title: Reevaluation of the proposed autocrine proliferative function of prolactin in breast cancer.
abstract: The pituitary hormone prolactin (PRL) has been implicated in tumourigenesis. Expression of PRL and its receptor (PRLR) was reported in human breast epithelium and breast cancer cells. It was suggested that PRL may act as an autocrine/paracrine growth factor. Here, we addressed the role of locally synthesised PRL in breast cancer. We analysed the expression of PRL in human breast cancer tumours using qPCR analysis and in situ hybridization (ISH). PRL mRNA expression was very low or undetectable in the majority of samples in three cDNA arrays representing samples from 144 breast cancer patients and in 13 of 14 breast cancer cell lines when analysed by qPCR. In accordance, PRL expression did not reach detectable levels in any of the 19 human breast carcinomas or 5 cell lines, which were analysed using a validated ISH protocol. Two T47D-derived breast cancer cell lines were stably transfected with PRL-expressing constructs. Conditioned medium from the T47D/PRL clones promoted proliferation of lactogen-dependent Nb2 cells and control T47D cells. Surprisingly, the PRL-producing clones themselves displayed a lower proliferation rate as compared to the control cells. Their PRLR protein level was reduced and the cells were no longer responsive to exogenous recombinant PRL. Taken together, these data strongly indicate that autocrine PRL signalling is unlikely to be a general mechanism promoting tumour growth in breast cancer patients.
authors.affiliation: Biopharmaceutical Research Unit, Novo Nordisk A/S, Bagsvaerd, Denmark.
authors.forename: Louise Maymann
authors.initials: LM
authors.lastname: Nitze
authors.forename: Elisabeth Douglas
authors.initials: ED
authors.lastname: Galsgaard
authors.forename: Nanni
authors.initials: N
authors.lastname: Din
authors.forename: Vibe Luja
authors.initials: VL
authors.lastname: Lund
authors.forename: Birgitte Bruun
authors.initials: BB
authors.lastname: Rasmussen
authors.forename: Martin Werner
authors.initials: MW
authors.lastname: Berchtold
authors.forename: Leif
authors.initials: L
authors.lastname: Christensen
authors.forename: Svetlana
authors.initials: S
authors.lastname: Panina
mesh_terms: D019898:Autocrine Communication; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002277:Carcinoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D005260:Female; D015870:Gene Expression; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D011388:Prolactin / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D011981:Receptors, Prolactin / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D012333:RNA, Messenger; D011981:Receptors, Prolactin; D011388:Prolactin