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Iñiguez-Muñoz S, Llinàs-Arias P, Ensenyat-Mendez M, Bedoya-López AF, Orozco JIJ, Cortés J, Roy A, Forsberg-Nilsson K, DiNome ML, Marzese DM. Hidden secrets of the cancer genome: unlocking the impact of non-coding mutations in gene regulatory elements. Cell Mol Life Sci 2024; 81:274. [PMID: 38902506 DOI: 10.1007/s00018-024-05314-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 12/07/2023] [Accepted: 06/06/2024] [Indexed: 06/22/2024]
Abstract
Discoveries in the field of genomics have revealed that non-coding genomic regions are not merely "junk DNA", but rather comprise critical elements involved in gene expression. These gene regulatory elements (GREs) include enhancers, insulators, silencers, and gene promoters. Notably, new evidence shows how mutations within these regions substantially influence gene expression programs, especially in the context of cancer. Advances in high-throughput sequencing technologies have accelerated the identification of somatic and germline single nucleotide mutations in non-coding genomic regions. This review provides an overview of somatic and germline non-coding single nucleotide alterations affecting transcription factor binding sites in GREs, specifically involved in cancer biology. It also summarizes the technologies available for exploring GREs and the challenges associated with studying and characterizing non-coding single nucleotide mutations. Understanding the role of GRE alterations in cancer is essential for improving diagnostic and prognostic capabilities in the precision medicine era, leading to enhanced patient-centered clinical outcomes.
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Affiliation(s)
- Sandra Iñiguez-Muñoz
- Cancer Epigenetics Laboratory at the Cancer Cell Biology Group, Institut d'Investigació Sanitària Illes Balears (IdISBa), Palma, Spain
| | - Pere Llinàs-Arias
- Cancer Epigenetics Laboratory at the Cancer Cell Biology Group, Institut d'Investigació Sanitària Illes Balears (IdISBa), Palma, Spain
| | - Miquel Ensenyat-Mendez
- Cancer Epigenetics Laboratory at the Cancer Cell Biology Group, Institut d'Investigació Sanitària Illes Balears (IdISBa), Palma, Spain
| | - Andrés F Bedoya-López
- Cancer Epigenetics Laboratory at the Cancer Cell Biology Group, Institut d'Investigació Sanitària Illes Balears (IdISBa), Palma, Spain
| | - Javier I J Orozco
- Saint John's Cancer Institute, Providence Saint John's Health Center, Santa Monica, CA, USA
| | - Javier Cortés
- International Breast Cancer Center (IBCC), Pangaea Oncology, Quiron Group, 08017, Barcelona, Spain
- Medica Scientia Innovation Research SL (MEDSIR), 08018, Barcelona, Spain
- Faculty of Biomedical and Health Sciences, Department of Medicine, Universidad Europea de Madrid, 28670, Madrid, Spain
| | - Ananya Roy
- Department of Immunology, Genetics and Pathology and Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Karin Forsberg-Nilsson
- Department of Immunology, Genetics and Pathology and Science for Life Laboratory, Uppsala University, Uppsala, Sweden
- University of Nottingham Biodiscovery Institute, Nottingham, UK
| | - Maggie L DiNome
- Department of Surgery, Duke University School of Medicine, Durham, NC, USA
| | - Diego M Marzese
- Cancer Epigenetics Laboratory at the Cancer Cell Biology Group, Institut d'Investigació Sanitària Illes Balears (IdISBa), Palma, Spain.
- Department of Surgery, Duke University School of Medicine, Durham, NC, USA.
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Gyüre Z, Póti Á, Németh E, Szikriszt B, Lózsa R, Krawczyk M, Richardson AL, Szüts D. Spontaneous mutagenesis in human cells is controlled by REV1-Polymerase ζ and PRIMPOL. Cell Rep 2023; 42:112887. [PMID: 37498746 DOI: 10.1016/j.celrep.2023.112887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 06/09/2023] [Accepted: 07/13/2023] [Indexed: 07/29/2023] Open
Abstract
Translesion DNA synthesis (TLS) facilitates replication over damaged or difficult-to-replicate templates by employing specialized DNA polymerases. We investigate the effect on spontaneous mutagenesis of three main TLS control mechanisms: REV1 and PCNA ubiquitylation that recruit TLS polymerases and PRIMPOL that creates post-replicative gaps. Using whole-genome sequencing of cultured human RPE-1 cell clones, we find that REV1 and Polymerase ζ are wholly responsible for one component of base substitution mutagenesis that resembles homologous recombination deficiency, whereas the remaining component that approximates oxidative mutagenesis is reduced in PRIMPOL-/- cells. Small deletions in short repeats appear in REV1-/-PCNAK164R/K164R double mutants, revealing an alternative TLS mechanism. Also, 500-5,000 bp deletions appear in REV1-/- and REV3L-/- mutants, and chromosomal instability is detectable in REV1-/-PRIMPOL-/- cells. Our results indicate that TLS protects the genome from deletions and large rearrangements at the expense of being responsible for the majority of spontaneous base substitutions.
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Affiliation(s)
- Zsolt Gyüre
- Institute of Enzymology, Research Centre for Natural Sciences, 1117 Budapest, Hungary; Doctoral School of Molecular Medicine, Semmelweis University, 1085 Budapest, Hungary; Turbine Simulated Cell Technologies, 1027 Budapest, Hungary
| | - Ádám Póti
- Institute of Enzymology, Research Centre for Natural Sciences, 1117 Budapest, Hungary
| | - Eszter Németh
- Institute of Enzymology, Research Centre for Natural Sciences, 1117 Budapest, Hungary
| | - Bernadett Szikriszt
- Institute of Enzymology, Research Centre for Natural Sciences, 1117 Budapest, Hungary
| | - Rita Lózsa
- Institute of Enzymology, Research Centre for Natural Sciences, 1117 Budapest, Hungary
| | - Michał Krawczyk
- Institute of Enzymology, Research Centre for Natural Sciences, 1117 Budapest, Hungary
| | | | - Dávid Szüts
- Institute of Enzymology, Research Centre for Natural Sciences, 1117 Budapest, Hungary; National Laboratory for Drug Research and Development, 1117 Budapest, Hungary.
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3
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Oubaddou Y, Oukabli M, Fenniche S, Elktaibi A, Elochi MR, Al Bouzidi A, Qmichou Z, Dakka N, Diorio C, Richter A, Bakri Y, Ameziane El Hassani R. BRCA1 Promoter Hypermethylation in Malignant Breast Tumors and in the Histologically Normal Adjacent Tissues to the Tumors: Exploring Its Potential as a Biomarker and Its Clinical Significance in a Translational Approach. Genes (Basel) 2023; 14:1680. [PMID: 37761820 PMCID: PMC10530732 DOI: 10.3390/genes14091680] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 08/22/2023] [Accepted: 08/24/2023] [Indexed: 09/29/2023] Open
Abstract
The hypermethylation status of the promoter region of the breast cancer 1 (BRCA1), a well-known tumor suppressor gene, has been extensively investigated in the last two decades as a potential biomarker for breast cancer. In this retrospective study, we investigated the prevalence of BRCA1 promoter methylation in 84 human breast tissues, and we correlated this epigenetic silencing with the clinical and histopathological parameters of breast cancer. We used methylation-specific PCR (MSP) to analyze BRCA1 promoter hypermethylation in 48 malignant breast tumors (MBTs), 15 normal adjacent tissues (NATs), and 21 benign breast lesions (BBLs). The results showed that BRCA1 promoter hypermethylation was higher in MBTs (20/48; 41.67%) and NATs (7/15; 46.67%) compared to BBLs (4/21; 19.05%). The high percentage of BRCA1 hypermethylation in the histologically normal adjacent tissues to the tumors (NATs) suggests the involvement of this epigenetic silencing as a potential biomarker of the early genomic instability in NATs surrounding the tumors. The detection of BRCA1 promoter hypermethylation in BBLs reinforces this suggestion, knowing that a non-negligible rate of benign breast lesions was reported to evolve into cancer. Moreover, our results indicated that the BRCA1 promoter hypermethylated group of MBTs exhibited higher rates of aggressive features, as indicated by the SBR III grade (14/19; 73.68%), elevated Ki67 levels (13/16; 81.25%), and Her2 receptor overexpression (5/20; 25%). Finally, we observed a concordance (60%) in BRCA1 promoter hypermethylation status between malignant breast tumors and their paired histologically normal adjacent tissues. This study highlights the role of BRCA1 promoter hypermethylation as a potential useful biomarker of aggressiveness in MBTs and as an early marker of genomic instability in both histological NATs and BBLs.
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Affiliation(s)
- Yassire Oubaddou
- Laboratory of Biology of Human Pathologies (BioPatH), Faculty of Sciences, Mohammed V University in Rabat, Rabat 10001, Morocco; (Y.O.); (S.F.); (N.D.); (Y.B.)
| | - Mohamed Oukabli
- Service of Anatomical Pathology, Military Hospital of Instruction Mohammed V (HMIMV-R), Faculty of Medicine and Pharmacy, Mohammed V University in Rabat, Rabat 10001, Morocco; (M.O.); (A.E.); (M.R.E.)
| | - Salma Fenniche
- Laboratory of Biology of Human Pathologies (BioPatH), Faculty of Sciences, Mohammed V University in Rabat, Rabat 10001, Morocco; (Y.O.); (S.F.); (N.D.); (Y.B.)
| | - Abderrahim Elktaibi
- Service of Anatomical Pathology, Military Hospital of Instruction Mohammed V (HMIMV-R), Faculty of Medicine and Pharmacy, Mohammed V University in Rabat, Rabat 10001, Morocco; (M.O.); (A.E.); (M.R.E.)
| | - Mohamed Reda Elochi
- Service of Anatomical Pathology, Military Hospital of Instruction Mohammed V (HMIMV-R), Faculty of Medicine and Pharmacy, Mohammed V University in Rabat, Rabat 10001, Morocco; (M.O.); (A.E.); (M.R.E.)
| | | | - Zineb Qmichou
- Medical Biotechnology Center, Moroccan Foundation for Advanced Science, Innovation and Research (MAScIR), Rabat 10001, Morocco;
| | - Nadia Dakka
- Laboratory of Biology of Human Pathologies (BioPatH), Faculty of Sciences, Mohammed V University in Rabat, Rabat 10001, Morocco; (Y.O.); (S.F.); (N.D.); (Y.B.)
| | - Caroline Diorio
- Cancer Research Center, CHU de Québec—Université Laval Research Center, Oncology Division, Québec, QC G1R 3S3, Canada;
- Department of Social and Preventive Medicine, Faculty of Medicine, Université Laval, Québec, QC GIV 0A6, Canada
| | - Antje Richter
- Institute for Genetics, University Giessen, 35392 Giessen, Germany;
| | - Youssef Bakri
- Laboratory of Biology of Human Pathologies (BioPatH), Faculty of Sciences, Mohammed V University in Rabat, Rabat 10001, Morocco; (Y.O.); (S.F.); (N.D.); (Y.B.)
| | - Rabii Ameziane El Hassani
- Laboratory of Biology of Human Pathologies (BioPatH), Faculty of Sciences, Mohammed V University in Rabat, Rabat 10001, Morocco; (Y.O.); (S.F.); (N.D.); (Y.B.)
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Al-Moghrabi N, Al-Showimi M, Al-Yousef N, AlOtai L. MicroRNA-155-5p, Reduced by Curcumin-Re-Expressed Hypermethylated BRCA1, Is a Molecular Biomarker for Cancer Risk in BRCA1-methylation Carriers. Int J Mol Sci 2023; 24:ijms24109021. [PMID: 37240365 DOI: 10.3390/ijms24109021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 05/09/2023] [Accepted: 05/17/2023] [Indexed: 05/28/2023] Open
Abstract
Constitutional BRCA1-methylation is a cancer risk factor for breast (BC) and ovarian (OC) cancer. MiR-155, regulated by BRCA1, is a multifunctional microRNA that plays a crucial role in the immune system. The present study assessed the modulation of miR-155-5p expression in peripheral white blood cells (WBCs) of BC and OC patients and cancer-free (CF) BRCA1-methylation female carriers. Additionally, we investigated the potential of curcumin to suppress miR-155-5p in BRCA1-deficient breast cancer cell lines. MiR-155-5p expression was measured using a stem-loop RT-qPCR method. Gene expression levels were determined using qRT-PCR and immunoblotting. MiR-155-5p was more highly expressed in the BRCA1-hypermethylated HCC-38 and UACC-3199 BC cell lines than in the BRCA1-mutated (HCC-1937) and WT BRCA1 (MDA-MB-321) cell lines. Curcumin suppressed miR-155-5p in the HCC-38 cells but not in the HCC-1937 cells via the re-expression of BRCA1. Elevated levels of miR-155-5p were detected in patients with non-aggressive and localized breast tumors and in patients with late-stage aggressive ovarian tumors, as well as in CF BRCA1-methylation carriers. Notably, IL2RG levels were reduced in the OC and CF groups but not in the BC group. Together, our findings suggest opposing effects of WBC miR-155-5p, according to the cell and cancer type. In addition, the results point to miR-155-5p as a candidate biomarker of cancer risk among CF-BRCA1-methylation carriers.
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Affiliation(s)
- Nisreen Al-Moghrabi
- Cancer Epigenetics Section, Department of Molecular Oncology, King Faisal Specialist Hospital and Research Centre, Riyadh 11211, Saudi Arabia
| | - Maram Al-Showimi
- Cancer Epigenetics Section, Department of Molecular Oncology, King Faisal Specialist Hospital and Research Centre, Riyadh 11211, Saudi Arabia
| | - Nujoud Al-Yousef
- Cancer Epigenetics Section, Department of Molecular Oncology, King Faisal Specialist Hospital and Research Centre, Riyadh 11211, Saudi Arabia
| | - Lamya AlOtai
- Department of Life Sciences, College of Science & General Studies, Al Faisal University, Riyadh 11533, Saudi Arabia
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5
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Soman PS, Hemalatha A, Sreeramulu PN. Expression of BRCA1 by immunohistochemistry and its association with ER, PR, Her2neu status in infiltrative ductal carcinoma of breast. J Cancer Res Ther 2023; 19:S706-S711. [PMID: 38384043 DOI: 10.4103/jcrt.jcrt_639_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 07/31/2022] [Indexed: 02/23/2024]
Abstract
BACKGROUND Breast cancer is a heterogeneous disease, which differs in its clinical behaviors and responses to treatment and outcome. The prognosis of breast cancer depends on histopathological parameters and molecular subtypes. Among more than 300 genes, which are involved in the pathogenesis of breast cancer tumor suppressor gene such as BRCA1 is known to play a significant role in hereditary cancers. However, its role in sporadic cases of infiltrating ductal carcinoma is yet to be established. AIMS AND OBJECTIVES To evaluate the expression of BRCA1 in infiltrative ductal carcinoma and to analyze the association of BRCA1 with histopathological parameters and estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor2 (Her2) neu expression. MATERIALS AND METHODS This was a laboratory-based exploratory study in which 56 patients with infiltrative ductal carcinoma who underwent radical mastectomy from October 2019 to July 2021 were included. Patients with chemotherapy and radiotherapy, trucut biopsies, and incomplete patient details were excluded. Immunostaining for BRCA1 was performed. Individual clinicopathological parameters were compared with the BRCA1 mutation. Statistical analysis was done using SPSS 22. A P value of < 0.05 was considered statistically significant. RESULTS Among 56 cases of IDC, 18 cases (32.1%) showed BRCA1 mutation. BRCA1 mutation was associated with postmenopausal age, larger tumor size, lower tumor grade, and higher tumor staging. When we analyzed the biomarkers with BRCA1 mutation, it showed a negative association with ER, PR, and Her2 neu and a high Ki67 proliferation index. No family history of breast carcinoma was seen in 34/56 patients where history was available. CONCLUSION Our study showed BRCA1 mutation in 32.1% and associated with postmenopausal age group, larger tumor size, and higher staging and negative hormonal status of breast carcinoma.
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MESH Headings
- Humans
- Female
- Breast Neoplasms/pathology
- Receptors, Estrogen/genetics
- Receptors, Estrogen/metabolism
- Receptors, Progesterone/genetics
- Receptors, Progesterone/metabolism
- Immunohistochemistry
- Receptor, ErbB-2/genetics
- Receptor, ErbB-2/metabolism
- Mastectomy
- Carcinoma, Ductal, Breast/genetics
- Carcinoma, Ductal, Breast/therapy
- Carcinoma, Ductal, Breast/metabolism
- Biomarkers, Tumor/genetics
- Biomarkers, Tumor/metabolism
- BRCA1 Protein/genetics
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Affiliation(s)
- Princy S Soman
- Department of Pathology, Sri Devaraj Urs Medical College, Kolar, Karnataka, India Affliated to Sri Devaraj Urs Academy of Higher Education and Research, Tamaka, Kolar, Karnataka, India
| | - A Hemalatha
- Department of Pathology, Sri Devaraj Urs Medical College, Kolar, Karnataka, India Affliated to Sri Devaraj Urs Academy of Higher Education and Research, Tamaka, Kolar, Karnataka, India
| | - P N Sreeramulu
- Department of Surgery, Sri Devaraj Urs Medical College, Kolar, Karnataka, India Affliated to Sri Devaraj Urs Academy of Higher Education and Research, Tamaka, Kolar, Karnataka, India
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6
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Hambalek JA, Kong JE, Brown C, Munoz HE, Horn T, Bogumil M, Quick E, Ozcan A, Di Carlo D. Methylation-Sensitive Loop-Mediated Isothermal Amplification (LAMP): Nucleic Acid Methylation Detection through LAMP with Mobile Fluorescence Readout. ACS Sens 2021; 6:3242-3252. [PMID: 34467761 DOI: 10.1021/acssensors.1c00902] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The emergence of epigenetic gene regulation and its role in disease have motivated a growing field of epigenetic diagnostics for risk assessment and screening. In particular, irregular cytosine DNA base methylation has been implicated in several diseases, yet the methods for detecting these epigenetic marks are limited to lengthy protocols requiring bulky and costly equipment. We demonstrate a simple workflow for detecting methylated CpG dinucleotides in synthetic and genomic DNA samples using methylation-sensitive restriction enzyme digestion followed by loop-mediated isothermal amplification. We additionally demonstrate a cost-effective mobile fluorescence reader comprising a light-emitting diode bundle, a mirror, and optical fibers to transduce fluorescence signals associated with DNA amplification. The workflow can be performed in approximately 1 h, requiring only a simple heat source, and can therefore provide a foundation for distributable point-of-care testing of DNA methylation levels.
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Affiliation(s)
- Jacob Amos Hambalek
- Department of Bioengineering, University of California Los Angeles, Los Angeles, California 90095, United States
| | - Janay Elise Kong
- Department of Bioengineering, University of California Los Angeles, Los Angeles, California 90095, United States
| | - Calvin Brown
- Department of Electrical & Computer Engineering, University of California Los Angeles, Los Angeles, California 90095, United States
| | - Hector Enrique Munoz
- Department of Bioengineering, University of California Los Angeles, Los Angeles, California 90095, United States
| | - Thomas Horn
- Department of Bioengineering, University of California Los Angeles, Los Angeles, California 90095, United States
| | - Michael Bogumil
- Department of Bioengineering, University of California Los Angeles, Los Angeles, California 90095, United States
| | - Eleni Quick
- Department of Bioengineering, University of California Los Angeles, Los Angeles, California 90095, United States
| | - Aydogan Ozcan
- Department of Electrical & Computer Engineering, University of California Los Angeles, Los Angeles, California 90095, United States
| | - Dino Di Carlo
- Department of Bioengineering, University of California Los Angeles, Los Angeles, California 90095, United States
- Jonsson Comprehensive Cancer Center, University of California Los Angeles, Los Angeles, California 90024, United States
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7
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Al-Yousef N, Shinwari Z, Al-Shahrani B, Al-Showimi M, Al-Moghrabi N. Curcumin induces re‑expression of BRCA1 and suppression of γ synuclein by modulating DNA promoter methylation in breast cancer cell lines. Oncol Rep 2020; 43:827-838. [PMID: 32020216 PMCID: PMC7041105 DOI: 10.3892/or.2020.7473] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Accepted: 12/30/2019] [Indexed: 01/09/2023] Open
Abstract
Restoration of normal DNA promoter methylation and expression states of cancer-related genes may be an option for the prevention as well as the treatment of several types of cancer. Constitutional promoter methylation of BRCA1 DNA repair associated (BRCA1) gene is linked with a high risk of developing breast and ovarian cancer. Furthermore, hypomethylation of the proto-oncogene γ synuclein (SNCG) is associated with the metastasis of breast and ovarian cancer and reduced disease-free survival (DFS). In the present study, we evaluated the potential of curcumin to re-express hypermethylated BRCA1 and to suppress hypomethylated SNCG in triple-negative breast cancer (TNBC) cell line HCC-38, the estrogen receptor-negative/progesterone receptor-negative (ER−/PR−) cell line UACC-3199, and the ER+/PR+ cell line T47D. The cells were treated with 5 and 10 µM curcumin for 6 days and with 5-aza-2′-deoxycytidine (5′-aza-CdR) for 48 h. Methylation-specific PCR and bisulfite pyrosequencing assays were used to assess DNA promoter methylation while gene expression levels were analyzed using quantitative real-time PCR and immunoblotting. We found that curcumin treatment restored BRCA1 gene expression by reducing the DNA promoter methylation level in HCC-38 and UACC-3199 cells and that it suppressed the expression of SNCG by inducing DNA promoter methylation in T47D cells. Notably, 5′-aza-CdR restored BRCA1 gene expression only in UACC-3199, and not in HCC-38 cells. Curcumin-induced hypomethylation of the BRCA1 promoter appears to be realized through the upregulation of the ten-eleven translocation 1 (TET1) gene, whereas curcumin-induced hypermethylation of SNCG may be realized through the upregulation of the DNA methyltransferase 3 (DNMT3) and the downregulation of TET1. Notably, miR-29b was found to be reversely expressed compared to TET1 in curcumin- and 5′-aza-CdR-treated cells, suggesting its involvement in the regulation of TET1. Overall, our results indicate that curcumin has an intrinsic dual function on DNA promoter methylation. We believe that curcumin may be considered a promising therapeutic option for treating TNBC patients in addition to preventing breast and ovarian cancer, particularly in cancer-free females harboring methylated BRCA1.
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Affiliation(s)
- Nujoud Al-Yousef
- Cancer Epigenetics Section, Department of Molecular Oncology, King Faisal Specialist Hospital and Research Centre, Riyadh 11211, Kingdom of Saudi Arabia
| | - Zakia Shinwari
- Cancer Epigenetics Section, Department of Molecular Oncology, King Faisal Specialist Hospital and Research Centre, Riyadh 11211, Kingdom of Saudi Arabia
| | - Bushra Al-Shahrani
- Cancer Epigenetics Section, Department of Molecular Oncology, King Faisal Specialist Hospital and Research Centre, Riyadh 11211, Kingdom of Saudi Arabia
| | - Maram Al-Showimi
- Cancer Epigenetics Section, Department of Molecular Oncology, King Faisal Specialist Hospital and Research Centre, Riyadh 11211, Kingdom of Saudi Arabia
| | - Nisreen Al-Moghrabi
- Cancer Epigenetics Section, Department of Molecular Oncology, King Faisal Specialist Hospital and Research Centre, Riyadh 11211, Kingdom of Saudi Arabia
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Donovan MG, Selmin OI, Doetschman TC, Romagnolo DF. Epigenetic Activation of BRCA1 by Genistein In Vivo and Triple Negative Breast Cancer Cells Linked to Antagonism toward Aryl Hydrocarbon Receptor. Nutrients 2019; 11:nu11112559. [PMID: 31652854 PMCID: PMC6893467 DOI: 10.3390/nu11112559] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 10/16/2019] [Accepted: 10/17/2019] [Indexed: 12/24/2022] Open
Abstract
Triple negative breast cancers (TNBC) are the most aggressive and lethal breast cancers (BC). The aryl hydrocarbon receptor (AHR) is often overexpressed in TNBC, and its activation results in the epigenetic silencing of BRCA1, which is a necessary factor for the transcriptional activation of estrogen receptor (ER)α. The dietary isoflavone genistein (GEN) modulates BRCA1 CpG methylation in BC cells. The purpose of this study was to investigate the effect of GEN on BRCA1 epigenetic regulation and AHR activity in vivo and TNBC cells. Mice were administered a control or GEN-enriched (4 and 10 ppm) diet from gestation through post-natal day 50. Mammary tissue was analyzed for changes in BRCA1 regulation and AhR activity. TNBC cells with constitutively hypermethylated BRCA1 (HCC38) and MCF7 cells were used. Protein levels and mRNA expression were measured by Western blot and real-time PCR, respectively. BRCA1 promoter occupancy and CpG methylation were analyzed by chromatin immunoprecipitation and methylation-specific PCR, respectively. Cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. GEN administered in the diet dose-dependently decreased basal Brca1 methylation and AHR activity in the mammary gland of adult mice. HCC38 cells were found to overexpress constitutively active AHR in parallel with BRCA1 hypermethylation. The treatment of HCC38 cells with GEN upregulated BRCA1 protein levels, which was attributable to decreased CpG methylation and AHR binding at BRCA1 exon 1a. In MCF7 cells, GEN prevented the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-dependent localization of AHR at the BRCA1 gene. These effects were consistent with those elicited by control AHR antagonists galangin (GAL), CH-223191, and α-naphthoflavone. The pre-treatment with GEN sensitized HCC38 cells to the antiproliferative effects of 4-hydroxytamoxifen. We conclude that the dietary compound GEN may be effective for the prevention and reversal of AHR-dependent BRCA1 hypermethylation, and the restoration of ERα-mediated response, thus imparting the sensitivity of TNBC to antiestrogen therapy.
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Affiliation(s)
- Micah G Donovan
- Cancer Biology Graduate Interdisciplinary Program, The University of Arizona, Tucson, AZ 85724, USA.
- The University of Arizona Cancer Center, The University of Arizona, Tucson, AZ 85724, USA.
| | - Ornella I Selmin
- The University of Arizona Cancer Center, The University of Arizona, Tucson, AZ 85724, USA.
- Department of Nutritional Sciences, The University of Arizona, Tucson, AZ 85721, USA.
| | - Thomas C Doetschman
- The University of Arizona Cancer Center, The University of Arizona, Tucson, AZ 85724, USA.
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, AZ 85724, USA.
| | - Donato F Romagnolo
- The University of Arizona Cancer Center, The University of Arizona, Tucson, AZ 85724, USA.
- Department of Nutritional Sciences, The University of Arizona, Tucson, AZ 85721, USA.
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9
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Zou H, Lan Z, Zhou M, Lu W. Promoter methylation and Hoxd4 regulate UII mRNA tissue-specific expression in olive flounder (paralichthys olivaceus). Gen Comp Endocrinol 2018. [PMID: 29522756 DOI: 10.1016/j.ygcen.2018.03.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The peptide urotensin II (UII) mediates multiple physiology effects in mammals and fishes, and UII expression shows a tissue-specific pattern. However the mechanism is still unknown. In the present study high level of UII mRNA was detected in the caudal neurosecretory system (CNSS) of the olive flounder when compared to other tissues. We examined whether epigenetic mechanisms of DNA methylation are involved in UII gene expression. Methylation DNA immune precipitation (MeDIP) assay showed low methylation of UII promoter in CNSS tissue compared with muscle and spinal cord. Methylation of UII promoter was further assessed through bisulphate sequencing analysis. Low level methylation (31%) in CpG island of UII promoter was detected in CNSS tissue, while methylation status in muscle and spinal cord was 89% and 91%, respectively. In addition, high conserved sites of Hoxd4 in UII promoter were found. Activation of Hoxd4 mRNA using transretinoic acid (RA) resulted in 18-fold increase of UII mRNA expression in CNSS and high locomotor activity in medaka, confirming that Hoxd4 is also involved in UII gene transcriptional regulation. Taken together, our data provide the first evidence of the epigenetic mechanism of promoter methylation in transcriptional regulation of UII expression in a tissue-specific manner, and Hoxd4 may also participate in UII gene transcription in flounder.
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Affiliation(s)
- Huafeng Zou
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai 201306, China
| | - Zhaohui Lan
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai 201306, China
| | - Mo Zhou
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China
| | - Weiqun Lu
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, Shanghai 201306, China.
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10
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Li Y, Dong W, Shan X, Hong H, Liu Y, Liu Y, Liu X, Zhang X, Zhang J. The anti-tumor effects of Mfn2 in breast cancer are dependent on promoter DNA methylation, the P21 Ras motif and PKA phosphorylation site. Oncol Lett 2018; 15:8011-8018. [PMID: 29731912 DOI: 10.3892/ol.2018.8314] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Accepted: 02/08/2018] [Indexed: 12/20/2022] Open
Abstract
Mitofusin 2 (Mfn2) is expressed in numerous human tissues and serves a pivotal role in cell proliferation. However, Mfn2 is considered as an anti-tumor gene, and is silenced in human malignant tumors, including those of breast cancer. However, the mechanisms contributing to Mfn2 silencing and the mechanism of its anti-tumor function in breast cancer remain unclear. In the present study, hypoexpression of Mfn2, and hypermethylation of its promoter, was confirmed in human breast cancer cells and in breast cancer tissues by reverse transcription-quantitative polymerase chain reaction (PCR) and methylation specific PCR, respectively. Chemical demethylation treatment with 5-aza-2'-deoxycytidine upregulated the mRNA expression level of Mfn2 in MCF-7 cells in a dose-dependent manner. In addition, overexpression of Mfn2 repressed the proliferation, migration and invasion of MCF-7 cells, mediated by inhibition of the Ras-extracellular signal-regulated kinase (ERK)1/2 signaling pathway. However, overexpression of Mfn2 with deletion of the p21Ras motif (Mfn2ΔRas) and protein kinase A (PKA) phosphorylation site (Mfn2ΔPKA) partially reduced the anti-tumor function of Mfn2, and inhibited the Ras-ERK1/2 signaling pathway. Taken together, the present study confirmed the anti-tumor effects of Mfn2 in human breast cancer and clarified that the mechanism of its anti-tumor functions includes promoter DNA methylation, the P21Ras binding site and PKA phosphorylation.
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Affiliation(s)
- Yufeng Li
- The Cancer Institute, Affiliated Tangshan People's Hospital of North China University of Science and Technology, Tangshan, Hebei 063001, P.R. China
| | - Wenyue Dong
- Department of Anesthesiology, Affiliated Tangshan People's Hospital of North China University of Science and Technology, Tangshan, Hebei 063001, P.R. China
| | - Xijin Shan
- Department of Surgery, Rizhao Port Hospital, Rizhao, Shandong 276800, P.R. China
| | - Hui Hong
- Department of Head, Neck and Breast Surgery, Shangrao People's Hospital, Shangrao, Jiangxi 334000, P.R. China
| | - Yan Liu
- Department of Bioengineering, College of Life Sciences, North China University of Science and Technology, Tangshan, Hebei 063000, P.R. China
| | - Yankun Liu
- The Cancer Institute, Affiliated Tangshan People's Hospital of North China University of Science and Technology, Tangshan, Hebei 063001, P.R. China
| | - Xiaohui Liu
- Department of Thoracic Surgery, Affiliated Tangshan People's Hospital of North China University of Science and Technology, Tangshan, Hebei 063001, P.R. China
| | - Xiaojun Zhang
- Department of Internal Medicine, Affiliated Zunhua People's Hospital of North China University of Science and Technology, Zunhua, Hebei 064200, P.R. China
| | - Jinghua Zhang
- The Cancer Institute, Affiliated Tangshan People's Hospital of North China University of Science and Technology, Tangshan, Hebei 063001, P.R. China
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11
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Seelan RS, Mukhopadhyay P, Pisano MM, Greene RM. Effects of 5-Aza-2'-deoxycytidine (decitabine) on gene expression. Drug Metab Rev 2018; 50:193-207. [PMID: 29455551 DOI: 10.1080/03602532.2018.1437446] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
5-Aza-2'-deoxycytidine (AzaD), also known as Decitabine, is a deoxycytidine analog that is typically used to activate methylated and silenced genes by promoter demethylation. However, a survey of the scientific literature indicates that promoter demethylation may not be the only (or, indeed, the major) mechanism by which AzaD affects gene expression. Regulation of gene expression by AzaD can occur in several ways, including some that are independent of DNA demethylation. Results from several studies indicate that the effect of AzaD on gene expression is highly context-dependent and can differ for the same gene under different environmental settings. This may, in part, be due to the nature of the silencing mechanism(s) involved - DNA methylation, repressive histone modifications, or a combination of both. The varied effects of AzaD on such context-dependent regulation of gene expression may underlie some of the diverse responses exhibited by patients undergoing AzaD therapy. In this review, we describe the salient properties of AzaD with particular emphasis on its diverse effects on gene expression, aspects that have barely been discussed in most reviews of this interesting drug.
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Affiliation(s)
- Ratnam S Seelan
- a Department of Surgical and Hospital Dentistry, Division of Craniofacial Development and Anomalies , ULSD, University of Louisville , Louisville , KY , USA
| | - Partha Mukhopadhyay
- a Department of Surgical and Hospital Dentistry, Division of Craniofacial Development and Anomalies , ULSD, University of Louisville , Louisville , KY , USA
| | - M Michele Pisano
- a Department of Surgical and Hospital Dentistry, Division of Craniofacial Development and Anomalies , ULSD, University of Louisville , Louisville , KY , USA
| | - Robert M Greene
- a Department of Surgical and Hospital Dentistry, Division of Craniofacial Development and Anomalies , ULSD, University of Louisville , Louisville , KY , USA
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12
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Choudhury SR, Cui Y, Lubecka K, Stefanska B, Irudayaraj J. CRISPR-dCas9 mediated TET1 targeting for selective DNA demethylation at BRCA1 promoter. Oncotarget 2018; 7:46545-46556. [PMID: 27356740 PMCID: PMC5216816 DOI: 10.18632/oncotarget.10234] [Citation(s) in RCA: 223] [Impact Index Per Article: 37.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 05/30/2016] [Indexed: 12/24/2022] Open
Abstract
DNA hypermethylation at the promoter of tumour-suppressor genes is tightly correlated with their transcriptional repression and recognized as the hallmark of majority of cancers. Epigenetic silencing of tumour suppressor genes impairs their cellular functions and activates a cascade of events driving cell transformation and cancer progression. Here, we examine site-specific and spatiotemporal alteration in DNA methylation at a target region in BRCA1 gene promoter, a model tumour suppressor gene. We have developed a programmable CRISPR-Cas9 based demethylase tool containing the deactivated Cas9 (dCas9) fused to the catalytic domain (CD) of Ten-Eleven Translocation (TET) dioxygenase1 (TET1CD). The fusion protein selectively demethylates targeted regions within BRCA1 promoter as directed by the designed single-guide RNAs (sgRNA), leading to the transcriptional up-regulation of the gene. We also noticed the increment in 5-hydroxymethylation content (5-hmC) at the target DNA site undergoing the most profound demethylation. It confirms the catalytic activity of TET1 in TET1-dCas9 fusion proteins-mediated demethylation at these target sequences. The modular design of the fusion constructs presented here allows for the selective substitution of other chromatin or DNA modifying enzymes and for loci-specific targeting to uncover epigenetic regulatory pathways at gene promoters and other selected genomic regions.
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Affiliation(s)
- Samrat Roy Choudhury
- Department of Agricultural & Biological Engineering, Bindley Bioscience Centre, Purdue University, West Lafayette, IN 47907, USA
| | - Yi Cui
- Department of Agricultural & Biological Engineering, Bindley Bioscience Centre, Purdue University, West Lafayette, IN 47907, USA
| | - Katarzyna Lubecka
- Department of Nutrition Science, Purdue University, West Lafayette, IN 47907, USA
| | - Barbara Stefanska
- Department of Nutrition Science, Purdue University, West Lafayette, IN 47907, USA.,Purdue Centre for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
| | - Joseph Irudayaraj
- Department of Agricultural & Biological Engineering, Bindley Bioscience Centre, Purdue University, West Lafayette, IN 47907, USA.,Purdue Centre for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
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13
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Yamaguchi H, Du Y, Nakai K, Ding M, Chang SS, Hsu JL, Yao J, Wei Y, Nie L, Jiao S, Chang WC, Chen CH, Yu Y, Hortobagyi GN, Hung MC. EZH2 contributes to the response to PARP inhibitors through its PARP-mediated poly-ADP ribosylation in breast cancer. Oncogene 2018; 37:208-217. [PMID: 28925391 PMCID: PMC5786281 DOI: 10.1038/onc.2017.311] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 07/26/2017] [Accepted: 07/28/2017] [Indexed: 02/07/2023]
Abstract
Inhibitors against poly (ADP-ribose) polymerase (PARP) are promising targeted agents currently used to treat BRCA-mutant ovarian cancer and are in clinical trials for other cancer types, including BRCA-mutant breast cancer. To enhance the clinical response to PARP inhibitors (PARPis), understanding the mechanisms underlying PARPi sensitivity is urgently needed. Here, we show enhancer of zeste homolog 2 (EZH2), an enzyme that catalyzes H3 lysine trimethylation and associates with oncogenic function, contributes to PARPi sensitivity in breast cancer cells. Mechanistically, upon oxidative stress or alkylating DNA damage, PARP1 interacts with and attaches poly-ADP-ribose (PAR) chains to EZH2. PARylation of EZH2 by PARP1 then induces PRC2 complex dissociation and EZH2 downregulation, which in turn reduces EZH2-mediated H3 trimethylation. In contrast, inhibition of PARP by PARPi attenuates alkylating DNA damage-induced EZH2 downregulation, thereby promoting EZH2-mediated gene silencing and cancer stem cell property compared with PARPi-untreated cells. Moreover, the addition of an EZH2 inhibitor sensitizes the BRCA-mutant breast cells to PARPi. Thus, these results may provide a rationale for combining PARP and EZH2 inhibition as a therapeutic strategy for BRCA-mutated breast and ovarian cancers.
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Affiliation(s)
- H Yamaguchi
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Y Du
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - K Nakai
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - M Ding
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - S-S Chang
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - J L Hsu
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - J Yao
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Y Wei
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - L Nie
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - S Jiao
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - W-C Chang
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
- Graduate Institute of Biomedical Sciences and Center for Molecular Medicine, China Medical University, Taichung, Taiwan
| | - C-H Chen
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Y Yu
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - G N Hortobagyi
- Department of Breast Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - M-C Hung
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
- Graduate Institute of Biomedical Sciences and Center for Molecular Medicine, China Medical University, Taichung, Taiwan
- Department of Biotechnology, Asia University, Taichung, Taiwan
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14
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Chen Q, Wang L, Jiang M, Huang J, Jiang Z, Feng H, Ji Z. E2F1 interactive with BRCA1 pathway induces HCC two different small molecule metabolism or cell cycle regulation via mitochondrion or CD4+T to cytosol. J Cell Physiol 2017; 233:1213-1221. [PMID: 28474358 DOI: 10.1002/jcp.25988] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 05/03/2017] [Indexed: 12/24/2022]
Abstract
Breast cancer 1 (BRCA1) and E2F transcription factor 1 (E2F1) are related to metabolism and cell cycle regulation. However, the corresponding mechanism is not clear in HCC. High BRCA1 direct pathway was constructed with 11 molecules from E2F1 feedback-interactive network in HCC by GRNInfer based on 39 Pearson mutual positive corelation CC ≥0.25 molecules with E2F1. Integration of GRNInfer with GO, KEGG, BioCarta, GNF_U133A, UNIGENE_EST, Disease, GenMAPP databases by DAVID and MAS 3.0, E2F1 feedback-interactive BRCA1 indirect mitochondrion to cytosol pathway was identified as upstream LAPTM4B activation, feedback UNG, downstream BCAT1-HIST1H2AD-TK1 reflecting protein, and DNA binding with enrichment of small molecule metabolism; The corresponding BRCA1 indirect membrane to cytosol pathway as upstream CCNB2-NUSAP1 activation, feedback TTK-HIST1H2BJ-CENPF, downstream MCM4-TK1 reflecting ATP, and microtubule binding with enrichment of CD4+T-related cell cycle regulation in HCC. Therefore, we propose that E2F1 interactive with BRCA1 pathway induces HCC two different small molecule metabolism or cell cycle regulation via mitochondrion or CD4+T to cytosol. Knowledge analysis demonstrates our E2F1 feedback-interactive BRCA1 pathway wide disease distribution and reflects a novel common one of tumor and cancer.
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Affiliation(s)
- Qingchun Chen
- Computation and Systems Biology, School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing, China
| | - Lin Wang
- Computation and Systems Biology, School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing, China
| | - Minghu Jiang
- Lab of Computational Linguistics, School of Humanities and Social Sciences, Tsinghua University, Beijing, China
| | - Juxiang Huang
- Computation and Systems Biology, School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing, China
| | - Zhenfu Jiang
- Computation and Systems Biology, School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing, China
| | - Haitao Feng
- Dean department, Heilongjiang University of Chinese Medicine, Harbin, China
| | - Zhili Ji
- Department of General Surgery, Beijing Luhe Hospital, Capital Medical University, Beijing, China
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15
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Wiedmeier JE, Ohlrich A, Chu A, Rountree MR, Turker MS. Induction of the long noncoding RNA NBR2 from the bidirectional BRCA1 promoter under hypoxic conditions. Mutat Res 2017; 796:13-19. [PMID: 28249151 DOI: 10.1016/j.mrfmmm.2017.02.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 01/27/2017] [Accepted: 02/09/2017] [Indexed: 06/06/2023]
Abstract
BRCA1 plays an important role in preventing breast cancer and is often silenced or repressed in sporadic cancer. The BRCA1 promoter is bidirectional: it drives transcription of the long non-coding (lnc) NBR2 transcript in the opposite orientation relative to the BRCA1 transcript. Hypoxic conditions repress BRCA1 transcription, but their effect on expression of the NBR2 transcript has not been reported. We used quantitative RT-PCR to measure BRCA1 and NBR2 transcript levels in 0% and 1% oxygen in MCF-7 breast cancer cells and found that NBR2 transcript levels increased as a function of time under hypoxic conditions, whereas BRCA1 mRNA levels were repressed. Hypoxic conditions were ineffective in reducing BRCA1 mRNA in the UACC-3199 breast cancer cell line, which is reported to have an epigenetically silenced BRCA1 promoter, even though appreciable levels of BRCA1 and NBR2 mRNA were detected. Significant recovery back to baseline RNA levels occurred within 48h after the MCF-7 cells were restored to normoxic conditions. We used a construct with the 218bp minimal BRCA1 promoter linked to marker genes to show that this minimal promoter repressed expression bidirectionally under hypoxic conditions, which suggests that the elements necessary for induction of NBR2 are located elsewhere.
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Affiliation(s)
- J Erin Wiedmeier
- University of Utah School of Medicine, Salt Lake City, UT 84132, United States
| | - Anna Ohlrich
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR, 97239, United States
| | - Adrian Chu
- University of Utah School of Medicine, Salt Lake City, UT 84132, United States
| | | | - Mitchell S Turker
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR, 97239, United States; Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR, 97239, United States.
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16
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Haag T, Richter AM, Schneider MB, Jiménez AP, Dammann RH. The dual specificity phosphatase 2 gene is hypermethylated in human cancer and regulated by epigenetic mechanisms. BMC Cancer 2016; 16:49. [PMID: 26833217 PMCID: PMC4736155 DOI: 10.1186/s12885-016-2087-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 01/27/2016] [Indexed: 12/31/2022] Open
Abstract
Background Dual specificity phosphatases are a class of tumor-associated proteins involved in the negative regulation of the MAP kinase pathway. Downregulation of the dual specificity phosphatase 2 (DUSP2) has been reported in cancer. Epigenetic silencing of tumor suppressor genes by abnormal promoter methylation is a frequent mechanism in oncogenesis. It has been shown that the epigenetic factor CTCF is involved in the regulation of tumor suppressor genes. Methods We analyzed the promoter hypermethylation of DUSP2 in human cancer, including primary Merkel cell carcinoma by bisulfite restriction analysis and pyrosequencing. Moreover we analyzed the impact of a DNA methyltransferase inhibitor (5-Aza-dC) and CTCF on the epigenetic regulation of DUSP2 by qRT-PCR, promoter assay, chromatin immuno-precipitation and methylation analysis. Results Here we report a significant tumor-specific hypermethylation of DUSP2 in primary Merkel cell carcinoma (p = 0.05). An increase in methylation of DUSP2 was also found in 17 out of 24 (71 %) cancer cell lines, including skin and lung cancer. Treatment of cancer cells with 5-Aza-dC induced DUSP2 expression by its promoter demethylation, Additionally we observed that CTCF induces DUSP2 expression in cell lines that exhibit silencing of DUSP2. This reactivation was accompanied by increased CTCF binding and demethylation of the DUSP2 promoter. Conclusions Our data show that aberrant epigenetic inactivation of DUSP2 occurs in carcinogenesis and that CTCF is involved in the epigenetic regulation of DUSP2 expression. Electronic supplementary material The online version of this article (doi:10.1186/s12885-016-2087-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Tanja Haag
- Institute for Genetics, Justus-Liebig-University, Heinrich-Buff-Ring 58-62, D-35392, Giessen, Germany.
| | - Antje M Richter
- Institute for Genetics, Justus-Liebig-University, Heinrich-Buff-Ring 58-62, D-35392, Giessen, Germany.
| | - Martin B Schneider
- Institute for Genetics, Justus-Liebig-University, Heinrich-Buff-Ring 58-62, D-35392, Giessen, Germany.
| | - Adriana P Jiménez
- Institute for Genetics, Justus-Liebig-University, Heinrich-Buff-Ring 58-62, D-35392, Giessen, Germany.
| | - Reinhard H Dammann
- Institute for Genetics, Justus-Liebig-University, Heinrich-Buff-Ring 58-62, D-35392, Giessen, Germany. .,Universities of Giessen and Marburg Lung Center, 35392, Giessen, Germany.
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17
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Vad-Nielsen J, Nielsen AL. Beyond the histone tale: HP1α deregulation in breast cancer epigenetics. Cancer Biol Ther 2015; 16:189-200. [PMID: 25588111 DOI: 10.1080/15384047.2014.1001277] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Heterochromatin protein 1α (HP1α) encoded from the CBX5-gene is an evolutionary conserved protein that binds histone H3 di- or tri-methylated at position lysine 9 (H3K9me2/3), a hallmark for heterochromatin, and has an essential role in forming higher order chromatin structures. HP1α has diverse functions in heterochromatin formation, gene regulation, and mitotic progression, and forms complex networks of gene, RNA, and protein interactions. Emerging evidence has shown that HP1α serves a unique biological role in breast cancer related processes and in particular for epigenetic control mechanisms involved in aberrant cell proliferation and metastasis. However, how HP1α deregulation plays dual mechanistic functions for cancer cell proliferation and metastasis suppression and the underlying cellular mechanisms are not yet comprehensively described. In this paper we provide an overview of the role of HP1α as a new sight of epigenetics in proliferation and metastasis of human breast cancer. This highlights the importance of addressing HP1α in breast cancer diagnostics and therapeutics.
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Key Words
- CBX, chromobox homolog
- CD, chromo domain
- CSC, cancer stem cells
- CSD, cromo shadow domain
- CTE, C-terminal extension
- DNMT, DNA-methyltransferase
- EMT, epithelial-to-mesenchymal transition
- HDMT, histone demethylase
- HMT, histone methyltransferase
- HP1, heterochromatin protein 1
- NTE, N-terminal extension
- PEV, position effect variegation
- SOMU, sumoylation
- TGS, transcriptional gene silencing
- TSS, transcriptional start site
- bp, base pair
- breast-cancer, metastasis
- chromatin
- epigenetics
- histone-modifications
- invasion
- mitosis
- proliferation
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18
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Boukerroucha M, Josse C, Segers K, El-Guendi S, Frères P, Jerusalem G, Bours V. BRCA1 germline mutation and glioblastoma development: report of cases. BMC Cancer 2015; 15:181. [PMID: 25880076 PMCID: PMC4377178 DOI: 10.1186/s12885-015-1205-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Accepted: 03/17/2015] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Germline mutations in breast cancer susceptibility gene 1 (BRCA1) increase the risk of breast and ovarian cancers. However, no association between BRCA1 germline mutation and glioblastoma malignancy has ever been highlighted. Here we report two cases of BRCA1 mutated patients who developed a glioblastoma multiform (GBM). CASES PRESENTATION Two patients diagnosed with triple negative breast cancer (TNBC) were screened for BRCA1 germline mutation. They both carried a pathogenic mutation introducing a premature STOP codon in the exon 11 of the BRCA1 gene. Few years later, both patients developed a glioblastoma and a second breast cancer. In an attempt to clarify the role played by a mutated BRCA1 allele in the GBM development, we investigated the BRCA1 mRNA and protein expression in breast and glioblastoma tumours for both patients. The promoter methylation status of this gene was also tested by methylation specific PCR as BRCA1 expression is also known to be lost by this mechanism in some sporadic breast cancers. CONCLUSION Our data show that BRCA1 expression is maintained in glioblastoma at the protein and the mRNA levels, suggesting that loss of heterozygosity (LOH) did not occur in these cases. The protein expression is tenfold higher in the glioblastoma of patient 1 than in her first breast carcinoma, and twice higher in patient 2. In agreement with the high protein expression level in the GBM, BRCA1 promoter methylation was not observed in these tumours. In these two cases, despite of a BRCA1 pathogenic germline mutation, the tumour-suppressor protein expression is maintained in GBM, suggesting that the BRCA1 mutation is not instrumental for the GBM development.
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Affiliation(s)
- Meriem Boukerroucha
- University of Liège, GIGA-Cancer Research, Human Genetics Unit, Liège, Belgium.
| | - Claire Josse
- University of Liège, GIGA-Cancer Research, Human Genetics Unit, Liège, Belgium. .,Division of Medical Oncology, Liège University and CHU Sart Tilman Liège, Liège, Belgium.
| | - Karin Segers
- Human Genetics Department, Liège University Hospital, Liège, Belgium.
| | - Sonia El-Guendi
- University of Liège, GIGA-Cancer Research, Human Genetics Unit, Liège, Belgium.
| | - Pierre Frères
- Division of Medical Oncology, Liège University and CHU Sart Tilman Liège, Liège, Belgium.
| | - Guy Jerusalem
- Division of Medical Oncology, Liège University and CHU Sart Tilman Liège, Liège, Belgium.
| | - Vincent Bours
- University of Liège, GIGA-Cancer Research, Human Genetics Unit, Liège, Belgium. .,Human Genetics Department, Liège University Hospital, Liège, Belgium.
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19
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Xu J, Chen Y, Huo D, Khramtsov A, Khramtsova G, Zhang C, Goss KH, Olopade OI. β-catenin regulates c-Myc and CDKN1A expression in breast cancer cells. Mol Carcinog 2015; 55:431-9. [PMID: 25663530 DOI: 10.1002/mc.22292] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 12/17/2014] [Accepted: 12/30/2014] [Indexed: 02/01/2023]
Abstract
We previously reported that the Wnt pathway is preferentially activated in basal-like breast cancer. However, the mechanisms by which the Wnt pathway regulates down-stream targets in basal-like breast cancer, and the biological significance of this regulation, are poorly understood. In this study, we found that c-Myc is highly expressed in the basal-like subtype by microarray analyses and immunohistochemical staining. After silencing β-catenin using siRNA, c-Myc expression was decreased in non-basal-like breast cancer cells. In contrast, c-Myc mRNA and protein expression were up-regulated in the basal-like breast cancer cell lines. Decreased c-Myc promoter activity was observed after inhibiting β-catenin by siRNA in non-basal-like breast cancer cells; however, inhibition of β-catenin or over-expression of dominant-negative LEF1 had no effect on c-Myc promoter activity in basal-like breast cancer cell lines. In addition, CDKN1A mRNA and p21 protein expression were significantly increased in all breast cancer cell lines upon β-catenin silencing. Interestingly, inhibiting β-catenin expression alone did not induce apoptosis in breast cancer cell lines despite c-Myc regulation, but we observed a modest increase of cells in the G1 phase of the cell cycle and decrease of cells in S phase upon β-catenin silencing. Our findings suggest that the regulation of c-Myc in breast cancer cells is dependent on the molecular subtype, and that β-catenin-mediated regulation of c-Myc and p21 may control the balance of cell death and proliferation in breast cancer.
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Affiliation(s)
- Jinhua Xu
- Section of Hematology/Oncology, Department of Medicine, University of Chicago, Chicago,, Illinois.,School of Medicine, Jianghan University, Wuhan, Hubei, P. R. China
| | - Yinghua Chen
- Section of Hematology/Oncology, Department of Medicine, University of Chicago, Chicago,, Illinois
| | - Dezheng Huo
- Department of Public Health Sciences, University of Chicago, Chicago, Illinois
| | - Andrey Khramtsov
- Section of Hematology/Oncology, Department of Medicine, University of Chicago, Chicago,, Illinois
| | - Galina Khramtsova
- Section of Hematology/Oncology, Department of Medicine, University of Chicago, Chicago,, Illinois
| | - Chunling Zhang
- Section of Hematology/Oncology, Department of Medicine, University of Chicago, Chicago,, Illinois
| | - Kathleen H Goss
- University of Chicago Comprehensive Cancer Center, University of Chicago, Chicago, Illinois
| | - Olufunmilayo I Olopade
- Section of Hematology/Oncology, Department of Medicine, University of Chicago, Chicago,, Illinois.,Department of Human Genetics, University of Chicago, Chicago, Illinois
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20
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Xu J, Prosperi JR, Choudhury N, Olopade OI, Goss KH. β-Catenin is required for the tumorigenic behavior of triple-negative breast cancer cells. PLoS One 2015; 10:e0117097. [PMID: 25658419 PMCID: PMC4319896 DOI: 10.1371/journal.pone.0117097] [Citation(s) in RCA: 127] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 12/18/2014] [Indexed: 01/16/2023] Open
Abstract
Our previous data illustrated that activation of the canonical Wnt signaling pathway was enriched in triple-negative breast cancer and associated with reduced overall survival in all patients. To determine whether Wnt signaling may be a promising therapeutic target for triple-negative breast cancer, we investigated whether β-catenin was necessary for tumorigenic behaviors in vivo and in vitro. β-catenin expression level was significantly reduced in two human triple-negative breast cancer cell lines, MDA-MB-231 and HCC38, using lentiviral delivery of β-catenin-specific small hairpin RNAs (shRNAs). Upon implantation of the cells in the mammary fat pad of immunocompromised mice, we found that β-catenin shRNA HCC38 cells formed markedly smaller tumors than control cells and grew much more slowly. In in vitro assays, β-catenin silencing significantly reduced the percentage of Aldefluor-positive cells, a read-out of the stem-like cell population, as well as the expression of stem cell-related target genes including Bmi-1 and c-Myc. β-catenin-knockdown cells were also significantly impaired in their ability to migrate in wound-filling assays and form anchorage-independent colonies in soft agar. β-catenin-knockdown cells were more sensitive to chemotherapeutic agents doxorubicin and cisplatin. Collectively, these data suggest that β-catenin is required for triple-negative breast cancer development by controlling numerous tumor-associated properties, such as migration, stemness, anchorage-independent growth and chemosensitivity.
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Affiliation(s)
- Jinhua Xu
- Department of Surgery and Comprehensive Cancer Center, University of Chicago, Chicago, IL 60637, United States of America; Department of Medicine, University of Chicago, Chicago, IL 60637, United States of America; School of Medicine, Jianghan University, Wuhan, Hubei 430056, P.R. China
| | - Jenifer R Prosperi
- Department of Surgery and Comprehensive Cancer Center, University of Chicago, Chicago, IL 60637, United States of America; Department of Biochemistry and Molecular Biology, Indiana University School of Medicine-South Bend, South Bend, IN 46530, United States of America
| | - Noura Choudhury
- Department of Surgery and Comprehensive Cancer Center, University of Chicago, Chicago, IL 60637, United States of America
| | - Olufunmilayo I Olopade
- Department of Medicine, University of Chicago, Chicago, IL 60637, United States of America
| | - Kathleen H Goss
- Department of Surgery and Comprehensive Cancer Center, University of Chicago, Chicago, IL 60637, United States of America
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Hill SJ, Rolland T, Adelmant G, Xia X, Owen MS, Dricot A, Zack TI, Sahni N, Jacob Y, Hao T, McKinney KM, Clark AP, Reyon D, Tsai SQ, Joung JK, Beroukhim R, Marto JA, Vidal M, Gaudet S, Hill DE, Livingston DM. Systematic screening reveals a role for BRCA1 in the response to transcription-associated DNA damage. Genes Dev 2014; 28:1957-75. [PMID: 25184681 PMCID: PMC4197947 DOI: 10.1101/gad.241620.114] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
BRCA1 is a breast and ovarian tumor suppressor. Given its numerous incompletely understood functions and the possibility that more exist, we performed complementary systematic screens in search of new BRCA1 protein-interacting partners. New BRCA1 functions and/or a better understanding of existing ones were sought. Among the new interacting proteins identified, genetic interactions were detected between BRCA1 and four of the interactors: TONSL, SETX, TCEANC, and TCEA2. Genetic interactions were also detected between BRCA1 and certain interactors of TONSL, including both members of the FACT complex. From these results, a new BRCA1 function in the response to transcription-associated DNA damage was detected. Specifically, new roles for BRCA1 in the restart of transcription after UV damage and in preventing or repairing damage caused by stabilized R loops were identified. These roles are likely carried out together with some of the newly identified interactors. This new function may be important in BRCA1 tumor suppression, since the expression of several interactors, including some of the above-noted transcription proteins, is repeatedly aberrant in both breast and ovarian cancers.
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Affiliation(s)
- Sarah J Hill
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Thomas Rolland
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA; Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA
| | - Guillaume Adelmant
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA; Blais Proteomics Center, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA
| | - Xianfang Xia
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA; Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA
| | - Matthew S Owen
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA; Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA
| | - Amélie Dricot
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA; Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA
| | - Travis I Zack
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA; The Broad Institute, Cambridge, Massachusetts 02142, USA
| | - Nidhi Sahni
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA; Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA
| | - Yves Jacob
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA; Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA; Département de Virologie, Unité de Génétique Moléculaire des Virus à ARN, Institut Pasteur, F-75015 Paris, France; UMR3569, Centre National de la Recherche Scientifique, F-75015 Paris, France; Unité de Génétique Moléculaire des Virus à ARN, Université Paris Diderot, F-75015 Paris, France
| | - Tong Hao
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA; Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA
| | - Kristine M McKinney
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Allison P Clark
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Deepak Reyon
- Molecular Pathology Unit, Center for Computational and Integrative Biology, Center for Cancer Research, Massachusetts General Hospital, Charlestown, Massachusetts 02129, USA; Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Shengdar Q Tsai
- Molecular Pathology Unit, Center for Computational and Integrative Biology, Center for Cancer Research, Massachusetts General Hospital, Charlestown, Massachusetts 02129, USA; Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - J Keith Joung
- Molecular Pathology Unit, Center for Computational and Integrative Biology, Center for Cancer Research, Massachusetts General Hospital, Charlestown, Massachusetts 02129, USA; Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Rameen Beroukhim
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA; The Broad Institute, Cambridge, Massachusetts 02142, USA; Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA
| | - Jarrod A Marto
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA; Blais Proteomics Center, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA
| | - Marc Vidal
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA; Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA
| | - Suzanne Gaudet
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA; Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA
| | - David E Hill
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA; Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA
| | - David M Livingston
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA;
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22
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Tang H, Liu P, Yang L, Xie X, Ye F, Wu M, Liu X, Chen B, Zhang L, Xie X. miR-185 Suppresses Tumor Proliferation by Directly Targeting E2F6 and DNMT1 and Indirectly Upregulating BRCA1 in Triple-Negative Breast Cancer. Mol Cancer Ther 2014; 13:3185-97. [DOI: 10.1158/1535-7163.mct-14-0243] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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23
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Schröder-Heurich B, Bogdanova N, Wieland B, Xie X, Noskowicz M, Park-Simon TW, Hillemanns P, Christiansen H, Dörk T. Functional deficiency of NBN, the Nijmegen breakage syndrome protein, in a p.R215W mutant breast cancer cell line. BMC Cancer 2014; 14:434. [PMID: 24928521 PMCID: PMC4085727 DOI: 10.1186/1471-2407-14-434] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 05/26/2014] [Indexed: 12/17/2022] Open
Abstract
Background Mutations in NBN, the gene for Nijmegen Breakage Syndrome (NBS), are thought to predispose women to developing breast cancer, but a breast cancer cell line containing mutations in NBN has not yet been described. The p.R215W missense mutation occurs at sub-polymorphic frequencies in several populations. We aimed to investigate its functional impact in breast cancer cells from a carrier of this NBN mutation. Methods Breast cancer cell lines were screened by immunoblotting for NBN protein levels, and the NBN coding region was sequenced for mutation analysis. Radiosensitivity assays and functional studies were performed through immunocytochemistry and immunoblotting, and flow cytometry was employed to assess cell cycle progression. Impedance measurements were used to study the consequences of PARP1 inhibition. Statistical comparisons between cell lines were performed using t-tests. Results HCC1395 breast cancer cells exhibited reduced NBN protein levels. Direct sequencing identified the NBN p.R215W mutation in the hemizygous state, in addition to a truncation in BRCA1. Mutations in both genes were already present in the heterozygous state in the patient’s germline. HCC1395 cells were highly radiosensitive, susceptible to apoptosis and were deficient in the formation of NBN foci. There was also evidence for some impairment in the formation of γH2AX, MDC1, and 53BP1 foci after irradiation; these foci appeared smaller and irregular compared with repair foci in wild-type cells, although ATM signalling was largely unaffected. In line with their deficiency in NBN and BRCA1, HCC1395 cells were particularly sensitive to PARP1 inhibition. Conclusion Our results indicate that the p.R215W mutation in the HCC1395 breast cancer cell line impairs NBN function, making this cell line a potentially useful cellular model for studying defective NBN protein within a mutant BRCA1 background.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Thilo Dörk
- Clinics of Obstetrics and Gynaecology, Hannover Medical School, Carl-Neuberg Straße 1, D-30625 Hannover, Germany.
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24
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Differential methylation relative to breast cancer subtype and matched normal tissue reveals distinct patterns. Breast Cancer Res Treat 2013; 142:365-80. [PMID: 24212716 PMCID: PMC3832780 DOI: 10.1007/s10549-013-2738-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 10/12/2013] [Indexed: 11/17/2022]
Abstract
Due to the heterogeneous nature of breast cancer and the widespread use of single-gene studies, there is limited knowledge of multi-gene, locus-specific DNA methylation patterns in relation to molecular subtype and clinical features. We, therefore, quantified DNA methylation of 70 candidate gene loci in 140 breast tumors and matched normal tissues and determined associations with gene expression and tumor subtype. Using Sequenom’s EpiTYPER platform, approximately 1,200 CpGs were interrogated and revealed six DNA methylation patterns in breast tumors relative to matched normal tissue. Differential methylation of several gene loci was observed within all molecular subtypes, while other patterns were subtype-dependent. Methylation of numerous gene loci was inversely correlated with gene expression, and in some cases, this correlation was only observed within specific breast tumor subtypes. Our findings were validated on a larger set of tumors and matched adjacent normal tissue from The Cancer Genome Atlas dataset, which utilized methylation data derived from both Illumina Infinium 27 and 450 k arrays. These findings highlight the need to control for subtype when interpreting DNA methylation results, and the importance of interrogating multiple CpGs across varied gene regions.
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25
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Wang Q, Li J, Yang X, Sun H, Gao S, Zhu H, Wu J, Jin W. Nrf2 is associated with the regulation of basal transcription activity of the BRCA1 gene. Acta Biochim Biophys Sin (Shanghai) 2013; 45:179-87. [PMID: 23353771 DOI: 10.1093/abbs/gmt001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
BRCA1 is closely related to the pathogenesis of breast cancer. The activity of BRCA1 promoter is regulated by transcriptional factors. The transcription factor Nrf2 (Nuclear factor-erythroid-2p45-related factor 2) is a potent transcriptional activator and plays a central role in inducible expression of many cytoprotective genes. In this report, we found that over-expression of Nrf2 stimulated BRCA1 expression, knockdown of Nrf2 attenuated BRCA1 expression. Nrf2 also interacted with CBP and p300 to form an active transcription complex, which could bind to the ARE (antioxidant response element) site on the BRCA1 promoter and activate its transcription by inducing histone acetylation. Our finding could lead to a better understanding of the development of breast cancer.
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Affiliation(s)
- Qiaoqiao Wang
- Department of Oncology, Department of Breast Surgery, Breast Cancer Institute, Shanghai Cancer Center, Shanghai Medical College, Fudan University, Shanghai 200032, China
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26
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Popova T, Manié E, Rieunier G, Caux-Moncoutier V, Tirapo C, Dubois T, Delattre O, Sigal-Zafrani B, Bollet M, Longy M, Houdayer C, Sastre-Garau X, Vincent-Salomon A, Stoppa-Lyonnet D, Stern MH. Ploidy and large-scale genomic instability consistently identify basal-like breast carcinomas with BRCA1/2 inactivation. Cancer Res 2012; 72:5454-62. [PMID: 22933060 DOI: 10.1158/0008-5472.can-12-1470] [Citation(s) in RCA: 466] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BRCA1 inactivation is a frequent event in basal-like breast carcinomas (BLC). However, BRCA1 can be inactivated by multiple mechanisms and determining its status is not a trivial issue. As an alternate approach, we profiled 65 BLC cases using single-nucleotide polymorphism arrays to define a signature of BRCA1-associated genomic instability. Large-scale state transitions (LST), defined as chromosomal break between adjacent regions of at least 10 Mb, were found to be a robust indicator of BRCA1 status in this setting. Two major ploidy-specific cutoffs in LST distributions were sufficient to distinguish highly rearranged BLCs with 85% of proven BRCA1-inactivated cases from less rearranged BLCs devoid of proven BRCA1-inactivated cases. The genomic signature we defined was validated in a second independent series of 55 primary BLC cases and 17 BLC-derived tumor cell lines. High numbers of LSTs resembling BRCA1-inactivated BLC were observed in 4 primary BLC cases and 2 BLC cell lines that harbored BRCA2 mutations. Overall, the genomic signature we defined predicted BRCA1/2 inactivation in BLCs with 100% sensitivity and 90% specificity (97% accuracy). This assay may ease the challenge of selecting patients for genetic testing or recruitment to clinical trials of novel emerging therapies that target DNA repair deficiencies in cancer.
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Affiliation(s)
- Tatiana Popova
- Centre de Recherche, University Paris-Descartes, Paris, France
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27
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Gaykalova D, Vatapalli R, Glazer CA, Bhan S, Shao C, Sidransky D, Ha PK, Califano JA. Dose-dependent activation of putative oncogene SBSN by BORIS. PLoS One 2012; 7:e40389. [PMID: 22792300 PMCID: PMC3390376 DOI: 10.1371/journal.pone.0040389] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 06/06/2012] [Indexed: 11/18/2022] Open
Abstract
Testis-specific transcription factor BORIS (Brother of the Regulator of Imprinted Sites), a paralog and proposed functional antagonist of the widely expressed CTCF, is abnormally expressed in multiple tumor types and has been implicated in the epigenetic activation of cancer-testis antigens (CTAs). We have reported previously that suprabasin (SBSN), whose expression is restricted to the epidermis, is epigenetically derepressed in lung cancer. In this work, we establish that SBSN is a novel non-CTA target of BORIS epigenetic regulation. With the use of a doxycycline-inducible BORIS expressing vector, we demonstrate that relative BORIS dosage is critical for SBSN activation. At lower concentrations, BORIS induces demethylation of the SBSN CpG island and disruption and activation of chromatin around the SBSN transcription start site (TSS), resulting in a 35-fold increase in SBSN expression in the H358 human lung cancer cell line. Interestingly, increasing BORIS concentrations leads to a subsequent reduction in SBSN expression via chromatin repression. In a similar manner, increase in BORIS concentrations leads to eventual decrease of cell growth and colony formation. This is the first report demonstrating that different amount of BORIS defines its varied effects on the expression of a target gene via chromatin structure reorganization.
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Affiliation(s)
- Daria Gaykalova
- Department of Otolaryngology–Head and Neck Surgery, Johns Hopkins Medical Institutions, Baltimore, Maryland, United States of America
| | - Rajita Vatapalli
- Department of Otolaryngology–Head and Neck Surgery, Johns Hopkins Medical Institutions, Baltimore, Maryland, United States of America
| | - Chad A. Glazer
- Department of Otolaryngology–Head and Neck Surgery, Johns Hopkins Medical Institutions, Baltimore, Maryland, United States of America
| | - Sheetal Bhan
- Department of Otolaryngology–Head and Neck Surgery, Johns Hopkins Medical Institutions, Baltimore, Maryland, United States of America
| | - Chunbo Shao
- Department of Otolaryngology–Head and Neck Surgery, Johns Hopkins Medical Institutions, Baltimore, Maryland, United States of America
| | - David Sidransky
- Department of Otolaryngology–Head and Neck Surgery, Johns Hopkins Medical Institutions, Baltimore, Maryland, United States of America
- Department of Oncology, Johns Hopkins Medical Institutions, Baltimore, Maryland, United States of America
- Milton J. Dance Head and Neck Center, Greater Baltimore Medical Center, Baltimore, Maryland, United States of America
| | - Patrick K. Ha
- Department of Otolaryngology–Head and Neck Surgery, Johns Hopkins Medical Institutions, Baltimore, Maryland, United States of America
- Milton J. Dance Head and Neck Center, Greater Baltimore Medical Center, Baltimore, Maryland, United States of America
| | - Joseph A. Califano
- Department of Otolaryngology–Head and Neck Surgery, Johns Hopkins Medical Institutions, Baltimore, Maryland, United States of America
- Department of Oncology, Johns Hopkins Medical Institutions, Baltimore, Maryland, United States of America
- Milton J. Dance Head and Neck Center, Greater Baltimore Medical Center, Baltimore, Maryland, United States of America
- * E-mail:
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Wakano C, Byun JS, Di LJ, Gardner K. The dual lives of bidirectional promoters. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1819:688-93. [PMID: 22366276 PMCID: PMC3371153 DOI: 10.1016/j.bbagrm.2012.02.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 02/06/2012] [Accepted: 02/09/2012] [Indexed: 12/12/2022]
Abstract
The sequencing of the human genome led to many insights into gene organization and structure. One interesting observation was the high frequency of bidirectional promoters characterized by two protein encoding genes whose promoters are arranged in a divergent or "head-to-head" configuration with less than 2000 base pairs of intervening sequence. Computational estimates published by various groups indicate that nearly 10% of the coding gene promoters are arranged in such a manner and the extent of this bias is a unique feature of mammalian genomes. Moreover, as a class, head-to-head promoters appear to be enriched in specific categories of gene function. Here we review the structure, composition, genomic properties and functional classifications of genes controlled by bidirectional promoters and explore the biological implication of these features. This article is part of a Special Issue entitled: Chromatin in time and space.
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Affiliation(s)
- Clay Wakano
- Genetics Branch, National Cancer Institute, Bethesda, Maryland 20892, USA
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, Bethesda, Maryland 20892, USA
| | - Jung S. Byun
- Genetics Branch, National Cancer Institute, Bethesda, Maryland 20892, USA
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, Bethesda, Maryland 20892, USA
| | - Li-Jun Di
- Genetics Branch, National Cancer Institute, Bethesda, Maryland 20892, USA
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, Bethesda, Maryland 20892, USA
| | - Kevin Gardner
- Genetics Branch, National Cancer Institute, Bethesda, Maryland 20892, USA
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, Bethesda, Maryland 20892, USA
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Cerne JZ, Zong L, Jelinek J, Hilsenbeck SG, Wang T, Oesterreich S, McGuire SE. BRCA1 promoter methylation status does not predict response to tamoxifen in sporadic breast cancer patients. Breast Cancer Res Treat 2012; 135:135-43. [PMID: 22706629 DOI: 10.1007/s10549-012-2117-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Accepted: 05/26/2012] [Indexed: 12/30/2022]
Abstract
The purpose of this study is to investigate whether BRCA1 promoter methylation is associated with poorer outcome in sporadic breast cancer cases treated with tamoxifen. BRCA1 promoter methylation was determined by bisulfite pyrosequencing in two groups of sporadic breast cancer patients, systemically untreated (N = 497) and treated with adjuvant tamoxifen (N = 497). Associations of BRCA1 promoter methylation with clinopathological characteristics and the effect of BRCA1 promoter methylation on time to first recurrence (TTR) and overall survival (OS) were examined. No significant differences were observed between BRCA1 promoter methylation and clinopathological characteristics in untreated and tamoxifen-treated groups. Cut point analysis did not find any promising cut point for BRCA1 promoter methylation that would differentially influence TTR and OS in untreated and tamoxifen-treated group. Using the median (2.53 %) and an arbitrary value of 10 % as a cut point for methylation, we still found no significant effect of BRCA1 promoter methylation on TTR and OS in untreated and tamoxifen-treated group. Despite data suggesting that BRCA1 levels impact estrogen receptor response to tamoxifen, our results indicate that BRCA1 promoter methylation is not associated with poorer outcome in sporadic breast cancer cases treated with tamoxifen.
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Affiliation(s)
- Jasmina Z Cerne
- Department of Molecular & Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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30
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Abstract
CTCF is an evolutionary conserved and ubiquitously expressed protein that binds thousands of sites in the human genome. Ectopic expression of CTCF in various normal and tumoral human cell lines inhibits cell division and clonogenicity, with the consequence to consider CTCF a potential tumor-suppressor factor. In this review article, we focused on the molecular mechanisms engaged by CTCF to modulate the expression of several key-regulators of differentiation, cellular senescence, cell cycle control and progression, whose expression is frequently altered in tumors. Moreover, we discussed common features of CTCF at each tumor-related DNA-binding sequence, such as protein-partners, post-translational modifications, and distinctive epigenetic marks establishment. The investigation of the molecular mechanisms engaged by CTCF to modulate tumor-related genes emphasizes the cell-type dependency of its tumor suppressor role. Indeed, the ability of CTCF to bind their promoters strictly depends by cell-type features as DNA methylation, BORIS-binding and post-translational modifications as PARYlation.
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Affiliation(s)
- Francesco Paolo Fiorentino
- Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, Department of Biology, College of Science and Technology, Temple University, Philadelphia, Pennsylvania 19122, USA
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Abstract
Chromatin insulators are DNA-protein complexes with broad functions in nuclear biology. Based on the ability of insulator proteins to interact with each other, it was originally found that insulators form loops that bring together distant regions of the genome. Data from genome-wide localization studies indicate that insulator proteins can be present in intergenic regions as well as at the 5', introns or 3' of genes, suggesting a variety of roles for insulator loops in chromosome biology. Recent results suggest that insulators mediate intra- and interchromosomal interactions to affect transcription, imprinting, and recombination. Cells have developed mechanisms to control insulator activity by recruiting specialized proteins or by covalent modification of core components. It is then possible that insulator-mediated interactions set up cell-specific blueprints of nuclear organization that may contribute to the establishment of different patterns of gene expression during cell differentiation and development. As a consequence, disruption of insulator activity could result in the development of cancer or other disease states.
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Affiliation(s)
- Jingping Yang
- Department of Biology, Emory University, Atlanta, GA, USA
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32
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Chen Y, Xu J, Borowicz S, Collins C, Huo D, Olopade OI. c-Myc activates BRCA1 gene expression through distal promoter elements in breast cancer cells. BMC Cancer 2011; 11:246. [PMID: 21668996 PMCID: PMC3141769 DOI: 10.1186/1471-2407-11-246] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Accepted: 06/13/2011] [Indexed: 12/26/2022] Open
Abstract
Background The BRCA1 gene plays an important role in the maintenance of genomic stability. BRCA1 inactivation contributes to breast cancer tumorigenesis. An increasing number of transcription factors have been shown to regulate BRCA1 expression. c-Myc can act as a transcriptional activator, regulating up to 15% of all genes in the human genome and results from a high throughput screen suggest that BRCA1 is one of its targets. In this report, we used cultured breast cancer cells to examine the mechanisms of transcriptional activation of BRCA1 by c-Myc. Methods c-Myc was depleted using c-Myc-specific siRNAs in cultured breast cancer cells. BRCA1 mRNA expression and BRCA1 protein expression were determined by quantitative RT-PCR and western blot, respectively and BRCA1 promoter activities were examined under these conditions. DNA sequence analysis was conducted to search for high similarity to E boxes in the BRCA1 promoter region. The association of c-Myc with the BRCA1 promoter in vivo was tested by a chromatin immunoprecipitation assay. We investigated the function of the c-Myc binding site in the BRCA1 promoter region by a promoter assay with nucleotide substitutions in the putative E boxes. BRCA1-dependent DNA repair activities were measured by a GFP-reporter assay. Results Depletion of c-Myc was found to be correlated with reduced expression levels of BRCA1 mRNA and BRCA1 protein. Depletion of c-Myc decreased BRCA1 promoter activity, while ectopically expressed c-Myc increased BRCA1 promoter activity. In the distal BRCA1 promoter, DNA sequence analysis revealed two tandem clusters with high similarity, and each cluster contained a possible c-Myc binding site. c-Myc bound to these regions in vivo. Nucleotide substitutions in the c-Myc binding sites in these regions abrogated c-Myc-dependent promoter activation. Furthermore, breast cancer cells with reduced BRCA1 expression due to depletion of c-Myc exhibited impaired DNA repair activity. Conclusions The distal BRCA1 promoter region is associated with c-Myc and contributes to BRCA1 gene activation.
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Affiliation(s)
- Yinghua Chen
- Center for Clinical Cancer Genetics and Global Health, Department of Medicine, University of Chicago, Chicago, IL, USA
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Amouyal M. Gene insulation. Part II: natural strategies in vertebrates. Biochem Cell Biol 2011; 88:885-98. [PMID: 21102651 DOI: 10.1139/o10-111] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The way a gene is insulated from its genomic environment in vertebrates is not basically different from what is observed in yeast and Drosophila (preceding article in this issue). If the formation of a looped chromatin domain, whether generated by attachment to the nuclear matrix or not, has become a classic way to confine an enhancer to a specific genomic domain and to coordinate, sequentially or simultaneously, gene expression in a given program, its role has been extended to new networks of genes or regulators within the same gene. A wider definition of the bases of the chromatin loops (nonchromosomal nuclear structures or genomic interacting elements) is also available. However, whereas insulation in Drosophila is due to a variety of proteins, in vertebrates insulators are still practically limited to CTCF (the CCCTC-binding factor), which appears in all cases to be the linchpin of an architecture that structures the assembly of DNA-protein interactions for gene regulation. As in yeast and Drosophila, the economy of means is the rule and the same unexpected diversion of known transcription elements (active or poised RNA polymerases, TFIIIC elements out of tRNA genes, permanent histone replacement) is observed, with variants peculiar to CTCF. Thus, besides structuring DNA looping, CTCF is a barrier to DNA methylation or interferes with all sorts of transcription processes, such as that generating heterochromatin.
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van Roon EHJ, de Miranda NFCC, van Nieuwenhuizen MP, de Meijer EJ, van Puijenbroek M, Yan PS, Huang THM, van Wezel T, Morreau H, Boer JM. Tumour-specific methylation of PTPRG intron 1 locus in sporadic and Lynch syndrome colorectal cancer. Eur J Hum Genet 2010; 19:307-12. [PMID: 21150880 DOI: 10.1038/ejhg.2010.187] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
DNA methylation is a hallmark in a subset of right-sided colorectal cancers. Methylation-based screening may improve prevention and survival rate for this type of cancer, which is often clinically asymptomatic in the early stages. We aimed to discover prognostic or diagnostic biomarkers for colon cancer by comparing DNA methylation profiles of right-sided colon tumours and paired normal colon mucosa using an 8.5 k CpG island microarray. We identified a diagnostic CpG-rich region, located in the first intron of the protein-tyrosine phosphatase gamma gene (PTPRG) gene, with altered methylation already in the adenoma stage, that is, before the carcinoma transition. Validation of this region in an additional cohort of 103 sporadic colorectal tumours and 58 paired normal mucosa tissue samples showed 94% sensitivity and 96% specificity. Interestingly, comparable results were obtained when screening a cohort of Lynch syndrome-associated cancers. Functional studies showed that PTPRG intron 1 methylation did not directly affect PTPRG expression, however, the methylated region overlapped with a binding site of the insulator protein CTCF. Chromatin immunoprecipitation (ChIP) showed that methylation of the locus was associated with absence of CTCF binding. Methylation-associated changes in CTCF binding to PTPRG intron 1 could have implications on tumour gene expression by enhancer blocking, chromosome loop formation or abrogation of its insulator function. The high sensitivity and specificity for the PTPRG intron 1 methylation in both sporadic and hereditary colon cancers support biomarker potential for early detection of colon cancer.
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Affiliation(s)
- Eddy H J van Roon
- Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands
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Jin W, Liu Y, Chen L, Zhu H, Di GH, Ling H, Wu J, Shao ZM. Involvement of MyoD and c-myb in regulation of basal and estrogen-induced transcription activity of the BRCA1 gene. Breast Cancer Res Treat 2010; 125:699-713. [PMID: 20364308 DOI: 10.1007/s10549-010-0876-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Accepted: 03/25/2010] [Indexed: 01/12/2023]
Abstract
BRCA1 is closely related to the pathogenesis of breast cancer, BRCA1 mRNA is reduced in sporadic breast cancer cells despite the lack of mutations. In the present report, we find that MyoD expression and BRCA1 expression is correlated in sporadic breast tumors, overexpression of MyoD and c-myb stimulates BRCA1 expression, knockdown of MyoD and c-myb attenuates BRCA1 expression and attenuates the ability of BRCA1 to protect cells against hydrogen peroxide. MyoD and c-myb interact with p300 and PCAF, forming activating transcriptional complexes which bind to E-box and c-myb sites on the BRCA1 promoter and activate its transcription by inducing histone acetylation. Regulation of BRCA1 expression by MyoD and c-myb complexes may be part of an integral signaling pathway that determines and explains breast cancer susceptibility. Detection expression status of the various proteins in these complexes may predispose to the onset of sporadic breast cancer.
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Affiliation(s)
- Wei Jin
- Department of Breast Surgery, Breast Cancer Institute, Cancer Hospital/Cancer Institute, Department of Oncology, Shanghai Medical College, Fudan University, 270 Dong An Road Road, Shanghai, 200032, People's Republic of China
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