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Xiao D, Xiong M, Wang X, Lyu M, Sun H, Cui Y, Chen C, Jiang Z, Sun F. Regulation of the Function and Expression of EpCAM. Biomedicines 2024; 12:1129. [PMID: 38791091 PMCID: PMC11117676 DOI: 10.3390/biomedicines12051129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Revised: 05/11/2024] [Accepted: 05/14/2024] [Indexed: 05/26/2024] Open
Abstract
The epithelial cell adhesion molecule (EpCAM) is a single transmembrane protein on the cell surface. Given its strong expression on epithelial cells and epithelial cell-derived tumors, EpCAM has been identified as a biomarker for circulating tumor cells (CTCs) and exosomes and a target for cancer therapy. As a cell adhesion molecule, EpCAM has a crystal structure that indicates that it forms a cis-dimer first and then probably a trans-tetramer to mediate intercellular adhesion. Through regulated intramembrane proteolysis (RIP), EpCAM and its proteolytic fragments are also able to regulate multiple signaling pathways, Wnt signaling in particular. Although great progress has been made, increasingly more findings have revealed the context-specific expression and function patterns of EpCAM and their regulation processes, which necessitates further studies to determine the structure, function, and expression of EpCAM under both physiological and pathological conditions, broadening its application in basic and translational cancer research.
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Affiliation(s)
- Di Xiao
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan 430081, China; (D.X.); (M.X.); (X.W.); (M.L.); (H.S.); (Y.C.)
- Institute of Biology and Medicine, Wuhan University of Science and Technology, Wuhan 430081, China
| | - Mingrui Xiong
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan 430081, China; (D.X.); (M.X.); (X.W.); (M.L.); (H.S.); (Y.C.)
- Institute of Biology and Medicine, Wuhan University of Science and Technology, Wuhan 430081, China
| | - Xin Wang
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan 430081, China; (D.X.); (M.X.); (X.W.); (M.L.); (H.S.); (Y.C.)
- Institute of Biology and Medicine, Wuhan University of Science and Technology, Wuhan 430081, China
| | - Mengqing Lyu
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan 430081, China; (D.X.); (M.X.); (X.W.); (M.L.); (H.S.); (Y.C.)
- Institute of Biology and Medicine, Wuhan University of Science and Technology, Wuhan 430081, China
| | - Hanxiang Sun
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan 430081, China; (D.X.); (M.X.); (X.W.); (M.L.); (H.S.); (Y.C.)
- Institute of Biology and Medicine, Wuhan University of Science and Technology, Wuhan 430081, China
| | - Yeting Cui
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan 430081, China; (D.X.); (M.X.); (X.W.); (M.L.); (H.S.); (Y.C.)
- Institute of Biology and Medicine, Wuhan University of Science and Technology, Wuhan 430081, China
| | - Chen Chen
- Tumor Precision Diagnosis and Treatment Technology and Translational Medicine, Hubei Engineering Research Center, Zhongnan Hospital of Wuhan University, Wuhan 430071, China;
| | - Ziyu Jiang
- Tumor Precision Diagnosis and Treatment Technology and Translational Medicine, Hubei Engineering Research Center, Zhongnan Hospital of Wuhan University, Wuhan 430071, China;
| | - Fan Sun
- College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan 430081, China; (D.X.); (M.X.); (X.W.); (M.L.); (H.S.); (Y.C.)
- Institute of Biology and Medicine, Wuhan University of Science and Technology, Wuhan 430081, China
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2
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Amin MN, El-Far YM, El-Mowafy M, Elgaml A. Tazemetostat decreases β-catenin and CD13 protein expression in HEPG-2 and Hepatitis B virus-transfected HEPG-2 with decreased cell viability. Clin Epigenetics 2023; 15:180. [PMID: 37941056 PMCID: PMC10634085 DOI: 10.1186/s13148-023-01593-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Accepted: 10/30/2023] [Indexed: 11/10/2023] Open
Abstract
Hepatocellular carcinoma (HCC) is one of the global health concerns. Hepatitis B virus (HBV) is one of the major causes of HCC. Poor clinical outcome of HCC patients is attributed to a small population of cancer cells known as cancer stem cells (CSCs). In this work, we studied the effect of inhibiting the enhancer of zeste homologue 2 (EZH2), a histone methyltransferase known to be overexpressed in CSCs, using tazemetostat (Taz). The effect of Taz was assessed in the HCC cell line (HEPG2) and Hepatitis B virus-transfected HEPG2 (HBV/HEPG2) cells. MTT assay showed a significant decrease in HEPG2 cells viability after 48 h treatment with either 0.5, 1, 4 or 6 μM Taz. HEPG2 and HBV/HEPG2 cells were incubated with either 0.5 or 1 μM Taz for 48 h, and then, the cells and supernatants were collected for protein expression analysis of EZH2, CD13, epithelial cell adhesion molecule (EpCAM) and β-catenin using enzyme-linked immunosorbent assay (ELISA). Taz showed a significant dose-dependent inhibition of EZH2, CD13 and β-catenin in HEPG2 and HBV/HEPG2 cells. Also, EpCAM protein levels were significantly decreased in HBV/HEPG2 but not in HEPG2 cell line alone. Our results indicate that Taz inhibition of EZH2 leads to downregulation of β-catenin signaling and eventually decreased expression of CD13 and EpCAM, which are characteristic for CSCs. The present study suggests that Taz could be a promising treatment for HCC including HBV-induced HCC that might be used in combination with radio/chemotherapy to target CSCs and prevent tumor relapse.
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Affiliation(s)
- Mohamed N Amin
- Biochemistry Department, Faculty of Pharmacy, Mansoura University, Mansoura, 35516, Egypt
| | - Yousra M El-Far
- Biochemistry Department, Faculty of Pharmacy, Mansoura University, Mansoura, 35516, Egypt
| | - Mohammed El-Mowafy
- Microbiology and Immunology Department, Faculty of Pharmacy, Mansoura University, Mansoura, 35516, Egypt
| | - Abdelaziz Elgaml
- Microbiology and Immunology Department, Faculty of Pharmacy, Mansoura University, Mansoura, 35516, Egypt.
- Microbiology and Immunology Department, Faculty of Pharmacy, Horus University, New Damietta, 34518, Egypt.
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Understanding the versatile roles and applications of EpCAM in cancers: from bench to bedside. Exp Hematol Oncol 2022; 11:97. [PMID: 36369033 PMCID: PMC9650829 DOI: 10.1186/s40164-022-00352-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 10/26/2022] [Indexed: 11/13/2022] Open
Abstract
Epithelial cell adhesion molecule (EpCAM) functions not only in physiological processes but also participates in the development and progression of cancer. In recent decades, extensive efforts have been made to decipher the role of EpCAM in cancers. Great advances have been achieved in elucidating its structure, molecular functions, pathophysiological mechanisms, and clinical applications. Beyond its well-recognized role as a biomarker of cancer stem cells (CSCs) or circulating tumor cells (CTCs), EpCAM exhibits novel and promising value in targeted therapy. At the same time, the roles of EpCAM in cancer progression are found to be highly context-dependent and even contradictory in some cases. The versatile functional modules of EpCAM and its communication with other signaling pathways complicate the study of this molecule. In this review, we start from the structure of EpCAM and focus on communication with other signaling pathways. The impacts on the biology of cancers and the up-to-date clinical applications of EpCAM are also introduced and summarized, aiming to shed light on the translational prospects of EpCAM.
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Pan M, Kohlbauer V, Blancke Soares A, Schinke H, Huang Y, Kranz G, Quadt T, Hachmeister M, Gires O. Interactome analysis reveals endocytosis and membrane recycling of EpCAM during differentiation of embryonic stem cells and carcinoma cells. iScience 2021; 24:103179. [PMID: 34693227 PMCID: PMC8517208 DOI: 10.1016/j.isci.2021.103179] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 08/16/2021] [Accepted: 09/23/2021] [Indexed: 12/16/2022] Open
Abstract
Transmembrane epithelial cell adhesion molecule (EpCAM) is expressed in epithelia, carcinoma, teratoma, and embryonic stem cells (ESCs). EpCAM displays spatiotemporal patterning during embryogenesis, tissue morphogenesis, cell differentiation, and epithelial-to-mesenchymal transition (EMT) in carcinomas. Potential interactors of EpCAM were identified in murine F9 teratoma cells using a stable isotope labeling with amino acids in cell culture-based proteomic approach (n = 77, enrichment factor >3, p value ≤ 0.05). Kyoto Encyclopedia of Genes and Genomes and gene ontology terms revealed interactions with regulators of endosomal trafficking and membrane recycling, which were further validated for Rab5, Rab7, and Rab11. Endocytosis and membrane recycling of EpCAM were confirmed in mF9 cells, E14TG2α ESC, and Kyse30 carcinoma cells. Reduction of EpCAM during mesodermal differentiation and TGFβ-induced EMT correlated with enhanced endocytosis and block or reduction of recycling in ESCs and esophageal carcinoma cells. Hence, endocytosis and membrane recycling are means of regulation of EpCAM protein levels during differentiation of ESC and EMT induction in carcinoma cells.
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Affiliation(s)
- Min Pan
- Department of Otorhinolaryngology, The First Affiliated Hospital of Chongqing Medical University, Yuzhong District, Chongqing, China
| | - Vera Kohlbauer
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital, LMU Munich, Munich, Germany
| | - Alexandra Blancke Soares
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital, LMU Munich, Munich, Germany
| | - Henrik Schinke
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital, LMU Munich, Munich, Germany
| | - Yuanchi Huang
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital, LMU Munich, Munich, Germany
| | - Gisela Kranz
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital, LMU Munich, Munich, Germany
| | - Tanja Quadt
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital, LMU Munich, Munich, Germany
| | - Matthias Hachmeister
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital, LMU Munich, Munich, Germany
| | - Olivier Gires
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital, LMU Munich, Munich, Germany.,Clinical Cooperation Group "Personalized Radiotherapy in Head and Neck Cancer", Helmholtz Zentrum München, Neuherberg, Germany
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Pavšič M. Trop2 Forms a Stable Dimer with Significant Structural Differences within the Membrane-Distal Region as Compared to EpCAM. Int J Mol Sci 2021; 22:ijms221910640. [PMID: 34638982 PMCID: PMC8508679 DOI: 10.3390/ijms221910640] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Revised: 09/21/2021] [Accepted: 09/27/2021] [Indexed: 02/05/2023] Open
Abstract
Trop2 is a cell-surface transmembrane glycoprotein involved in the maintenance of epithelial tissue integrity and is an important carcinoma marker. It shares similar claudin-interaction capacity with its paralogue EpCAM, and both are implicated in signaling triggered by proteolytic cleavage within the ectodomain. However, the cell proliferation-regulating interactions with IGF-1, neuregulin-1, and α5β1 integrin appear to be Trop2-specific. To illuminate the structural differences between Trop2 and EpCAM, we report the first crystal structure of a Trop2 ectodomain dimer and compare it to the analogous part of EpCAM. While the overall fold of the two proteins is similar, the dimers differ. In Trop2, the inter-subunit contacts are more extensive than in EpCAM, and there are two major differences in the membrane-distal regions. The immunogenic N-terminal domain is in Trop2 almost colinear with the dimer interface plain and consequently more laterally exposed, and the cleft of yet unknown functionality between the two subunits is almost absent. Furthermore, the site of initial signaling-associated proteolytic cleavage in Trop2 is accessible in the dimeric state, while in EpCAM dimer destabilization is required. The structural differences highlight the divergent evolutionary path of the two proteins and pave the way for their structure-based utilization in therapy.
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Affiliation(s)
- Miha Pavšič
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna Pot 113, SI-1000 Ljubljana, Slovenia
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MAGI-1 PDZ2 Domain Blockade Averts Adenovirus Infection via Enhanced Proteolysis of the Apical Coxsackievirus and Adenovirus Receptor. J Virol 2021; 95:e0004621. [PMID: 33762416 DOI: 10.1128/jvi.00046-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Adenoviruses (AdVs) are etiological agents of gastrointestinal, heart, eye, and respiratory tract infections that can be lethal for immunosuppressed people. Many AdVs use the coxsackievirus and adenovirus receptor (CAR) as a primary receptor. The CAR isoform resulting from alternative splicing that includes the eighth exon, CAREx8, localizes to the apical surface of polarized epithelial cells and is responsible for the initiation of AdV infection. We have shown that the membrane level of CAREx8 is tightly regulated by two MAGI-1 PDZ domains, PDZ2 and PDZ4, resulting in increased or decreased AdV transduction, respectively. We hypothesized that targeting the interactions between the MAGI-1 PDZ2 domain and CAREx8 would decrease the apical CAREx8 expression level and prevent AdV infection. Decoy peptides that target MAGI-1 PDZ2 were synthesized (TAT-E6 and TAT-NET1). PDZ2 binding peptides decreased CAREx8 expression and reduced AdV transduction. CAREx8 degradation was triggered by the activation of the regulated intramembrane proteolysis (RIP) pathway through a disintegrin and metalloproteinase (ADAM17) and γ-secretase. Further analysis revealed that ADAM17 interacts directly with the MAGI-1 PDZ3 domain, and blocking the PDZ2 domain enhanced the accessibility of ADAM17 to the substrate (CAREx8). Finally, we validated the efficacy of TAT-PDZ2 peptides in protecting the epithelia from AdV transduction in vivo using a novel transgenic animal model. Our data suggest that TAT-PDZ2 binding peptides are novel anti-AdV molecules that act by enhanced RIP of CAREx8 and decreased AdV entry. This strategy has additional translational potential for targeting other viral receptors that have PDZ binding domains, such as the angiotensin-converting enzyme 2 receptor. IMPORTANCE Adenovirus is a common threat in immunosuppressed populations and military recruits. There are no currently approved treatments/prophylactic agents that protect from most AdV infections. Here, we developed peptide-based small molecules that can suppress AdV infection of polarized epithelia by targeting the AdV receptor, coxsackievirus and adenovirus receptor (CAREx8). The newly discovered peptides target a specific PDZ domain of the CAREx8-interacting protein MAGI-1 and decrease AdV transduction in multiple polarized epithelial models. Peptide-induced CAREx8 degradation is triggered by extracellular domain (ECD) shedding through ADAM17 followed by γ-secretase-mediated nuclear translocation of the C-terminal domain. The enhanced shedding of the CAREx8 ECD further protected the epithelium from AdV infection. Taken together, these novel molecules protect the epithelium from AdV infection. This approach may be applicable to the development of novel antiviral molecules against other viruses that use a receptor with a PDZ binding domain.
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Chen HN, Liang KH, Lai JK, Lan CH, Liao MY, Hung SH, Chuang YT, Chen KC, Tsuei WWF, Wu HC. EpCAM Signaling Promotes Tumor Progression and Protein Stability of PD-L1 through the EGFR Pathway. Cancer Res 2020; 80:5035-5050. [PMID: 32978170 DOI: 10.1158/0008-5472.can-20-1264] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Revised: 07/17/2020] [Accepted: 09/22/2020] [Indexed: 11/16/2022]
Abstract
Although epithelial cell adhesion molecule (EpCAM) has previously been shown to promote tumor progression, the underlying mechanisms remain largely unknown. Here, we report that the EGF-like domain I within the extracellular domain of EpCAM (EpEX) binds EGFR, activating both AKT and MAPK signaling to inhibit forkhead transcription factor O3a (FOXO3a) function and stabilize PD-L1 protein, respectively. Treatment with the EpCAM neutralizing antibody, EpAb2-6, inhibited AKT and FOXO3a phosphorylation, increased FOXO3a nuclear translocation, and upregulated high temperature requirement A2 (HtrA2) expression to promote apoptosis while decreasing PD-L1 protein levels to enhance the cytotoxic activity of CD8+ T cells. In vivo, EpAb2-6 markedly extended survival in mouse metastasis and orthotopic models of human colorectal cancer. The combination of EpAb2-6 with atezolizumab, an anti-PD-L1 antibody, almost completely eliminated tumors. Moreover, the number of CD8+ T cells in combination-treated tumors was increased compared with atezolizumab alone. Our findings suggest a new combination strategy for cancer immunotherapy in patients with EpCAM-expressing tumors. SIGNIFICANCE: This study shows that treatment with an EpCAM neutralizing antibody promotes apoptosis while decreasing PD-L1 protein to enhance cytotoxic activity of CD8+ T cells.
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Affiliation(s)
- Hao-Nien Chen
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan
| | - Kang-Hao Liang
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan
| | - Jun-Kai Lai
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan
| | - Chun-Hsin Lan
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan
| | - Mei-Ying Liao
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan
| | - Shao-Hsi Hung
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan
| | - Yi-Ting Chuang
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan
| | - Kai-Chi Chen
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan
| | - William Wei-Fu Tsuei
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan
| | - Han-Chung Wu
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan.
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Fagotto F, Aslemarz A. EpCAM cellular functions in adhesion and migration, and potential impact on invasion: A critical review. Biochim Biophys Acta Rev Cancer 2020; 1874:188436. [PMID: 32976980 DOI: 10.1016/j.bbcan.2020.188436] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 09/19/2020] [Accepted: 09/19/2020] [Indexed: 12/14/2022]
Abstract
EpCAM has long been known as a cell surface protein highly expressed in carcinomas. It has since become one of the key cancer biomarkers. Despite its high fame, its actual role in cancer development is still controversial. Beyond a flurry of correlative studies, which point either to a positive or a negative link with tumour progression, there has been surprisingly few studies on the actual cellular mechanisms of EpCAM and on their functional consequences. Clearly, EpCAM plays multiple important roles, in cell proliferation as well as in cell adhesion and migration. The two latter functions, directly relevant for metastasis, are the focus of this review. We attempt here to bring together the available experimental data to build a global coherent view of EpCAM functions. We also include in this overview EpCAM2/Trop2, the close relative of EpCAM. At the core of EpCAM (and EpCAM2/Trop2) function stands the ability to repress contractility of the actomyosin cell cortex. This activity appears to involve direct inhibition by EpCAM of members of the novel PKC family and of a specific downstream PKD-Erk cascade. We will discuss how this activity can result in a variety of adhesive and migratory phenotypes, thus potentially explaining at least part of the apparent inconsistencies between different studies. The picture remains fragmented, and we will highlight some of the conflicting evidence and the many unsolved issues, starting with the controversy around its original description as a cell-cell adhesion molecule.
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Affiliation(s)
- François Fagotto
- CRBM, University of Montpellier and CNRS, Montpellier 34293, France.
| | - Azam Aslemarz
- CRBM, University of Montpellier and CNRS, Montpellier 34293, France; Department of Biology, McGill University, Montreal, QC H3A1B1, Canada
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Fagotto F. EpCAM as Modulator of Tissue Plasticity. Cells 2020; 9:E2128. [PMID: 32961790 PMCID: PMC7563481 DOI: 10.3390/cells9092128] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 08/24/2020] [Accepted: 09/14/2020] [Indexed: 01/01/2023] Open
Abstract
The Epithelial Cell Adhesion Molecule or EpCAM is a well-known marker highly expressed in carcinomas and showing a strong correlation with poor cancer prognosis. While its name relates to its proposed function as a cell adhesion molecule, EpCAM has been shown to have various signalling functions. In particular, it has been identified as an important positive regulator of cell adhesion and migration, playing an essential role in embryonic morphogenesis as well as intestinal homeostasis. This activity is not due to its putative adhesive function, but rather to its ability to repress myosin contractility by impinging on a PKC signalling cascade. This mechanism confers EpCAM the unique property of favouring tissue plasticity. I review here the currently available data, comment on possible connections with other properties of EpCAM, and discuss the potential significance in the context of cancer invasion.
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Affiliation(s)
- François Fagotto
- CRBM, University of Montpellier and CNRS, 34293 Montpellier, France
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Gires O, Pan M, Schinke H, Canis M, Baeuerle PA. Expression and function of epithelial cell adhesion molecule EpCAM: where are we after 40 years? Cancer Metastasis Rev 2020; 39:969-987. [PMID: 32507912 PMCID: PMC7497325 DOI: 10.1007/s10555-020-09898-3] [Citation(s) in RCA: 141] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
EpCAM (epithelial cell adhesion molecule) was discovered four decades ago as a tumor antigen on colorectal carcinomas. Owing to its frequent and high expression on carcinomas and their metastases, EpCAM serves as a prognostic marker, a therapeutic target, and an anchor molecule on circulating and disseminated tumor cells (CTCs/DTCs), which are considered the major source for metastatic cancer cells. Today, EpCAM is reckoned as a multi-functional transmembrane protein involved in the regulation of cell adhesion, proliferation, migration, stemness, and epithelial-to-mesenchymal transition (EMT) of carcinoma cells. To fulfill these functions, EpCAM is instrumental in intra- and intercellular signaling as a full-length molecule and following regulated intramembrane proteolysis, generating functionally active extra- and intracellular fragments. Intact EpCAM and its proteolytic fragments interact with claudins, CD44, E-cadherin, epidermal growth factor receptor (EGFR), and intracellular signaling components of the WNT and Ras/Raf pathways, respectively. This plethora of functions contributes to shaping intratumor heterogeneity and partial EMT, which are major determinants of the clinical outcome of carcinoma patients. EpCAM represents a marker for the epithelial status of primary and systemic tumor cells and emerges as a measure for the metastatic capacity of CTCs. Consequentially, EpCAM has reclaimed potential as a prognostic marker and target on primary and systemic tumor cells.
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Affiliation(s)
- Olivier Gires
- Department of Otorhinolaryngology, University Hospital, LMU Munich, Marchioninistr. 15, 81377, Munich, Germany.
- Clinical Cooperation Group "Personalized Radiotherapy in Head and Neck Cancer", Helmholtz Zentrum, Neuherberg, Germany.
| | - Min Pan
- Department of Otorhinolaryngology, University Hospital, LMU Munich, Marchioninistr. 15, 81377, Munich, Germany
- Department of Otorhinolaryngology, The First Affiliated Hospital of Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing, 400016, China
| | - Henrik Schinke
- Department of Otorhinolaryngology, University Hospital, LMU Munich, Marchioninistr. 15, 81377, Munich, Germany
| | - Martin Canis
- Department of Otorhinolaryngology, University Hospital, LMU Munich, Marchioninistr. 15, 81377, Munich, Germany
| | - Patrick A Baeuerle
- Institute for Immunology, LMU Munich, Grosshadernerstr. 9, 82152 Planegg, Martinsried, Germany
- MPM Capital, Cambridge MA, 450 Kendall Street, Cambridge, MA, 02142, USA
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Gaber A, Lenarčič B, Pavšič M. Current View on EpCAM Structural Biology. Cells 2020; 9:cells9061361. [PMID: 32486423 PMCID: PMC7349879 DOI: 10.3390/cells9061361] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 05/28/2020] [Accepted: 05/29/2020] [Indexed: 02/06/2023] Open
Abstract
EpCAM, a carcinoma cell-surface marker protein and a therapeutic target, has been primarily addressed as a cell adhesion molecule. With regard to recent discoveries of its role in signaling with implications in cell proliferation and differentiation, and findings contradicting a direct role in mediating adhesion contacts, we provide a comprehensive and updated overview on the available structural data on EpCAM and interpret it in the light of recent reports on its function. First, we describe the structure of extracellular part of EpCAM, both as a subunit and part of a cis-dimer which, according to several experimental observations, represents a biologically relevant oligomeric state. Next, we provide a thorough evaluation of reports on EpCAM as a homophilic cell adhesion molecule with a structure-based explanation why direct EpCAM participation in cell–cell contacts is highly unlikely. Finally, we review the signaling aspect of EpCAM with focus on accessibility of signaling-associated cleavage sites.
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Affiliation(s)
- Aljaž Gaber
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (A.G.); (B.L.)
| | - Brigita Lenarčič
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (A.G.); (B.L.)
- Department of Biochemistry, Molecular and Structural Biology, Jožef Stefan Institute, SI-1000 Ljubljana, Slovenia
| | - Miha Pavšič
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (A.G.); (B.L.)
- Correspondence: ; Tel.: +386-1-479-8550
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Effects of Delta-Like Noncanonical Notch Ligand 1 Expression of Human Fetal Liver Hepatoblasts on Hematopoietic Progenitors. Stem Cells Int 2019; 2019:7916275. [PMID: 31011334 PMCID: PMC6442310 DOI: 10.1155/2019/7916275] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 12/14/2018] [Accepted: 01/09/2019] [Indexed: 02/01/2023] Open
Abstract
Although the hepatic and hematopoietic progenitors of the liver are well characterized, the interactions between these two lineages remain mostly elusive. Hepatoblasts express delta-like noncanonical Notch ligand 1 (Dlk1), whose cleaved extracellular domain can become a soluble protein. We assessed the effects of DLK1 gene expression knockdown in cultures of total fetal liver cells. Furthermore, we separated Dlk1+ hepatoblasts from the total liver cell fraction and investigated effects of direct cell contact. Dlk1− cells were cultured either without Dlk1+ hepatoblasts, in direct contact with hepatoblasts, or separated from hepatoblasts by a porous membrane in inserts to inhibit cell contact but allow free exchange of molecules. Expression of the hepatic and hematopoietic genes, colony forming unit potential of various hematopoietic progenitors, and cell numbers and types were investigated. We found that DLK1 knockdown in total fetal liver cell cultures decreased total cell numbers. The expression of hepatic progenitor genes and mature hematopoietic genes was affected. Hematopoietic BFU-E and CFU-GM colony numbers were reduced significantly. The depletion of Dlk1+ hepatoblasts in culture decreased the potential of all hematopoietic progenitors to form colonies of all types and reduced the percentage of mature hematopoietic cells. The addition of hepatoblasts in inserts to Dlk1− cells further decreased the potential to form the CFU-GM and CFU-GEMM colonies and the percentage of mature hematopoietic cells but increased total cell numbers. Conclusively, direct contact of Dlk1 supports hematopoietic progenitor expansion and functionality that cannot be reconstituted in coculture without direct cell contact.
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13
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Schmelzer E. Hepatic progenitors of the fetal liver: Interactions with hematopoietic stem cells. Differentiation 2019; 106:9-14. [PMID: 30826473 DOI: 10.1016/j.diff.2019.02.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 02/18/2019] [Accepted: 02/20/2019] [Indexed: 12/29/2022]
Abstract
The aim of this review is to summarize and give an overview on the findings of signaling between hepatic and hematopoietic progenitors of the liver. To date, there are not many findings published in the field, and the aim of this review is to cover all current publications in this area. The liver is the main site of hematopoiesis during fetal development. However, little is known about how hepatic and other non-hematopoietic progenitors potentially influence hematopoiesis and vice versa. The concurrent peaks of hepatic and hematopoietic progenitor proliferation during development indicate interactions that could possibly be mediated through cell-cell contact, extracellular matrices, cytokines and growth factors, or other signaling molecules. For example, hepatic progenitors, such as hepatic stem cells and hepatoblasts, possess characteristic surface markers that can be cleaved, giving rise to fragments of various lengths. A surface molecule of hepatoblasts has been demonstrated to play an essential role in hematopoiesis. Particularly, these effects on hematopoiesis were distinct, depending on whether it was membrane-bound or cleaved. In this review, the various hepatic and hematopoietic progenitor cell types are concisely described, and the current findings of their potential interactions are summarized.
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Affiliation(s)
- Eva Schmelzer
- Department of Surgery, McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, 3025 East Carson Street, Pittsburgh, PA 15203, USA.
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14
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Huang Y, Chanou A, Kranz G, Pan M, Kohlbauer V, Ettinger A, Gires O. Membrane-associated epithelial cell adhesion molecule is slowly cleaved by γ-secretase prior to efficient proteasomal degradation of its intracellular domain. J Biol Chem 2018; 294:3051-3064. [PMID: 30598504 DOI: 10.1074/jbc.ra118.005874] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 12/20/2018] [Indexed: 12/27/2022] Open
Abstract
Regulated intramembrane proteolysis (RIP) is a key mechanism for activating transmembrane proteins such as epithelial cell adhesion molecule (EpCAM) for cellular signaling and degradation. EpCAM is highly expressed in carcinomas and progenitor and embryonic stem cells and is involved in the regulation of cell adhesion, proliferation, and differentiation. Strictly sequential cleavage of EpCAM through RIP involves initial shedding of the extracellular domain by α-secretase (ADAM) and β-secretase (BACE) sheddases, generating a membrane-tethered C-terminal fragment EpCTF. Subsequently, the rate-limiting γ-secretase complex catalyzes intramembrane cleavage of EpCTF, generating an extracellular EpCAM-Aβ-like fragment and an intracellular EpICD fragment involved in nuclear signaling. Here, we have combined biochemical approaches with live-cell imaging of fluorescent protein tags to investigate the kinetics of γ-secretase-mediated intramembrane cleavage of EpCTF. We demonstrate that γ-secretase-mediated proteolysis of exogenously and endogenously expressed EpCTF is a slow process with a 50% protein turnover in cells ranging from 45 min to 5.5 h. The slow cleavage was dictated by γ-secretase activity and not by EpCTF species, as indicated by cross-species swapping experiments. Furthermore, both human and murine EpICDs generated from EpCTF by γ-secretase were degraded efficiently (94-99%) by the proteasome. Hence, proteolytic cleavage of EpCTF is a comparably slow process, and EpICD generation does not appear to be suited for rapidly transducing extracellular cues into nuclear signaling, but appears to provide steady signals that can be further controlled through efficient proteasomal degradation. Our approach provides an unbiased bioassay to investigate proteolytic processing of EpCTF in single living cells.
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Affiliation(s)
- Yuanchi Huang
- From the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center, Ludwig-Maximilians-University, Munich, Marchioninistrasse 15, 81377 Munich, Germany, .,the Department of Spinal Surgery, Honghui Hospital, Xi'an Jiaotong University, Xi'an 710054, China
| | - Anna Chanou
- From the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center, Ludwig-Maximilians-University, Munich, Marchioninistrasse 15, 81377 Munich, Germany
| | - Gisela Kranz
- From the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center, Ludwig-Maximilians-University, Munich, Marchioninistrasse 15, 81377 Munich, Germany
| | - Min Pan
- From the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center, Ludwig-Maximilians-University, Munich, Marchioninistrasse 15, 81377 Munich, Germany
| | - Vera Kohlbauer
- From the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center, Ludwig-Maximilians-University, Munich, Marchioninistrasse 15, 81377 Munich, Germany
| | - Andreas Ettinger
- the Institute of Epigenetics and Stem Cells, Marchioninistrasse 25, 81377 München, Germany, and
| | - Olivier Gires
- From the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center, Ludwig-Maximilians-University, Munich, Marchioninistrasse 15, 81377 Munich, Germany, .,the Clinical Cooperation Group Personalized Radiotherapy of Head and Neck Tumors, Helmholtz Zentrum München, 85764 Neuherberg, Germany
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15
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Huang L, Yang Y, Yang F, Liu S, Zhu Z, Lei Z, Guo J. Functions of EpCAM in physiological processes and diseases (Review). Int J Mol Med 2018; 42:1771-1785. [PMID: 30015855 PMCID: PMC6108866 DOI: 10.3892/ijmm.2018.3764] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Accepted: 07/04/2018] [Indexed: 12/14/2022] Open
Abstract
EpCAM (epithelial cell adhesion molecule) is a type I transmembrane glycoprotein, which was originally identified as a tumor-associated antigen due to its high expression level in rapidly growing epithelial tumors. Germ line mutations of the human EpCAM gene have been indicated as the cause of congenital tufting enteropathy. Previous studies based on cell models have revealed that EpCAM contributes to various biological processes including cell adhesion, signaling, migration and proliferation. Due to the previous lack of genetic animal models, the in vivo functions of EpCAM remain largely unknown. However, EpCAM genetic animal models have recently been generated, and are useful for understanding the functions of EpCAM. The authors here briefly review the functions and mechanisms of EpCAM in physiological processes and different diseases.
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Affiliation(s)
- Li Huang
- Guangdong Metabolic Disease Research Center of Integrated Chinese and Western Medicine, Guangdong Pharmaceutical University, Guangzhou Higher Education Mega Center, Guangzhou, Guangdong 510006, P.R. China
| | - Yanhong Yang
- The First Affiliated Hospital, School of Clinical Medicine, Guangdong Pharmaceutical University, Guangzhou, Guangdong 510080, P.R. China
| | - Fei Yang
- Guangdong Metabolic Disease Research Center of Integrated Chinese and Western Medicine, Guangdong Pharmaceutical University, Guangzhou Higher Education Mega Center, Guangzhou, Guangdong 510006, P.R. China
| | - Shaomin Liu
- Guangdong Metabolic Disease Research Center of Integrated Chinese and Western Medicine, Guangdong Pharmaceutical University, Guangzhou Higher Education Mega Center, Guangzhou, Guangdong 510006, P.R. China
| | - Ziqin Zhu
- Guangdong Metabolic Disease Research Center of Integrated Chinese and Western Medicine, Guangdong Pharmaceutical University, Guangzhou Higher Education Mega Center, Guangzhou, Guangdong 510006, P.R. China
| | - Zili Lei
- Guangdong Metabolic Disease Research Center of Integrated Chinese and Western Medicine, Guangdong Pharmaceutical University, Guangzhou Higher Education Mega Center, Guangzhou, Guangdong 510006, P.R. China
| | - Jiao Guo
- Guangdong Metabolic Disease Research Center of Integrated Chinese and Western Medicine, Guangdong Pharmaceutical University, Guangzhou Higher Education Mega Center, Guangzhou, Guangdong 510006, P.R. China
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16
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Tretter JY, Schorpp K, Luxenburger E, Trambauer J, Steiner H, Hadian K, Gires O, Niessing D. A high-content screen for small-molecule regulators of epithelial cell-adhesion molecule (EpCAM) cleavage yields a robust inhibitor. J Biol Chem 2018; 293:8994-9005. [PMID: 29700109 DOI: 10.1074/jbc.ra118.002776] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 04/20/2018] [Indexed: 12/30/2022] Open
Abstract
Epithelial cell-adhesion molecule (EpCAM) is a transmembrane protein that regulates cell cycle progression and differentiation and is overexpressed in many carcinomas. The EpCAM-induced mitogenic cascade is activated via regulated intramembrane proteolysis (RIP) of EpCAM by ADAM and γ-secretases, generating the signaling-active intracellular domain EpICD. Because of its expression pattern and molecular function, EpCAM is a valuable target in prognostic and therapeutic approaches for various carcinomas. So far, several immunotherapeutic strategies have targeted the extracellular domain of EpCAM. However, targeting the intracellular signaling cascade of EpCAM holds promise for specifically interfering with EpCAM's proliferation-stimulating signaling cascade. Here, using a yellow fluorescence protein-tagged version of the C-terminal fragment of EpCAM, we established a high-content screening (HCS) of a small-molecule compound library (n = 27,280) and characterized validated hits that target EpCAM signaling. In total, 128 potential inhibitors were initially identified, of which one compound with robust inhibitory effects on RIP of EpCAM was analyzed in greater detail. In summary, our study demonstrates that the development of an HCS for small-molecule inhibitors of the EpCAM signaling pathway is feasible. We propose that this approach may also be useful for identifying chemical compounds targeting other disorders involving membrane cleavage-dependent signaling pathways.
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Affiliation(s)
| | - Kenji Schorpp
- the Assay Development and Screening Platform, Institute for Molecular Toxicology and Pharmacology, Helmholtz Zentrum München, German Center for Environmental Health, 85764 Neuherberg, Germany
| | - Elke Luxenburger
- the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center and
| | - Johannes Trambauer
- the Biomedical Center, Metabolic Biochemistry, Ludwig-Maximilians-University Munich, 80539 Munich, Germany
| | - Harald Steiner
- the Biomedical Center, Metabolic Biochemistry, Ludwig-Maximilians-University Munich, 80539 Munich, Germany.,the German Center for Neurodegenerative Diseases, 81377 Munich, Germany, and
| | - Kamyar Hadian
- the Assay Development and Screening Platform, Institute for Molecular Toxicology and Pharmacology, Helmholtz Zentrum München, German Center for Environmental Health, 85764 Neuherberg, Germany
| | - Olivier Gires
- the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center and
| | - Dierk Niessing
- From the Institute of Structural Biology and .,the Institute of Pharmaceutical Biotechnology, Ulm University, 89081 Ulm, Germany
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17
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Spatiotemporal patterning of EpCAM is important for murine embryonic endo- and mesodermal differentiation. Sci Rep 2018; 8:1801. [PMID: 29379062 PMCID: PMC5789065 DOI: 10.1038/s41598-018-20131-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 01/15/2018] [Indexed: 01/07/2023] Open
Abstract
Epithelial cell adhesion molecule EpCAM is expressed in pluripotent embryonic stem cells (ESC) in vitro, but is repressed in differentiated cells, except epithelia and carcinomas. Molecular functions of EpCAM, possibly imposing such repression, were primarily studied in malignant cells and might not apply to non-pathologic differentiation. Here, we comprehensively describe timing and rationale for EpCAM regulation in early murine gastrulation and ESC differentiation using single cell RNA-sequencing datasets, in vivo and in vitro models including CRISPR-Cas9-engineered ESC-mutants. We demonstrate expression of EpCAM in inner cell mass, epiblast, primitive/visceral endoderm, and strict repression in the most primitive, nascent Flk1+ mesoderm progenitors at E7.0. Selective expression of EpCAM was confirmed at mid-gestation and perinatal stages. The rationale for strict patterning was studied in ESC differentiation. Gain/loss-of-function demonstrated supportive functions of EpCAM in achieving full pluripotency and guided endodermal differentiation, but repressive functions in mesodermal differentiation as exemplified with cardiomyocyte formation. We further identified embryonic Ras (ERas) as novel EpCAM interactor of EpCAM and an EpCAM/ERas/AKT axis that is instrumental in differentiation regulation. Hence, spatiotemporal patterning of EpCAM at the onset of gastrulation, resulting in early segregation of interdependent EpCAM+ endodermal and EpCAM-/vimentin+ mesodermal clusters represents a novel regulatory feature during ESC differentiation.
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18
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Gerlach JC, Foka HG, Thompson RL, Gridelli B, Schmelzer E. Epithelial cell adhesion molecule fragments and signaling in primary human liver cells. J Cell Physiol 2017; 233:4841-4851. [PMID: 29150960 DOI: 10.1002/jcp.26286] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 11/14/2017] [Indexed: 01/15/2023]
Abstract
Epithelial Cell Adhesion Molecule (EpCAM), or CD326, is a trans-membrane glycoprotein expressed by multiple normal epithelia as well as carcinoma. Human hepatic stem cells and bile duct epithelium of the liver are EpCAM positive. In tumor cell lines, its intracellular domain can be released after cleavage of the extracellular domain. Within the cell nucleus, it induces cell proliferation, but cleavage depends on cell contact. Fragments of various lengths have been described in tumor cells. Despite its described important role in proliferation in tumor cells, there is not much known about the expression and role of EpCAM fragments in primary human liver cells. Here, we demonstrate that EpCAM protein fragments and function are considerable different between tumor cells, normal fetal and adult liver cells. Contrary to previously reported findings in tumor cells, gene knockdown or treatment with an inhibitor of the cleavage enzyme ADAM17 (TACE) rather increased cell numbers in primary human fetal liver-derived EpCAM-positive cells. EpCAM fragment sizes were not affected by treatment with inhibitor. Knockdown of EPCAM gene expression by siRNA in sorted cells did not significantly affect proliferation-associated genes or cell numbers. The intracellular domain could not be detected within cell nuclei of fetal and adult liver cells. In conclusion, signaling through the intracellular domain of EpCAM appears to be a mechanism that induces proliferation specifically in tumorigenic cells but not in normal primary EpCAM-positive liver cells.
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Affiliation(s)
- Jörg C Gerlach
- Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania.,Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Hubert G Foka
- University of Pittsburgh Medical Center, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Robert L Thompson
- University of Pittsburgh Medical Center, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Bruno Gridelli
- University of Pittsburgh Medical Center, University of Pittsburgh, Pittsburgh, Pennsylvania.,Department of Surgery, ISMETT-Istituto Mediterraneo per i Trapianti e Terapie ad Alta Specializzazione, UPMC Italy, Palermo, Italy
| | - Eva Schmelzer
- Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania
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19
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Regulated intramembrane proteolysis: emergent role in cell signalling pathways. Biochem Soc Trans 2017; 45:1185-1202. [PMID: 29079648 DOI: 10.1042/bst20170002] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 08/27/2017] [Accepted: 08/29/2017] [Indexed: 12/12/2022]
Abstract
Receptor signalling events including those initiated following activation of cytokine and growth factor receptors and the well-characterised death receptors (tumour necrosis factor receptor, type 1, FasR and TRAIL-R1/2) are initiated at the cell surface through the recruitment and formation of intracellular multiprotein signalling complexes that activate divergent signalling pathways. Over the past decade, research studies reveal that many of these receptor-initiated signalling events involve the sequential proteolysis of specific receptors by membrane-bound proteases and the γ-secretase protease complexes. Proteolysis enables the liberation of soluble receptor ectodomains and the generation of intracellular receptor cytoplasmic domain fragments. The combined and sequential enzymatic activity has been defined as regulated intramembrane proteolysis and is now a fundamental signal transduction process involved in the termination or propagation of receptor signalling events. In this review, we discuss emerging evidence for a role of the γ-secretase protease complexes and regulated intramembrane proteolysis in cell- and immune-signalling pathways.
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20
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An anti-EpCAM antibody EpAb2-6 for the treatment of colon cancer. Oncotarget 2016; 6:24947-68. [PMID: 26317650 PMCID: PMC4694806 DOI: 10.18632/oncotarget.4453] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 07/24/2015] [Indexed: 02/07/2023] Open
Abstract
Epithelial cell adhesion molecule (EpCAM) is known to be overexpressed in epithelial cancers associated with enhanced malignant potential, particularly colorectal carcinoma (CRC) and head and neck squamous cell carcinoma (HNSCC). However, it is unknown whether progression of malignance can be directly inhibited by targeting EpCAM. Here, we have generated five novel monoclonal antibodies (mAbs) against EpCAM. One of these anti-EpCAM mAbs, EpAb2-6, was found to induce cancer cell apoptosis in vitro, inhibit tumor growth, and prolong the overall survival of both a pancreatic cancer metastatic mouse model and mice with human colon carcinoma xenografts. EpAb2-6 also increases the therapeutic efficacy of irinotecan, fluorouracil, and leucovorin (IFL) therapy in a colon cancer animal model and gemcitabine therapy in a pancreatic cancer animal model. Furthermore, EpAb2-6, which binds to positions Y95 and D96 of the EGF-II/TY domain of EpCAM, inhibits production of EpICD, thereby decreasing its translocation and subsequent signal activation. Collectively, our results indicate that the novel anti-EpCAM mAb can potentially be used for cancer-targeted therapy.
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21
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Tsaktanis T, Kremling H, Pavšič M, von Stackelberg R, Mack B, Fukumori A, Steiner H, Vielmuth F, Spindler V, Huang Z, Jakubowski J, Stoecklein NH, Luxenburger E, Lauber K, Lenarčič B, Gires O. Cleavage and cell adhesion properties of human epithelial cell adhesion molecule (HEPCAM). J Biol Chem 2015; 290:24574-91. [PMID: 26292218 DOI: 10.1074/jbc.m115.662700] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Indexed: 12/14/2022] Open
Abstract
Human epithelial cell adhesion molecule (HEPCAM) is a tumor-associated antigen frequently expressed in carcinomas, which promotes proliferation after regulated intramembrane proteolysis. Here, we describe extracellular shedding of HEPCAM at two α-sites through a disintegrin and metalloprotease (ADAM) and at one β-site through BACE1. Transmembrane cleavage by γ-secretase occurs at three γ-sites to generate extracellular Aβ-like fragments and at two ϵ-sites to release human EPCAM intracellular domain HEPICD, which is efficiently degraded by the proteasome. Mapping of cleavage sites onto three-dimensional structures of HEPEX cis-dimer predicted conditional availability of α- and β-sites. Endocytosis of HEPCAM warrants acidification in cytoplasmic vesicles to dissociate protein cis-dimers required for cleavage by BACE1 at low pH values. Intramembrane cleavage sites are accessible and not part of the structurally important transmembrane helix dimer crossing region. Surprisingly, neither chemical inhibition of cleavage nor cellular knock-out of HEPCAM using CRISPR-Cas9 technology impacted the adhesion of carcinoma cell lines. Hence, a direct function of HEPCAM as an adhesion molecule in carcinoma cells is not supported and appears to be questionable.
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Affiliation(s)
- Thanos Tsaktanis
- From the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center
| | - Heidi Kremling
- From the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center
| | - Miha Pavšič
- the Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna Pot 113, SI-1000 Ljubljana, Slovenia
| | - Ricarda von Stackelberg
- From the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center
| | - Brigitte Mack
- From the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center
| | - Akio Fukumori
- the DZNE-German Center for Neurodegenerative Diseases, Feodor-Lynen-Strasse 17, 81377 Munich, Germany
| | - Harald Steiner
- the DZNE-German Center for Neurodegenerative Diseases, Feodor-Lynen-Strasse 17, 81377 Munich, Germany, Biomedical Center, Biochemistry
| | | | | | - Zhe Huang
- From the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center
| | - Jasmine Jakubowski
- From the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center, the Munich Center for Neurosciences, LMU Biocenter, AMGEN Scholars Programme, Ludwig-Maximilians-Universität Munich, Grosshaderner Strasse 2, 82152 Planegg-Martinsried, Germany, and
| | - Nikolas H Stoecklein
- the Department for General, Visceral, and Pediatric Surgery, University Hospital and Medical Faculty of the Heinrich-Heine University Düsseldorf, Moorenstrasse 5, D-40225 Düsseldorf, Germany
| | - Elke Luxenburger
- From the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center
| | - Kirsten Lauber
- Clinic for Radiotherapy and Radiation Oncology, and the Clinical Cooperation Group Personalized Radiotherapy of Head and Neck Tumors, Ludwig-Maximilians-University of Munich, Marchioninistrasse 15, 81377 Munich, Germany
| | - Brigita Lenarčič
- the Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna Pot 113, SI-1000 Ljubljana, Slovenia
| | - Olivier Gires
- From the Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center,
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22
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Hepatitis B virus X protein induces EpCAM expression via active DNA demethylation directed by RelA in complex with EZH2 and TET2. Oncogene 2015; 35:715-26. [PMID: 25893293 PMCID: PMC4615262 DOI: 10.1038/onc.2015.122] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 03/09/2015] [Accepted: 03/10/2015] [Indexed: 12/16/2022]
Abstract
Chronic hepatitis B virus (HBV) infection is a major risk factor for developing hepatocellular carcinoma (HCC), and HBV X protein (HBx) acts as cofactor in hepatocarcinogenesis. In liver tumors from animals modeling HBx- and HBV-mediated hepatocarcinogenesis, downregulation of chromatin regulating proteins SUZ12 and ZNF198 induces expression of several genes, including epithelial cell adhesion molecule (EpCAM). EpCAM upregulation occurs in HBV-mediated HCCs and hepatic cancer stem cells, by a mechanism not understood. Herein we demonstrate HBx induces EpCAM expression via active DNA demethylation. In hepatocytes, EpCAM is silenced by polycomb repressive complex 2 (PRC2) and ZNF198/LSD1/Co-REST/HDAC1 chromatin-modifying complexes. Cells with stable knockdown of SUZ12, an essential PRC2 subunit, upon HBx expression demethylate a CpG dinucleotide located adjacent to NF-κB/RelA half-site. This NF-κB/RelA site is in a CpG island downstream from EpCAM transcriptional start site (TSS). Chromatin immunoprecipitation (ChIP) assays demonstrate HBx-dependent RelA occupancy of NF-κB half-site, whereas RelA knockdown suppresses CpG demethylation and EpCAM expression. Tumor necrosis factor-α activates RelA, propagating demethylation to nearby CpG sites, shown by sodium bisulfite sequencing. RelA-dependent demethylation occurring upon HBx expression requires methyltrasferase EZH2, TET2 a key factor in cytosine demethylation and inactive DNMT3L, shown by knockdown assays and sodium bisulfite sequencing. Co-immunoprecipitations and sequential ChIP assays demonstrate that RelA in the presence of HBx forms a complex with EZH2, TET2 and DNMT3L, although the role of DNMT3L remains to be understood. Interestingly, the human EpCAM gene also has a CpG island downstream from its TSS, and a NF-κB-binding site flanked by CpGs. HepG2 cells derived from human HCC exhibit demethylation of these NF-κB-flanking CpG sites, and HBV replication propagates demethylation to nearby CpG sites. DLK1, another PRC2 target gene, also upregulated in HBV-mediated HCCs, is demethylated in liver tumors at CpG dinucleotides flanking the NF-κB-binding sequence, supporting that this active DNA demethylation mechanism functions during oncogenic transformation.
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23
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Dollé L, Theise ND, Schmelzer E, Boulter L, Gires O, van Grunsven LA. EpCAM and the biology of hepatic stem/progenitor cells. Am J Physiol Gastrointest Liver Physiol 2015; 308:G233-50. [PMID: 25477371 PMCID: PMC4329473 DOI: 10.1152/ajpgi.00069.2014] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Epithelial cell adhesion molecule (EpCAM) is a transmembrane glycoprotein, which is frequently and highly expressed on carcinomas, tumor-initiating cells, selected tissue progenitors, and embryonic and adult stem cells. During liver development, EpCAM demonstrates a dynamic expression, since it can be detected in fetal liver, including cells of the parenchyma, whereas mature hepatocytes are devoid of EpCAM. Liver regeneration is associated with a population of EpCAM-positive cells within ductular reactions, which gradually lose the expression of EpCAM along with maturation into hepatocytes. EpCAM can be switched on and off through a wide panel of strategies to fine-tune EpCAM-dependent functional and differentiative traits. EpCAM-associated functions relate to cell-cell adhesion, proliferation, maintenance of a pluripotent state, regulation of differentiation, migration, and invasion. These functions can be conferred by the full-length protein and/or EpCAM-derived fragments, which are generated upon regulated intramembrane proteolysis. Control by EpCAM therefore not only depends on the presence of full-length EpCAM at cellular membranes but also on varying rates of the formation of EpCAM-derived fragments that have their own regulatory properties and on changes in the association of EpCAM with interaction partners. Thus spatiotemporal localization of EpCAM in immature liver progenitors, transit-amplifying cells, and mature liver cells will decisively impact the regulation of EpCAM functions and might be one of the triggers that contributes to the adaptive processes in stem/progenitor cell lineages. This review will summarize EpCAM-related molecular events and how they relate to hepatobiliary differentiation and regeneration.
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Affiliation(s)
- Laurent Dollé
- Department of Biomedical Sciences, Liver Cell Biology Lab, Vrije Universiteit Brussel, Brussels, Belgium;
| | - Neil D. Theise
- 2Departments of Pathology and Medicine, Beth Israel Medical Center of Albert Einstein College of Medicine, New York, New York;
| | - Eva Schmelzer
- 3McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania;
| | - Luke Boulter
- 4Medical Research Council Human Genetics Unit, Institute for Genetics and Molecular Medicine, Edinburgh, Scotland; and
| | - Olivier Gires
- 5Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center, Ludwig-Maximilians-University of Munich, Munich, Germany
| | - Leo A. van Grunsven
- 1Department of Biomedical Sciences, Liver Cell Biology Lab, Vrije Universiteit Brussel, Brussels, Belgium;
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Gires O, Stoecklein NH. Dynamic EpCAM expression on circulating and disseminating tumor cells: causes and consequences. Cell Mol Life Sci 2014; 71:4393-402. [PMID: 25103341 PMCID: PMC11113679 DOI: 10.1007/s00018-014-1693-1] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 07/22/2014] [Accepted: 07/24/2014] [Indexed: 12/19/2022]
Abstract
Formation of metastasis is the most important and lethal step in cancer progression. Circulating and disseminated cancer cells (CTCs/DTCs) in blood and bone marrow are considered as potential metastases-inducing cells. Their detection and characterization has, therefore, become a field of major interest in translational and clinical research in oncology. The main strategy to detect these cells relies thus far on the epithelial characteristics of carcinoma cells and epithelial cell adhesion molecule (EpCAM) represents the most commonly used epithelial marker to capture CTCs/DTCs. Recent data, however, demonstrated a dynamic expression of EpCAM associated with a loss during epithelial-to-mesenchymal transition. The present review summarizes the potential mechanisms and reasons for a dynamic expression of EpCAM.
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Affiliation(s)
- Olivier Gires
- Department of Otorhinolaryngology, Head and Neck Surgery, Grosshadern Medical Center, Ludwig-Maximilians-University of Munich, Marchioninistr. 15, 81377, Munich, Germany,
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Pavšič M, Gunčar G, Djinović-Carugo K, Lenarčič B. Crystal structure and its bearing towards an understanding of key biological functions of EpCAM. Nat Commun 2014; 5:4764. [DOI: 10.1038/ncomms5764] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 07/21/2014] [Indexed: 12/19/2022] Open
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EpCAM is overexpressed in local and metastatic prostate cancer, suppressed by chemotherapy and modulated by MET-associated miRNA-200c/205. Br J Cancer 2014; 111:955-64. [PMID: 24992580 PMCID: PMC4150273 DOI: 10.1038/bjc.2014.366] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 06/07/2014] [Indexed: 12/14/2022] Open
Abstract
Background: Expression of epithelial cell adhesion molecule (EpCAM) is deregulated in epithelial malignancies. Beside its role in cell adhesion, EpCAM acts as signalling molecule with tumour-promoting functions. Thus, EpCAM is part of the molecular network of oncogenic receptors and considered an interesting therapeutic target. Methods: Here, we thoroughly characterised EpCAM expression on mRNA and protein level in comprehensive tissue studies including non-cancerous prostate specimens, primary tumours of different grades and stages, metastatic lesions, and therapy-treated tumour specimens, as well as in prostate cancer cell lines. Results: Epithelial cell adhesion molecule was overexpressed at mRNA and at protein level in prostate cancer tissues and cell lines. Altered EpCAM expression was an early event in prostate carcinogenesis with an upregulation in low-grade cancers and further induction in high-grade tumours and metastatic lesions. Interestingly, EpCAM was repressed upon induction of epithelial-to-mesenchymal transition (EMT) following chemotherapeutic treatment with docetaxel. Oppositely, re-induction of the epithelial phenotype through miRNAs miR-200c and miR-205, two inducers of mesenchymal-to-epithelial transition (MET), led to re-induction of EpCAM in chemoresistant cells. Furthermore, we prove that EpCAM cleavage, the first step of EpCAM signalling takes place in prostate cancer cells but in contrast to other cancer entities, EpCAM has no measurable impact on the proliferative behaviour of prostate cells, in vitro. Conclusions: In conclusion, our data confirm that EpCAM overexpression is an early event during prostate cancer progression. Epithelial cell adhesion molecule displays a dynamic, heterogeneous expression and associates with epithelial cells rather than mesenchymal, chemoresistant cells along with processes of EMT and MET.
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