1
|
Menendez JA, Peirce SK, Papadimitropoulou A, Cuyàs E, Steen TV, Verdura S, Vellon L, Chen WY, Lupu R. Progesterone receptor isoform-dependent cross-talk between prolactin and fatty acid synthase in breast cancer. Aging (Albany NY) 2020; 12:24671-24692. [PMID: 33335078 PMCID: PMC7803566 DOI: 10.18632/aging.202289] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 10/27/2020] [Indexed: 04/13/2023]
Abstract
Progesterone receptor (PR) isoforms can drive unique phenotypes in luminal breast cancer (BC). Here, we hypothesized that PR-B and PR-A isoforms differentially modify the cross-talk between prolactin and fatty acid synthase (FASN) in BC. We profiled the responsiveness of the FASN gene promoter to prolactin in T47Dco BC cells constitutively expressing PR-A and PR-B, in the PR-null variant T47D-Y cell line, and in PR-null T47D-Y cells engineered to stably re-express PR-A (T47D-YA) or PR-B (T47D-YB). The capacity of prolactin to up-regulate FASN gene promoter activity in T47Dco cells was lost in T47D-Y and TD47-YA cells. Constitutively up-regulated FASN gene expression in T47-YB cells and its further stimulation by prolactin were both suppressed by the prolactin receptor antagonist hPRL-G129R. The ability of the FASN inhibitor C75 to decrease prolactin secretion was more conspicuous in T47-YB cells. In T47D-Y cells, which secreted notably less prolactin and downregulated prolactin receptor expression relative to T47Dco cells, FASN blockade resulted in an augmented secretion of prolactin and up-regulation of prolactin receptor expression. Our data reveal unforeseen PR-B isoform-specific regulatory actions in the cross-talk between prolactin and FASN signaling in BC. These findings might provide new PR-B/FASN-centered predictive and therapeutic modalities in luminal intrinsic BC subtypes.
Collapse
MESH Headings
- 4-Butyrolactone/analogs & derivatives
- 4-Butyrolactone/pharmacology
- Breast Neoplasms/genetics
- Breast Neoplasms/metabolism
- Carcinoma, Ductal, Breast/genetics
- Carcinoma, Ductal, Breast/metabolism
- Cell Line, Tumor
- Databases, Genetic
- Fatty Acid Synthase, Type I/antagonists & inhibitors
- Fatty Acid Synthase, Type I/genetics
- Fatty Acid Synthase, Type I/metabolism
- Humans
- Interleukin-6/metabolism
- Prolactin/metabolism
- Prolactin/pharmacology
- Promoter Regions, Genetic
- Protein Isoforms
- RNA, Messenger/metabolism
- Receptor Cross-Talk
- Receptors, Progesterone/genetics
- Receptors, Progesterone/metabolism
- Receptors, Prolactin/antagonists & inhibitors
- Receptors, Prolactin/genetics
- Receptors, Prolactin/metabolism
- Up-Regulation
Collapse
Affiliation(s)
- Javier A. Menendez
- Program Against Cancer Therapeutic Resistance (ProCURE), Metabolism and Cancer Group, Catalan Institute of Oncology, Girona, Spain
- Girona Biomedical Research Institute (IDIBGI), Girona, Spain
| | | | | | - Elisabet Cuyàs
- Program Against Cancer Therapeutic Resistance (ProCURE), Metabolism and Cancer Group, Catalan Institute of Oncology, Girona, Spain
- Girona Biomedical Research Institute (IDIBGI), Girona, Spain
| | - Travis Vander Steen
- Mayo Clinic, Division of Experimental Pathology, Department of Laboratory Medicine and Pathology, Rochester, MN 55905, USA
| | - Sara Verdura
- Program Against Cancer Therapeutic Resistance (ProCURE), Metabolism and Cancer Group, Catalan Institute of Oncology, Girona, Spain
- Girona Biomedical Research Institute (IDIBGI), Girona, Spain
| | - Luciano Vellon
- Stem Cells Laboratory, Institute of Biology and Experimental Medicine (IBYME-CONICET), Buenos Aires, Argentina
| | - Wen Y. Chen
- Department of Biological Sciences, Clemson University, Greenville, SC 29634, USA
| | - Ruth Lupu
- Mayo Clinic, Division of Experimental Pathology, Department of Laboratory Medicine and Pathology, Rochester, MN 55905, USA
- Mayo Clinic Minnesota, Department of Biochemistry and Molecular Biology Laboratory, Rochester, MN 55905, USA
- Mayo Clinic Cancer Center, Rochester, MN 55905, USA
| |
Collapse
|
2
|
Asad AS, Nicola Candia AJ, Gonzalez N, Zuccato CF, Seilicovich A, Candolfi M. The role of the prolactin receptor pathway in the pathogenesis of glioblastoma: what do we know so far? Expert Opin Ther Targets 2020; 24:1121-1133. [PMID: 32896197 DOI: 10.1080/14728222.2020.1821187] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Introduction: Prolactin (PRL) and its receptor (PRLR) have been associated with the development of hormone-dependent tumors and have been detected in glioblastoma (GBM) biopsies. GBM is the most common and aggressive primary brain tumor in adults and the prognosis for patients is dismal; hence researchers are exploring the PRLR pathway as a therapeutic target in this disease. Areas covered: This paper explores the effects of PRLR activation on the biology of GBM, the correlation between PRL and PRLR expression and GBM progression and survival in male and female patients. Finally, we discuss how a better understanding of the PRLR pathway may allow the development of novel treatments for GBM. Expert opinion: We propose PRL and PRLR as potential prognosis biomarkers and therapeutic targets in GBM. Local administration of PRLR inhibitors using gene therapy may offer a beneficial strategy for targeting GBM cells disseminated in the non-neoplastic brain; however, efficacy and safety require careful and extensive evaluation. The data depicted herein underline the need to (i) improve our understanding of sexual dimorphism in GBM, and (ii) develop accurate preclinical models that take into consideration different hormonal contexts, specific genetic alterations, and tumor grades.
Collapse
Affiliation(s)
- Antonela S Asad
- Instituto de Investigaciones Biomédicas (INBIOMED, UBA-CONICET), Facultad de Medicina, Universidad de Buenos Aires , Buenos Aires, Argentina
| | - Alejandro J Nicola Candia
- Instituto de Investigaciones Biomédicas (INBIOMED, UBA-CONICET), Facultad de Medicina, Universidad de Buenos Aires , Buenos Aires, Argentina
| | - Nazareno Gonzalez
- Instituto de Investigaciones Biomédicas (INBIOMED, UBA-CONICET), Facultad de Medicina, Universidad de Buenos Aires , Buenos Aires, Argentina
| | - Camila F Zuccato
- Instituto de Investigaciones Biomédicas (INBIOMED, UBA-CONICET), Facultad de Medicina, Universidad de Buenos Aires , Buenos Aires, Argentina
| | - Adriana Seilicovich
- Instituto de Investigaciones Biomédicas (INBIOMED, UBA-CONICET), Facultad de Medicina, Universidad de Buenos Aires , Buenos Aires, Argentina.,departamento de Biología Celular e Histología, Facultad de Medicina, Universidad de Buenos Aires , Buenos Aires, Argentina
| | - Marianela Candolfi
- Instituto de Investigaciones Biomédicas (INBIOMED, UBA-CONICET), Facultad de Medicina, Universidad de Buenos Aires , Buenos Aires, Argentina
| |
Collapse
|
3
|
Zhang Y, Gc S, Patel SB, Liu Y, Paterson AJ, Kappes JC, Jiang J, Frank SJ. Growth hormone (GH) receptor (GHR)-specific inhibition of GH-Induced signaling by soluble IGF-1 receptor (sol IGF-1R). Mol Cell Endocrinol 2019; 492:110445. [PMID: 31100495 PMCID: PMC6613819 DOI: 10.1016/j.mce.2019.05.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 05/06/2019] [Accepted: 05/07/2019] [Indexed: 12/31/2022]
Abstract
Human growth hormone (GH) binds and activates GH receptor (GHR) and prolactin (PRL) receptor (PRLR). LNCaP human prostate cancer cells express only GHR. A soluble fragment of IGF-1 receptor (IGF-1R) extracellular domain (sol IGF-1R) interacts with GHR and blocks GH signaling. We now explore sol IGF-1R's specificity for inhibiting GH signaling via GHR vs. PRLR and test GHR and PRLR extracellular domain inhibition determinants. Although T47D human breast cancer cells express GHR and PRLR, GH signaling is largely PRLR-mediated. In T47D, sol IGF-1R inhibited neither GH- nor PRL-induced STAT5 activation. However, sol IGF-1R inhibited GH-induced STAT5 activation in T47D-shPRLR cells, which harbor reduced PRLR. In MIN6 mouse β-cells, bovine GH (bGH) activates mouse GHR, not PRLR, while human GH activates mouse GHR and PRLR. In MIN6, sol IGF-1R inhibited bGH-induced STAT5 activation, but partially inhibited human GH-induced STAT5 activation. These findings suggest sol IGF-1R's inhibition is GHR-specific. Using a cellular reconstitution system, we compared effects of sol IGF-1R on signaling through GHR, PRLR, or chimeras in which extracellular subdomains 2 (S2) of the receptors were swapped. Sol IGF-1R inhibited GH-induced STAT5 activation in GHR-expressing, not PRLR-expressing cells, consistent with GHR specificity of sol IGF-1R. Interestingly, we found that GHR S2 (which harbors the GHR-GHR dimer interface) was required, but not sufficient for sol IGF-1R inhibition of GHR signaling. These results suggest sol IGF-1R specifically inhibits GH-induced GHR-mediated signaling, possibly through interaction with GHR S1 and S2 domains. Our findings have implications for GH antagonist development.
Collapse
Affiliation(s)
- Yue Zhang
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Sajina Gc
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Sweta B Patel
- Department of Medicine, Division of Hematology and Oncology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Ying Liu
- School of Medicine, University of Pittsburgh, Pittsburgh, PA, 15261, USA
| | - Andrew J Paterson
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - John C Kappes
- Department of Medicine, Division of Hematology and Oncology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Jing Jiang
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Stuart J Frank
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, AL, 35294, USA; Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA; Endocrinology Section, Medical Service, Veterans Affairs Medical Center, Birmingham, AL, 35233, USA.
| |
Collapse
|
4
|
Basu R, Wu S, Kopchick JJ. Targeting growth hormone receptor in human melanoma cells attenuates tumor progression and epithelial mesenchymal transition via suppression of multiple oncogenic pathways. Oncotarget 2017; 8:21579-21598. [PMID: 28223541 PMCID: PMC5400608 DOI: 10.18632/oncotarget.15375] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 01/24/2017] [Indexed: 12/12/2022] Open
Abstract
Recent reports have confirmed highest levels of growth hormone (GH) receptor (GHR) transcripts in melanoma, one of the most aggressive forms of human cancer. Yet the mechanism of GH action in melanoma remains mostly unknown. Here, using human malignant melanoma cells, we examined the effects of GH excess or siRNA mediated GHR knock-down (GHRKD) on tumor proliferation, migration and invasion. GH promoted melanoma progression while GHRKD attenuated the same. Western blot analysis revealed drastic modulation of multiple oncogenic signaling pathways (JAK2, STAT1, STAT3, STAT5, AKT, mTOR, SRC and ERK1/2) following addition of GH or GHRKD. Further, we show that GH excess upregulates expression of markers of epithelial mesenchymal transition in human melanoma, while the effects were reversed by GHRKD. Interestingly, we observed consistent expression of GH transcript in the melanoma cells as well as marked modulation of the IGF receptors and binding proteins (IGF1R, IGF2R, IR, IGFBP2, IGFBP3) and the oncogenic HGF-MET mRNA, in response to excess GH or GHRKD. Our study thus identifies the mechanistic model of GH-GHR action in human melanoma and validates it as an important pharmacological target of intervention.
Collapse
Affiliation(s)
- Reetobrata Basu
- Edison Biotechnology Institute, Ohio University, Athens, Ohio, USA.,Molecular and Cell Biology Program, Ohio University, Athens, Ohio, USA
| | - Shiyong Wu
- Edison Biotechnology Institute, Ohio University, Athens, Ohio, USA.,Molecular and Cell Biology Program, Ohio University, Athens, Ohio, USA
| | - John J Kopchick
- Edison Biotechnology Institute, Ohio University, Athens, Ohio, USA.,Molecular and Cell Biology Program, Ohio University, Athens, Ohio, USA.,Ohio University Heritage College of Osteopathic Medicine, Athens, Ohio, USA
| |
Collapse
|
5
|
Liu Y, Zhang Y, Jiang J, Lobie PE, Paulmurugan R, Langenheim JF, Chen WY, Zinn KR, Frank SJ. GHR/PRLR Heteromultimer Is Composed of GHR Homodimers and PRLR Homodimers. Mol Endocrinol 2016; 30:504-17. [PMID: 27003442 DOI: 10.1210/me.2015-1319] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
GH receptor (GHR) and prolactin (PRL) receptor (PRLR) are homologous transmembrane cytokine receptors. Each prehomodimerizes and ligand binding activates Janus Kinase 2 (JAK2)-signal transducer and activator of transcription (STAT) signaling pathways by inducing conformational changes within receptor homodimers. In humans, GHR is activated by GH, whereas PRLR is activated by both GH and PRL. We previously devised a split luciferase complementation assay, in which 1 receptor is fused to an N-terminal luciferase (Nluc) fragment, and the other receptor is fused to a C-terminal luciferase (Cluc) fragment. When receptors approximate, luciferase activity (complementation) results. Using this assay, we reported ligand-independent GHR-GHR complementation and GH-induced complementation changes characterized by acute augmentation above basal signal, consistent with induction of conformational changes that bring GHR cytoplasmic tails closer. We also demonstrated association between GHR and PRLR in T47D human breast cancer cells by coimmunoprecipitation, suggesting that, in addition to forming homodimers, these receptors form hetero-assemblages with functional consequences. We now extend these analyses to examine basal and ligand-induced complementation of coexpressed PRLR-Nluc and PRLR-Cluc chimeras and coexpressed GHR-Nluc and PRLR-Cluc chimeras. We find that PRLR-PRLR and GHR-PRLR form specifically interacting ligand-independent assemblages and that either GH or PRL augments PRLR-PRLR complementation, much like the GH-induced changes in GHR-GHR dimers. However, in contrast to the complementation patterns for GHR-GHR or PRLR-PRLR homomers, both GH and PRL caused decline in luciferase activity for GHR-PRLR heteromers. These and other data suggest that GHR and PRLR associate in complexes comprised of GHR-GHR/PRLR-PRLR heteromers consisting of GHR homodimers and PRLR homodimers, rather than GHR-PRLR heterodimers.
Collapse
Affiliation(s)
- Ying Liu
- Department of Medicine (Y.L., Y.Z., J.J., S.J.F.), Division of Endocrinology, Diabetes, and Metabolism; Department of Radiology (K.R.Z.); and Department of Cell, Developmental, and Integrative Biology (S.J.F.), University of Alabama at Birmingham, Birmingham, Alabama 35294; Cancer Science Institute of Singapore and Department of Pharmacology (P.E.L.), National University of Singapore, Singapore 119077; Department of Radiology (R.P.), Stanford University School of Medicine, Palo Alto, California 94304; Department of Biological Sciences (J.F.L., W.Y.C.), Clemson University, Clemson, South Carolina 29634; and Endocrinology Section (S.J.F.), Medical Service, Veterans Affairs Medical Center, Birmingham, Alabama 35233
| | - Yue Zhang
- Department of Medicine (Y.L., Y.Z., J.J., S.J.F.), Division of Endocrinology, Diabetes, and Metabolism; Department of Radiology (K.R.Z.); and Department of Cell, Developmental, and Integrative Biology (S.J.F.), University of Alabama at Birmingham, Birmingham, Alabama 35294; Cancer Science Institute of Singapore and Department of Pharmacology (P.E.L.), National University of Singapore, Singapore 119077; Department of Radiology (R.P.), Stanford University School of Medicine, Palo Alto, California 94304; Department of Biological Sciences (J.F.L., W.Y.C.), Clemson University, Clemson, South Carolina 29634; and Endocrinology Section (S.J.F.), Medical Service, Veterans Affairs Medical Center, Birmingham, Alabama 35233
| | - Jing Jiang
- Department of Medicine (Y.L., Y.Z., J.J., S.J.F.), Division of Endocrinology, Diabetes, and Metabolism; Department of Radiology (K.R.Z.); and Department of Cell, Developmental, and Integrative Biology (S.J.F.), University of Alabama at Birmingham, Birmingham, Alabama 35294; Cancer Science Institute of Singapore and Department of Pharmacology (P.E.L.), National University of Singapore, Singapore 119077; Department of Radiology (R.P.), Stanford University School of Medicine, Palo Alto, California 94304; Department of Biological Sciences (J.F.L., W.Y.C.), Clemson University, Clemson, South Carolina 29634; and Endocrinology Section (S.J.F.), Medical Service, Veterans Affairs Medical Center, Birmingham, Alabama 35233
| | - Peter E Lobie
- Department of Medicine (Y.L., Y.Z., J.J., S.J.F.), Division of Endocrinology, Diabetes, and Metabolism; Department of Radiology (K.R.Z.); and Department of Cell, Developmental, and Integrative Biology (S.J.F.), University of Alabama at Birmingham, Birmingham, Alabama 35294; Cancer Science Institute of Singapore and Department of Pharmacology (P.E.L.), National University of Singapore, Singapore 119077; Department of Radiology (R.P.), Stanford University School of Medicine, Palo Alto, California 94304; Department of Biological Sciences (J.F.L., W.Y.C.), Clemson University, Clemson, South Carolina 29634; and Endocrinology Section (S.J.F.), Medical Service, Veterans Affairs Medical Center, Birmingham, Alabama 35233
| | - Ramasamy Paulmurugan
- Department of Medicine (Y.L., Y.Z., J.J., S.J.F.), Division of Endocrinology, Diabetes, and Metabolism; Department of Radiology (K.R.Z.); and Department of Cell, Developmental, and Integrative Biology (S.J.F.), University of Alabama at Birmingham, Birmingham, Alabama 35294; Cancer Science Institute of Singapore and Department of Pharmacology (P.E.L.), National University of Singapore, Singapore 119077; Department of Radiology (R.P.), Stanford University School of Medicine, Palo Alto, California 94304; Department of Biological Sciences (J.F.L., W.Y.C.), Clemson University, Clemson, South Carolina 29634; and Endocrinology Section (S.J.F.), Medical Service, Veterans Affairs Medical Center, Birmingham, Alabama 35233
| | - John F Langenheim
- Department of Medicine (Y.L., Y.Z., J.J., S.J.F.), Division of Endocrinology, Diabetes, and Metabolism; Department of Radiology (K.R.Z.); and Department of Cell, Developmental, and Integrative Biology (S.J.F.), University of Alabama at Birmingham, Birmingham, Alabama 35294; Cancer Science Institute of Singapore and Department of Pharmacology (P.E.L.), National University of Singapore, Singapore 119077; Department of Radiology (R.P.), Stanford University School of Medicine, Palo Alto, California 94304; Department of Biological Sciences (J.F.L., W.Y.C.), Clemson University, Clemson, South Carolina 29634; and Endocrinology Section (S.J.F.), Medical Service, Veterans Affairs Medical Center, Birmingham, Alabama 35233
| | - Wen Y Chen
- Department of Medicine (Y.L., Y.Z., J.J., S.J.F.), Division of Endocrinology, Diabetes, and Metabolism; Department of Radiology (K.R.Z.); and Department of Cell, Developmental, and Integrative Biology (S.J.F.), University of Alabama at Birmingham, Birmingham, Alabama 35294; Cancer Science Institute of Singapore and Department of Pharmacology (P.E.L.), National University of Singapore, Singapore 119077; Department of Radiology (R.P.), Stanford University School of Medicine, Palo Alto, California 94304; Department of Biological Sciences (J.F.L., W.Y.C.), Clemson University, Clemson, South Carolina 29634; and Endocrinology Section (S.J.F.), Medical Service, Veterans Affairs Medical Center, Birmingham, Alabama 35233
| | - Kurt R Zinn
- Department of Medicine (Y.L., Y.Z., J.J., S.J.F.), Division of Endocrinology, Diabetes, and Metabolism; Department of Radiology (K.R.Z.); and Department of Cell, Developmental, and Integrative Biology (S.J.F.), University of Alabama at Birmingham, Birmingham, Alabama 35294; Cancer Science Institute of Singapore and Department of Pharmacology (P.E.L.), National University of Singapore, Singapore 119077; Department of Radiology (R.P.), Stanford University School of Medicine, Palo Alto, California 94304; Department of Biological Sciences (J.F.L., W.Y.C.), Clemson University, Clemson, South Carolina 29634; and Endocrinology Section (S.J.F.), Medical Service, Veterans Affairs Medical Center, Birmingham, Alabama 35233
| | - Stuart J Frank
- Department of Medicine (Y.L., Y.Z., J.J., S.J.F.), Division of Endocrinology, Diabetes, and Metabolism; Department of Radiology (K.R.Z.); and Department of Cell, Developmental, and Integrative Biology (S.J.F.), University of Alabama at Birmingham, Birmingham, Alabama 35294; Cancer Science Institute of Singapore and Department of Pharmacology (P.E.L.), National University of Singapore, Singapore 119077; Department of Radiology (R.P.), Stanford University School of Medicine, Palo Alto, California 94304; Department of Biological Sciences (J.F.L., W.Y.C.), Clemson University, Clemson, South Carolina 29634; and Endocrinology Section (S.J.F.), Medical Service, Veterans Affairs Medical Center, Birmingham, Alabama 35233
| |
Collapse
|
6
|
Gustbée E, Anesten C, Markkula A, Simonsson M, Rose C, Ingvar C, Jernström H. Excessive milk production during breast-feeding prior to breast cancer diagnosis is associated with increased risk for early events. SPRINGERPLUS 2013; 2:298. [PMID: 23853760 PMCID: PMC3706724 DOI: 10.1186/2193-1801-2-298] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 06/25/2013] [Indexed: 12/29/2022]
Abstract
Breast-feeding is a known protective factor against breast cancer. Breast-feeding duration is influenced by hormone levels, milk production, and lifestyle factors. The aims were to investigate how breast-feeding duration and milk production affected tumor characteristics and risk for early breast cancer events in primary breast cancer patients. Between 2002 and 2008, 634 breast cancer patients in Lund, Sweden, took part in an ongoing prospective cohort study. Data were extracted from questionnaires, pathology reports, and patients’ charts from 592 patients without preoperative treatment. Breast-feeding duration ≤12 months of the first child was associated with higher frequency of ER+/PgR+ tumors (P=0.02). Median follow-up time was 4.9 years. Higher risk for early events was observed for breast-feeding duration of first child >12 months (LogRank P=0.001), total breast-feeding duration >12 months (LogRank P=0.008), as well as ‘excessive milk production’ during breast-feeding of the first child (LogRank P=0.001). Patients with ‘almost no milk production’ had no events. In a multivariable model including both ‘excessive milk production’ and breast-feeding duration of the first child >12 months, both were associated with a two-fold risk for early events, adjusted HRs 2.33 (95% CI: 1.25-4.36) and 2.39 (0.97-5.85), respectively, while total breast-feeding duration was not. ‘Excessive milk production’ was associated with a two-fold risk of early distant metastases, adjusted HR 2.59 (1.13-5.94), but not duration. In conclusion, ‘excessive milk production’ during breast-feeding was associated with higher risk for early events independent of tumor characteristics, stressing the need to consider host factors in the evaluation of prognostic markers.
Collapse
Affiliation(s)
- Emma Gustbée
- Division of Oncology, Department of Clinical Sciences, Lund, Lund University, Barngatan 2B, Lund, SE-221 85 Sweden
| | | | | | | | | | | | | |
Collapse
|
7
|
Xu J, Sun D, Jiang J, Deng L, Zhang Y, Yu H, Bahl D, Langenheim JF, Chen WY, Fuchs SY, Frank SJ. The role of prolactin receptor in GH signaling in breast cancer cells. Mol Endocrinol 2012. [PMID: 23192981 DOI: 10.1210/me.2012-1297] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
GH and prolactin (PRL) are structurally related hormones that exert important effects in disparate target tissues. Their receptors (GHR and PRLR) reside in the cytokine receptor superfamily and share signaling pathways. In humans, GH binds both GHR and PRLR, whereas PRL binds only PRLR. Both hormones and their receptors may be relevant in certain human and rodent cancers, including breast cancer. GH and PRL promote signaling in human T47D breast cancer cells that express both GHR and PRLR. Furthermore, GHR and PRLR associate in a fashion augmented acutely by GH, even though GH primarily activates PRLR, rather than GHR, in these cells. To better understand PRLR's impact, we examined the effects of PRLR knockdown on GHR availability and GH sensitivity in T47D cells. T47D-ShPRLR cells, in which PRLR expression was reduced by stable short hairpin RNA (shRNA) expression, were compared with T47D-SCR control cells. PRLR knockdown decreased the rate of GHR proteolytic turnover, yielding GHR protein increase and ensuing sensitization of these cells to GHR signaling events including phosphorylation of GHR, Janus kinase 2, and signal transducer and activator of transcription 5 (STAT5). Unlike in T47D-SCR cells, acute GH signaling in T47D-ShPRLR cells was not blocked by the PRLR antagonist G129R but was inhibited by the GHR-specific antagonist, anti-GHR(ext-mAb). Thus, GH's use of GHR rather than PRLR was manifested when PRLR was reduced. In contrast to acute effects, GH incubation for 2 h or longer yielded diminished STAT5 phosphorylation in T47D-ShPRLR cells compared with T47D-SCR, a finding perhaps explained by markedly greater GH-induced GHR down-regulation in cells with diminished PRLR. However, when stimulated with repeated 1-h pulses of GH separated by 3-h washout periods to more faithfully mimic physiological GH pulsatility, T47D-ShPRLR cells exhibited greater transactivation of a STAT5-responsive luciferase reporter than did T47D-SCR cells. Our data suggest that PRLR's presence meaningfully affects GHR use in breast cancer cells.
Collapse
Affiliation(s)
- Jie Xu
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
8
|
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.
Collapse
Affiliation(s)
- E Michel
- Section of Small Animal Reproduction, Clinic of Reproductive Medicine, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | | | | | | | | |
Collapse
|
9
|
Langan EA, Griffiths CEM, Paus R. Utilizing the hair follicle to dissect the regulation and autocrine/paracrine activities of prolactin in humans. Am J Physiol Endocrinol Metab 2012; 302:E1311-2. [PMID: 22589417 DOI: 10.1152/ajpendo.00080.2012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
10
|
Harvey PW. Hypothesis: prolactin is tumorigenic to human breast: dispelling the myth that prolactin-induced mammary tumors are rodent-specific. J Appl Toxicol 2011; 32:1-9. [PMID: 22095846 DOI: 10.1002/jat.1772] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Revised: 10/14/2011] [Accepted: 10/14/2011] [Indexed: 11/09/2022]
Abstract
The commonly held assumption that rodent mammary tumors resulting from elevated prolactin are species-specific, or not biologically relevant to humans, is incorrect. Substantial epidemiological, clinical, and biological evidence now exists confirming the role of prolactin in human breast cancer. This evidence is evaluated and the argument presented that the tumorigenic risk from prolactin is therefore not species-specific to rodents but directly applies to humans. Further, as the mechanisms of prolactin-induced mammary tumor promotion and development appear analogous between rodents and humans, mammary tumorigenic findings in rodent carcinogenicity bioassays are both predictive and biologically relevant to the human response. Toxicologists and regulators need to consider this in carcinogenicity risk assessments.
Collapse
Affiliation(s)
- Philip W Harvey
- Covance Laboratories, Otley Road, Harrogate, North Yorkshire, HG3 1PY, UK.
| |
Collapse
|
11
|
Hargreaves A, Harleman J. Preclinical risk assessment of drug-induced hypo- and hyperprolactinemia. J Appl Toxicol 2011; 31:599-607. [DOI: 10.1002/jat.1723] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 07/08/2011] [Accepted: 07/08/2011] [Indexed: 11/08/2022]
Affiliation(s)
- Adam Hargreaves
- Pathology Department; Safety Assessment, Astrazeneca Pharmaceuticals; Alderley Park; Cheshire; SK10 4TG; UK
| | - Johannes Harleman
- Pathology Department; Safety Assessment, Astrazeneca Pharmaceuticals; Alderley Park; Cheshire; SK10 4TG; UK
| |
Collapse
|
12
|
Xu J, Zhang Y, Berry PA, Jiang J, Lobie PE, Langenheim JF, Chen WY, Frank SJ. Growth hormone signaling in human T47D breast cancer cells: potential role for a growth hormone receptor-prolactin receptor complex. Mol Endocrinol 2011; 25:597-610. [PMID: 21310852 DOI: 10.1210/me.2010-0255] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
GH receptor (GHR) and prolactin (PRL) receptor (PRLR) are structurally similar cytokine receptor superfamily members that are highly conserved among species. GH has growth-promoting and metabolic effects in various tissues in vertebrates, including humans. PRL is essential for regulation of lactation in mammals. Recent studies indicate that breast tissue bears GHR and PRLR and that both GH and PRL may impact development or behavior of breast cancer cells. An important facet of human GH (hGH) and human PRL (hPRL) biology is that although hPRL interacts only with hPRLR, hGH binds well to both hGHR and hPRLR. Presently, we investigated potential signaling effects of both hormones in the estrogen receptor- and progesterone receptor-positive human T47D breast cancer cell line. We found that this cell type expresses ample GHR and PRLR and responds well to both hGH and hPRL, as evidenced by activation of the Janus kinase 2/signal transducer and activator of transcription 5 pathway. Immunoprecipitation studies revealed specific GHR-PRLR association in these cells that was acutely enhanced by GH treatment. Although GH caused formation of disulfide-linked and chemically cross-linked GHR dimers in T47D cells, GH preferentially induced tyrosine phosphorylation of PRLR rather than GHR. Notably, both a GHR-specific ligand antagonist (B2036) and a GHR-specific antagonist monoclonal antibody (anti-GHR(ext-mAb)) failed to inhibit GH-induced signal transducer and activator of transcription 5 activation. In contrast, although the non-GHR-specific GH antagonist (G120R) and the PRL antagonist (G129R) individually only partially inhibited GH-induced activation, combined treatment with these two antagonists conferred greater inhibition than either alone. These data indicate that endogenous GHR and PRLR associate (possibly as a GHR-PRLR heterodimer) in human breast cancer cells and that GH signaling in these cells is largely mediated by the PRLR in the context of both PRLR-PRLR homodimers and GHR-PRLR heterodimers, broadening our understanding of how these related hormones and their related receptors may function in physiology and pathophysiology.
Collapse
Affiliation(s)
- Jie Xu
- Department of Medicine, University of Alabama at Birmingham, Alabama 35294-0012, USA
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Li X, Huang Y, Jiang J, Frank SJ. Synergy in ERK activation by cytokine receptors and tyrosine kinase growth factor receptors. Cell Signal 2010; 23:417-24. [PMID: 20946955 DOI: 10.1016/j.cellsig.2010.10.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Accepted: 10/01/2010] [Indexed: 10/19/2022]
Abstract
Epidermal growth factor (EGF) and platelet-derived growth factor (PDGF) signal through EGF and PDGF receptors, which are important receptor tyrosine kinases (RTKs). Growth hormone (GH) and prolactin (PRL) are four helical bundle peptide hormones that signal via GHR and PRLR, members of the cytokine receptor superfamily. In this study, we examine crosstalk between signaling pathways emanating from these disparate receptor groups (RTKs and cytokine receptors). We find that GH and EGF specifically synergize for activation of ERK in murine preadipocytes. The locus of this synergy resides at the level of MEK activation, but not above this level (i.e., not at the level of EGFR, SHC, or Raf activation). Furthermore, dephosphorylation of the scaffold protein, KSR, at a critical serine residue is also synergistically promoted by GH and EGF, suggesting that GH sensitizes these cells to EGF-induced ERK activation by augmenting the actions of KSR in facilitating MEK-ERK activation. Similarly specific synergy in ERK activation is also detected in human T47D breast cancer cells by cotreatment with PRL and PDGF. This synergy also resides at the level of MEK activation. Consistent with this synergy, PRL and PDGF also synergized for c-fos-dependent transactivation of a luciferase reporter gene in T47D cells, indicating that events downstream of ERK activation reflect this signaling synergy. Important conceptual and physiological implications of these findings are discussed.
Collapse
Affiliation(s)
- Xin Li
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, AL 35294-0012, USA
| | | | | | | |
Collapse
|
14
|
Carver KC, Arendt LM, Schuler LA. Complex prolactin crosstalk in breast cancer: new therapeutic implications. Mol Cell Endocrinol 2009; 307:1-7. [PMID: 19524120 PMCID: PMC3190192 DOI: 10.1016/j.mce.2009.03.014] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2009] [Accepted: 03/23/2009] [Indexed: 12/27/2022]
Abstract
The contributions of prolactin (PRL) to breast cancer are becoming increasingly recognized. To better understand the role for PRL in this disease, its interactions with other oncogenic growth factors and hormones must be characterized. Here, we review our current understanding of PRL crosstalk with other mammary oncogenic factors, including estrogen, epidermal growth factor (EGF) family members, and insulin-like growth factor-I (IGF-I). The ability of PRL to potentiate the actions of these targets of highly successful endocrine and molecular therapies suggests that PRL and/or its receptor (PRLR) may be an attractive therapeutic target(s). We discuss the potential benefit of PRL/PRLR-targeted therapy in combination with established therapies and implications for de novo and acquired resistance to treatment.
Collapse
Affiliation(s)
- Kristopher C. Carver
- Cellular and Molecular Biology Program, University of Wisconsin-Madison, Madison, WI 53706, United States
- Biotechnology Training Program, University of Wisconsin-Madison, Madison, WI 53706, United States
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI 53706, United States
| | - Lisa M. Arendt
- Cellular and Molecular Biology Program, University of Wisconsin-Madison, Madison, WI 53706, United States
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI 53706, United States
| | - Linda A. Schuler
- Cellular and Molecular Biology Program, University of Wisconsin-Madison, Madison, WI 53706, United States
- Biotechnology Training Program, University of Wisconsin-Madison, Madison, WI 53706, United States
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI 53706, United States
- Corresponding author at: Department of Comparative Biosciences, University of Wisconsin-Madison, 2015 Linden Drive, Madison, WI 53706, United States. Tel.: +1 608 263 9825; fax: +1 608 263 3926. (L.A. Schuler)
| |
Collapse
|
15
|
Tettamanzi MC, Keeler C, Meshack S, Hodsdon ME. Analysis of site-specific histidine protonation in human prolactin. Biochemistry 2008; 47:8638-47. [PMID: 18652486 DOI: 10.1021/bi800444t] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The structural and functional properties of human prolactin (hPRL), a 23 kDa protein hormone and cytokine, are pH-dependent. The dissociation rate constant for binding to the extracellular domain of the hPRL receptor increases nearly 500-fold over the relatively narrow and physiologic range from pH 8 to 6. As the apparent midpoint for this transition occurs around pH 6.5, we have looked toward histidine residues as a potential biophysical origin of the behavior. hPRL has a surprising number of nine histidines, nearly all of which are present on the protein surface. Using NMR spectroscopy, we have monitored site-specific proton binding to eight of these nine residues and derived equilibrium dissociation constants. During this analysis, a thermodynamic interaction between a localized triplet of three histidines (H27, H30, and H180) became apparent, which was subsequently confirmed by site-directed mutagenesis. After consideration of multiple potential models, we present statistical support for the existence of two negative cooperativity constants, one linking protonation of residues H30 and H180 with a magnitude of approximately 0.1 and the other weaker interaction between residues H27 and H30. Additionally, mutation of any of these three histidines to alanine stabilizes the folded protein relative to the chemically denatured state. A detailed understanding of these complex protonation reactions will aid in elucidating the biophysical mechanism of pH-dependent regulation of hPRL's structural and functional properties.
Collapse
Affiliation(s)
- M Cristina Tettamanzi
- Department of Laboratory Medicine, Yale University, New Haven, Connecticut 06520, USA
| | | | | | | |
Collapse
|
16
|
Frank SJ. Mechanistic aspects of crosstalk between GH and PRL and ErbB receptor family signaling. J Mammary Gland Biol Neoplasia 2008; 13:119-29. [PMID: 18236142 DOI: 10.1007/s10911-008-9065-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2007] [Accepted: 01/02/2008] [Indexed: 11/27/2022] Open
Abstract
Growth hormone (GH) and prolactin (PRL) are anterior pituitary hormones that have multiple roles in growth and metabolism. Both hormones are important in mammary development and breast cancer. The epidermal growth factor (EGF) family of peptides and the receptors that they activate (the ErbB family) are also major players in mammary biology and pathophysiology. Recent studies in signal transduction have highlighted the interplay between signaling pathways referred to as crosstalk. In this review, cell biological and signaling studies related to crosstalk between GH and PRL and the ErbB family are discussed. In particular, the role of GH- and PRL-induced phosphorylation of ErbB receptors in regulating EGF responsiveness is highlighted with attention to potential pathophysiological relevance.
Collapse
Affiliation(s)
- Stuart J Frank
- Department of Cell Biology and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, AL 35294-0012, USA.
| |
Collapse
|
17
|
Harvey PW, Everett DJ, Springall CJ. Adverse effects of prolactin in rodents and humans: breast and prostate cancer. J Psychopharmacol 2008; 22:20-7. [PMID: 18709700 DOI: 10.1177/0269881107082624] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Drugs and chemicals shown to induce mammary carcinogenesis in the rat/rodent via prolactin excess have traditionally been argued to pose little or no risk to humans in a regulatory toxicology context. The basis for this assumption is reviewed and placed into context with new evidence in humans that prolactin may be a tumour promoter in the breast and prostate. This evidence includes epidemiology, patient studies involving endocrine evaluation and molecular biology in human cells. It is concluded that hyperprolactinaemia is associated with an increase in breast cancer risk in both post and premenopausal women, that rat carcinogenicity studies are predictive of the human response, and that in a regulatory toxicology context prolactin-induced mammary tumours from nongenotoxic drugs and chemicals are an adverse effect that should not be ignored. More evidence is required concerning prostate cancer risk but molecular biology indicates that prolactin also induces prostate cell proliferation and inhibits apoptosis, which are similar to the responses observed in breast cancer cells.
Collapse
Affiliation(s)
- Philip W Harvey
- Department of Toxicology, Covance Laboratories Ltd., Otley Road, Harrogate, North Yorkshire, UK.
| | | | | |
Collapse
|
18
|
Harvey PW, Everett DJ, Springall CJ. Hyperprolactinaemia as an adverse effect in regulatory and clinical toxicology: role in breast and prostate cancer. Hum Exp Toxicol 2007; 25:395-404. [PMID: 16898168 DOI: 10.1191/0960327106ht643oa] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Historically, hyperprolactinaemia has been considered of low toxicological relevance when detected in toxicity studies, and even mammary carcinogenesis induced in the rat by prolactin excess has been considered of no relevance to humans. However, recent findings from human epidemiology and molecular biology suggests that prolactin is a risk factor for human breast cancer, and probably prostate cancer. Therefore, this new evidence should be considered in the various decisions to develop and license a new drug or chemical if the compound causes hyperprolactinaemia. This emerging evidence suggests that prolactin can also be produced locally from human breast cancer cells, and that, regardless of source (ie, pituitary or autocrine/paracrine production from cancer cells), prolactin is mitogenic, stimulates proliferation and suppresses apoptosis in breast and prostate cancer cells. This review outlines the evidence that hyperprolactinaemia should be considered a toxicological adverse effect and concludes that prolactin-induced rodent mammary carcinogenesis is relevant to humans and is not species-specific. The effects of prolactin on the prostate gland are also discussed; hyperprolactinaemia may be an additional risk factor for prostate cancer and this also requires consideration in toxicological risk assessments. The implications of increased prolactin secretion as an adverse effect for regulatory toxicology of drugs and chemicals, and in high risk patients receiving therapeutic drugs with hyperprolactinaemic side effects, is discussed. Alteration of prolactin level is also a novel mechanism that requires consideration in endocrine disruption research, since both endogenous oestrogens and also xenoestrogens stimulate prolactin secretion or affect prolactin receptors.
Collapse
Affiliation(s)
- P W Harvey
- Department of Toxicology, Covance Laboratories Ltd., Harrogate, North Yorkshire, UK.
| | | | | |
Collapse
|
19
|
Keeler C, Jablonski EM, Albert YB, Taylor BD, Myszka DG, Clevenger CV, Hodsdon ME. The kinetics of binding human prolactin, but not growth hormone, to the prolactin receptor vary over a physiologic pH range. Biochemistry 2007; 46:2398-410. [PMID: 17279774 DOI: 10.1021/bi061958v] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A member of the family of hematopoietic cytokines, human prolactin (hPRL) serves a dual role both as an endocrine hormone and as an autocrine/paracrine cytokine or growth factor. During investigation of the solution structural properties of hPRL, we have noted a surprising pH dependence of its structural stability over a range from approximately pH 6.0 to pH 8.0. An analysis of backbone atom NMR chemical shift changes and backbone amide hydrogen-deuterium exchange rates due to titration of the solution pH over this same range, along with calculations of protein surface electrostatic potential, suggests the possible involvement of a localized cluster of three His residues (27, 30, and 180), which comprise a portion of the high-affinity receptor-binding epitope. Surface plasmon resonance analysis of the interaction between hPRL and the extracellular domain (ECD) of the hPRL receptor reveals a selective 500-fold change in the dissociation rate between pH 8.3 and pH 5.8. In comparison, the interaction of hGH with the same receptor ECD did not demonstrate any significant dependence on pH. We also present an initial investigation of the pH dependence of hPRL function in rat Nb2 cell proliferation assays and a STAT5 luciferase gene reporter assay in the T47D human breast cancer cell line, whose results are consistent with our biophysical studies. The potential implications of this variation in hPRL's structural stability and receptor-binding kinetics over this physiologic range of pH are discussed.
Collapse
Affiliation(s)
- Camille Keeler
- Department of Laboratory Medicine, Yale University, New Haven, Connecticut 06520, USA
| | | | | | | | | | | | | |
Collapse
|
20
|
Miller SC, Bowman BM. Rapid inactivation and apoptosis of osteoclasts in the maternal skeleton during the bone remodeling reversal at the end of lactation. Anat Rec (Hoboken) 2007; 290:65-73. [PMID: 17441199 DOI: 10.1002/ar.20403] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
There is a rapid reversal in maternal skeletal metabolism and bone remodeling from accelerated bone resorption during lactation to skeletal rebuilding after lactation. The purpose was to determine the changes that occur in maternal osteoclasts during the transition from lactation to postlactation. Skeletal samples were taken from female rats on days 10 and 19 of lactation and 1 and 7 days after lactation. The pups were weaned on day 20. There was a rapid change in the osteoclast population after weaning, resulting in less resorption surface. Osteoclasts detached from bone surfaces, lost their ruffled borders, and became fragmented with immunocytochemical evidence of apoptosis within 24 hr after lactation. Concomitant with the rapid regression in the osteoclast population was an over fivefold increase in maternal calcitonin (CT) levels at 24 hr after weaning. Serum calcium and estrogen (E2) increased, but prolactin (PRL) and PTH decreased after weaning. The hormone changes, particularly that of CT, are consistent with the rapid regression of the osteoclast population at the end of lactation. These changes are similar to a reversal phase of a bone remodeling cycle where bone formation commences when resorption ceases on bone surfaces and suggests that the fate of osteoclasts during bone remodeling is programmed cell death. These results also suggest that bone remodeling is well synchronized prior to, during, and after lactation to accommodate the mineral requirements of the offspring as well as the mother.
Collapse
Affiliation(s)
- Scott C Miller
- Division of Radiobiology, Department of Radiology, School of Medicine, University of Utah, Salt Lake City, Utah 84108, USA.
| | | |
Collapse
|
21
|
Goffin V, Touraine P, Culler MD, Kelly PA. Drug Insight: prolactin-receptor antagonists, a novel approach to treatment of unresolved systemic and local hyperprolactinemia? ACTA ACUST UNITED AC 2006; 2:571-81. [PMID: 17024156 DOI: 10.1038/ncpendmet0270] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2005] [Accepted: 05/30/2006] [Indexed: 12/13/2022]
Abstract
Prolactin is a polypeptide hormone whose major biological actions are related to normal lactation and reproduction. Abnormally high prolactin levels, referred to as hyperprolactinemia, can result in various reproductive disorders. Currently, therapeutic management of hyperprolactinemia relies on dopamine agonists, since dopamine is the primary physiological suppressor of pituitary prolactin production. Epidemiologic studies have shown that prolactin levels in the high-normal range, as well as medications that interfere with dopamine action (e.g. certain antipsychotic drugs), might correlate with increased breast cancer risk. In addition to circulating prolactin, it is now well established that prolactin is also produced locally within various tissues, including breast and prostate. Increasing evidence, mainly from animal studies at present, suggests that excess locally produced prolactin may promote the growth of breast and prostate tumors via an autocrine or paracrine mechanism. These findings have renewed the interest in finding alternative strategies to suppress prolactin actions when dopamine agonists are ineffective. Our studies of the relationship between prolactin structure and function have resulted in the development of pure prolactin-receptor antagonists. These molecules prevent endogenous prolactin from exerting its actions via a competitive mechanism for receptor binding. In this review, we discuss the possible future therapeutic utility of this novel class of compounds.
Collapse
Affiliation(s)
- Vincent Goffin
- INSERM, Unit 808, Laboratory Faculté de Médecine Necker, 156 rue de Vaugirard, 75730, Paris Cedex 15, France.
| | | | | | | |
Collapse
|
22
|
Huang Y, Li X, Jiang J, Frank SJ. Prolactin modulates phosphorylation, signaling and trafficking of epidermal growth factor receptor in human T47D breast cancer cells. Oncogene 2006; 25:7565-76. [PMID: 16785991 DOI: 10.1038/sj.onc.1209740] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Prolactin (PRL) is a polypeptide hormone produced by the anterior pituitary gland and other sites that acts both systemically and locally to cause lactation and other biological effects by interacting with the PRL receptor, a Janus kinase (JAK)2-coupled cytokine receptor family member, and activating downstream signal pathways. Recent evidence suggests PRL is a player in the pathogenesis and progression of breast cancer. Epidermal growth factor (EGF) also has effects on breast tissue, working through its receptors, epidermal growth factor receptor (EGFR) and ErbB-2 (c-neu, HER2), both intrinsic tyrosine kinase growth factor receptors. EGFR promotes pubertal breast ductal morphogenesis in mice, and both EGFR and ErbB-2 are relevant in pathogenesis and behavior of breast and other human cancers. Previous studies showed that PRL and EGF synergize to enhance motility in the human breast cancer cell line, T47D. In this study, we explored crosstalk between the PRL and EGF signaling pathways in T47D cells, with an ultimate aim of understanding how these two important factors might work together in vivo to affect breast cancer behavior. Both PRL and EGF caused robust signaling in T47D cells; PRL acutely activated JAK2, signal transducer and activator of transcription-5 (STAT5), and extracellular signal-regulated kinase-1 and -2 (ERK1 and ERK2), whereas EGF caused EGFR activation and consequent src homology collagen (SHC) activation and ERK activation. Notably, PRL also caused phosphorylation of the EGFR and ErbB-2 at sites detected by PTP101, an antibody that recognizes threonine phosphorylation at consensus motifs for ERK-induced phosphorylation. PRL-induced PTP101-reactive phosphorylation was prevented by pretreatment with PD98059, an ERK pathway inhibitor. Furthermore, PRL synergized with EGF in activating SHC and ERK and transactivating a luciferase reporter driven by c-fos gene enhancer elements, suggesting that PRL allowed markedly enhanced EGF signaling. This was accompanied by substantial inhibition of EGF-induced EGFR downregulation when PRL and EGF cotreatment was compared to EGF treatment alone. This effect of PRL was abrogated by ERK pathway inhibitor pretreatment. Our data suggest that PRL synergistically augments EGF signaling in T47D breast cancer cells at least in part by lessening EGF-induced EGFR downregulation and that this effect requires PRL-induced ERK activity and threonine phosphorylation of EGFR.
Collapse
Affiliation(s)
- Y Huang
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, AL 35294-0012, USA
| | | | | | | |
Collapse
|
23
|
Albrektsen G, Heuch I, Thoresen S, Kvåle G. Clinical Stage of Breast Cancer by Parity, Age at Birth, and Time Since Birth: A Progressive Effect of Pregnancy Hormones? Cancer Epidemiol Biomarkers Prev 2006; 15:65-9. [PMID: 16434588 DOI: 10.1158/1055-9965.epi-05-0634] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Breast cancer diagnosed during pregnancy or 1 to 2 years after birth often occurs at a late stage. Little is known about tumor characteristics in the high-risk period shortly after a childbirth. We here explore whether stage of disease differs according to timing of births. Results are based on 22,351 Norwegian breast cancer patients of parity 0 to 5, ages 20 to 74 years. The proportion of stage II to IV tumors was considerably higher among parous than nulliparous women at age <30 years (52.7% versus 36.8%, P=0.009), but similar or lower in other age groups (P(interaction)=0.029). In general, the largest proportion of stage II to IV tumors was found among women diagnosed during pregnancy or <2 years after birth. However, among women with late-age births (first or second birth >or=30 years, third birth >or=35 years), as well as women with an early second birth (<25 years), the proportion with advanced disease was rather similar or even higher among those diagnosed 2 to 6 years after birth (49.3-56.0%). The association between clinical stage and time since birth reached statistical significance among women with a late first or second birth and among all triparous women (P <or= 0.032). The subgroups with a high proportion of advanced disease 2 to 6 years after birth corresponded quite well to those previously found to have the most pronounced transient increase in risk after birth. Thus, pregnancy hormones may have a progressive effect on breast cancer tumors in addition to a possible promoting effect. A potential effect of prolactin is discussed.
Collapse
Affiliation(s)
- Grethe Albrektsen
- Department of Mathematics, Center for International Health, University of Bergen, Bergen, Norway.
| | | | | | | |
Collapse
|
24
|
Courtillot C, Plu-Bureau G, Binart N, Balleyguier C, Sigal-Zafrani B, Goffin V, Kuttenn F, Kelly PA, Touraine P. Benign breast diseases. J Mammary Gland Biol Neoplasia 2005; 10:325-35. [PMID: 16900392 DOI: 10.1007/s10911-006-9006-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Benign breast diseases have always been neglected in comparison to cancer, despite the fact that there are many more patients with such diseases than patients presenting to a breast clinic for cancer. Like normal breast tissues, benign breast diseases are under a complex system of controls by both systemic hormonal and local factors. In this review, we attempt to present an overview of the latest knowledge concerning the epidemiology, classification, clinical presentation, management, and physiopathology of these disorders.
Collapse
Affiliation(s)
- Carine Courtillot
- Department of Endocrinology and Reproductive Medicine, Paris V University, GH Pitie-Salpetriere, 47/83 Bd de l'Hopital, AP-HP 75651, Paris Cedex 13, France
| | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Harvey PW. Human relevance of rodent prolactin-induced non-genotoxic mammary carcinogenesis: prolactin involvement in human breast cancer and significance for toxicology risk assessments. J Appl Toxicol 2005; 25:179-83. [PMID: 15856525 DOI: 10.1002/jat.1063] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Prolactin-induced mammary carcinogenesis in rodents, particularly rats, is often stated to be of low toxicological relevance to humans. This opinion appears to have developed from a number of lines of cited evidence. Firstly, there had been long experience of use of dopamine antagonists (that increase prolactin) in human medicine and no evidence of an increase in breast cancer incidence or risk had been reported. Secondly, dopamine agonists (that lower prolactin) had been shown to have no effect in human breast cancer treatment. Thirdly, the actions of prolactin were considered different between rodents and humans. However, recent evidence now suggests that prolactin has a major role in human breast cancer, and the similarity of mechanism with the rodent suggests that prolactin-mediated mammary carcinogenesis in rodents could be of much higher toxicological relevance to humans than previously thought. Large epidemiology studies have upgraded a limited database and shown that dopamine antagonists (both antipsychotics and anti-emetics) increase breast cancer risk, that hyperprolactinaemia is consistently associated with human breast cancer growth, development and poor prognosis, and that prolactin is indeed a mitogen in human breast cancer cells that suppresses apoptosis and upregulates BRCA1. It is now clear that initial studies giving dopamine agonists to breast cancer patients had no effect because breast cancer cells also produced prolactin independently of the pituitary, which remained uncontrolled and unrecognized in early clinical studies. The evidence for the role of prolactin in human breast cancer is now strong and consistent, and is discussed and related to the risk assessment of drugs and chemicals. The conclusion is that it is invalid to suggest that prolactin-induced mammary carcinogenesis in rodents is of low relevance to humans because prolactin can induce an adverse response in the mammary tissue of both rodents and humans alike. Drugs and chemicals causing rodent prolactin-induced mammary carcinogenesis may therefore pose a risk to humans via the same mechanism if exposures also increase prolactin secretion in humans.
Collapse
Affiliation(s)
- Philip W Harvey
- Department of Toxicology, Covance Laboratories, Otley Road, Harrogate, North Yorkshire HG3 1PY, UK.
| |
Collapse
|
26
|
Lu JC, Piazza TM, Schuler LA. Proteasomes mediate prolactin-induced receptor down-regulation and fragment generation in breast cancer cells. J Biol Chem 2005; 280:33909-16. [PMID: 16103113 PMCID: PMC1976473 DOI: 10.1074/jbc.m508118200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Prolactin regulates a variety of physiological processes, including mammary gland growth and differentiation, and recent findings support an important role in breast cancer development and progression. However, little is known about the trafficking of its receptor, a member of the cytokine receptor superfamily. In the present study, we examined the effect of ligand on the endogenous "long" isoform of the prolactin receptor in breast cancer cells. We found that prolactin caused rapid and prolonged down-regulation of this receptor. The prolactin-induced increase in degradation was blocked by inhibitors of both proteasomes and lysosomes. However, the ubiquitin-conjugating system was not required for internalization. Prolactin also resulted in the concomitant appearance of a cell-associated prolactin receptor fragment containing the extracellular domain. This latter process required proteasomal, but not metalloprotease, activity, distinguishing it from ectodomain "shedding" of other membrane receptors, which are secreted as binding proteins. The prolactin receptor fragment was labeled by surface biotinylation and independent of protein synthesis. Together, these data indicated that prolactin binding initiates limited proteasomal cleavage of its receptor, generating a cell-associated fragment containing the extracellular domain. Our findings described a new potential mediator of prolactin action and a novel mechanism whereby proteasomes modulate cellular processes.
Collapse
Affiliation(s)
- Juu-Chin Lu
- From the Department of Comparative Biosciences
- Endocrinology-Reproductive Physiology Program, and
| | - Timothy M. Piazza
- From the Department of Comparative Biosciences
- Comparative Biomedical Sciences Program, University of Wisconsin-Madison, Wisconsin 53706
| | - Linda A. Schuler
- From the Department of Comparative Biosciences
- Endocrinology-Reproductive Physiology Program, and
- Comparative Biomedical Sciences Program, University of Wisconsin-Madison, Wisconsin 53706
- To whom correspondence should be addressed: Dept. of Comparative Biosciences, University of Wisconsin, 2015 Linden Dr., Madison, WI 53706. Tel.: 608-263-9825; Fax: 608-263-3926; E-mail:
| |
Collapse
|
27
|
Goffin V, Bernichtein S, Touraine P, Kelly PA. Development and potential clinical uses of human prolactin receptor antagonists. Endocr Rev 2005; 26:400-22. [PMID: 15814850 DOI: 10.1210/er.2004-0016] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
There is a large body of literature showing that prolactin (PRL) exerts growth-promoting activities in breast cancer, and possibly in prostate cancer and prostate hyperplasia. In addition, increasing evidence argues for the involvement of locally produced (autocrine) PRL, perhaps even more than pituitary-secreted (endocrine) PRL, in tumor growth. Because dopamine analogs are unable to inhibit PRL production in extrapituitary sites, alternative strategies need investigation. To that end, several PRL receptor antagonists have been developed by introducing various mutations into its natural ligands. For all but one of these analogs, the mechanism of action involves a competition with endogenous PRL for receptor binding. Such compounds are thus candidates to counteract the undesired actions of PRL, not only in tumors, but also in dopamine-resistant prolactinomas. In this review, we describe the different versions of antagonists that have been developed, with emphasis on the controversies regarding their characterization, and the limits for their potential development as a drug. The most recently developed antagonist, Delta1-9-G129R-hPRL, is the only one that is totally devoid of residual agonistic activity, meaning it acts as pure antagonist. We discuss to what extent this new molecule could be considered as a lead compound for inhibiting the actions of human PRL in the above-mentioned diseases. We also speculate on the multiple questions that could be addressed with respect to the therapeutic use of PRL receptor antagonists in patients.
Collapse
Affiliation(s)
- Vincent Goffin
- Institut National de la Santé et de la Recherche Médicale Unit 584, Faculté de Médecine Necker, 156, rue de Vaugirard, 75730 Paris Cedex 15, France.
| | | | | | | |
Collapse
|
28
|
GUTZMAN JENNIFERH, RUGOWSKI DEBRAE, SCHROEDER MATTHEWD, WATTERS JYOTIJ, SCHULER LINDAA. Multiple kinase cascades mediate prolactin signals to activating protein-1 in breast cancer cells. Mol Endocrinol 2004; 18:3064-75. [PMID: 15319452 PMCID: PMC1634796 DOI: 10.1210/me.2004-0187] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The importance of prolactin (PRL) in physiological proliferation and differentiation of the mammary gland, together with high levels of PRL receptors in breast tumors, the association of circulating PRL with incidence of breast cancer, and the recognition of locally produced PRL, point to the need for greater understanding of PRL actions in mammary disease. Although PRL has been shown to activate multiple kinase cascades in various target cells, relatively little is known of its signaling pathways in the mammary gland apart from the Janus kinase 2/ signal transducer and activator of transcription 5 pathway, particularly in tumor cells. Another potential effector is activating protein-1 (AP-1), a transcription complex that regulates processes essential for neoplastic progression, including proliferation, survival and invasion. We demonstrate that PRL activates AP-1 in MCF-7 cells, detectable at 4 h and sustained for at least 24 h. Although Janus kinase 2 and ERK1/2 are the primary mediators of PRL-induced signals, c-Src, phosphatidylinositol 3'-kinase, protein kinase C, and other MAPKs contribute to maximal activity. PRL activation of these pathways leads to increased c-Jun protein and phosphorylation, JunB protein, and phosphorylation of c-Fos, elevating the levels of AP-1 complexes able to bind DNA. These active AP-1 dimers may direct expression of multiple target genes, mediating some of PRL's actions in mammary disease.
Collapse
Affiliation(s)
| | | | | | | | - LINDA A. SCHULER
- Address all correspondence and requests for reprints to: L. A. Schuler, Department of Comparative Biosciences, University of Wisconsin, 2015 Linden Drive, Madison, Wisconsin 53706. E-mail:
| |
Collapse
|
29
|
Sancak B, Coskun U, Gunel N, Onuk E, Cihan A, Karamercan A, Yildirim Y, Ozkan S. No association between serum levels of insulin-like growth factor-I, vascular endothelial growth factor, prolactin and clinicopathological characteristics of breast carcinoma after surgery. Intern Med J 2004; 34:310-5. [PMID: 15228391 DOI: 10.1111/j.1444-0903.2004.00591.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Angiogenesis is essential for tumour growth and metastasis. Vascular endothelial growth factor (VEGF) has been suggested as the major angio-genic factor in breast carcinoma. Both insulin-like growth factor-I (IGF-I) and prolactin are involved in the progression of breast cancer at least partly by stimulating angiogenesis. AIM The aim of the present study was to investigate the association between serum IGF-I, VEGF and prolactin levels and clinicopathological characteristics of breast carcinoma. METHODS Serum IGF-I, VEGF and prolactin levels were measured in breast cancer patients and controls and these levels were compared with well-known clinicopathological characteristics of breast carcinoma, including tumour size, axillary lymph node and oestrogen/progesterone receptor status, tumour grade and disease stage. RESULTS Serum prolactin, VEGF and IGF-I levels were found to be similar in breast cancer patients and control subjects (P > 0.05). When the patients were divided into groups according to their tumour size, axillary lymph node status, tumour grade, oestrogen/progesterone receptor status and disease stage, no significant differences in serum prolactin, VEGF and IGF-I levels were found among the groups (P > 0.05). CONCLUSIONS The present study failed to demonstrate an association between serum levels of VEGF, IGF-I and prolactin and well-known clinicopathological characteristics of breast carcinoma.
Collapse
Affiliation(s)
- B Sancak
- Department of Biochemistry, Gazi University Medical School, Ankara, Turkey
| | | | | | | | | | | | | | | |
Collapse
|
30
|
Schroeder MD, Brockman JL, Walker AM, Schuler LA. Inhibition of prolactin (PRL)-induced proliferative signals in breast cancer cells by a molecular mimic of phosphorylated PRL, S179D-PRL. Endocrinology 2003; 144:5300-7. [PMID: 12970160 DOI: 10.1210/en.2003-0826] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Posttranslational modifications of prolactin (PRL), including phosphorylation, vary with physiologic state and alter biologic activity. In light of the growing evidence for a role for PRL in proliferation in mammary cancer, we examined the ability of a mimic of phosphorylated human PRL, S179D-PRL, to initiate signals to several pathways in mammary tumor cells alone and in combination with unmodified PRL. Unmodified PRL employed multiple pathways to increase cellular proliferation and cyclin D1 levels in PRL-deficient MCF-7 cells. S179D-PRL was a weak agonist compared with unmodified PRL with regard to cellular proliferation, cyclin D1 levels, and phosphorylation of signal transducer and activator of transcription 5 and ERKs. However, S179D-PRL was a potent antagonist of unmodified PRL to these endpoints. In contrast to the reduced levels of the long isoform of the PRL receptor observed in response to a 3-d incubation with unmodified PRL, S179D-PRL up-regulated expression of this isoform, 4-fold. These studies support the utility of this mutant as a PRL antagonist to proliferative signals in mammary epithelial cells, including a potential role in breast cancer therapeutics.
Collapse
Affiliation(s)
- Matthew D Schroeder
- Department of Comparative Biosciences, University of Wisconsin, Madison, Wisconsin 53706, USA.
| | | | | | | |
Collapse
|
31
|
Rose-Hellekant TA, Arendt LM, Schroeder MD, Gilchrist K, Sandgren EP, Schuler LA. Prolactin induces ERalpha-positive and ERalpha-negative mammary cancer in transgenic mice. Oncogene 2003; 22:4664-74. [PMID: 12879011 PMCID: PMC1630768 DOI: 10.1038/sj.onc.1206619] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The role of prolactin in human breast cancer has been controversial. However, it is now apparent that human mammary epithelial cells can synthesize prolactin endogenously, permitting autocrine/paracrine actions within the mammary gland that are independent of pituitary prolactin. To model this local mammary production of prolactin (PRL), we have generated mice that overexpress prolactin within mammary epithelial cells under the control of a hormonally nonresponsive promoter, neu-related lipocalin (NRL). In each of the two examined NRL-PRL transgenic mouse lineages, female virgin mice display mammary developmental abnormalities, mammary intraepithelial neoplasias, and invasive neoplasms. Prolactin increases proliferation in morphologically normal alveoli and ducts, as well as in lesions. The tumors are of varied histotype, but papillary adenocarcinomas and adenosquamous neoplasms predominate. Neoplasms can be separated into two populations: one is estrogen receptor alpha (ERalpha) positive (greater than 15% of the cells stain for ERalpha), and the other is ERalpha- (<3%). ERalpha expression does not correlate with tumor histotype, or proliferative or apoptotic indices. These studies provide a mouse model of hormonally dependent breast cancer, and, perhaps most strikingly, a model in which some neoplasms retain ERalpha, as occurs in the human disease.
Collapse
Affiliation(s)
- Teresa A Rose-Hellekant
- Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin, 2015 Linden Dr., Madison, WI 53706, USA
| | - Lisa M Arendt
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, 2015 Linden Dr., Madison, WI 53706, USA
| | - Matthew D Schroeder
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, 2015 Linden Dr., Madison, WI 53706, USA
| | - Kennedy Gilchrist
- Department of Pathology and Laboratory Medicine, School of Medicine, University of Wisconsin, Madison, WI 53706, USA
| | - Eric P Sandgren
- Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin, 2015 Linden Dr., Madison, WI 53706, USA
| | - Linda A Schuler
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, 2015 Linden Dr., Madison, WI 53706, USA
- *Correspondence: LA Schuler; E-mail:
| |
Collapse
|
32
|
Comings DE, Gade-Andavolu R, Cone LA, Muhleman D, MacMurray JP. A multigene test for the risk of sporadic breast carcinoma. Cancer 2003; 97:2160-70. [PMID: 12712467 DOI: 10.1002/cncr.11340] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
BACKGROUND Although the identification of the BRCA1 and BRCA2 genes have been of great interest, these genes account for less than 5% of all breast carcinoma cases. The remaining cases are sporadic. Reanalysis of a large twin study suggested that genetic factors may play a significant role in sporadic breast and other carcinomas. Sporadic breast carcinoma is polygenically inherited. Multiple genes are likely to have an additive effect, each gene accounting for a fraction of the variance. One factor that may have an impact on the development of hormonally responsive breast tumors is the duration of exposure of the breast to estrogen. Therefore, one of the demographic risk factors for breast carcinoma is an early age of onset of menarche. The current study was based on the hypothesis that genes that play a role in demographic risk factors may be breast carcinoma risk genes in their own right. The authors hypothesized that six genes relevant to the timing of the onset of menarche and related risk factors might be candidate genes for breast carcinoma. These were the leptin gene (LEP), the leptin receptor gene (LEPR), the catechol-0-methyltransferase gene (COMT), the dopamine D(2) receptor gene (DRD2), the estrogen 1 receptor gene (ESR1), and the androgen receptor gene (AR). METHODS The authors examined 67 women with postmenopausal sporadic breast carcinoma and 145 gender and race-matched controls. RESULTS Five of these genes accounted for a significant percent of the variance (r(2)) of breast carcinoma. The following r(2) and P values were calculated: LEP: 0.073, P < or = 0.0001; LEPR: 0.064, P < or = 0.0002; COMT: 0.073, P < or = 0.0001; AR: 0.040, P < or = 0.0035; and DRD2: 0.018, P < or = 0.05. When evaluated in a multivariate regression analysis, they accounted collectively for 24% of the variance of breast carcinoma (P < or = 0.0001). These genes accounted for 40% of the variance (P < or = 0.00001) in a subset of age-matched cases. Individual gene scores were added to form a breast carcinoma risk score (BCRS) that ranged from 0 to 17. When the BCRS was evaluated in a receiver operator characteristic plot, the area under the curve was 0.80 for the full set and 0.869 for the age-matched set. The relative breast carcinoma risk for the different BCRS scores ranged from 0.10 to 11.9. CONCLUSIONS These results demonstrate a potentially powerful method of evaluating the additive effect of multiple breast carcinoma risk genes to form a potentially clinically useful assessment of women's risk for sporadic breast carcinoma.
Collapse
Affiliation(s)
- David E Comings
- Department of Medical Genetics, City of Hope Medical Center, Duarte, California 91010, USA.
| | | | | | | | | |
Collapse
|
33
|
|
34
|
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.
Collapse
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
Collapse
Affiliation(s)
- Charles V Clevenger
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
| | | | | | | |
Collapse
|
35
|
Barresi V, Condorelli DF, Fortuna CG, Musumarra G, Scirè S. In vitro antitumor activities of 2,6-di-[2-(heteroaryl)vinyl]pyridines and pyridiniums. Bioorg Med Chem 2002; 10:2899-904. [PMID: 12110310 DOI: 10.1016/s0968-0896(02)00142-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The in vitro antitumor activities of 2,6-di-[2-(heteroaryl)vinyl]pyridines versus the standard National Cancer Institute 60 cell lines panel and of 2,6-di-[2-(heteroaryl)vinyl] pyridinium cations versus MCF7 (human mammary carcinoma) and LNCap (prostate carcinoma) cell lines are reported. Antiproliferative effects in both series are particularly evident for MCF7 mammary adenocarcinoma cells. Multivariate analysis of DNA microarray data for responsive tumor cell lines suggest a mechanistic pathway involving polyamine biosynthesis and prolactin signal transduction.
Collapse
Affiliation(s)
- Vincenza Barresi
- Dipartimento Scienze Chimiche, Università di Catania, V.le A.Doria 6, 95125 Catania, Italy
| | | | | | | | | |
Collapse
|
36
|
Abstract
Prolactin (PRL) is a paradoxical hormone. Historically known as the pituitary hormone of lactation, it has had attributed to it more than 300 separate actions, which can be correlated to the quasi-ubiquitous distribution of its receptor. Meanwhile, PRL-related knockout models have mainly highlighted its irreplaceable role in functions of lactation and reproduction, which suggests that most of its other reported target tissues are presumably modulated by, rather than strictly dependent on, PRL. The multiplicity of PRL actions in animals is in direct opposition to the paucity of arguments that suggest its involvement in human pathophysiology other than effects on reproduction. Although many experimental data argue for a role of PRL in the progression of some tumors, such as breast and prostate cancers, drugs lowering circulating PRL levels are ineffective. This observation opens new avenues for research into the understanding of whether local production of PRL is involved in tumor growth and, if so, how extrapituitary PRL synthesis is regulated. Finally, the physiological relevance of PRL variants, such as the antiangiogenic 16K-like PRL fragments, needs to be elucidated. This review is aimed at critically discussing how these recent findings have renewed the manner in which PRL should be considered as a multifunctional hormone.
Collapse
Affiliation(s)
- Vincent Goffin
- INSERM Unit 344, Faculty of Medicine Necker, Paris Cedex 15, 75730, France.
| | | | | | | |
Collapse
|
37
|
Imagawa W, Pedchenko VK, Helber J, Zhang H. Hormone/growth factor interactions mediating epithelial/stromal communication in mammary gland development and carcinogenesis. J Steroid Biochem Mol Biol 2002; 80:213-30. [PMID: 11897505 DOI: 10.1016/s0960-0760(01)00188-1] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Epithelial/mesenchymal interactions begin during embryonic development of the mammary gland and continue throughout mammary gland development into adult life. Stromal and epithelial growth factors that may mediate interactions between these compartments of the mammary gland are reviewed. Since mammogenic hormones are the primary regulators of mammary gland development, special consideration is given to hormonal regulation of growth factors in order to explore the integration of hormones and growth factors in the regulation of mammary gland growth and neoplasia. Examination of hormonal regulation of the fibroblast growth factor (FGF)-7/FGFR2-IIIb receptor system in the mammary gland reveals that mammogenic hormones differentially regulate the synthesis of stromal growth factors and their epithelial receptors. These effects serve to optimize the action of estrogen and progesterone on mammary gland development and illustrate that the ratio of these two hormones is critical in regulating this growth factor axis. The role of stromal/epithelial mitogenic microenvironments in modulating the genotype and phenotype of preneoplastic and neoplastic lesions by chemical carcinogens is discussed. Finally, changes in growth factor expression during mammary tumor progression are described to illustrate the relative roles that stromally-derived and epithelial-derived growth factors may play during progression to hormone independent tumor growth.
Collapse
Affiliation(s)
- Walter Imagawa
- Department of Molecular and Integrative Physiology, Kansas Cancer Institute, University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS 66160-7417, USA.
| | | | | | | |
Collapse
|
38
|
Schroeder MD, Symowicz J, Schuler LA. PRL modulates cell cycle regulators in mammary tumor epithelial cells. Mol Endocrinol 2002; 16:45-57. [PMID: 11773438 DOI: 10.1210/mend.16.1.0762] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
PRL is essential for normal lobulo-alveolar growth of the mammary gland and may contribute to mammary cancer development or progression. However, analysis of the mechanism of action of PRL in these processes is complicated by the production of PRL within mammary epithelia. To examine PRL actions in a mammary cell-specific context, we selected MCF-7 cells that lacked endogenous PRL synthesis, using PRL stimulation of interferon-gamma-activated sequence-related PRL response elements. Derived clones exhibited a greater proliferative response to PRL than control cells. To understand the mechanism, we examined, by Western analysis, levels of proteins essential for cell cycle progression as well as phosphorylation of retinoblastoma protein. The expression of cyclin D1, a critical regulator of the G1/S transition, was significantly increased by PRL and was associated with hyperphosphorylation of retinoblastoma protein at Ser(780). Cyclin B1 was also increased by PRL. In contrast, PRL decreased the Cip/Kip family inhibitor, p21, but not p16 or p27. These studies demonstrate that PRL can stimulate the cell cycle in mammary epithelia and identify specific targets in this process. This model system will enable further molecular dissection of the pathways involved in PRL-induced proliferation, increasing our understanding of this hormone and its interactions with other factors in normal and pathogenic processes.
Collapse
Affiliation(s)
- Matthew D Schroeder
- Department of Comparative Biosciences, University of Wisconsin, Madison, Wisconsin 53706, USA
| | | | | |
Collapse
|
39
|
Bernichtein S, Kinet S, Jeay S, Llovera M, Madern D, Martial JA, Kelly PA, Goffin V. S179D-human PRL, a pseudophosphorylated human PRL analog, is an agonist and not an antagonist. Endocrinology 2001; 142:3950-63. [PMID: 11517174 DOI: 10.1210/endo.142.9.8369] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
For many years, our group has been involved in the development of human PRL antagonists. In two recent publications, S179D-human PRL, a human PRL analog designed to mimic a putative S179-phosphorylated human PRL, was reported to be a highly potent antagonist of human PRL-induced proliferation and signaling in rat Nb2 cells. We prepared this analog with the aim of testing it in various bioassays involving the homologous, human PRL receptor. In our hands, S179D- human PRL was able to stimulate 1) the proliferation of rat Nb2 cells and of human mammary tumor epithelial cells (T-47D), 2) transcriptional activation of the lactogenic hormone response element-luciferase reporter gene, and 3) activation of the Janus kinase/signal transducer and activator of transcription and MAPK pathways. Using the previously characterized antagonist G129R-human PRL as a control, we failed to observe any evidence for antagonism of S179D-human PRL toward any of the human PRL-induced effects analyzed, including cell proliferation, transcriptional activation, and signaling. In conclusion, our data argue that S179D-human PRL is an agonist displaying slightly reduced affinity and activity due to local alteration of receptor binding site 1, and that the antagonistic properties previously attributed to S179D-human PRL cannot be confirmed in any of the assays analyzed in this study.
Collapse
Affiliation(s)
- S Bernichtein
- INSERM, U-344, Molecular Endocrinology, Faculté de Médecine Necker, 75730 Paris, France
| | | | | | | | | | | | | | | |
Collapse
|
40
|
Glasow A, Horn LC, Taymans SE, Stratakis CA, Kelly PA, Kohler U, Gillespie J, Vonderhaar BK, Bornstein SR. Mutational analysis of the PRL receptor gene in human breast tumors with differential PRL receptor protein expression. J Clin Endocrinol Metab 2001; 86:3826-32. [PMID: 11502819 DOI: 10.1210/jcem.86.8.7753] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
PRL is a major growth and differentiating hormone in the human breast, with activation of the PRL-PRL receptor complex increasingly recognized as an important mechanism in the induction and progression of mammary tumors. Although constitutive activation of various hormone and growth factor receptors is newly recognized as a common cause of tumor development, the PRL receptor gene has not been analyzed for similar aberrations in breast and other tumors. Therefore, using bacterial artificial chromosomes containing the PRL receptor gene and intron-spanning PCR, we determined the exon-surrounding intron sequences providing primers for the first analysis of the entire coding region of the human PRL receptor gene. We examined the presence of PRL receptor in 41 breast tumors by immunohistochemistry and attempted a correlation of its expression to pathological grading of the disease. Then tumor cells were isolated by laser capture microdissection to examine DNA from 30 patients for PRL receptor mutations. The PRL receptor immunoreactive score did not correlate to the tumor size, histopathological grading, age, or family history of patients. PRL receptor immunoreactivity was predominantly found in steroid hormone receptor-positive tumors, but without overall correlation of immunoreactive score. In both PRL receptor-positive and PRL receptor- negative breast cancer cells, direct sequencing of the coding sequence of the PRL receptor gene did not detect any somatic or hereditary gene aberrations. In conclusion, PRL receptor mutations do not appear to be common in human breast cancer, suggesting that constitutive activation of the PRL receptor can be excluded as a major cause of mammary tumor genesis. The molecular structure of the PRL receptor seems to remain intact in tumor tissue, and systemic and local production of PRL may participate in tumor cell growth and proliferation through functional receptors.
Collapse
MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Breast Neoplasms/genetics
- Breast Neoplasms/pathology
- Carcinoma, Ductal, Breast/genetics
- Carcinoma, Ductal, Breast/pathology
- Carcinoma, Lobular/genetics
- Carcinoma, Lobular/pathology
- DNA Mutational Analysis
- DNA Primers
- DNA, Neoplasm/genetics
- Exons
- Female
- Humans
- Immunohistochemistry
- Introns
- Middle Aged
- Neoplasm Invasiveness
- Neoplasm Staging
- Polymerase Chain Reaction
- Receptors, Estrogen/analysis
- Receptors, Progesterone/analysis
- Receptors, Prolactin/analysis
- Receptors, Prolactin/genetics
Collapse
Affiliation(s)
- A Glasow
- Children's Hospital, University of Leipzig, 04317 Leipzig, Germany.
| | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Abstract
The mammary gland life cycle is exemplified by massive, physiologically dictated changes in cell number and composition, architecture, and functionality. These drastic upheavals, by necessity, also involve the mammary endothelium, which undergoes angiogenic expansion during pregnancy and lactation followed by ordered regression during involution. In this review, we summarise data obtained using the Mercox methyl methacrylate corrosion cast technique to analyse the mammary gland vasculature during normal development and carcinogenesis. Concomitant with epithelial cell expansion, the mammary vasculature grows during the first half of pregnancy by sprouting angiogenesis whereas the last half of pregnancy and lactation are characterised by the non-proliferative intussusceptive angiogenesis. The vasculature of the lactating gland is composed of a well-developed capillary meshwork enveloping the secretory alveoli with basket-like honeycomb structures. During involution, regression of the vasculature is achieved by regional collapse of the honeycomb structures, capillary retraction, and endothelial attenuation. This process appears partly to involve apoptosis. However, an additional mechanism involving remodelling without cell death, which we have termed angiomeiosis, must exist to explain the morphological observations. Interestingly, in mammary tumours of neuT transgenic mice, both sprouting and intussusceptive angiogenesis was observed simultaneously in the same nodules, a finding with potential implications for cancer therapy. The underlying molecular mechanisms controlling angiogenic modulation in the mammary gland, particularly angiogenic regression and the endothelial:parenchymal interplay, are poorly understood. However, the data summarised in this review indicate that precisely these molecular mechanisms offer novel alternatives for specific and effective treatment of breast cancer.
Collapse
Affiliation(s)
- V Djonov
- Institute of Anatomy, University of Berne, CH-3011 Berne, Switzerland
| | | | | |
Collapse
|
42
|
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: 1503] [Impact Index Per Article: 62.6] [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.
Collapse
Affiliation(s)
- M E Freeman
- Department of Biological Science, Florida State University, Tallahassee, Florida 32306-4340, USA.
| | | | | | | |
Collapse
|
43
|
Llovera M, Pichard C, Bernichtein S, Jeay S, Touraine P, Kelly PA, Goffin V. Human prolactin (hPRL) antagonists inhibit hPRL-activated signaling pathways involved in breast cancer cell proliferation. Oncogene 2000; 19:4695-705. [PMID: 11032019 DOI: 10.1038/sj.onc.1203846] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The involvement of human prolactin (hPRL) in breast cancer has been recently reconsidered based on its autocrine/paracrine proliferative effect described in human mammary tumor epithelial cells. Therefore, there is growing interest in the development of potent hPRL antagonists that may inhibit this effect. We previously designed hPRL analogs displaying antagonistic properties in a human transcriptional bioassay. We now report that the most potent of those analogs, G129R-hPRL, antagonizes all hPRL-induced effects analysed in various breast cancer cell lines, including cell proliferation. The analog per se lacks intrinsic agonistic activity on PRL receptor-activated signaling cascades, cell proliferation and apoptosis, indicating that its mode of action only occurs through competitive inhibition of hPRL. We provide some molecular basis of this antagonistic effect by demonstrating that G129R-hPRL competitively inhibits hPRL-activation of the JAK-STAT and MAPK pathways, two signaling cascades involved in the mitogenic effect of hPRL in mammary epithelial cells. This competitive inhibition persists for at least 48 h, as evidenced by long term analysis of STAT5b activation or of progression through cell cycle. These results are the first demonstration at the molecular level that hPRL antagonists interfering with receptor dimerization disrupt signaling events in breast cancer cells, which prevents hPRL-induced cell proliferation.
Collapse
Affiliation(s)
- M Llovera
- INSERM Unit 344, Molecular Endocrinology, Faculté de Médecine Necker, Paris, France
| | | | | | | | | | | | | |
Collapse
|
44
|
Llovera M, Touraine P, Kelly PA, Goffin V. Involvement of prolactin in breast cancer: redefining the molecular targets. Exp Gerontol 2000; 35:41-51. [PMID: 10705038 DOI: 10.1016/s0531-5565(99)00078-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The mammary gland is the major target tissue of prolactin (PRL) in mammals. Although this pituitary hormone has been long suspected to be involved in the progression of human breast cancer, the failure of clinical improvement by treatment with dopamine agonists (which lower circulating levels of PRL) rapidly reduced the interest of oncologists concerning a potential role of PRL in the development of breast cancer. Within the last few years, however, several studies reported first, that PRL is also synthesized by mammary epithelial cells, and second that it may exert a proliferative action in an autocrine/paracrine manner. In agreement with a recent epidemiological study, these observations have led to a reconsideration of the role of PRL as an active participant in breast cancer, and are an impetus to redefine the molecular targets of anti-prolactin strategies since dopamine analogs are assumed to be inefficient on extrapituitary PRL synthesis. In this review, we briefly summarize the current knowledge of PRL effects on both normal and tumor mammary cells, and we discuss the most relevant articles supporting the autocrine-paracrine action of PRL in the breast. With the aim of defining putative new molecular targets, we propose an overview of the main PRL receptor signaling cascades known to be triggered by PRL in mammary epithelial cells or, when not available, in other cell types. Finally, because proteolytic fragments of rat PRL have been shown to inhibit the angiogenic process, which may be relevant for preventing the progression of solid tumors such as breast tumors, we discuss the hypothesis that the enzymatic cleavage of human PRL could also represent a new molecular target in the search for alternative strategies in the treatment of breast cancer.
Collapse
Affiliation(s)
- M Llovera
- INSERM Unit 344-Molecular Endocrinology, Faculté de Médecine Necker, 156 rue de Vaugirard, 75730, Paris, France
| | | | | | | |
Collapse
|