Expression of cadherins in benign, borderline, and malignant ovarian epithelial tumors: a clinicopathologic study of 60 cases

Clonorchis sinensis legumain promotes migration and invasion of cholangiocarcinoma cells via regulating tumor-related molecules

BACKGROUND

Clonorchis sinensis infection causes serious pathological changes in the bile duct and is highly correlated with cholangiocarcinoma. The excretory-secretory products (ESP) of C. sinensis play a critical role in the oncogenesis and progression of cholangiocarcinoma, while the components and precise mechanism remain unclear. Here, we evaluated the function of C. sinensis legumain (Cslegumain) in promoting the invasion and migration of cholangiocarcinoma cells and the mechanism involved.

METHODS

The structural and molecular characteristics of Cslegumain were predicted and analyzed using the online program Phyre2. Quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemical staining were performed to test the transcriptional level of Cslegumain and its localization in the adult. Native Cslegumain was detected by western blotting assay. The effects of Cslegumain on the proliferation, invasion and migration of cholangiocarcinoma cells were checked using CCK-8 assay, Matrigel transwell assay and scratch wound healing assay. Expression levels of tumor-related molecules regulated by Cslegumain were evaluated by qRT-PCR and western blotting assay.

RESULTS

Cslegumain showed high similarity with human legumain in the secondary and tertiary structures and displayed higher transcriptional levels in the adult worm than in the metacercariae. Native Cslegumain was detected in a catalytic form and was localized mainly in the intestine of the C. sinensis adult and epithelial cells of the intrahepatic bile duct. After transfection into RBE cells, Cslegumain showed high ability in promoting the invasion and migration but not the proliferation of cholangiocarcinoma RBE cells. Furthermore, the expression levels of some molecules including E-cadherin and N-cadherin were downregulated, while the levels of α-actinin 4, β-catenin and inducible nitric oxide synthase (iNOS) were upregulated.

CONCLUSIONS

Our findings indicated that Cslegumain showed very similar structures as those of human legumain and could promote the invasion and migration of cholangiocarcinoma cells by regulating some tumor-related molecules.

Prognostic value of E-Cadherin and its tumor suppressor role in Saudi women with advanced epithelial ovarian cancer

The extracellular matrix (ECM) disruption and cytoskeleton reorganization are crucial events in tumor proliferation and invasion. E-Cadherin (E-CAD) is a member of cell adhesion molecules involved in cell-cell junctions and ECM stability. The loss of E-CAD expression is associated with cancer progression and metastasis. This retrospective study aimed to assess E-CAD protein expression in ovarian cancer (OC) tissues and to evaluate its prognostic value. Patients and Methods: 143 formalin-fixed and paraffin-embedded (FFPE) blocks of primary advanced stages OC were retrieved and used to construct Tissue microarrays. Automated immunohistochemistry technique was performed to evaluate E-CAD protein expression patterns in OC. Results: E-CAD protein expression was significantly correlated with OC histological subtype (p < 0.0001), while borderline significant correlations were observed with both tumor grade (p = 0.06) and stage (p = 0.07). Interestingly, Kaplan-Meier survival analysis showed that OC patients with membranous E-CAD expression survived longer than those with no E-CAD expression mainly those at advanced stages (p < 0.009). Further in silico analysis confirms the key roles of E-CAD in OC molecular functions. Conclusion: we reported a prognosis value of membranous E-CAD in advanced stage OC patients. Further validation using larger cohorts is recommended to extract clinically relevant outcomes towards better OC management and individualized oncology.

Folate Receptor Alpha Is Preferentially Expressed in the Carcinoma Component of Endometrial Carcinosarcomas: A Potential Target for Adjuvant Therapy

Carcinosarcomas (CSs) of the endometrium are biphasic malignancies, composed of high-grade carcinomatous and sarcomatous components. Surgical stage and pathologic characteristics are the most important prognostic findings, with a 5-yr survival of 15% to 30% in advance stage disease. Folate receptor alpha (FRA) overexpression has been observed in endometrial carcinomas and not yet studied in CSs. This study evaluates semiquantitative expression of FRA in both carcinomatous and sarcomatous components of CSs on whole tissue sections. Immunohistochemistry for FRA expression was performed and extent and intensity of staining were recorded for each case for both histologic components. A total of 46 cases were stained for FRA. The majority of these (40/46, 87%) showed FRA staining at variable intensity in the carcinomatous component, stronger in serous carcinomas and high-grade endometrioid, while only a small subset of tumors demonstrated weak staining in the sarcomatous component (2/46, 4.35%). CS is known to be associated with poor prognosis and adjuvant therapy is recommended even in low stage disease. Serous and high-grade endometrioid carcinomas are the most common carcinomatous components of CSs and are known to show consistently high FRA expression. Folate plays a role in tumor cell migration and loss of cellular adhesion, which are key steps in epithelial-mesenchymal transition, the process by which CS develops from carcinoma cells. Our study shows expression of FRA in the carcinomatous component of almost all CS cases (87%), further favoring FRA as a target for adjuvant treatment. While expression of FRA in the sarcomatous component was rarely observed, the carcinomatous component being associated with metastatic potential underscores the importance of anti-FRA therapy for systemic disease control.

Phase I Study of P-cadherin-targeted Radioimmunotherapy with 90Y-FF-21101 Monoclonal Antibody in Solid Tumors

PURPOSE

⁹⁰Y-FF-21101 is an Yttrium-90-conjugated, chimeric mAb that is highly specific for binding to human placental (P)-cadherin, a cell-to-cell adhesion molecule overexpressed and associated with cancer invasion and metastatic dissemination in many cancer types. We report the clinical activity of ⁹⁰Y-FF-21101 in a first-in-human phase I study in patients with advanced solid tumors.

PATIENTS AND METHODS

The safety and efficacy of ⁹⁰Y-FF-21101 were evaluated in a phase I 3+3 dose-escalation study in patients with advanced solid tumors (n = 15) over a dose range of 5-25 mCi/m². Dosimetry using ¹¹¹In-FF-21101 was performed 1 week prior to assess radiation doses to critical organs. Patients who demonstrated clinical benefit received repeated ⁹⁰Y-FF-21101 administration every 4 months.

RESULTS

¹¹¹In-FF-21101 uptake was observed primarily in the spleen, kidneys, testes, lungs, and liver, with tumor uptake observed in the majority of patients. Organ dose estimates for all patients were below applicable limits. P-cadherin expression H-scores ranged from 0 to 242 with 40% of samples exhibiting scores ≥100. FF-21101 protein pharmacokinetics were linear with increasing antibody dose, and the mean half-life was 69.7 (±12.1) hours. Radioactivity clearance paralleled antibody clearance. A complete clinical response was observed in a patient with clear cell ovarian carcinoma, correlating with a high tumor P-cadherin expression. Stable disease was observed in a variety of other tumor types, without dose-limiting toxicity.

CONCLUSIONS

The favorable safety profile and initial antitumor activity observed for ⁹⁰Y-FF-21101 warrant further evaluation of this radioimmunotherapeutic (RIT) approach and provide initial clinical data supporting P-cadherin as a potential target for cancer treatment.

Adipocytes: active facilitators in epithelial ovarian cancer progression?

There is growing evidence that adipocytes play important roles in the progression of multiple cancers. Moreover, in obesity, adipocytes alter their original functions and contribute to the metabolic and inflammatory changes of adipose tissue microenvironment, which can further enhance tumor development. At present, the roles of adipocytes in the pathogenesis of epithelial ovarian cancer (EOC) are far from being fully elucidated. Herein, we summarized the recent advances in understanding the roles of adipocytes in EOC progression. Adipocytes, close neighbors of EOC tissue, promote EOC growth, invasion, metastasis and angiogenesis through adipokine secretion, metabolic remodeling and immune microenvironment modulation. Moreover, adipocytes are important therapeutic targets and may work as useful anticancer drug delivery depot for EOC treatment. Furthermore, adipocytes also act as a therapeutic obstacle for their involvement in EOC treatment resistance. Hence, better characterization of the adipocytes in EOC microenvironment and the crosstalk between adipocytes and EOC cells may provide insights into EOC progression and suggest novel therapeutic opportunities.

EMT, MET, Plasticity, and Tumor Metastasis

Cancer cell identity and plasticity are required in transition states, such as epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET), in primary tumor initiation, progression, and metastasis. The functional roles of EMT, MET, and the partial state (referred to as pEMT) may vary based on the type of tumor, the state of dissemination, and the degree of metastatic colonization. Herein, we review EMT, MET, pEMT, and plasticity in the context of tumor metastasis.

BRMS1L suppresses ovarian cancer metastasis via inhibition of the β-catenin-wnt pathway

A low level of breast cancer metastasis suppressor 1-like (BRMS1L) has been implicated in tumour metastasis involving breast cancer and other cancers. It remains unclear whether BRMS1L is involved in epithelial ovarian cancer (EOC) metastasis and what the molecular mechanism of BRMS1L is in suppressing EOC metastasis. In this study, we examined the mRNA expression and protein level of BRMS1L by screening EOC patients. Our results show that BRMS1L expression is downregulated in EOC patients compared to that in normal people and negatively correlated to pathological stages of EOC. We further explored examining epithelial to mesenchymal transition (EMT) as the molecular mechanism of BRMS1L in cancer cell metastasis. The overexpression of BRMS1L inhibits EOC cell migration and invasion, and this inhibition is correlated to the inactivation of EMT and Wnt/β-catenin signalling in vitro. Knockdown of BRMS1L by shRNA promotes EOC metastasis, enhances EMT process and activates Wnt/β-catenin signalling. These results suggest that BRMS1L plays a critical role in the suppression of ovarian cancer metastasis, and BRMS1L can be considered as a prognostic biomarker and potential therapeutic target for EOC patients.

Sprouty2 inhibits amphiregulin-induced down-regulation of E-cadherin and cell invasion in human ovarian cancer cells

Similar to Drosophila Sprouty (SPRY), mammalian SPRY proteins inhibit the receptor tyrosine kinase-mediated activation of cellular signaling pathways. SPRY2 expression levels have been shown to be down-regulated in human ovarian cancer, and patients with low SPRY2 expression have significantly poorer survival than those with high SPRY2 expression. In addition, epidermal growth factor receptor (EGFR) is overexpressed in human ovarian cancer and is associated with more aggressive clinical behavior and a poor prognosis. Amphiregulin (AREG), the most abundant EGFR ligand in ovarian cancer, binds exclusively to EGFR and stimulates ovarian cancer cell invasion by down-regulating E-cadherin expression. However, thus far, the roles of SPRY2 in AREG-regulated E-cadherin expression and cell invasion remain unclear. In the present study, we show that treatment with AREG up-regulated SPRY2 expression by activating the EGFR-mediated ERK1/2 signaling pathway in two human ovarian cancer cell lines, SKOV3 and OVCAR5. In addition, overexpression of SPRY2 attenuated the AREG-induced down-regulation of E-cadherin by inhibiting the induction of the E-cadherin transcriptional repressor, Snail. Moreover, SPRY2 overexpression attenuated AREG-stimulated cell invasion and proliferation. This study reveals that SPRY2 acts as a tumor suppressor in human ovarian cancer and illustrates the underlying mechanisms that can be used as possible targets for the development of novel therapeutics.

Targeting folate receptor alpha for cancer treatment

Promising targeted treatments and immunotherapy strategies in oncology and advancements in our understanding of molecular pathways that underpin cancer development have reignited interest in the tumor-associated antigen Folate Receptor alpha (FRα). FRα is a glycosylphosphatidylinositol (GPI)-anchored membrane protein. Its overexpression in tumors such as ovarian, breast and lung cancers, low and restricted distribution in normal tissues, alongside emerging insights into tumor-promoting functions and association of expression with patient prognosis, together render FRα an attractive therapeutic target. In this review, we summarize the role of FRα in cancer development, we consider FRα as a potential diagnostic and prognostic tool, and we discuss different targeted treatment approaches with a specific focus on monoclonal antibodies. Renewed attention to FRα may point to novel individualized treatment approaches to improve the clinical management of patient groups that do not adequately benefit from current conventional therapies.

Betacellulin induces Slug-mediated down-regulation of E-cadherin and cell migration in ovarian cancer cells

Epithelial ovarian cancer is the leading cause of death among gynaecological cancers. Previous studies have demonstrated that epidermal growth factor receptor (EGFR) ligands can induce ovarian cancer cell invasion by down-regulating E-cadherin. Betacellulin is a unique member of the EGF family. It is overexpressed in a variety of cancers and is associated with reduced survival. However, the biological functions and clinical significance of betacellulin in ovarian cancer remain unknown. In the current study, we tested the hypothesis that betacellulin induces ovarian cancer cell migration by suppressing E-cadherin expression. Treatment of SKOV3 and OVCAR5 ovarian cancer cell lines with betacellulin down-regulated E-cadherin, but not N-cadherin. In addition, betacellulin treatment increased the expression of Snail and Slug, and these effects were completely blocked by pre-treatment with EGFR inhibitor AG1478. Interestingly, only knockdown of Slug reversed the down-regulation of E-cadherin by betacellulin. Betacellulin treatment induced the activation of both the MEK-ERK and PI3K-Akt signaling pathways, and it also significantly increased ovarian cancer cell migration. Importantly, the effects of betacellulin on E-cadherin, Slug and cell migration were attenuated by pre-treatment with either U0126 or LY294002. Our results suggest that betacellulin induces ovarian cancer migration and Slug-dependent E-cadherin down-regulation via EGFR-mediated MEK-ERK and PI3K-Akt signaling.

E-cadherin: Its dysregulation in carcinogenesis and clinical implications

E-cadherin is a transmembrane glycoprotein which connects epithelial cells together at adherens junctions. In normal cells, E-cadherin exerts its tumour suppressing role mainly by sequestering β-catenin from its binding to LEF (Lymphoid enhancer factor)/TCF (T cell factor) which serves the function of transcribing genes of the proliferative Wnt signaling pathway. Despite the ongoing debate on whether the loss of E-cadherin is the cause or effect of epithelial-mesenchymal transition (EMT), E-cadherin functional loss has frequently been associated with poor prognosis and survival in patients of various cancers. The dysregulation of E-cadherin expression that leads to carcinogenesis happens mostly at the epigenetic level but there are cases of genetic alterations as well. E-cadherin expression has been linked to the cellular functions of invasiveness reduction, growth inhibition, apoptosis, cell cycle arrest and differentiation. Studies on various cancers have shown that these different cellular functions are also interdependent. Recent studies have reported a rapid expansion of E-cadherin clinical relevance in various cancers. This review article summarises the multifaceted effect E-cadherin expression has on cellular functions in the context of carcinogenesis as well as its clinical implications in diagnosis, prognosis and therapeutics.

An updated meta-analysis of the prognostic value of decreased E-cadherin expression in ovarian cancer

Decreased epithelial cadherin (E-cadherin) expression is hypothesized to be related to poor prognosis of ovarian cancer, but the predictive value is still inconsistent. We conducted an updated meta-analysis with a total of 16 studies enrolling 1720 patients to estimate the prognostic value of decreased E-cadherin expression in ovarian cancer. Reduced expression of E-cadherin was significantly associated to poor overall survival (HR = 1.74, 95% CI: 1.40–2.17) and progression-free survival (HR = 1.45, 95% CI: 1.12–1.86) with a large heterogeneity for overall survival. In addition, we found that decreased expression of E-cadherin was significantly correlated with International Federation of Gynecology and Obstetrics grade (HR = 3.74, 95% CI: 2.24–6.23), E-cadherin membranous (HR = 1.47, 95% CI: 1.01–2.14), pathologic grade (HR = 1.41, 95% CI: 1.01–1.97), residual tumor size (HR = 2.72, 95% CI: 1.99–3.72), and surgery (HR = 3.21, 95% CI: 1.19–8.67). Our finding suggests that decreased E-cadherin expression may be a predictor of poor ovarian cancer prognosis.

E-cadherin expression as a prognostic factor in patients with ovarian cancer: a meta-analysis

The prognostic role of epithelial cadherin (E-cadherin) downregulation in ovarian cancer has been assessed for years while the results remain inconclusive. The aim of our study was to assess this issue. Eligible studies were identified through searches of PubMed, EMBASE and Cochrane Database. In total, 1562 patients from 17 studies were included to assess the association between E-cadherin expression and overall survival/progression-free survival and clinicopathological characteristics of ovarian cancer patients. Hazard ratios (HRs) or odds ratios (ORs) with 95% confidence interval (95% CI) were calculated to estimate the effect. The quality of 17 studies was evaluated using the Newcastle Ottawa Quality Assessment Scale. We also performed subgroup analysis, publication bias and sensitivity analysis in this meta-analysis. The results showed that negative E-cadherin expression significantly predicted poor overall survival of ovarian cancer patients (HR = 1.90, 95% CI = 1.50–2.40). However, negative E-cadherin was not associated with poor progression-free survival (HR = 1.19, 95% CI = 0.86–1.64). Moreover, Negative E-cadherin expression was distinctly associated with FIGO stage (OR = 0.42, 95% CI = 0.31–0.57), tumor grade (OR = 0.48, 95% CI = 0.34–0.67), metastasis (OR = 0.13, 95% CI = 0.07–0.26) and recurrence (OR = 0.48, 95% CI = 0.29–0.79). This meta-analysis revealed that negative E-cadherin expression might be a predicative factor of poor prognosis in ovarian cancer patients.

Antimetastatic effects of cordycepin mediated by the inhibition of mitochondrial activity and estrogen-related receptor α in human ovarian carcinoma cells

Cordycepin (3'-deoxyadenosine) is a compound for antitumor, which has been found to exert antiangiogenic, antimetastatic, and antiproliferative effects, as well as inducing apoptosis. However, the association between cancer metastasis and mitochondrial activity in cordycepin-treated ovarian carcinoma cells remains unclear. The 50 and 100 μM of cordycepin inhibits mitochondrial fusion and induces mitochondrial fission, respectively. These suggested that cordycepin showed the down-regulation of mitochondrial function and limitation of energy production. Because of activation of mitochondria and generation of energy are needed in cancer cell migration/invasion. After 24 h treatment, cordycepin suppresses epithelial-mesenchymal transition and migration in ovarian carcinoma cells through inhibiting estrogen-related receptor (ERR)-α. The ERRα is a co-transcription factor for gene expressions associated with mitochondrial fusion. Our results indicate that cordycepin suppresses metastasis and migration of ovarian carcinoma cells via inhibiting mitochondrial activity in non-toxic concentrations, and cordycepin has potential benefits in ovarian cancer therapy.

Integrative proteomic profiling of ovarian cancer cell lines reveals precursor cell associated proteins and functional status

A cell line representative of human high-grade serous ovarian cancer (HGSOC) should not only resemble its tumour of origin at the molecular level, but also demonstrate functional utility in pre-clinical investigations. Here, we report the integrated proteomic analysis of 26 ovarian cancer cell lines, HGSOC tumours, immortalized ovarian surface epithelial cells and fallopian tube epithelial cells via a single-run mass spectrometric workflow. The in-depth quantification of >10,000 proteins results in three distinct cell line categories: epithelial (group I), clear cell (group II) and mesenchymal (group III). We identify a 67-protein cell line signature, which separates our entire proteomic data set, as well as a confirmatory publicly available CPTAC/TCGA tumour proteome data set, into a predominantly epithelial and mesenchymal HGSOC tumour cluster. This proteomics-based epithelial/mesenchymal stratification of cell lines and human tumours indicates a possible origin of HGSOC either from the fallopian tube or from the ovarian surface epithelium.

High-grade serous ovarian cancer is the most common and aggressive ovarian cancer, with uncertain cell of origin. Here, the authors undertake a mass spectrometric analysis of 26 cancer cell lines and identify a protein signature that classifies ovarian cancer tissues into epithelial and mesenchymal groups.

Guidance of Signaling Activations by Cadherins and Integrins in Epithelial Ovarian Cancer Cells

Epithelial ovarian cancer (EOC) is the deadliest tumor among gynecological cancer in the industrialized countries. The EOC incidence and mortality have remained unchanged over the last 30 years, despite the progress in diagnosis and treatment. In order to develop novel and more effective therapeutic approaches, the molecular mechanisms involved in EOC progression have been thoroughly investigated in the last few decades. At the late stage, peritoneal metastases originate from the attachment of small clusters of cancer cells that shed from the primary site and carried by the ascites adhere to the abdominal peritoneum or omentum. This behavior suggests that cell–cell or cell–matrix adhesion mechanisms regulate EOC growth and dissemination. Complex downstream signalings, which might be influenced by functional cross-talk between adhesion molecules and co-expressed and activated signaling proteins, can affect the proliferation/survival and the migration/invasion of EOC cells. This review aimed to define the impact of the mechanisms of cell–cell, through cadherins, and cell–extracellular matrix adhesion, through integrins, on the signaling cascades induced by membrane receptors and cytoplasmic proteins known to have a role in the proliferation, migration and invasion of EOC cells. Finally, some novel approaches using peptidomimetic ligands to cadherin and integrins are summarized.

Aqueous Extract of Paris polyphylla (AEPP) Inhibits Ovarian Cancer via Suppression of Peroxisome Proliferator-Activated Receptor-Gamma Coactivator (PGC)-1alpha

Chemotherapy, a major approach was used in carcinoma treatment, always involves the development of drug resistance as well as side-effects that affect the quality of patients’ lives. An association between epithelial-mesenchymal transition (EMT) and chemotherapy resistance was established recently. We demonstrate in this paper that the aqueous extract of Paris polyphylla (AEPP)—a traditional Chinese medicine—can be used in various cancer types for suppression of carcinogenesis. We evaluated the suppressions of EMT and mitochondrial activity by AEPP treatment in a high-glucose (HG) induced-human ovarian carcinoma cell line (OVCAR-3 cells). The mitochondrial morphology was investigated using MitoTracker Deep Red FM staining. Our results indicated that AEPP reduced the viability of OVCAR-3 cells considerably through induction of apoptosis. However, this inhibitory potential of AEPP was attenuated by HG induction in OVCAR-3 cells. The levels of estrogen-related receptor (ERR)-alpha activator and peroxisome proliferator-activated receptor-gamma coactivator (PGC)-1alpha were elevated by HG induction, but were suppressed by AEPP treatment. Down-regulations of cell survival and EMT were oberved in OVCAR-3 cells through suppression of PGC-1alpha by AEPP treatment. These results were confirmed through PGC-1alpha knockdown and overexpression in OVCAR-3 cells. Thus, AEPP can be beneficial for treating ovarian cancer and has potential for development of an integrative cancer therapy against ovarian cancer proliferation, metastasis, and migration.

Plakoglobin Reduces the in vitro Growth, Migration and Invasion of Ovarian Cancer Cells Expressing N-Cadherin and Mutant p53

Aberrant expression of cadherins and catenins plays pivotal roles in ovarian cancer development and progression. Plakoglobin (PG, γ-catenin) is a paralog of β-catenin with dual adhesive and signaling functions. While β-catenin has known oncogenic function, PG generally acts as a tumor/metastasis suppressor. We recently showed that PG interacted with p53 and that its growth/metastasis inhibitory function may be mediated by this interaction. Very little is known about the role of PG in ovarian cancer. Here, we investigated the in vitro tumor/metastasis suppressor effects of PG in ovarian cancer cell lines with mutant p53 expression and different cadherin profiles. We showed that the N-cadherin expressing and E-cadherin and PG deficient ES-2 cells were highly migratory and invasive, whereas OV-90 cells that express E-cadherin, PG and very little/no N-cadherin were not. Exogenous expression of PG or E-cadherin or N-cadherin knockdown in ES-2 cells (ES-2-E-cad, ES-2-PG and ES-2-shN-cad) significantly reduced their migration and invasion. Also, PG expression or N-cadherin knockdown significantly decreased ES-2 cells growth. Furthermore, PG interacted with both cadherins and with wild type and mutant p53 in normal ovarian and ES-2-PG cell lines, respectively.

Anti-Cancer Activity of Solanum nigrum (AESN) through Suppression of Mitochondrial Function and Epithelial-Mesenchymal Transition (EMT) in Breast Cancer Cells

Chemotherapy is the main approach for treating advanced and recurrent carcinoma, but the clinical performance of chemotherapy is limited by relatively low response rates, drug resistance, and adverse effects that severely affect the quality of life of patients. An association between epithelial-mesenchymal transition (EMT) and chemotherapy resistance has been investigated in recent studies. Our recent studies have found that the aqueous extract of Solanum nigrum (AESN) is a crucial ingredient in some traditional Chinese medicine formulas for treating various types of cancer patients and exhibits antitumor effects. We evaluated the suppression of EMT in MCF-7 breast cancer cells treated with AESN. The mitochondrial morphology was investigated using Mitotracker Deep-Red FM stain. Our results indicated that AESN markedly inhibited cell viability of MCF-7 breast cancer cells through apoptosis induction and cell cycle arrest mediated by activation of caspase-3 and production of reactive oxygen species. Furthermore, mitochondrial fission was observed in MCF-7 breast cancer cells treated with AESN. In addition to elevation of E-cadherin, downregulations of ZEB1, N-cadherin, and vimentin were found in AESN-treated MCF-7 breast cancer cells. These results suggested that AESN could inhibit EMT of MCF-7 breast cancer cells mediated by attenuation of mitochondrial function. AESN could be potentially beneficial in treating breast cancer cells, and may be of interest for future studies in developing integrative cancer therapy against proliferation, metastasis, and migration of breast cancer cells.

microRNA-181a has a critical role in ovarian cancer progression through the regulation of the epithelial-mesenchymal transition

Ovarian cancer is a leading cause of cancer deaths among women. Effective targets to treat advanced epithelial ovarian cancer (EOC) and biomarkers to predict treatment response are still lacking because of the complexity of pathways involved in ovarian cancer progression. Here we show that miR-181a promotes TGF-β-mediated epithelial-to-mesenchymal transition via repression of its functional target, Smad7. miR-181a and phosphorylated Smad2 are enriched in recurrent compared with matched-primary ovarian tumours and their expression is associated with shorter time to recurrence and poor outcome in patients with EOC. Furthermore, ectopic expression of miR-181a results in increased cellular survival, migration, invasion, drug resistance and in vivo tumour burden and dissemination. In contrast, miR-181a inhibition via decoy vector suppression and Smad7 re-expression results in significant reversion of these phenotypes. Combined, our findings highlight an unappreciated role for miR-181a, Smad7, and the TGF-β signalling pathway in high-grade serous ovarian cancer.

Ovarian cancer is often diagnosed at a late stage when metastasis has already occurred. In this study, Parikh et al. show that mir-181a is involved in mediating the epithelial-to-mesenchymal transition in ovarian cancer, leading to activation of the TGF-β signalling pathway and metastasis.

DYRK2 regulates epithelial-mesenchymal-transition and chemosensitivity through Snail degradation in ovarian serous adenocarcinoma

Epithelial-mesenchymal-transition (EMT) plays essential roles in ovarian cancer invasion, metastasis, and drug resistance. A hallmark of EMT is the loss of E-cadherin, which is regulated by Snail. Recently, it was shown that dual-specificity tyrosine-regulated kinase 2 (DYRK2) controls Snail degradation in breast cancer. The aim of this study is to clarify whether DYRK2 regulates EMT through Snail degradation in ovarian serous adenocarcinoma (SA). Expression of DYRK2 and Snail in two pairs of cisplatin-resistant and the original cisplatin-sensitive ovarian cancer cell line were analyzed by immunoblotting and real-time RT-PCR analysis. Morphological change, invasion ability, and chemosensitivity were evaluated by using DYRK2 stable knockdown cell line in 2008 (2008 shDYRK2). Immunohistochemical analyses for DYRK2 and Snail were performed with surgical specimens. The correlations between the expression of these proteins and the clinicopathological parameters, including prognosis, were determined. Moreover, we conducted a hypodermic administration test in nude mice and examined reproductive and cisplatin response activities. DYRK2 protein expression was posttranslationally reduced in cisplatin-resistant SA cell lines. 2008 shDYRK2 showed mesenchymal phenotype and resistant to cisplatin. Immunohistochemistry demonstrated that DYRK2 expression inversely correlated with Snail expression, and reduced expression of DYRK2 was associated with shorter overall survival in SA. DYRK2 may regulate EMT through Snail degradation in ovarian SA and might be a predictive marker for a favorable prognosis in the treatment of this cancer.

OCT4 mediates FSH-induced epithelial-mesenchymal transition and invasion through the ERK1/2 signaling pathway in epithelial ovarian cancer

Our previous study showed that Octamer-binding transcription factor 4 (OCT4) expression was upregulated and significantly associated with histological grade through the analysis of OCT4 expression in 159 ovarian cancer tissue samples, and OCT4 mediated follicle-stimulating hormone (FSH)-induced anti-apoptosis in epithelial ovarian cancer. Nevertheless, whether OCT4 participates in FSH-induced invasion in ovarian cancer is still unknown. Therefore, the present study aimed to define whether FSH-induced ovarian cancer invasion is mediated by OCT4. In present study, we showed that FSH induced not only the epithelial-mesenchymal transition (EMT) and invasive phenotype but also the upregulation of OCT4 expression in a dose- and time-dependent manner in epithelial ovarian cancer cells. In addition, the expression of FSH receptor (FSHR) was upregulated by FSH induction, and knockdown of FSHR inhibited FSH-stimulated OCT4 expression. ERK1/2 signaling pathway participated in the enhanced expression of OCT4 and Snail induced by FSH. We further showed that the activated expression of Snail and N-cadherin, the suppressed expression of E-cadherin and the morphological change of the cells stimulated by FSH were blocked by OCT4-specific small interfering RNA. Moreover, our results showed that OCT4 mediated the increase in invasive capacity induced by FSH in ovarian cancer cells. Taken together, our work reveals that OCT4 is an essential mediator in FSH-induced EMT and invasion in epithelial ovarian cancer and may act as a potential therapeutic target.

Specimen quality evaluation in Canadian biobanks participating in the COEUR repository

Human biological specimens are important for translational research programs such as the Canadian Ovarian Experimental Unified Resource (COEUR) funded by the Terry Fox Research Institute. Sample quality is an important consideration, as it directly impacts the quality of ensuing research. The aim of the present study was to determine the quality of tissues collected from different sites contributing to the COEUR cohort. Samples from high-grade serous ovarian tumors (fresh frozen and corresponding paraffin-embedded tissues) were provided by nine participating Canadian biobanks. All samples were shipped to a central site using a Standard Operating Protocol (SOP). DNA and RNA extraction was conducted by the quality control division of the Canadian Tumor Repository Network (CTRNet). DNA quality was determined by ß-globin gene PCR amplification, and RNA quality by the RNA integrity number (RIN), as measured by the Agilent BioAnalyzer. DNA of acceptable quality had at least three bands of ß-globin amplified from DNA (n=115/135), and a RIN number ≥7 was considered very good for RNA (n=80/135). Sample preparation and storage time had little effect on RNA or DNA quality. Protein expression was assessed on tissue microarray by immunohistochemistry with antibodies against p53, WT1, E-cadherin, CK-7, and Ki67 from formalin fixed-paraffin embedded (FFPE) tissues. As seen with a nonhierarchical clustering statistical method, there was no significant difference in immunostaining of paraffin tissues among specimens from different biobanks. Interestingly, patients with worse outcome were highly positive for p53 and weak for WT1. In conclusion, while there was no common SOP for retrospectively collected material across Canadian biobanks, these results indicate that specimens collected at these multiple sites are of comparable quality, and can serve as an adequate resource to create a national cohort for the validation of molecular biomarkers in ovarian cancer.

Prognostic significance of single isolated cells with decreased E-cadherin expression in pseudomyxoma peritonei

Pseudomyxoma peritonei (PMP) cases can be classified into the prognosis-related subtypes of disseminated peritoneal adenomucinosis (DPAM) and peritoneal mucinous carcinomatosis (PMCA). To investigate the mechanisms of mucinous invasion and the differing prognoses of these two subtypes, we examined the expression levels of proteins involved in cellular adhesion and invasion, including E-cadherin, vimentin, β-catenin, and S100A4, in single isolated tumor cells (SICs) and cohesive cellular strips within mucin pools isolated from DPAM (n = 31) and PMCA (n = 21) patients. In both PMCA and DPAM cases, SICs showed a complete loss of E-cadherin expression, whereas cells in cohesive cellular clusters retained E-cadherin expression. The frequency of high numbers of SICs (>8) in PMCA cases was significantly greater than that in DPAM cases (86% and 26%, respectively) and was correlated with poor progression-free survival (P = 0.019) in a univariate analysis. In both PMP subtypes, strong vimentin expression was identified in most of the SICs but not the cohesive cellular strips. The relatively slow progression of DPAM may be attributable to the smaller number of SICs that lack E-cadherin expression and have increased vimentin expression, whereas the rapid progression of PMCA may be due to larger numbers of these SICs.

GAGE12 mediates human gastric carcinoma growth and metastasis

The spontaneous metastasis from human gastric carcinoma (GC) remains poorly reproduced in animal models. Here, we established an experimental mouse model in which GC progressively developed in the orthotopic stomach wall and metastasized to multiple organs; the tumors colonized in the ovary exhibited typical characteristics of Krukenberg tumor. The expression of mesenchymal markers was low in primary tumors and high in those in intravasating and extravasating veins. However, the expression of epithelial markers did not differ, indicating that the acquisition of mesenchymal markers without a concordant loss of typical epithelial markers was associated with metastasis. We identified 35 differentially expressed genes (DEGs) in GC cells metastasized to ovary, among which overexpression of GAGE12 family genes, the top-ranked DEGs, were validated. In addition, knockdown of the GAGE12 gene family affected transcription of many of the aforementioned 35 DEGs and inhibited trans-well migration, tumor sphere formation in vitro and tumor growth in vivo. In accordance, GAGE12 overexpression augmented migration, tumor sphere formation and sustained in vivo tumor growth. Taken together, the GAGE12 gene family promotes GC growth and metastasis by modulating the expression of GC metastasis-related genes.

Loss of N-cadherin is associated with loss of E-cadherin expression and poor outcomes of liver resection in hepatocellular carcinoma

BACKGROUND

Our previous study suggested that N-cadherin was downregulated in hepatocellular carcinoma (HCC). Our aim in this study was to investigate the correlation between N- and E-cadherin expression in HCC and its clinical significance.

METHODS

Eighty-six patients with HCC undergoing liver resection were retrospectively studied. N- and E-cadherin expression in HCC and adjacent liver tissue were investigated using immunohistochemistry and immunofluorescence. The correlation between the expression status of both cadherins and surgical outcomes was analyzed.

RESULTS

In 23 patients negative for E-cadherin expression, 19 of them (82.6%) were also negative for N-cadherin expression. In 30 patients with heterogeneous expression of E-cadherin, 20 of them (66.7%) also had heterogeneous expression of N-cadherin. In 33 patients with uniformly positive expression of E-cadherin, 19 of them (57.6%) also had uniformly positive expression of N-cadherin. Therefore, there was a positive correlation between expression patterns of N- and E-cadherins. Concurrent loss of both N- and E-cadherin expressions was significantly associated with absence of the tumor capsule, vascular invasion, and poor differentiation. The 1- and 3-y disease-free survival rates were 27% and 9%, respectively, and the 1- and 3-y overall survival rates were 64.3% and 14.3%, respectively, in patients with concurrent loss of both cadherins, which were significantly worse than those with concurrent uniformly positive expression or heterogeneous expression of both cadherins.

CONCLUSIONS

Loss of N-cadherin was positively correlated with loss of E-cadherin in HCC. Concurrent loss of both N- and E-cadherin expressions was associated with poor surgical outcomes of HCC patients undergoing liver resection.

Correlation Between E-cadherin Immunoexpression and Efficacy of First Line Platinum-Based Chemotherapy in Advanced High Grade Serous Ovarian Cancer

To analyze correlation between immunoexpression of E-cadherin and efficacy of first line platinum-based chemotherapy in patients with advanced-stage high-grade serous ovarian carcinoma. The expression of E-cadherin was analyzed immunohistochemically in formalin-fixed, paraffin-embedded samples from 98 patients with advanced-stage high-grade serous ovarian cancer and related to clinical features (stage according to the International Federation of Gynecology and Obstetrics (FIGO) and residual tumors after initial cytoreductive surgery), response to platinum-based chemotherapy (according to Response Evaluation Criteria in Solid tumors (RECIST 1.1 criteria)), platinum sensitivity (according to platinum free interval (PFI) as platinum-refractory, platinum-resistant and platinum-sensitive) and patients progression free survival (PFS) and overall survival (OS). E-cadherin immunostaining was positive in 74 and negative in 24 serous ovarian carcinomas. E-cadherin immunoreactivity was not associated with FIGO stage, residual tumor after initial cytoreductive surgery and number of chemotherapy cycles. Positive E-cadherin expression predict significantly better response to first line platinum-based chemotherapy (p < 0.001) and platinum sensitivity (p < 0.001). Moreover, positive E-cadherin expression predict significantly longer PFS (p < 0.001) and OS (p < 0.001). The multivariate analysis for OS showed that positive E-cadherin expression is predictor to platinum sensitivity (p < 0.001) and longer OS (p = 0.01). Positive E-cadherin expression seems to be a predictor of better response to first line platinum-based chemotherapy, platinum sensitivity and favorable clinical outcome in patients with advanced-stage serous ovarian cancer. Negative E-cadherin expression was shown to be significant, independent predictor of poorer PFS and OS. E-cadherin as a marker has predictive and prognostic value.

Expression and significance of twist and E-cadherin in ovarian cancer tissues

OBJECTIVE

To investigate the expression of Twist and E-cadherin in ovarian cancer tissues as well as the role of epithelial-mesenchymal transformation (EMT) in ovarian cancer metastasis.

METHOD

The expressions of Twist and E-cadherin in 54 cases of ovarian cancer and paracancerous tissues were detected by Western blottin g and reverse transcriptase polymerase chain reaction. We used RNA interference to silence Twist expression in human ovarian cancer cell line, and detected E-cadherin expression using Western blotting.

RESULTS

There was an increase in the relative abundance of Twist proteins and a decrease in E-cadherin in ovarian cancer compared with normal ovary tissues (P < 0.05). The expression levels of Twist and E-cadherin mRNA were 1.49 ± 0.53 and 0.82 ± 0.24 in ovarian cancer, and 1.14 ± 0.38 and 1.08 ± 0.19 in paracancerous tissues, respectively. The difference between the indicators in ovarian cancer and in paracancerous tissues was statistically significant (P < 0.05). When the Twist expression was silenced in an ovarian cancer cell line, the expression of the E-cadherin protein increased (P<0.05).

CONCLUSION

The expression of Twist is upregulated, whereas that of E-cadherin is downregulated in ovarian cancer. EMT, mediated by Twist, may be correlated with ovarian cancer metastasis.

Construction and characteristics of an E-cadherin-related three-dimensional suspension growth model of ovarian cancer

Ovarian cancer is the deadliest of all gynecologic malignancies. Metastatic ovarian cancer cells exist mainly in the form of multi-cellular spheroids (MCSs) in the ascites of patients with advanced ovarian cancer. We hypothesized that E-cadherin, as an important cell-adhesion molecule, might play an important role in the formation and survival of MCSs. Therefore, we established a three-dimensional suspension culture model of ovarian cancer cells that express high levels of E-cadherin to investigate their growth, proliferation, and resistance to chemotherapeutic drugs by CCK-8 assays. Compared to the cell suspension masses formed by cells with low or absent E-cadherin expression, the MCSs of high E-cadherin SKOV-3 cells had larger volumes, tighter cellular connections, and longer survival times. Although the suspension cell masses of all three cell lines were proliferatively stagnant, possibly due to cell cycle arrest at G1/S, cell mortality at 72 h after cisplatin treatment was significantly decreased in the high E-cadherin SKOV-3 cells compared to SKOV-3 cells without E-cadherin expression and to OVCAR-3 cells with low E-cadherin expression. We conclude, therefore, E-cadherin plays a vital role in MCS formation, maintenance, and drug resistance in ovarian cancer and could be a potential target for late-stage ovarian cancer treatment.

Loss of E-cadherin promotes migration and invasion of cholangiocarcinoma cells and serves as a potential marker of metastasis

Tumor progression is characterized by loss of cell adhesion and increase of invasion and metastasis. E-cadherin, a cell adhesion molecule, is frequently downregulated and has been proposed as an important mediator in epithelial-mesenchymal transition (EMT) in tumors. In this study, we investigated the expression of E-cadherin and its association with cancer invasion and prognosis in cholangiocarcinoma (CCA). Immunohistochemistry results demonstrated a statistically significant association between the positive metastasis status with low E-cadherin protein expression in human CCA tissues (P = 0.04). Statistical trends were identified for low E-cadherin level and shorter survival time (P = 0.08). Targeting the E-cadherin expression in CCA cells with siRNA caused upregulation of vimentin, a mesenchymal marker, and disappearance of the E-cadherin/β-catenin adhesion complex from cell membranes. Moreover, migration and invasion abilities of the cells were increased under this condition. These findings suggest that reduction of E-cadherin contributes to CCA progression by attenuating the strength of cellular adhesion, which affects motility as well as regulating the expression of EMT-related genes during CCA invasion and metastasis. Thus, E-cadherin can act as a central modulator of tumor cell phenotype and is a potential metastasis marker in CCA.

FGF16 promotes invasive behavior of SKOV-3 ovarian cancer cells through activation of mitogen-activated protein kinase (MAPK) signaling pathway

Uncontrolled cell growth and tissue invasion define the characteristic features of cancer. Several growth factors regulate these processes by inducing specific signaling pathways. We show that FGF16, a novel factor, is expressed in human ovary, and its expression is markedly increased in ovarian tumors. This finding indicated possible involvement of FGF16 in ovarian cancer progression. We observed that FGF16 stimulates the proliferation of human ovarian adenocarcinoma cells, SKOV-3 and OAW-42. Furthermore, through the activation of FGF receptor-mediated intracellular MAPK pathway, FGF16 regulates the expression of MMP2, MMP9, SNAI1, and CDH1 and thus facilitates cellular invasion. Inhibition of FGFR as well as MAPK pathway reduces the proliferative and invasive behavior of ovarian cancer cells. Moreover, ovarian tumors with up-regulated PITX2 expression also showed activation of Wnt/β-catenin pathway that prompted us to investigate possible interaction among FGF16, PITX2, and Wnt pathway. We identified that PITX2 homeodomain transcription factor interacts with and regulates FGF16 expression. Furthermore, activation of the Wnt/β-catenin pathway induces FGF16 expression. Moreover, FGF16 promoter possesses the binding elements of PITX2 as well as T-cell factor (Wnt-responsive), in close proximity, where PITX2 and β-catenin binds to and synergistically activates the same. A detail study showed that both PITX2 and T-cell factor elements and the interaction with their binding partners are necessary for target gene expression. Taken together, our findings indicate that FGF16 in conjunction with Wnt pathway contributes to the cancer phenotype of ovarian cells and suggests that modulation of its expression in ovarian cells might be a promising therapeutic strategy for the treatment of invasive ovarian cancers.

Thrombomodulin mediates the migration of cervical cancer cells through the regulation of epithelial-mesenchymal transition biomarkers

Thrombomodulin (TM) has been shown to regulate many physiological and pathological processes, including inflammation, thrombosis, and tumor progression. TM is also a natural anticoagulant that maintains circulatory homeostasis in endothelial cells. However, little is known regarding the role of TM in the progression and metastasis of cervical cancer. TM-specific RNA interference and a cDNA expression vector were used to manipulate TM expression in cervical cancer cells. Cell growth and cell migration were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, transwell migration assays, and a biosensor system. TM silencing did not affect the growth rate of the cells. However, cell migration was dramatically enhanced after silencing of TM in HeLa cells. The overexpression of TM in cervical cancer cells only slightly influenced their proliferative capacity. After overexpression of TM in HeLa cells, their migratory capability was suppressed. Furthermore, we found that the decreased expression of E-cadherin and increase of zeb-1 and snail expression in TM-silenced cells which may be correlated with the results of knocking-down TM increases the migratory ability in this study. Our results demonstrate that TM may slightly regulate the growth but played the important role in the migratory ability of cervical cancer cells, suggesting that TM could potentially serve as a novel prognostic and therapeutic target in cervical cancer.

Fibroblast growth factor 2 induces E-cadherin down-regulation via PI3K/Akt/mTOR and MAPK/ERK signaling in ovarian cancer cells

Fibroblast growth factor 2 (FGF2) is produced by ovarian cancer cells and it has been suggested to play an important role in tumor progression. In this study, we report that FGF2 treatment down-regulated E-cadherin by up-regulating its transcriptional repressors, Slug and ZEB1, in human ovarian cancer cells. The pharmacological inhibition of phosphatidylinositol-3-kinase (PI3K), mammalian target of rapamycin (mTOR), and MEK suggests that both PI3K/Akt/mTOR and MAPK/ERK signaling are required for FGF2-induced E-cadherin down-regulation. Moreover, FGF2 up-regulated Slug and ZEB1 expression via the PI3K/Akt/mTOR and MAPK/ERK signaling pathways, respectively. Finally, FGF2-induced cell invasion was abolished by the inhibition of the PI3K/Akt/mTOR and MAPK/ERK pathways, and the forced expression of E-cadherin diminished the intrinsic invasiveness of ovarian cancer cells as well as the FGF2-induced cell invasion. This study demonstrates a novel mechanism in which FGF2 down-regulates E-cadherin expression through the activation of PI3K/Akt/mTOR and MAPK/ERK signaling, and the up-regulation of Slug and ZEB1 in human ovarian cancer cells.

Prognostic role of E-cadherin in patients with advanced serous ovarian cancer

PURPOSE

To analyse correlation between expression of E-cadherin and clinical and pathological features and overall survival in advanced-stage serous ovarian carcinoma.

METHODS

The expression of E-cadherin was analysed immunohistochemically in formalin-fixed, paraffin-embedded samples from 54 patients with advanced-stage serous ovarian cancer and related to clinicopathological characteristics and patients survival. The clinicopathological characteristics included the stage according to the International Federation of Gynecology and Obstetrics (FIGO), tumour differentiation, number of mitoses per 10 high-power fields (HPF), residual tumour size, and vascular invasion. Only patients with serous ovarian cancer FIGO stages III-IV were included. Overall survival (OS) was defined as time from surgery to the last follow-up date on 01.10.2010. OS was evaluated using Kaplan-Meier method, and log-rank test was used to asses the differences between the positive and E-cadherin negative group. Multivariate analysis was completed using the Cox proportional hazard regression model.

RESULTS

E-cadherin immunoreactivity was not associated with FIGO stage, tumour grade, number of mitotic figures per 10 HPF, residual tumour volume or vascular invasion. Negative E-cadherin expression significantly predicted shorter OS (p < 0.001). The multivariate analyses showed that negative E-cadherin (p < 0.001), FIGO stage (p = 0.012) and residual tumour size >1 cm after the initial cytoreductive surgery (p < 0.001) were predictors of shorter OS.

CONCLUSION

Negative E-cadherin expression like presence of residual tumour after primary cytoreductive surgery and higher FIGO stage seem to predict unfavourable clinical outcome in patients with advanced-stage serous ovarian cancer. Negative expression of E-cadherin was shown to be a significant independent predictor of poorer OS. E-cadherin as marker has prognostic value.

Hypoxia-inducible factor 1 alpha mediates epidermal growth factor-induced down-regulation of E-cadherin expression and cell invasion in human ovarian cancer cells

Hypoxia-inducible factor 1α (HIF-1α) regulates the transcription of a number of genes under hypoxia and other extracellular stimulations. It has been shown that E-cadherin is down-regulated by epidermal growth factor receptor (EGF) stimulation, and that cells with low E-cadherin expression are more invasive. Our recent study demonstrated a novel mechanism by which EGF down-regulates E-cadherin expression through production of hydrogen peroxide (H(2)O(2)) and the activation of p38 MAPK in human ovarian cancer cells. In this study, we were interested in examining the potential role of HIF-1α in cell invasion under normoxic conditions, specifically when cells are treated with EGF, which is known to down-regulate E-cadherin and increase invasiveness. We show that EGF treatment induces HIF-1α expression in two human ovarian cancer cell lines (SKOV3 and OVCAR5), and that this effect is diminished by treatment with a membrane-permeable H(2)O(2) scavenger, PEG-catalase. However, the induction of HIF-1α by EGF did not require the activation of p38 MAPK. Treatment with siRNA targeting HIF-1α reduces both basal and EGF-induced HIF-1α levels. Importantly, treatment with HIF-1α siRNA diminishes the up-regulation of Snail and Slug as well as the down-regulation of E-cadherin by EGF. The involvement of HIF-1α in the down-regulation of E-cadherin was confirmed with cobalt chloride (CoCl(2)), a hypoxia-mimetic reagent. Finally, we also show that EGF-induced cell invasion is attenuated by treatment with HIF-1α siRNA. This study demonstrates an important role for HIF-1α in mediating the effects of EGF on Snail, Slug and E-cadherin expression as well as invasiveness in human ovarian cancer cells.

Paradoxical impact of two folate receptors, FRα and RFC, in ovarian cancer: effect on cell proliferation, invasion and clinical outcome

Despite being an essential vitamin, folate has been implicated to enhance tumor growth, as evidenced by reports on overexpression of folate receptor alpha (FRα) in carcinomas. The role of another folate transporter, reduced folate carrier (RFC), is largely unknown. This study investigated the roles of folate, FRα and RFC in ovarian cancers. We demonstrated FRα mRNA and protein overexpression and reduced RFC expression in association with FRα gene amplification and RFC promoter hypermethylation, respectively. FRα overexpression was associated with tumor progression while RFC expression incurred a favorable clinical outcome. Such reciprocal expression pattern was also observed in ovarian cancer cell lines. Folate was shown to promote cancer cell proliferation, migration and invasion in vitro, and down-regulate E-cadherin expression. This effect was blocked after either stable knockdown of FRα or ectopic overexpression of RFC. This hitherto unreported phenomenon suggests that, RFC can serve as a balancing partner of FRα and confer a protective effect in patients with high FRα-expressing ovarian carcinomas, as evidenced by their prolonged overall and disease-free survivals. In conclusion, we report on the paradoxical impact of FRα (putative oncogenic) and RFC (putative tumor suppressive) in human malignancies. FRα and RFC may potentially be explored as therapeutic target or prognostic marker respectively. We recommend caution and additional research on folate supplements in cancer patients.

N-cadherin Expression in Testicular Germ Cell and Gonadal Stromal Tumors

Neural-cadherin is a member of the cadherin gene family encoding the N-cadherin protein that mediates cell adhesion. N-cadherin is a marker of Sertoli cells and is also expressed in germ cells of varying stages of maturation. The purpose of this study was to determine the presence and distribution of this protein by immunohistochemistry in 105 germ cell tumors of both single and mixed histological types and 12 gonadal stromal tumors. Twenty-four germ cell tumors consisted of one cell type and the remaining were mixed. Of the 23 seminomas in either pure or mixed tumors, 74% were positive. Two spermatocytic seminomas were positive. Of the 83 cases with yolk sac tumor, 99% were positive for N-cadherin. The teratomas were positive in 73% in neuroectodermal and / or glandular components. In contrast, 87% of embryonal carcinomas did not express N-cadherin. Only 17% of the syncytiotrophoblastic cells were positive for N-cadherin. In conclusion, N-cadherin expression is very helpful in the identification of yolk sac tumors. In addition to glypican-3 and Sal-like protein 4, N-cadherin can be beneficial for the diagnosis and classification of this subtype of testicular germ cell tumor. Nine of the 12 gonadal stromal tumors were positive to a variable extent.

Stem cell transcription factor NANOG controls cell migration and invasion via dysregulation of E-cadherin and FoxJ1 and contributes to adverse clinical outcome in ovarian cancers

Ovarian cancer is the most lethal of all gynecological malignancies, and the identification of novel prognostic and therapeutic targets for ovarian cancer is crucial. It is believed that only a small subset of cancer cells are endowed with stem cell properties, which are responsible for tumor growth, metastatic progression and recurrence. NANOG is one of the key transcription factors essential for maintaining self-renewal and pluripotency in stem cells. This study investigated the role of NANOG in ovarian carcinogenesis and showed overexpression of NANOG mRNA and protein in the nucleus of ovarian cancers compared with benign ovarian lesions. Increased nuclear NANOG expression was significantly associated with high-grade cancers, serous histological subtypes, reduced chemosensitivity, and poor overall and disease-free survival. Further analysis showed NANOG is an independent prognostic factor for overall and disease-free survival. Moreover, NANOG was highly expressed in ovarian cancer cell lines with metastasis-associated property and in clinical samples of metastatic foci. Stable knockdown of NANOG impeded ovarian cancer cell proliferation, migration and invasion, which was accompanied by an increase in mRNA expression of E-cadherin, caveolin-1, FOXO1, FOXO3a, FOXJ1 and FOXB1. Conversely, ectopic NANOG overexpression enhanced ovarian cancer cell migration and invasion along with decreased E-cadherin, caveolin-1, FOXO1, FOXO3a, FOXJ1 and FOXB1 mRNA expression. Importantly, we found Nanog-mediated cell migration and invasion involved its regulation of E-cadherin and FOXJ1. This is the first report revealing the association between NANOG expression and clinical outcome of patients with ovarian cancers, suggesting NANOG to be a potential prognostic marker and therapeutic molecular target in ovarian cancer.

The PI3K/Akt/mTOR signaling pathway mediates insulin-like growth factor 1-induced E-cadherin down-regulation and cell proliferation in ovarian cancer cells

Insulin-like growth factor 1 (IGF1) is produced by ovarian cancer cells and it has been suggested that it plays an important role in tumor progression. In this study, we report that IGF1 treatment down-regulated E-cadherin by up-regulating E-cadherin transcriptional repressors, Snail and Slug, in human ovarian cancer cells. The pharmacological inhibition of phosphatidylinositol-3-kinase (PI3K) and mammalian target of rapamycin (mTOR) suggests that PI3K/Akt/mTOR signaling is required for IGF1-induced E-cadherin down-regulation. Moreover, IGF1 up-regulated Snail and Slug expression via the PI3K/Akt/mTOR signaling pathway. Finally, IGF1-induced cell proliferation was abolished by inhibiting PI3K/Akt/mTOR signaling. This study demonstrates a novel mechanism in which IGF1 down-regulates E-cadherin expression through the activation of PI3K/Akt/mTOR signaling and the up-regulation of Snail and Slug in human ovarian cancer cells.

E-cadherin promotes proliferation of human ovarian cancer cells in vitro via activating MEK/ERK pathway

AIM

E-cadherin is unusually highly expressed in most ovarian cancers. This study was designed to investigate the roles of E-cadherin in the carcinogenesis and progression of ovarian cancers.

METHODS

Human ovarian adenocarcinoma cell line SKOV-3 was examined. E-cadherin gene CDH1 in SKOV-3 cells was knocked down via RNA interference (RNAi), and the resultant variation of biological behavior was observed using CCK-8 and colony formation experiment. E-cadherin-mediated Ca(2+)-dependent cell-cell adhesion was used to study the mechanisms underlying the effects of E-cadherin on the proliferation and survival of SKOV-3 cells. The expression levels of E-cadherin, extracellular signal-related kinase (ERK), phosphorylated ERK (P-ERK) were measured using Western blot assays.

RESULTS

Transfection with CDH1-siRNA for 24-96 h significantly suppressed the growth and proliferation of SKOV-3 cells. E-cadherin-mediated calcium-dependent cell-cell adhesion of SKOV-3 cells resulted in a rapid increase of P-ERK, but did not modify the expression of ERK protein. The phosphorylation of ERK in the cells was blocked by pretreatment with the MEK1 specific inhibitor PD98059 (50 μmol/L), but not by the PI3K inhibitor wortmannin (1 μmol/L) or PKA inhibitor H89 (10 μmol/L).

CONCLUSION

E-cadherin may function as a tumor proliferation enhancer via activating the MEK/ERK pathway in development of ovarian epithelial cancers.

Egr-1 mediates epidermal growth factor-induced downregulation of E-cadherin expression via Slug in human ovarian cancer cells

Loss of the cell adhesion protein E-cadherin increases the invasive capability of ovarian cancer cells. We have previously shown that epidermal growth factor (EGF) downregulates E-cadherin and induces ovarian cancer cell invasion through the H(2)O(2)/p38 MAPK-mediated upregulation of the E-cadherin transcriptional repressor Snail. However, the molecular mechanisms underlying the EGF-induced downregulation of E-cadherin are not fully understood. In the current study, we demonstrated that treatment of two ovarian cancer cell lines, SKOV3 and OVCAR5, with EGF induced the expression of the transcription factor Egr-1, and this induction was abolished by small interfering RNA (siRNA)-mediated depletion of the EGF receptor. EGF-induced Egr-1 expression required the activation of the ERK1/2 and PI3K/Akt signaling pathways and was unrelated to EGF-induced H(2)O(2) production and activation of the p38 MAPK pathway. Moreover, depletion of Egr-1 with siRNA abolished the EGF-induced downregulation of E-cadherin and increased cell invasion. Interestingly, siRNA depletion of Egr-1 attenuated the EGF-induced expression of Slug, but not that of Snail. Moreover, chromatin immunoprecipitation (ChIP) analysis showed that Slug is a target gene of Egr-1. These results provide evidence that Egr-1 is a mediator that is involved in the EGF-induced downregulation of E-cadherin and increased cell invasion. Our results also demonstrate that EGF activates two independent signaling pathways, which are the H(2)O(2)/p38 MAPK-mediated upregulation of Snail expression and the Egr-1-mediated upregulation of Slug expression. These two signaling pathways contribute to the EGF-induced downregulation of E-cadherin, which subsequently increases the invasive capability of ovarian cancer cells.

Epithelial-mesenchymal transition in ovarian carcinoma

Ovarian cancer is the most lethal gynecologic malignancy, with the majority of patients dying within 5 years of diagnosis. This poor survival of patients diagnosed with this malignancy is attributed to diagnosis at advanced stage, when the tumor has metastasized, and to chemotherapy resistance, either primary or developing along tumor progression. However, ovarian carcinomas, constituting the vast majority of ovarian cancers, additionally have unique biology, one aspect of which is the ability to co-express epithelial and mesenchymal determinants. epithelial–mesenchymal transition (EMT), a physiological process by which mesenchymal cells are formed and migrate to target organs during embryogenesis, is involved in cancer cell invasion and metastasis. However, these changes do not fully occur in ovarian carcinoma, and are even reversed in tumor cells present in malignant peritoneal and pleural effusions. This review summarizes current knowledge in this area, including the characteristics of EMT related to adhesion, transcriptional regulation and chemoresistance, and their clinical relevance, as well as the recently observed regulation of EMT by microRNA.