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Choi Y, Pollack S. Significant Association of Estrogen Receptor-β Isoforms and Coactivators in Breast Cancer Subtypes. Curr Issues Mol Biol 2023; 45:2533-2548. [PMID: 36975536 PMCID: PMC10047005 DOI: 10.3390/cimb45030166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 03/08/2023] [Accepted: 03/10/2023] [Indexed: 03/22/2023] Open
Abstract
Nuclear receptor coregulators are the principal regulators of Estrogen Receptor (ER)-mediated transcription. ERβ, an ER subtype first identified in 1996, is associated with poor outcomes in breast cancer (BCa) subtypes, and the coexpression of the ERβ1 isoform and AIB-1 and TIF-2 coactivators in BCa-associated myofibroblasts is associated with high-grade BCa. We aimed to identify the specific coactivators that are involved in the progression of ERβ-expressing BCa. ERβ isoforms, coactivators, and prognostic markers were tested using standard immunohistochemistry. AIB-1, TIF-2, NF-kB, p-c-Jun, and/or cyclin D1 were differentially correlated with ERβ isoform expression in the BCa subtypes and subgroups. The coexpression of the ERβ5 and/or ERβ1 isoforms and the coactivators were found to be correlated with a high expression of P53, Ki-67, and Her2/neu and large-sized and/or high-grade tumors in BCa. Our study supports the notion that ERβ isoforms and coactivators seemingly coregulate the proliferation and progression of BCa and may provide insight into the potential therapeutic uses of the coactivators in BCa.
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Affiliation(s)
- Young Choi
- Department of Pathology, Yale School of Medicine, 434 Pine Grove Lane, Hartsdale, NY 10530, USA
- Correspondence:
| | - Simcha Pollack
- Department of Statistics, St. John’s University, New York, NY 11423, USA
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2
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Fluorescence resonance energy transfer-based nanomaterials for the sensing in biological systems. CHINESE CHEM LETT 2022. [DOI: 10.1016/j.cclet.2021.12.061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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3
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ERβ Isoforms Have Differential Clinical Significance in Breast Cancer Subtypes and Subgroups. Curr Issues Mol Biol 2022; 44:1564-1586. [PMID: 35723365 PMCID: PMC9164084 DOI: 10.3390/cimb44040107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 03/31/2022] [Accepted: 04/01/2022] [Indexed: 12/02/2022] Open
Abstract
ERβ, an ER subtype first identified in 1996, is highly expressed in different types of BCa including ERα-negative BCa and TNBC. Many studies on ERβ expression investigated mostly on ERβ1 protein expression in ERα-positive and ERα-negative BCa combined. The results are conflicting. This may be due to the complexity of ERβ isoforms, subject heterogeneity, and various study designs targeting different ERβ isoforms and either ERβ protein or mRNA expression, as well as to the lack of a standardized testing protocol. Herein, we simultaneously investigated both mRNA and protein expression of ERβ isoforms 1, 2, and 5 in different BCa subtypes and clinical characteristics. Patient samples (138) and breast cancer cell lines (BCC) reflecting different types of BCa were tested for ERα and ERβ mRNA expression using quantitative real-time PCR, as well as for protein expression of ERα, ERβ1, ERβ2, and ERβ5 isoforms, PR, HER2/neu, Ki-67, CK 5/6, and p53 using immunohistochemistry. Associations of ERβ isoform expression with clinical characteristics and overall survival (OS) were analyzed. ERβ1, 2, and 5 isoforms are differentially expressed in different BCa subtypes including ERα-negative and TNBC. Each ERβ isoform seemingly plays a distinct role and is associated with clinical tumor characteristics and patient outcomes. ERβ isoform expression is significantly associated with >15% Ki-67 positivity and poor prognostic markers, and it predicts poorer OS, mostly in the subgroups. High ERβ2 and 5 isoform expression in ERα-negative BCa and TNBC is predictive of poor OS. Further investigation of ERβ isoforms in a larger cohort of BCa subgroups is needed to evaluate the role of ERβ for the potential usefulness of ERβ as a prognostic and predictive marker and for therapeutic use. The inconsistent outcomes of ERβ isoform mRNA or protein expression in many studies suggest that the standardization of ERβ testing would facilitate the use of ERβ in a clinical setting.
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4
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Choi Y. Estrogen Receptor β Expression and Its Clinical Implication in Breast Cancers: Favorable or Unfavorable? J Breast Cancer 2022; 25:75-93. [PMID: 35380018 PMCID: PMC9065353 DOI: 10.4048/jbc.2022.25.e9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 11/18/2021] [Accepted: 02/03/2022] [Indexed: 11/30/2022] Open
Abstract
There are two estrogen receptor (ER) genes (ESR1/ERα and ESR2/ERβ) in humans. Of those. ERβ, the second ER isotype identified in 1996, is differentially expressed in different phenotypes and molecular subtypes of breast cancer (BCa), and is highly expressed in ERα-negative BCa and triple-negative BCa (TNBC). This review summarizes the potential clinical relevance of ERβ in BCa and the challenges associated with studies on the role of ERβ in BCa. The experimental and clinical studies evaluating clinical outcomes and associations with clinical characteristics and responses to endocrine therapy on targeting ERβ reviewed herein indicate that ERβ is a clinically important biomarker in BCa. The reviewed studies also suggest that each ERβ isoform has a distinct role in BCa subtypes and the potential of novel- targeted therapies in BCa, especially ERα-negative BCa and TNBC. However, the findings of many studies on ERβ are inconsistent, and the exact role of ERβ in BCa remains elusive; this may potentially be attributed to the complexity of ERβ isoforms, but also to the lack of standardized testing protocol. Thus, successful clinical application of ERβ requires the development of standardized, reproducible, and objective measurement methods for ERβ that can be widely and routinely applied in clinical setting.
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Affiliation(s)
- Young Choi
- Department of Pathology, Yale School of Medicine, Hartsdale, NY, USA
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5
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Shalabi MG, Abbas AM, Mills J, Kheirelseid MA, Elderdery AY. The Prognostic Value of Estrogen Receptor β Isoform With Correlation of Estrogen Receptor α Among Sudanese Breast Cancer Patients. BREAST CANCER-BASIC AND CLINICAL RESEARCH 2021; 15:1178223421998354. [PMID: 33716507 PMCID: PMC7917412 DOI: 10.1177/1178223421998354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Accepted: 02/02/2021] [Indexed: 11/16/2022]
Abstract
Two estrogen receptor isoforms (ERα and ERβ) have been characterized with variable and sometimes contrasting responses to estrogens, partially explained by different receptor signaling pathways in estrogen-sensitive tissues. This is a retrospective, descriptive, cross-sectional study, aiming to evaluate the expression pattern of ERβ, employing immunohistochemical techniques using specific monoclonal antibody for ERβ, to correlate its expression with that of ERα in a Sudanese population. Two-hundred and fifty formalin-fixed paraffin-wax-embedded breast tissue blocks were used in this study. Of these, 200 were taken from breast cancer patients ascertained as study cases, and the remaining 50 were noninvolved surgical margin considered as normal breast tissue. Receptor expression was demonstrated using immunohistochemical techniques. The immune expression of ERβ was detected in 57.5% of breast cancers. It was differentially expressed in breast tissues encompassing normal, noninvasive, as well as invasive carcinoma (P = .02). There was no evidence of a significant relationship between ERβ and ERα expression. Among the ERα-negative tumor, 60.4% expressed ERβ. The expression of ERβ among this subgroup was significantly associated with good clinicopathological parameters such as negative Her2/neu, lower grade, and negative lymph node metastasis (P = .002). This study concludes that ERβ was commonly expressed among Sudanese patients with breast cancer, either co-expressed with ERα or expressed alone. In the ERα-negative subgroup, it was associated with better tumor outcomes suggesting ERβ should be included in the diagnostic protocol as an independent marker for favorable prognosis.
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Affiliation(s)
- Manar G Shalabi
- Clinical Laboratory Sciences Department, College of Applied Medical Sciences, Jouf University, Sakakah, Saudi Arabia.,Medical Laboratory Sciences Department, Nahda College, Khartoum, Sudan
| | - Anass M Abbas
- Clinical Laboratory Sciences Department, College of Applied Medical Sciences, Jouf University, Sakakah, Saudi Arabia.,Medical Laboratory Program, School of Medicine, Alyarmouk Medical College, Khartoum, Sudan
| | - Jeremy Mills
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, UK
| | - Mohamed A Kheirelseid
- Pathology Department, Faculty of Medicine, Omdurman Islamic University, Omdurman, Sudan
| | - Abozer Y Elderdery
- Clinical Laboratory Sciences Department, College of Applied Medical Sciences, Jouf University, Sakakah, Saudi Arabia.,Faculty of Medical Laboratory Sciences, University of El Imam El Mahdi, Kosti, Sudan
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6
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Chinen AB, Guan CM, Ferrer JR, Barnaby SN, Merkel TJ, Mirkin CA. Nanoparticle Probes for the Detection of Cancer Biomarkers, Cells, and Tissues by Fluorescence. Chem Rev 2015; 115:10530-74. [PMID: 26313138 DOI: 10.1021/acs.chemrev.5b00321] [Citation(s) in RCA: 610] [Impact Index Per Article: 67.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Alyssa B Chinen
- Department of Chemistry, ‡Department of Chemical Engineering, §Department of Interdepartmental Biological Sciences, and ∥International Institute for Nanotechnology, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Chenxia M Guan
- Department of Chemistry, ‡Department of Chemical Engineering, §Department of Interdepartmental Biological Sciences, and ∥International Institute for Nanotechnology, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Jennifer R Ferrer
- Department of Chemistry, ‡Department of Chemical Engineering, §Department of Interdepartmental Biological Sciences, and ∥International Institute for Nanotechnology, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Stacey N Barnaby
- Department of Chemistry, ‡Department of Chemical Engineering, §Department of Interdepartmental Biological Sciences, and ∥International Institute for Nanotechnology, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Timothy J Merkel
- Department of Chemistry, ‡Department of Chemical Engineering, §Department of Interdepartmental Biological Sciences, and ∥International Institute for Nanotechnology, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Chad A Mirkin
- Department of Chemistry, ‡Department of Chemical Engineering, §Department of Interdepartmental Biological Sciences, and ∥International Institute for Nanotechnology, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States
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7
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Abstract
Despite over 15 years of research, the exact role, if any, played by estrogen receptor β (ERβ) in human breast cancer remains elusive. A large body of data both in vitro and in vivo supports its role as an antiproliferative, pro-apoptotic factor especially when co-expressed with ERα. However, there is a smaller body of data associating ERβ with growth and survival in breast cancer. In clinical studies and most often in cell culture studies, the pro-growth and pro-survival activity of ERβ occurs in ERα-negative breast cancer tissue and cells. This bi-faceted role of ERβ is discussed in this review.
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Affiliation(s)
- Etienne Leygue
- Department of Biochemistry and Medical Genetics, Manitoba Institute of Cell Biology, University of Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba, Canada R3E 0V9.
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Kang L, Guo Y, Zhang X, Meng J, Wang ZY. A positive cross-regulation of HER2 and ER-α36 controls ALDH1 positive breast cancer cells. J Steroid Biochem Mol Biol 2011; 127:262-8. [PMID: 21907803 PMCID: PMC3220752 DOI: 10.1016/j.jsbmb.2011.08.011] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 08/19/2011] [Accepted: 08/25/2011] [Indexed: 01/16/2023]
Abstract
Accumulating evidence supports the theory that breast cancer arises from a subpopulation of mammary stem/progenitor cell which posses the ability to self-renew. However, the involvement of estrogen signaling in regulation of breast cancer stem/progenitor cells has not been fully established, mainly because expression and function of ER-α in breast cancer stem cells remains controversial. Previously, our laboratory cloned a variant of ER-α, ER-α36, and found that ER-α36-mediated non-genomic estrogen signaling plays an important role in malignant growth of triple-negative breast cancer cells. In this study, we found that ER-α36 was highly expressed in ER-negative breast cancer SK-BR-3 cells and mediated non-genomic estrogen signaling such as activation of the MAPK/ERK signaling in these cells. Knock-down of ER-α36 expression in these cells using the shRNA method diminished their responsiveness to estrogen and significantly down-regulated HER2 expression. HER2 signaling activated ER-α36 transcription through an AP1 site in the ER-α36 promoter and ER-α36 physically interacted with HER2. We also found that ER-α36 is highly expressed in a subset of SK-BR-3 cells that was positive for ALDH1, a breast cancer stem cell marker, and knock-down of ER-α36 expression reduced the population of ALDH1 positive cells. Our results thus demonstrated that ER-α36 positively regulates HER2 expression and the population of ALDH1 positive breast cancer cells, and suggested that non-genomic estrogen signaling mediated by ER-α36 is involved in maintenance and regulation of breast cancer stem cells.
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Affiliation(s)
- Lianguo Kang
- Department of Medical Microbiology and Immunology, Creighton University Medical School, 2500 California Plaza, Omaha, NE 68178, USA
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9
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Leygue E, Murphy L. Comparative evaluation of ERα and ERβ significance in breast cancer: state of the art. Expert Rev Endocrinol Metab 2011; 6:333-343. [PMID: 30754114 DOI: 10.1586/eem.11.27] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Over 30 years of clinical data have unequivocally established estrogen receptor (ER)-α as a critical clinical biomarker and valid therapeutic target to fight breast cancer. However, ERα remains imperfect with respect to both of these activities, mainly because the mechanisms by which estrogens mediate their activity are far more complex than originally anticipated. The cloning of a second estrogen receptor, ERβ, has led to a full re-evaluation of our original view of the action of estrogen in breast tissues. Important challenges remain with respect to the design, selection and normalization of the most appropriate methods for assaying the expression and functionality of both receptors. Solving these challenges remains a priority in order to decide upon specific endocrine therapies and save patients who are still dying from a potentially curable disease.
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Affiliation(s)
- Etienne Leygue
- a Department of Biochemistry and Medical Genetics, Manitoba Institute of Cell Biology, University of Manitoba, 675 McDermot Ave, Winnipeg, Manitoba, R3E 0V9, Canada
| | - Leigh Murphy
- a Department of Biochemistry and Medical Genetics, Manitoba Institute of Cell Biology, University of Manitoba, 675 McDermot Ave, Winnipeg, Manitoba, R3E 0V9, Canada
- b
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10
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Estrogen receptor-beta expression in invasive breast cancer in relation to molecular phenotype: results from the Nurses' Health Study. Mod Pathol 2010; 23:197-204. [PMID: 19898422 PMCID: PMC3055924 DOI: 10.1038/modpathol.2009.158] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The expression of estrogen receptor-alpha (ER-alpha) and related genes has emerged as one of the major determinants of molecular classification of invasive breast cancers. Expression of a second ER, estrogen receptor-beta (ER-beta), has not been previously evaluated in a large population-based study. Therefore, we examined ER-beta expression in a large population of women with breast cancer to assess its relationship to molecular categories of invasive breast cancer. We constructed tissue microarrays from paraffin blocks of 3093 breast cancers that developed in women enrolled in the Nurses' Health Study. Tissue microarray sections were immunostained for ER-alpha, progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), cytokeratin 5/6, epidermal growth factor receptor (EGFR) and with a monoclonal antibody to ER-beta. Cancers were categorized as luminal A (ER-alpha+ and/or PR+ and HER2-); luminal B (ER-alpha+ and/or PR+ and HER2+); HER2 (ER-alpha- and PR- and HER2+); and basal-like (ER-alpha-, PR-, HER2- and EGFR or cytokeratin 5/6+). The relationship between expression of ER-beta and molecular class of invasive breast cancer was analyzed. Overall, 68% of breast carcinomas were ER-beta+. Expression of ER-beta was significantly associated with expression of ER-alpha (P<0.0001) and PR (P<0.0001), and was inversely related to expression of HER2 (P=0.004), CK5/6 (P=0.02) and EGFR (P=0.006). Among 2170 invasive cancers with complete immunophenotypic data, 73% were luminal A, 5% luminal B, 6 % HER2 and 11% basal-like. ER-beta expression was significantly related to molecular category (P<0.0001) and was more common in luminal A (72% of cases) and B (68% of cases) than in HER2 or basal-like types. However, despite their being defined by the absence of ER-alpha expression, 55% of HER2-type and 60% of basal-like cancers showed expression of ER-beta. The role of ER-beta in the development and progression of breast cancers defined by lack of expression of ER-alpha merits further investigation.
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11
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Abdou AG, Aiad HAS, Sultan SM. pS2 (TFF1) expression in prostate carcinoma: correlation with steroid receptor status. APMIS 2009; 116:961-71. [PMID: 19132993 DOI: 10.1111/j.1600-0463.2008.01009.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
pS2 or TFF1 is a member of the trefoil factor family, which is distributed throughout the gastrointestinal tract in both normal and diseased tissues. It is also considered to be one of the major estrogen-regulated proteins and an indicator of estrogen receptor (ER) functionality. pS2 has previously been investigated in benign and malignant prostate lesions with little information about its relationship to steroid receptor status. Our purpose was to correlate pS2 expression with steroid receptor status (ER alpha and progesterone receptor (PR)) and other pathologic variables in prostate carcinoma. 15 benign prostate hyperplasia (BPH) and 47 prostate carcinoma cases were investigated by means of immunohistochemistry for pS2, ER and PR expression. 80% of BPH showed pS2 cytoplasmic immunoreactivity in hyperplastic acini and about half of these cases also exhibited nuclear staining decorating basal or both basal and luminal nuclei. pS2 was highly expressed in prostate carcinoma (91.4%) with both cytoplasmic and nuclear patterns of staining. The latter pattern was significantly associated with carcinoma having a low Gleason score (p=0.02). pS2 lacked any significant correlation with steroid receptor status, stage or grade. Univariate survival analysis revealed a significant impact of stage (p=0.03) and nodal status (p<0.0001) on patient outcome. The diagnostic value of pS2 expression in prostate carcinoma validated 74.19% accuracy, 91.48% sensitivity and 78.18% positive predictive value. The high sensitivity of pS2 expression in prostate carcinoma could make it a suitable marker for diagnosis of prostate carcinoma, especially in metastatic cases of unknown origin. The absence of correlation and dissimilarity in immunolocalization between pS2 and ER alpha leads to the assumption that ER alpha could not be the regulatory protein for pS2 and may raise questions about the functionality of ER alpha in prostate. The nuclear pattern of pS2 immunoreactivity either in benign or malignant prostatic lesions is similar to the published data on ER beta distribution and could also identify a subset of carcinoma patients with a favorable prognosis.
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Affiliation(s)
- Asmaa Gaber Abdou
- Department of Pathology, Faculty of Medicine, Menofiya University, Shebein Elkom, Egypt.
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12
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Park MH, Ryu HS, Ro HW, Cho JS, Yoon JH, Jegal YJ, Kim JH, Lee JS, Park CS. The Clinical Significance of the Estrogen Receptor β Expression for Endocrine Therapy in Patients with ERα-negative and Progesterone Receptor-positive Breast Carcinoma. J Breast Cancer 2009. [DOI: 10.4048/jbc.2009.12.3.156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
- Min Ho Park
- Department of Surgery, Chonnam National University Hwasun Hospital, Gwangju, Korea
| | - Hee Seon Ryu
- Department of Surgery, Chonnam National University Hwasun Hospital, Gwangju, Korea
| | - Hye Won Ro
- Department of Surgery, Chonnam National University Hwasun Hospital, Gwangju, Korea
| | - Jin Seong Cho
- Department of Surgery, Chonnam National University Hwasun Hospital, Gwangju, Korea
| | - Jung Han Yoon
- Department of Surgery, Chonnam National University Hwasun Hospital, Gwangju, Korea
| | - Young Jong Jegal
- Department of Surgery, Chonnam National University Hwasun Hospital, Gwangju, Korea
| | - Jo Heon Kim
- Department of Pathology, Chonnam National University Hwasun Hospital, Gwangju, Korea
| | - Ji Shin Lee
- Department of Pathology, Chonnam National University Hwasun Hospital, Gwangju, Korea
| | - Chang Soo Park
- Department of Pathology, Chonnam National University Hwasun Hospital, Gwangju, Korea
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13
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Speirs V, Shaaban AM. Role of ERβ in Clinical Breast Cancer. Cancer Treat Res 2009; 147:1-20. [PMID: 21461830 DOI: 10.1007/978-0-387-09463-2_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Valerie Speirs
- Section of Pathology and Tumor Biology, Leeds Institute of Molecular Medicine, University of Leeds, Wellcome Trust Brenner Building, St James's University Hospital, Leeds, LS9 7TF, UK,
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14
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Ooi SM, Vivian JB, Cohen RJ. The use of the Ki-67 marker in the pathological diagnosis of the epithelioid variant of renal angiomyolipoma. Int Urol Nephrol 2008; 41:559-65. [PMID: 18839327 DOI: 10.1007/s11255-008-9473-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2008] [Accepted: 09/03/2008] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Epithelioid angiomyolipoma (EAML) is a rare malignant variant of renal angiomyolipoma (AML). There were 34 cases of EAML reported in 25 studies (including this present study) over the past decade. About 68% were females and 32% males. The mean age was 40.1 years, 53% developed metastatic disease after nephrectomy, and eight patients had TSC. All cases are reported positive when stained with HMB-45 which also labels all classical AML. This study evaluates the use of Ki-67 (proliferation marker) in the pathological diagnosis of EAML and distinction from classical AML. METHOD Immunohistochemical reactions for Ki-67 were generated on multiple representative blocks of tissue obtained from two cases of HMB-45 positive EAML and four cases of classic AML and the percentage of positively staining cells estimated. RESULTS Both cases of EAML were strongly positive for Ki-67 while all four classic AML were completely negative. CONCLUSION The Ki67 is a useful marker in which distinguishes the malignant epithelioid variant of AML from classic AML.
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Affiliation(s)
- Sue Min Ooi
- Department of Urology, Royal Perth Hospital, Perth, Australia.
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15
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Fox EM, Davis RJ, Shupnik MA. ERbeta in breast cancer--onlooker, passive player, or active protector? Steroids 2008; 73:1039-51. [PMID: 18501937 PMCID: PMC2583259 DOI: 10.1016/j.steroids.2008.04.006] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2007] [Revised: 04/08/2008] [Accepted: 04/09/2008] [Indexed: 02/07/2023]
Abstract
The role of estrogen exposure in breast cancer risk is well-documented, and both estrogen synthesis and actions through the estrogen receptor (ER) have been targeted by therapies to control hormone-dependent breast cancer. The discovery of a second ER form and its therapeutic implications sparked great interest. Both the original ERalpha and the more recently identified ERbeta subtypes bind and respond similarly to many physiological and pharmacological ligands. However, differences in phytoestrogen binding have been noted, and subtype-specific ligands have been developed. Cell-based assays show that ERbeta and its variants are generally less active on gene transcription than ERalpha, and may influence ERalpha activity; however, both gene- and cell-specific responses occur, and nongenomic activities are less well explored. Specific ligands, and methods to disrupt or eliminate receptor subtype expression in animal and cell models, demonstrate that the ERs have both overlapping and distinct biological functions. Overall, in cell-based studies, ERalpha appears to play a predominant role in cell proliferation, and ERbeta is suggested to be antiproliferative. The potential for distinct populations of breast tumors to be identified based on ER subtype expression, and to exhibit distinct clinical behaviors, is of greatest interest. Several studies suggest that the majority of ER-positive tumors contain both subtypes, but that some tumors contain only ERbeta and may have distinct clinical behaviors and responses. Expression of ERbeta together with ERalpha favors positive responses to endocrine therapy in most studies, and additional studies to determine if the addition of ERbeta to ERalpha as a tumor marker is of clinical benefit are warranted. In contrast, the positive association between ERbeta and HER2 expression in high-grade ERalpha-negative breast cancer does not favor positive responses to endocrine therapy. Expression of ERbeta in specific clinical subpopulations, and the potential for therapies targeting ERbeta specifically, is discussed.
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Affiliation(s)
- Emily M. Fox
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22903
| | - Rebecca J. Davis
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22903
| | - Margaret A. Shupnik
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22903
- Department of Medicine, University of Virginia School of Medicine, Charlottesville, VA 22903
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16
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Skliris GP, Leygue E, Watson PH, Murphy LC. Estrogen receptor alpha negative breast cancer patients: estrogen receptor beta as a therapeutic target. J Steroid Biochem Mol Biol 2008; 109:1-10. [PMID: 18243688 DOI: 10.1016/j.jsbmb.2007.12.010] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Clinical management of breast cancer is increasingly guided by assessment of tumor phenotypic parameters. One of these is estrogen receptor (ER) status, currently defined by ERalpha expression. However with the discovery of a second ER, ERbeta and its variant isoforms, the definition of ER status is potentially more complex. In breast tumors there are two ERbeta expression cohorts. One where ERbeta is co-expressed with ERalpha and the other expressing ERbeta alone. In the latter subgroup of currently defined ER negative patients ERbeta has the potential to be a therapeutic target. Characterization of the nature and role of ERbeta in ERalpha negative tumors is essentially unexplored but available data suggest that the role of ERbeta may be different when co-expressed with ERalpha and when expressed alone. This review summarizes available data and explores the possibility that ERbeta signaling may be a therapeutic target in these tumors. Evidence so far supports the idea that the role of ERbeta in breast cancer is different in ERalpha negative compared to ERalpha positive tumors. However, cohort size and numbers of independent studies are small to date, and more studies are needed with better standardization of antibodies and protocols. Also, the ability to determine the role of ERbeta in ERalpha negative breast cancer and therefore assess ERbeta signaling pathways as therapeutic targets would be greatly facilitated by identification of specific downstream markers of ERbeta activity in breast cancer.
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Affiliation(s)
- George P Skliris
- Manitoba Institute of Cell Biology, Department of Biochemistry & Medical Genetics, University of Manitoba, Winnipeg, Manitoba, Canada R3E OV9
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17
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Yang XR, Pfeiffer RM, Garcia-Closas M, Rimm DL, Lissowska J, Brinton LA, Peplonska B, Hewitt SM, Cartun RW, Mandich D, Sasano H, Evans DB, Sutter TR, Sherman ME. Hormonal markers in breast cancer: coexpression, relationship with pathologic characteristics, and risk factor associations in a population-based study. Cancer Res 2007; 67:10608-17. [PMID: 17968031 DOI: 10.1158/0008-5472.can-07-2142] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The objective of this study was to evaluate the coexpression patterns of hormonal markers in breast cancer tissue and their relationship with pathologic characteristics and epidemiologic risk factors. We evaluated the expression of 17 markers by immunohistochemistry in 842 invasive breast carcinomas collected in a population-based case-control study conducted in Poland. Based on marker correlations, factor analysis identified four major coexpression patterns (factors): "nuclear receptor factor" [estrogen receptor (ER)-alpha, progesterone receptor, androgen receptor, cyclin D1, and aromatase], "estrogen metabolism/ER-beta factor" (ER-beta, peroxisome proliferator-activated receptor-gamma, steroid sulfatase, estrogen sulfonotransferase, and cytochrome P450 1B1), "HER2 factor" (human epidermal growth factor receptor 2, E-cadherin, cyclooxygenase-2, aromatase, steroid sulfatase), and "proliferation factor" (cytokeratin 5, cytokeratin 5/6, epidermal growth factor receptor, P53). Three of these factors corresponded to molecular subtypes previously defined by expression profiling; however, the estrogen metabolism/ER-beta factor seemed to be distinctive. High scores for this factor were associated with high tumor grade (P heterogeneity = 0.02), younger age at menarche (P heterogeneity = 0.04), lower current body mass index among premenopausal women (P heterogeneity = 0.01), and older age at menopause (P heterogeneity = 0.04). High scores for the proliferation factor were also associated with early menarche (P heterogeneity < 0.0001), and in contrast to the estrogen metabolism/ER-beta factor, higher current body mass index among premenopausal women (P heterogeneity = 0.03). Our analysis of hormonal pathway markers independently confirmed several previously defined molecular subtypes identified by gene expression profiling and augmented these findings by suggesting the existence of additional relationships related to ER-beta and enzymes involved in hormone metabolism.
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Affiliation(s)
- Xiaohong R Yang
- Genetic Epidemiology Branch, Division of Cancer Epidemiology & Genetics, National Cancer Institute, NIH, Bethesda, MD 20892-7236, USA.
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18
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Bartlett JMS, Ellis IO, Dowsett M, Mallon EA, Cameron DA, Johnston S, Hall E, A'Hern R, Peckitt C, Bliss JM, Johnson L, Barrett-Lee P, Ellis P. Human epidermal growth factor receptor 2 status correlates with lymph node involvement in patients with estrogen receptor (ER) negative, but with grade in those with ER-positive early-stage breast cancer suitable for cytotoxic chemotherapy. J Clin Oncol 2007; 25:4423-30. [PMID: 17906205 DOI: 10.1200/jco.2007.11.0973] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
PURPOSE Human epidermal growth factor receptor 2 (HER-2) expression is associated with increased risk of high-grade disease, nodal metastasis, and absence of estrogen receptors (ERs) in early breast cancer. We tested interactions between ER and HER-2 to determine if they may modulate breast cancer nodal metastasis and proliferation. PATIENTS AND METHODS Tumors from the Cancer Research UK Taxotere as Adjuvant Chemotherapy phase III trial were tested for HER-2 using current diagnostic procedures. ER status, progesterone status, clinicopathologic characteristics, and patient age were included in a logistic regression analysis to identify associations with HER-2 status (positive v negative). RESULTS A total of 841 (23.6%) of 3,565 samples were HER-2 positive (3+ by immunohistochemistry or positive by fluorescent in situ hybridization). ER-negative tumors were more likely to be HER-2 positive than were ER-positive tumors (odds ratio [OR] = 1.87, ER negative v ER positive; P < .001). For ER-positive tumors, risk of HER-2 positivity increased by grade (OR = 7.6, grade 3 v grade 1; P < .001) but not nodal status (OR = 1.3, four or more positive nodes v node negative; P = .08). Conversely, ER negative node-positive tumors were markedly more frequently HER-2 positive than node-negative cases (OR = 3.05, four or more positive nodes v node negative; P < .001) but independent of grade (OR = 0.82, grade 3 v grade 1; P = .76). CONCLUSION In early breast cancer patients selected for cytotoxic chemotherapy, we identified significant interactions between HER-2 and ER expression that correlate with tumor pathology. In ER-positive breast cancers, HER-2 expression correlates with grade, not nodal metastasis. In ER-negative breast cancers, HER-2 expression correlates with increased nodal positivity, not grade. ER and HER-2 expression may modify tumor pathology via ER/HER-2-mediated cross talk.
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Affiliation(s)
- John M S Bartlett
- Endocrine Cancer Research Group, Edinburgh University Cancer Research Centre, Western General Hospital, Edinburgh, United Kingdom.
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19
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Mackay A, Urruticoechea A, Dixon JM, Dexter T, Fenwick K, Ashworth A, Drury S, Larionov A, Young O, White S, Miller WR, Evans DB, Dowsett M. Molecular response to aromatase inhibitor treatment in primary breast cancer. Breast Cancer Res 2007; 9:R37. [PMID: 17555561 PMCID: PMC1929101 DOI: 10.1186/bcr1732] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2007] [Revised: 04/26/2007] [Accepted: 06/07/2007] [Indexed: 11/10/2022] Open
Abstract
Background Aromatase inhibitors such as anastrozole and letrozole are highly effective suppressants of estrogen synthesis in postmenopausal women and are the most effective endocrine treatments for hormone receptor positive breast cancer in such women. Little is known of the molecular effects of these agents on human breast carcinomas in vivo. Methods We randomly assigned primary estrogen receptor positive breast cancer patients to treatment with anastrozole or letrozole for 2 weeks before surgery. Expression profiling using cDNA arrays was conducted on pretreatment and post-treatment biopsies. Sample pairs from 34 patients provided sufficient RNA for analysis. Results Profound changes in gene expression were seen with both aromatase inhibitors, including many classical estrogen-dependent genes such as TFF1, CCND1, PDZK1 and AGR2, but also many other genes that are likely to represent secondary responses; decrease in the expression of proliferation-related genes were particularly prominent. Many upregulated genes are involved in extracellular matrix remodelling, including collagens and members of the small leucine-rich proteoglycan family (LUM, DCN, and ASPN). No significant differences were seen between letrozole and anastrozole in terms of molecular effects. The gene changes were integrated into a Global Index of Dependence on Estrogen (GIDE), which enumerates the genes changing by at least twofold with therapy. The GIDE varied markedly between tumours and related significantly to pretreatment levels of HER2 and changes in immunohistochemically detected Ki67. Conclusion Our findings identify the transcriptional signatures associated with aromatase inhibitor treatment of primary breast tumours. Larger datasets using this approach should enable identification of estrogen-dependent molecular changes, which are the determinants of benefit or resistance to endocrine therapy.
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Affiliation(s)
- Alan Mackay
- The Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, Fulham Road, London, SW3 6JB, UK
| | - Ander Urruticoechea
- Academic Department of Biochemistry, Royal Marsden Hospital, Fulham Road, London, SW3 6JJ, UK
| | | | - Tim Dexter
- The Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, Fulham Road, London, SW3 6JB, UK
| | - Kerry Fenwick
- The Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, Fulham Road, London, SW3 6JB, UK
| | - Alan Ashworth
- The Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, Fulham Road, London, SW3 6JB, UK
| | - Suzanne Drury
- Academic Department of Biochemistry, Royal Marsden Hospital, Fulham Road, London, SW3 6JJ, UK
| | - Alexey Larionov
- The Edinburgh Breast Unit, Western General Hospital, Edinburgh, EH4 2XU, UK
| | - Oliver Young
- The Edinburgh Breast Unit, Western General Hospital, Edinburgh, EH4 2XU, UK
| | - Sharon White
- The Edinburgh Breast Unit, Western General Hospital, Edinburgh, EH4 2XU, UK
| | - William R Miller
- The Edinburgh Breast Unit, Western General Hospital, Edinburgh, EH4 2XU, UK
| | | | - Mitch Dowsett
- The Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, Fulham Road, London, SW3 6JB, UK
- Academic Department of Biochemistry, Royal Marsden Hospital, Fulham Road, London, SW3 6JJ, UK
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20
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Umekita Y, Souda M, Ohi Y, Sagara Y, Rai Y, Takahama T, Yoshida H. Expression of wild-type estrogen receptor beta protein in human breast cancer: specific correlation with HER2/neu overexpression. Pathol Int 2006; 56:423-7. [PMID: 16872435 DOI: 10.1111/j.1440-1827.2006.01983.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Expression of estrogen receptor beta (ERbeta) protein in human breast cancer and correlation with clinicopathological factors have been reported by many investigators, but many of them used ERbeta antibodies that react with both wild-type ERbeta (ERbetawt) and splicing variant isoform. Therefore, the frequency and correlation with clinicopathological factors of ERbetawt expression remain to be established. In the present study a monoclonal antibody EMR02, specific for ERbetawt, was used in formalin-fixed paraffin-embedded sections from 225 female primary breast cancer patients diagnosed as having invasive ductal carcinoma. Expression of ERalpha, progesterone receptor (PgR) and HER2/neu were also investigated by immunohistochemistry. For ERbetawt, ERalpha and PgR, positivity was defined as nuclear staining in >10% of the cancer cells. HER2/neu overexpression was defined as a Hercep test score 3+. Positivity for ERbetawt, ERalpha, PgR and HER2/neu overexpression was 55%, 74%, 61% and 25%, respectively. The expression of ERbetawt had a positive correlation with ERalpha (P=0.018) and PgR (P=0.02). There was significant positive correlation between ERbetawt expression and HER2/neu overexpression (P<0.0001). According to multivariate logistic regression analysis the most significant association was between ERbetawt expression and HER2/neu overexpression (P<0.0001). These results suggest that clinical significances of ERbetawt expression in human breast cancer patients may be more complex.
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MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Antibodies, Monoclonal
- Antibodies, Monoclonal, Humanized
- Biomarkers, Tumor/metabolism
- Breast Neoplasms/metabolism
- Breast Neoplasms/pathology
- Breast Neoplasms/surgery
- Carcinoma, Ductal, Breast/metabolism
- Carcinoma, Ductal, Breast/secondary
- Carcinoma, Ductal, Breast/surgery
- Cell Nucleus/metabolism
- Cell Nucleus/pathology
- Estrogen Receptor beta/metabolism
- Female
- Humans
- Immunoenzyme Techniques
- Mammary Glands, Human/metabolism
- Middle Aged
- Neoplasm Staging
- Reagent Kits, Diagnostic
- Receptor, ErbB-2/metabolism
- Receptors, Progesterone/metabolism
- Trastuzumab
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Affiliation(s)
- Yoshihisa Umekita
- Department of Tumor Pathology, Field of Oncology, Kagoshima University Graduate School of Medical and Dental Sciences, and Sagara Hospital, Kagoshima, Japan.
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21
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Tavera-Mendoza LE, Mader S, White JH. Genome-wide approaches for identification of nuclear receptor target genes. NUCLEAR RECEPTOR SIGNALING 2006; 4:e018. [PMID: 16862224 PMCID: PMC1513072 DOI: 10.1621/nrs.04018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2005] [Accepted: 04/06/2006] [Indexed: 11/20/2022]
Abstract
Large-scale genomics analyses have grown by leaps and bounds with the rapid advances in high throughput DNA sequencing and synthesis techniques. Nuclear receptor signaling is ideally suited to genomics studies because receptors function as ligand-regulated gene switches. This review will survey the strengths and limitations of three major classes of high throughput techniques widely used in the nuclear receptor field to characterize ligand-dependent gene regulation: expression profiling studies (microarrays, SAGE and related techniques), chromatin immunoprecipitation followed by microarray (ChIP-on-chip), and genome-wide in silico hormone response element screens. We will discuss each technique, and how each has contributed to our understanding of nuclear receptor signaling.
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22
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Garofalo C, Koda M, Cascio S, Sulkowska M, Kanczuga-Koda L, Golaszewska J, Russo A, Sulkowski S, Surmacz E. Increased expression of leptin and the leptin receptor as a marker of breast cancer progression: possible role of obesity-related stimuli. Clin Cancer Res 2006; 12:1447-53. [PMID: 16533767 DOI: 10.1158/1078-0432.ccr-05-1913] [Citation(s) in RCA: 265] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
PURPOSE Recent in vitro studies suggested that the autocrine leptin loop might contribute to breast cancer development by enhancing cell growth and survival. To evaluate whether the leptin system could become a target in breast cancer therapy, we examined the expression of leptin and its receptor (ObR) in primary and metastatic breast cancer and noncancer mammary epithelium. We also studied whether the expression of leptin/ObR in breast cancer can be induced by obesity-related stimuli, such as elevated levels of insulin, insulin-like growth factor-I (IGF-I), estradiol, or hypoxic conditions. EXPERIMENTAL DESIGN The expression of leptin and ObR was examined by immunohistochemistry in 148 primary breast cancers and 66 breast cancer metastases as well as in 90 benign mammary lesions. The effects of insulin, IGF-I, estradiol, and hypoxia on leptin and ObR mRNA expression were assessed by reverse transcription-PCR in MCF-7 and MDA-MB-231 breast cancer cell lines. RESULTS Leptin and ObR were significantly overexpressed in primary and metastatic breast cancer relative to noncancer tissues. In primary tumors, leptin positively correlated with ObR, and both biomarkers were most abundant in G3 tumors. The expression of leptin mRNA was enhanced by insulin and hypoxia in MCF-7 and MDA-MB-231 cells, whereas IGF-I and estradiol stimulated leptin mRNA only in MCF-7 cells. ObR mRNA was induced by insulin, IGF-I, and estradiol in MCF-7 cells and by insulin and hypoxia in MDA-MB-231 cells. CONCLUSIONS Leptin and ObR are overexpressed in breast cancer, possibly due to hypoxia and/or overexposure of cells to insulin, IGF-I, and/or estradiol.
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MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Biomarkers, Tumor/metabolism
- Breast/metabolism
- Breast/pathology
- Breast Neoplasms/genetics
- Breast Neoplasms/metabolism
- Breast Neoplasms/pathology
- Carcinoma, Ductal, Breast/genetics
- Carcinoma, Ductal, Breast/metabolism
- Carcinoma, Ductal, Breast/pathology
- Case-Control Studies
- Cell Hypoxia
- Disease Progression
- Estradiol/pharmacology
- Female
- Humans
- Insulin/pharmacology
- Insulin-Like Growth Factor I/pharmacology
- Leptin/genetics
- Leptin/metabolism
- Middle Aged
- Neoplasms/genetics
- Neoplasms/metabolism
- Neoplasms/pathology
- Obesity/complications
- Obesity/metabolism
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Receptors, Leptin
- Reverse Transcriptase Polymerase Chain Reaction
- Tumor Cells, Cultured
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Affiliation(s)
- Cecilia Garofalo
- Sbarro Institute for Cancer Research and Molecular Medicine, College of Science and Technology, Temple University, Philadelphia, Pennsylvania 19122, USA
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23
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Jarzabek K, Koda M, Kozlowski L, Mittre H, Sulkowski S, Kottler ML, Wolczynski S. Distinct mRNA, protein expression patterns and distribution of oestrogen receptors α and β in human primary breast cancer: Correlation with proliferation marker Ki-67 and clinicopathological factors. Eur J Cancer 2005; 41:2924-34. [PMID: 16289616 DOI: 10.1016/j.ejca.2005.09.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2005] [Revised: 08/23/2005] [Accepted: 09/02/2005] [Indexed: 11/30/2022]
Abstract
To elucidate the molecular profile of oestrogen receptors alpha and beta (ERalpha, ERbeta) we studied ERalpha and ERbeta expression at the mRNA and protein levels using real-time polymerase chain reaction (RT-PCR), Western blot analysis and immunohistochemical (IHC) methods in 41 primary breast cancers and surrounding tissues. ERalpha mRNA and ERbeta mRNA were detected in all of the breast cancer and normal matched tissues analysed. ERalpha mRNA levels showed greater diversity than ERbeta mRNA levels and the range of amount of ERbeta transcripts was far smaller than that of ERalpha. At the protein level, the percentage of ERalpha- or ERbeta-positive cases changed. Seventy percent of the tumours studied produced full-length 65 kDa ERalpha protein in Western blot analysis and 67% of assessed cases were positive in IHC. Full-length 57 kDa ERbeta protein was detected by Western blotting in 97% of analysed breast cancers, while 67% were ERbeta-positive using IHC. ERalpha was localised in the nucleus, while cytoplasmic and perinuclear localisation of ERbeta was observed in normal as well as in breast cancer cells. The amount of ERalpha (but not ERbeta) increased with age. The expression of ERalpha correlated positively with progesterone receptor and negatively with proliferation marker Ki-67. These results confirm the previous observations that the lack of ERalpha protein expression is not due to lack of ERalpha gene expression or methylation of ERalpha promoter, but due to post-transcriptional or post-translational mechanisms. Our investigation also suggests that ERalpha is more dysregulated in breast cancer, and thereby ERbeta is more tightly regulated in the tumour.
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Affiliation(s)
- Katarzyna Jarzabek
- Department of Gynaecological Endocrinology, Medical University of Bialystok, Sklodowskiej 24A, Bialystok, Poland.
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