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Wu AML, Gossa S, Samala R, Chung MA, Gril B, Yang HH, Thorsheim HR, Tran AD, Wei D, Taner E, Isanogle K, Yang Y, Dolan EL, Robinson C, Difilippantonio S, Lee MP, Khan I, Smith QR, McGavern DB, Wakefield LM, Steeg PS. Aging and CNS Myeloid Cell Depletion Attenuate Breast Cancer Brain Metastasis. Clin Cancer Res 2021; 27:4422-4434. [PMID: 34083229 PMCID: PMC9974011 DOI: 10.1158/1078-0432.ccr-21-1549] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 05/17/2021] [Accepted: 05/21/2021] [Indexed: 11/16/2022]
Abstract
PURPOSE Breast cancer diagnosed in young patients is often aggressive. Because primary breast tumors from young and older patients have similar mutational patterns, we hypothesized that the young host microenvironment promotes more aggressive metastatic disease. EXPERIMENTAL DESIGN Triple-negative or luminal B breast cancer cell lines were injected into young and older mice side-by-side to quantify lung, liver, and brain metastases. Young and older mouse brains, metastatic and naïve, were analyzed by flow cytometry. Immune populations were depleted using antibodies or a colony-stimulating factor-1 receptor (CSF-1R) inhibitor, and brain metastasis assays were conducted. Effects on myeloid populations, astrogliosis, and the neuroinflammatory response were determined. RESULTS Brain metastases were 2- to 4-fold higher in young as compared with older mouse hosts in four models of triple-negative or luminal B breast cancer; no age effect was observed on liver or lung metastases. Aged brains, naïve or metastatic, contained fewer resident CNS myeloid cells. Use of a CSF-1R inhibitor to deplete myeloid cells, including both microglia and infiltrating macrophages, preferentially reduced brain metastasis burden in young mice. Downstream effects of CSF-1R inhibition in young mice resembled that of an aged brain in terms of myeloid numbers, induction of astrogliosis, and Semaphorin 3A secretion within the neuroinflammatory response. CONCLUSIONS Host microenvironmental factors contribute to the aggressiveness of triple-negative and luminal B breast cancer brain metastasis. CSF-1R inhibitors may hold promise for young brain metastasis patients.
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Affiliation(s)
- Alex Man Lai Wu
- Women’s Malignancies Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Selamawit Gossa
- Viral Immunology and Intravital Imaging Section, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland
| | - Ramakrishna Samala
- School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, Texas
| | - Monika A. Chung
- Women’s Malignancies Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Brunilde Gril
- Women’s Malignancies Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Howard H. Yang
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Helen R. Thorsheim
- School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, Texas
| | - Andy D. Tran
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland.,CCR Microscopy Core, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Debbie Wei
- Women’s Malignancies Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Esra Taner
- Women’s Malignancies Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Kristine Isanogle
- Laboratory Animal Sciences Program, Frederick National Laboratory for Cancer Research, National Cancer Institute, Frederick, Maryland
| | - Yuan Yang
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Emma L. Dolan
- Women’s Malignancies Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Christina Robinson
- Laboratory Animal Sciences Program, Frederick National Laboratory for Cancer Research, National Cancer Institute, Frederick, Maryland
| | - Simone Difilippantonio
- Laboratory Animal Sciences Program, Frederick National Laboratory for Cancer Research, National Cancer Institute, Frederick, Maryland
| | - Maxwell P. Lee
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Imran Khan
- Women’s Malignancies Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Quentin R. Smith
- School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, Texas
| | - Dorian B. McGavern
- Viral Immunology and Intravital Imaging Section, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland
| | - Lalage M. Wakefield
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Patricia S. Steeg
- Women’s Malignancies Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
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Lai Wu AM, Gossa S, Samala R, Chung M, Gril B, Yang H, Thorsheim H, Tran A, Wei D, Isanogle K, Yang Y, Dolan E, Robinson C, Difilippantonio S, Lee M, Smith Q, McGavern D, Wakefield L, Steeg P. 29. ROLE OF AGE AND CNS MYELOID CELLS ON BREAST CANCER BRAIN METASTASIS. Neurooncol Adv 2020. [PMCID: PMC7401405 DOI: 10.1093/noajnl/vdaa073.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Women diagnosed with breast cancer at a younger age (typically defined as < 40 years old) often have a poorer prognosis and an increased risk of brain metastasis compared to their older counterparts. Multivariate analyses accounting for differences in tumor characteristics have shown that age is an independent predictor of worse outcome. We therefore hypothesized that rather than intrinsic tumor properties, extrinsic microenvironmental factors contribute to age-related differences in aggressiveness. The effect of age was examined by injecting brain-selected breast cancer cells into young (2 – 6 months) and older (>12 months) mice. In four brain metastasis models examined, young mice developed 2- to 16-fold (p < 0.05) more brain metastases compared to older mice. The effect of age was not observed in mouse breast cancer models that metastasize to liver and lungs, suggesting that this is an organ-specific phenomenon. Flow cytometry-based immune-profiling of mouse brains showed that T-cells (CD4+, CD8+, and FOXP3+CD25+ regulatory T-cells), monocytes and neutrophils were elevated in brains with metastases, but the abundance of these populations did not vary dramatically with age. Furthermore, antibody-based depletion of T-cells, monocytes and neutrophils did not significantly alter brain metastasis development. Microglia, which are resident CNS myeloid cells, were 1.5-fold more abundant in young brains compared to older brains. Depletion of CNS myeloid cells using the colony stimulating factor-1-receptor inhibitor PLX3397 reduced brain metastatic tumor burden in young mice by 2.1-fold (p < 0.001). Importantly, loss of CNS myeloid cells/microglia, which are normally more activated in aged mice and thus may protect the older brain against metastasis, did not augment brain metastasis formation in older mice. These results suggest that the younger brain is more permissive for breast cancer metastasis and that targeting resident CNS myeloid cells may be an effective strategy to prevent brain metastasis development in younger patients.
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Affiliation(s)
| | - Selamawit Gossa
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | | | | | | | | | - Helen Thorsheim
- Texas Tech University Health Sciences Center, Amarillo, TX, USA
| | - Andy Tran
- National Cancer Institute, Bethesda/MD, USA
| | - Debbie Wei
- National Cancer Institute, Bethesda/MD, USA
| | | | - Yuan Yang
- National Cancer Institute, Bethesda/MD, USA
| | - Emma Dolan
- National Cancer Institute, Bethesda/MD, USA
| | | | | | | | - Quentin Smith
- Texas Tech University Health Sciences Center, Amarillo, TX, USA
| | - Dorian McGavern
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
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Yang Y, Yang HH, Tang B, Wu AML, Flanders KC, Moshkovich N, Weinberg DS, Welsh MA, Weng J, Ochoa HJ, Hu TY, Herrmann MA, Chen J, Edmondson EF, Simpson RM, Liu F, Liu H, Lee MP, Wakefield LM. The Outcome of TGFβ Antagonism in Metastatic Breast Cancer Models In Vivo Reflects a Complex Balance between Tumor-Suppressive and Proprogression Activities of TGFβ. Clin Cancer Res 2019; 26:643-656. [PMID: 31582516 DOI: 10.1158/1078-0432.ccr-19-2370] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 08/28/2019] [Accepted: 09/30/2019] [Indexed: 12/28/2022]
Abstract
PURPOSE TGFβs are overexpressed in many advanced cancers and promote cancer progression through mechanisms that include suppression of immunosurveillance. Multiple strategies to antagonize the TGFβ pathway are in early-phase oncology trials. However, TGFβs also have tumor-suppressive activities early in tumorigenesis, and the extent to which these might be retained in advanced disease has not been fully explored. EXPERIMENTAL DESIGN A panel of 12 immunocompetent mouse allograft models of metastatic breast cancer was tested for the effect of neutralizing anti-TGFβ antibodies on lung metastatic burden. Extensive correlative biology analyses were performed to assess potential predictive biomarkers and probe underlying mechanisms. RESULTS Heterogeneous responses to anti-TGFβ treatment were observed, with 5 of 12 models (42%) showing suppression of metastasis, 4 of 12 (33%) showing no response, and 3 of 12 (25%) showing an undesirable stimulation (up to 9-fold) of metastasis. Inhibition of metastasis was immune-dependent, whereas stimulation of metastasis was immune-independent and targeted the tumor cell compartment, potentially affecting the cancer stem cell. Thus, the integrated outcome of TGFβ antagonism depends on a complex balance between enhancing effective antitumor immunity and disrupting persistent tumor-suppressive effects of TGFβ on the tumor cell. Applying transcriptomic signatures derived from treatment-naïve mouse primary tumors to human breast cancer datasets suggested that patients with breast cancer with high-grade, estrogen receptor-negative disease are most likely to benefit from anti-TGFβ therapy. CONCLUSIONS Contrary to dogma, tumor-suppressive responses to TGFβ are retained in some advanced metastatic tumors. Safe deployment of TGFβ antagonists in the clinic will require good predictive biomarkers.
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Affiliation(s)
- Yuan Yang
- Lab of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Howard H Yang
- Lab of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Binwu Tang
- Lab of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Alex Man Lai Wu
- Lab of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Kathleen C Flanders
- Lab of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Nellie Moshkovich
- Lab of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Douglas S Weinberg
- Lab of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Michael A Welsh
- Lab of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Jia Weng
- Lab of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Humberto J Ochoa
- Lab of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Tiffany Y Hu
- Collaborative Protein Technology Resource, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Michelle A Herrmann
- Collaborative Protein Technology Resource, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Jinqiu Chen
- Collaborative Protein Technology Resource, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Elijah F Edmondson
- Pathology Histotechnology Laboratory, Frederick National Laboratory for Cancer Research, Frederick, Maryland
| | - R Mark Simpson
- Lab of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Fang Liu
- Center for Advanced Biotechnology and Medicine, Susan Lehman Cullman Laboratory for Cancer Research, Department of Chemical Biology, Ernest Mario School of Pharmacy, Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, Piscataway, New Jersey
| | - Huaitian Liu
- Lab of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Maxwell P Lee
- Lab of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Lalage M Wakefield
- Lab of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland.
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Lai Wu AM, Dolan E, Gril B, Robinson C, Difilippantonio S, Wakefield L, Steeg P. TMIC-37. THE MICROENVIRONMENT OF A YOUNGER BRAIN IS MORE PERMISSIVE FOR BREAST CANCER BRAIN METASTASIS. Neuro Oncol 2017. [DOI: 10.1093/neuonc/nox168.1025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Wu AML, Dedina L, Dalvi P, Yang M, Leon-Cheon J, Earl B, Harper PA, Ito S. Riboflavin uptake transporter Slc52a2 (RFVT2) is upregulated in the mouse mammary gland during lactation. Am J Physiol Regul Integr Comp Physiol 2016; 310:R578-85. [PMID: 26791833 DOI: 10.1152/ajpregu.00507.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 01/16/2016] [Indexed: 12/13/2022]
Abstract
While it is well recognized that riboflavin accumulates in breast milk as an essential vitamin for neonates, transport mechanisms for its milk excretion are not well characterized. The multidrug efflux transporter ABCG2 in the apical membrane of milk-producing mammary epithelial cells (MECs) is involved with riboflavin excretion. However, it is not clear whether MECs possess other riboflavin transport systems, which may facilitate its basolateral uptake into MECs. We report here that transcripts encoding the second (SLC52A2) and third (SLC52A3) member of the recently discovered family of SLC52A riboflavin uptake transporters are expressed in milk fat globules from human breast milk. Furthermore, Slc52a2 and Slc52a3 mRNA are upregulated in the mouse mammary gland during lactation. Importantly, the induction ofSlc52a2, which was the major Slc52a riboflavin transporter in the lactating mammary gland, was also observed at the protein level. Subcellular localization studies showed that green fluorescent protein-tagged mouse SLC52A2 mainly localized to the cell membrane, with no preferential distribution to the apical or basolateral membrane in polarized kidney MDCK cells. These results strongly implicate a potential role for SLC52A2 in riboflavin uptake by milk-producing MECs, a critical step in the transfer of riboflavin into breast milk.
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Affiliation(s)
- Alex Man Lai Wu
- Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; and Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada; and
| | - Liana Dedina
- Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; and Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada; and
| | - Pooja Dalvi
- Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; and
| | - Mingdong Yang
- Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; and
| | - John Leon-Cheon
- Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; and Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada; and
| | - Brian Earl
- Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; and
| | - Patricia A Harper
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada; and
| | - Shinya Ito
- Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; and Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada; and Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada
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Wu AML, Yang M, Dalvi P, Turinsky AL, Wang W, Butcher D, Egan SE, Weksberg R, Harper PA, Ito S. Role of STAT5 and epigenetics in lactation-associated upregulation of multidrug transporter ABCG2 in the mammary gland. Am J Physiol Endocrinol Metab 2014; 307:E596-610. [PMID: 25117410 DOI: 10.1152/ajpendo.00323.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The multidrug resistance efflux transporter ATP-binding cassette subfamily G member 2 (ABCG2) is not only overexpressed in certain drug-resistant cancers but is also highly expressed in the mammary gland during lactation, carrying xenobiotics and nutrients into milk. We sought to investigate the molecular mechanisms involved in the upregulation of ABCG2 during lactation. Expression profiling of different mouse Abcg2 mRNA isoforms (E1a, E1b, and E1c) revealed that E1b is predominantly expressed and induced in the lactating mouse mammary gland. Despite this induction, analyses of CpG methylation status and published ChIP-seq datasets reveal that E1b promoter sequences in the virgin gland are already hypomethylated and marked with the open chromatin histone mark H3K4me2. Using a forced-weaning model to shut down lactation, we found that within 24 h there was a significant reduction in Abcg2 mRNA expression and a loss of signal transducer and activator of transcription-5 (STAT5) occupancy at the mouse Abcg2 gene. Luciferase reporter assays further showed that some of these STAT5-binding regions that contained interferon-γ-activated sequence (GAS) motifs function as an enhancer after prolactin treatment. We conclude that Abcg2 is already poised for expression in the virgin mammary gland and that STAT5 plays an important role in Abcg2 expression during lactation.
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Affiliation(s)
- Alex Man Lai Wu
- Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
| | - Mingdong Yang
- Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Pooja Dalvi
- Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Andrei L Turinsky
- Centre for Computational Medicine, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Wei Wang
- Developmental and Stem Cell Biology Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Darci Butcher
- Genetics and Genome Biology Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Sean E Egan
- Developmental and Stem Cell Biology Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Rosanna Weksberg
- Genetics and Genome Biology Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada; and Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Patricia A Harper
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
| | - Shinya Ito
- Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada; Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada; and
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Wu AML, Dalvi P, Lu X, Yang M, Riddick DS, Matthews J, Clevenger CV, Ross DD, Harper PA, Ito S. Induction of multidrug resistance transporter ABCG2 by prolactin in human breast cancer cells. Mol Pharmacol 2012; 83:377-88. [PMID: 23150485 DOI: 10.1124/mol.112.082362] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The multidrug transporter, breast cancer resistance protein, ABCG2, is up-regulated in certain chemoresistant cancer cells and in the mammary gland during lactation. We investigated the role of the lactogenic hormone prolactin (PRL) in the regulation of ABCG2. PRL dose-dependently induced ABCG2 expression in T-47D human breast cancer cells. This induction was significantly reduced by short-interfering RNA-mediated knockdown of Janus kinase 2 (JAK2). Knockdown or pharmacologic inhibition of the down-stream signal transducer and activator of transcription-5 (STAT5) also blunted the induction of ABCG2 by PRL, suggesting a role for the JAK2/STAT5 pathway in PRL-induced ABCG2 expression. Corroborating these findings, we observed PRL-stimulated STAT5 recruitment to a region containing a putative γ-interferon activation sequence (GAS) element at -434 base pairs upstream of the ABCG2 transcription start site. Introduction of a single mutation to the -434 GAS element significantly attenuated PRL-stimulated activity of a luciferase reporter driven by the ABCG2 gene promoter and 5'-flanking region containing the -434 GAS motif. In addition, this GAS element showed strong copy number dependency in its response to PRL treatment. Interestingly, inhibitors against the mitogen-activated protein kinase and phosphoinositide-3-kinase signaling pathways significantly decreased the induction of ABCG2 by PRL without altering STAT5 recruitment to the GAS element. We conclude that the JAK2/STAT5 pathway is required but not sufficient for the induction of ABCG2 by PRL.
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Affiliation(s)
- Alex Man Lai Wu
- Program in Physiology and Experimental Medicine, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
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