithelial-mesenchymal transition markers among different histological types of triple-negative breast cancer

Background: Triple-negative breast cancer (TNBC) is a heterogeneous disease closely associated with epithelial-to-mesenchymal transition (EMT). This study aimed to investigate the role of EMT in metaplastic carcinoma.

Methods: E-cadherin, Slug, Twist and Vimentin levels were detected by immunohistochemistry in 167 TNBC tumors, including 145 invasive carcinomas of no special type (ICONSTs), 14 spindle cell carcinomas (SpCCs) and 8 matrix-producing carcinomas (MPCs).

Results: Nuclear Slug and Twist were more frequently detected in SpCC and MPC tumors than that in ICONST tumors (p<0.001). The rate of E-cadherin loss was much lower in the ICONST tumors than that in the SpCC and MPC tumors (p<0.001). Vimentin was expressed in all SpCC and MPC tumors. Furthermore, nuclear expression of Slug and Twist was positively associated with the cytoplasmic localization of Vimentin (p<0.001) and was inversely associated with membranous staining of E-cadherin (p<0.001). These trends were more apparent in the SpCC and MPC tumors than in the ICONST tumors. Follow-up data were available for 151 patients. The follow-up times ranged from 1 month to 11 years (mean: 74 m; median: 21 m). The median progression-free survival and overall survival times were 24 months (mean: 32 months) and 22 months (mean: 35 months), respectively. Tumor size, TNM stage and E-cadherin were found to be independent prognostic factors of TNBC.

Conclusions: EMT may play an important role in TNBC, especially in MPC and SpCC. Further researches are needed to confirm this finding. The results of this study may facilitate the future development of targeted therapies based on alterations in the EMT and stem cell markers.

Interplay between Notch1 and Notch3 promotes EMT and tumor initiation in squamous cell carcinoma

Notch1 transactivates Notch3 to drive terminal differentiation in stratified squamous epithelia. Notch1 and other Notch receptor paralogs cooperate to act as a tumor suppressor in squamous cell carcinomas (SCCs). However, Notch1 can be stochastically activated to promote carcinogenesis in murine models of SCC. Activated form of Notch1 promotes xenograft tumor growth when expressed ectopically. Here, we demonstrate that Notch1 activation and epithelial–mesenchymal transition (EMT) are coupled to promote SCC tumor initiation in concert with transforming growth factor (TGF)-β present in the tumor microenvironment. We find that TGFβ activates the transcription factor ZEB1 to repress Notch3, thereby limiting terminal differentiation. Concurrently, TGFβ drives Notch1-mediated EMT to generate tumor initiating cells characterized by high CD44 expression. Moreover, Notch1 is activated in a small subset of SCC cells at the invasive tumor front and predicts for poor prognosis of esophageal SCC, shedding light upon the tumor promoting oncogenic aspect of Notch1 in SCC.

Notch receptors can exert different roles in cancer. In this manuscript, the authors reveal that Notch1 activation and EMT promote tumor initiation and cancer cell heterogeneity in squamous cell carcinoma, while the repression of Notch3 by ZEB1 limits Notch1-induced differentiation, permitting Notch1-mediated EMT.

Tumor-educated mesenchymal stem cells promote pro-metastatic phenotype

Multipotent mesenchymal stem cells (MSCs) are recruited into tumor microenvironment in response to multiple signals produced by cancer cells. Molecules involved in their homing to tumors are the same inflammatory mediators produced by injured tissues: chemokines, cytokines and growth factors. When MSCs arrive into the tumor microenvironment these are “educated” to have pro-metastatic behaviour. Firstly, they promote cancer immunosuppression modulating both innate and adaptive immune systems. Moreover, tumor associated-MSCs trans-differentiating into cancer-associated fibroblasts can induce epithelial-mesenchymal-transition program in tumor cells. This process determinates a more aggressive phenotype of cancer cells by increasing their motility and invasiveness and favoring their dissemination to distant sites. In addition, MSCs are involved in the formation and modelling of pre-metastatic niches creating a supportive environment for colonization of circulating tumor cells.

The development of novel therapeutic approaches targeting the different functions of MSCs in promoting tumor progression as well as the mechanisms underlying their activities could enhance the efficacy of conventional and immune anti-cancer therapies.

Furthermore, many studies report the use of MSCs engineered to express different genes or as vehicle to specifically deliver novel drugs to tumors exploiting their strong tropism. Importantly, this approach can enhance local therapeutic efficacy and reduce the risk of systemic side effects.

Vimentin is a potential prognostic factor for tongue squamous cell carcinoma among five epithelial-mesenchymal transition-related proteins

We aimed to investigate the association of the expression levels of five epithelial-mesenchymal transition (EMT)-related proteins (Snail, Twist, E-cadherin, N-cadherin, and Vimentin) with tumorigenesis, pathologic parameters and prognosis in tongue squamous cell carcinoma (TSCC) patients by immunohistochemistry of tissue microarray. The expression levels of Snail, E-cadherin, N-cadherin and Vimentin were significantly different between the tumor adjacent normal and tumor tissues. In tumor tissues, lower E-cadherin and higher N-cadherin levels were associated with a higher grade of cell differentiation, advanced stage of disease, and lymph node metastasis. However, higher Vimentin expression was associated with poor cell differentiation and lymph node metastasis. Patients with low E-cadherin expression had poor disease-specific survival (DSS). Conversely, positive N-cadherin and higher Vimentin expression levels were associated with poor DSS and disease-free survival. Notably, our multivariate Cox regression model indicated that high Vimentin expression was an adverse prognostic factor for DSS in TSCC patients, even after the adjustment for cell differentiation, pathological stage, and expression levels of Snail, Twist, E-cadherin, and N-cadherin. Snail, E-cadherin, N-cadherin, and Vimentin were associated with tumorigenesis and pathological outcomes. Among the five EMT-related proteins, Vimentin was a potential prognostic factor for TSCC patients.

Programmed death-ligand 1 expression at tumor invasive front is associated with epithelial-mesenchymal transition and poor prognosis in esophageal squamous cell carcinoma

Programmed death‐ligand 1 (PD‐L1) plays a crucial role in the host immune system in cancer progression. The gene promoter region of PD‐L1 also contains a binding site for ZEB1, a transcription factor related to epithelial‐mesenchymal transition (EMT). The purpose of this study was to clarify the relationship between PD‐L1 and EMT and its clinical importance in esophageal squamous cell carcinoma (ESCC). PD‐L1 and ZEB1 expression at the tumor invasive front was examined by immunohistochemistry in resected specimens from 90 patients with ESCC who underwent surgery without preoperative therapy, and their expression and clinicopathological factors were compared. ZEB1 and PD‐L1 expression was determined in TE8 cells, which demonstrate the EMT phenotype, following ZEB1 knockdown by siZEB1. TE5, TE6 and TE11 cells with non‐EMT phenotype were also used for studies of TGF‐β1‐dependent EMT induction and ZEB1 and PD‐L1 expression. In cases of high PD‐L1 expression at the invasive front, significantly greater depth of tumor invasion, EMT, and less CD8⁺ lymphocyte infiltration were observed. High PD‐L1 expression was also associated with worse overall and relapse‐free survival. A correlation was observed between PD‐L1 and ZEB1 expression. In TE8 cells, siZEB1 suppressed PD‐L1 and promoted E‐cadherin mRNA and protein expression. TGF‐β1 induced EMT and surface expression of PD‐L1 in TE5, TE6 and TE11 cell lines. PD‐L1 expression at the ESCC invasive front was related to ZEB1 expression, EMT and poor prognosis. We suggest that a cooperative mechanism bridging between tumor immune avoidance and EMT contributes to tumor malignancy in ESCC.

MicroRNA-30a Regulation of Epithelial-Mesenchymal Transition in Diabetic Cataracts Through Targeting SNAI1

Epithelial-mesenchymal transition (EMT) is a highly conserved and fundamental process in development, fibrosis, and metastasis. During the process, epithelial cells lose their morphology and transcriptional program, and transdifferentiate to mesenchymal cells. It has been reported that lens epithelial cells undergo EMT during cataract formation, and regulation of microRNAs on genes is associated with lens development. However, the molecular mechanisms of this regulation in diabetic cataract still need to be investigated. In the present study, the expression of E-cadherin was downregulated, while the expression of alpha-SMA and vimentin was upregulated in diabetic cataract tissues and the in vitro model, suggesting the involvement of EMT in diabetic cataract formation. Results of miRNA profiling demonstrated that miR-30a was markedly downregulated in diabetic cataract tissues. Overexpression of miR-30a-5p decreased SNAI1, a known modulator of EMT, and the expression of vimentin and alpha-SMA in our diabetic cataract model in vitro. It is concluded that EMT is involved in human diabetic cataract, and upregulation of miR-30a can repress EMT through its targeting of SNAI1 in lens epithelial cells, which make miR-30a a novel target of therapeutic intervention for human diabetic cataract.

Autophagy supports generation of cells with high CD44 expression via modulation of oxidative stress and Parkin-mediated mitochondrial clearance

High CD44 expression is associated with enhanced malignant potential in esophageal squamous cell carcinoma (ESCC), amongst the deadliest of all human carcinomas. Although alterations in autophagy and CD44 expression are associated with poor patient outcomes in various cancer types, the relationship between autophagy and cells with high CD44 expression remains incompletely understood. In transformed esophageal keratinocytes, CD44^Low-CD24^High (CD44L) cells give rise to CD44^High-CD24^−/Low (CD44H) cells via epithelial-mesenchymal transition (EMT) in response to transforming growth factor (TGF)-β. We couple patient samples and xenotransplantation studies with this tractable in vitro system of CD44L to CD44H cell conversion to investigate the functional role of autophagy in generation of cells with high CD44 expression. We report that high expression of the autophagy marker cleaved LC3 expression correlates with poor clinical outcome in ESCC. In ESCC xenograft tumors, pharmacological autophagy inhibition with chloroquine derivatives depletes cells with high CD44 expression while promoting oxidative stress. Autophagic flux impairment during EMT-mediated CD44L to CD44H cell conversion in vitro induces mitochondrial dysfunction, oxidative stress and cell death. During CD44H cell generation, transformed keratinocytes display evidence of mitophagy, including mitochondrial fragmentation, decreased mitochondrial content and mitochondrial translocation of Parkin, essential in mitophagy. RNA interference-mediated Parkin depletion attenuates CD44H cell generation. These data suggest that autophagy facilitates EMT-mediated CD44H generation via modulation of redox homeostasis and Parkin-dependent mitochondrial clearance. This is the first report to implicate mitophagy in regulation of tumor cells with high CD44 expression, representing a potential novel therapeutic avenue in cancers where EMT and CD44H cells have been implicated, including ESCC.

SIX1 maintains tumor basal cells via transforming growth factor-β pathway and associates with poor prognosis in esophageal cancer

Esophageal squamous cell carcinoma (ESCC) is one of the most common malignant tumors. Although improvement in both surgical techniques and neoadjuvant chemotherapy has been achieved, the 5-year survival rate of locally advanced tumors was, at best, still 55%. Therefore, elucidation of mechanisms of the malignancy is eagerly awaited. Epithelial-mesenchymal transition (EMT) by transforming growth factor-β (TGF-β) has been reported to have critical biological roles for cancer cell stemness, whereas little is known about it in ESCC. In the current study, a transcriptional factor SIX1 was found to be aberrantly expressed in ESCCs. SIX1 cDNA transfection induced overexpression of transforming growth factors (TGFB1 and TGFB2) and its receptor (TGFBR2). Cell invasion was reduced by SIX1 knockdown and was increased in stable SIX1-transfectants. Furthermore, the SIX1-transfectants highly expressed tumor basal cell markers such as NGFR, SOX2, ALDH1A1, and PDPN. Although mock-transfectants had only a 20% PDPN-high population, SIX1-transfectants had 60-70%. In two sets of 42 and 85 ESCC patients receiving surgery alone or neoadjuvant chemoradiotherapy followed by surgery, the cases with high SIX1 mRNA and protein expression level significantly showed a poor prognosis compared with those with low levels. These SIX1 high cases also expressed the above basal cell markers, but suppressed the differentiation markers. Finally, TGF-β signaling blockade suppressed ESCC cell growth in association with the reduction of PDPN-positive tumor basal cell population. The present results suggest that SIX1 accelerates self-renewal of tumor basal cells, resulting in a poor prognosis for ESCC patients.

Podoplanin expression is correlated with the prognosis of lung squamous cell carcinoma

Podoplanin is a 38 kDa transmembrane protein that is involved in cell migration and cancer cell invasion. Some studies have reported that podoplanin expression was correlated with poor prognosis in lung squamous cell carcinoma (SqCC). However, there have been no clinicopathological studies of podoplanin membrane expression and localization in lung SqCC. In this study, we focused on the intensity and localization of podoplanin membrane expression, and its clinicopathological significance for lung SqCC. Strong membrane expression of podoplanin was significantly associated with lymph node metastasis, lymphatic invasion, and histological differentiation. Cases with strong podoplanin expression at cell membrane showed better prognosis of lung SqCC (HR, 3.301). Peripheral localization of podoplanin was associated with tumor size, lymphatic invasion, and histological differentiation. Cases with peripheral podoplanin expression showed favorable prognosis of lung SqCC (HR, 2.830). Both strong membrane expression and peripheral expression of podoplanin were independent predictors of mortality of lung SqCC (HR, 2.869; HR, 2.443, respectively). The cases with strong or peripheral podoplanin expression showed better overall survival (P = 0.001, both). Podoplanin intensity is significantly associated with podoplanin localization (P < 0.001), and its correlation coefficient was 0.678. We concluded that podoplanin membrane expression, not only its localization, is a useful prognostic indicator of lung SqCC patients.

Radiation induces the generation of cancer stem cells: A novel mechanism for cancer radioresistance

Radioresistance remains a major obstacle for the radiotherapy treatment of cancer. Previous studies have demonstrated that the radioresistance of cancer is due to the existence of intrinsic cancer stem cells (CSCs), which represent a small, but radioresistant cell subpopulation that exist in heterogeneous tumors. By contrast, non-stem cancer cells are considered to be radiosensitive and thus, easy to kill. However, recent studies have revealed that under conditions of radiation-induced stress, theoretically radiosensitive non-stem cancer cells may undergo dedifferentiation subsequently obtaining the phenotypes and functions of CSCs, including high resistance to radiotherapy, which indicates that radiation may directly result in the generation of novel CSCs from non-stem cancer cells. These findings suggest that in addition to intrinsic CSCs, non-stem cancer cells may also contribute to the relapse and metastasis of cancer following transformation into CSCs. This review aims to investigate the radiation-induced generation of CSCs, its association with epithelial-mesenchymal transition and its significance with regard to the radioresistance of cancer.

The epithelial-mesenchymal transition phenotype of metastatic lymph nodes impacts the prognosis of esophageal squamous cell carcinoma patients

Epithelial-mesenchymal transition (EMT) plays a key role in tumor metastasis, but the significance of EMT phenotype to the prognosis of esophageal squamous cell carcinoma (ESCC) patients remains unclear. We used immunohistochemistry to examine the expression of the EMT-related proteins E-cadherin, N-cadherin and vimentin in samples of T3N1-3M0 ESCC from 155 primary tumors (PTs) with paired metastatic lymph nodes (MLNs) and 58 PTs without paired MLNs. Based on the expression pattern of the EMT markers, PTs and MLNs were classified as EMT wild, hybrid, null or complete type. The hybrid (42.7%) and complete (39.4%) types predominated among PTs, whereas the wild (34.2%) and hybrid (52.9%) types predominated among MLNs, and EMT phenotypes differed between the paired PTs and MLNs (P < 0.001). Univariate analysis revealed that, for PTs, the EMT phenotype was associated with N-stage (P = 0.039) but not patient survival, and that patients with complete or hybrid type MLNs had better overall survival (OS, P = 0.001) and disease-free survival (DFS, P = 0.005) than patients with null and wild type MLNs, especially those with N1-stage disease (P = 0.017 for OS, and P = 0.017 for DFS, respectively). Multivariate analysis revealed that wild and null type MLNs as well as older age and N2-3 stage were independent predictors of OS and DFS (P < 0.05). Thus MLNs exhibit EMT phenotypes that are distinct from those of their PT and may serve as a novel independent prognostic indicator in ESCC.

Concise Review: Stem Cells and Epithelial-Mesenchymal Transition in Cancer: Biological Implications and Therapeutic Targets

Cancer stem cells (CSCs) constitute a small subpopulation of cancer cells with stem-like properties that are able to self-renew, generate differentiated daughter cells, and give rise to heterogeneous tumor tissue. Tumor heterogeneity is a hallmark of cancer and underlies resistance to anticancer therapies and disease progression. The epithelial-mesenchymal transition (EMT) is a reversible phenomenon that is mediated by EMT-inducing transcription factors (EMT-TFs) and plays an important role in normal organ development, wound healing, and the invasiveness of cancer cells. Recent evidence showing that overexpression of several EMT-TFs is associated with stemness in cancer cells has suggested the existence of a link between EMT and CSCs. In this review, we focus on the roles of CSCs and EMT signaling in driving tumor heterogeneity. A better understanding of the dynamics of both CSCs and EMT-TFs in the generation of tumor heterogeneity may provide a basis for the development of new treatment options for cancer patients. Stem Cells 2016;34:1997-2007.

Six family of homeobox genes and related mechanisms in tumorigenesis protocols

In recent years, the homeobox gene superfamily has been introduced as a master regulator in downstream target genes related to cell development and proliferation. An indispensable role of this family involved in organogenesis development has been widely demonstrated since expression of Six family led to a distinct increase in development of various organs. These functions of Six family genes are primarily based on structure as well as regulatory role in response to external or internal stimuli. In addition to these roles, mutation or aberrant expression of Six family plays a fundamental role in initiation of carcinogenesis, a multistep process including transformation, proliferation, angiogenesis, migration, and metastasis. This suggests that the Six superfamily members can be considered as novel target molecules to inhibit tumor growth and progression. This review focuses on the structure, function, and mechanisms of the Six family in cancer processes and possible strategies to apply these family members for diagnostic, prognostic, and therapeutic purposes.

Homeostatic Signaling by Cell-Cell Junctions and Its Dysregulation during Cancer Progression

The transition of sessile epithelial cells to a migratory, mesenchymal phenotype is essential for metazoan development and tissue repair, but this program is exploited by tumor cells in order to escape the confines of the primary organ site, evade immunosurveillance, and resist chemo-radiation. In addition, epithelial-to-mesenchymal transition (EMT) confers stem-like properties that increase efficiency of colonization of distant organs. This review evaluates the role of cell–cell junctions in suppressing EMT and maintaining a quiescent epithelium. We discuss the conflicting data on junctional signaling in cancer and recent developments that resolve some of these conflicts. We focus on evidence from breast cancer, but include other organ sites where appropriate. Current and potential strategies for inhibition of EMT are discussed.

The role of Snail1 transcription factor in colorectal cancer progression and metastasis

Snail1 is a zinc-finger transcription factor, which plays a role in colorectal cancer development by silencing E-cadherin expression and inducing epithelialmesenchymal transition (EMT). During EMT tumour cells acquire a mesenchymal phenotype that is responsible for their invasive activities. Consequently, Snail1 expression in colorectal cancer is usually associated with progression and metastasis. Some studies revealed that about 77% of colon cancer samples display Snail1 immunoreactivity both in activated fibroblasts and in carcinoma cells that have undergone EMT. Therefore, expression of this factor in the stroma may indicate how many cells possess the abilities to escape from the primary tumour mass, invade the basal lamina and colonise distant target organs. Blocking snail proteins activity has the potential to avert cancer cell metastasis by interfering with such cellular processes as remodelling of the actin cytoskeleton, migration and invasion, which are clearly associated with the aggressive phenotype of the disease. Moreover, the link between factors from the snail family and cancer stem cells suggests that inhibitory agents may also prove their potency as inhibitors of cancer recurrence.

Co-Expression of TWIST1 and ZEB2 in Oral Squamous Cell Carcinoma Is Associated with Poor Survival

Oral squamous cell carcinoma (OSCC) is an aggressive disease accounting for more than 260,000 cancer cases diagnosed and 128,000 deaths worldwide. A large majority of cancer deaths result from cancers that have metastasized beyond the primary tumor. The relationship between genetic changes and clinical outcome can reflect the biological events that promote cancer's aggressive behavior, and these can serve as molecular markers for improved patient management and survival. To this end, epithelial-mesenchymal transition (EMT) is a major process that promotes tumor invasion and metastasis, making EMT-related proteins attractive diagnostic biomarkers and therapeutic targets. In this study, we used immunohistochemistry to study the expression of a panel of transcription factors (TWIST1, SNAI1/2, ZEB1 and ZEB2) and other genes intimately related to EMT (CDH1 and LAMC2) at the invasive tumor front of OSCC tissues. The association between the expression of these proteins and clinico-pathological parameters were examined with Pearson Chi-square and correlation with survival was analyzed using Kaplan Meier analysis. Our results demonstrate that there was a significant differential expression of CDH1, LAMC2, SNAI1/2 and TWIST1 between OSCC and normal oral mucosa (NOM). Specifically, CDH1 loss was significantly associated with Broder's grading, while diffused LAMC2 was similarly associated with non-cohesive pattern of invasion. Notably, co-expression of TWIST1 and ZEB2 in OSCC was significantly associated with poorer overall survival, particularly in patients without detectable lymph node metastasis. This study demonstrates that EMT-related proteins are differentially expressed in OSCC and that the co-expression of TWIST1 and ZEB2 could be of clinical value in identifying patients with poor survival for appropriate patient management.

Expression of podoplanin and vimentin is correlated with prognosis in esophageal squamous cell carcinoma

Podoplanin is a small membrane mucin, which is involved in cell migration and cancer cell invasion. However, the roles of podoplanin in esophageal squamous cell carcinoma (ESCC) are poorly understood. In the present study, 139 cases of surgically resected ESCC were analyzed and the clinicopathological significance of podoplanin membrane expression in ESCC was demonstrated. Podoplanin expression was positive in 66.2% (92/139) of ESCC samples; with weak expression in 32.4% (45/139), and strong expression in 33.8% (47/139). Membrane expression of podoplanin was significantly associated with tumor status (P=0.001), venous invasion (P=0.035) and Union for International Cancer Control stage (P=0.029). Patients who exhibited strong podoplanin expression, were shown to have a poorer prognosis [hazard ratio (HR), 3.949; 95% confidence interval (CI), 2.001–7.794]. Expression of vimentin, a mesenchymal marker, was detected in 49 cases (35.3%) and was associated with venous invasion (P=0.020). Vimentin-positive cases were also more likely to have a worse prognosis than vimentin-negative cases (HR, 2.161; 95% CI, 1.300–3.592). Podoplanin membrane expression was significantly correlated with vimentin cytoplasmic expression in ESCC (P<0.001). The present study confirmed that podo-planin and vimentin are independent predictors of mortality (HR, 3.084; 95% CI, 1.543–6.164). These results suggest that podoplanin membrane expression results in epithelial-mesenchymal transition and promotes aggressive invasion in human ESCC.

Ghrelin promotes renal cell carcinoma metastasis via Snail activation and is associated with poor prognosis

Ghrelin is an appetite-regulating molecule that promotes growth hormone (GH) release and food intake through growth hormone secretagogue receptor (GHS-R). Recently, high ghrelin levels have been detected in various types of human cancer. Ghrelin expression is observed in proximal and distal renal tubules, where renal cell carcinoma (RCC) arises. However, whether ghrelin is up-regulated and promotes renal cell carcinogenesis remains obscure. In this study, we observed that ghrelin was highly expressed in renal tumours, especially in metastatic RCC. In addition, high ghrelin levels correlated with poor outcome, lymph node and distant metastasis. The addition of ghrelin promoted the migration ability of RCC cell lines 786-0, ACHN and A-498. Furthermore, knockdown of ghrelin expression reduced in vitro migration and in vivo metastasis, suggesting a requirement for ghrelin accumulation in the microenvironment for RCC metastasis. Analysis of microarray signatures using Ingenuity Pathway Analysis (IPA) and MetaCore pointed to the potential regulation by ghrelin of Snail, a transcriptional repressor of E-cadherin. We further observed that Ghrelin increased the expression, nuclear translocation and promoter-binding activity of Snail. Snail silencing blocked the ghrelin-mediated effects on E-cadherin repression and cell migration. Snail-E-cadherin regulation was mediated by GHS-R-triggered Akt phosphorylation at Ser473 and Thr308. Pretreatment with PI3K inhibitors, LY294002 and wortmannin, as well as Akt siRNA, decreased ghrelin-induced Akt phosphorylation, Snail promoter binding activity and migration. Taken together, our findings indicate that ghrelin can activate Snail function via the GHS-R-PI3K-Akt axis, which may contribute to RCC metastasis. The microarray raw data were retrieved from the Cancer Genome Atlas (TCGA) [KIRC gene expression (IlluminaHiSeq) dataset].

Cyr61 promotes CD204 expression and the migration of macrophages via MEK/ERK pathway in esophageal squamous cell carcinoma

Tumor-associated macrophages (TAMs) are known to be involved in the progression of various human malignancies. We previously demonstrated that CD204 was a useful marker for TAMs contributing to the angiogenesis, progression, and prognosis of human esophageal squamous cell carcinoma (ESCC). We also showed that conditioned media of ESCC cell lines induced CD204 expression in THP-1 human monocytic leukemia cells. Here, we performed a cDNA microarray analysis between THP-1 cells stimulated with TPA (macrophage [MΦ]-like THP-1 cells) treated with and without conditioned medium of ESCC cell line to clarify the molecular characteristics of TAMs in ESCC. From the microarray data, we discovered that Cyr61 was induced in CD204-positive-differentiated THP-1 cells (TAM-like THP-1 cells). In the ESCC microenvironment, not only cancer cells but also TAMs expressed Cyr61. Interestingly, the expression levels of Cyr61 showed a significant positive correlation with the number of CD204-positive macrophages in ESCCs by immunohistochemistry. Recombinant human Cyr61 (rhCyr61) promoted cell migration and induced the expression of CD204 along with the activation of the MEK/ERK pathway in MΦ-like THP-1 cells. Pretreatment with a MEK1/2 inhibitor significantly inhibited not only the Cyr61-mediated migration but also the CD204 expression in the MΦ-like THP-1 cells. These results suggest that Cyr61 may contribute to the expression of CD204 and the promotion of cell migration via the MEK/ERK pathway in TAMs in the ESCC microenvironment.