Soluble-E-cadherin activates HER and IAP family members in HER2+ and TNBC human breast cancers

Regulation of Soluble E-Cadherin Signaling in Non-Small-Cell Lung Cancer Cells by Nicotine, BDNF, and β-Adrenergic Receptor Ligands

The ectodomain of the transmembrane protein E-cadherin can be cleaved and released in a soluble form referred to as soluble E-cadherin, or sE-cad, accounting for decreased E-cadherin levels at the cell surface. Among the proteases implicated in this cleavage are matrix metalloproteases (MMP), including MMP9. Opposite functions have been reported for full-length E-cadherin and sE-cad. In this study, we found increased MMP9 levels in the media of two non-small cell lung cancer (NSCLC) cell lines, A549 and H1299, treated with BDNF, nicotine, or epinephrine that were decreased upon cell treatment with the β-adrenergic receptor blocker propranolol. Increased MMP9 levels correlated with increased sE-cad levels in A549 cell media, and knockdown of MMP9 in A549 cells led to downregulation of sE-cad levels in the media. Previously, we reported that A549 and H1299 cell viability increased with nicotine and/or BDNF treatment and decreased upon treatment with propranolol. In investigating the function of sE-cad, we found that immunodepletion of sE-cad from the media of A549 cells untreated or treated with BDNF, nicotine, or epinephrine reduced activation of EGFR and IGF-1R, decreased PI3K and ERK1/2 activities, increased p53 activation, decreased cell viability, and increased apoptosis, while no effects were found using H1299 cells under all conditions tested.

Soluble E-cadherin promotes invasiveness of neoplastic cells in salivary gland carcinoma ex pleomorphic adenoma

BACKGROUND

Soluble E-cadherin (sEcad), a tumor suppressor gene, has pro-oncogenic effects by binding to human epithelial growth factor receptor 2 (HER-2). In our previous study, 1/3 of carcinoma ex pleomorphic adenoma (CXPA) cases had HER-2 amplification, which is associated with tumorigenesis and malignancy. This study examines the role of sEcad in HER-2 amplified CXPA.

METHODS

Immunohistochemistry was used to examine E-cadherin (Ecad) expression in HER-2-amplified CXPA samples (n = 35). Western blot and ELISA were used to detect sEcad in two samples with Ecad and HER-2 overexpression and CXPA cell line. Lentivirus-mediated transfection was performed to knock down sEcad in CXPA cells. The cell proliferation, wound healing, and transwell assays were used to compare sEcad-knockdown cells with cells pretreated with recombinant human sEcad (rhEcad/Fc). sEcad and HER-2 interaction was determined through co-immunoprecipitation. RNA-sequencing, differential expression analysis, GO and KEGG analysis were used to identify sEcad-related signaling pathways and their protein phosphorylation levels were verified by western blotting.

RESULTS

Ecad was overexpressed in 77.1% of HER-2-positive CXPA, and sEcad was found in the CXPA cell line and two samples. sEcad promoted CXPA migration and invasion in vitro without sEcad and HER-2 interaction. sEcad-related differentially expressed genes were enriched in the IL-17, cAMP, and MAPK signaling pathways. Furthermore, sEcad activated the phosphorylation of Akt and MAPK/ERK signaling pathways.

CONCLUSIONS

Most HER-2⁺ CXPAs express Ecad. sEcad could affect the invasiveness and migration of in vitro CXPA cells without HER-2. sEcad may be a therapeutic biomarker for CXPA patients.

HER2-CDH1 Interaction via Wnt/B-Catenin Is Associated with Patients' Survival in HER2-Positive Metastatic Gastric Adenocarcinoma

Simple Summary

A deeper understanding of the molecular mechanisms involved in gastric cacner (GC) pathologenesis would help the identification of prognostic biomarkers and the development of new treatments. Human epidermal growth factor receptor 2 (HER2/ErbB2), a membrane-bound receptor of the EGFR family, may be overexpressed in GC. Trastuzumab is a HER2 inhibitor used to treat HER2+ metastatic gastric cancer (mGC). The present study aims to investigate the relationship between CDH1 mRNA expression and HER2-positivity in mGC using a multiplexed gene expression profile in two series of GC patients: 38 HER2+ and HER2- mGC and 36 HER2- GC with and without metastasis. Our results revealed the relationship between CDH1 and HER2 mRNA expression in mGC via the canonical WNT/β-catenin pathway and identified EGF as an independent prognostic biomarker for survival.

Abstract

Trastuzumab is a human epidermal growth factor receptor 2 (HER2) inhibitor used to treat HER2+ metastatic gastric cancer (mGC). The present study aims to investigate the relationship between CDH1 mRNA expression and HER2-positivity in mGC using a multiplexed gene expression profile in two series of gastric cancer (GC): Series 1 (n = 38): HER2+ and HER2- mGC; Series 2 (n = 36) HER2- GC with and without metastasis. To confirm the results, the same expression profiles were analyzed in 354 GC from The Cancer Genome Atlas (TCGA) dataset. The difference in gene expression connected HER2 overexpression with canonical wingless-type (Wnt)/β-catenin pathway and immunohistochemical (IHC) expression loss of E-cadherin (E-CAD). CDH1 mRNA expression was simultaneously associated with the rs16260-A variant and an increase in E-CAD expression. Differences in retinoic acid receptor alfa (RARA), RPL19 (coding for the 60S ribosomal L19 protein), catenin delta 1 (CTNND1), and epidermal growth factor (EGF) mRNA levels—all included in the Wnt/β-catenin pathway—were found associated with overall survival (OS). RARA, CTNND1, and EGF resulted in independent OS prognostic factors. EGF was confirmed as an independent factor along with TNM stage in HER2-overpressed mGC from TCGA collection. Our study highlighted factors involved in the WNT/β-catenin pathway that interconnected E-CAD with HER2 overexpression and patient survival.

The Cross-Talk Between EGFR and E-Cadherin

Epidermal growth factor receptor (EGFR) and adhesion protein E-cadherin are major regulators of proliferation and differentiation in epithelial cells. Consistently, defects in both EGFR and E-cadherin-mediated intercellular adhesion are linked to various malignancies. These defects in either are further exacerbated by the reciprocal interactions between the two transmembrane proteins. On the one hand, EGFR can destabilize E-cadherin adhesion by increasing E-cadherin endocytosis, modifying its interactions with cytoskeleton and decreasing its expression, thus promoting tumorigenesis. On the other hand, E-cadherin regulates EGFR localization and tunes its activity. As a result, loss and mutations of E-cadherin promote cancer cell invasion due to uncontrolled activation of EGFR, which displays enhanced surface motility and changes in endocytosis. In this minireview, we discuss the molecular and cellular mechanisms of the cross-talk between E-cadherin and EGFR, highlighting emerging evidence for the role of endocytosis in this feedback, as well as its relevance to tissue morphogenesis, homeostasis and cancer progression.

Subunits of BK channels promote breast cancer development and modulate responses to endocrine treatment in preclinical models

BACKGROUND AND PURPOSE

Pore-forming α subunits of the voltage- and Ca²⁺ -activated K⁺ channel with large conductance (BKα) promote malignant phenotypes of breast tumour cells. Auxiliary subunits such as the leucine-rich repeat containing 26 (LRRC26) protein, also termed BKγ1, may be required to permit activation of BK currents at a depolarized resting membrane potential that frequently occur in non-excitable tumour cells.

EXPERIMENTAL APPROACH

Anti-tumour effects of BKα loss were investigated in breast tumour-bearing MMTV-PyMT transgenic BKα knockout (KO) mice, primary MMTV-PyMT cell cultures, and in a syngeneic transplantation model of breast cancer derived from these cells. The therapeutic relevance of BK channels in the context of endocrine treatment was assessed in human breast cancer cell lines expressing either low (MCF-7) or high (MDA-MB-453) levels of BKα and BKγ1, as well as in BKα-negative MDA-MB-157.

KEY RESULTS

BKα promoted breast cancer onset and overall survival in preclinical models. Conversely, lack of BKα and/or knockdown of BKγ1 attenuated proliferation of murine and human breast cancer cells in vitro. At low concentrations, tamoxifen and its major active metabolites stimulated proliferation of BKα/γ1-positive breast cancer cells, independent of the genomic signalling controlled by the oestrogen receptor. Finally, tamoxifen increased the relative survival time of BKα KO but not of wild-type tumour cell recipient mice.

CONCLUSION AND IMPLICATIONS

Breast cancer initiation, progression, and tamoxifen sensitivity depend on functional BK channels thereby providing a rationale for the future exploration of the oncogenic actions of BK channels in clinical outcomes with anti-oestrogen therapy.

E-cadherin-Fc chimera protein matrix enhances cancer stem-like properties and induces mesenchymal features in colon cancer cells

Cancer stem cells (CSC) are a subpopulation of tumor cells with properties of high tumorigenicity and drug resistance, which lead to recurrence and poor prognosis. Although a better understanding of CSC is essential for developing cancer therapies, scarcity of the CSC population has hindered such analyses. The aim of the present study was to elucidate whether the E-cadherin-Fc chimera protein (E-cad-Fc) enhances cancer stem-like properties because studies show that soluble E-cadherin stimulates human epithelial growth factor receptor (EGFR) and downstream signaling pathways that are reported to play a crucial role in CSC. For this purpose, we used ornithine decarboxylase (ODC)-degron-transduced (Degron(+)) KM12SM cells as a CSC model that retains relatively low CSC properties. Compared to cultures without E-cad-Fc treatment, we found that E-cad-Fc treatment further suppressed proteasome activity and largely enhanced cancer stem-like properties of ODC-degron-transduced KM12SM cells. These results include increased expression of stem cell markers Lgr5, Bmi-1, SOX9, CD44, and CD44v9, aldehyde dehydrogenase (ALDH), and enhancement of robust spheroid formation, and chemoresistance to 5-fluorouracil (5-FU) and oxaliplatin (L-OHP). These effects could be attributed to activation of the EGFR pathway as identified by extensive phosphorylation of EGFR, ERK, PI3K, AKT, and mTOR. In SW480 cells, E-cad-Fc matrix induced some CSC markers such as CD44v9 and ALDH. We also found that E-cad-Fc matrix showed high efficiency of inducing mesenchymal changes in colon cancer cells. Our data suggest that the E-cad-Fc matrix may enhance CSC properties such as enhancement of chemoresistance and sphere formation.

Targeting the Temporal Dynamics of Hypoxia-Induced Tumor-Secreted Factors Halts Tumor Migration

Targeting microenvironmental factors that foster migratory cell phenotypes is a promising strategy for halting tumor migration. However, lack of mechanistic understanding of the emergence of migratory phenotypes impedes pharmaceutical drug development. Using our three-dimensional microtumor model with tight control over tumor size, we recapitulated the tumor size-induced hypoxic microenvironment and emergence of migratory phenotypes in microtumors from epithelial breast cells and patient-derived primary metastatic breast cancer cells, mesothelioma cells, and lung cancer xenograft cells. The microtumor models from various patient-derived tumor cells and patient-derived xenograft cells revealed upregulation of tumor-secreted factors, including matrix metalloproteinase-9 (MMP9), fibronectin (FN), and soluble E-cadherin, consistent with clinically reported elevated levels of FN and MMP9 in patient breast tumors compared with healthy mammary glands. Secreted factors in the conditioned media of large microtumors induced a migratory phenotype in nonhypoxic, nonmigratory small microtumors. Subsequent mathematical analyses identified a two-stage microtumor progression and migration mechanism whereby hypoxia induces a migratory phenotype in the initialization stage, which then becomes self-sustained through a positive feedback loop established among the tumor-secreted factors. Computational and experimental studies showed that inhibition of tumor-secreted factors effectively halts microtumor migration despite tumor-to-tumor variation in migration kinetics, while inhibition of hypoxia is effective only within a time window and is compromised by tumor-to-tumor variation, supporting our notion that hypoxia initiates migratory phenotypes but does not sustain it. In summary, we show that targeting temporal dynamics of evolving microenvironments, especially tumor-secreted factors during tumor progression, can halt tumor migration. SIGNIFICANCE: This study uses state-of-the-art three-dimensional microtumor models and computational approaches to highlight the temporal dynamics of tumor-secreted microenvironmental factors in inducing tumor migration.

Cut loose and run: The complex role of ADAM proteases during neural crest cell development

ADAM metalloproteases have been shown to play critical roles during development. In this review, we will describe functional evidence that implicates ADAM proteins during the genesis, migration and differentiation of neural crest cells. We will restrict our analysis to the transmembrane ADAMs as other reviews have addressed the role of extracellular metalloproteases (Christian et al. [2013] Critical Reviews in Biochemistry and Molecular Biology 48:544-560). This review will describe advances that have been obtained mainly through the use of two vertebrate model systems, the frog, and avian embryos. The role of the principal substrates of ADAMs, the cadherins, has been extensively described in other reviews, most recently in (Cousin [1997] Mechanisms of Development 148:79-88; Taneyhill and Schiffmacher [2017] Genesis, 55). The function of ADAMs in the migration of other cell types, including the immune system, wound healing and cancer has been described previously in (Dreymueller et al. [2017] Mediators of Inflammation 2017: 9621724). Our goal is to illustrate both the importance of ADAMs in controlling neural crest behavior and how neural crest cells have helped us understand the molecular interactions, substrates, and functions of ADAM proteins in vivo.

sEcad and EGF Levels Increased in Urine of Non-ferrous Metal Workers and Medium of Uroepithelial Cell Line Treated by Arsenic

Inorganic arsenic (iAs) is a carcinogen and could increase the risks of bladder, lung, and skin cancer. Mining and smelting of non-ferrous metals are common occupational arsenic exposures. In this study, 125 individuals working in non-ferrous metal smelting plants were separated into two groups according to urinary total arsenic (TAs) levels: group 1, TAs < 100 μg/g Cr; group 2, TAs ≥ 100 μg/g Cr. Demographic characteristics of participants were obtained by questionnaire interview. Levels of E-cadherin soluble ectodomain fragment (sEcad) and epidermal growth factor (EGF) in workers urine were determined by ELISA test. We found that concentrations of sEcad and EGF present in urine were significantly elevated in the high urinary arsenic group 2 compared with the low urinary arsenic group 1. Urinary levels of the shedding of E-cadherin soluble ectodomain fragment (sEcad) and epidermal growth factor (EGF) were positively related to the concentrations of iAs in urine after adjusting for the confounding effects. A positive correlation between sEcad and EGF concentrations in urine was also observed. In order to verify the effects of iAs on sEcad and EGF, the human uroepithelial cell line (SV-HUC-1) was treated with NaAsO₂ for 24 h in vitro. sEcad and EGF levels in the 4 μM NaAsO₂-treated SV-HUC-1 cell medium significantly increased compared to the control group. In conclusion, urinary levels of sEcad and EGF increased in higher urinary arsenic workers of non-ferrous metal plants and are closely associated with urinary iAs concentration. The results suggested that sEcad and EGF may potentially be preclinical prognostic factors of bladder injury and early detection in arsenic exposure individuals.

Cadherins function during the collective cell migration of Xenopus Cranial Neural Crest cells: revisiting the role of E-cadherin

Collective cell migration is a process whereby cells move while keeping contact with other cells. The Xenopus Cranial Neural Crest (CNC) is a population of cells that emerge during early embryogenesis and undergo extensive migration from the dorsal to ventral part of the embryo's head. These cells migrate collectively and require cadherin mediated cell-cell contact. In this review, we will describe the key features of Xenopus CNC migration including the key molecules driving their migration. We will also review the role of the various cadherins during Xenopus CNC emergence and migration. Lastly, we will discuss the recent and seemingly controversial findings showing that E-cadherin presence is essential for CNC migration.

The ectodomain of cadherin-11 binds to erbB2 and stimulates Akt phosphorylation to promote cranial neural crest cell migration

During development, a multi-potent group of cells known as the cranial neural crest (CNC) migrate to form craniofacial structures. Proper migration of these cells requires proteolysis of cell adhesion molecules, such as cadherins. In Xenopus laevis, preventing extracellular cleavage of cadherin-11 impairs CNC migration. However, overexpression of the soluble cleavage product (EC1-3) is capable of rescuing this phenotype. The mechanism by which EC1-3 promotes CNC migration has not been investigated until now. Here we show that EC1-3 stimulates phosphorylation of Akt, a target of PI3K, in X.laevis CNC. Through immunoprecipitation experiments, we determined that EC1-3 interacts with all ErbB receptors, PDGFRα, and FGFR1. Of these receptors, only ErbB2 was able to produce an increase in Akt phosphorylation upon treatment with a recombinant EC1-3. This increase was abrogated by mubritinib, an inhibitor of ErbB2. We were able to recapitulate this decrease in Akt phosphorylation in vivo by knocking down ErbB2 in CNC cells. Knockdown of the receptor also significantly reduced CNC migration in vivo. We confirmed the importance of ErbB2 and ErbB receptor signaling in CNC migration using mubritinib and canertinib, respectively. Mubritinib and the PI3K inhibitor LY294002 significantly decreased cell migration while canertinib nearly prevented it altogether. These data show that ErbB2 and Akt are important for CNC migration and implicate other ErbB receptors and Akt-independent signaling pathways. Our findings provide the first example of a functional interaction between the extracellular domain of a type II classical cadherin and growth factor receptors.

Dual control of pcdh8l/PCNS expression and function in Xenopus laevis neural crest cells by adam13/33 via the transcription factors tfap2α and arid3a

Adam13/33 is a cell surface metalloprotease critical for cranial neural crest (CNC) cell migration. It can cleave multiple substrates including itself, fibronectin, ephrinB, cadherin-11, pcdh8 and pcdh8l (this work). Cleavage of cadherin-11 produces an extracellular fragment that promotes CNC migration. In addition, the adam13 cytoplasmic domain is cleaved by gamma secretase, translocates into the nucleus and regulates multiple genes. Here, we show that adam13 interacts with the arid3a/dril1/Bright transcription factor. This interaction promotes a proteolytic cleavage of arid3a and its translocation to the nucleus where it regulates another transcription factor: tfap2α. Tfap2α in turn activates multiple genes including the protocadherin pcdh8l (PCNS). The proteolytic activity of adam13 is critical for the release of arid3a from the plasma membrane while the cytoplasmic domain appears critical for the cleavage of arid3a. In addition to this transcriptional control of pcdh8l, adam13 cleaves pcdh8l generating an extracellular fragment that also regulates cell migration.

Expression of human endogenous retrovirus-K is strongly associated with the basal-like breast cancer phenotype

Human endogenous retroviruses (HERVs), which make up approximately 8% of the human genome, are overexpressed in some breast cancer cells and tissues but without regard to cancer subtype. We, therefore, analyzed TCGA RNA-Seq data to evaluate differences in expression of the HERV-K family in breast cancers of the various subtypes. Four HERV-K loci on different chromosomes were analyzed in basal, Her2E, LumA, and LumB breast cancer subtypes of 512 breast cancer patients with invasive ductal carcinoma (IDC). The results for all four loci showed higher HERV-K expression in the basal subtype, suggesting similar mechanisms of regulation regardless of locus. Expression of the HERV-K envelope gene (env) was highly significantly increased in basal tumors in comparison with the also-upregulated expression of other HERV-K genes. Analysis of reverse-phase protein array data indicated that increased expression of HERV-K is associated with decreased mutation of H-Ras (wild-type). Our results show elevation of HERV-K expression exclusively in the basal subtype of IDC breast cancer (as opposed to the other subtypes) and suggest HERV-K as a possible target for cancer vaccines or immunotherapy against this highly aggressive form of breast cancer.

Roles of RUNX in Hippo Pathway Signaling

The Runt-domain (RD) transcription factors (RUNX genes) are an important family of transcriptional mediators that interact with a variety of proteins including the Hippo pathway effector proteins, YAP and TAZ. In this chapter we focus on two examples of RUNX-TAZ/YAP interactions that have particular significance in human cancer. Specifically, recent evidence has found that RUNX2 cooperates with TAZ to promote epithelial to mesenchymal transition mediated by the soluble N-terminal ectodomain of E-Cadherin, sE-Cad. Contrastingly, in gastric cancer, RUNX3 acts as a tumor suppressor via inhibition of the YAP-TEAD complex and disruption of downstream YAP-mediated gene transcription and the oncogenic phenotype. The reports highlighted in this chapter add to the growing repertoire of instances of Hippo pathway crosstalk that have been identified in cancer. Elucidation of these increasingly complex interactions may help to identify novel strategies to target Hippo pathway dysregulation in human cancer.

Prognostic value of HER2 status in bladder transitional cell carcinoma revealed by both IHC and BDISH techniques

BACKGROUND

Her2/neu is an oncogene that plays an important role in the pathogenesis of many cancer types. In bladder carcinoma (BC), the clinical significance of Her2/neu status remains under-investigated and poorly linked to the patients' clinic-pathological features and survival status. Thus, the current study was conducted to assess Her2/neu status in a cohort of patients' in Saudi Arabia, and to explore its prognostic value in BC.

METHODS

A total of 160 consent patients of transitional cell carcinoma (TCC) of bladder were arranged on a tissue microarray (TMA) and stained by immunohistochemistry (IHC) and bright-field dual in situ hybridization (BDISH) methods. The intensity of Her2/neu protein receptor immunostaining was evaluated, correlated to Her2/neu gene amplification status in TCC and assessed for potential clinical value by correlation measures.

RESULTS

IHC data demonstrated that Her2/neu protein is expressed in 60 % (2+ and 3+) of our TCC patient's cohort from Saudi Arabia. Her2/neu gene amplification is detected in 25 % by BDISH. There was a strong association between Her2/neu protein levels and lymph node invasion (p = 0.04), tumor stage (p = 0.002), vascular invasion and borderline significance with distant metastasis (p = 0.07). Amplification of Her2/neu gene was associated with tumor grade (p = 0.03) and poor disease-specific survival (p = 0.02), in that, patients with non-amplified Her2/neu gene live longer. Interestingly, there was a reasonable concordance rate (71 %) between IHC and BDISH data in the analyzed cohort.

CONCLUSION

The study showed that 25 % of our patients' cohort has Her2/neu over-expression. This Her2/neu (over-expression/amplification) status was concordant using either IHC or BDISH and significantly associated with disease aggressiveness and poor outcome. These findings suggested a potential impact of anti-Her2 targeted therapy in the treatment of bladder cancer with amplified/overexpressed HER2 that needs further investigation.

RUNX2 and TAZ-dependent signaling pathways regulate soluble E-Cadherin levels and tumorsphere formation in breast cancer cells

Intratumoral heterogeneity and treatment resistance drive breast cancer (BC) metastasis and recurrence. The RUNX2 transcription factor is upregulated in early stage luminal BC. However, the precise mechanism by which RUNX2 regulates an oncogenic phenotype in luminal BCs remains an enigma. We show that RUNX2 is predictive of poor overall survival in BC patients. RUNX2 associated with the TAZ transcriptional co-activator to promote a tumorigenic phenotype that was inhibited by knockdown of TAZ. RUNX2 increased endogenous TAZ translocation to the nucleus, which was prevented by inhibiting RUNX2. RUNX2/TAZ interaction was associated with ectodomain shedding of an oncogenic soluble E-Cadherin fragment (sE-Cad), which is known to cooperate with human epidermal growth factor receptor-2 (HER2/ErbB2) to increase BC growth. Neutralizing E-Cadherin antibodies or TAZ knockdown reduced the levels of sE-Cad in RUNX2-expressing BC cells and inhibited tumorsphere formation. RUNX2 expression also increased HER2-mediated tumorsphere size, which was reduced after treatment with the HER2-targeting agents Herceptin and lapatinib. These data support a novel role for RUNX2 in promoting an oncogenic phenotype in luminal BC in the context of TAZ, sE-Cad, and HER2. Using this signaling pathway to monitor BC cell oncogenic activity will accelerate the discovery of new therapeutic modalities to treat BC patients.

Effects of vascular endothelial growth factor on osteoblasts and osteoclasts

INTRODUCTION

Bone remodeling is crucial to the success of many dental procedures and is tightly regulated. Vascular endothelial growth factor (VEGF), a key cytokine for angiogenesis, is also an important regulator of bone remodeling. We aimed to examine the mechanisms by which VEGF induces bone remodeling by studying its effects on cultured osteoblasts and osteoclasts.

METHODS

Preosteoblastic MC3T3-E1 cells were treated with vehicle or VEGF-A165. Cell proliferation, migration, and invasion potentials were assessed. Preosteoclastic RAW264.7 cells were treated with vehicle or VEGF with or without the receptor activator of nuclear factor kappa-B ligand (RANKL), and osteoclast formation was measured with tartrate-resistant acid phosphatase staining. Conditioned media from vehicle-treated or VEGF-treated MC3T3-E1 cells were tested for the levels of RANKL and osteoprotegerin (OPG) and were used to treat RAW264.7 cells to observe osteoclast formation.

RESULTS

VEGF significantly induced MC3T3-E1 cell proliferation, migration, and invasion. VEGF did not directly induce osteoclastogenesis but significantly increased the RANKL/OPG ratio in the conditioned media from the MC3T3-E1 cultures; this significantly increased osteoclast formation.

CONCLUSIONS

VEGF stimulates osteoclast differentiation by increasing the osteoblastic RANKL/OPG ratio but has no direct effect on osteoclast precursor cells, and it induces osteoblast proliferation, migration, and invasion potentials in vitro.

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.

Protein arginine methyltransferase 7 promotes breast cancer cell invasion through the induction of MMP9 expression

Recent evidence points to the protein arginine methyltransferase (PRMT) family of enzymes playing critical roles in cancer. PRMT7 has been identified in several gene expression studies to be associated with increased metastasis and decreased survival in breast cancer patients. However, this has not been extensively studied. Here we report that PRMT7 expression is significantly upregulated in both primary breast tumour tissues and in breast cancer lymph node metastases. We have demonstrated that reducing PRMT7 levels in invasive breast cancer cells using RNA interference significantly decreased cell invasion in vitro and metastasis in vivo. Conversely, overexpression of PRMT7 in non-aggressive MCF7 cells enhanced their invasiveness. Furthermore, we show that PRMT7 induces the expression of matrix metalloproteinase 9 (MMP9), a well-known mediator of breast cancer metastasis. Importantly, we significantly rescued invasion of aggressive breast cancer cells depleted of PRMT7 by the exogenous expression of MMP9. Our results demonstrate that upregulation of PRMT7 in breast cancer may have a significant role in promoting cell invasion through the regulation of MMP9. This identifies PRMT7 as a novel and potentially significant biomarker and therapeutic target for breast cancer.

Carcinoma cells induce lumen filling and EMT in epithelial cells through soluble E-cadherin-mediated activation of EGFR

In epithelial cancers, carcinoma cells coexist with normal cells. Although it is known that the tumor microenvironment (TME) plays a pivotal role in cancer progression, it is not completely understood how the tumor influences adjacent normal epithelial cells. In this study, a three-dimensional co-culture system comprising non-transformed epithelial cells (MDCK) and transformed carcinoma cells (MSV-MDCK) was used to demonstrate that carcinoma cells sequentially induce preneoplastic lumen filling and epithelial-mesenchymal transition (EMT) in epithelial cysts. MMP-9 secreted by carcinoma cells cleaves cellular E-cadherin (encoded by CDH1) from epithelial cells to generate soluble E-cadherin (sE-cad), a pro-oncogenic protein. We show that sE-cad induces EGFR activation, resulting in lumen filling in MDCK cysts. Long-term sE-cad treatment induced EMT. sE-cad caused lumen filling by induction of the ERK signaling pathway and triggered EMT through the sustained activation of the AKT pathway. Although it is known that sE-cad induces MMP-9 release and consequent EGFR activation in tumor cells, our results, for the first time, demonstrate that carcinoma cells can induce sE-cad shedding in adjacent epithelial cells, which leads to EGFR activation and the eventual transdifferentiation of the normal epithelial cells.

Inflammation-induced desmoglein-2 ectodomain shedding compromises the mucosal barrier

Proinflammatory cytokines promote desmoglein-2 (Dsg2) ectodomain shedding in intestinal epithelial cells. Epithelial exposure to Dsg2 ectodomains compromises intercellular adhesion while also promoting proliferation. These findings identify mechanisms by which mucosal inflammation–induced cleavage of Dsg2 influences intestinal epithelial homeostasis.

Desmosomal cadherins mediate intercellular adhesion and control epithelial homeostasis. Recent studies show that proteinases play an important role in the pathobiology of cancer by targeting epithelial intercellular junction proteins such as cadherins. Here we describe the proinflammatory cytokine-induced activation of matrix metalloproteinase 9 and a disintegrin and metalloproteinase domain–containing protein 10, which promote the shedding of desmosomal cadherin desmoglein-2 (Dsg2) ectodomains in intestinal epithelial cells. Epithelial exposure to Dsg2 ectodomains compromises intercellular adhesion by promoting the relocalization of endogenous Dsg2 and E-cadherin from the plasma membrane while also promoting proliferation by activation of human epidermal growth factor receptor 2/3 signaling. Cadherin ectodomains were detected in the inflamed intestinal mucosa of mice with colitis and patients with ulcerative colitis. Taken together, our findings reveal a novel response pathway in which inflammation-induced modification of columnar epithelial cell cadherins decreases intercellular adhesion while enhancing cellular proliferation, which may serve as a compensatory mechanism to promote repair.

Abnormal expression of serum soluble E-cadherin is correlated with clinicopathological features and prognosis of breast cancer

BACKGROUND

Increased amounts of soluble E-cadherin (E-cad) have been found in the serum in various cancers, but the role of serum soluble E-cad in the prognosis of breast cancer patients has not been explored in Asian populations.

MATERIAL/METHOD

Blood samples from 111 consecutive patients diagnosed with breast cancer and 55 healthy controls were investigated.Serum soluble E-cad expression levels were measured by enzyme-linked immunosorbent assay(ELISA) with an immunoassay kit according to the manufacturer's directions. Kaplan-Meier analyses were used to evaluate the association between serum soluble E-cad expression level and survival. All statistical tests were 2-sided.

RESULTS

The serum levels of soluble E-cad in breast cancer patients were significantly higher than those of the control group (2218.9±319.6 ng/ml vs. 742.8±91.7 ng/ml, p<0.001). Serum levels of soluble E-cad correlated significantly with TNM stage (P=0.007), tumor grade (P=0.03), and lymph node metastasis (P<0.001). Kaplan-Meier analysis with the log-rank test indicated that high serum levels of soluble E-cad had a significant impact on overall survival (55.4% vs. 81.4%; P=0.032) and disease-free survival (36.8% vs. 67.8%; P=0.002) in breast cancer. Multivariate analysis revealed that serum levels of soluble E-cad were independently associated with overall survival and disease-free survival in breast cancer patients.

CONCLUSIONS

Serum soluble E-cad level is an independent prognostic factor in Asian breast cancer patients.

Levels of soluble E-cadherin in breast, gastric, and colorectal cancers

Soluble E-cadherin is a 80 kDa protein fragment coming from the proteolytic cleavage of the extracellular domain of the full length epithelial cadherin, a molecule involved in cell adhesion/polarity and tissue morphogenesis. In comparison with normal epithelia, cancer cells show a decreased cadherin-mediated intercellular adhesion, and sE-cad levels normally increase in body fluids (blood and urine). This review focuses on soluble E-cadherin in sera of patients affected by three solid cancers (breast, gastric, and colorectal cancers) and how its levels correlate or not with some cancer parameters (e.g., dimension, progression, and localisation). We will describe the main proteomics approaches adopted to measure sE-cad both in vivo and in vitro and the most important findings about its behaviour in cancer dynamics.