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Qi Y, Li L, Wei Y, Ma F. PP2A as a potential therapeutic target for breast cancer: Current insights and future perspectives. Biomed Pharmacother 2024; 173:116398. [PMID: 38458011 DOI: 10.1016/j.biopha.2024.116398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2023] [Revised: 02/28/2024] [Accepted: 03/06/2024] [Indexed: 03/10/2024] Open
Abstract
Breast cancer has become the most prevalent malignancy worldwide; however, therapeutic efficacy is far from satisfactory. To alleviate the burden of this disease, it is imperative to discover novel mechanisms and treatment strategies. Protein phosphatase 2 A (PP2A) comprises a family of mammalian serine/threonine phosphatases that regulate many cellular processes. PP2A is dysregulated in several human diseases, including oncological pathologies, and plays a pivotal role in the initiation and progression of tumours. The role of PP2A as a tumour suppressor has been extensively studied, and its regulation can serve as a target for anticancer therapy. Recent studies have shown that PP2A is a tumour promotor. PP2A-mediated anticancer therapy may involve two opposing mechanisms: activation and inhibition. In general, the contradictory roles of PP2A should not be overlooked, and more work is needed to determine the molecular mechanism by which PP2A affects in tumours. In this review, the literature on the role of PP2A in tumours, especially in breast cancer, was analysed. This review describes relevant targets of breast cancer, such as cell cycle control, DNA damage responses, epidermal growth factor receptor, immune modulation and cell death resistance, which may lead to effective therapeutic strategies or influence drug development in breast cancer.
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Affiliation(s)
- Yalong Qi
- Department of Medical Oncology, National Cancer Center, National Clinical Research Center for Cancer, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Chaoyang District, Pan jia yuan nan Road 17, Beijing 100021, China
| | - Lixi Li
- Department of Medical Oncology, National Cancer Center, National Clinical Research Center for Cancer, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Chaoyang District, Pan jia yuan nan Road 17, Beijing 100021, China
| | - Yuhan Wei
- Department of Medical Oncology, National Cancer Center, National Clinical Research Center for Cancer, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Chaoyang District, Pan jia yuan nan Road 17, Beijing 100021, China
| | - Fei Ma
- Department of Medical Oncology, National Cancer Center, National Clinical Research Center for Cancer, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Chaoyang District, Pan jia yuan nan Road 17, Beijing 100021, China.
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2
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Han D, Wang L, Long L, Su P, Luo D, Zhang H, Li Z, Chen B, Zhao W, Zhang N, Wang X, Liang Y, Li Y, Hu G, Yang Q. The E3 Ligase TRIM4 Facilitates SET Ubiquitin-Mediated Degradation to Enhance ER-α Action in Breast Cancer. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2201701. [PMID: 35843886 PMCID: PMC9443474 DOI: 10.1002/advs.202201701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 06/10/2022] [Indexed: 06/15/2023]
Abstract
Estrogen receptor alpha (ER-α) action is critical for hormone-dependent breast cancer, and ER-α dysregulation can lead to the emergence of resistance to endocrine therapy. Here, it is found that TRIM4 is downregulated in tamoxifen (TAM)-resistant breast cancer cells, while the loss of TRIM4 is associated with an unfavorable prognosis. In vitro and in vivo experiments confirm that TRIM4 increased ER-α expression and the sensitivity of breast cancer cells to TAM. Mechanistically, TRIM4 is found to target SET, and TRIM4-SET interactions are mediated by the RING and B-box domains of TRIM4 and the carboxyl terminus of SET. Moreover, it is determined that TRIM4 catalyzed the K48-linked polyubiquitination of SET (K150 and K172), promoting its proteasomal degradation and disassociation from p53 and PP2A. Once released, p53 and PP2A are able to further promote ESR1 gene transcription and enhance mRNA stability. Moreover, univariate and multivariate Cox proportional hazards regression analyses confirm that TRIM4 expression is an independent predictor of overall survival and recurrence-free survival outcomes in patients with ER-α positive breast cancer. Taken together, the data highlights a previously undiscovered mechanism and suggest that TRIM4 is a valuable biomarker that can be analyzed to predict response to endocrine therapy in breast cancer patients.
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Affiliation(s)
- Dianwen Han
- Department of Breast Surgery, General SurgeryQilu Hospital of Shandong UniversityJinanShandong250012China
| | - Lijuan Wang
- Pathology Tissue BankQilu Hospital of Shandong UniversityJinanShandong250012China
| | - Li Long
- Department of Breast Surgery, General SurgeryQilu Hospital of Shandong UniversityJinanShandong250012China
- Mianyang Central HospitalSchool of MedicineUniversity of Electronic Science and Technology of ChinaMianyangSichuan621000China
| | - Peng Su
- Department of PathologyQilu Hospital of Shandong UniversityJinanShandong250012China
| | - Dan Luo
- Department of Breast Surgery, General SurgeryQilu Hospital of Shandong UniversityJinanShandong250012China
| | - Hanwen Zhang
- Department of Breast Surgery, General SurgeryQilu Hospital of Shandong UniversityJinanShandong250012China
| | - Zheng Li
- Department of Breast Surgery, General SurgeryQilu Hospital of Shandong UniversityJinanShandong250012China
| | - Bing Chen
- Pathology Tissue BankQilu Hospital of Shandong UniversityJinanShandong250012China
| | - Wenjing Zhao
- Pathology Tissue BankQilu Hospital of Shandong UniversityJinanShandong250012China
| | - Ning Zhang
- Department of Breast Surgery, General SurgeryQilu Hospital of Shandong UniversityJinanShandong250012China
| | - Xiaolong Wang
- Department of Breast Surgery, General SurgeryQilu Hospital of Shandong UniversityJinanShandong250012China
| | - Yiran Liang
- Department of Breast Surgery, General SurgeryQilu Hospital of Shandong UniversityJinanShandong250012China
| | - Yaming Li
- Department of Breast Surgery, General SurgeryQilu Hospital of Shandong UniversityJinanShandong250012China
| | - Guohong Hu
- The Key Laboratory of Stem Cell BiologyInstitute of Health SciencesShanghai Institutes for Biological SciencesChinese Academy of Sciences & Shanghai Jiao Tong University School of MedicineUniversity of Chinese Academy of SciencesShanghai200233China
| | - Qifeng Yang
- Department of Breast Surgery, General SurgeryQilu Hospital of Shandong UniversityJinanShandong250012China
- Pathology Tissue BankQilu Hospital of Shandong UniversityJinanShandong250012China
- Research Institute of Breast CancerShandong UniversityJinanShandong250012China
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3
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Abdelhameed RFA, Eltamany EE, Hal DM, Ibrahim AK, AboulMagd AM, Al-Warhi T, Youssif KA, Abd El-Kader AM, Hassanean HA, Fayez S, Bringmann G, Ahmed SA, Abdelmohsen UR. New Cytotoxic Cerebrosides from the Red Sea Cucumber Holothuria spinifera Supported by In-Silico Studies. Mar Drugs 2020; 18:E405. [PMID: 32752177 PMCID: PMC7460232 DOI: 10.3390/md18080405] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/17/2020] [Accepted: 07/23/2020] [Indexed: 12/18/2022] Open
Abstract
Bioactivity-guided fractionation of a methanolic extract of the Red Sea cucumber Holothuria spinifera and LC-HRESIMS-assisted dereplication resulted in the isolation of four compounds, three new cerebrosides, spiniferosides A (1), B (2), and C (3), and cholesterol sulfate (4). The chemical structures of the isolated compounds were established on the basis of their 1D NMR and HRMS spectral data. Metabolic profiling of the H. spinifera extract indicated the presence of diverse secondary metabolites, mostly hydroxy fatty acids, diterpenes, triterpenes, and cerebrosides. The isolated compounds were tested for their in vitro cytotoxicities against the breast adenocarcinoma MCF-7 cell line. Compounds 1, 2, 3, and 4 displayed promising cytotoxic activities against MCF-7 cells, with IC50 values of 13.83, 8.13, 8.27, and 35.56 µM, respectively, compared to that of the standard drug doxorubicin (IC50 8.64 µM). Additionally, docking studies were performed for compounds 1, 2, 3, and 4 to elucidate their binding interactions with the active site of the SET protein, an inhibitor of protein phosphatase 2A (PP2A), which could explain their cytotoxic activity. This study highlights the important role of these metabolites in the defense mechanism of the sea cucumber against fouling organisms and the potential uses of these active molecules in the design of new anticancer agents.
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Affiliation(s)
- Reda F A Abdelhameed
- Department of Pharmacognosy, Faculty of Pharmacy, Suez Canal University, Ismailia 41522, Egypt
| | - Enas E Eltamany
- Department of Pharmacognosy, Faculty of Pharmacy, Suez Canal University, Ismailia 41522, Egypt
| | - Dina M Hal
- Department of Pharmacognosy, Faculty of Pharmacy, Suez Canal University, Ismailia 41522, Egypt
| | - Amany K Ibrahim
- Department of Pharmacognosy, Faculty of Pharmacy, Suez Canal University, Ismailia 41522, Egypt
| | - Asmaa M AboulMagd
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Nahda University, Beni Suef 62513, Egypt
| | - Tarfah Al-Warhi
- Department of Chemistry, College of Science, Princess Nourah bint Abdulrahman University, Riyadh 13414, Saudi Arabia
| | - Khayrya A Youssif
- Department of Pharmacognosy, Faculty of Pharmacy, Modern University for Technology and Information, Cairo 11566, Egypt
| | - Adel M Abd El-Kader
- Department of Pharmacognosy, Faculty of Pharmacy, Deraya University, New Minia 61111, Egypt
- Department of Pharmacognosy, Faculty of Pharmacy, Al-Azhar University, Assiut 71524, Egypt
| | - Hashim A Hassanean
- Department of Pharmacognosy, Faculty of Pharmacy, Suez Canal University, Ismailia 41522, Egypt
| | - Shaimaa Fayez
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
- Department of Pharmacognosy, Faculty of Pharmacy, Ain-Shams University, Cairo 11566, Egypt
| | - Gerhard Bringmann
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Safwat A Ahmed
- Department of Pharmacognosy, Faculty of Pharmacy, Suez Canal University, Ismailia 41522, Egypt
| | - Usama Ramadan Abdelmohsen
- Department of Pharmacognosy, Faculty of Pharmacy, Deraya University, New Minia 61111, Egypt
- Department of Pharmacognosy, Faculty of Pharmacy, Minia University, Minia 61519, Egypt
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Inflammatory macrophage derived TNFα downregulates estrogen receptor α via FOXO3a inactivation in human breast cancer cells. Exp Cell Res 2020; 390:111932. [PMID: 32145253 DOI: 10.1016/j.yexcr.2020.111932] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 02/24/2020] [Accepted: 02/27/2020] [Indexed: 02/06/2023]
Abstract
Patients with estrogen receptor α positive (ERα+) breast cancer can respond to endocrine therapy, but treatment resistance is common and associated with downregulation of ERα expression in the dormant residual cells. Here we show, using long-term NSG xenograft models of human breast cancer and primary human monocytes, in vitro primary cell cultures and tumors from breast cancer patients, that macrophage derived tumor necrosis factor alpha (TNFα) downregulates ERα in breast cancer cells via inactivation of the transcription factor Forkhead box O transcription factor 3a (FOXO3a). Moreover, presence of tumor associated macrophages in the primary tumor of breast cancer patients, was associated with ERα negativity, and with worse prognosis in patients with ERα+ tumors. We propose that pro-inflammatory macrophages, despite being tumoricidal, may have direct effects on tumor progression and endocrine resistance in breast cancer patients. Our findings suggest that TNFα antagonists should be evaluated for treatment of ERα+ breast cancer.
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Zhao H, Li D, Zhang B, Qi Y, Diao Y, Zhen Y, Shu X. PP2A as the Main Node of Therapeutic Strategies and Resistance Reversal in Triple-Negative Breast Cancer. Molecules 2017; 22:molecules22122277. [PMID: 29261144 PMCID: PMC6149800 DOI: 10.3390/molecules22122277] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 12/07/2017] [Accepted: 12/19/2017] [Indexed: 12/31/2022] Open
Abstract
Triple negative breast cancer (TNBC), is defined as a type of tumor lacking the expression of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2). The ER, PR and HER2 are usually the molecular therapeutic targets for breast cancers, but they are ineffective for TNBC because of their negative expressions, so chemotherapy is currently the main treatment strategy in TNBC. However, drug resistance remains a major impediment to TNBC chemotherapeutic treatment. Recently, the protein phosphatase 2A (PP2A) has been found to regulate the phosphorylation of some substrates involved in the relevant target of TNBC, such as cell cycle control, DNA damage responses, epidermal growth factor receptor, immune modulation and cell death resistance, which may be the effective therapeutic strategies or influence drug sensitivity to TNBCs. Furthermore, PP2A has also been found that could induce ER re-expression in ER-negative breast cancer cells, and which suggests PP2A could promote the sensitivity of tamoxifen to TNBCs as a resistance reversal agent. In this review, we will summarize the potential therapeutic value of PP2A as the main node in developing targeting agents, disrupting resistance or restoring drug sensitivity in TNBC.
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Affiliation(s)
- Henan Zhao
- Department of Pathophysiology, Dalian Medical University, Dalian 116044, China.
| | - Duojiao Li
- Kamp Pharmaceutical Co. Ltd., Changsha 410008, China.
| | - Baojing Zhang
- College of Pharmacy, Dalian Medical University, Dalian 116044, China.
| | - Yan Qi
- College of Pharmacy, Dalian Medical University, Dalian 116044, China.
| | - Yunpeng Diao
- College of Pharmacy, Dalian Medical University, Dalian 116044, China.
| | - Yuhong Zhen
- College of Pharmacy, Dalian Medical University, Dalian 116044, China.
| | - Xiaohong Shu
- College of Pharmacy, Dalian Medical University, Dalian 116044, China.
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Cristóbal I, Torrejón B, Martínez-Useros J, Madoz-Gurpide J, Rojo F, García-Foncillas J. PP2A regulates signaling through hormonal receptors in breast cancer with important therapeutic implications. Biochim Biophys Acta Rev Cancer 2017; 1868:435-438. [PMID: 28916342 DOI: 10.1016/j.bbcan.2017.08.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 08/10/2017] [Accepted: 08/31/2017] [Indexed: 11/27/2022]
Abstract
The functional inhibition of protein phosphatase 2A (PP2A) has emerged in the last years as a common alteration in breast cancer that determines poor outcome and contributes to disease progression and aggressiveness. Furthermore, expression of estrogen receptor (ER) is a high relevant molecular event with key therapeutic implications in breast cancer, and androgen receptor (AR) signaling is involved in the pathogenesis of breast cancer and represents a novel target with crescent importance in this disease. In this review, we summarize the role of the tumor suppressor PP2A in modulating ER and AR signaling in breast cancer, the molecular mechanisms involved, and its biological and therapeutic impact.
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Affiliation(s)
- Ion Cristóbal
- Translational Oncology Division, Oncohealth Institute, IIS-Fundacion Jimenez Diaz, UAM, University Hospital "Fundacion Jimenez Diaz", Madrid, Spain.
| | - Blanca Torrejón
- Translational Oncology Division, Oncohealth Institute, IIS-Fundacion Jimenez Diaz, UAM, University Hospital "Fundacion Jimenez Diaz", Madrid, Spain
| | - Javier Martínez-Useros
- Translational Oncology Division, Oncohealth Institute, IIS-Fundacion Jimenez Diaz, UAM, University Hospital "Fundacion Jimenez Diaz", Madrid, Spain
| | | | - Federico Rojo
- Pathology Department, IIS "Fundación Jiménez Diaz", Madrid, Spain.
| | - Jesús García-Foncillas
- Translational Oncology Division, Oncohealth Institute, IIS-Fundacion Jimenez Diaz, UAM, University Hospital "Fundacion Jimenez Diaz", Madrid, Spain.
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7
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Fukagawa S, Miyata K, Yotsumoto F, Kiyoshima C, Nam SO, Anan H, Katsuda T, Miyahara D, Murata M, Yagi H, Shirota K, Yasunaga S, Kato K, Miyamoto S. MicroRNA-135a-3p as a promising biomarker and nucleic acid therapeutic agent for ovarian cancer. Cancer Sci 2017; 108:886-896. [PMID: 28231414 PMCID: PMC5448652 DOI: 10.1111/cas.13210] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Revised: 02/11/2017] [Accepted: 02/15/2017] [Indexed: 12/12/2022] Open
Abstract
Ovarian cancer is the most lethal gynecologic malignancy. Recently, several molecularly targeted anticancer agents have been developed for ovarian cancer; however, its prognosis remains extremely poor. The development of molecularly targeted therapy, as well as companion diagnostics, is required to improve outcomes for patients with ovarian cancer. In this study, to identify microRNAs (miRNAs) involved in the progression of ovarian cancer we analyzed serum miRNAs in patients with ovarian cancer using miRNA array and quantitative RT-PCR and examined the anticancer properties of miRNA expression in ovarian cancer cells. In patients with ovarian cancer, high amount of miR-135a-3p in serum samples was significantly associated with favorable clinical prognosis. The amount of miR-135a-3p was significantly decreased in patients with ovarian cancer compared with patients with ovarian cysts or normal ovaries. In SKOV-3 and ES-2 human ovarian cancer cells, enhanced expression of miR-135a-3p induced drug sensitivity to cisplatin and paclitaxel and suppressed cell proliferation and xenograft tumor growth. These findings suggest that miR-135a-3p may be considered as a biomarker and a therapeutic agent in ovarian cancer.
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Affiliation(s)
- Satoshi Fukagawa
- Department of Obstetrics and GynecologyFukuoka UniversityFukuokaJapan
- Central Research Institute for Advanced Molecular MedicineFukuoka UniversityFukuokaJapan
| | - Kohei Miyata
- Department of Obstetrics and GynecologyFukuoka UniversityFukuokaJapan
- Central Research Institute for Advanced Molecular MedicineFukuoka UniversityFukuokaJapan
| | | | - Chihiro Kiyoshima
- Department of Obstetrics and GynecologyFukuoka UniversityFukuokaJapan
- Central Research Institute for Advanced Molecular MedicineFukuoka UniversityFukuokaJapan
| | - Sung Ouk Nam
- Department of Obstetrics and GynecologyFukuoka UniversityFukuokaJapan
| | - Haruchika Anan
- Department of Obstetrics and GynecologyFukuoka UniversityFukuokaJapan
| | - Takahiro Katsuda
- Department of Obstetrics and GynecologyFukuoka UniversityFukuokaJapan
| | - Daisuke Miyahara
- Department of Obstetrics and GynecologyFukuoka UniversityFukuokaJapan
| | - Masaharu Murata
- Department of Obstetrics and GynecologyFukuoka UniversityFukuokaJapan
| | - Hiroshi Yagi
- Department of Obstetrics and GynecologyFaculty of MedicineKyushu UniversityFukuokaJapan
| | - Kyoko Shirota
- Department of Obstetrics and GynecologyFukuoka UniversityFukuokaJapan
| | - Shin'ichiro Yasunaga
- Central Research Institute for Advanced Molecular MedicineFukuoka UniversityFukuokaJapan
- Department of BiochemistryFaculty of MedicineFukuoka UniversityFukuokaJapan
| | - Kiyoko Kato
- Department of Obstetrics and GynecologyFaculty of MedicineKyushu UniversityFukuokaJapan
| | - Shingo Miyamoto
- Department of Obstetrics and GynecologyFukuoka UniversityFukuokaJapan
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Abstract
Protein phosphatase 2A (PP2A) plays a critical multi-faceted role in the regulation of the cell cycle. It is known to dephosphorylate over 300 substrates involved in the cell cycle, regulating almost all major pathways and cell cycle checkpoints. PP2A is involved in such diverse processes by the formation of structurally distinct families of holoenzymes, which are regulated spatially and temporally by specific regulators. Here, we review the involvement of PP2A in the regulation of three cell signaling pathways: wnt, mTOR and MAP kinase, as well as the G1→S transition, DNA synthesis and mitotic initiation. These processes are all crucial for proper cell survival and proliferation and are often deregulated in cancer and other diseases.
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Affiliation(s)
- Nathan Wlodarchak
- a McArdle Laboratory for Cancer Research, University of Wisconsin-Madison , Madison , WI , USA
| | - Yongna Xing
- a McArdle Laboratory for Cancer Research, University of Wisconsin-Madison , Madison , WI , USA
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9
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Quantitative proteomic analyses of mammary organoids reveals distinct signatures after exposure to environmental chemicals. Proc Natl Acad Sci U S A 2016; 113:E1343-51. [PMID: 26903627 DOI: 10.1073/pnas.1600645113] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Common environmental contaminants such as bisphenols and phthalates and persistent contaminants such as polychlorinated biphenyls are thought to influence tissue homeostasis and carcinogenesis by acting as disrupters of endocrine function. In this study we investigated the direct effects of exposure to bisphenol A (BPA), mono-n-butyl phthalate (Pht), and polychlorinated biphenyl 153 (PCB153) on the proteome of primary organotypic cultures of the mouse mammary gland. At low-nanomolar doses each of these agents induced distinct effects on the proteomes of these cultures. Although BPA treatment produced effects that were similar to those induced by estradiol, there were some notable differences, including a reduction in the abundance of retinoblastoma-associated protein and increases in the Rho GTPases Ras-related C3 botulinum toxin substrate 1 (Rac1) and cell division cycle protein CDC42. Both Pht and PCB153 induced changes that were distinct from those induced by estrogen, including decreased levels of the transcriptional corepressor C-terminal binding protein 1. Interestingly, the three chemicals appeared to alter the abundance of distinct splice forms of many proteins as well as the abundance of several proteins that regulate RNA splicing. Our combined results indicate that the three classes of chemical have distinct effects on the proteome of normal mouse mammary cultures, some estrogen-like but most estrogen independent, that influence diverse biological processes including apoptosis, cell adhesion, and proliferation.
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Rincón R, Cristóbal I, Zazo S, Arpí O, Menéndez S, Manso R, Lluch A, Eroles P, Rovira A, Albanell J, García-Foncillas J, Madoz-Gúrpide J, Rojo F. PP2A inhibition determines poor outcome and doxorubicin resistance in early breast cancer and its activation shows promising therapeutic effects. Oncotarget 2015; 6:4299-314. [PMID: 25726524 PMCID: PMC4414191 DOI: 10.18632/oncotarget.3012] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 12/31/2014] [Indexed: 11/26/2022] Open
Abstract
The protein phosphatase 2A (PP2A) is a key tumor suppressor which has emerged as a novel molecular target in some human cancers. Here, we show that PP2A inhibition is a common event in breast cancer and identified PP2A phosphorylation and deregulation SET and CIP2A as molecular contributing mechanisms to inactivate PP2A. Interestingly, restoration of PP2A activity after FTY720 treatment reduced cell growth, induced apoptosis and decreased AKT and ERK activation. Moreover, FTY720 led to PP2A activation then enhancing doxorubicin-induced antitumor effects both in vitro and in vivo. PP2A inhibition (CPscore: PP2A phosphorylation and/or CIP2A overexpression) was detected in 27% of cases (62/230), and associated with grade (p = 0.017), relapse (p < 0.001), negative estrogen (p < 0.001) and progesterone receptor expression (p < 0.001), HER2-positive tumors (p = 0.049), Ki-67 expression (p < 0.001), and higher AKT (p < 0.001) and ERK (p < 0.001) phosphorylation. Moreover, PP2A inhibition determined shorter overall (p = 0.006) and event-free survival (p = 0.003), and multivariate analysis confirmed its independent prognostic impact. Altogether, our results indicate that PP2A is frequently inactivated in breast cancer and determines worse outcome, and its restoration using PP2A activators represents an alternative therapeutic strategy in this disease.
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Affiliation(s)
- Raúl Rincón
- Translational Oncology Division, Oncohealth Institute, Health Research Institute FJD-UAM, University Hospital "Fundación Jiménez Diaz", Madrid, Spain
| | - Ion Cristóbal
- Translational Oncology Division, Oncohealth Institute, Health Research Institute FJD-UAM, University Hospital "Fundación Jiménez Diaz", Madrid, Spain
| | - Sandra Zazo
- Pathology Department, IIS "Fundación Jiménez Diaz", Madrid, Spain
| | - Oriol Arpí
- Medical Oncology Department, Hospital del Mar, Barcelona, Spain
| | - Silvia Menéndez
- Medical Oncology Department, Hospital del Mar, Barcelona, Spain
| | - Rebeca Manso
- Pathology Department, IIS "Fundación Jiménez Diaz", Madrid, Spain
| | - Ana Lluch
- Institute of Health Research INCLIVA, Valencia, Spain
| | - Pilar Eroles
- Institute of Health Research INCLIVA, Valencia, Spain
| | - Ana Rovira
- Medical Oncology Department, Hospital del Mar, Barcelona, Spain
| | - Joan Albanell
- Medical Oncology Department, Hospital del Mar, Barcelona, Spain
| | - Jesús García-Foncillas
- Translational Oncology Division, Oncohealth Institute, Health Research Institute FJD-UAM, University Hospital "Fundación Jiménez Diaz", Madrid, Spain
| | | | - Federico Rojo
- Pathology Department, IIS "Fundación Jiménez Diaz", Madrid, Spain.,Medical Oncology Department, Hospital del Mar, Barcelona, Spain
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11
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Li Y, Wang X, Vural S, Mishra NK, Cowan KH, Guda C. Exome analysis reveals differentially mutated gene signatures of stage, grade and subtype in breast cancers. PLoS One 2015; 10:e0119383. [PMID: 25803781 PMCID: PMC4372331 DOI: 10.1371/journal.pone.0119383] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 01/30/2015] [Indexed: 12/17/2022] Open
Abstract
Breast cancers exhibit highly heterogeneous molecular profiles. Although gene expression profiles have been used to predict the risks and prognostic outcomes of breast cancers, the high variability of gene expression limits its clinical application. In contrast, genetic mutation profiles would be more advantageous than gene expression profiles because genetic mutations can be stably detected and the mutational heterogeneity widely exists in breast cancer genomes. We analyzed 98 breast cancer whole exome samples that were sorted into three subtypes, two grades and two stages. The sum deleterious effect of all mutations in each gene was scored to identify differentially mutated genes (DMGs) for this case-control study. DMGs were corroborated using extensive published knowledge. Functional consequences of deleterious SNVs on protein structure and function were also investigated. Genes such as ERBB2, ESP8, PPP2R4, KIAA0922, SP4, CENPJ, PRCP and SELP that have been experimentally or clinically verified to be tightly associated with breast cancer prognosis are among the DMGs identified in this study. We also identified some genes such as ARL6IP5, RAET1E, and ANO7 that could be crucial for breast cancer development and prognosis. Further, SNVs such as rs1058808, rs2480452, rs61751507, rs79167802, rs11540666, and rs2229437 that potentially influence protein functions are observed at significantly different frequencies in different comparison groups. Protein structure modeling revealed that many non-synonymous SNVs have a deleterious effect on protein stability, structure and function. Mutational profiling at gene- and SNV-level revealed differential patterns within each breast cancer comparison group, and the gene signatures correlate with expected prognostic characteristics of breast cancer classes. Some of the genes and SNVs identified in this study show high promise and are worthy of further investigation by experimental studies.
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Affiliation(s)
- You Li
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Xiaosheng Wang
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Suleyman Vural
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Nitish K. Mishra
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Kenneth H. Cowan
- Fred and Pamela Buffett Cancer Center, Nebraska Medical Center, Omaha, Nebraska, United States of America
- Eppley Institute for Cancer Research, Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Chittibabu Guda
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
- Fred and Pamela Buffett Cancer Center, Nebraska Medical Center, Omaha, Nebraska, United States of America
- Eppley Institute for Cancer Research, Nebraska Medical Center, Omaha, Nebraska, United States of America
- Bioinformatics and Systems Biology Core, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
- * E-mail:
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Simões J, Amado FM, Vitorino R, Helguero LA. A meta-analysis to evaluate the cellular processes regulated by the interactome of endogenous and over-expressed estrogen receptor alpha. Oncoscience 2015; 2:487-496. [PMID: 26097882 PMCID: PMC4468335 DOI: 10.18632/oncoscience.138] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Accepted: 03/04/2015] [Indexed: 01/08/2023] Open
Abstract
The nature of the proteins complexes that regulate ERα subcellular localization and activity is still an open question in breast cancer biology. Identification of such complexes will help understand development of endocrine resistance in ER+ breast cancer. Mass spectrometry (MS) has allowed comprehensive analysis of the ERα interactome. We have compared six published works analyzing the ERα interactome of MCF-7 and HeLa cells in order to identify a shared or different pathway-related fingerprint. Overall, 806 ERα interacting proteins were identified. The cellular processes were differentially represented according to the ERα purification methodology, indicating that the methodologies used are complementary. While in MCF-7 cells, the interactome of endogenous and over-expressed ERα essentially represents the same biological processes and cellular components, the proteins identified were not over-lapping; thus, suggesting that the biological response may differ as the regulatory/participating proteins in these complexes are different. Interestingly, biological processes uniquely associated to ERα over-expressed in HeLa cell line included L-serine biosynthetic process, cellular amino acid biosynthetic process and cell redox homeostasis. In summary, all the approaches analyzed in this meta-analysis are valid and complementary; in particular, for those cases where the processes occur at low frequency with normal ERα levels, and can be identified when the receptor is over-expressed. However special effort should be put into validating these findings in cells expressing physiological ERα levels.
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Affiliation(s)
- Joana Simões
- Mass Spectrometry Centre, QOPNA Research Unit, Department of Chemistry, Universidade de Aveiro, Campus Universitário de Santiago, Aveiro, Portugal
| | - Francisco M Amado
- Mass Spectrometry Centre, QOPNA Research Unit, Department of Chemistry, Universidade de Aveiro, Campus Universitário de Santiago, Aveiro, Portugal.,School of Healh Sciences, Universidade de Aveiro, Portugal
| | - Rui Vitorino
- Mass Spectrometry Centre, QOPNA Research Unit, Department of Chemistry, Universidade de Aveiro, Campus Universitário de Santiago, Aveiro, Portugal.,Institute for Research in Biomedicine - iBiMED, Health Sciences Program, Universidade de Aveiro, Portugal
| | - Luisa A Helguero
- Mass Spectrometry Centre, QOPNA Research Unit, Department of Chemistry, Universidade de Aveiro, Campus Universitário de Santiago, Aveiro, Portugal.,Institute for Research in Biomedicine - iBiMED, Health Sciences Program, Universidade de Aveiro, Portugal
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13
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Zhang H, Liu J, Zhao X, Liang B, Wen Z, Li M. Loss of PP2A and PTEN immunoexpression coexists with survivin overexpression in adenomyosis. Reprod Biol 2014; 14:200-5. [DOI: 10.1016/j.repbio.2014.04.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 04/22/2014] [Accepted: 04/24/2014] [Indexed: 10/25/2022]
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Baldacchino S, Saliba C, Petroni V, Fenech AG, Borg N, Grech G. Deregulation of the phosphatase, PP2A is a common event in breast cancer, predicting sensitivity to FTY720. EPMA J 2014; 5:3. [PMID: 24460909 PMCID: PMC3913630 DOI: 10.1186/1878-5085-5-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 01/09/2014] [Indexed: 01/01/2023]
Abstract
Background The most commonly used biomarkers to predict the response of breast cancer patients to therapy are the oestrogen receptor (ER), progesterone receptor (PgR), and human epidermal growth factor receptor 2 (HER2). Patients positive for these biomarkers are eligible for specific therapies such as endocrine treatment in the event of ER and PgR positivity, and the monoclonal antibody, trastuzumab, in the case of HER2-positive patients. Patients who are negative for these three biomarkers, the so-called triple negatives, however, derive little benefit from such therapies and are associated with a worse prognosis. Deregulation of the protein serine/threonine phosphatase type 2A (PP2A) and its regulatory subunits is a common event in breast cancer, providing a possible target for therapy. Methods The data portal, cBioPortal for Cancer Genomics was used to investigate the incidence of conditions that are associated with low phosphatase activity. Four (4) adherent human breast cancer cell lines, MDA-MB-468, MDA-MB-436, Hs578T and BT-20 were cultured to assess their viability when exposed to various dosages of rapamycin or FTY720. In addition, RNA was extracted and cDNA was synthesised to amplify the coding sequence of PPP2CA. Amplification was followed by high-resolution melting to identify variations. Results and conclusion The sequence of PPP2CA was found to be conserved across a diverse panel of solid tumour and haematological cell lines, suggesting that low expression of PPP2CA and differential binding of inhibitory PPP2CA regulators are the main mechanisms of PP2A deregulation. Interestingly, the cBioPortal for Cancer Genomics shows that PP2A is deregulated in 59.6% of basal breast tumours. Viability assays performed to determine the sensitivity of a panel of breast cancer cell lines to FTY720, a PP2A activator, indicated that cell lines associated with ER loss are sensitive to lower doses of FTY720. The subset of patients with suppressed PP2A activity is potentially eligible for treatment using therapies which target the PI3K/AKT/mTOR pathway, such as phosphatase activators.
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Affiliation(s)
- Shawn Baldacchino
- Department of Pathology, Medical School, University of Malta, Msida MSD2090, Malta
| | - Christian Saliba
- Department of Pathology, Medical School, University of Malta, Msida MSD2090, Malta
| | - Vanessa Petroni
- Department of Clinical Pharmacology and Therapeutics, University of Malta, Msida MSD2090, Malta
| | - Anthony G Fenech
- Department of Clinical Pharmacology and Therapeutics, University of Malta, Msida MSD2090, Malta
| | - Nigel Borg
- Department of Pathology, Medical School, University of Malta, Msida MSD2090, Malta
| | - Godfrey Grech
- Department of Pathology, Medical School, University of Malta, Msida MSD2090, Malta
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Ahn J, Yoon Y, Yeu Y, Lee H, Park S. Impact of TGF-b on breast cancer from a quantitative proteomic analysis. Comput Biol Med 2013; 43:2096-102. [DOI: 10.1016/j.compbiomed.2013.09.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 09/22/2013] [Accepted: 09/25/2013] [Indexed: 02/04/2023]
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Suresh PS, Ma S, Migliaccio A, Chen G. Protein-Tyrosine Phosphatase H1 Increases Breast Cancer Sensitivity to Antiestrogens by Dephosphorylating Estrogen Receptor at Tyr537. Mol Cancer Ther 2013; 13:230-8. [DOI: 10.1158/1535-7163.mct-13-0610] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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17
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Arrouss I, Nemati F, Roncal F, Wislez M, Dorgham K, Vallerand D, Rabbe N, Karboul N, Carlotti F, Bravo J, Mazier D, Decaudin D, Rebollo A. Specific targeting of caspase-9/PP2A interaction as potential new anti-cancer therapy. PLoS One 2013; 8:e60816. [PMID: 23637769 PMCID: PMC3634037 DOI: 10.1371/journal.pone.0060816] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 03/03/2013] [Indexed: 01/02/2023] Open
Abstract
PURPOSE PP2A is a serine/threonine phosphatase critical to physiological processes, including apoptosis. Cell penetrating peptides are molecules that can translocate into cells without causing membrane damage. Our goal was to develop cell-penetrating fusion peptides specifically designed to disrupt the caspase-9/PP2A interaction and evaluate their therapeutic potential in vitro and in vivo. EXPERIMENTAL DESIGN We generated a peptide containing a penetrating sequence associated to the interaction motif between human caspase-9 and PP2A (DPT-C9h), in order to target their association. Using tumour cell lines, primary human cells and primary human breast cancer (BC) xenografts, we investigated the capacity of DPT-C9h to provoke apoptosis in vitro and inhibition of tumour growth (TGI) in vivo. DPT-C9h was intraperitoneally administered at doses from 1 to 25 mg/kg/day for 5 weeks. Relative Tumour Volume (RTV) was calculated. RESULTS We demonstrated that DPT-C9h specifically target caspase-9/PP2A interaction in vitro and in vivo and induced caspase-9-dependent apoptosis in cancer cell lines. DPT-C9h also induced significant TGI in BC xenografts models. The mouse-specific peptide DPT-C9 also induced TGI in lung (K-Ras model) and breast cancer (PyMT) models. DPT-C9h has a specific effect on transformed B cells isolated from chronic lymphocytic leukemia patients without any effect on primary healthy cells. Finally, neither toxicity nor immunogenic responses were observed. CONCLUSION Using the cell-penetrating peptides blocking caspase-9/PP2A interactions, we have demonstrated that DPT-C9h had a strong therapeutic effect in vitro and in vivo in mouse models of tumour progression.
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Affiliation(s)
- Issam Arrouss
- Inserm UMRS 945, Hôpital Pitié Salpêtrière, Université Pierre et Marie Curie, Paris, France
| | - Fariba Nemati
- Laboratory of Preclinical Investigation, Translational Research Department, Institut Curie, Paris, France
| | - Fernando Roncal
- Centro Nacional de Biotecnologia, Campus de Cantoblanco, Universidad Autónoma de Madrid, Madrid, Spain
| | - Marie Wislez
- URF Pierre et Marie Curie, Hôpital Tenon, Paris, France
| | - Karim Dorgham
- Inserm UMRS 945, Hôpital Pitié Salpêtrière, Université Pierre et Marie Curie, Paris, France
| | - David Vallerand
- Laboratory of Preclinical Investigation, Translational Research Department, Institut Curie, Paris, France
| | | | - Narjesse Karboul
- Laboratory of Preclinical Investigation, Translational Research Department, Institut Curie, Paris, France
| | - Françoise Carlotti
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Jeronimo Bravo
- Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Cientificas, Valencia, Spain
| | - Dominique Mazier
- Inserm UMRS 945, Hôpital Pitié Salpêtrière, Université Pierre et Marie Curie, Paris, France
| | - Didier Decaudin
- Laboratory of Preclinical Investigation, Translational Research Department, Institut Curie, Paris, France
- Department of Medical Oncology, Institut Curie, Paris, France
| | - Angelita Rebollo
- Inserm UMRS 945, Hôpital Pitié Salpêtrière, Université Pierre et Marie Curie, Paris, France
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Chen HF, Mai JR, Wan JX, Gao YF, Lin LN, Wang SZ, Chen YX, Zhang CZ, Zhang YJ, Xia B, Liao K, Lin YC, Lin ZN. Role of a novel functional variant in the PPP2R1A promoter on the regulation of PP2A-Aalpha and the risk of hepatocellular carcinoma. PLoS One 2013; 8:e59574. [PMID: 23555712 PMCID: PMC3612049 DOI: 10.1371/journal.pone.0059574] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 02/15/2013] [Indexed: 02/06/2023] Open
Abstract
Previously, we identified the genetic variant −241 (−/G) (rs11453459) in the PP2A-Aα gene (PPP2R1A) promoter and demonstrated that this variant influences the DNA-binding affinity of nuclear factor-kappa B (NF-κB). In this study, we further confirmed that the transcriptional activity of PPP2R1A may be regulated by NF-κB through the functional genetic variant −241 (−/G). Moreover, we also demonstrated that the methylation status of CpG islands in the promoter of PPP2R1A influences the activity of this gene promoter. Few studies have examined the role of this −241 (−/G) variant in genetic or epigenetic regulation in hepatocellular carcinoma (HCC). To investigate whether this functional variant in the PPP2R1A promoter is associated with the risk of HCC and confirm the function of the −241 (−/G) variant in the HCC population, we conducted a case-control study involving 251 HCC cases and 252 cancer-free controls from a Han population in southern China. Compared with the −241 (−−) homozygote, the heterozygous −241 (−G) genotype (adjusted OR = 0.32, 95% confidence interval (CI) = 0.17–0.58, P<0.001) and the −241 (−G)/(GG) genotypes (adjusted OR = 0.38, 95% CI = 0.22–0.67, P = 0.001) were both significantly associated with a reduced risk of HCC. Stratification analysis indicated that the protective role of −241 (−G) was more pronounced in individuals who were ≤ 40 years of age, female and HBV-negative. Our data suggest that the transcriptional activity of PPP2R1A is regulated by NF-κB through the −241 (−/G) variant and by the methylation of the promoter region. Moreover, the functional −241 (−/G) variant in the PPP2R1A promoter contributes to the decreased risk of HCC. These findings contribute novel information regarding the gene transcription of PPP2R1A regulated by the polymorphism and methylation in the promoter region through genetic and epigenetic mechanisms in hepatocarcinogenesis.
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Affiliation(s)
- Hui-Feng Chen
- Guangdong Provincial Key Laboratory of Food, Nutrition and Health, School of Public Health, Sun Yat-sen University, Guangzhou, PR China
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Vazquez A, Kulkarni D, Grochola LF, Bond GL, Barnard N, Toppmeyer D, Levine AJ, Hirshfield KM. A genetic variant in a PP2A regulatory subunit encoded by the PPP2R2B gene associates with altered breast cancer risk and recurrence. Int J Cancer 2011; 128:2335-43. [PMID: 20669227 DOI: 10.1002/ijc.25582] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A recent candidate gene association study identified a single nucleotide polymorphism (SNP) in the PPP2R2B gene (rs319217, A/G) that manifests allelic differences in the cellular responses to treatment with chemotherapeutic agents (Vazquez et al., Nat Rev Drug Discov 2008;7:979-87). This gene encodes a regulatory subunit of protein phosphatase 2A (PP2A), one of the major Ser/Thr phosphatases implicated in the negative control of cell growth and division. Given the tumor suppressor activities of PP2A, here we evaluate whether this genetic variant associates with the age of diagnosis and recurrence of breast cancer in women. To investigate the linkage disequilibrium in the vicinity of this SNP, PPP2R2B haplotypes were analyzed using HapMap data for 90 Caucasians. It is found that the A variant of rs319217 tags a haplotype that appears tobe under positive selection in the Caucasian population, implying that this SNP is functional. Subsequently, associations with cellular responses were investigated using data reported by the NCI anticancer drug screen and associations with breast cancer clinical variables were analyzed in a cohort of 819 Caucasian women. The A allele associates with a better response of tumor derived cell lines, lower risk of breast cancer recurrence, later time to recurrence, and later age of diagnosis of breast cancer in Caucasian women. Taken together these results indicate that the A variant of the rs319217 SNP is a marker of better prognosis in breast cancer.
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Affiliation(s)
- Alexei Vazquez
- Department of Radiation Oncology, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick, NJ, USA.
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20
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Yao Y, Brodie AMH, Davidson NE, Kensler TW, Zhou Q. Inhibition of estrogen signaling activates the NRF2 pathway in breast cancer. Breast Cancer Res Treat 2010; 124:585-91. [PMID: 20623181 DOI: 10.1007/s10549-010-1023-8] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Accepted: 06/26/2010] [Indexed: 12/21/2022]
Abstract
Exposure to higher levels of estrogen produces genotoxic metabolites that can stimulate mammary tumorigenesis. Induction of NF-E2-related factor 2 (NRF2)-dependent detoxifying enzymes (e.g., NAD(P)H-quinone oxidoreductase 1 (NQO1)) is considered an important mechanism of protection against estrogen-associated carcinogenesis because they would facilitate removal of toxic estrogens. Here, we studied the impact of estrogen-receptor (ER) signaling on NRF2-dependent gene transcription. In luciferase assay experiments using the 5-flanking region of the human NQO1 gene promoter, we observe that ERα ligand-binding domain (LBD) is required for estrogen inhibition of NQO1 promoter activity in estrogen-dependent breast cancer cells. Chromatin immunoprecipitation (ChIP) assay shows that estrogen recruits ERα and a class III histone deacetylase SIRT1 at the NQO1 promoter, leading to inhibition of NQO1 transcription. Inhibition of ERα expression by the antiestrogen shikonin reverses the inhibitory effect of estrogen on NQO1 expression. As a consequence, a chemoprevention study was undertaken to monitor the impact of shikonin on DNA lesions and tumor growth. Treatment of MCF-7 breast cancer cells with shikonin inhibits estrogen-induced 8-hydroxy-2-deoxyguanosine (8-OHdG), a marker of DNA damage. NQO1 deficiency promotes estrogen-dependent tumor formation, and shikonin inhibits estrogen-dependent tumor growth in an NQO1-dependent manner in MCF-7 xenografts. These results suggest that estrogen-receptor signaling pathway has an inhibitory effect on NRF2-dependent enzymes. Moreover, shikonin reverses the inhibitory effects of estrogen on this pathway and may contribute to breast cancer prevention.
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Affiliation(s)
- Yuan Yao
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Transcriptional regulation by small RNAs at sequences downstream from 3' gene termini. Nat Chem Biol 2010; 6:621-9. [PMID: 20581822 DOI: 10.1038/nchembio.400] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Accepted: 05/25/2010] [Indexed: 01/06/2023]
Abstract
Transcriptome studies reveal many noncoding transcripts overlapping 3' gene termini. The function of these transcripts is unknown. Here we have characterized transcription at the progesterone receptor (PR) locus and identified noncoding transcripts that overlap the 3' end of the gene. Small RNAs complementary to sequences beyond the 3' terminus of PR mRNA modulated expression of PR, recruited argonaute 2 to a 3' noncoding transcript, altered occupancy of RNA polymerase II, induced chromatin changes at the PR promoter and affected responses to physiological stimuli. We found that the promoter and 3' terminal regions of the PR locus are in close proximity, providing a potential mechanism for RNA-mediated control of transcription over long genomic distances. These results extend the potential for small RNAs to regulate transcription to target sequences beyond the 3' termini of mRNA.
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Yao Y, Li H, Gu Y, Davidson NE, Zhou Q. Inhibition of SIRT1 deacetylase suppresses estrogen receptor signaling. Carcinogenesis 2009; 31:382-7. [PMID: 19995796 DOI: 10.1093/carcin/bgp308] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Estrogen receptor alpha (ERalpha) mediates estrogen-dependent gene transcription, which plays a critical role in mammary gland development, reproduction and homeostasis. Histone acetyltransferases and class I and class II histone deacetylases (HDACs) cause posttranscriptional modification of histone proteins that participate in ERalpha signaling. Here, we report that human SIRT1, a class III HDAC, regulates ERalpha expression. Inhibition of SIRT1 activity by sirtinol suppresses ERalpha expression through disruption of basal transcriptional complexes at the ERalpha promoter. This effect leads to inhibition of estrogen-responsive gene expression. Our in vitro observations were further extended that SIRT1 knockout reduces ERalpha protein in mouse mammary gland. Finally, ERalpha-mediated estrogen response genes are also decreased in mouse embryonic fibroblasts derived from SIRT1-knockout mice. These results suggest that inhibition of SIRT1 deacetylase activity by either pharmacological inhibitors or genetic depletion impairs ERalpha-mediated signaling pathways.
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Affiliation(s)
- Yuan Yao
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Zhou Q, Shaw PG, Davidson NE. Inhibition of histone deacetylase suppresses EGF signaling pathways by destabilizing EGFR mRNA in ER-negative human breast cancer cells. Breast Cancer Res Treat 2009; 117:443-51. [PMID: 18683042 DOI: 10.1007/s10549-008-0148-5] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2008] [Accepted: 07/22/2008] [Indexed: 10/24/2022]
Abstract
Estrogen receptor alpha (ER)-negative human breast cancer cells frequently overexpress epidermal growth factor receptor (EGFR) and respond poorly to endocrine therapies. Our previous studies demonstrate that histone deacetylation plays a key role in ER gene silencing, and ER expression can be restored with histone deacetylase (HDAC) inhibitors in ER-negative human breast cancer cells. Whether inhibition of HDAC also alters epidermal growth factor (EGF) signaling pathways is not defined. Here we present evidence that reexpression of ER protein by a clinically available HDAC inhibitor, suberoylanilide hydroxamic acid (SAHA or vorinostat), is coupled with loss of EGFR in ER-negative human breast cancer cells. Consistent with this observation, MDA-MB-231 cells, which are ER-negative and overexpress EGFR, that are engineered to express ER show a decrease in EGFR protein expression. Down-regulation of EGFR by SAHA results from attenuation of its mRNA stability. We also confirm that new protein synthesis is required for maintaining EGFR mRNA stability. Further experiments indicate that a decrease in EGFR abolished EGF-initiated signaling pathways including phosphorylated PAK1, p38MAPK and AKT. Thus, SAHA may not only reactivate silenced ER, but also simultaneously deplete EGFR expression. These data suggest that inhibition of HDAC is a promising epigenetic therapy for ER-negative human breast cancer.
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Affiliation(s)
- Qun Zhou
- The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, 1650 Orleans Street, CRBI Room 144, Baltimore, MD 21231, USA
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Role of protein phosphatases and mitochondria in the neuroprotective effects of estrogens. Front Neuroendocrinol 2009; 30:93-105. [PMID: 19410596 PMCID: PMC2835549 DOI: 10.1016/j.yfrne.2009.04.013] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Revised: 04/20/2009] [Accepted: 04/21/2009] [Indexed: 12/15/2022]
Abstract
In the present treatise, we provide evidence that the neuroprotective and mito-protective effects of estrogens are inexorably linked and involve the ability of estrogens to maintain mitochondrial function during neurotoxic stress. This is achieved by the induction of nuclear and mitochondrial gene expression, the maintenance of protein phosphatases levels in a manner that likely involves modulation of the phosphorylation state of signaling kinases and mitochondrial pro- and anti-apoptotic proteins, and the potent redox/antioxidant activity of estrogens. These estrogen actions are mediated through a combination of estrogens receptor (ER)-mediated effects on nuclear and mitochondrial transcription of protein vital to mitochondrial function, ER-mediated, non-genomic signaling and non-ER-mediated effects of estrogens on signaling and oxidative stress. Collectively, these multifaceted, coordinated action of estrogens leads to their potency in protecting neurons from a wide variety of acute insults as well as chronic neurodegenerative processes.
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Sunahori K, Juang YT, Tsokos GC. Methylation status of CpG islands flanking a cAMP response element motif on the protein phosphatase 2Ac alpha promoter determines CREB binding and activity. THE JOURNAL OF IMMUNOLOGY 2009; 182:1500-8. [PMID: 19155497 DOI: 10.4049/jimmunol.182.3.1500] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Protein phosphatase 2A (PP2A) is a major serine/threonine protein phosphatase in eukaryotic cells and is involved in many essential aspects of cell function. The catalytic subunit of the enzyme (PP2Ac), a part of the core enzyme, has two isoforms, alpha (PP2Ac alpha) and beta (PP2Ac beta), of which PP2Ac alpha is the major form expressed in vivo. Deregulation of PP2A expression has been linked to several diseases, but the mechanisms that control the expression of this enzyme are still unclear. We conducted experiments to decipher molecular mechanisms involved in the regulation of the PP2Ac alpha promoter in human primary T cells. After preparing serially truncated PP2Ac alpha promoter luciferase constructs, we found that the region stretching around 240 bases upstream from the translation initiation site was of functional significance and included a cAMP response element motif flanked by three GC boxes. Shift assays revealed that CREB/phosphorylated CREB and stable protein 1 could bind to the region. Furthermore, we demonstrated that methylation of deoxycytosine in the CpG islands limited binding of phosphorylated CREB and the activity of the PP2Ac alpha promoter. In contrast, the binding of stable protein 1 to a GC box within the core promoter region was not affected by DNA methylation. Primary T cells treated with 5-azacitidine, a DNA methyltransferase inhibitor, showed increased expression of PP2Ac alpha mRNA. We propose that conditions associated with hypomethylation of CpG islands, such as drug-induced lupus, permit increased PP2Ac expression.
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Affiliation(s)
- Katsue Sunahori
- Division of Rheumatology in Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
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Mo B, Callegari E, Telefont M, Renner KJ. Estrogen regulation of proteins in the rat ventromedial nucleus of the hypothalamus. J Proteome Res 2008; 7:5040-8. [PMID: 18841879 DOI: 10.1021/pr8005974] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The effects of estradiol (E2) on the expression of proteins in the pars lateralis of the ventromedial nucleus of the hypothalamus (VMNpl) in ovariectomized rats was studied using 2-dimensional gel electrophoresis followed by RPLC-nanoESI-MS/MS. E2 treatment resulted in the up-regulation of 29 identified proteins. Many of these proteins are implicated in the promotion of neuronal plasticity and signaling.
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Affiliation(s)
- Bing Mo
- Department of Biology and Neuroscience Group, University of South Dakota, Vermillion, South Daklota 57069, USA
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Yi KD, Simpkins JW. Protein phosphatase 1, protein phosphatase 2A, and calcineurin play a role in estrogen-mediated neuroprotection. Endocrinology 2008; 149:5235-43. [PMID: 18566123 PMCID: PMC2582922 DOI: 10.1210/en.2008-0610] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
It is becoming increasingly clear that protein phosphatases are important modulators of cellular function and that disruption of these proteins are involved in neurodegenerative disease processes. Serine/threonine protein phosphatases (PP) such as protein phosphatase PP1, PP2A, and calcineurin are involved in hyperphosphorylation of tau- as well as beta-amyloid-induced cell death. We have previously shown serine/threonine protein phosphatases to be involved in estrogen-mediated neuroprotection. The purpose of this study was to delineate the role of PP1, PP2A, and calcineurin in the mechanism of estrogen mediated neuroprotection against oxidative stress and excitotoxicity. Treatment with protein phosphatases inhibitor II, endothall, or cyclosporin A, which are specific inhibitors of PP1, PP2A, and calcineurin, respectively, did not have an effect on cell viability. However, in combination, these inhibitors adversely affected cell survival, which suggests the importance of serine/threonine protein phosphatases in maintenance of cellular function. Inhibitors of PP1, PP2A, and calcineurin attenuated the protective effects of estrogen against glutamate-induced -neurotoxicity but did not completely abrogate the estrogen-mediated protection. The attenuation of estrogen-induced neuroprotection was achieved through decrease in the activity of theses serine/threonine phosphatases without the concomitant decrease in protein expression. In an animal model, transient middle cerebral artery occlusion caused a 50% decrease in levels of PP1, PP2A, and PP2B ipsilateral to the lesion in a manner that was prevented by estradiol pretreatment. Therefore, we conclude that in the face of cytotoxic challenges in vitro and in vivo, estrogens maintain the function of PP1, PP2A, and calcineurin.
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Affiliation(s)
- Kun Don Yi
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas 76107, USA
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Yi KD, Cai ZY, Covey DF, Simpkins JW. Estrogen receptor-independent neuroprotection via protein phosphatase preservation and attenuation of persistent extracellular signal-regulated kinase 1/2 activation. J Pharmacol Exp Ther 2007; 324:1188-95. [PMID: 18089844 DOI: 10.1124/jpet.107.132308] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The mechanism of estrogen-mediated neuroprotection is not yet clear. Estrogens have a variety of modes of action, including transducing signaling events such as activation and/or suppression of the mitogen-activated protein kinase (MAPK) pathway. We have previously shown protein phosphatases to be involved in 17beta-estradiol-mediated neuroprotection. In the present study, we assessed the role of estrogen receptors (ERs) in estrogen-mediated neuroprotection from oxidative/excitotoxic stress and the consequential effects on MAPK signaling. Okadaic acid and calyculin A, nonspecific serine/threonine phosphatase inhibitors, were exposed to cells at various concentrations in the presence or absence of 17alpha-estradiol, the enantiomer of 17beta-estradiol, 2-(1-adamantyl)-3-hydroxyestra-1,3,5(10)-trien-17-one (ZYC3; non-ER-binding estrogen analog), and/or glutamate. All three compounds, which we have shown to have little or no binding to ERalpha and ERbeta, were protective against glutamate toxicity but not against okadaic acid and calyculin A toxicity. In addition, in the presence of effective concentrations of these inhibitors, the protective effects of these estrogen analogs were lost. Glutamate treatment caused a 50% decrease in levels of protein phosphatase 1 (PP1), protein phosphatase 2A (PP2A), and protein phosphatase 2B (calcineurin) (PP2B). Coadministration of ZYC3 with glutamate prevented the decreases in PP1, PP2A, and PP2B levels. Furthermore, glutamate treatment caused a persistent increase in phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 that corresponds with the decrease protein levels of serine/threonine phosphatases. ZYC3 blocked this persistent increase in ERK phosphorylation. These results suggest that estrogens protect cells against glutamate-induced oxidative stress through an ER-independent mediated mechanism that serves to preserve phosphatase activity in the face of oxidative insults, resulting in attenuation of the persistent phosphorylation of ERK associated with neuronal death.
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Affiliation(s)
- Kun Don Yi
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX 76107, USA
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29
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Ing NH, Massuto DA, Jaeger LA. Estradiol up-regulates AUF1p45 binding to stabilizing regions within the 3'-untranslated region of estrogen receptor alpha mRNA. J Biol Chem 2007; 283:1764-1772. [PMID: 18029355 DOI: 10.1074/jbc.m704745200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Estradiol up-regulates expression of the estrogen receptor alpha gene in the uterus by stabilizing estrogen receptor alpha mRNA. Previously, we defined two discrete minimal estradiol-modulated stability sequences (MEMSS) within the extensive 3'-untranslated region of estrogen receptor alpha mRNA with an in vitro stability assay using cytosolic extracts from sheep uterus. We report here that excess MEMSS RNA inhibited the enhanced stability of estrogen receptor alpha mRNA in extracts from estradiol-treated ewes compared with those from control ewes. Several estradiol-induced MEMSS-binding proteins were characterized by UV cross-linking in uterine extracts from ewes in a time course study (0, 8, 16, and 24 h after estradiol injection). The pattern of binding proteins changed at 16 h post-injection, concurrent with enhanced estrogen receptor alpha mRNA stability and the highest rate of accumulation of estrogen receptor alpha mRNA. The predominant MEMSS-binding protein induced by estradiol treatment was identified as AUF1 (A + U-rich RNA-binding factor 1) protein isoform p45 (a product of the heterogeneous nuclear ribonucleoprotein D gene). Immunoblot analysis indicated that only two of four AUF1 protein isoforms were present in the uterine cytosolic extracts and that estradiol treatment strongly increased the ratio of AUF1 isoforms p45 to p37. Nonphosphorylated recombinant AUF1p45 protected estrogen receptor alpha mRNA in vitro in a dose-dependent manner. These studies describe estrogenic induction of AUF1p45 binding to the estrogen receptor alpha mRNA as a molecular mechanism for post-transcriptional up-regulation of gene expression.
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Affiliation(s)
- Nancy H Ing
- Department of Animal Science, Texas A & M University, College Station, Texas 77843; Veterinary Integrative Biosciences, Texas A & M University, College Station, Texas 77843.
| | - Dana A Massuto
- Veterinary Integrative Biosciences, Texas A & M University, College Station, Texas 77843
| | - Laurie A Jaeger
- Veterinary Integrative Biosciences, Texas A & M University, College Station, Texas 77843
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Pryzbylkowski P, Obajimi O, Keen JC. Trichostatin A and 5 Aza-2' deoxycytidine decrease estrogen receptor mRNA stability in ER positive MCF7 cells through modulation of HuR. Breast Cancer Res Treat 2007; 111:15-25. [PMID: 17891453 DOI: 10.1007/s10549-007-9751-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2007] [Accepted: 09/06/2007] [Indexed: 12/23/2022]
Abstract
Trichostatin A (TSA) and 5-Aza 2'deoxycytidine (AZA), two well characterized pharmacologic inhibitors of histone deacetylation and DNA methylation, affect estrogen receptor alpha (ER) levels differently in ER-positive versus ER-negative breast cancer cell lines. Whereas pharmacologic inhibition of these epigenetic mechanisms results in re-expression and increased estrogen receptor alpha (ER) levels in ER-negative cells, treatment in ER-positive MCF7 cells results in decreased ER mRNA and protein levels. This decrease is dependent upon protein interaction with the ER 3'UTR. Actinomycin D studies showed a 37.5% reduction in ER mRNA stability from 4 to 1.5 h in AZA/TSA treated MCF7 cell lines; an effect not seen in 231ER + cells transfected with the ER coding region but lacking incorporation of the 3'UTR. AZA/TSA do not appear to directly interact with the 3'UTR but rather decrease stability through altered subcellular localization of the RNA binding protein, HuR. siRNA inhibition of HuR expression reduces both the steady-state and stability of ER mRNA, suggesting that HuR plays a critical role in the control of ER mRNA stability. Our data suggest that epigenetic modulators can alter stability through modulation of HuR subcellular distribution. Taken together, these data provide a novel anti-estrogenic mechanism for AZA and TSA in ER positive human breast cancer cells.
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Affiliation(s)
- Peter Pryzbylkowski
- Department of Medicine, Division of Molecular Medicine, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Rm 170 E&R Building, 401 Haddon Avenue, Camden, NJ 08103, USA
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31
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Winter SL, Bosnoyan-Collins L, Pinnaduwage D, Andrulis IL. The interaction of PP1 with BRCA1 and analysis of their expression in breast tumors. BMC Cancer 2007; 7:85. [PMID: 17511879 PMCID: PMC1906825 DOI: 10.1186/1471-2407-7-85] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2006] [Accepted: 05/19/2007] [Indexed: 11/18/2022] Open
Abstract
Background The breast cancer susceptibility gene, BRCA1, is implicated in multiple cellular processes including DNA repair, the transactivation of genes, and the ubiquitination of proteins; however its precise functions remain to be fully understood. Identification and characterization of BRCA1 protein interactions may help to further elucidate the function and regulation of BRCA1. Additionally, detection of changes in the expression levels of BRCA1 and its interacting proteins in primary human breast tumors may further illuminate their role in the development of breast cancer. Methods We performed a yeast two-hybrid study to identify proteins that interact with exon11 of BRCA1 and identified Protein Phosphatase 1β (PP1β), an isoform of the serine threonine phosphatase, PP1. GST-pull down and co-immunoprecipitation assays were performed to further characterize this interaction. Additionally, Real-Time PCR was utilized to determine the expression of BRCA1, PP1α, β and γ in primary human breast tumors and normal breast tissue to identify alterations in the expression of these genes in breast cancer. Results PP1 and BRCA1 co-immunoprecipitate and the region within BRCA1 as well as the specific PP1 interacting domain mediating this interaction were identified. Following mRNA expression analysis, we identified low levels of BRCA1 and variable levels of PP1α and β in primary sporadic human breast tumors. Furthermore, BRCA1, PP1β and PP1γ were significantly higher in normal tissue specimens (BRCA1 p = 0.01, PP1β: p = 0.03, PP1γ, p = 1.9 × 10-6) compared to sporadic breast tumor samples. Interestingly, we also identified that ER negative tumors are associated with low levels of PP1α expression. Conclusion The identification and characterization of the interaction of BRCA1 with PP1 and detection of changes in the expression of PP1 and genes encoding other BRCA1 associated proteins identifies important genetic pathways that may be significant to breast tumorigenesis. Alterations in the expression of genes, particularly phosphatases that operate in association with BRCA1, could negatively affect the function of BRCA1 or BRCA1 associated proteins, contributing to the development of breast cancer.
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Affiliation(s)
- Sherry L Winter
- Fred A. Litwin Centre for Cancer Genetics, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
- Department of Molecular and Medical Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Lucine Bosnoyan-Collins
- Fred A. Litwin Centre for Cancer Genetics, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Dushanthi Pinnaduwage
- Division of Epidemiology and Biostatistics, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Irene L Andrulis
- Fred A. Litwin Centre for Cancer Genetics, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
- Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada
- Department of Molecular and Medical Genetics, University of Toronto, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
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32
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Zaman G, Jessop HL, Muzylak M, De Souza RL, Pitsillides AA, Price JS, Lanyon LL. Osteocytes use estrogen receptor alpha to respond to strain but their ERalpha content is regulated by estrogen. J Bone Miner Res 2006; 21:1297-306. [PMID: 16869728 DOI: 10.1359/jbmr.060504] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
UNLABELLED The role of mechanical strain and estrogen status in regulating ERalpha levels in bone cells was studied in female rats. OVX is associated with decreased ERalpha protein expression/osteocyte, whereas habitual strain and artificial loading has only a small but positive effect, except on the ulna's medial surface, where artificial loading stimulates reversal of resorption to formation. INTRODUCTION Osteoporosis is the most widespread failure of bones' ability to match their architectural strength to their habitual load bearing. In men and women, the severity of bone loss is associated with bioavailability of estrogen. This association could result from the estrogen receptor (ER) involvement in bone cells' adaptive response to loading. MATERIALS AND METHODS In vivo semiquantitative analysis of the amount of ERalpha protein per osteocyte was performed in immuno-cytochemically stained sections from control and loaded rat ulna, as well as tibias of ovariectomy (OVX) and sham-operated female rats. In vitro, the effect of exogenous estrogen (10(-8) M) and mechanical strain (3400 microepsilon, 1 Hz, 600 cycles) on the expression of ERalpha mRNA levels was assessed in ROS 17/2.8 cells in monolayers using real-time PCR and ER promoter activity. ERalpha translocation in response to exogenous estrogen and mechanical strain was assessed in both ROS 17/2.8 and MLO-Y4 cells. RESULTS More than 90 percent of tibial osteocytes express ERalpha, the level/osteocyte being higher in cortical than cancellous bone. OVX is associated with decreased ERalpha protein expression/osteocyte, whereas in the ulna habitual strain and that caused by artificial loading had only a small but positive effect, except on the medial surface, where loading stimulates reversal of resorption to formation. In unstimulated osteocytes and osteoblasts in situ, and osteocyte-like and osteoblast-like cells in vitro, ERalpha is predominantly cytoplasmic. In vitro, both strain and estrogen stimulate transient ERalpha translocation to the nucleus and transient changes in ERalpha mRNA. Strain but not estrogen also induces discrete membrane localization of ERalpha. CONCLUSIONS Bone cells' responses to both strain and estrogen involve ERalpha, but only estrogen regulates its cellular concentration. This is consistent with the hypothesis that bone loss associated with estrogen deficiency is a consequence of reduction in ERalpha number/activity associated with lower estrogen concentration reducing the effectiveness of bone cells' anabolic response to strain.
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Affiliation(s)
- Gul Zaman
- Department of Basic Sciences, The Royal Veterinary College, University of London, London, United Kingdom.
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Huang Y, Keen JC, Pledgie A, Marton LJ, Zhu T, Sukumar S, Park BH, Blair B, Brenner K, Casero RA, Davidson NE. Polyamine analogues down-regulate estrogen receptor alpha expression in human breast cancer cells. J Biol Chem 2006; 281:19055-63. [PMID: 16679312 PMCID: PMC3623667 DOI: 10.1074/jbc.m600910200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The critical role of polyamines in cell growth has led to the development of a number of agents that interfere with polyamine metabolism including a novel class of polyamine analogues, oligoamines. Here we demonstrate that oligoamines specifically suppress the mRNA and protein expression of estrogen receptor alpha (ERalpha) and ERalpha target genes in ER-positive human breast cancer cell lines, whereas neither ERbeta nor other steroid hormonal receptors are affected by oligoamines. The constitutive expression of a cytomegalovirus promoter-driven exogenous ERalpha in ER-negative MDA-MB-231 human breast cancer cells was not altered by oligoamines, suggesting that oligoamines specifically suppress ERalpha transcription rather than affect mRNA or protein stability. Further analysis demonstrated that oligoamines disrupted the DNA binding activity of Sp1 transcription factor family members to an ERalpha minimal promoter element containing GC/CA-rich boxes. Treatment of MDA-MB-231 cells with the JNK-specific inhibitor SP600125 or expression of the c-Jun dominant negative inhibitor TAM67 blocked the oligoamine-activated JNK/c-Jun pathway and enhanced oligoamine-inhibited ERalpha expression, suggesting that AP-1 is a positive regulator of ERalpha expression and that oligoamine-activated JNK/AP-1 activity may antagonize the down-regulation of ERalpha induced by oligoamines. Taken together, these results suggest a novel antiestrogenic mechanism for specific polyamine analogues in human breast cancer cells.
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Affiliation(s)
- Yi Huang
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231
| | - Judith C. Keen
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231
| | - Allison Pledgie
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231
| | | | - Tao Zhu
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231
| | - Saraswati Sukumar
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231
| | - Ben Ho Park
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231
| | - Brian Blair
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231
| | - Keith Brenner
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231
| | - Robert A. Casero
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231
| | - Nancy E. Davidson
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231
- To whom correspondence should be addressed: Breast Cancer Program, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, 1650 Orleans St., Rm. 409, Baltimore, MD 21231. Tel.: 410-955-8489; Fax: 410-614-4073;
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Arnold HK, Sears RC. Protein phosphatase 2A regulatory subunit B56alpha associates with c-myc and negatively regulates c-myc accumulation. Mol Cell Biol 2006; 26:2832-44. [PMID: 16537924 PMCID: PMC1430332 DOI: 10.1128/mcb.26.7.2832-2844.2006] [Citation(s) in RCA: 204] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2005] [Revised: 10/07/2005] [Accepted: 01/10/2006] [Indexed: 01/05/2023] Open
Abstract
Protein phosphatase 2A (PP2A) plays a prominent role in controlling accumulation of the proto-oncoprotein c-Myc. PP2A mediates its effects on c-Myc by dephosphorylating a conserved residue that normally stabilizes c-Myc, and in this way, PP2A enhances c-Myc ubiquitin-mediated degradation. Stringent regulation of c-Myc levels is essential for normal cell function, as c-Myc overexpression can lead to cell transformation. Conversely, PP2A has tumor suppressor activity. Uncovering relevant PP2A holoenzymes for a particular target has been limited by the fact that cellular PP2A represents a large heterogeneous population of trimeric holoenzymes, composed of a conserved catalytic subunit and a structural subunit along with a variable regulatory subunit which directs the holoenzyme to a specific target. We now report the identification of a specific PP2A regulatory subunit, B56alpha, that selectively associates with the N terminus of c-Myc. B56alpha directs intact PP2A holoenzymes to c-Myc, resulting in a dramatic reduction in c-Myc levels. Inhibition of PP2A-B56alpha holoenzymes, using small hairpin RNA to knock down B56alpha, results in c-Myc overexpression, elevated levels of c-Myc serine 62 phosphorylation, and increased c-Myc function. These results uncover a new protein involved in regulating c-Myc expression and reveal a critical interconnection between a potent oncoprotein, c-Myc, and a well-documented tumor suppressor, PP2A.
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Affiliation(s)
- Hugh K Arnold
- Department of Molecular and Medical Genetics, Oregon Health & Sciences University, 3181 S.W. Sam Jackson Park Rd., L103A, Portland, Oregon 97239, USA
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Abukhdeir AM, Blair BG, Brenner K, Karakas B, Konishi H, Lim J, Sahasranaman V, Huang Y, Keen J, Davidson N, Vitolo MI, Bachman KE, Park BH. Physiologic estrogen receptor alpha signaling in non-tumorigenic human mammary epithelial cells. Breast Cancer Res Treat 2006; 99:23-33. [PMID: 16541319 DOI: 10.1007/s10549-006-9177-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2005] [Accepted: 01/22/2006] [Indexed: 11/25/2022]
Abstract
Currently, a number of breast cancer cell lines exist that serve as models for both estrogen receptor alpha (ERalpha) positive and ERalpha negative disease. Models are also available for pre-neoplastic breast epithelial cells that do not express ERalpha; however, there are no ideal systems for studying pre-neoplastic cells that are ERalpha positive. This has been largely due to the inability to establish an estrogen growth stimulated, non-tumorigenic breast epithelial cell line, as most human breast epithelial cells engineered to overexpress ERalpha have been found to be growth inhibited by estrogens. We have developed independently derived clones from the non-cancerous MCF-10A human breast cell line that express ERalpha and are growth stimulated by 17-beta-estradiol (E2) in the absence of epidermal growth factor (EGF), a cytokine normally required for MCF-10A cell proliferation. This effect is blocked by the selective estrogen receptor modulator (SERM), Tamoxifen and the selective estrogen receptor downregulator, ICI 182,780 (Faslodex, Fulvestrant). Exposure of these cells to EGF and E2 results in a growth inhibitory phenotype similar to previous reports. These data present a reconciling explanation for the previously described paradoxical effects of ERalpha overexpression, and provide a model for examining the carcinogenic effects of estrogens in non-tumorigenic human breast epithelial cells.
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Affiliation(s)
- Abde M Abukhdeir
- Department of Oncology, The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
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