title: Loss of N-Cadherin Expression in Tumor Transplants Produced From As+3- and Cd+2-Transformed Human Urothelial (UROtsa) Cell Lines.
abstract: BACKGROUND
  Epithelial to mesenchymal transition is a process in which a cell experiences a loss of epithelial cell characteristics and acquires a more mesenchymal cell phenotype. In cancer, epithelial to mesenchymal transition has been proposed to play an important role during specific stages of tumor progression. The role epithelial to mesenchymal transition and mesenchymal to epithelial transition might play in toxicant-induced urothelial cancer is unknown.
  
  
  METHODS
  Real-time PCR, Western blotting, immuno-histochemistry and immuno-fluorescence were used to determine the expression of E- and N-cadherin in the UROtsa parent, the As+3- and Cd+2-transformed cell lines, the spheroids isolated from these cell lines as well as the tumor heterotransplants that were produced by the injection of the transformed cells into immune compromised mice.
  
  
  RESULTS
  This study showed that N-cadherin expression was increased in 6 As+3- and 7 Cd+2- transformed cell lines generated from human urothelial cells (UROtsa). The expression varied within each cell line, with 10% to 95% of the cells expressing N-cadherin. Tumors produced from these cell lines showed no expression of the N-cadherin protein. Spheroids which are made up of putative cancer initiating cells produced from these cell lines showed only background expression of N-cadherin mRNA, increased expression of aldehyde dehydrogenase 1 mRNA and produced tumors which did not express N-cadherin. There was no change in the expression of E-cadherin in the tumors, and the tumors formed by all the As+3 and Cd+2-transformed cell lines and cancer initiating cells stained intensely and uniformly for E-cadherin.
  
  
  CONCLUSIONS
  The finding that the cells expressing N-cadherin gave rise to tumors with no expression of N-cadherin is in agreement with the classical view of epithelial to mesenchymal transition. Epithelial to mesenchymal transition and N-cadherin are associated with dissemination and not with the ability to establish new tumor growth. Mesenchymal to epithelial transition and E-cadherin are viewed as necessary for a cell to establish a new metastatic site. The lack of N-cadherin expression in tumor transplants is consistent with E-cadherin expressing cells "seeding" a site for tumor growth. The study shows that a minority population of cultured cells can be the initiators of tumor growth.
authors.affiliation: Department of Pathology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota, United States of America.
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Sandquist
authors.affiliation: Department of Pathology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota, United States of America.
authors.forename: Seema
authors.initials: S
authors.lastname: Somji
authors.affiliation: Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota, United States of America.
authors.forename: Jane R
authors.initials: JR
authors.lastname: Dunlevy
authors.affiliation: Department of Pathology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota, United States of America.
authors.forename: Scott H
authors.initials: SH
authors.lastname: Garrett
authors.affiliation: Department of Pathology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota, United States of America.
authors.forename: Xu Dong
authors.initials: XD
authors.lastname: Zhou
authors.affiliation: Department of Pathology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota, United States of America.
authors.forename: Andrea
authors.initials: A
authors.lastname: Slusser-Nore
authors.affiliation: Department of Pathology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota, United States of America.
authors.forename: Donald A
authors.identifier: http://orcid.org/0000-0002-7163-5236
authors.initials: DA
authors.lastname: Sens
mesh_terms: D000080924:Aldehyde Dehydrogenase 1 Family; D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism*; D018053:Arsenites / Q000633:toxicity*; D015820:Cadherins / Q000235:genetics / Q000378:metabolism*; D002104:Cadmium / Q000633:toxicity*; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000139:chemically induced* / Q000235:genetics / Q000378:metabolism; D058750:Epithelial-Mesenchymal Transition; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007527:Isoenzymes / Q000235:genetics; D051379:Mice; D009368:Neoplasm Transplantation; D050697:Retinal Dehydrogenase / Q000235:genetics; D018874:Spheroids, Cellular / Q000378:metabolism; D001749:Urinary Bladder Neoplasms / Q000235:genetics / Q000378:metabolism*; D019459:Urothelium / Q000378:metabolism / Q000473:pathology*
chemical_list: D015703:Antigens, CD; D018053:Arsenites; C050361:CDH2 protein, human; D015820:Cadherins; D007527:Isoenzymes; D002104:Cadmium; D000080924:Aldehyde Dehydrogenase 1 Family; C510223:ALDH1A1 protein, human; C515028:ALDH1A1 protein, mouse; D050697:Retinal Dehydrogenase