Re-evaluation of the prolactin receptor expression in human breast cancer.
The pituitary hormone PRL is involved in tumorigenesis in rodents and humans. PRL promotes proliferation, survival and migration of cancer cells acting via the PRL receptor (PRLR). Aiming to perform a large-scale immunohistochemical (IHC) screening of human mammary carcinomas for PRLR expression, we evaluated the specificity of commercially available anti-human PRLR antibodies (B6.2, U5, PRLRi pAb, 1A2B1, 250448 and H-300). The latter three antibodies were found to specifically recognise PRLR. The relative PRLR expression level detected with these antibodies closely reflected the level of (125)I-PRL binding to the cell surface. The monoclonal antibody (mAb) 250448 was specific for the N-()glycosylated form of PRLR and blocked PRL binding and signalling. The PRLRi polyclonal antibody recognised cytokeratin-18. The mAb B6.2, previously used in a number of studies, was found to lack specificity for PRLR and to rather recognise a PRLR-associated protein. The mAb U5 raised against the rat PRLR did not cross-react with the human receptor. Only one mAb, 1A2B1, was found useful for detection of PRLR in IHC applications. This antibody recognised PRLR expressed in human breast cancer cell lines and decidual cells in tissue sections of human placenta. Screening of 160 mammary adenocarcinomas demonstrated significant immunoreactivity in only four tumours, indicating that PRLR is generally not strongly upregulated in human breast cancer. However, even a very low level of PRLR expression was found to be sufficient to mediate PRL responsiveness in breast cancer cell lines.
Galsgaard
Elisabeth Douglas
ED
Biopharmaceutical Research Unit, Novo Nordisk A/S, Novo Nordisk Park, Maaloev, Denmark.
Rasmussen
Birgitte Bruun
BB
Folkesson
Charlotta Grånäs
CG
Rasmussen
Louise Maymann
LM
Berchtold
Martin Werner
MW
Christensen
Leif
L
Panina
Svetlana
S
D000818:Animals; D000918:Antibody Specificity; D001943:Breast Neoplasms / Q000235:genetics*; D016466:CHO Cells; D002277:Carcinoma / Q000235:genetics*; D006224:Cricetinae; D003412:Cricetulus; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D019073:HT29 Cells; D006801:Humans; D011388:Prolactin / Q000378:metabolism; D011485:Protein Binding; D011981:Receptors, Prolactin / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D046888:Tissue Array Analysis; D014407:Tumor Cells, Cultured
D011981:Receptors, Prolactin; D011388:Prolactin