E‐cadherin expression increases cell proliferation by regulating energy metabolism through nuclear factor‐κB in AGS cells

β‐Catenin is a central player in Wnt signaling, and activation of Wnt signaling is associated with cancer development. E‐cadherin in complex with β‐catenin mediates cell–cell adhesion, which suppresses β‐catenin‐dependent Wnt signaling. Recently, a tumor‐suppressive role for E‐cadherin has been reconsidered, as re‐expression of E‐cadherin was reported to enhance the metastatic potential of malignant tumors. To explore the role of E‐cadherin, we established an E‐cadherin‐expressing cell line, EC96, from AGS cells that featured undetectable E‐cadherin expression and a high level of Wnt signaling. In EC96 cells, E‐cadherin re‐expression enhanced cell proliferation, although Wnt signaling activity was reduced. Subsequent analysis revealed that nuclear factor‐κB (NF‐κB) activation and consequent c‐myc expression might be involved in E‐cadherin expression‐mediated cell proliferation. To facilitate rapid proliferation, EC96 cells enhance glucose uptake and produce ATP using both mitochondria oxidative phosphorylation and glycolysis, whereas AGS cells use these mechanisms less efficiently. These events appeared to be mediated by NF‐κB activation. Therefore, E‐cadherin re‐expression and subsequent induction of NF‐κB signaling likely enhance energy production and cell proliferation.     

Beyond a tumor suppressor: Soluble E‐cadherin promotes the progression of cancer

E‐cadherin (E‐cad) plays important roles in tumorigenesis as well as in tumor progression, invasion and metastasis. This protein exists in two forms: a membrane‐tethered form and a soluble form. Full‐length E‐cad is membrane tethered. As a type I transmembrane glycoprotein, E‐cad mainly mediates adherens junctions between cells and is involved in maintaining the normal structure of epithelial tissues. Soluble E‐cad (sE‐cad) is the extracellular fragment of the protein that is cleaved from the membrane after proteolysis of full‐length E‐cad. The production of sE‐cad undermines adherens junctions, causing a reduction in cell aggregation capacity; furthermore, sE‐cad can diffuse into the extracellular environment and the blood. As a paracrine/autocrine signaling molecule, sE‐cad activates or inhibits multiple signaling pathways and participates in the progression of various types of cancer, such as breast cancer, ovarian cancer, and lung cancer, by promoting invasion and metastasis. This article briefly reviews the role of sE‐cad in tumorigenesis and tumor progression and its significance in clinical therapeutics.     

Recruited monocytic myeloid‐derived suppressor cells promote the arrest of tumor cells in the premetastatic niche through an IL‐1β‐mediated increase in E‐selectin expression

The tumor premetastatic niche initiated by primary tumors is constructed by multiple molecular factors and cellular components and provides permissive condition that allows circulating tumor cells to successfully metastasize. Myeloid‐derived suppressor cells (MDSCs), a population of immature cells in pathological conditions, play a critical role in the formation of the premetastatic niche. However, few researches are focused on the function of monocytic MDSCs (mo‐MDSCs), a subtype of MDSCs, in the construction of the niche. Here, we show that the number of mo‐MDSCs is significantly increased in the premetastatic lungs of tumor‐bearing mice, thus promoting tumor cell arrest and metastasis. Before the arrival of tumor cells, the lung‐recruited mo‐MDSCs produced IL‐1β, thereby increasing E‐selectin expression and promoting tumor cell arrest on endothelial cells. Depletion of mo‐MDSCs in the premetastatic lungs decreased IL‐1β production, resulting in reduced E‐selectin expression. In addition, compared with alveolar macrophages and interstitial macrophages, mo‐MDSCs were the major source of IL‐1β expression in the premetastatic lungs. Cytokine array analyses and transwell experiments revealed that CCL12 recruits mo‐MDSCs to premetastatic lungs. CCL12 knockdown in tumor‐bearing mice significantly decreased mo‐MDSC infiltration into the premetastatic lungs, leading to reduced E‐selectin expression. Overall, the permissive conditions produced by the infiltrated mo‐MDSCs correlated with increased tumor cell arrest and metastasis. These results reveal a novel role of mo‐MDSCs in constructing the premetastatic niche. Thus, inhibition of mo‐MDSCs infiltration may change the premetastatic niche to normal condition and attenuate tumor metastasis.     

Polycomb group protein EZH2‐mediated E‐cadherin repression promotes metastasis of oral tongue squamous cell carcinoma

Enhancer of Zeste homolog 2 (EZH2) is a critical component of the polycomb‐repressive complex 2 (PRC2) that regulates many essential biological processes, including embryogenesis and many developmental events. The oncogenic role of EZH2 has recently been implicated in several cancer types. In this study, we first confirmed that the over‐expression of EZH2 is a frequent event in oral tongue squamous cell carcinoma (OTSCC). We further demonstrated that EZH2 over‐expression is correlated with advanced stages of the disease and is associated with lymph node metastasis. Statistical analysis revealed that EZH2 over‐expression was correlated with reduced overall survival. Furthermore, over‐expression of EZH2 was correlated with reduced expression of tumor suppressor gene E‐cadherin. These observations were confirmed in vitro, in which knockdown of EZH2‐induced E‐cadherin expression and reduced cell migration and invasion. In contrast, ectopic transfection of EZH2 led to reduced E‐cadherin expression and enhanced cell migration and invasion. Furthermore, EZH2 may act on cell migration in part by suppressing the E‐cadherin expression. Taken together, these data suggest that EZH2 plays major roles in the progression of OTSCC, and may serve as a biomarker or therapeutic target for patients at risk of metastasis. © 2011 Wiley Periodicals, Inc.     

Epidermal growth factor down‐regulates the expression of neutrophil gelatinase‐associated lipocalin (NGAL) through E‐cadherin in pancreatic cancer cells

BACKGROUND:

The authors previously reported that neutrophil gelatinase‐associated lipocalin (NGAL) overexpression significantly blocked invasion and angiogenesis of pancreatic ductal adenocarcinoma (PDAC). They also demonstrated a loss of NGAL expression in the advanced stages of PDAC. However, little is known regarding the mechanisms of NGAL regulation in PDAC. Because the epidermal growth factor (EGF)‐EGF receptor (EGFR) axis is up‐regulated significantly in PDAC, they examined EGF‐mediated NGAL regulation in these cells.

METHODS:

The NGAL‐positive cell lines AsPC‐1 and BxPC‐3 were used as a model system. Quantitative real‐time polymerase chain reaction (RT‐PCR), Western blot analysis, and immunofluorescence studies were used to investigate EGF‐mediated effects on NGAL expression. E‐cadherin expression was manipulated using lentiviral overexpression or small hairpin RNA constructs. NGAL promoter activity was assessed by luciferase‐reporter assay and electrophoretic mobility shift assay.

RESULTS:

NGAL expression was positively associated with tumor differentiation and was down‐regulated significantly after EGF treatment along with a concomitant reduction of E‐cadherin expression in PDAC cells. E‐cadherin down‐regulation was partly through the EGFR‐dependent mitogen‐activated protein kinase (MEK)/extracellular signal‐regulated kinase (ERK) (MEK‐ERK) signaling pathway. In addition, E‐cadherin down‐regulation reduced NGAL expression in PDAC cells, whereas overexpression of E‐cadherin led to increased NGAL expression and partly rescued the inhibition of NGAL expression by EGF. Furthermore, EGF, in part through E‐cadherin, reduced NGAL promoter activity by blocking nuclear factor κB (NF‐κB) activation.

CONCLUSIONS:

The current study demonstrated for the first time that EGF potently blocked NGAL expression in PDAC cells. This effect was mediated in part through activation of the EGFR‐MEK‐ERK signaling pathway, which, in turn, down‐regulated E‐cadherin with a subsequent reduction in NF‐κB activation. These findings illustrate a novel mechanism by which EGF regulates NGAL expression in PDAC. Cancer 2011;. © 2010 American Cancer Society.     

Levels of interleukin (IL)‐6 and IL‐8 are elevated in serum and bronchoalveolar lavage fluid of haematological patients with invasive pulmonary aspergillosis

Aspergillus spp. have been shown to induce T‐helper cell (Th) 1 and Th17 subsets resulting in elevated levels of several cytokines. The objective of this study was to analyse a bundle of cytokines in serum and bronchoalveolar lavage fluid (BALF) in patients with and without invasive pulmonary aspergillosis (IPA). This nested case‐control analysis included 10 patients with probable/proven IPA and 20 matched controls without evidence of IPA, out of a pool of prospectively enrolled (2014‐2017) adult cases with underlying haematological malignancies and suspected pulmonary infection. Serum samples were collected within 24 hours of BALF sampling. All samples were stored at ?70°C for retrospective determination of cytokines. IL‐6 and IL‐8 were significantly associated with IPA in both serum (P = .011 and P = .028) and BALF (P = .006 and P = .012, respectively), and a trend was observed for serum IL‐10 (P = .059). In multivariate conditional logistic regression analysis, IL‐10 remained a significant predictor of IPA in serum and IL‐8 among BALF cytokines. In conclusion, levels of IL‐6 and IL‐8 were significantly associated with probable/proven IPA, and a similar trend was observed for serum IL‐10. Future cohort studies should determine the diagnostic potential of these cytokines for IPA, and evaluate combinations with other IPA biomarkers/diagnostic tests.     

Simultaneous NF‐κB inhibition and E‐cadherin upregulation mediate mutually synergistic anticancer activity of celastrol and SAHA in vitro and in vivo

Suberoylanilide hydroxamic acid (SAHA) is a promising histone deacetylase (HDAC) inhibitor approved by the US Food and Drug Administration (FDA) and whose clinical application for solid tumours is partially limited by decreased susceptibility in cancer cells due to nuclear factor (NF)‐κB activation. As an NF‐κB inhibitor, celastrol exhibits potent anticancer effects but has failed to enter clinical trials due to its toxicity. In this report, we demonstrated that the combination of celastrol and SAHA exerted substantial synergistic efficacy against human cancer cells in vitro and in vivo accompanied by enhanced caspase‐mediated apoptosis. This drug combination inhibited the activation of NF‐κB caused by SAHA monotherapy and consequently led to increased apoptosis in cancer cells. Interestingly, E‐cadherin was dramatically downregulated in celastrol‐resistant cancer cells, and E‐cadherin expression was closely related to decreased sensitivity to celastrol. However, our combination treatment significantly augmented the expression of E‐cadherin, suggesting that mutual mechanisms contributed to the synergistic anticancer activity. Furthermore, the enhanced anticancer efficacy of celastrol combined with SAHA was validated in a human lung cancer 95‐D xenograft model without increased toxicity. Taken together, our data demonstrated the synergistic anticancer effects of celastrol and SAHA due to their reciprocal sensitisation, which was simultaneously regulated by NF‐κB and E‐cadherin; thus, the combination of celastrol and SAHA was superior to other combination regimens that rely on a single mechanism. Our findings not only open new opportunities for the clinical development of SAHA but should also motivate the clinical investigation of celastrol, which has been hampered by its toxicity.     

The prognostic value of E‐cadherin in gastric cancer: A meta‐analysis

The prognostic impact of E‐cadherin downregulation in gastric cancer has been assessed for years while the results are controversial and heterogeneous. We thus comprehensively reviewed the evidence for evaluation of E‐cadherin expression in gastric cancer to determine this effect. We searched PubMed and Embase to identify eligible studies, and 26 studies comprising 4,383 gastric cancer patients were included to assess the association between E‐cadherin immunohistochemical expression and overall survival (OS) and clinicopathological characteristics. Summary hazard ratios (HRs) or odds ratios (ORs) with 95% confidence interval (95% CI) were calculated to estimate the effect. We also performed meta‐regression and subgroup analysis according to study location, publication year, number of patients, quality score of studies and cut‐off value. Reduced E‐cadherin expression was significantly correlated with poor OS of gastric cancer patients (HR 1.62, 95% CI 1.34–1.96). Subgroup analysis indicated that E‐cadherin low‐expression had an unfavorable impact on OS in Asian patients (HR 1.87, 95% CI 1.45–2.41). Moreover, downregulation of E‐cadherin was significantly associated with TNM stage (OR 2.52, 95% CI 1.85–3.43), the depth of invasion (OR 2.01, 95% CI 1.39–2.90), lymph node metastasis (OR 2.39, 95% CI 1.68–3.40), distant metastasis (OR 2.23, 95% CI 1.21–4.11), grade of differentiation (OR 2.26, 95% CI 1.60–3.21), vascular invasion (OR 1.86, 95% CI 1.10–3.13) and histological type of gastric cancer (OR 4.22, 95% CI 2.96–6.02). This meta‐analysis revealed that E‐cadherin expression might be a predicative factor of poor prognosis for gastric cancer particularly in Asia.     

Long‐term prognostic significance of interleukin‐17‐producing T cells in patients with non‐small cell lung cancer

The presence of interleukin (IL)‐17‐producing T cells has recently been reported in non‐small cell lung cancer (NSCLC) patients. However, the long‐term prognostic significance of these populations in NSCLC patients remains unknown. In the present study, we collected peripheral blood from 82 NSCLC patients and 22 normal healthy donors (NC). Percentages of IL‐17‐producing CD4⁺T (Th17), CD8⁺T (Tc17) and γδT cells (γδT17) were measured to determine their association with clinical outcomes and overall survival (OS) in NSCLC. All NSCLC patients were followed up until July 2018. Median follow‐up time was 13.5 months (range 1‐87 months). The 3‐ and 5‐year survival rate was 27% and 19.6%, respectively. We found that Th17 cells and γδT17 cells were significantly increased, whereas Tc17 cells were markedly decreased in patients with NSCLC compared with those in NC. In addition, Th17 cells were significantly positively associated with T helper type 1 cells (Th1), whereas γδT17 cells were significantly negatively associated with γδT ⁺ interferon (IFN)‐γ⁺ cells. High percentages of peripheral Tc17 cells were significantly associated with favorable 5‐year OS (P = .025), especially in patients with early TNM stage (P = .016). Furthermore, high percentages of peripheral Th17 cells were positively associated with favorable 5‐year OS in patients with late TNM stage (P = .002). However, no significant association was observed between γδT17 cells and OS, regardless of the TNM stage. In conclusion, our findings suggest that enhanced Th17 and reduced Tc17 cells in the peripheral blood could be a significant predictor of a favorable prognosis for NSCLC patients.     

Potential roles of microRNA‐29a in the molecular pathophysiology of T‐cell acute lymphoblastic leukemia

Recent evidence has shown that deregulated expression of members of the microRNA‐29 (miR‐29) family may play a critical role in human cancer, including hematological malignancies. However, the roles of miR‐29 in the molecular pathophysiology of T‐cell acute lymphoblastic leukemia (T‐ALL) has not been investigated. Here, we show that lower levels of miR‐29a were significantly associated with higher blast counts in the bone marrow and with increased disease‐free survival in T‐ALL patients. Furthermore, miR‐29a levels are extremely reduced in T‐ALL cells compared to normal T cells. Microarray analysis following introduction of synthetic miR‐29a mimics into Jurkat cells revealed the downregulation of several predicted targets (CDK6, PXDN, MCL1, PIK3R1, and CXXC6), including targets with roles in active and passive DNA demethylation (such as DNMT3a, DNMT3b, and members of the TET family and TDG). Restoring miR‐29a levels in Jurkat and Molt‐4 T‐ALL cells led to the demethylation of many genes commonly methylated in T‐ALL. Overall, our results suggest that reduced miR‐29a levels may contribute to the altered epigenetic status of T‐ALL, highlighting its relevance in the physiopathology of this disease.     

DN‐R175H p53 mutation is more effective than p53 interference in inducing epithelial disorganization and activation of proliferation signals in human carcinoma cells: Role of E‐cadherin

One of the hallmarks of carcinomas is epithelial disorganization, linked to overexpression of matrix metalloproteases (MMP) like MMP‐9, loss of intercellular E‐cadherin and activation of epidermal growth receptor (EGFR/erbB1). Since the p53 tumor suppressor pathway is inactivated in most human cancers due to gene mutations or defective wt p53 signaling, we now investigated in human wt p53 breast carcinoma MCF‐7 cells, whether single treatment with the p53 transactivation pharmacological inhibitor pifithrin‐α, transient p53 siRNA interference or stable insertion of a dominant‐negative (DN) R175H p53 mutant increase: (i) EGFR/erbB1 activation, (ii) MMP‐9 expression and (iii) loss of surface E‐cadherin. Transient abrogation of wt p53 function increased phosphorylation of EGFR/erbB1 and MMP‐9 expression. However, all these effects were much more pronounced in cells stably transduced with the dominant negative–Arg‐175His mutant p53 (DN‐R175H mutant p53), which also showed loss of epithelial cytoarchitecture and extensive E‐cadherin downregulation. Collectively, these results support the notion that the DN‐R175H mutant p53 exerts a gain of oncogenic function by promoting disruption of E‐cadherin intercellular contacts and activation of proliferation signals. Our data suggests that epithelial shape and growth control are unequally affected depending on how wt p53 function is impaired and whether partial or full tumor suppressor activity is lost. © 2009 UICC     

Dual tumor‐suppressors miR‐139‐5p and miR‐139‐3p targeting matrix metalloprotease 11 in bladder cancer

Our recent study of the microRNA (miRNA) expression signature of bladder cancer (BC) by deep‐sequencing revealed that two miRNA, microRNA‐139‐5p/microRNA‐139‐3p were significantly downregulated in BC tissues. The aim of this study was to investigate the functional roles of these miRNA and their modulation of cancer networks in BC cells. Functional assays of BC cells were performed using transfection of mature miRNA or small interfering RNA (siRNA). Genome‐wide gene expression analysis, in silico analysis and dual‐luciferase reporter assays were applied to identify miRNA targets. The associations between the expression of miRNA and its targets and overall survival were estimated by the Kaplan–Meier method. Gain‐of‐function studies showed that miR‐139‐5p and miR‐139‐3p significantly inhibited cell migration and invasion by BC cells. The matrix metalloprotease 11 gene (MMP11) was identified as a direct target of miR‐139‐5p and miR‐139‐3p. Kaplan–Meier survival curves showed that higher expression of MMP11 predicted shorter survival of BC patients (P = 0.029). Downregulated miR‐139‐5p or miR‐139‐3p enhanced BC cell migration and invasion in BC cells. MMP11 was directly regulated by these miRNA and might be a good prognostic marker for survival of BC patients.