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Pihlajamaa P, Kauko O, Sahu B, Kivioja T, Taipale J. A competitive precision CRISPR method to identify the fitness effects of transcription factor binding sites. Nat Biotechnol 2023; 41:197-203. [PMID: 36163549 PMCID: PMC9931575 DOI: 10.1038/s41587-022-01444-6] [Citation(s) in RCA: 1] [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] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 07/20/2022] [Indexed: 12/26/2022]
Abstract
Here we describe a competitive genome editing method that measures the effect of mutations on molecular functions, based on precision CRISPR editing using template libraries with either the original or altered sequence, and a sequence tag, enabling direct comparison between original and mutated cells. Using the example of the MYC oncogene, we identify important transcriptional targets and show that E-box mutations at MYC target gene promoters reduce cellular fitness.
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Affiliation(s)
- Päivi Pihlajamaa
- Applied Tumor Genomics Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Otto Kauko
- Applied Tumor Genomics Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Department of Biochemistry, University of Cambridge, Cambridge, UK
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku, Finland
| | - Biswajyoti Sahu
- Applied Tumor Genomics Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Medicum, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Teemu Kivioja
- Applied Tumor Genomics Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Jussi Taipale
- Applied Tumor Genomics Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
- Department of Biochemistry, University of Cambridge, Cambridge, UK.
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden.
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Aavikko M, Kaasinen E, Andersson N, Pentinmikko N, Sulo P, Donner I, Pihlajamaa P, Kuosmanen A, Bramante S, Katainen R, Sipilä LJ, Martin S, Arola J, Carpén O, Heiskanen I, Mecklin JP, Taipale J, Ristimäki A, Lehti K, Gucciardo E, Katajisto P, Schalin-Jäntti C, Vahteristo P, Aaltonen LA. WNT2 activation through proximal germline deletion predisposes to small intestinal neuroendocrine tumors and intestinal adenocarcinomas. Hum Mol Genet 2021; 30:2429-2440. [PMID: 34274970 PMCID: PMC8643507 DOI: 10.1093/hmg/ddab206] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 07/13/2021] [Accepted: 07/14/2021] [Indexed: 12/13/2022] Open
Abstract
Many hereditary cancer syndromes are associated with an increased risk of small and large intestinal adenocarcinomas. However, conditions bearing a high risk to both adenocarcinomas and neuroendocrine tumors are yet to be described. We studied a family with 16 individuals in four generations affected by a wide spectrum of intestinal tumors, including hyperplastic polyps, adenomas, small intestinal neuroendocrine tumors, and colorectal and small intestinal adenocarcinomas. To assess the genetic susceptibility and understand the novel phenotype, we utilized multiple molecular methods, including whole genome sequencing, RNA sequencing, single cell sequencing, RNA in situ hybridization and organoid culture. We detected a heterozygous deletion at the cystic fibrosis locus (7q31.2) perfectly segregating with the intestinal tumor predisposition in the family. The deletion removes a topologically associating domain border between CFTR and WNT2, aberrantly activating WNT2 in the intestinal epithelium. These consequences suggest that the deletion predisposes to small intestinal neuroendocrine tumors and small and large intestinal adenocarcinomas, and reveals the broad tumorigenic effects of aberrant WNT activation in the human intestine.
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Affiliation(s)
- Mervi Aavikko
- Department of Medical and Clinical Genetics, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
- Applied Tumor Genomics Research Program, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
- Institute for Molecular Medicine Finland (FIMM), Helsinki Institute of Life Sciences (HiLIFE), University of Helsinki, FI-00014 Helsinki, Finland
| | - Eevi Kaasinen
- Department of Medical and Clinical Genetics, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
- Applied Tumor Genomics Research Program, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
| | - Noora Andersson
- Department of Pathology, Medicum, University of Helsinki, FI-00014 Helsinki, Finland
| | - Nalle Pentinmikko
- Institute of Biotechnology, Helsinki Institute of Life Sciences (HiLIFE), University of Helsinki, FI-00014 Helsinki, Finland
| | - Päivi Sulo
- Department of Medical and Clinical Genetics, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
- Applied Tumor Genomics Research Program, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
| | - Iikki Donner
- Department of Medical and Clinical Genetics, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
- Applied Tumor Genomics Research Program, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
| | - Päivi Pihlajamaa
- Applied Tumor Genomics Research Program, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
| | - Anna Kuosmanen
- Department of Medical and Clinical Genetics, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
- Applied Tumor Genomics Research Program, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
| | - Simona Bramante
- Department of Medical and Clinical Genetics, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
- Applied Tumor Genomics Research Program, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
| | - Riku Katainen
- Department of Medical and Clinical Genetics, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
- Applied Tumor Genomics Research Program, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
| | - Lauri J Sipilä
- Department of Medical and Clinical Genetics, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
- Applied Tumor Genomics Research Program, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
| | - Samantha Martin
- Department of Medical and Clinical Genetics, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
- Applied Tumor Genomics Research Program, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
| | - Johanna Arola
- Department of Pathology, HUSLAB, HUS Diagnostic Center, Helsinki University Hospital and University of Helsinki, 00290 Helsinki, Finland
| | - Olli Carpén
- Department of Pathology, HUSLAB, HUS Diagnostic Center, Helsinki University Hospital and University of Helsinki, 00290 Helsinki, Finland
- Research Program in Systems Oncology, University of Helsinki, FI-00014 Helsinki, Finland
| | - Ilkka Heiskanen
- Endocrine Surgery, Abdominal Center, University of Helsinki and Helsinki University Hospital, 00290 Helsinki, Finland
| | - Jukka-Pekka Mecklin
- Department of Surgery, Central Finland Central Hospital, 40620 Jyväskylä, Finland
- Faculty of Sport and Health Sciences, University of Jyväskylä, FI-40014 Jyväskylä, Finland
| | - Jussi Taipale
- Applied Tumor Genomics Research Program, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
| | - Ari Ristimäki
- Applied Tumor Genomics Research Program, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
- Department of Pathology, HUSLAB, HUS Diagnostic Center, Helsinki University Hospital and University of Helsinki, 00290 Helsinki, Finland
| | - Kaisa Lehti
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 171 77 Stockholm, Sweden
- Individualized Drug Therapy Research Program, Faculty of Medicine, University of Helsinki, 00014 Helsinki, Finland
| | - Erika Gucciardo
- Individualized Drug Therapy Research Program, Faculty of Medicine, University of Helsinki, 00014 Helsinki, Finland
| | - Pekka Katajisto
- Institute of Biotechnology, Helsinki Institute of Life Sciences (HiLIFE), University of Helsinki, FI-00014 Helsinki, Finland
- Department of Biosciences and Nutrition, Karolinska Institutet, 141 83 Huddinge, Sweden
- Faculty of Biological and Environmental Sciences, University of Helsinki, FI-00014 Helsinki, Finland
- Department of Cell and Molecular Biology, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Camilla Schalin-Jäntti
- Endocrinology, Abdominal Center, University of Helsinki and Helsinki University Hospital, 00290 Helsinki, Finland
| | - Pia Vahteristo
- Department of Medical and Clinical Genetics, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
- Applied Tumor Genomics Research Program, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
| | - Lauri A Aaltonen
- Department of Medical and Clinical Genetics, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
- Applied Tumor Genomics Research Program, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
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Sahu B, Pihlajamaa P, Zhang K, Palin K, Ahonen S, Cervera A, Ristimäki A, Aaltonen LA, Hautaniemi S, Taipale J. Human cell transformation by combined lineage conversion and oncogene expression. Oncogene 2021; 40:5533-5547. [PMID: 34302118 PMCID: PMC8429043 DOI: 10.1038/s41388-021-01940-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 06/17/2021] [Accepted: 07/01/2021] [Indexed: 02/07/2023]
Abstract
Cancer is the most complex genetic disease known, with mutations implicated in more than 250 genes. However, it is still elusive which specific mutations found in human patients lead to tumorigenesis. Here we show that a combination of oncogenes that is characteristic of liver cancer (CTNNB1, TERT, MYC) induces senescence in human fibroblasts and primary hepatocytes. However, reprogramming fibroblasts to a liver progenitor fate, induced hepatocytes (iHeps), makes them sensitive to transformation by the same oncogenes. The transformed iHeps are highly proliferative, tumorigenic in nude mice, and bear gene expression signatures of liver cancer. These results show that tumorigenesis is triggered by a combination of three elements: the set of driver mutations, the cellular lineage, and the state of differentiation of the cells along the lineage. Our results provide direct support for the role of cell identity as a key determinant in transformation and establish a paradigm for studying the dynamic role of oncogenic drivers in human tumorigenesis.
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Affiliation(s)
- Biswajyoti Sahu
- Applied Tumor Genomics Research Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Medicum, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Department of Biochemistry, University of Cambridge, Cambridge, UK
- iCAN Digital Precision Cancer Medicine Flagship, Helsinki, Finland
| | - Päivi Pihlajamaa
- Applied Tumor Genomics Research Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Kaiyang Zhang
- Research Program in Systems Oncology, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Kimmo Palin
- Applied Tumor Genomics Research Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- iCAN Digital Precision Cancer Medicine Flagship, Helsinki, Finland
- Department of Medical and Clinical Genetics, University of Helsinki, Helsinki, Finland
| | - Saija Ahonen
- Applied Tumor Genomics Research Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Alejandra Cervera
- Research Program in Systems Oncology, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Instituto Nacional de Medicina Genómica, Mexico City, Mexico, Finland
| | - Ari Ristimäki
- Applied Tumor Genomics Research Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Medicum, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Department of Pathology, HUSLAB and HUS Diagnostic Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Lauri A Aaltonen
- Applied Tumor Genomics Research Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- iCAN Digital Precision Cancer Medicine Flagship, Helsinki, Finland
- Department of Medical and Clinical Genetics, University of Helsinki, Helsinki, Finland
| | - Sampsa Hautaniemi
- Research Program in Systems Oncology, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Jussi Taipale
- Applied Tumor Genomics Research Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
- Department of Biochemistry, University of Cambridge, Cambridge, UK.
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
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Abstract
The physiological androgens testosterone and 5α-dihydrotestosterone regulate the development and maintenance of primary and secondary male sexual characteristics through binding to the androgen receptor (AR), a ligand-dependent transcription factor. In addition, a number of nonreproductive tissues of both genders are subject to androgen regulation. AR is also a central target in the treatment of prostate cancer. A large number of studies over the last decade have characterized many regulatory aspects of the AR pathway, such as androgen-dependent transcription programs, AR cistromes, and coregulatory proteins, mostly in cultured cells of prostate cancer origin. Moreover, recent work has revealed the presence of pioneer/licensing factors and chromatin modifications that are important to guide receptor recruitment onto appropriate chromatin loci in cell lines and in tissues under physiological conditions. Despite these advances, current knowledge related to the mechanisms responsible for receptor- and tissue-specific actions of androgens is still relatively limited. Here, we review topics that pertain to these specificity issues at different levels, both in cultured cells and tissues in vivo, with a particular emphasis on the nature of the steroid, the response element sequence, the AR cistromes, pioneer/licensing factors, and coregulatory proteins. We conclude that liganded AR and its DNA-response elements are required but are not sufficient for establishment of tissue-specific transcription programs in vivo, and that AR-selective actions over other steroid receptors rely on relaxed rather than increased stringency of cis-elements on chromatin.
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Affiliation(s)
- Päivi Pihlajamaa
- Department of Physiology (P.P., B.S., O.A.J.), and Research Programs Unit, Genome-Scale Biology (P.P., B.S.), Biomedicum Helsinki, University of Helsinki, FI-00014 Helsinki, Finland
| | - Biswajyoti Sahu
- Department of Physiology (P.P., B.S., O.A.J.), and Research Programs Unit, Genome-Scale Biology (P.P., B.S.), Biomedicum Helsinki, University of Helsinki, FI-00014 Helsinki, Finland
| | - Olli A Jänne
- Department of Physiology (P.P., B.S., O.A.J.), and Research Programs Unit, Genome-Scale Biology (P.P., B.S.), Biomedicum Helsinki, University of Helsinki, FI-00014 Helsinki, Finland
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Heinonen H, Lepikhova T, Sahu B, Pehkonen H, Pihlajamaa P, Louhimo R, Gao P, Wei GH, Hautaniemi S, Jänne OA, Monni O. Identification of several potential chromatin binding sites of HOXB7 and its downstream target genes in breast cancer. Int J Cancer 2015; 137:2374-83. [PMID: 26014856 PMCID: PMC4744995 DOI: 10.1002/ijc.29616] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 05/11/2015] [Indexed: 12/13/2022]
Abstract
HOXB7 encodes a transcription factor that is overexpressed in a number of cancers and encompasses many oncogenic functions. Previous results have shown it to promote cell proliferation, angiogenesis, epithelial–mesenchymal transition, DNA repair and cell survival. Because of its role in many cancers and tumorigenic processes, HOXB7 has been suggested to be a potential drug target. However, HOXB7 binding sites on chromatin and its targets are poorly known. The aim of our study was to identify HOXB7 binding sites on breast cancer cell chromatin and to delineate direct target genes located nearby these binding sites. We found 1,504 HOXB7 chromatin binding sites in BT‐474 breast cancer cell line that overexpresses HOXB7. Seventeen selected binding sites were validated by ChIP‐qPCR in several breast cancer cell lines. Furthermore, we analyzed expression of a large number of genes located nearby HOXB7 binding sites and found several new direct targets, such as CTNND2 and SCGB1D2. Identification of HOXB7 chromatin binding sites and target genes is essential to understand better the role of HOXB7 in breast cancer and mechanisms by which it regulates tumorigenic processes. What's new? The transcription factor HOXB7 is overexpressed in various cancers, but it's not yet known just which genes HOXB7 activates. How does it influence cancer on a molecular level? This study found 1500 sequences where HOXB7 binds the chromatin in breast cancer cells. They went on to identify several potential target genes near the HOXB7 binding sites. Not only will finding these genes help explain how HOXB7 overexpression promotes tumor growth, it will help understand what side effects might result from hindering HOXB7 expression.
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Affiliation(s)
- Henna Heinonen
- Research Programs' Unit, Genome-Scale Biology and Institute of Biomedicine, Medical Biochemistry and Developmental Biology, University of Helsinki, Helsinki, Finland
| | - Tatiana Lepikhova
- Research Programs' Unit, Genome-Scale Biology and Institute of Biomedicine, Medical Biochemistry and Developmental Biology, University of Helsinki, Helsinki, Finland
| | - Biswajyoti Sahu
- Institute of Biomedicine/Physiology, University of Helsinki, Helsinki, Finland
| | - Henna Pehkonen
- Research Programs' Unit, Genome-Scale Biology and Institute of Biomedicine, Medical Biochemistry and Developmental Biology, University of Helsinki, Helsinki, Finland
| | - Päivi Pihlajamaa
- Institute of Biomedicine/Physiology, University of Helsinki, Helsinki, Finland
| | - Riku Louhimo
- Research Programs' Unit, Genome-Scale Biology and Institute of Biomedicine, Medical Biochemistry and Developmental Biology, University of Helsinki, Helsinki, Finland
| | - Ping Gao
- Biocenter Oulu and Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Gong-Hong Wei
- Biocenter Oulu and Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Sampsa Hautaniemi
- Research Programs' Unit, Genome-Scale Biology and Institute of Biomedicine, Medical Biochemistry and Developmental Biology, University of Helsinki, Helsinki, Finland
| | - Olli A Jänne
- Institute of Biomedicine/Physiology, University of Helsinki, Helsinki, Finland
| | - Outi Monni
- Research Programs' Unit, Genome-Scale Biology and Institute of Biomedicine, Medical Biochemistry and Developmental Biology, University of Helsinki, Helsinki, Finland
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Sahu B, Pihlajamaa P, Dubois V, Kerkhofs S, Claessens F, Jänne OA. Androgen receptor uses relaxed response element stringency for selective chromatin binding and transcriptional regulation in vivo. Nucleic Acids Res 2014; 42:4230-40. [PMID: 24459135 PMCID: PMC3985627 DOI: 10.1093/nar/gkt1401] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The DNA-binding domains (DBDs) of class I steroid receptors—androgen, glucocorticoid, progesterone and mineralocorticoid receptors—recognize a similar cis-element, an inverted repeat of 5′-AGAACA-3′ with a 3-nt spacer. However, these receptors regulate transcription programs that are largely receptor-specific. To address the role of the DBD in and of itself in ensuring specificity of androgen receptor (AR) binding to chromatin in vivo, we used SPARKI knock-in mice whose AR DBD has the second zinc finger replaced by that of the glucocorticoid receptor. Comparison of AR-binding events in epididymides and prostates of wild-type (wt) and SPARKI mice revealed that AR achieves selective chromatin binding through a less stringent sequence requirement for the 3′-hexamer. In particular, a T at position 12 in the second hexamer is dispensable for wt AR but mandatory for SPARKI AR binding, and only a G at position 11 is highly conserved among wt AR-preferred response elements. Genome-wide AR-binding events agree with the respective transcriptome profiles, in that attenuated AR binding in SPARKI mouse epididymis correlates with blunted androgen response in vivo. Collectively, AR-selective actions in vivo rely on relaxed rather than increased stringency of cis-elements on chromatin. These elements are, in turn, poorly recognized by other class I steroid receptors.
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Affiliation(s)
- Biswajyoti Sahu
- Department of Physiology, Institute of Biomedicine, Biomedicum Helsinki, University of Helsinki, FI-00014 Helsinki, Finland and Department of Cellular and Molecular Medicine, Molecular Endocrinology Laboratory, Katholieke Universiteit Leuven, Campus Gasthuisberg, BE-3000 Leuven, Belgium
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Pihlajamaa P, Sahu B, Lyly L, Aittomäki V, Hautaniemi S, Jänne OA. Tissue-specific pioneer factors associate with androgen receptor cistromes and transcription programs. EMBO J 2014; 33:312-26. [PMID: 24451200 DOI: 10.1002/embj.201385895] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Androgen receptor (AR) binds male sex steroids and mediates physiological androgen actions in target tissues. ChIP-seq analyses of AR-binding events in murine prostate, kidney and epididymis show that in vivo AR cistromes and their respective androgen-dependent transcription programs are highly tissue specific mediating distinct biological pathways. This high order of tissue specificity is achieved by the use of exclusive collaborating factors in the three androgen-responsive tissues. We find two novel collaborating factors for AR signaling in vivo--Hnf4α (hepatocyte nuclear factor 4α) in mouse kidney and AP-2α (activating enhancer binding protein 2α) in mouse epididymis--that define tissue-specific AR recruitment. In mouse prostate, FoxA1 serves for the same purpose. FoxA1, Hnf4α and AP-2α motifs are over-represented within unique AR-binding loci, and the cistromes of these factors show substantial overlap with AR-binding events distinct to each tissue type. These licensing or pioneering factors are constitutively bound to chromatin and guide AR to specific genomic loci upon hormone exposure. Collectively, liganded receptor and its DNA-response elements are required but not sufficient for establishment of tissue-specific transcription programs.
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Affiliation(s)
- Päivi Pihlajamaa
- Institute of Biomedicine University of Helsinki, Helsinki, Finland
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Sahu B, Laakso M, Pihlajamaa P, Ovaska K, Sinielnikov I, Hautaniemi S, Jänne OA. FoxA1 specifies unique androgen and glucocorticoid receptor binding events in prostate cancer cells. Cancer Res 2012; 73:1570-80. [PMID: 23269278 DOI: 10.1158/0008-5472.can-12-2350] [Citation(s) in RCA: 168] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The forkhead protein FoxA1 has functions other than a pioneer factor, in that its depletion brings about a significant redistribution in the androgen receptor (AR) and glucocorticoid receptor (GR) cistromes. In this study, we found a novel function for FoxA1 in defining the cell-type specificity of AR- and GR-binding events in a distinct fashion, namely, for AR in LNCaP-1F5 cells and for GR in VCaP cells. We also found different, cell-type and receptor-specific compilations of cis-elements enriched adjacent to the AR- and GR-binding sites. The AR pathway is central in prostate cancer biology, but the role of GR is poorly known. We find that AR and GR cistromes and transcription programs exhibit significant overlap, and GR regulates a large number of genes considered to be AR pathway-specific. This raises questions about the role of GR in maintaining the AR pathway under androgen-deprived conditions in castration-resistant prostate cancer patients. However, in the presence of androgen, ligand-occupied GR acts as a partial antiandrogen and attenuates the AR-dependent transcription program. .
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Affiliation(s)
- Biswajyoti Sahu
- Institute of Biomedicine and Research Programs Unit, Genome-Scale Biology, Biomedicum Helsinki, University of Helsinki, Finland
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9
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Abstract
To enable studies of androgen signaling in different tissues in vivo, we generated an androgen receptor (AR) reporter mouse line by inserting a luciferase gene construct into the murine genome. The construct is driven by four copies of androgen-responsive elements from the mouse sex-limited protein gene (slp-HRE2) and a minimal thymidine kinase promoter. Luciferase activity was readily measurable in a number of murine tissues, including prostate, lung, testis, brain, and skeletal muscle, and testosterone administration elicited a significant increase in reporter gene activity in these tissues. Consumption of isoflavonoid genistein is linked to reduced risk of prostate cancer, but direct effects of genistein on the AR pathway are not well understood. To examine androgen-modulating activity of genistein in vivo, male mice received daily doses of genistein (10 mg/kg) for 5 d. In intact males, genistein was antiandrogenic in testis, prostate, and brain, and it attenuated reporter gene activity by 50-80%. In castrated males, genistein exhibited significant androgen agonistic activity in prostate and brain by increasing reporter gene activity over 2-fold in both tissues. No antiandrogenic action was seen in lung or skeletal muscle of intact males. Gene expression profiling of the murine prostate under the same experimental conditions revealed that genistein modulates androgen-dependent transcription program in prostate in a fashion similar to that observed in reporter mice by luciferase expression. In conclusion, genistein is a partial androgen agonist/antagonist in some but not in all mouse tissues and should be considered as a tissue-specific AR modulator.
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Affiliation(s)
- Päivi Pihlajamaa
- Institute of Biomedicine, Physiology, Biomedicum Helsinki, University of Helsinki, and Department of Clinical Chemistry, Helsinki University Central Hospital, P.O. Box 63, FI-00014 Helsinki, Finland
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Mikkonen L, Pihlajamaa P, Sahu B, Zhang FP, Jänne OA. Androgen receptor and androgen-dependent gene expression in lung. Mol Cell Endocrinol 2010; 317:14-24. [PMID: 20035825 DOI: 10.1016/j.mce.2009.12.022] [Citation(s) in RCA: 171] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2009] [Revised: 12/16/2009] [Accepted: 12/16/2009] [Indexed: 10/20/2022]
Abstract
The androgen receptor (AR) mediates the effects of male sex steroids. There are major sex differences in lung development and pathologies, including lung cancer. In this report, we show that Ar is mainly expressed in type II pneumocytes and the bronchial epithelium of murine lung and that androgen treatment increases AR protein levels in lung cells. Androgen administration altered significantly murine lung gene expression profiles; for example, by up-regulating transcripts involved in oxygen transport and down-regulating those in DNA repair and DNA recombination. Androgen exposure also affected the gene expression profile in a human lung adenocarcinoma-derived cell line, A549, by up- or down-regulating significantly some 200 transcripts, including down-regulation of genes involved in cell respiration. Dexamethasone treatment of A549 cells augmented expression of transcript sets that overlapped in part with those up-regulated by androgen in these cells. Moreover, a human lung cancer tissue array revealed that different lung cancer types are all AR-positive. Our results indicate that adult lung is an AR target tissue and suggest that AR plays a role in lung cancer biology.
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Affiliation(s)
- Laura Mikkonen
- Biomedicum Helsinki, Institute of Biomedicine (Physiology), University of Helsinki, FI-00014 Helsinki, Finland
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