title: The carcinoma-associated antigen EpCAM upregulates c-myc and induces cell proliferation.
abstract: Epithelial cell adhesion molecule (EpCAM) is a membrane glycoprotein expressed on adenomatous and simple epithelia, where it is involved in homophilic adhesion at the basolateral membrane. Carcinomas strongly overexpress EpCAM through an, as yet, unknown mechanism. Interestingly, otherwise EpCAM-negative squamous epithelia are seen to express EpCAM concomitant with their transformation and de-differentiation. The amount of EpCAM and the number of expressing cells both increase with the grade of dysplasia. Despite an important amount of data correlating the expression of EpCAM with cellular proliferation and de-differentiation, such as the coexpression with Ki-67, a marker for proliferation, it is unknown whether EpCAM may directly contribute to carcinogenesis. Here, we show that EpCAM has a direct impact on cell cycle and proliferation, and the ability to rapidly upregulate the proto-oncogene c-myc and cyclin A/E. Human epithelial 293 cells as well as murine NIH3T3 fibroblasts expressing EpCAM had a decreased requirement for growth factors, enhanced metabolic activity and colony formation capacity. Importantly, the inhibition of EpCAM expression with antisense mRNA led to a strong decrease in proliferation and metabolism in human carcinoma cells. Moreover, domain swapping experiments demonstrated that the intracellular part of EpCAM is necessary and sufficient to transduce the effects described. Thus, the data presented here highlight the role of EpCAM, demonstrating for the first time a direct link to cell cycle and proliferation.
authors.affiliation: Clinical Cooperation Group Molecular Oncology, GSF National Research Center for Environment and Health, and Department of Otorhinolaryngology, Ludwig-Maximilians-University, Marchioninistr. 15, Munich D-81377, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Münz
authors.forename: Cuong
authors.initials: C
authors.lastname: Kieu
authors.forename: Brigitte
authors.initials: B
authors.lastname: Mack
authors.forename: Bärbel
authors.initials: B
authors.lastname: Schmitt
authors.forename: Reinhard
authors.initials: R
authors.lastname: Zeidler
authors.forename: Olivier
authors.initials: O
authors.lastname: Gires
mesh_terms: D016475:3T3 Cells / Q000378:metabolism / Q000473:pathology; D000818:Animals; D000951:Antigens, Neoplasm / Q000235:genetics / Q000378:metabolism*; D015197:Carcinogenicity Tests; D002277:Carcinoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D002478:Cells, Cultured; D019925:Cyclin A / Q000235:genetics / Q000378:metabolism; D019927:Cyclin E / Q000235:genetics / Q000378:metabolism; D000071858:Epithelial Cell Adhesion Molecule; D004847:Epithelial Cells / Q000378:metabolism / Q000473:pathology; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D017434:Protein Structure, Tertiary; D000090063:Proto-Oncogene Mas; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics* / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D000951:Antigens, Neoplasm; D015815:Cell Adhesion Molecules; D019925:Cyclin A; D019927:Cyclin E; D000071858:Epithelial Cell Adhesion Molecule; C000715470:MAS1 protein, human; C489427:MYC protein, human; C489428:Myc protein, mouse; D000090063:Proto-Oncogene Mas; D016271:Proto-Oncogene Proteins c-myc