title: Overexpression of CD9 in human breast cancer cells promotes the development of bone metastases.
abstract: BACKGROUND
  Bone is a preferred target for circulating metastatic breast cancer cells. We found that the CD9 protein was up-regulated in the B02 osteotropic cell line, derived from the aggressive parental MDA-MB-231 breast cancer cell line. Here, we investigated the putative relationship between CD9 expression and the osteotropic phenotype.
  
  
  METHODS
  Overexpression of CD9 was analyzed by immunoblotting in different cell lines. Immunohistochemistry was used to assess CD9 expression in primary tumors and metastatic lesions. In vivo experiments were conducted in mice using a monoclonal antibody against CD9.
  
  
  RESULTS
  CD9 overexpression was confirmed in osteotropic cells. CD9 was significantly overexpressed in bone metastases versus primary tumors and visceral metastatic lesions. Finally, in vivo experiments showed that an antibody against CD9 delays homing of B02 cells in bone marrow, slowing down bone destruction.
  
  
  CONCLUSIONS
  Our study reveals a potential implication of CD9 in the formation of bony metastases from breast cancer cells.
authors.affiliation: Laboratoire de Physiologie Cellulaire et Moléculaire, Université d'Amiens, UFR des Sciences, 33 Rue Saint-Leu, 80039 Amiens Cedex 1, France. Philippe.Kischel@u-picardie.fr
authors.forename: Philippe
authors.initials: P
authors.lastname: Kischel
authors.forename: Akeila
authors.initials: A
authors.lastname: Bellahcene
authors.forename: Blandine
authors.initials: B
authors.lastname: Deux
authors.forename: Virginie
authors.initials: V
authors.lastname: Lamour
authors.forename: Rowan
authors.initials: R
authors.lastname: Dobson
authors.forename: Edwin
authors.initials: E
authors.lastname: DE Pauw
authors.forename: Philippe
authors.initials: P
authors.lastname: Clezardin
authors.forename: Vincent
authors.initials: V
authors.lastname: Castronovo
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D014408:Biomarkers, Tumor / Q000096:biosynthesis*; D001859:Bone Neoplasms / Q000378:metabolism / Q000556:secondary*; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D005260:Female; D006801:Humans; D015151:Immunoblotting; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008875:Middle Aged; D060245:Tetraspanin 29 / Q000096:biosynthesis*; D015854:Up-Regulation
chemical_list: D014408:Biomarkers, Tumor; C554869:CD9 protein, human; D060245:Tetraspanin 29