title: Expression of osteoprotegerin (OPG), TNF related apoptosis inducing ligand (TRAIL), and receptor activator of nuclear factor kappaB ligand (RANKL) in human breast tumours.
abstract: BACKGROUND
  Osteoprotegerin (OPG) is involved in the regulation of bone turnover through binding to the receptor activator of nuclear factor kappaB ligand (RANKL), and has also been reported to be a potential survival factor for several different cell types. The survival effects are mediated through inhibition of the activity of tumour necrosis factor related apoptosis inducing ligand (TRAIL). Both breast and prostate cancer cells produce sufficient amounts of OPG to be protected against the effects of TRAIL in vitro.
  
  
  OBJECTIVE
  To investigate the spatial expression of OPG, RANKL, and TRAIL in non-neoplastic breast tissue and breast cancer, and its relation with oestrogen receptor (ER) expression.
  
  
  METHODS
  Forty breast cancers (20 ER+, 20 ER-) and five non-neoplastic breast tissue samples were stained with antibodies against OPG, RANKL, and TRAIL.
  
  
  RESULTS
  OPG was not expressed in non-neoplastic breast tissue except when colocalised with altered columnar epithelium. RANKL was expressed at the apical surface of luminal epithelial cells and TRAIL was expressed in myoepithelial cells. All three proteins were expressed in some breast cancers but showed no significant association with tumour type. OPG expression showed a significant positive correlation with ER expression (p = 0.011).
  
  
  CONCLUSIONS
  This is the first published study of the spatial expression of OPG, RANKL, and TRAIL in breast tissue and breast cancer. The localisation of each protein was specific and they were not colocalised. This specificity may provide a useful marker of functional differentiation in breast cancer; for example, TRAIL expression as a marker of myoepithelial differentiation.
authors.affiliation: Academic Units of Clinical Oncology, Division of Genomic Medicine, School of Medicine and Biomedical Sciences, University of Sheffield, Sheffield S10 2RX, UK.
authors.forename: C
authors.initials: C
authors.lastname: Van Poznak
authors.forename: S S
authors.initials: SS
authors.lastname: Cross
authors.forename: M
authors.initials: M
authors.lastname: Saggese
authors.forename: C
authors.initials: C
authors.lastname: Hudis
authors.forename: K S
authors.initials: KS
authors.lastname: Panageas
authors.forename: L
authors.initials: L
authors.lastname: Norton
authors.forename: R E
authors.initials: RE
authors.lastname: Coleman
authors.forename: I
authors.initials: I
authors.lastname: Holen
mesh_terms: D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D014408:Biomarkers, Tumor / Q000378:metabolism*; D001940:Breast / Q000378:metabolism; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000378:metabolism / Q000473:pathology; D018275:Carcinoma, Lobular / Q000378:metabolism / Q000473:pathology; D002352:Carrier Proteins / Q000378:metabolism; D005260:Female; D006023:Glycoproteins / Q000378:metabolism*; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism*; D009361:Neoplasm Invasiveness; D009363:Neoplasm Proteins / Q000378:metabolism; D053244:Osteoprotegerin; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism*; D012189:Retrospective Studies; D053221:TNF-Related Apoptosis-Inducing Ligand; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
chemical_list: D051017:Apoptosis Regulatory Proteins; D014408:Biomarkers, Tumor; D002352:Carrier Proteins; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; D053244:Osteoprotegerin; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D018124:Receptors, Tumor Necrosis Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C505686:TNFRSF11A protein, human; C506030:TNFRSF11B protein, human; C505653:TNFSF10 protein, human; C505688:TNFSF11 protein, human; D014409:Tumor Necrosis Factor-alpha