101
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Esparís-Ogando A, Ocaña A, Rodríguez-Barrueco R, Ferreira L, Borges J, Pandiella A. Synergic antitumoral effect of an IGF-IR inhibitor and trastuzumab on HER2-overexpressing breast cancer cells. Ann Oncol 2008; 19:1860-9. [PMID: 18641009 DOI: 10.1093/annonc/mdn406] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Receptor tyrosine kinases play an important role in breast cancer. One of them, the type I insulin-like growth factor, has been linked to resistance to trastuzumab (Herceptin), an agent that targets human epidermal growth factor receptor 2. Here, we show that the insulin-like growth factor-I receptor (IGF-IR) antagonist NVP-AEW541 inhibits proliferation of breast cancer cells and synergizes with trastuzumab. PATIENTS AND METHODS Patient samples and breast cancer cell lines were evaluated for IGF-IR expression or activation by western blotting. 1-(4,5-Dimethylthiazol-2-yl)-3,5-diphenylformazan (MTT) uptake assays and Annexin V staining were used for the analyses of cell proliferation/apoptosis. Biochemical and genomic studies were carried out to gain insights into the mechanism of action of NVP-AEW541. RESULTS The IGF-IR was expressed above normal levels in a number of breast cancer samples. Activation of this receptor was inhibited by NVP-AEW541 that also decreased cell proliferation and increased apoptosis. NVP-AEW541 decreased the amount of pAkt and increased the level of p27. Combination studies with several drugs used in the breast cancer clinic showed that NVP-AEW541 synergistically increased the action of trastuzumab. CONCLUSIONS Our results show the anti-breast cancer action of NVP-AEW541 and support the clinical development of anti-IGF-IR agents, especially in combination with trastuzumab.
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Affiliation(s)
- A Esparís-Ogando
- Instituto de Biología Molecular y Celular del Cáncer, CSIC-Universidad de Salamanca, Salamanca, Spain
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102
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Fereshteh MP, Tilli MT, Kim SE, Xu J, O'Malley BW, Wellstein A, Furth PA, Riegel AT. The nuclear receptor coactivator amplified in breast cancer-1 is required for Neu (ErbB2/HER2) activation, signaling, and mammary tumorigenesis in mice. Cancer Res 2008; 68:3697-706. [PMID: 18483252 DOI: 10.1158/0008-5472.can-07-6702] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Overexpression of the oncogene amplified in breast cancer 1 (AIB1)/steroid receptor coactivator-3 (SRC-3) induces mammary tumorigenesis in mice. In breast cancer, high levels of AIB1/SRC-3 and the growth factor receptor HER2/neu predict resistance to endocrine therapy and poor outcome. However, a mechanistic relationship between AIB1/SRC-3 and HER2/neu in the development of breast cancer has not been shown. Here, we show that deletion of one allele of SRC-3 significantly delays Neu-induced mammary tumor development in mice. Homozygous deletion of SRC-3 in mice completely prevents Neu-induced tumor formation. By ages 3 to 4 months, Neu/SRC-3(+/-) mice exhibit a noticeable reduction in lateral side-bud formation, accompanied by reduced cellular levels of phosphorylated Neu compared with Neu/SRC-3(wt) mice. In Neu-induced tumors, high levels of SRC-3, phosphorylated Neu, cyclin D1, cyclin E, and proliferating cell nuclear antigen expression are observed, accompanied by activation of the AKT and c-Jun NH(2) kinase (JNK) signaling pathways. In comparison, phosphorylated Neu, cyclin D1, and cyclin E are significantly decreased in Neu/SRC-3(+/-) tumors, proliferation is reduced, and AKT and JNK activation is barely detectable. Our data indicate that AIB1/SRC-3 is required for HER2/neu oncogenic activity and for the phosphorylation and activation of the HER2/neu receptor. We predict that reducing AIB1/SRC-3 levels or activity in the mammary epithelium could potentiate therapies aimed at inhibiting HER2/neu signaling in breast cancer.
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Affiliation(s)
- Mark P Fereshteh
- Departments of Oncology and Pharmacology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, District of Columbia, USA
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103
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Ocaña A, Pandiella A. Identifying breast cancer druggable oncogenic alterations: lessons learned and future targeted options. Clin Cancer Res 2008; 14:961-70. [PMID: 18281527 DOI: 10.1158/1078-0432.ccr-07-1630] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Although the introduction of novel therapies and drug combinations has improved the prognosis of metastatic breast cancer, this disease remains incurable. It is therefore important to develop additional novel therapeutic strategies and agents. Increased understanding of the biology and the molecular alterations present in breast cancer is facilitating the design of targeted therapies directed to oncogenic proteins. Here, we review the signaling pathways and proteins that participate in breast cancer proliferation and survival, with special emphasis in those that are druggable. We will also comment on how the knowledge on the basic pathogenetic processes is translated into drug development strategies that are reaching the breast cancer clinic.
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Affiliation(s)
- Alberto Ocaña
- Complejo Hospitalario Universitario de Albacete, Albacete, Spain.
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104
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Bender LM, Nahta R. Her2 cross talk and therapeutic resistance in breast cancer. FRONT BIOSCI-LANDMRK 2008; 13:3906-12. [PMID: 18508484 DOI: 10.2741/2978] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The HER2 receptor tyrosine kinase is amplified and/or overexpressed in approximately 30 percent of metastatic breast cancers. Interactions and cross signaling from the HER2 receptor to other growth factor receptors may potentially contribute to therapeutic resistance. In this review, we discuss HER2 receptor cross talk with the estrogen receptor and implications toward resistance to endocrine therapies. We also review mechanisms of resistance to the HER2-targeted antibody trastuzumab, including signaling from other members of the HER family, increased signaling through the PI3-kinase pathway, and cross talk from the insulin-like growth factor-I receptor to HER2. Finally, we will provide perspective on how HER2 receptor cross talk may provide critical information for developing novel therapeutic options for HER2-overexpressing breast cancers.
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Affiliation(s)
- Laura M Bender
- Department of Pharmacology, School of Medicine, Winship Cancer Institute, Emory University, Atlanta, GA 30322-1013, USA
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105
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Chu IM, Hengst L, Slingerland JM. The Cdk inhibitor p27 in human cancer: prognostic potential and relevance to anticancer therapy. Nat Rev Cancer 2008; 8:253-67. [PMID: 18354415 DOI: 10.1038/nrc2347] [Citation(s) in RCA: 748] [Impact Index Per Article: 46.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The cyclin-dependent kinase (Cdk) inhibitor p27 (also known as KIP1) regulates cell proliferation, cell motility and apoptosis. Interestingly, the protein can exert both positive and negative functions on these processes. Diverse post-translational modifications determine the physiological role of p27. Phosphorylation regulates p27 binding to and inhibition of cyclin-Cdk complexes, its localization and its ubiquitin-mediated proteolysis. In cancers, p27 is inactivated through impaired synthesis, accelerated degradation and by mislocalization. Moreover, studies in several tumour types indicate that p27 expression levels have both prognostic and therapeutic implications.
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Affiliation(s)
- Isabel M Chu
- Braman Family Breast Cancer Institute, and Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, 1580 NW 10th Avenue, Miami, Florida 33136, USA
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106
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Fuller SJ, Sivarajah K, Sugden PH. ErbB receptors, their ligands, and the consequences of their activation and inhibition in the myocardium. J Mol Cell Cardiol 2008; 44:831-54. [PMID: 18430438 DOI: 10.1016/j.yjmcc.2008.02.278] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2007] [Revised: 02/17/2008] [Accepted: 02/23/2008] [Indexed: 12/12/2022]
Abstract
The epidermal growth factor (EGF) receptor (or ErbB1) and the related ErbB4 are transmembrane receptor protein tyrosine kinases which bind extracellular ligands of the EGF family. ErbB2 and ErbB3 are "co-receptors" structurally related to ErbB1/ErbB4, but ErbB2 is an "orphan" receptor and ErbB3 lacks tyrosine kinase activity. However, both are important in transmembrane signalling. All ErbB receptors/ligands are intimately involved in the regulation of cell growth, differentiation and survival, and their dysregulation contributes to some human malignancies. After extracellular ligand binding, receptor dimerisation and transautophosphorylation of intracellular C-terminal tyrosine residues, they bind signalling proteins which recognise specific tyrosine-phosphorylated motifs. This leads to activation of multiple signalling pathways, notably the extracellular signal-regulated kinase 1/2 (ERK1/2) cascade and the phosphoinositide 3-kinase (PI3K)/protein kinase B [PKB/(Akt)] pathway. In heart, targeted deletion of ErbB2, ErbB3, ErbB4 and some ErbB receptor extracellular ligands leads to embryonic lethality resulting from cardiovascular defects. ErbB receptor ligands improve cardiac myocyte viability and are hypertrophic, partly because of activation of ERK1/2 and/or PI3K/PKB(Akt). Furthermore, ErbB transactivation by Gq protein-coupled receptor (GqPCR) signalling may mediate the hypertrophic effects of GqPCR agonists. The utility of anthracyclines in cancer chemotherapy can be limited by their cardiotoxic side effects and these may be counteracted by ErbB receptor ligands. ErbB2 is the target of anti-cancer monoclonal antibody trastuzumab (Herceptin), and its myocardial downregulation may account for the occasional cardiotoxicity of this therapy. Here, we review the basic biochemistry of ErbB receptors/ligands, and emphasise their particular roles in the myocardium.
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Affiliation(s)
- Stephen J Fuller
- NHLI Division, Faculty of Medicine, Imperial College London, Flowers Building, Armstrong Road, London SW7 2AZ, UK
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107
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Le XF, Arachchige-Don AS, Mao W, Horne MC, Bast RC. Roles of human epidermal growth factor receptor 2, c-jun NH2-terminal kinase, phosphoinositide 3-kinase, and p70 S6 kinase pathways in regulation of cyclin G2 expression in human breast cancer cells. Mol Cancer Ther 2008; 6:2843-57. [PMID: 18025271 DOI: 10.1158/1535-7163.mct-07-0109] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The CCNG2 gene that encodes the unconventional cyclin G2 was one of the few genes up-regulated on anti-human epidermal growth factor receptor 2 (HER2) antibody-mediated inhibition of HER2 signaling. The purpose of this study was to explore how HER2 signaling modulates cyclin G2 expression and the effect of elevated cyclin G2 on breast cancer cell growth. Treatment of breast cancer cells that overexpress HER2 (BT474, SKBr3, and MDAMB453) with the anti-HER2 antibody trastuzumab or its precursor 4D5 markedly up-regulated cyclin G2 mRNA in vitro and in vivo, as shown by real-time PCR. Immunoblot and immunofluorescence analysis with specific antibodies against cyclin G2 showed that anti-HER2 antibody significantly increased cyclin G2 protein expression and translocated the protein to the nucleus. Trastuzumab was not able to induce cyclin G2 expression in cells weakly expressing HER2 (MCF7) or in cells that had developed resistance to trastuzumab. Enforced expression of HER2 in T47D and MDAMB435 breast cancer cells reduced cyclin G2 levels. Collectively, these data suggest that HER2-mediated signaling negatively regulates cyclin G2 expression. Inhibition of phosphoinositide 3-kinase (LY294002), c-jun NH(2)-terminal kinase (SP600125), and mammalian target of rapamycin (mTOR)/p70 S6 kinase (p70S6K; rapamycin) increased cyclin G2 expression. In contrast, treatment with inhibitors of p38 mitogen-activated protein kinase (SB203580), mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1/2 (U0126), or phospholipase Cgamma (U73122) did not affect cyclin G2 expression. Anti-HER2 antibody in combination with LY294002, rapamycin, or SP600125 induced greater cyclin G2 expression than either agent alone. Ectopic expression of cyclin G2 inhibited cyclin-dependent kinase 2 activity, Rb phosphorylation, cell cycle progression, and cellular proliferation without affecting p27(Kip1) expression. Thus, cyclin G2 expression is modulated by HER2 signaling through multiple pathways including phosphoinositide 3-kinase, c-jun NH(2)-terminal kinase, and mTOR signaling. The negative effects of cyclin G2 on cell cycle and cell proliferation, which occur without altering p27(Kip1) levels, may contribute to the ability of trastuzumab to inhibit breast cancer cell growth.
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Affiliation(s)
- Xiao-Feng Le
- Department of Experimental Therapeutics, The University of Texas M. D. Anderson Cancer Center, Houston, Texas, USA
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108
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Additive effects of a prolactin receptor antagonist, G129R, and herceptin on inhibition of HER2-overexpressing breast cancer cells. Breast Cancer Res Treat 2007; 111:241-50. [DOI: 10.1007/s10549-007-9789-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2007] [Accepted: 10/08/2007] [Indexed: 10/22/2022]
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109
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Moasser MM. Targeting the function of the HER2 oncogene in human cancer therapeutics. Oncogene 2007; 26:6577-92. [PMID: 17486079 PMCID: PMC3071580 DOI: 10.1038/sj.onc.1210478] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2007] [Accepted: 03/22/2007] [Indexed: 01/15/2023]
Abstract
The year 2007 marks exactly two decades since human epidermal growth factor receptor-2 (HER2) was functionally implicated in the pathogenesis of human breast cancer (Slamon et al., 1987). This finding established the HER2 oncogene hypothesis for the development of some human cancers. An abundance of experimental evidence compiled over the past two decades now solidly supports the HER2 oncogene hypothesis. A direct consequence of this hypothesis was the promise that inhibitors of oncogenic HER2 would be highly effective treatments for HER2-driven cancers. This treatment hypothesis has led to the development and widespread use of anti-HER2 antibodies (trastuzumab) in clinical management resulting in significantly improved clinical antitumor efficacies that have transformed the clinical practice of oncology. In the shadows of this irrefutable clinical success, scientific studies have not yet been able to mechanistically validate that trastuzumab inhibits oncogenic HER2 function and it remains possible that the current clinical advances are a consequence of the oncogene hypothesis, but not a translation of it. These looming scientific uncertainties suggest that the full promise of the treatment hypothesis may not yet have been realized. The coming decade will see a second generation of HER2-targeting agents brought into clinical testing and a renewed attempt to treat HER2-driven cancers through the inactivation of HER2. Here, I review the development of treatments that target HER2 in the context of the HER2 oncogene hypothesis, and where we stand with regards to the clinical translation of the HER2 oncogene hypothesis.
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Affiliation(s)
- M M Moasser
- Department of Medicine, Comprehensive Cancer Center, University of California, San Francisco, CA 94143-0875, USA.
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110
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Ritter CA, Perez-Torres M, Rinehart C, Guix M, Dugger T, Engelman JA, Arteaga CL. Human breast cancer cells selected for resistance to trastuzumab in vivo overexpress epidermal growth factor receptor and ErbB ligands and remain dependent on the ErbB receptor network. Clin Cancer Res 2007; 13:4909-19. [PMID: 17699871 DOI: 10.1158/1078-0432.ccr-07-0701] [Citation(s) in RCA: 391] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
PURPOSE We have investigated mechanisms of acquired resistance to the HER2 antibody trastuzumab in BT-474 human breast cancer cells. EXPERIMENTAL DESIGN BT-474 xenografts established in athymic nude mice were eliminated by trastuzumab. Continuous cell lines (HR for Herceptin resistant) were generated from tumors that recurred in the presence of continuous antibody therapy. RESULTS The isolated cells behaved resistant to trastuzumab in culture as well as when reinjected into nude mice. They retained HER2 gene amplification and trastuzumab binding and were exquisitely sensitive to peripheral blood mononuclear cells ex vivo in the presence of the antibody. The HR cells exhibited higher levels of phosphorylated epidermal growth factor receptor (EGFR) and EGFR/HER2 heterodimers. Phosphorylation of HER2 in HR cells was inhibited by the EGFR tyrosine kinase inhibitors erlotinib and gefitinib. Gefitinib also inhibited the basal association of p85 with phosphorylated HER3 in HR cells. Both inhibitors as well as the dual EGFR/HER2 inhibitor, lapatinib, induced apoptosis of the HR cells in culture. Growth of established HR5 xenografts was inhibited by erlotinib in vivo. In addition, the HR cells overexpressed EGFR, transforming growth factor alpha, heparin-binding EGF, and heregulin RNAs compared with the parental trastuzumab-sensitive cells. CONCLUSIONS These results are consistent with the inability of trastuzumab to block the heterodimerization of HER2 and suggest that amplification of ligand-induced activation of ErbB receptors is a plausible mechanism of acquired resistance to trastuzumab that should be investigated in primary mammary cancers.
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Affiliation(s)
- Christoph A Ritter
- Institute of Pharmacology, University of Greifswald, Greifswald, Germany
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111
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Spänkuch B, Kurunci-Csacsko E, Kaufmann M, Strebhardt K. Rational combinations of siRNAs targeting Plk1 with breast cancer drugs. Oncogene 2007; 26:5793-807. [PMID: 17369857 DOI: 10.1038/sj.onc.1210355] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Revised: 01/09/2007] [Accepted: 01/24/2007] [Indexed: 12/18/2022]
Abstract
Commonly used drugs for the treatment of breast cancer patients like paclitaxel and Herceptin often show severe side effects or induce resistance in clinical settings. Thus, we analysed a combination of Plk1 (polo-like kinase 1)-specific small interfering RNAs (siRNAs), a powerful tool to induce 'mitotic catastrophe' in cancer cells, together with these drugs to identify conditions for enhanced drug sensitivity. After transfection, the antineoplastic agents were added and cell proliferation, apoptosis and cell cycle distribution in breast cancer cells (MCF-7, SK-BR-3, MDA-MB-435 and BT-474) and in primary human mammary epithelial cells were determined. Downregulation of cellular Plk1 levels led to an elevated percentage of cells in G(2)/M phase. The percentage of apoptotic nuclei in MCF-7, MDA-MB-435, SK-BR-3 and BT-474 cells was clearly increased after incubation with Plk1-specific siRNAs and paclitaxel. Interestingly, the caspase pathway was activated after treatment with Plk1-specific siRNAs and paclitaxel or Herceptin. Treatment of breast cancer cells with siRNAs targeting Plk1 improved the sensitivity toward paclitaxel and Herceptin in a synergistic manner. In all experiments, very low concentrations across a wide range of clinically relevant concentrations were sufficient to induce an antiproliferative effect. The combination of Plk1-specific siRNAs with modern breast cancer drugs seems to represent rational combinations to be tested in preclinical trials.
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MESH Headings
- Antibodies, Monoclonal/therapeutic use
- Antibodies, Monoclonal, Humanized
- Antineoplastic Agents/therapeutic use
- Antineoplastic Agents, Phytogenic/therapeutic use
- Apoptosis/drug effects
- Breast Neoplasms/drug therapy
- Breast Neoplasms/enzymology
- Breast Neoplasms/genetics
- Breast Neoplasms/metabolism
- Breast Neoplasms/pathology
- Breast Neoplasms/therapy
- Cell Cycle/drug effects
- Cell Cycle Proteins/antagonists & inhibitors
- Cell Cycle Proteins/genetics
- Cell Cycle Proteins/metabolism
- Cell Proliferation
- Cyclin-Dependent Kinase Inhibitor p27/metabolism
- Down-Regulation
- Drug Screening Assays, Antitumor
- Drug Therapy, Combination
- Female
- Humans
- Paclitaxel/therapeutic use
- Protein Serine-Threonine Kinases/antagonists & inhibitors
- Protein Serine-Threonine Kinases/genetics
- Protein Serine-Threonine Kinases/metabolism
- Proto-Oncogene Proteins/antagonists & inhibitors
- Proto-Oncogene Proteins/genetics
- Proto-Oncogene Proteins/metabolism
- RNA, Small Interfering/therapeutic use
- Receptor, ErbB-2/immunology
- Receptor, ErbB-2/metabolism
- Transfection
- Trastuzumab
- Tumor Cells, Cultured
- Polo-Like Kinase 1
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Affiliation(s)
- B Spänkuch
- Department of Obstetrics and Gynecology, Medical School, JW Goethe-University, Frankfurt, Germany.
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112
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Affiliation(s)
- Nancy E Hynes
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
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113
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Abstract
ErbB receptors are essential mediators of cell proliferation and differentiation. Their aberrant activation is associated with the development and severity of many cancers. Homo- and heterodimerization of ErbB receptors result in a wide variety of cellular signal transduction. Dimerization of human epidermal growth-factor receptor (HER)2 and HER3 occurs frequently and is a preferred heterodimer. The HER2/HER3 dimer constitutes a high affinity co-receptor for heregulin, which is capable of potent mitogenic signaling. HER3 is a kinase-defective protein that is phosphorylated by HER2. Tyrosine phosphorylated HER3 is able to directly couple to phosphatidylinositide 3-kinase, a lipid kinase involved in the proliferation, survival, adhesion and motility of tumor cells. The authors' research provides mechanistic evidence that apigenin induces apoptosis by depleting the HER2 protein and, in turn, suppressing the signaling of the HER2/HER3-phosphatidylinositide 3-kinase/Akt pathway. This indicates that inhibition of HER2/HER3 heterodimer function may be an especially effective and unique strategy for blocking the HER2-mediated carcinogenesis of breast cancer cells.
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Affiliation(s)
- Tzong-Der Way
- Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, Taiwan
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114
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Abstract
The human epidermal growth factor receptor 2 (HER2) tyrosine kinase receptor is overexpressed in approximately 20-30% of human breast cancers, and is associated with reduced survival. Hence, numerous therapeutic strategies have been tested for their ability to target the HER2 protein. The humanized monoclonal antibody trastuzumab (Herceptin) was the first HER2-targeted agent approved for clinical use in breast cancer patients. Response rates to single-agent trastuzumab range from 12 to 34% for metastatic breast cancer (MBC), and significant improvements in survival rates are achieved in patients with early-stage HER2-overexpressing breast cancer in the adjuvant setting. Despite its initial efficacy, acquired resistance to trastuzumab develops in a majority of patients with MBC, and a large subset never responds, demonstrating primary resistance. Molecular mechanisms of trastuzumab antineoplastic activity and potential mechanisms contributing to its resistance will be discussed in this review. Novel agents that may enhance trastuzumab efficacy will also be discussed.
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Affiliation(s)
- R Nahta
- Department of Breast Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030-4009, USA.
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115
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Porter PL, Barlow WE, Yeh IT, Lin MG, Yuan X, Donato E, Sledge GW, Shapiro CL, Ingle JN, Haskell CM, Albain KS, Roberts JM, Livingston RB, Hayes DF. Re: p27(Kip1) and cyclin E expression and breast cancer survival after treatment with adjuvant chemotherapy. J Natl Cancer Inst 2007; 99:738. [PMID: 17470742 PMCID: PMC7717107 DOI: 10.1093/jnci/djk163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- PL Porter
- Fred Hutchinson Cancer Research Center, Seattle WA
- University of Washington, Seattle WA
- Address for editorial correspondence: Peggy L. Porter, M.D., Member, Human Biology and Public Health Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N, Seattle, WA 98109, PH: 206-667-3751; FAX: 206-667-5815,
| | - WE Barlow
- University of Washington, Seattle WA
- SWOG Statistical Center, Seattle WA
| | - I-T Yeh
- University of Texas Health Science Center, San Antonio, TX
| | - M-G Lin
- Fred Hutchinson Cancer Research Center, Seattle WA
| | - X Yuan
- Fred Hutchinson Cancer Research Center, Seattle WA
| | - E Donato
- Fred Hutchinson Cancer Research Center, Seattle WA
| | - GW Sledge
- Indiana University, Indianapolis, IN
| | | | | | - CM Haskell
- University of California, Los Angeles CA
| | | | - JM Roberts
- Fred Hutchinson Cancer Research Center, Seattle WA
| | | | - DF Hayes
- University of Michigan, Ann Arbor MI
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116
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Koziczak-Holbro M, Joyce C, Glück A, Kinzel B, Müller M, Tschopp C, Mathison JC, Davis CN, Gram H. IRAK-4 kinase activity is required for interleukin-1 (IL-1) receptor- and toll-like receptor 7-mediated signaling and gene expression. J Biol Chem 2007; 282:13552-60. [PMID: 17337443 DOI: 10.1074/jbc.m700548200] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
IRAK-4 is an essential component of the signal transduction complex downstream of the IL-1- and Toll-like receptors. Although regarded as the first kinase in the signaling cascade, the role of IRAK-4 kinase activity versus its scaffold function is still controversial. To investigate the role of IRAK-4 kinase function in vivo, "knock-in" mice were generated by replacing the wild type IRAK-4 gene with a mutant gene encoding kinase-deficient IRAK-4 protein (IRAK-4 KD). IRAK-4 kinase was rendered inactive by mutating the conserved lysine residues in the ATP pocket essential for coordinating ATP. Analyses of embryonic fibroblasts and macrophages obtained from IRAK-4 KD mice demonstrate lack of cellular responsiveness to stimulation with IL-1beta or a Toll-like receptor 7 (TLR7) agonist. IRAK-4 kinase deficiency prevents the recruitment of IRAK-1 to the IL-1 receptor complex and its subsequent phosphorylation and degradation. IRAK-4 KD cells are severely impaired in NFkappaB, JNK, and p38 activation in response to IL-1beta or TLR7 ligand. As a consequence, IL-1 receptor/TLR7-mediated production of cytokines and chemokines is largely absent in these cells. Additionally, microarray analysis identified IL-1beta response genes and revealed that the induction of IL-1beta-responsive mRNAs is largely ablated in IRAK-4 KD cells. In summary, our results suggest that IRAK-4 kinase activity plays a critical role in IL-1 receptor (IL-1R)/TLR7-mediated induction of inflammatory responses.
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MESH Headings
- Animals
- Cell Line
- Embryo, Mammalian/cytology
- Embryo, Mammalian/metabolism
- Fibroblasts/cytology
- Fibroblasts/metabolism
- Inflammation/genetics
- Inflammation/metabolism
- Interleukin-1 Receptor-Associated Kinases/deficiency
- Interleukin-1 Receptor-Associated Kinases/metabolism
- Macrophages/cytology
- Macrophages/metabolism
- Membrane Glycoproteins/agonists
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/metabolism
- Mice
- Mice, Inbred BALB C
- Mice, Knockout
- Multiprotein Complexes/genetics
- Multiprotein Complexes/metabolism
- Mutation
- Phosphorylation
- Protein Processing, Post-Translational/physiology
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- Receptors, Interleukin-1/agonists
- Receptors, Interleukin-1/genetics
- Receptors, Interleukin-1/metabolism
- Signal Transduction/physiology
- Toll-Like Receptor 7/agonists
- Toll-Like Receptor 7/genetics
- Toll-Like Receptor 7/metabolism
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117
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Furuuchi K, Berezov A, Kumagai T, Greene MI. Targeted antireceptor therapy with monoclonal antibodies leads to the formation of inactivated tetrameric forms of ErbB receptors. THE JOURNAL OF IMMUNOLOGY 2007; 178:1021-9. [PMID: 17202365 DOI: 10.4049/jimmunol.178.2.1021] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
mAbs capable of disabling heterodimeric kinase complexes of the epidermal growth factor receptor (EGFR) and human EGFR type 2/neu have therapeutic relevance to various human cancers. In this study, we demonstrate that in addition to the dimer, EGFR and human EGFR type 2 can associate as homo- and heterotetramers. EGF-induced phosphorylation of the tetramers was significantly lower than that of the dimers, indicating that the tetrameric receptor complexes have impaired signaling activity. Targeting v-erb-b2 erythroblastic leukemia viral oncogene homolog (erbB) receptors with mAbs promoted erbB tetrameric assembly, suggesting that a component of the antitumor activity may be mediated by the ability of Abs to shift the equilibrium from active dimeric to impaired tetrameric receptor complex states. This study suggests a novel therapeutic approach to disable signaling of erbB and potentially other receptors in tumors by biologic agents capable of inducing receptor tetramerization.
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Affiliation(s)
- Keiji Furuuchi
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine and Abramson Family Cancer Research Institute, 36th Hamilton Walk, Philadelphia, PA 19104, USA
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118
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Yasmeen A, Bismar TA, Al Moustafa AE. ErbB receptors and epithelial-cadherin-catenin complex in human carcinomas. Future Oncol 2007; 2:765-81. [PMID: 17155902 DOI: 10.2217/14796694.2.6.765] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The ErbB family of receptor tyrosine kinases have important roles in maintaining normal epithelial cell function. The ErbBs are involved in the interaction between cells and cell-matrix adhesion molecules and have proven critical in maintaining the integrity of the epithelial cell environment. Deregulation of these tyrosine receptors has been associated with several human diseases. In particular, the expression or activation of epidermal growth factor receptor (EGFR) and ErbB2 is altered in many epithelial tumors. Epithelial (E)-cadherin is another major molecule expressed by epithelial cells. To create efficient cell-cell adhesion, E-cadherin couples its cytoplasmic domain to catenins and the actin cytoskeleton. The loss of intercellular adhesion appears to be a fundamental aspect of the neoplastic phenomena. In addition, EGFR and ErbB2 signaling associated with the E-cadherin-catenin complex has been demonstrated in normal and cancer cells. This signaling is involved in regulating cell adhesion and the invasive growth of cancers. This article provides an overview of the interaction between the ErbB tyrosine receptors and the E-cadherin-catenin complex in human carcinomas.
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Affiliation(s)
- Amber Yasmeen
- McGill University, Program in Cancer Genetics, Department of Oncology, Montreal, Quebec, Canada.
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119
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Julien SG, Dubé N, Read M, Penney J, Paquet M, Han Y, Kennedy BP, Muller WJ, Tremblay ML. Protein tyrosine phosphatase 1B deficiency or inhibition delays ErbB2-induced mammary tumorigenesis and protects from lung metastasis. Nat Genet 2007; 39:338-46. [PMID: 17259984 DOI: 10.1038/ng1963] [Citation(s) in RCA: 251] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2006] [Accepted: 12/18/2006] [Indexed: 11/08/2022]
Abstract
We investigated the role of protein tyrosine phosphatase 1B (PTP1B) in mammary tumorigenesis using both genetic and pharmacological approaches. It has been previously shown that transgenic mice with a deletion mutation in the region of Erbb2 encoding its extracellular domain (referred to as NDL2 mice, for 'Neu deletion in extracellular domain 2') develop mammary tumors that progress to lung metastasis. However, deletion of PTP1B activity in the NDL2 transgenic mice either by breeding with Ptpn1-deficient mice or by treatment with a specific PTP1B inhibitor results in significant mammary tumor latency and resistance to lung metastasis. In contrast, specific overexpression of PTP1B in the mammary gland leads to spontaneous breast cancer development. The regulation of ErbB2-induced mammary tumorigenesis by PTB1B occurs through the attenuation of both the MAP kinase (MAPK) and Akt pathways. This report provides a rationale for the development of PTP1B as a new therapeutic target in breast cancer.
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MESH Headings
- Animals
- Apoptosis
- Cell Line, Tumor
- Down-Regulation
- Female
- Lung/metabolism
- Lung Neoplasms/metabolism
- Lung Neoplasms/prevention & control
- Lung Neoplasms/secondary
- MAP Kinase Signaling System/physiology
- Mammary Glands, Animal/drug effects
- Mammary Neoplasms, Experimental/enzymology
- Mammary Neoplasms, Experimental/etiology
- Mammary Neoplasms, Experimental/pathology
- Mice
- Mice, Knockout
- Mice, Transgenic
- Molecular Sequence Data
- Phenotype
- Protein Tyrosine Phosphatase, Non-Receptor Type 1
- Protein Tyrosine Phosphatases/antagonists & inhibitors
- Protein Tyrosine Phosphatases/genetics
- Protein Tyrosine Phosphatases/physiology
- Proto-Oncogene Proteins c-akt/metabolism
- Receptor, ErbB-2/metabolism
- Receptor, ErbB-3/metabolism
- Signal Transduction
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Affiliation(s)
- Sofi G Julien
- McGill Cancer Centre, McGill University, 3655 Sir William Osler Promenade, Montreal, Quebec H3G 1Y6, Canada
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Kim WE, Serrero G. PC cell-derived growth factor stimulates proliferation and confers Trastuzumab resistance to Her-2-overexpressing breast cancer cells. Clin Cancer Res 2007; 12:4192-9. [PMID: 16857791 DOI: 10.1158/1078-0432.ccr-05-2663] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Trastuzumab is only effective in 25% to 30% of the administered breast cancer patients who overexpress the erbB2/Her-2 oncoprotein. PC cell-derived growth factor (PCDGF/GP88) is an 88-kDa glycoprotein growth factor overexpressed in 80% invasive ductal carcinomas. Our objective was to determine whether the increased levels of PCDGF/GP88 confers Trastuzumab resistance in erbB2-overexpressing breast cancer cells. EXPERIMENTAL DESIGN The ability of PCDGF to induce erbB2 phosphorylation and to confer Trastuzumab resistance was studied in erbB2-overexpressing MCF-7 and SKBR3 breast cancer cell lines. RESULTS PCDGF/GP88 added exogenously induced the phosphorylation of erbB2 in a dose-dependent and time-dependent manner in erbB2-overexpressing breast cancer cells. In addition, the overexpression of PCDGF/GP88 conferred Trastuzumab resistance in erbB2-overexpressing cells. Furthermore, overexpression of PCDGF/GP88 in erbB2-overexpressing cells provided a growth advantage over erbB2-overexpressing cells that do not have increased levels of PCDGF/GP88. Lastly, PCDGF/GP88 induced the phosphorylation of mitogen-activated protein kinase in a time-dependent manner in erbB2-overexpressing cells, and pretreatment with Trastuzumab was not able to attenuate the phosphorylation levels of mitogen-activated protein kinase induced by PCDGF/GP88. CONCLUSION These data suggest that PCDGF/GP88 confers Trastuzumab resistance in erbB2-overexpressing cells. Thus, the increase in PCDGF/GP88 levels may indicate Trastuzumab unresponsiveness in breast cancer patients.
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Affiliation(s)
- Wes E Kim
- A&G Pharmaceutical, Inc., Columbia, Maryland 21045, USA
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121
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Chu I, Sun J, Arnaout A, Kahn H, Hanna W, Narod S, Sun P, Tan CK, Hengst L, Slingerland J. p27 phosphorylation by Src regulates inhibition of cyclin E-Cdk2. Cell 2007; 128:281-94. [PMID: 17254967 PMCID: PMC1961623 DOI: 10.1016/j.cell.2006.11.049] [Citation(s) in RCA: 284] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2006] [Revised: 10/03/2006] [Accepted: 11/20/2006] [Indexed: 01/02/2023]
Abstract
The kinase inhibitor p27Kip1 regulates the G1 cell cycle phase. Here, we present data indicating that the oncogenic kinase Src regulates p27 stability through phosphorylation of p27 at tyrosine 74 and tyrosine 88. Src inhibitors increase cellular p27 stability, and Src overexpression accelerates p27 proteolysis. Src-phosphorylated p27 is shown to inhibit cyclin E-Cdk2 poorly in vitro, and Src transfection reduces p27-cyclin E-Cdk2 complexes. Our data indicate that phosphorylation by Src impairs the Cdk2 inhibitory action of p27 and reduces its steady-state binding to cyclin E-Cdk2 to facilitate cyclin E-Cdk2-dependent p27 proteolysis. Furthermore, we find that Src-activated breast cancer lines show reduced p27 and observe a correlation between Src activation and reduced nuclear p27 in 482 primary human breast cancers. Importantly, we report that in tamoxifen-resistant breast cancer cell lines, Src inhibition can increase p27 levels and restore tamoxifen sensitivity. These data provide a new rationale for Src inhibitors in cancer therapy.
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Affiliation(s)
- Isabel Chu
- Braman Family Breast Cancer Institute, and Department of Biochemistry and Molecular Biology, U. of Miami Miller School of Medicine, Miami, Florida; U.S.A
- Departments of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Jun Sun
- Braman Family Breast Cancer Institute, and Department of Biochemistry and Molecular Biology, U. of Miami Miller School of Medicine, Miami, Florida; U.S.A
| | - Angel Arnaout
- Surgery, University of Toronto, Toronto, Ontario, Canada
| | - Harriette Kahn
- Pathobiology and Lab Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Wedad Hanna
- Pathobiology and Lab Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Steven Narod
- Pathobiology and Lab Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Ping Sun
- Pathobiology and Lab Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Cheng-Keat Tan
- Braman Family Breast Cancer Institute, and Department of Biochemistry and Molecular Biology, U. of Miami Miller School of Medicine, Miami, Florida; U.S.A
| | - Ludger Hengst
- Division of Medical Biochemistry, Biocenter - Innsbruck Medical University, Innsbruck, Austria
| | - Joyce Slingerland
- Braman Family Breast Cancer Institute, and Department of Biochemistry and Molecular Biology, U. of Miami Miller School of Medicine, Miami, Florida; U.S.A
- Departments of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
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Porter PL, Barlow WE, Yeh IT, Lin MG, Yuan XP, Donato E, Sledge GW, Shapiro CL, Ingle JN, Haskell CM, Albain KS, Roberts JM, Livingston RB, Hayes DF. p27(Kip1) and cyclin E expression and breast cancer survival after treatment with adjuvant chemotherapy. J Natl Cancer Inst 2007; 98:1723-31. [PMID: 17148774 PMCID: PMC2727647 DOI: 10.1093/jnci/djj467] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Abnormal expression of the cell cycle regulatory proteins p27(Kip1) (p27) and cyclin E may be associated with breast cancer survival and relapse. We studied these markers in a clinical trial setting with patients with breast cancer treated by a uniform drug regimen so that treatment was not associated with variability in outcome. METHODS We used tissue microarrays to evaluate the expression of p27 and cyclin E proteins by immunohistochemistry in tumor tissue from 2123 (68%) of 3122 patients with moderate-risk primary breast cancer who were enrolled in Southwest Oncology Group-Intergroup Trial S9313, in which patients were assigned to receive doxorubicin and cyclophosphamide administered concurrently (n = 1595) or sequentially (n = 1527). Disease-free and overall survival were equivalent in the two arms. Expression of the proteins was rated on a scale of 1-7, and the median value was used as the cut point. Log-rank tests and Cox regression analyses were used to assess associations with survival. Overall survival was defined as time to death from all causes; disease-free survival was defined as time to recurrence or death. All P values were from two-sided statistical tests. RESULTS Lower p27 expression was associated with worse overall survival (unadjusted hazard ratio [HR] = 1.50, 95% confidence interval [CI] = 1.21 to 1.86) and disease-free survival (unadjusted HR = 1.31, 95% CI = 1.10 to 1.57) than higher p27 expression. Among hormone receptor-positive patients, lower p27 expression was associated with worse overall survival (HR = 1.42, 95% CI = 1.05 to 1.94) and worse disease-free survival (HR = 1.27, 95% CI = 0.99 to 1.63) than higher p27 expression after adjustment for treatment, menopausal status, tumor size, and number of positive lymph nodes. Among these patients, 5-year overall survival associated with higher p27 expression (0.91, 95% CI = 0.89 to 0.93) was similar to that associated with lower p27 expression (0.85, 95% CI = 0.82 to 0.87). No association between p27 expression and survival was found in hormone receptor-negative patients. Cyclin E expression was not statistically significantly associated with overall survival (HR = 1.12, 95% CI = 0.91 to 1.38) or disease-free survival (HR = 1.09, 95% CI = 0.92 to 1.29). CONCLUSIONS Low p27 expression appears to be associated with poor prognosis, especially among patients with steroid receptor-positive tumors.
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Affiliation(s)
- Peggy L Porter
- Division of Human Biology and Public Health Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N, Seattle, WA 98109, USA.
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124
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Bernard-Marty C, Lebrun F, Awada A, Piccart MJ. Monoclonal antibody-based targeted therapy in breast cancer: current status and future directions. Drugs 2006; 66:1577-91. [PMID: 16956305 DOI: 10.2165/00003495-200666120-00004] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The recent development of monoclonal antibodies targeting growth factor receptors in cancer treatment represents a milestone for both researchers and physicians. Advances in the understanding of key molecular pathways for tumour growth and survival have facilitated the development of these targeted therapies, in particular in breast cancer. This review focuses on the three most important recombinant humanised monoclonal antibodies that have shown activity in women with breast cancer: trastuzumab, pertuzumab and bevacizumab. Trastuzumab, an anti-erbB2 (human epidermal growth factor receptor) monoclonal antibody, is currently routinely used in both the metastatic and adjuvant settings for patients with erbB2-positive tumours. Pertuzumab, a monoclonal antibody binding to a different epitope on erbB2 than trastuzumab, is under early clinical evaluation. This drug has been developed for breast cancer patients, whether overexpressing erbB2 or not. Bevacizumab, a monoclonal antibody directed against vascular endothelial growth factor-A, is being evaluated in the metastatic setting for its antiangiogenic properties, and is showing promising results.
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125
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Cardoso F, Durbecq V, Laes JF, Badran B, Lagneaux L, Bex F, Desmedt C, Willard-Gallo K, Ross JS, Burny A, Piccart M, Sotiriou C. Bortezomib (PS-341, Velcade) increases the efficacy of trastuzumab (Herceptin) in HER-2-positive breast cancer cells in a synergistic manner. Mol Cancer Ther 2006; 5:3042-51. [PMID: 17148762 DOI: 10.1158/1535-7163.mct-06-0104] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Preclinical and clinical studies have shown that the proteasome inhibitor bortezomib (PS341, Velcade) is highly effective when combined with chemotherapeutic agents. The value of trastuzumab (Herceptin) in HER-2-positive (3+ score by immunohistochemistry or fluorescence in situ hybridization positive) breast cancer is also known; however, the response rate is <40% for metastatic breast cancer. These two pharmacologic agents prevent nuclear factor-kappaB (NF-kappaB) activation and induce nuclear accumulation of the cyclin-dependent kinase inhibitor p27(kip1), suggesting that combining bortezomib with trastuzumab could increase trastuzumab efficacy. METHODS Drug cytotoxicity, both individually and together, and drug effects on p27 localization and NF-kappaB activation were investigated on four breast cancer cell lines: SKBR-3 (HER-2+++), MDA-MB-453 (HER-2++), HER-2-transfected MCF-7 (HER-2+++), and MCF-7 (HER-2-). RESULTS Bortezomib induced apoptosis in HER-2-positive and HER-2-negative breast cancer cells in a dose- and time-dependent manner. Together, these drugs induced apoptosis of HER-2++/+++ cells at low concentrations, which had no effect when used alone, indicating there was a synergistic effect. Sequential treatment (trastuzumab then bortezomib) induced either necrosis or apoptosis, depending on the trastuzumab preincubation time. Susceptibility to bortezomib alone and the drug combination correlated with NF-kappaB activity and p27 localization. CONCLUSIONS The addition of bortezomib to trastuzumab increases the effect of trastuzumab in HER-2+++/++ cell lines in a synergistic way. This effect likely results from the ability of these two drugs to target the NF-kappaB and p27 pathways. The potential clinical application of this drug combination is under current evaluation by our group in a phase 1 clinical trial.
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Affiliation(s)
- Fatima Cardoso
- Translational Research Unit, Center for Education and Research in Food and Chemical Industry, Université libre de Bruxelles, Belgium.
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Neve RM, Chin K, Fridlyand J, Yeh J, Baehner FL, Fevr T, Clark L, Bayani N, Coppe JP, Tong F, Speed T, Spellman PT, DeVries S, Lapuk A, Wang NJ, Kuo WL, Stilwell JL, Pinkel D, Albertson DG, Waldman FM, McCormick F, Dickson RB, Johnson MD, Lippman M, Ethier S, Gazdar A, Gray JW. A collection of breast cancer cell lines for the study of functionally distinct cancer subtypes. Cancer Cell 2006; 10:515-27. [PMID: 17157791 PMCID: PMC2730521 DOI: 10.1016/j.ccr.2006.10.008] [Citation(s) in RCA: 2391] [Impact Index Per Article: 132.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2006] [Revised: 09/05/2006] [Accepted: 10/17/2006] [Indexed: 01/18/2023]
Abstract
Recent studies suggest that thousands of genes may contribute to breast cancer pathophysiologies when deregulated by genomic or epigenomic events. Here, we describe a model "system" to appraise the functional contributions of these genes to breast cancer subsets. In general, the recurrent genomic and transcriptional characteristics of 51 breast cancer cell lines mirror those of 145 primary breast tumors, although some significant differences are documented. The cell lines that comprise the system also exhibit the substantial genomic, transcriptional, and biological heterogeneity found in primary tumors. We show, using Trastuzumab (Herceptin) monotherapy as an example, that the system can be used to identify molecular features that predict or indicate response to targeted therapies or other physiological perturbations.
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Affiliation(s)
- Richard M Neve
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94270, USA.
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127
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Mukherji M, Brill LM, Ficarro SB, Hampton GM, Schultz PG. A Phosphoproteomic Analysis of the ErbB2 Receptor Tyrosine Kinase Signaling Pathways†. Biochemistry 2006; 45:15529-40. [PMID: 17176074 DOI: 10.1021/bi060971c] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Overexpression of the ErbB2 receptor tyrosine kinase is common in human cancers and is associated with an increased level of metastasis. To better understand the cellular signaling networks activated by ErbB2, a phosphoproteomic analysis of tyrosine-phosphorylated proteins was carried out in ErbB2-overexpressing breast and ovarian cancer cell lines. A total of 153 phosphorylation sites were assigned on 78 proteins. Treatment of cells with Herceptin, a monoclonal antibody that inhibits ErbB2 activity, significantly reduced the number of detectable protein phosphorylation sites, suggesting that many of these proteins participate in ErbB2-driven cell signaling. Of the 71 proteins that were differentially phosphorylated, only 13 were previously reported to directly associate with ErbB2. The differentially phosphorylated proteins included kinases, adaptor/docking proteins, proteins involved in cell proliferation and migration, and several uncharacterized RNA binding proteins. Selective depletion of some of these proteins, including RNA binding proteins SRRM2, SFRS1, SFRS9, and SFRS10, by siRNAs reduced the rate of migration of ErbB2-overexpressing ovarian cancer cells.
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Affiliation(s)
- Mridul Mukherji
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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Montero JC, Rodríguez-Barrueco R, Yuste L, Juanes PP, Borges J, Esparís-Ogando A, Pandiella A. The extracellular linker of pro-neuregulin-alpha2c is required for efficient sorting and juxtacrine function. Mol Biol Cell 2006; 18:380-93. [PMID: 17108327 PMCID: PMC1783780 DOI: 10.1091/mbc.e06-06-0511] [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: 11/11/2022] Open
Abstract
The neuregulins (NRGs) play important roles in animal physiology, and their disregulation has been linked to diseases such as cancer or schizophrenia. The NRGs may be produced as transmembrane proteins (proNRGs), even though they lack an N-terminal signal sequence. This raises the question of how NRGs are sorted to the plasma membrane. It is also unclear whether in their transmembrane state, the NRGs are biologically active. During studies aimed at solving these questions, we found that deletion of the extracellular juxtamembrane region termed the linker, decreased cell surface exposure of the mutant proNRG(DeltaLinker), and caused its entrapment at the cis-Golgi. We also found that cell surface-exposed transmembrane NRG forms retain biological activity. Thus, a mutant whose cleavage is impaired but is correctly sorted to the plasma membrane activated ErbB receptors in trans and also stimulated proliferation. Because the linker is implicated in surface sorting and the regulation of the cleavage of transmembrane NRGs, our data indicate that this region exerts multiple important roles in the physiology of NRGs.
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Affiliation(s)
- Juan C. Montero
- Instituto de Biología Molecular y Celular del Cáncer, Centro de Investigación del Cáncer, Consejo Superior de Investigaciones Científicas-Universidad de Salamanca, 37007 Salamanca, Spain
| | - Ruth Rodríguez-Barrueco
- Instituto de Biología Molecular y Celular del Cáncer, Centro de Investigación del Cáncer, Consejo Superior de Investigaciones Científicas-Universidad de Salamanca, 37007 Salamanca, Spain
| | - Laura Yuste
- Instituto de Biología Molecular y Celular del Cáncer, Centro de Investigación del Cáncer, Consejo Superior de Investigaciones Científicas-Universidad de Salamanca, 37007 Salamanca, Spain
| | - Pedro P. Juanes
- Instituto de Biología Molecular y Celular del Cáncer, Centro de Investigación del Cáncer, Consejo Superior de Investigaciones Científicas-Universidad de Salamanca, 37007 Salamanca, Spain
| | - Joana Borges
- Instituto de Biología Molecular y Celular del Cáncer, Centro de Investigación del Cáncer, Consejo Superior de Investigaciones Científicas-Universidad de Salamanca, 37007 Salamanca, Spain
| | - Azucena Esparís-Ogando
- Instituto de Biología Molecular y Celular del Cáncer, Centro de Investigación del Cáncer, Consejo Superior de Investigaciones Científicas-Universidad de Salamanca, 37007 Salamanca, Spain
| | - Atanasio Pandiella
- Instituto de Biología Molecular y Celular del Cáncer, Centro de Investigación del Cáncer, Consejo Superior de Investigaciones Científicas-Universidad de Salamanca, 37007 Salamanca, Spain
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Mehra R, Burtness B. Antibody therapy for early-stage breast cancer: trastuzumab adjuvant and neoadjuvant trials. Expert Opin Biol Ther 2006; 6:951-62. [PMID: 16918262 DOI: 10.1517/14712598.6.9.951] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The HER2/neu gene is amplified in approximately 25% of breast cancers; amplification is associated with an aggressive course. Her2/neu activation initiates signalling cascades that result in proliferation, angiogenesis and survival of breast cancer cells. Trastuzumab is a monoclonal antibody against Her2. Binding of the antibody activates an immune response and decreases Her2 phosphorylation, phosphatidylinositol 3-kinase (PI3K)/Akt activity and vascular endothelial growth factor levels. When trastuzumab is used preoperatively, apoptosis is seen in resected tumours. In the adjuvant setting, large, randomised trials demonstrate improved outcome for trastuzumab with chemotherapy followed by a year of trastuzumab. In a combined analysis of two such studies, overall survival was improved (hazard ratio for death 0.67, p = 0.015). The agent has associated cardiotoxicity. Trastuzumab is a highly active agent in Her2-overexpressing breast cancer.
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Affiliation(s)
- Ranee Mehra
- Fox Chase Cancer Center, Division of Medical Sciences, Department of Medical Oncology, 333 Cottman Ave, Philadelphia, PA 19111, USA
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Menendez JA, Mehmi I, Lupu R. Trastuzumab in Combination With Heregulin-Activated Her-2 (erbB-2) Triggers a Receptor-Enhanced Chemosensitivity Effect in the Absence of Her-2 Overexpression. J Clin Oncol 2006; 24:3735-46. [PMID: 16847284 DOI: 10.1200/jco.2005.04.3489] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Purpose The decision for treating breast cancer patients with trastuzumab is based on HER-2 amplification and/or overexpression. Methods Using MCF-7 cells (Her-2 ±) engineered to overexpress heregulin (MCF-7/HRG), a ligand for the Her-2/3/4 network, we investigated whether HRG-induced transactivation of Her-2 affected breast cancer cell sensitivity to chemotherapy and whether trastuzumab trigger receptor-enhanced chemosensitivity (REC) when combined with chemotherapy without Her-2 overexpression. Results MCF-7/HRG cells were more than 10-fold resistant to the alkylating agent cisplatin (CDDP), while trastuzumab coexposure completely reversed HRG-promoted CDDP resistance. A synergistic interaction between trastuzumab in combination with CDDP (paclitaxel or vincristine) was obtained in MCF-7/HRG cells. Trastuzumab prevented activation of the antiapoptotic and proliferative cascades and inhibited HRG-induced Her-2/3 phosphorylation. CDDP efficacy was enhanced by trastuzumab in cells expressing endogenously high levels of HRG. Conversely, trastuzumab coexposure was ineffective in enhancing chemotherapy efficacy in cells that did not secrete HRG, such as MCF-7 cells overexpressing a structural mutated HRG isoform. Therefore, trastuzumab-induced REC, in the absence of Her-2 overexpression, occurs through the kinase activity of Her-2/3. Interestingly, HRG expression in tumor biopsies from invasive breast carcinomas (n = 189) revealed that, whereas the minority (12%) of Her-2 positive tumors (n = 60; 32%) demonstrated Her-2 phosphorylation, the majority (67%) of HRG-overexpressing and Her-2 tumors (n = 57; 30%) were in active Her-2 status. Conclusion We demonstrate that assessment of HRG expression and Her-2 activation define a particular breast cancer patient population for which trastuzumab plus CDDP or taxol are extremely efficient without Her-2 overexpression.
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Affiliation(s)
- Javier A Menendez
- Department of Medicine, Evanston Northwestern Healthcare Research Institute, Evanston, IL 60201, USA
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131
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Arteaga CL. Can trastuzumab be effective against tumors with low HER2/Neu (ErbB2) receptors? J Clin Oncol 2006; 24:3722-5. [PMID: 16847283 DOI: 10.1200/jco.2006.06.5268] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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132
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Caldon CE, Daly RJ, Sutherland RL, Musgrove EA. Cell cycle control in breast cancer cells. J Cell Biochem 2006; 97:261-74. [PMID: 16267837 DOI: 10.1002/jcb.20690] [Citation(s) in RCA: 163] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In breast cancer, cyclins D1 and E and the cyclin-dependent kinase inhibitors p21 (Waf1/Cip1)and p27 (Kip1) are important in cell-cycle control and as potential oncogenes or tumor suppressor genes. They are regulated in breast cancer cells following mitogenic stimuli including activation of receptor tyrosine kinases and steroid hormone receptors, and their deregulation frequently impacts on breast cancer outcome, including response to therapy. The cyclin-dependent kinase inhibitor p16 (INK4A) also has a critical role in transformation of mammary epithelial cells. In addition to their roles in cell cycle control, some of these molecules, particularly cyclin D1, have actions that are not mediated through regulation of cyclin-dependent kinase activity but may be important for loss of proliferative control during mammary oncogenesis.
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Affiliation(s)
- C Elizabeth Caldon
- Cancer Research Program, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, NSW 2010, Australia
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133
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Nahta R, Esteva FJ. Herceptin: mechanisms of action and resistance. Cancer Lett 2006; 232:123-38. [PMID: 16458110 DOI: 10.1016/j.canlet.2005.01.041] [Citation(s) in RCA: 310] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2005] [Accepted: 01/30/2005] [Indexed: 11/28/2022]
Abstract
HER-2 is overexpressed in 20-25% of invasive breast cancers and is associated with an aggressive tumor phenotype and reduced survival rate. The HER-2 status of a tumor is the critical determinant of response to the HER-2-targeted antibody Herceptin. Thus, accurate assessment of HER-2 expression levels is essential for identifying breast cancer patients who will benefit from HER-2-targeted therapy. Herceptin combined with chemotherapy increases response rates, time to disease progression, and survival. However, the majority of cancers that initially respond to Herceptin begin to progress again within 1 year. This review describes mechanisms by which Herceptin inhibits cell growth in breast cancers that overexpress HER-2 and highlights possible mechanisms contributing to Herceptin resistance.
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Affiliation(s)
- Rita Nahta
- Department of Breast Medical Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, TX 77030-4009, USA
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134
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Ocaña A, Cruz JJ, Pandiella A. Trastuzumab and antiestrogen therapy: focus on mechanisms of action and resistance. Am J Clin Oncol 2006; 29:90-5. [PMID: 16462510 DOI: 10.1097/01.coc.0000190274.00570.0a] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
OBJECTIVE In breast cancer, 2 molecular targets are well established (ER/PR and HER2), and therapies directed to these proteins have demonstrated to be clinically useful. METHODS Despite the presence of the ER and PR, only half of the patients will respond to endocrine therapy, and less than 35% of patients with ErbB2-overexpressing metastatic breast cancer will respond to trastuzumab as a single agent. RESULTS To improve survival of metastatic breast cancer patients with ER/PR positive and HER2 positive is critical to elucidate the mechanism of resistance or sensitivity of these tumors for a better selection depending on biologic molecular alterations. CONCLUSIONS Recently, several studies addressing this issue have been reported. Here, we will focus on a comprehensive review of the currently available data.
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Affiliation(s)
- Alberto Ocaña
- Servicio de Oncología Médica, Hospital Universitario de Salamanca, Salamanca, Spain.
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135
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Kamath S, Buolamwini JK. Targeting EGFR and HER-2 receptor tyrosine kinases for cancer drug discovery and development. Med Res Rev 2006; 26:569-94. [PMID: 16788977 DOI: 10.1002/med.20070] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Conventional anticancer therapy using cytotoxic drugs lacks selectivity and is prone to toxicity and drug resistance. Anticancer therapies targeting aberrant growth factor receptor signaling are gaining interest. The erbB receptor family belongs to the type I, the receptor tyrosine kinases class, and comprises EGFR, HER-2, HER-3, and HER-4. It has been targeted for solid tumor therapy, including breast, ovarian, colon, head-and-neck, and non-small-cell lung cancers. This review summarizes structural aspects of this class of growth factor receptors, their oncogenic expression, and various pharmacological interventions including biological products and small molecules that inhibit these enzymes. We have also discussed various mutations that occur in EGFR and their consequences on anticancer therapy.
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Affiliation(s)
- Shantaram Kamath
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
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136
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Boulay A, Rudloff J, Ye J, Zumstein-Mecker S, O'Reilly T, Evans DB, Chen S, Lane HA. Dual inhibition of mTOR and estrogen receptor signaling in vitro induces cell death in models of breast cancer. Clin Cancer Res 2005; 11:5319-28. [PMID: 16033851 DOI: 10.1158/1078-0432.ccr-04-2402] [Citation(s) in RCA: 294] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE RAD001 (everolimus), a mammalian target of rapamycin (mTOR) pathway inhibitor in phase II clinical trials in oncology, exerts potent antiproliferative/antitumor activities. Many breast cancers are dependent for proliferation on estrogens synthesized from androgens (i.e., androstenedione) by aromatase. Letrozole (Femara) is an aromatase inhibitor used for treatment of postmenopausal women with hormone-dependent breast cancers. The role of the mTOR pathway in estrogen-driven proliferation and effects of combining RAD001 and letrozole were examined in vitro in two breast cancer models. EXPERIMENTAL DESIGN The role of the mTOR pathway in estrogen response was evaluated in aromatase-expressing MCF7/Aro breast cancer cells by immunoblotting. Effects of RAD001 and letrozole (alone and in combination) on the proliferation and survival of MCF7/Aro and T47D/Aro cells were evaluated using proliferation assays, flow cytometry, immunoblotting, and apoptosis analyses. RESULTS Treatment of MCF7/Aro cells with estradiol or androstenedione caused modulation of the mTOR pathway, a phenomenon reversed by letrozole or RAD001. In MCF7/Aro and T47D/Aro cells, both agents inhibited androstenedione-induced proliferation; however, in combination, this was significantly augmented (P < 0.001, two-way ANOVA, synergy by isobologram analysis). Increased activity of the combination correlated with more profound effects on G1 progression and a significant decrease in cell viability (P < 0.01, two-way ANOVA) defined as apoptosis (P < 0.05, Friedman test). Increased cell death was particularly evident with optimal drug concentrations. CONCLUSION mTOR signaling is required for estrogen-induced breast tumor cell proliferation. Moreover, RAD001-letrozole combinations can act in a synergistic manner to inhibit proliferation and trigger apoptotic cell death. This combination holds promise for the treatment of hormone-dependent breast cancers.
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Affiliation(s)
- Anne Boulay
- Novartis Institutes for BioMedical Research Basel, Oncology Research, Novartis Pharma AG, Basel, Switzerland
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137
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Yuste L, Montero JC, Esparís-Ogando A, Pandiella A. Activation of ErbB2 by Overexpression or by Transmembrane Neuregulin Results in Differential Signaling and Sensitivity to Herceptin. Cancer Res 2005; 65:6801-10. [PMID: 16061662 DOI: 10.1158/0008-5472.can-04-4023] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The ligands of the epidermal growth factor family and their receptors, the ErbB proteins, have been linked to the development of different types of cancer. Particular attention has focused on ErbB2, whose activation may occur by receptor overexpression or by ligand-induced oligomerization with other ErbB receptors. Whether these two modes of ErbB2 activation cause the same biological responses is unknown. Here, we uncovered important differences in the signaling, proliferation rates, and the response to anti-ErbB2 antibodies when comparing MCF7 cells expressing the ligand neuregulin, to MCF7 cells overexpressing ErbB2. Expression of neuregulin caused higher proliferation than ErbB2 overexpression. Transmembrane neuregulin expression was accompanied by constitutive activation of ErbB2, ErbB3, and ErbB4 receptors. ErbB2 overexpression caused tyrosine phosphorylation of ErbB2, whereas ErbB3 and ErbB4 were only slightly tyrosine phosphorylated. Autocrine transmembrane neuregulin also caused constitutive activation of several signaling pathways, such as the Erk1/2, Erk5, and Akt routes, which have been linked to breast cancer cell proliferation. Interestingly, expression of neuregulin increased p21 levels and this was required for the proliferation of MCF7 cells. Treatment with the anti-ErbB2 receptor antibody Herceptin had an inhibitory effect on proliferation only in cells expressing neuregulin but not on cells overexpressing ErbB2, and its inhibitory activity was accompanied by a decrease in p21. These results suggest that Herceptin may also be of help in the treatment of tumors in which neuregulin feeds the tumoral tissue.
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Affiliation(s)
- Laura Yuste
- Instituto de Microbiología Bioquímica and Centro de Investigación del Cáncer, CSIC, Universidad de Salamanca, Salamanca, Spain
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138
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Chan CT, Metz MZ, Kane SE. Differential sensitivities of trastuzumab (Herceptin)-resistant human breast cancer cells to phosphoinositide-3 kinase (PI-3K) and epidermal growth factor receptor (EGFR) kinase inhibitors. Breast Cancer Res Treat 2005; 91:187-201. [PMID: 15868447 DOI: 10.1007/s10549-004-7715-1] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Her2 (erbB2/neu) is overexpressed in 25-30% of human breast cancers. Herceptin is a recombinant humanized Her2 antibody used to treat breast cancer patients with Her2 overexpression. Over a 5-month selection process, we isolated clones of BT474 (BT) human breast carcinoma cells (BT/Her(R)) that were resistant to Herceptin in vitro. In BT/Her(R) subclones, cell-surface, phosphorylated and total cellular Her2 protein remained high in the continuous presence of Herceptin. Likewise, the levels of cell-surface, phosphorylated, and total cellular Her3 and EGFR were either unchanged or only slightly elevated in BT/Her(R) subclones relative to BT cells. One BT/Her(R) subclone had substantially upregulated cell-surface EGFR, but this did not correlate with a higher relative resistance to Herceptin. In looking at the downstream PI-3K/Akt signaling pathway, phosphorylated and total Akt levels and Akt kinase activities were all sustained in BT/Her(R) subclones in the presence of Herceptin, but significantly downregulated in BT cells exposed to Herceptin. Whereas BT cells lost sensitivity to the PI-3K inhibitor LY294002 in the presence of Herceptin, BT/Her(R) subclones were equally sensitive to this agent in the presence and absence of Herceptin. This suggests that BT/Her(R) subclones acquired a Herceptin-resistant mechanism of PI-3K signaling. BT/Her(R) subclones were also sensitive to the EGFR kinase inhibitor AG1478 in the presence of Herceptin, to the same extent as BT cells. The BT/Her(R) subclones provide new insights into mechanisms of Herceptin resistance and suggest new treatment strategies in combination with other inhibitors targeted to signal transduction pathways.
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Affiliation(s)
- Carmel T Chan
- Division of Molecular Medicine, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA
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139
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Hu YP, Venkateswarlu S, Sergina N, Howell G, St Clair P, Humphrey LE, Li W, Hauser J, Zborowska E, Willson JKV, Brattain MG. Reorganization of ErbB family and cell survival signaling after Knock-down of ErbB2 in colon cancer cells. J Biol Chem 2005; 280:27383-92. [PMID: 15888451 DOI: 10.1074/jbc.m414238200] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The role of the ErbB family in supporting the malignant phenotype was characterized by stable transfection of a single chain antibody (ScFv5R) against ErbB2 containing a KDEL endoplasmic reticulum retention sequence into GEO human colon carcinoma cells. The antibody traps ErbB2 in the endoplasmic reticulum, thereby down-regulating cell surface ErbB2. The transfected cells showed inactivation of ErbB2 tyrosine phosphorylation and reduced heterodimerization of ErbB2 and ErbB3. This resulted in greater sensitivity to apoptosis induced by growth deprivation and delayed tumorigenicity in vivo. Furthermore, decreased heterodimerization of ErbB2 and ErbB3 led to a reorganization in ErbB function in transfected cells as heterodimerization between epidermal growth factor receptor (EGFR) and ErbB3 increased, whereas ErbB3 activation remained almost the same. Importantly, elimination of ErbB2 signaling resulted in an increase in EGFR expression and activation in transfected cells. Increased EGFR activation contributed to the sustained cell survival in transfected cells.
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Affiliation(s)
- Yi Peter Hu
- Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263, USA
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140
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Abstract
ERBB receptor tyrosine kinases have important roles in human cancer. In particular, the expression or activation of epidermal growth factor receptor and ERBB2 are altered in many epithelial tumours, and clinical studies indicate that they have important roles in tumour aetiology and progression. Accordingly, these receptors have been intensely studied to understand their importance in cancer biology and as therapeutic targets, and many ERBB inhibitors are now used in the clinic. We will discuss the significance of these receptors as clinical targets, in particular the molecular mechanisms underlying response.
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Affiliation(s)
- Nancy E Hynes
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland.
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141
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MacKeigan JP, Murphy LO, Blenis J. Sensitized RNAi screen of human kinases and phosphatases identifies new regulators of apoptosis and chemoresistance. Nat Cell Biol 2005; 7:591-600. [PMID: 15864305 DOI: 10.1038/ncb1258] [Citation(s) in RCA: 408] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2005] [Accepted: 04/19/2005] [Indexed: 01/09/2023]
Abstract
Evasion from apoptosis is a hallmark of cancer, and recent success using targeted therapeutics underscores the importance of identifying anti-apoptotic survival pathways. Here we utilize RNA interference (RNAi) to systematically screen the kinase and phosphatase component of the human genome. In addition to known kinases, we identified several new survival kinases. Interestingly, numerous phosphatases and associated regulatory subunits contribute to cell survival, revealing a previously unrecognized general role for phosphatases as negative regulators of apoptosis. We also identified a subset of phosphatases with tumour-suppressor-like activity. Finally, RNAi targeting of specific protein kinases sensitizes resistant cells to chemotherapeutic agents. The development of inhibitors that target these kinases or phosphatases may lead to new anti-cancer strategies.
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Affiliation(s)
- Jeffrey P MacKeigan
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, USA
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142
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Köstler WJ, Brodowicz T, Hudelist G, Rudas M, Horvat R, Steger GG, Singer CF, Attems J, Rabitsch W, Fakhrai N, Elandt K, Wiltschke C, Hejna M, Zielinski CC. The efficacy of trastuzumab in Her-2/neu-overexpressing metastatic breast cancer is independent of p53 status. J Cancer Res Clin Oncol 2005; 131:420-8. [PMID: 15864644 DOI: 10.1007/s00432-005-0670-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2004] [Accepted: 01/10/2005] [Indexed: 11/24/2022]
Abstract
PURPOSE Her-2/neu and p53-mediated signalling have been shown to interact at various cellular levels. However, the clinical relevance of p53 alterations in patients receiving trastuzumab for Her-2/neu-overexpressing metastatic breast cancer (MBC) remains unknown. The present study was performed to corroborate previous in vitro findings from our laboratory showing that trastuzumab induces growth arrest and apoptosis in a p53-independent manner. METHOD Retrospective immunohistochemical (IHC) analysis for p53 protein expression was carried out on tumour specimens from 104 patients receiving trastuzumab-based treatment for Her-2/neu-overexpressing MBC at a single institution. p53 status was correlated with response (R) and clinical benefit (CB), median progression-free survival (PFS) time and overall survival (OAS) time in univariate and multivariate analyses. RESULTS Characteristics were similar between p53-negative and p53-positive tumours (all P>0.05). In univariate analyses, R (39% vs 26%, P=0.208), CB (70% vs 57%, P=0.218), PFS (6.2 months vs 4.2 months, P=0.186) and OAS (23.8 months vs 23.2 months, P=0.650) were similar for p53-positive tumours and p53-negative tumours, respectively. In multivariate analyses, p53 status was not a significant predictor of R, CB, PFS or OAS (all P>0.05). CONCLUSIONS p53 status, as determined by IHC, is not a predictor of the clinical efficacy of trastuzumab-based treatment in patients with Her-2/neu-overexpressing MBC.
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MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Antibodies, Monoclonal/therapeutic use
- Antibodies, Monoclonal, Humanized
- Antineoplastic Agents/therapeutic use
- Biomarkers, Tumor/metabolism
- Breast Neoplasms/drug therapy
- Breast Neoplasms/metabolism
- Breast Neoplasms/secondary
- Carcinoma, Ductal, Breast/drug therapy
- Carcinoma, Ductal, Breast/metabolism
- Carcinoma, Ductal, Breast/secondary
- Female
- Humans
- Middle Aged
- Prognosis
- Receptor, ErbB-2/metabolism
- Retrospective Studies
- Survival Rate
- Trastuzumab
- Treatment Outcome
- Tumor Suppressor Protein p53/metabolism
- Up-Regulation
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Affiliation(s)
- Wolfgang J Köstler
- Clinical Division of Oncology, Department of Medicine I, Medical University of Vienna, 18-20 Waehringer Guertel, 1090, Vienna, Austria.
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143
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Way TD, Kao MC, Lin JK. Degradation of HER2/neu by apigenin induces apoptosis through cytochrome c release and caspase-3 activation in HER2/neu-overexpressing breast cancer cells. FEBS Lett 2005; 579:145-52. [PMID: 15620704 DOI: 10.1016/j.febslet.2004.11.061] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2004] [Revised: 11/12/2004] [Accepted: 11/15/2004] [Indexed: 11/16/2022]
Abstract
We have shown that exposure of the HER2/neu-overexpressing breast cancer cells to apigenin resulted in induction of apoptosis by depleting HER2/neu protein and, in turn, suppressing the signaling of the HER2/HER3-PI3K/Akt pathway. Here, we examined whether inhibition of this pathway played a role in the anti-tumor effect. The results revealed that treatment with apigenin induced apoptosis through cytochrome c release and caused a rapid induction of caspase-3 activity and stimulated proteolytic cleavage of DFF-45. Furthermore, apigenin downregulated cyclin D1, D3 and Cdk4 and increased p27 protein levels. Colony formation in the soft agar assay, a hallmark of the transformation phenotype, was preferentially suppressed in HER2/neu-overexpressing breast cancer cells in the presence of apigenin. In addition, a structure-activity relationship study indicated that (1) the position of B ring; and (2) the existence of the 3', 4'-hydroxyl group on the 2-phenyl group were important for the depletion of HER2/neu protein by flavonoids. These results provided new insights into the structure-activity relationship of flavonoids.
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Affiliation(s)
- Tzong-Der Way
- Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, No. 1, Section 1, Jen-ai Road, Taipei 10018, Taiwan
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144
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Premature Senescence Is a Primary Fail-safe Mechanism of ERBB2-Driven Tumorigenesis in Breast Carcinoma Cells. Cancer Res 2005. [DOI: 10.1158/0008-5472.840.65.3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
The receptor tyrosine kinase ERBB2 plays a central role in the development of breast cancer and other epithelial malignancies. Elevated ERBB2 activity is believed to transform cells by transmitting mitogenic and antiapoptotic signals. Here we show that tightly regulated overexpression of oncogenic ERBB2 in human breast carcinoma cells does not stimulate proliferation but provokes premature senescence, accompanied by up-regulation of the cyclin-dependent kinase inhibitor P21WAF1/CIP1. A similar effect was caused by retrovirus-mediated overexpression of oncogenic ERBB2 in low-passage murine embryonic fibroblasts. In contrast to previous observations based on constitutively overexpressing cell lines, P21 induced by tetracycline-regulated ERBB2 localizes to the nucleus in arrested cells. P21 up-regulation seems to be independent of the P53 tumor suppressor protein, and senescence-associated phenotypic alterations are reversed by specific inhibition of P38 mitogen-activated protein kinases. Functional inactivation of P21 by antisense oligonucleotides is sufficient to prevent cell cycle arrest as well as the senescent phenotype, thereby identifying the P21 protein as the key mediator of hypermitogenic cell cycle arrest and premature senescence in breast carcinoma cells. Our results may thus indicate that premature senescence represents an inherent anticarcinogenic program during ERBB2-driven mammary tumorigenesis. We propose a multistep model for the process of malignant transformation by ERBB2 wherein secondary lesions either target P21 or downstream effectors of senescence to bypass this primary fail-safe mechanism.
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145
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Diermeier S, Horváth G, Knuechel-Clarke R, Hofstaedter F, Szöllosi J, Brockhoff G. Epidermal growth factor receptor coexpression modulates susceptibility to Herceptin in HER2/neu overexpressing breast cancer cells via specific erbB-receptor interaction and activation. Exp Cell Res 2005; 304:604-19. [PMID: 15748904 DOI: 10.1016/j.yexcr.2004.12.008] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2004] [Revised: 12/07/2004] [Accepted: 12/08/2004] [Indexed: 12/25/2022]
Abstract
BACKGROUND Growth factors and Herceptin specifically and differentially modulate cell proliferation of tumor cells. However, the mechanism of action on erbB-receptor level is incompletely understood. We evaluated Herceptin's capacity to modulate erbB-receptor activation and interaction on the cell surface level and thereby potentially impair cell proliferation of HER2/neu (c-erbB2) overexpressing breast cancer cells, both in the presence and absence of relevant growth factors. METHODS BT474 and SK-BR-3 breast cancer cell lines were treated with Epidermal Growth Factor (EGF), Heregulin, and with Herceptin in different combinations. Kinetics of cell proliferation were evaluated flow cytometrically based on BrdU-labeling. Fluorescence Resonance Energy Transfer, ELISAs and phosphorylation site specific Western Blotting was performed to investigate erbB-receptor interaction and activation. RESULTS EGF induced EGFR/EGFR and EGFR/c-erbB2 interactions correlate with stimulation of cell proliferation in BT474 cells. Both homo- and heterodimerization are considerably less pronounced in SK-BR-3 cells and heterointeraction is additionally reduced by EGF treatment, causing inhibition of cell proliferation. Heregulin stimulates cell proliferation extensively in both cell lines. Herceptin drives BT474 cells more efficiently into quiescence than it does with SK-BR-3 cells and thereby blocks cell cycle progress. In SK-BR-3 Herceptin treatment causes c-erbB2 phosphorylation of Y877 and Y1248, EGF induces Y877 and Y1112 phosphorylation. The Y1112 phosphorylation site, activated by EGF in SK-BR-3 cell, is bypassed in BT474. In addition the inhibitory capacity of Herceptin on BT474 and SK-BR-3 cell proliferation depends on the presence and absence of growth factors to a various extent. CONCLUSION The growth inhibitory effect of Herceptin on c-erbB2 overexpressing breast cancer cells is considerably modulated by EGFR coexpression and consequently EGFR/c-erbB2 homo- and heterointeractions, as well as the presence or absence of growth factors. C-erbB2 overexpression alone is insufficient to predict the impact of growth factors and antibodies on cell proliferation. The optimization and specification of therapeutic approaches based on erbB-receptor targeting requires to account for EGFR coexpression as well as the potential presence of erbB-receptor relevant growth factors.
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MESH Headings
- Antibodies, Monoclonal/metabolism
- Antibodies, Monoclonal/pharmacology
- Antibodies, Monoclonal/therapeutic use
- Antibodies, Monoclonal, Humanized
- Antineoplastic Agents/metabolism
- Antineoplastic Agents/pharmacology
- Antineoplastic Agents/therapeutic use
- Breast Neoplasms/drug therapy
- Breast Neoplasms/genetics
- Breast Neoplasms/metabolism
- Carcinoma/drug therapy
- Carcinoma/genetics
- Carcinoma/metabolism
- Cell Cycle/drug effects
- Cell Cycle/physiology
- Cell Cycle Proteins/metabolism
- Cell Cycle Proteins/pharmacology
- Cell Line, Tumor
- Cell Proliferation/drug effects
- Drug Resistance, Neoplasm/physiology
- Drug Synergism
- Epidermal Growth Factor/metabolism
- Epidermal Growth Factor/pharmacology
- ErbB Receptors/genetics
- ErbB Receptors/metabolism
- Female
- Growth Inhibitors/metabolism
- Growth Inhibitors/pharmacology
- Growth Inhibitors/therapeutic use
- Humans
- Neuregulin-1/metabolism
- Neuregulin-1/pharmacology
- Phosphorylation/drug effects
- Receptor, ErbB-2/genetics
- Receptor, ErbB-2/metabolism
- Receptors, Cell Surface/drug effects
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Trastuzumab
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Affiliation(s)
- Simone Diermeier
- Institute of Pathology, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany
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146
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Longva KE, Pedersen NM, Haslekås C, Stang E, Madshus IH. Herceptin-induced inhibition of ErbB2 signaling involves reduced phosphorylation of Akt but not endocytic down-regulation of ErbB2. Int J Cancer 2005; 116:359-67. [PMID: 15800944 DOI: 10.1002/ijc.21015] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The anti-proliferative effect of the ErbB2 specific antibody Herceptin in cells overexpressing ErbB2 has previously been explained by endocytic downregulation of ErbB2. However, in the following, we demonstrate that Herceptin inhibited proliferation of ErbB2 overexpressing cells without downregulating ErbB2. Herceptin did also not induce endocytosis of ErbB2. Herceptin was found to blunt proliferation of SKBr3 cells overexpressing EGFR, ErbB2, and ErbB3 and expressing functional PTEN, probably by recruiting PTEN to the plasma membrane. Akt was found to be constitutively phosphorylated both in SKBr3 cells overexpressing EGFR, ErbB2 and ErbB3, and in SKOv3 cells, overexpressing EGFR and ErbB2. However, phosphorylation of Akt was inhibited by Herceptin only in SKBr3 cells. SKOv3 cells, which lack the tumour suppressor protein Ras homolog member I, was found to have constitutively phosphorylated mitogen activated protein kinase and functionally increased Ras activity. SKOv3 cells further had low expression levels of PTEN. We thus confirm that the anti-proliferative effect of Herceptin in SKBr3 cells is due to recruitment of PTEN to the plasma membrane and conclude that Herceptin does not blunt phosphatidyl inositol 3 kinase-induced growth in cells with constitutive Ras activity. We further conclude that endocytic downregulation of ErbB2 does not contribute to Herceptin's antiproliferative effect.
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Affiliation(s)
- Karianne E Longva
- Institute of Pathology, The University of Oslo, Rikshospitalet, Oslo, Norway
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147
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Chu I, Blackwell K, Chen S, Slingerland J. The Dual ErbB1/ErbB2 Inhibitor, Lapatinib (GW572016), Cooperates with Tamoxifen to Inhibit Both Cell Proliferation- and Estrogen-Dependent Gene Expression in Antiestrogen-Resistant Breast Cancer. Cancer Res 2005. [DOI: 10.1158/0008-5472.18.65.1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Effective treatment of estrogen receptor (ER)-positive breast cancers with tamoxifen is often curtailed by the development of drug resistance. Antiestrogen-resistant breast cancers often show increased expression of the epidermal growth factor receptor family members, ErbB1 and ErbB2. Tamoxifen activates the cyclin-dependent kinase inhibitor, p27 to mediate G1 arrest. ErbB2 or ErbB1 overexpression can abrogate tamoxifen sensitivity in breast cancer lines through both reduction in p27 levels and inhibition of its function. Here we show that the dual ErbB1/ErbB2 inhibitor, lapatinib (GW572016), can restore tamoxifen sensitivity in ER-positive, tamoxifen-resistant breast cancer models. Treatment of MCF-7pr, T-47D, and ZR-75 cells with lapatinib or tamoxifen alone caused an incomplete cell cycle arrest. Treatment with both drugs led to a more rapid and profound cell cycle arrest in all three lines. Mitogen-activated protein kinase and protein kinase B were inhibited by lapatinib. The two drugs together caused a greater reduction of cyclin D1 and a greater p27 increase and cyclin E-cdk2 inhibition than observed with either drug alone. In addition to inhibiting mitogenic signaling and cell cycle progression, lapatinib inhibited estrogen-stimulated ER transcriptional activity and cooperated with tamoxifen to further reduce ER-dependent transcription. Lapatinib in combination with tamoxifen effectively inhibited the growth of tamoxifen-resistant ErbB2 overexpressing MCF-7 mammary tumor xenografts. These data provide strong preclinical data to support clinical trials of ErbB1/ErbB2 inhibitors in combination with tamoxifen in the treatment of human breast cancer.
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Affiliation(s)
- Isabel Chu
- 1The Braman Breast Cancer Institute, UM Sylvester Comprehensive Cancer Center and
- 3Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada; and
| | - Kimberly Blackwell
- 4Division of Medical Oncology, Department of Medicine, Duke University Comprehensive Cancer Center, Durham, North Carolina
| | - Susie Chen
- 1The Braman Breast Cancer Institute, UM Sylvester Comprehensive Cancer Center and
| | - Joyce Slingerland
- 1The Braman Breast Cancer Institute, UM Sylvester Comprehensive Cancer Center and
- 2Department of Biochemistry and Molecular Biology, University of Miami School of Medicine, Miami, Florida
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148
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Warburton C, Dragowska WH, Gelmon K, Chia S, Yan H, Masin D, Denyssevych T, Wallis AE, Bally MB. Treatment of HER-2/neu overexpressing breast cancer xenograft models with trastuzumab (Herceptin) and gefitinib (ZD1839): drug combination effects on tumor growth, HER-2/neu and epidermal growth factor receptor expression, and viable hypoxic cell fraction. Clin Cancer Res 2004; 10:2512-24. [PMID: 15073131 DOI: 10.1158/1078-0432.ccr-03-0244] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE The purpose of this research was to assess the effects of single agent and combination treatment with trastuzumab and gefitinib on tumor growth and tumor microenvironment in two HER-2/neu overexpressing breast xenograft models, MDA-MB-435/LCC6(HER-2) (LCC6(HER-2); estrogen receptor negative) and MCF-7(HER-2) (estrogen receptor positive). EXPERIMENTAL DESIGN LCC6(HER-2) and MCF-7(HER-2) cells, both in tissue culture and xenografts grown in SCID-Rag 2M mice, were treated with trastuzumab and gefitinib, alone or in combination. The rate of tumor growth was determined. In addition, tumor HER-2/neu and epidermal growth factor receptor expression, cell viability, cell cycle distribution, and proportion of viable hypoxic cells were determined by flow cytometric analyses of single tumor cell suspensions. RESULTS Both tumor models were very sensitive to trastuzumab and moderately sensitive to gefitinib in vivo. The combination resulted in therapeutic effects, as judged by inhibition of tumor growth, which was greater (albeit not statistically significant) than that observed with trastuzumab administered as a single agent. Trastuzumab was effective in down-regulating HER-2/neu, and gefitinib mediated a reduction in epidermal growth factor receptor expression on tumor cells. In LCC6(HER-2) tumors, trastuzumab significantly reduced tumor cell viability, which was not improved by the addition of gefitinib. Gefitinib dramatically reduced the proportion of viable hypoxic cells in LCC6(HER-2) and MCF-7(HER-2) tumors. This effect was abrogated by the addition of trastuzumab. CONCLUSIONS Although in vivo efficacy studies in two HER-2/neu overexpressing breast xenograft models showed that the combination of trastuzumab and gefitinib was effective, analyses of various cellular parameters failed to reveal beneficial effects and argue that this drug combination may not be favorable.
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Affiliation(s)
- Corinna Warburton
- Department of Advanced Therapeutics, British Columbia Cancer Agency, Vancouver, Canada
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149
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Abstract
Activation of intracellular mitogenic signal transduction pathways driven by the ErbB family of receptor tyrosine kinases has been implicated in a variety of cancers. Amongst these, the tumorigenic roles of the Epidermal Growth Factor receptor (EGFR) and HER-2 have been most extensively studied. Therapeutic antibodies and small molecule kinase inhibitors targeting EGFR have recently received regulatory agency approval for the treatment of colon and lung cancer, respectively. In this review, I briefly describe these agents and their potential use in inhibiting the growth of tumors that overexpress HER-2. I also discuss other therapeutics currently available or being developed specifically to target HER-2 dependent tumors.
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150
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Faltus T, Yuan J, Zimmer B, Krämer A, Loibl S, Kaufmann M, Strebhardt K. Silencing of the HER2/neu gene by siRNA inhibits proliferation and induces apoptosis in HER2/neu-overexpressing breast cancer cells. Neoplasia 2004; 6:786-95. [PMID: 15720805 PMCID: PMC1531682 DOI: 10.1593/neo.04313] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2004] [Revised: 07/29/2004] [Accepted: 08/06/2004] [Indexed: 11/18/2022]
Abstract
In eukaryotes, double-stranded (ds) RNA induces sequence-specific inhibition of gene expression referred to as RNA interference (RNAi). We exploited RNAi to define the role of HER2/neu in the neoplastic proliferation of human breast cancer cells. We transfected SK-BR-3, BT-474, MCF-7, and MDA-MB-468 breast cancer cells with short interfering RNA (siRNA) targeted against human HER2/neu and analyzed the specific inhibition of HER2/neu expression by Northern and Western blots. Transfection with HER2/neu-specific siRNA resulted in a sequence-specific decrease in HER2/neu mRNA and protein levels. Moreover, transfection with HER2/neu siRNA caused cell cycle arrest at G0/G1 in the breast cancer cell lines SK-BR-3 and BT-474, consistent with a powerful RNA silencing effect. siRNA treatment resulted in an antiproliferative and apoptotic response in cells overexpressing HER2/neu, but had no influence in cells with almost no expression of HER2/neu proteins like MDA-MB-468 cells. These data indicate that HER2/neu function is essential for the proliferation of HER2/neu-overexpressing breast cancer cells. Our observations suggest that siRNA targeted against human HER2/neu may be valuable tools as antiproliferative agents that display activity against neoplastic cells at very low doses.
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Affiliation(s)
- Timo Faltus
- Department of Obstetrics and Gynecology, Medical School, J. W. Goethe University, Theodor-Stern-Kai 7, Frankfurt 60590, Germany
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