title: Neoplastic transformation of porcine mammary epithelial cells in vitro and tumor formation in vivo.
abstract: BACKGROUND
  The mammary glands of pigs share many functional and morphological similarities with the breasts of humans, raising the potential of their utility for research into the mechanisms underlying normal mammary function and breast carcinogenesis. Here we sought to establish a model for the efficient manipulation and transformation of porcine mammary epithelial cells (pMEC) in vitro and tumor growth in vivo.
  
  
  METHODS
  We utilized a vector encoding the red florescent protein tdTomato to transduce populations of pMEC from Yorkshire -Hampshire crossbred female pigs in vitro and in vivo. Populations of primary pMEC were then separated by FACS using markers to distinguish epithelial cells (CD140a-) from stromal cells (CD140a+), with or without further enrichment for basal and luminal progenitor cells (CD49f+). These separated pMEC populations were transduced by lentivirus encoding murine polyomavirus T antigens (Tag) and tdTomato and engrafted to orthotopic or ectopic sites in immunodeficient NOD.Cg-Prkdc (scid) Il2rg (tm1Wjl) /SzJ (NSG) mice.
  
  
  RESULTS
  We demonstrated that lentivirus effectively transduces pMEC in vitro and in vivo. We further established that lentivirus can be used for oncogenic-transformation of pMEC ex vivo for generating mammary tumors in vivo. Oncogenic transformation was confirmed in vitro by anchorage-independent growth, increased cell proliferation, and expression of CDKN2A, cyclin A2 and p53 alongside decreased phosphorylation of Rb. Moreover, Tag-transformed CD140a- and CD140a-CD49f + pMECs developed site-specific tumors of differing histopathologies in vivo.
  
  
  CONCLUSIONS
  Herein we establish a model for the transduction and oncogenic transformation of pMEC. This is the first report describing a porcine model of mammary epithelial cell tumorigenesis that can be applied to the study of human breast cancers.
authors.affiliation: Department of Animal Science, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA. arrowson@ucdavis.edu.|Present Address: Department of Biochemistry and Molecular Medicine, University of California Davis School of Medicine, Sacramento, CA, USA. arrowson@ucdavis.edu.
authors.forename: A R
authors.initials: AR
authors.lastname: Rowson-Hodel
authors.affiliation: Department of Animal Science, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA. rodrigo.manjarin@bmc.edu.|Present Address: USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX, USA. rodrigo.manjarin@bmc.edu.
authors.forename: R
authors.initials: R
authors.lastname: Manjarin
authors.affiliation: Department of Animal Science, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA. jftrott@ucdavis.edu.
authors.forename: J F
authors.initials: JF
authors.lastname: Trott
authors.affiliation: Center for Comparative Medicine, University of California Davis, One Shields Avenue, Davis, CA, USA. rdcardiff@ucdavis.edu.
authors.forename: R D
authors.initials: RD
authors.lastname: Cardiff
authors.affiliation: Center for Comparative Medicine, University of California Davis, One Shields Avenue, Davis, CA, USA. adborowsky@ucdavis.edu.
authors.forename: A D
authors.initials: AD
authors.lastname: Borowsky
authors.affiliation: Department of Animal Science, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA. rchovey@ucdavis.edu.
authors.forename: R C
authors.initials: RC
authors.lastname: Hovey
mesh_terms: D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000235:genetics*; D049109:Cell Proliferation; D002472:Cell Transformation, Viral / Q000235:genetics*; D002478:Cells, Cultured; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D005822:Genetic Vectors; D066298:In Vitro Techniques; D016086:Lentivirus / Q000235:genetics* / Q000502:physiology; D008321:Mammary Glands, Animal / Q000473:pathology / Q000637:transplantation* / Q000821:virology; D008325:Mammary Neoplasms, Experimental / Q000209:etiology / Q000473:pathology*; D011120:Polyomavirus / Q000235:genetics / Q000276:immunology*; D013552:Swine
chemical_list: D000952:Antigens, Polyomavirus Transforming