Human prolactin receptors are insensitive to mouse prolactin: implications for xenotransplant modeling of human breast cancer in mice

• Published in: Journal of endocrinology Vol. 188; no. 3; pp. 589 - 601
• Main Authors: Utama, F E, LeBaron, M J, Neilson, L M, Sultan, A S, Parlow, A F, Wagner, K-U, Rui, H
• Format: Journal Article
• Language: English
• Published: Colchester BioScientifica 01.03.2006; Portland Press
• Subjects: Analysis of Variance; Animals; Biological and medical sciences; Breast Neoplasms - metabolism; Breast Neoplasms - pathology; Cell Line, Tumor; Cell Proliferation; Electroporation; Female; Fundamental and applied biological sciences. Psychology; Humans; Immunoblotting - methods; Immunoprecipitation - methods; Mice; Mice, Nude; Models, Animal; Mother. Fetoplacental unit. Mammary gland. Milk; Neoplasm Transplantation; Pregnancy. Parturition. Lactation; Prolactin - metabolism; Prolactin - pharmacology; Protein Binding; Receptors, Prolactin - genetics; Receptors, Prolactin - metabolism; Regular papers; Reverse Transcriptase Polymerase Chain Reaction; Species Specificity; STAT5 Transcription Factor - metabolism; Transplantation, Heterologous; Vertebrates: reproduction; Human; Rodentia; Heterograft; In vitro; Breast carcinoma; Vertebrata; Mammalia; Cell line; Adenohypophyseal hormone; Mouse; Prolactin; Interspecific recognition; Biological receptor
• ISSN: 0022-0795; 1479-6805
• DOI: 10.1677/joe.1.06560

Experimental testing of growth, metastatic progression and drug responsiveness of human breast cancer in vivo is performed in immunodeficient mice. Drug candidates need to show promise against human breast cancer in mice before being allowed into clinical trials. Breast cancer growth is under endocrine control by ovarian steroids and the pituitary peptide hormone prolactin. While it is recognized that the most relevant biologic effects of prolactin are achieved with prolactin from the matching species, the biologic efficacy of mouse prolactin for human prolactin receptors has not been recorded. Thus, it is unclear whether the mouse endocrine environment adequately reflects the hormonal environment in breast cancer patients with regard to prolactin. We now show both recombinant and natural pituitary-derived mouse prolactin to be a poor agonist for human prolactin receptors. Mouse prolactin failed to induce human prolactin receptor-mediated biologic responses of cell clustering, proliferation, gene induction and signal transduction, including activation of Stat5, Stat3, Erk1/2 and Akt pathways. Consistent data were derived from human breast cancer lines T-47D, MCF-7 and ZR-75.1, as well as human prolactin receptor-transfected COS-7 and 32D cells. Failure of mouse prolactin to activate human prolactin receptors uncovers a key deficiency of the mouse endocrine environment for human xenotransplant studies. Since most human breast cancers express prolactin receptors, human breast cancer transferred into mice is unnaturally selected for growth in the absence of circulating prolactin. The new insight raises concerns about the validity of analyzing biology and drug responsiveness of human breast cancer in existing mouse xenotransplant models.