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Bennesch MA, Picard D. Minireview: Tipping the balance: ligand-independent activation of steroid receptors. Mol Endocrinol 2015; 29:349-63. [PMID: 25625619 DOI: 10.1210/me.2014-1315] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Steroid receptors are prototypical ligand-dependent transcription factors and a textbook example for allosteric regulation. According to this canonical model, binding of cognate steroid is an absolute requirement for transcriptional activation. Remarkably, the simple one ligand-one receptor model could not be farther from the truth. Steroid receptors, notably the sex steroid receptors, can receive multiple inputs. Activation of steroid receptors by other signals, working through their own signaling pathways, in the absence of the cognate steroids, represents the most extreme form of signaling cross talk. Compared with cognate steroids, ligand-independent activation pathways produce similar but not identical outputs. Here we review the phenomena and discuss what is known about the underlying molecular mechanisms and the biological significance. We hypothesize that steroid receptors may have evolved to be trigger happy. In addition to their cognate steroids, many posttranslational modifications and interactors, modulated by other signals, may be able to tip the balance.
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Affiliation(s)
- Marcela A Bennesch
- Département de Biologie Cellulaire, Université de Genève, Sciences III, CH-1211 Genève 4, Switzerland
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2
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O'Leary KA, Shea MP, Schuler LA. Modeling prolactin actions in breast cancer in vivo: insights from the NRL-PRL mouse. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 846:201-20. [PMID: 25472540 DOI: 10.1007/978-3-319-12114-7_9] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Elevated exposure to prolactin (PRL) is epidemiologically associated with an increased risk of aggressive ER+ breast cancer. To understand the underlying mechanisms and crosstalk with other oncogenic factors, we developed the NRL-PRL mouse. In this model, mammary expression of a rat prolactin transgene raises local exposure to PRL without altering estrous cycling. Nulliparous females develop metastatic, histotypically diverse mammary carcinomas independent from ovarian steroids, and most are ER+. These characteristics resemble the human clinical disease, facilitating study of tumorigenesis, and identification of novel preventive and therapeutic approaches.
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Affiliation(s)
- Kathleen A O'Leary
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, USA,
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3
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Sangeeta Devi Y, Halperin J. Reproductive actions of prolactin mediated through short and long receptor isoforms. Mol Cell Endocrinol 2014; 382:400-410. [PMID: 24060636 DOI: 10.1016/j.mce.2013.09.016] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Revised: 07/20/2013] [Accepted: 09/13/2013] [Indexed: 10/26/2022]
Abstract
Prolactin (PRL) is a polypeptide hormone with a wide range of physiological functions, and is critical for female reproduction. PRL exerts its action by binding to membrane bound receptor isoforms broadly classified as the long form and the short form receptors. Both receptor isoforms are highly expressed in the ovary as well as in the uterus. Although signaling through the long form is believed to be more predominant, it remains unclear whether activation of this isoform alone is sufficient to support reproductive functions or whether both types of receptor are required. The generation of transgenic mice selectively expressing either the short or the long form of PRL receptor has provided insight into the differential signaling mechanisms and physiological functions of these receptors. This review describes the essential finding that both long and short receptor isoforms are crucial for ovarian functions and female fertility, and highlights novel mechanisms of action for these receptors.
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Affiliation(s)
- Y Sangeeta Devi
- Department of Obstetrics, Gynecology and Reproductive Biology, College of Human Medicine, Michigan State University, Grand Rapids, MI-49503, USA.
| | - Julia Halperin
- Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y Diagnóstico (CEBBAD), Universidad Maimónides, Hidalgo 775 6to piso, C1405BCK Ciudad Autónoma de Buenos Aires, Argentina and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Rivadavia 1917, Ciudad Autónoma de Buenos Aires, Argentina.
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4
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Christensen HR, Murawsky MK, Horseman ND, Willson TA, Gregerson KA. Completely humanizing prolactin rescues infertility in prolactin knockout mice and leads to human prolactin expression in extrapituitary mouse tissues. Endocrinology 2013; 154:4777-89. [PMID: 24029242 PMCID: PMC3836079 DOI: 10.1210/en.2013-1476] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A variety of fundamental differences have evolved in the physiology of the human and rodent prolactin (PRL) systems. The PRL gene in humans and other primates contains an alternative promoter, 5.8 kbp upstream of the pituitary transcription start site, which drives expression of PRL in "extrapituitary" tissues, where PRL is believed to exert local, or paracrine, actions. Several of these extrapituitary PRL tissues serve a reproductive function (eg, mammary gland, decidua, prostate, etc), consistent with the hypothesis that local PRL production may be involved in, and required for, normal reproductive physiology in primates. Rodent research models have generated significant findings regarding the role of PRL in reproduction. Specifically, disruption (knockout) of either the PRL gene or its receptor causes profound female reproductive defects at several levels (ovaries, preimplantation endometrium, mammary glands). However, the rodent PRL gene differs significantly from the human, most notably lacking the alternative promoter. Understanding of the physiological regulation and function of extrapituitary PRL has been limited by the absence of a readily accessible experimental model, because the rodent PRL gene does not contain the alternative promoter. To overcome these limitations, we have generated mice that have been "humanized" with regard to the structural gene and tissue expression of PRL. Here, we present the characterization of these animals, demonstrating that the human PRL transgene is responsive to known physiological regulators both in vitro and in vivo. More importantly, the expression of the human PRL transgene is able to rescue the reproductive defects observed in mouse PRL knockout (mPRL(-)) females, validating their usefulness in studying the function or regulation of this hormone in a manner that is relevant to human physiology.
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Reuwer AQ, Nowak-Sliwinska P, Mans LA, van der Loos CM, von der Thüsen JH, Twickler MTB, Spek CA, Goffin V, Griffioen AW, Borensztajn KS. Functional consequences of prolactin signalling in endothelial cells: a potential link with angiogenesis in pathophysiology? J Cell Mol Med 2013; 16:2035-48. [PMID: 22128761 PMCID: PMC3822974 DOI: 10.1111/j.1582-4934.2011.01499.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Prolactin is best known as the polypeptide anterior pituitary hormone, which regulates the development of the mammary gland. However, it became clear over the last decade that prolactin contributes to a broad range of pathologies, including breast cancer. Prolactin is also involved in angiogenesis via the release of pro-angiogenic factors by leukocytes and epithelial cells. However, whether prolactin also influences endothelial cells, and whether there are functional consequences of prolactin-induced signalling in the perspective of angiogenesis, remains so far elusive. In the present study, we show that prolactin induces phosphorylation of ERK1/2 and STAT5 and induces tube formation of endothelial cells on Matrigel. These effects are blocked by a specific prolactin receptor antagonist, del1-9-G129R-hPRL. Moreover, in an in vivo model of the chorioallantoic membrane of the chicken embryo, prolactin enhances vessel density and the tortuosity of the vasculature and pillar formation, which are hallmarks of intussusceptive angiogenesis. Interestingly, while prolactin has only little effect on endothelial cell proliferation, it markedly stimulates endothelial cell migration. Again, migration was reverted by del1-9-G129R-hPRL, indicating a direct effect of prolactin on its receptor. Immunohistochemistry and spectral imaging revealed that the prolactin receptor is present in the microvasculature of human breast carcinoma tissue. Altogether, these results suggest that prolactin may directly stimulate angiogenesis, which could be one of the mechanisms by which prolactin contributes to breast cancer progression, thereby providing a potential tool for intervention.
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Affiliation(s)
- Anne Q Reuwer
- Department of Vascular Medicine, Academic Medical Center, Amsterdam, The Netherlands.
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6
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Chen CC, Stairs DB, Boxer RB, Belka GK, Horseman ND, Alvarez JV, Chodosh LA. Autocrine prolactin induced by the Pten-Akt pathway is required for lactation initiation and provides a direct link between the Akt and Stat5 pathways. Genes Dev 2012; 26:2154-68. [PMID: 23028142 DOI: 10.1101/gad.197343.112] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Extrapituitary prolactin (Prl) is produced in humans and rodents; however, little is known about its in vivo regulation or physiological function. We now report that autocrine prolactin is required for terminal mammary epithelial differentiation during pregnancy and that its production is regulated by the Pten-PI3K-Akt pathway. Conditional activation of the PI3K-Akt pathway in the mammary glands of virgin mice by either Akt1 expression or Pten deletion rapidly induced terminal mammary epithelial differentiation accompanied by the synthesis of milk despite the absence of lobuloalveolar development. Surprisingly, we found that mammary differentiation was due to the PI3K-Akt-dependent synthesis and secretion of autocrine prolactin and downstream activation of the prolactin receptor (Prlr)-Jak-Stat5 pathway. Consistent with this, Akt-induced mammary differentiation was abrogated in Prl(-/-), Prlr(-/-), and Stat5(-/-) mice. Furthermore, cells treated with conditioned medium from mammary glands in which Akt had been activated underwent rapid Stat5 phosphorylation in a manner that was blocked by inhibition of Jak2, treatment with an anti-Prl antibody, or deletion of the prolactin gene. Demonstrating a physiological requirement for autocrine prolactin, mammary glands from lactation-defective Akt1(-/-);Akt2(+/-) mice failed to express autocrine prolactin or activate Stat5 during late pregnancy despite normal levels of circulating serum prolactin and pituitary prolactin production. Our findings reveal that PI3K-Akt pathway activation is necessary and sufficient to induce autocrine prolactin production in the mammary gland, Stat5 activation, and terminal mammary epithelial differentiation, even in the absence of the normal developmental program that prepares the mammary gland for lactation. Together, these findings identify a function for autocrine prolactin during normal development and demonstrate its endogenous regulation by the PI3K-Akt pathway.
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Affiliation(s)
- Chien-Chung Chen
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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7
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Michel E, Rohrer Bley C, Kowalewski MP, Feldmann SK, Reichler IM. Prolactin--to be reconsidered in canine mammary tumourigenesis? Vet Comp Oncol 2012; 12:93-105. [PMID: 22738741 DOI: 10.1111/j.1476-5829.2012.00337.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2012] [Revised: 05/18/2012] [Accepted: 06/01/2012] [Indexed: 12/19/2022]
Abstract
Mammary tumours represent the most common neoplastic disease of the female dog, and the incidence in female dogs is much higher than in women. Whereas the influence of sexual steroids on breast cancer (BC) development in dogs has been studied, very little is known about the role of prolactin (PRL). New studies show that until recently, the importance of PRL in human BC development and progression has been highly underestimated. PRL plays a role in promoting benign as well as malignant neoplastic cell growth in BC in vitro and in vivo. Sporadic publications proposed a tumour promotor role in the dog. The goal of this review is to summarize our knowledge about PRL and human BC as well as canine mammary tumourigenesis, and propose future research in this area.
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Affiliation(s)
- E Michel
- Section of Small Animal Reproduction, Clinic of Reproductive Medicine, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
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8
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Harvey S, Arámburo C, Sanders EJ. Extrapituitary production of anterior pituitary hormones: an overview. Endocrine 2012; 41:19-30. [PMID: 22169962 DOI: 10.1007/s12020-011-9557-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 11/14/2011] [Indexed: 10/15/2022]
Abstract
Protein hormones from the anterior pituitary gland have well-established endocrine roles in their peripheral target glands. It is, however, now known that these proteins are also produced within many of their target tissues, in which they act as local autocrine or paracrine factors, with physiological and/or pathophysiological significance. This emerging concept is the focus of this brief review.
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Affiliation(s)
- S Harvey
- Department of Physiology, University of Alberta, Edmonton, AB, T6G 2H7, Canada,
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9
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Clapp C, Thebault S, Jeziorski MC, Martínez De La Escalera G. Peptide hormone regulation of angiogenesis. Physiol Rev 2009; 89:1177-215. [PMID: 19789380 DOI: 10.1152/physrev.00024.2009] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
It is now apparent that regulation of blood vessel growth contributes to the classical actions of hormones on development, growth, and reproduction. Endothelial cells are ideally positioned to respond to hormones, which act in concert with locally produced chemical mediators to regulate their growth, motility, function, and survival. Hormones affect angiogenesis either directly through actions on endothelial cells or indirectly by regulating proangiogenic factors like vascular endothelial growth factor. Importantly, the local microenvironment of endothelial cells can determine the outcome of hormone action on angiogenesis. Members of the growth hormone/prolactin/placental lactogen, the renin-angiotensin, and the kallikrein-kinin systems that exert stimulatory effects on angiogenesis can acquire antiangiogenic properties after undergoing proteolytic cleavage. In view of the opposing effects of hormonal fragments and precursor molecules, the regulation of the proteases responsible for specific protein cleavage represents an efficient mechanism for balancing angiogenesis. This review presents an overview of the actions on angiogenesis of the above-mentioned peptide hormonal families and addresses how specific proteolysis alters the final outcome of these actions in the context of health and disease.
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Affiliation(s)
- Carmen Clapp
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Querétaro, Mexico.
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10
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Trott JF, Vonderhaar BK, Hovey RC. Historical perspectives of prolactin and growth hormone as mammogens, lactogens and galactagogues--agog for the future! J Mammary Gland Biol Neoplasia 2008; 13:3-11. [PMID: 18204889 DOI: 10.1007/s10911-008-9064-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2007] [Accepted: 01/02/2008] [Indexed: 10/22/2022] Open
Abstract
Around 80 years ago researchers first established that the pituitary gland regulates mammary gland function as demonstrated by the ability of its extracts to promote both mammogenesis and lactogenesis in animal models. Little did they realize that in fact two hormones, prolactin (PRL) and growth hormone (GH), were contributing to these effects. By the mid 1930s PRL had been purified as a distinct lactogen, while the galactopoietic effect of GH was confirmed after its purification in the 1940s. Interest in these hormones initially centered about their potential for increasing milk production, while in the latter half of the twentieth century it became obvious that these hormones also had the potential to influence mammary cancer development. During the past 50 years large strides have been made into understanding how these hormones signal to, and within, cells of the mammary gland, paralleling rapid developments in the fields of cellular and molecular biology. In compiling this review we have summarized the progress that has been made to date regarding roles for these hormones in the mammary gland, with a goal of ensuring that some of the seminal literature is not diluted or forgotten. In doing so it is clear that there are lessons to be learned from past experiences, where new methods and technologies will continue to present exciting new opportunities to revisit lingering questions regarding these fascinating hormones and this fascinating organ.
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Affiliation(s)
- Josephine F Trott
- Lactation and Mammary Gland Biology Group, Department of Animal Science, The University of Vermont, Burlington, VT 05401, USA
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11
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Ren X, Zhang X, Kim AS, Mikheev AM, Fang M, Sullivan RC, Bumgarner RE, Zarbl H. Comparative genomics of susceptibility to mammary carcinogenesis among inbred rat strains: role of reduced prolactin signaling in resistance of the Copenhagen strain. Carcinogenesis 2007; 29:177-85. [PMID: 17916903 DOI: 10.1093/carcin/bgm224] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
To elucidate the molecular basis for differential susceptibilities to mammary carcinogenesis, we compared the transcriptomes of normal mammary glands from pubescent female rats of the resistant Copenhagen (Cop) strain with those of the susceptible Fischer 344 (F344), August x Copenhagen Irish (ACI), Buffalo/N (Buf/N), Wistar-Furth (WF) strains and F1 (Cop x F344) progeny (F1). Gene expression profiles in mammary tissue within each rat strain were remarkably similar, indicating that gene expression was determined by genetic background. We next identified the subset of genes that were differentially expressed in all susceptible strains relative to the resistant Cop strain. Among these, the messenger RNAs encoding prolactin (Prl) and its cell surface receptor were significantly elevated in all susceptible strains. The expression levels of several Prl-regulated genes were also significantly elevated, indicating the presence of increased Prl signaling in mammary glands of all susceptible strains. Pathway analysis of gene expression profiles further identified the Prl-activated Jak/STAT-signaling pathway among the pathways that most distinguished sensitive rat strains from the resistant Cop rat. To test the hypothesis that reduced levels of the Prl signaling in mammary tissue partially contributed to the genetic resistance to mammary carcinogenesis, we used the neuroleptic drug, perphenazine, to transiently elevate serum Prl levels in the Cop strain. Whereas Cop rats are resistant to N-nitroso-N-methylurea (NMU)-induced mammary carcinogenesis, approximately 5% of pubescent Cop females treated with perphenazine and NMU exposure developed mammary adenocarcinomas with latencies comparable with those of sensitive strains. Together, these finding indicated that in the rat, the molecular mechanisms underlying genetic susceptibility to mammary carcinogenesis include de-regulation of Prl signaling.
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Affiliation(s)
- Xuefeng Ren
- Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
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12
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Affiliation(s)
- W Doppler
- Institut für Medizinische Chemie und Biochemie der Universität Innsbruck, Austria
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13
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Kindblom J, Dillner K, Sahlin L, Robertson F, Ormandy C, Törnell J, Wennbo H. Prostate hyperplasia in a transgenic mouse with prostate-specific expression of prolactin. Endocrinology 2003; 144:2269-78. [PMID: 12746285 DOI: 10.1210/en.2002-0187] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Prolactin (PRL) is one of several polypeptide factors known to exert trophic effects on the prostate. We have previously reported a dramatic prostate enlargement with concurrent chronic hyperprolactinemia and elevated serum androgen levels in a PRL transgenic mouse (Mt-PRL) with ubiquitous expression of the transgene. To address the role of local PRL action in the prostate, a new transgenic mouse model (Pb-PRL) was generated using the prostate-specific rat probasin (Pb) minimal promoter to drive expression of the rat PRL gene. Pb-PRL transgenic males developed a significant enlargement of both the dorsolateral and ventral prostate lobes evident from 10 wk of age and increasing with age. Expression of the transgene was restricted to the prostate and detected from 4 wk of age. Low levels of transgenic rat PRL were detectable in the serum of adult Pb-PRL animals. Serum androgen levels were normal. The Pb-PRL prostate displayed significant stromal hyperplasia, ductal dilation, and focal areas of epithelial dysplasia. Quantitative analysis of prostatic tissue cellularity demonstrated a marked increase in the stromal to epithelial ratio in all lobes of Mt-PRL and Pb-PRL transgenic prostates compared with controls. Microdissections demonstrated an increased ductal morphogenesis in dorsolateral and ventral prostate lobes of Mt-PRL prostate vs. Pb-PRL and controls. In conclusion, this study indicates the ability of PRL to promote, directly or indirectly, ductal morphogenesis in the developing prostate and further to induce abnormal growth primarily of the stroma in the adult gland in a setting of normal androgen levels.
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Affiliation(s)
- Jon Kindblom
- Department of Physiology, Göteborg University, Göteborg 405 30, Sweden.
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Abstract
The contribution of prolactin (PRL) to the pathogenesis and progression of human breast cancer at the cellular, transgenic, and epidemiological levels is increasingly appreciated. Acting at the endocrine and autocrine/paracrine levels, PRL functions to stimulate the growth and motility of human breast cancer cells. The actions of this ligand are mediated by at least six recognized PRL receptor isoforms found on, or secreted by, human breast epithelium. The PRL/PRL receptor complex associates with and activates several signaling networks that are shared with other members of the cytokine receptor superfamily. Coupled with the recently identified intranuclear function of PRL, these networks are integrated into the in vitro and in vivo actions induced by ligand. These findings indicate that antagonists of PRL/PRL receptor interaction or PRL receptor-associated signal transduction may be of considerable utility in the treatment of human breast cancer.
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Key Words
- cis, cytokine-inducible inhibitor of signaling
- cypb, cyclophilin b
- ecd, extracellular domain
- egf, epidermal growth factor
- ghr, gh receptor
- hprlr, human prlr
- icd, intracellular domain
- jak, janus kinase 2
- jnk, c-jun n-terminal kinase
- pias, peptide inhibitor of activated stat
- pi3k, phosphatidylinositol 3′-kinase
- prl, prolactin
- ptdins, phosphatidylinositol
- prlbp, prl binding protein
- prlr, prl receptor
- shp-2, sh2-containing protein tyrosine phosphatase
- socs, suppressor of cytokine signaling
- stat, signal transducer and activator of transcription
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Affiliation(s)
- Charles V Clevenger
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
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Koizumi M, Horiguchi K, Tomita Y, Kato Y, Harigaya T. Prolactin Gene Expression in the Mouse Nipple. J Reprod Dev 2003; 49:465-72. [PMID: 14967897 DOI: 10.1262/jrd.49.465] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In this study, we attempted to examine the presence of prolactin (PRL) messenger ribonucleic acid (mRNA) and protein in the mouse nipple and mammary gland in pregnancy and lactation. PRL-like substances were found by immunohistochemistry using an antibody against the mouse PRL (mPRL) in the sebaceous gland cells of the nipple during late pregnancy and lactation, and the cistern of alveoli in mammary glands during lactation. Western blot analysis of proteins extracted from the nipple and the mammary gland showed immunoreactive bands corresponding to molecular weights of approximate 16 kDa and 32 kDa, respectively. The expression of mRNA for mPRL in the nipple and mammary gland during late pregnancy and lactation was demonstrated by reverse transcription-polymerase chain reaction (RT-PCR), Southern blotting, and nucleotide sequence analyses. These results suggest that mPRL mRNA and its translation product are synthesized in the mouse nipple.
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Affiliation(s)
- Minoru Koizumi
- Laboratory of Functional Anatomy, Department of Life Sciences, Faculty of Agriculture, Meiji University, Kawasaki, Japan.
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Lantinga-van Leeuwen IS, Timmermans-Sprang EAP, Mol JA. Cloning and characterization of the 5'-flanking region of the canine growth hormone gene. Mol Cell Endocrinol 2002; 197:133-41. [PMID: 12431806 DOI: 10.1016/s0303-7207(02)00257-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The growth hormone (GH) gene is expressed in a variety of tissues outside the pituitary, including the mammary gland. GH expression in the mammary gland is stimulated by progestins. The local synthesis of mammary GH may provide a highly proliferative environment within the mammary gland that may contribute to the development or progression of mammary tumours. To elucidate the mechanism regulating mammary GH expression, we cloned the 5'-flanking region of the canine GH gene using inverse polymerase chain reaction. Gel-shift experiments showed that several sequences in the 5'-flanking region of the GH gene bind mammary nuclear proteins and may be involved in basal and progesterone-induced mammary GH expression. Sequence analysis and comparison with the GH promoters of human, rat, and mouse genes revealed a number of shared binding sites for transcription factors such as Pit-1, which is involved in pituitary GH expression, and for factors involved in the differentiation of lymphoid cells. Moreover, a putative binding site for the progesterone receptor (PR) was identified in all promoters, indicating that the progestin-induced expression of GH in mammary tissue is most probably a direct effect of activated PRs on the GH gene promoter and that this may occur in various species.
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Affiliation(s)
- Irma S Lantinga-van Leeuwen
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 8, 3584 CM Utrecht, The Netherlands
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HARIGAYA T, KOMORI M, WATANABE H, WATANABE S, MATSUI T. Prolactin gene expression in mouse pancreatic islets. Anim Sci J 2002. [DOI: 10.1046/j.1344-3941.2002.00010.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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18
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Park DS, Lee H, Riedel C, Hulit J, Scherer PE, Pestell RG, Lisanti MP. Prolactin negatively regulates caveolin-1 gene expression in the mammary gland during lactation, via a Ras-dependent mechanism. J Biol Chem 2001; 276:48389-97. [PMID: 11602600 DOI: 10.1074/jbc.m108210200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Caveolin-1 is a 22-kDa integral membrane protein that has been suggested to function as a negative regulator of mitogen-stimulated proliferation in a variety of cell types, including mammary epithelial cells. Because much of our insight into caveolin-1 function has come from the study of human breast tumor-derived cell lines in culture, the normal physiological regulators of caveolin-1 expression in the mammary gland remain unknown. Here, we examine caveolin-1 expression in mice at different stages of mammary gland development. We show that caveolin-1 expression is significantly down-regulated during late pregnancy and lactation. Upon weaning, mammary gland expression of caveolin-1 rapidly returns to non-pregnant "steady-state" levels. Injection of virgin mice with a battery of hormones normally up-regulated during lactation demonstrates that prolactin is the main mediator of caveolin-1 down-regulation. Virtually identical results were obtained with human mammary epithelial cells (hTERT-HME1) in culture. In addition, we demonstrate that prolactin-mediated down-regulation of caveolin-1 expression occurs at the level of transcriptional control and via a Ras-dependent mechanism. Interestingly, in the mammary gland, both mammary epithelial cells and the surrounding mammary adipocytes show prolactin-mediated down-regulation of caveolin-1. This hormone-dependent regulation of caveolin-1 expression is specific to the mammary fat pad. Finally, we employed HC11 cells, a well-established model of mammary epithelial cell differentiation, to study the possible functional effects of caveolin-1 expression. In the presence of lactogenic hormones, recombinant expression of caveolin-1 in HC11 cells dramatically suppresses the induction of the promoter activity and the synthesis of beta-casein, an established reporter of lactogenic differentiation and milk production. These findings may explain why caveolin-1 levels are normally down-regulated during lactation. This report is the first demonstration that caveolin-1 levels are down-regulated during a normal physiological event in vivo, i.e. lactation, because previous reports have only documented that down-regulation of caveolin-1 occurs during cell transformation and tumorigenesis.
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Affiliation(s)
- D S Park
- Department of Molecular Pharmacology, The Albert Einstein Comprehensive Cancer Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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Prigent-Tessier A, Barkai U, Tessier C, Cohen H, Gibori G. Characterization of a rat uterine cell line, U(III) cells: prolactin (PRL) expression and endogenous regulation of PRL-dependent genes; estrogen receptor beta, alpha(2)-macroglobulin, and decidual PRL involving the Jak2 and Stat5 pathway. Endocrinology 2001; 142:1242-50. [PMID: 11181541 DOI: 10.1210/endo.142.3.8004] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Decidualization of endometrial stroma in the rat induces the expression and secretion of rat decidual PRL (rdPRL). Recently, we have generated a nontransformed rat uterine stromal cell line (U(III)) that decidualizes spontaneously in culture. In this report, we have established by immunocytochemistry, RT-PCR, Western blot analysis, labeled amino acid incorporation and RIA that these cells express the rat PRL messenger RNA as well as synthesize and secrete PRL. We have also cloned by RT-PCR a 403-bp complementary DNA fragment whose sequence is identical with that of rat pituitary PRL. In addition, U(III) cells express the PRL receptor (PRL-R) long form, all the components involved in the PRL signal transduction pathway, estrogen receptor beta (ER beta) and alpha(2)-macroglobulin (alpha(2)-MG), which are known to be PRL-regulated genes. However, when U(III) cells were treated with PRL, no regulation of these genes was observed. Moreover, in these cells, the PRL signaling components: the tyrosine kinase Jak2 and the transcription factor Stat5 were endogenously phosphorylated and their phosphorylation states were not enhanced in the presence of exogenous PRL. To examine whether the endogenously secreted PRL affects the expression of PRL-regulated genes, U(III) cells were treated with either an anti-PRL receptor antibody or a Jak2 inhibitor, AG490. The anti-PRL receptor antibody decreased alpha(2)-MG expression. AG490 inhibited Jak2 and Stat5 phosphorylation, prevented Stat5 binding to its DNA consensus sequence, and also caused a dose-dependent down-regulation of alpha(2)-MG and ER beta expression. In contrast, AG490 enhanced PRL mRNA levels. In summary, we have established that the U(III) stromal cells of uterine origin produce PRL. Furthermore, we have shown for the first time that decidual PRL may act locally to activate the Jak2/Stat5 pathway and up-regulate important genes involved in decidual growth and placentation.
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Affiliation(s)
- A Prigent-Tessier
- Department of Physiology and Biophysics, College of Medicine, University of Illinois, Chicago, Illinois 60612, USA
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20
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Osamura RY, Iwasaka T, Umemura S. Endocrine System and Endocrine Disrupting Chemicals(EDCs). J Toxicol Pathol 2001. [DOI: 10.1293/tox.14.59] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
| | - Toshiki Iwasaka
- Department of Pathology, Tokai University School of Medicine
| | - Shinobu Umemura
- Department of Pathology, Tokai University School of Medicine
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Freeman ME, Kanyicska B, Lerant A, Nagy G. Prolactin: structure, function, and regulation of secretion. Physiol Rev 2000; 80:1523-631. [PMID: 11015620 DOI: 10.1152/physrev.2000.80.4.1523] [Citation(s) in RCA: 1463] [Impact Index Per Article: 61.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Prolactin is a protein hormone of the anterior pituitary gland that was originally named for its ability to promote lactation in response to the suckling stimulus of hungry young mammals. We now know that prolactin is not as simple as originally described. Indeed, chemically, prolactin appears in a multiplicity of posttranslational forms ranging from size variants to chemical modifications such as phosphorylation or glycosylation. It is not only synthesized in the pituitary gland, as originally described, but also within the central nervous system, the immune system, the uterus and its associated tissues of conception, and even the mammary gland itself. Moreover, its biological actions are not limited solely to reproduction because it has been shown to control a variety of behaviors and even play a role in homeostasis. Prolactin-releasing stimuli not only include the nursing stimulus, but light, audition, olfaction, and stress can serve a stimulatory role. Finally, although it is well known that dopamine of hypothalamic origin provides inhibitory control over the secretion of prolactin, other factors within the brain, pituitary gland, and peripheral organs have been shown to inhibit or stimulate prolactin secretion as well. It is the purpose of this review to provide a comprehensive survey of our current understanding of prolactin's function and its regulation and to expose some of the controversies still existing.
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Affiliation(s)
- M E Freeman
- Department of Biological Science, Florida State University, Tallahassee, Florida 32306-4340, USA.
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Iwasaka T, Umemura S, Kakimoto K, Koizumi H, Osamura YR. Expression of prolactin mRNA in rat mammary gland during pregnancy and lactation. J Histochem Cytochem 2000; 48:389-96. [PMID: 10681392 DOI: 10.1177/002215540004800308] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
We studied the expression of prolactin (PRL) mRNA in the mammary gland of resting, pregnant, lactating, and weanling rats using in situ and solution reverse transcriptase-polymerase chain reaction (RT-PCR). In mid- to late pregnancy and throughout lactation, PRL mRNA was detected in both in situ and solution RT-PCR. These PRL mRNA signals were clearly identified in the cytoplasm of alveolar and ductal mammary epithelial cells by the in situ RT-PCR method. In mid- to late pregnancy, such as at the initiating point of PRL mRNA expression, we confirmed in some cases a lack of PRL mRNA by solution RT-PCR. In addition, in the early weaning phase, no signals were detected by solution RT-PCR. However, slight focal signals were detected in some poorly vacuolated cytoplasm of regressing acinar cells by in situ RT-PCR. These findings suggest that PRL mRNA in rat mammary gland begins in mid- to late pregnancy in parallel with the development of the mammary gland, continues throughout lactation, and declines in the early phase of weaning, with regression of mammary epithelial cells.
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Affiliation(s)
- T Iwasaka
- Department of Pathology, Tokai University School of Medicine, Kanagawa, Japan
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24
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Abstract
This review will focus on the role for prolactin (PRL) and growth hormone (GH) in mammary tumor formation. Much attention has previously been focused on circulating levels of GH/PRL in relation to mammary tumor formation. We will review data demonstrating that these ligands also could be produced locally in different organs, including the mammary gland and mammary tumors, and suggest that this local production may be of importance for pathological conditions. We will also discuss mechanisms for crosstalk between steroids and GH/PRL. A crosstalk between GH- and PRL response is possible at multiple levels. In the human, GH can activate both the prolactin receptor (PRLR) and the growth hormone receptor (GHR). We have demonstrated that activation of the PRLR, but not the GHR, is inducing mammary tumors in transgenic mice. Furthermore, the elevated levels of insulin-like growth factor 1 (IGF-I) seen in the GHR activating transgenic mice is not sufficient for tumor induction. The induced tumors express functionally active prolactin that could be of importance for the tumor formation. Paracrine/aurocrine stimulation by PRL may be more important than PRL transported via the circulation. In women, the role for stimulation of the PRLR and/or the GHR in mammary tumor formation has not been proven, although experiments from primates suggest that the PRLR could be of importance.
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Affiliation(s)
- H Wennbo
- Astra Transgenic Centre, Mölndal, Sweden
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25
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Iwasaka T, Umemura S, Miyajima K, Shoda T, Takahashi A, Kakimoto K, Koizumi H, Miyakawa Y, Osamura YR. Lack of Prolactin (PRL) mRNA Expression in Estrogen-treated Rat Mammary Glands. J Toxicol Pathol 2000. [DOI: 10.1293/tox.13.151] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Toshiki Iwasaka
- Department of Pathology, Tokai University School of Medicine, Isehara, Kanagawa, 259-1193, Japan
- Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23-Nakogi, Hadano, Kanagawa, 257-0024, Japan
| | - Shinobu Umemura
- Department of Pathology, Tokai University School of Medicine, Isehara, Kanagawa, 259-1193, Japan
| | - Katsuhiro Miyajima
- Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23-Nakogi, Hadano, Kanagawa, 257-0024, Japan
| | - Toshiyuki Shoda
- Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23-Nakogi, Hadano, Kanagawa, 257-0024, Japan
| | - Akemi Takahashi
- Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23-Nakogi, Hadano, Kanagawa, 257-0024, Japan
| | - Kochi Kakimoto
- Department of Pathology, Tokai University School of Medicine, Isehara, Kanagawa, 259-1193, Japan
- Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23-Nakogi, Hadano, Kanagawa, 257-0024, Japan
| | - Haruko Koizumi
- Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23-Nakogi, Hadano, Kanagawa, 257-0024, Japan
| | - Yoshifumi Miyakawa
- Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23-Nakogi, Hadano, Kanagawa, 257-0024, Japan
| | - Yoshiyuki R Osamura
- Department of Pathology, Tokai University School of Medicine, Isehara, Kanagawa, 259-1193, Japan
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Santos CR, Brinca L, Ingleton PM, Power DM. Cloning, expression, and tissue localisation of prolactin in adult sea bream (Sparus aurata). Gen Comp Endocrinol 1999; 114:57-66. [PMID: 10094859 DOI: 10.1006/gcen.1998.7228] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A major action of prolactin (PRL) in teleost fish is the maintenance of hydromineral balance in euryhaline species in fresh water. The function of PRL in marine teleosts is less certain and unlike euryhaline teleosts, such as tilapia and salmon, there is relatively little information about protein or gene structure. Associated with studies to determine potential functions of PRL, pituitary prolactin cDNA has been cloned and sequenced from sea bream (Sparus aurata), a marine teleost. The sequence obtained spanned 1349 bp and contained an open reading frame encoding a protein of 212 amino acids composed of a putative signal peptide of 24 residues and a mature protein of 188 amino acids. N-terminal sequencing of the native protein confirmed unambiguously the cleavage site, Ala24, Val25, predicted from alignments of the sea bream PRL cDNA with that of other teleosts. The presence of only one form of PRL in sea bream was supported by identification using Northern blots of only a single transcript of 1.35 kb. Reverse transcription and polymerase chain reaction techniques coupled with Southern blot analysis resulted in the detection of PRL in the pituitary but also in the intestine, liver, ovary, and testes.
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Affiliation(s)
- C R Santos
- Centro de Ciências do Mar, Campus de Gambelas, Faro, 8000, Portugal
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27
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Abstract
BACKGROUND Prolactin (PRL), originally identified as an anterior pituitary hormone exhibiting lactogenic activity, is now recognized as a versatile hormone expressed in a wide variety of tissues. METHODS In this study, the expression of PRL in the mouse kidney was investigated by solution-phase and in situ reverse transcription-polymerase chain reaction (RT-PCR) methods and immunohistochemistry. RESULTS Mouse PRL (mPRL) transcript and protein are localized in the parietal epithelial cells of Bowman's capsule. Pit-1 is a positive transcription factor for the expression of the PRL gene. The presence of Pit-1 transcript in the kidney was also assessed by RT-PCR methods. The localization of Pit-1 mRNA coincided well with that of PRL. Immunoreactivity to mouse PRL receptor (mPRL-R) is distributed on the luminal membrane of the proximal tubule cells and the parietal epithelial cells of Bowman's capsule. CONCLUSION These data indicate that the parietal epithelial cells of Bowman's capsule synthesize PRL de novo and suggest that Pit-1 contributes to the transcriptional regulation of PRL gene expression in the kidney, and PRL expressed in this tissue functions in an autocrine/paracrine fashion.
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Affiliation(s)
- Y Sakai
- Department of Anatomy, Keio University School of Medicine, Tokyo, Japan
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Abstract
Prolactin (PRL) is both a mitogen and a differentiating agent in the mammary gland. It has been shown to be involved in mammary cancer development in rodents, but in human breast cancer, its role has long been overlooked. Three criteria are applied to demonstrate PRL's involvement in this disease: (1) PRL receptors are present in human breast cancer cells, (2) human breast cancer cells in culture respond to PRL as a mitogen, and (3) PRL is synthesized by human breast cancer cells and inhibition of the binding of PRL to its receptors inhibits cell growth.
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Affiliation(s)
- B K Vonderhaar
- Molecular and Cellular Endocrinology Section, Laboratory of Tumor Immunology and Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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29
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Touraine P, Martini JF, Zafrani B, Durand JC, Labaille F, Malet C, Nicolas A, Trivin C, Postel-Vinay MC, Kuttenn F, Kelly PA. Increased expression of prolactin receptor gene assessed by quantitative polymerase chain reaction in human breast tumors versus normal breast tissues. J Clin Endocrinol Metab 1998; 83:667-74. [PMID: 9467590 DOI: 10.1210/jcem.83.2.4564] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The role of PRL in human breast tumorigenesis is not well understood. One of the limitations is the difficulty of accurately measuring PRL receptors (PRLR) in human tissues. We established a quantitative PCR method (Q-PCR) in T-47D human breast cancer cells and applied it to 29 patients, 25 of whom presented with either cancer or fibroadenoma. Four patients underwent a mammoplasty, and normal epithelial cells were cultured before Q-PCR. In T-47D cells, 31 x 10(6) messenger RNA molecules were detected per microgram of total RNA. In all patients, expression of the PRLR gene was detected, varying from 1500 to 1 x 10(6) molecules/microgram of RNA in normal tissues and from 4500 to 34.7 x 10(6) molecules/microgram of RNA in tumors. PRLR expression was always greater in tumor than in normal contiguous tissue and similar in cultured mammary epithelial cells and normal breast tissues. Estradiol and progesterone receptor-negative tumors expressed low levels of PRLR transcripts, similar to normal breast tissue from menopausal women. Immunocytochemical analysis of PRLR confirmed stronger staining in almost all tumor samples compared with normal tissues. A messenger RNA encoding locally produced human PRL was also identified by RT-PCR in every sample tested. Our results confirm PRLR gene expression in all tissues studied, and moreover, indicate that this expression is increased in human breast tumors vs. normal contiguous tissues.
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Affiliation(s)
- P Touraine
- INSERM Unité 344, Faculté Medecine Necker, Paris, France
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31
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Shaw-Bruha CM, Pirrucello SJ, Shull JD. Expression of the prolactin gene in normal and neoplastic human breast tissues and human mammary cell lines: promoter usage and alternative mRNA splicing. Breast Cancer Res Treat 1997; 44:243-53. [PMID: 9266104 DOI: 10.1023/a:1005879103367] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Prolactin (PRL) has been implicated in the development of mammary cancer in rodents and humans. Although PRL and its mRNA have been detected in breast tissues and some mammary cell lines, the role of PRL as an autocrine/paracrine growth factor within the breast is not clear. A second, more distal, promoter has recently been identified in the human PRL gene. We have used reverse transcription-polymerase chain reaction (RT-PCR) to determine whether the distal or the proximal promoter directs expression of the PRL gene in normal and neoplastic breast tissues and in mammary cell lines. Total RNA was isolated from 10 normal and 20 neoplastic breast tissue samples and from 8 mammary cell lines; MDA-MB-231, SK-BR-3, T-47D, MCF10, MCF10T2, and 3 MCF7 derivatives. The RNA was reverse transcribed to cDNA using random hexamers as primers. PCR amplification of the cDNAs was performed, using a variety of PRL-specific primer pairs, and the DNA products were subjected to agarose gel electrophoresis and Southern blotting. The resulting data indicate that the PRL gene is expressed in the majority of both normal and neoplastic breast tissue samples, as well as all of the mammary cell lines. PRL-specific PCR products corresponding to transcripts that originated from the distal promoter were observed in a subset of the normal and neoplastic breast tissue samples and mammary cell lines. Together these data indicate that PRL transcripts in human breast tissues and human mammary cell lines originate, at least in part, from the distal PRL promoter. In addition, data are presented which suggest that PRL transcripts in breast tissues and mammary cell lines may undergo alternative splicing.
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Affiliation(s)
- C M Shaw-Bruha
- Eppley Institute for Research in Cancer and Allied Diseases, Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha 68198-6805, USA
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Tao YX, Lei ZM, Rao CV. The presence of luteinizing hormone/human chorionic gonadotropin receptors in lactating rat mammary glands. Life Sci 1997; 60:1297-303. [PMID: 9096247 DOI: 10.1016/s0024-3205(97)00073-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Previous studies have implied that mammary glands might contain luteinizing hormone (LH)/human chorionic gonadotropin (hCG) receptors. But no one ever previously investigated them. We now demonstrate, by using several techniques, that lactating rat mammary glands contain LH/hCG receptor mRNA transcripts and receptor protein which can bind 125I-hCG. Primarily mammary epithelial cells, and to a lesser extent the interductal stromal cells, contain the receptor transcripts and the receptor protein. These findings support the concept that mammary glands are also the targets of direct regulation by LH/hCG.
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Affiliation(s)
- Y X Tao
- Department of Obstetrics and Gynecology, University of Louisville School of Medicine, Kentucky 40292, U.S.A
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33
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Abstract
The neuroendocrine hormone prolactin (PRL) stimulates breast growth and differentiation during puberty, pregnancy, and lactation. Despite extensive and convincing data indicating that PRL significantly contributes to the pathogenesis and progression of rodent mammary carcinoma, parallel observations for human breast cancer have not been concordant. In particular, the therapeutic alteration of somatolactogenic hormone levels has not consistently altered the course of human breast cancer. Recent data, however, suggest that extra-pituitary tissues are capable of elaborating PRL; indeed, the observation of sustained serum levels of PRL in post-hypophysectomy patients supports this hypothesis. Proof of an autocrine/paracrine loop for PRL within normal and malignant human breast tissues requires that the following three criteria be met: (1) PRL must be synthesized and secreted within mammary tissues; (2) the receptor for PRL (PRLR) must be present within these tissues; and, (3) proliferative responses to autocrine/paracrine PRL must be demonstrated. These criteria have now been fulfilled in several laboratories. With the demonstration of a PRL autocrine/paracrine loop in mammary glands, the basis for the ineffective treatment of human breast cancer by prior endocrine-based anti-somatolactogenic therapies is evident. These findings provide the precedent for novel therapeutic strategies aimed at interrupting the stimulation of breast cancer growth by PRL at both endocrine and autocrine/paracrine levels.
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Affiliation(s)
- C V Clevenger
- Department of Pathology and Laboratory Medicine, University of Pennsylvania Medical Center, Philadelphia 19104, USA.
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Abstract
Milk is primarily regarded as a food furnishing essential nutrients for infant growth and development, but milk can also serve as a vehicle for mother to neonate transfer of molecules that regulate development. A wide array of biologically active compounds such as hormones, cytokines and enzymes are present in milk, especially early milk. The premise that prolactin (PRL) in milk is an important and possibly essential developmental factor for the newborn is explored. Both PRL and structurally modified isoforms are abundant in early milk and gradually diminish with the progression of lactation. Milk PRL is absorbed and biologically active in the neonate. Assays of PRL variants, experimental paradigms to test them as developmental regulators and the body of evidence supporting the hypothesis that milk PRL regulates differentiation and maturation of neonatal neuroendocrine, reproductive, and immune systems is presented.
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Affiliation(s)
- L A Ellis
- Department of Nutrition, Pennsylvania State University, University Park 16802, USA
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35
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Darcy KM, Shoemaker SF, Lee PP, Vaughan MM, Black JD, Ip MM. Prolactin and epidermal growth factor regulation of the proliferation, morphogenesis, and functional differentiation of normal rat mammary epithelial cells in three dimensional primary culture. J Cell Physiol 1995; 163:346-64. [PMID: 7706378 DOI: 10.1002/jcp.1041630216] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The epithelial cell-specific effects of prolactin and epidermal growth factor (EGF) on the development of normal rat mammary epithelial cells (MEC) were evaluated using a three dimensional primary culture model developed in our laboratory. Non-milk-producing MEC were isolated as spherical end bud-like mammary epithelial organoids (MEO) from pubescent virgin female rats. The cultured MEO developed into elaborate multilobular and lobuloductal alveolar organoids composed of cytologically and functionally differentiated MEC. Prolactin (0.01-10 micrograms/ml) and EGF (1-100 ng/ml) were each required for induction of cell growth, extensive alveolar, as well as multilobular branching morphogenesis, and casein accumulation. MEO cultured without prolactin for 14 days remained sensitive to the mitogenic, morphogenic, and lactogenic effects of prolactin upon subsequent exposure. Similarly, cells cultured in the absence of EGF remained sensitive to the mitogenic and lactogenic effects of EGF, but were less responsive to its morphogenic effects when it was added on day 14 of a 21-day culture period. If exposure to prolactin was terminated after the first week, the magnitude of the mitogenic and lactogenic effects, but not the morphogenic response was decreased. Removal of EGF on day 7 also reduced the mitogenic response, but did not have any effect on the magnitude of the lactogenic or morphogenic responses. These studies demonstrate that physiologically relevant development of normal MEC can be induced in culture and that this model system can be used to study the mechanisms by which prolactin and EGF regulate the complex developmental pathways operative in the mammary gland.
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Affiliation(s)
- K M Darcy
- Grace Cancer Drug Center, Roswell Park Cancer Institute, Buffalo, New York 14263, USA
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Bredow S, Kacsóh B, Obál F, Fang J, Krueger JM. Increase of prolactin mRNA in the rat hypothalamus after intracerebroventricular injection of VIP or PACAP. Brain Res 1994; 660:301-8. [PMID: 7820699 DOI: 10.1016/0006-8993(94)91303-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Vasoactive intestinal peptide (VIP), the structurally homologous pituitary adenylate cyclase-activating peptide (PACAP) and the pituitary hormone, prolactin (PRL) enhance rapid eye movement sleep (REMS). VIP and PACAP are both inducers of PRL gene expression and release in the pituitary gland. Little is known about PRL regulation in the brain although it is hypothesized that the REMS-promoting activity of i.c.v. administered VIP may be mediated via the activation of cerebral PRL. To test whether VIP or PACAP in fact increase intracerebral mRNA, the peptides (VIP: 30 or 300 pmol; PACAP: 220 pmol) were injected i.c.v. into rats at dark onset. 1 h later, cDNA was synthesized from purified hypothalamic mRNA. Standardized amounts were analysed for PRL using the polymerase chain reaction followed by Southern blotting and hybridization. Compared with beta-actin mRNA levels, both VIP and PACAP increased PRL mRNA levels in a dose-dependent fashion though VIP was more effective on a molar basis. The previously reported alternatively spliced PRL mRNA (lacking exon 4) was not detected. The data support the hypothesis that the REMS-promoting activity of central VIP and PACAP might be mediated by cerebral PRL.
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Affiliation(s)
- S Bredow
- Department of Physiology and Biophysics, University of Tennessee at Memphis 38163
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37
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Gourdji D, Laverrière JN. The rat prolactin gene: a target for tissue-specific and hormone-dependent transcription factors. Mol Cell Endocrinol 1994; 100:133-42. [PMID: 7914498 DOI: 10.1016/0303-7207(94)90292-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- D Gourdji
- Groupe de Biologie de la Cellule Neuroendocrine, CNRS URA 1115, Collège de France, Paris
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