101
|
|
102
|
Abstract
INTRODUCTION Recent studies suggested that p95HER2, the NH2-terminally truncated form of human epidermal growth factor receptor 2 (HER2), could confer resistance to monoclonal antibodies against HER2 (HER2-mab). The aim of this study was to investigate the role of p95HER2 according to HER2 gene copy number (GCN) and HER2 mutation in non-small cell lung cancer (NSCLC). METHODS The study included 447 resected NSCLC patients evaluated for P95HER2 status by immunofluorescence. Data were correlated with HER2 GCN evaluated by fluorescence in situ hybridization (FISH) and HER2 mutations. Tumors were scored as positive for p95HER2 expression if any cytoplasmic staining was detected. RESULTS P95HER2 was successfully evaluated in 431 patients and was positive (p95HER2+) in 33 (7.6%) cases. HER2 GCN was evaluable in 439 patients, and increased GCN (at least four copies in at least 40% cells) was found in 60 cases, of which 22 (5.0%) displayed gene amplification (GA). Among the 22 patients with HER2 amplification, only one resulted P95HER2+. To further investigate whether the receptor is truncated in presence of gene mutation, in addition to the study cohort, we analyzed p95HER2 status in eight NSCLC samples harboring HER2 mutation, and only one case resulted p95HER2+. In the whole population, p95HER2- patients had numerically higher risk of death than p95HER2+ (hazard ratio = 1.4, p = 0.2). No difference in survival was observed between patients with or without HER2 GA (median 38 versus 41 months, p = 0.46). HER2 GA was significantly associated with EGFR and MET GA, with no effect on survival. CONCLUSIONS HER2 truncation and HER2 increased GCN are not prognostic in resected NSCLC. P95HER2 is a very rare event in individuals displaying HER2 gene amplification or mutation.
Collapse
|
103
|
Generation of a new bioluminescent model for visualisation of mammary tumour development in transgenic mice. BMC Cancer 2012; 12:209. [PMID: 22646761 PMCID: PMC3411433 DOI: 10.1186/1471-2407-12-209] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Accepted: 05/10/2012] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Numerous transgenic models have been generated to study breast cancer. However, despite many advantages, traditional transgenic models for breast cancer are also burdened with difficulties in early detection and longitudinal observation of transgene-induced tumours, which in most cases are randomly located and occur at various time points. Methods such as palpation followed by mechanical measurement of the tumours are of limited value in transgenic models. There is a crucial need for making these previously generated models suitable for modern methods of tumour visualisation and monitoring, e.g. by bioluminescence-based techniques. This approach was successfully used in the current study. RESULTS A new mouse strain (MMTV-Luc2 mice) expressing Luc2 luciferase primarily in mammary tissue in females, with low-level background expression in internal organs, was generated and bred to homozygosity. After these mice were intercrossed with MMTV-PyVT mice, all double transgenic females developed mammary tumours by the age of 10 weeks, the localisation and progression of which could be effectively monitored using the luminescence-based in vivo imaging. Luminescence-based readout allowed for early visualisation of the locally overgrown mammary tissue and for longitudinal evaluation of local progression of the tumours. When sampled ex vivo at the age of 10 weeks, all tumours derived from MMTV-Luc2PyVT females displayed robust bioluminescent signal. CONCLUSIONS We have created a novel transgenic strain for visualisation and longitudinal monitoring of mammary tumour development in transgenic mice as an addition and/or a new and more advanced alternative to manual methods. Generation of this mouse strain is vital for making many of the existing mammary tumour transgenic models applicable for in vivo imaging techniques.
Collapse
|
104
|
A dominant-negative N-terminal fragment of HER2 frequently expressed in breast cancers. Oncogene 2012; 32:1452-9. [DOI: 10.1038/onc.2012.152] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
|
105
|
Wong ALA, Lee SC. Mechanisms of Resistance to Trastuzumab and Novel Therapeutic Strategies in HER2-Positive Breast Cancer. Int J Breast Cancer 2012; 2012:415170. [PMID: 22649737 PMCID: PMC3357513 DOI: 10.1155/2012/415170] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Accepted: 02/03/2012] [Indexed: 12/20/2022] Open
Abstract
HER2-positive breast cancers have poorer prognosis and are prime candidates for molecular-targeted therapy because they are driven by the unique mechanism of HER2 oncogene addiction. While anti-HER2 agents such as trastuzumab and lapatinib are integral to the treatment of HER2-positive breast cancer, intrinsic and secondary resistance pose a significant challenge, underscoring the need to develop novel anti-HER2 therapies. In recent years, an array of promising and novel anti-HER2 therapeutic agents and their combinations have entered various stages of clinical development. However, questions remain on the optimal sequences of HER2-directed therapies and selection of patients for the most appropriate drug or combinations; incompletely defined mechanisms of trastuzumab action and resistance have also dampened the progress of more successful biomarker-driven treatment approaches. This paper summarizes existing preclinical and clinical evidence on the mechanisms of trastuzumab action and resistance and provides an up-to-date overview of novel HER2-directed therapies in clinical development.
Collapse
Affiliation(s)
- Andrea L. A. Wong
- Department of Haematology-Oncology, National University Cancer Institute, National University Health System, Singapore 119228
| | - Soo-Chin Lee
- Department of Haematology-Oncology, National University Cancer Institute, National University Health System, Singapore 119228
- Cancer Science Institute, National University of Singapore, Singapore 117599
| |
Collapse
|
106
|
Aydoğdu E, Katchy A, Tsouko E, Lin CY, Haldosén LA, Helguero L, Williams C. MicroRNA-regulated gene networks during mammary cell differentiation are associated with breast cancer. Carcinogenesis 2012; 33:1502-11. [PMID: 22562546 DOI: 10.1093/carcin/bgs161] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
MicroRNAs (miRNAs) play pivotal roles in stem cell biology, differentiation and oncogenesis and are of high interest as potential breast cancer therapeutics. However, their expression and function during normal mammary differentiation and in breast cancer remain to be elucidated. In order to identify which miRNAs are involved in mammary differentiation, we thoroughly investigated miRNA expression during functional differentiation of undifferentiated, stem cell-like, murine mammary cells using two different large-scale approaches followed by qPCR. Significant changes in expression of 21 miRNAs were observed in repeated rounds of mammary cell differentiation. The majority, including the miR-200 family and known tumor suppressor miRNAs, was upregulated during differentiation. Only four miRNAs, including oncomiR miR-17, were downregulated. Pathway analysis indicated complex interactions between regulated miRNA clusters and major pathways involved in differentiation, proliferation and stem cell maintenance. Comparisons with human breast cancer tumors showed the gene profile from the undifferentiated, stem-like stage clustered with that of poor-prognosis breast cancer. A common nominator in these groups was the E2F pathway, which was overrepresented among genes targeted by the differentiation-induced miRNAs. A subset of miRNAs could further discriminate between human non-cancer and breast cancer cell lines, and miR-200a/miR-200b, miR-146b and miR-148a were specifically downregulated in triple-negative breast cancer cells. We show that miR-200a/miR-200b can inhibit epithelial-mesenchymal transition (EMT)-characteristic morphological changes in undifferentiated, non-tumorigenic mammary cells. Our studies propose EphA2 as a novel and important target gene for miR-200a. In conclusion, we present evidentiary data on how miRNAs are involved in mammary cell differentiation and indicate their related roles in breast cancer.
Collapse
Affiliation(s)
- Eylem Aydoğdu
- Department of Biology and Biochemistry, Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, TX 77204, USA
| | | | | | | | | | | | | |
Collapse
|
107
|
Tsé C, Gauchez AS, Jacot W, Lamy PJ. HER2 shedding and serum HER2 extracellular domain: Biology and clinical utility in breast cancer. Cancer Treat Rev 2012; 38:133-42. [DOI: 10.1016/j.ctrv.2011.03.008] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 03/28/2011] [Accepted: 03/31/2011] [Indexed: 01/29/2023]
|
108
|
Wilken JA, Badri T, Cross S, Raji R, Santin AD, Schwartz P, Branscum AJ, Baron AT, Sakhitab AI, Maihle NJ. EGFR/HER-targeted therapeutics in ovarian cancer. Future Med Chem 2012; 4:447-69. [PMID: 22416774 PMCID: PMC4620931 DOI: 10.4155/fmc.12.11] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Despite decades of research and evolving treatment modalities, survival among patients with epithelial ovarian cancer has improved only incrementally. During this same period, the development of biologically targeted therapeutics has improved survival for patients with diverse malignancies. Many of these new drugs target the human epidermal growth factor receptor (EGFR/HER/ErbB) family of tyrosine kinases, which play a major role in the etiology and progression of many carcinomas, including epithelial ovarian cancer. While several HER-targeted therapeutics are US FDA approved for the treatment of various malignancies, none have gained approval for the treatment of ovarian cancer. Here, we review the published literature on HER-targeted therapeutics for the treatment of ovarian cancer, including novel HER-targeted therapeutics in various stages of clinical development, as well as the challenges that have limited the use of these inhibitors in clinical settings.
Collapse
Affiliation(s)
- Jason A Wilken
- Yale University, Department of Obstetrics, Gynecology & Reproductive Sciences
| | - Tayf Badri
- Yale University, Department of Obstetrics, Gynecology & Reproductive Sciences
| | - Sarah Cross
- Yale University, Department of Obstetrics, Gynecology & Reproductive Sciences
| | - Rhoda Raji
- Yale University, Department of Obstetrics, Gynecology & Reproductive Sciences
| | - Alessandro D Santin
- Yale University, Department of Obstetrics, Gynecology & Reproductive Sciences
| | - Peter Schwartz
- Yale University, Department of Obstetrics, Gynecology & Reproductive Sciences
| | - Adam J Branscum
- Oregon State University, School of Biological & Population Health Sciences
| | - Andre T Baron
- University of Kentucky, Departments of Epidemiology, & Obstetrics & Gynecology
| | - Adam I Sakhitab
- Yale University, Department of Obstetrics, Gynecology & Reproductive Sciences
| | - Nita J Maihle
- Yale University, Department of Obstetrics, Gynecology & Reproductive Sciences
- Yale University, Departments of Pathology & Pharmacology
- PO Box 208063, 333 Cedar Street, New Haven, CT 06520, USA
| |
Collapse
|
109
|
Ciravolo V, Huber V, Ghedini GC, Venturelli E, Bianchi F, Campiglio M, Morelli D, Villa A, Della Mina P, Menard S, Filipazzi P, Rivoltini L, Tagliabue E, Pupa SM. Potential role of HER2-overexpressing exosomes in countering trastuzumab-based therapy. J Cell Physiol 2012; 227:658-67. [PMID: 21465472 DOI: 10.1002/jcp.22773] [Citation(s) in RCA: 357] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Exosomes are endosome-derived nanovesicles actively released into the extracellular environment and biological fluids, both under physiological and pathological conditions, by different cell types. We characterized exosomes constitutively secreted by HER2-overexpressing breast carcinoma cell lines and analyzed in vitro and in vivo their potential role in interfering with the therapeutic activity of the humanized antibody Trastuzumab and the dual tyrosine kinase inhibitor (TKI) Lapatinib anti-HER2 biodrugs. We show that exosomes released by the HER2-overexpressing tumor cell lines SKBR3 and BT474 express a full-length HER2 molecule that is also activated, although to a lesser extent than in the originating cells. Release of these exosomes was significantly modulated by the growth factors EGF and heregulin, two of the known HER2 receptor-activating ligands and naturally present in the surrounding tumor microenvironment. Exosomes secreted either in HER2-positive tumor cell-conditioned supernatants or in breast cancer patients' serum bound to Trastuzumab. Functional assays revealed that both xenogeneic and autologous HER2-positive nanovesicles, but not HER2-negative ones, inhibited Trastuzumab activity on SKBR3 cell proliferation. By contrast, Lapatinib activity on SKBR3 cell proliferation was unaffected by the presence of autologous exosomes. Together, these findings point to the role of HER2-positive exosomes in modulating sensitivity to Trastuzumab, and, consequently, to HER2-driven tumor aggressiveness.
Collapse
Affiliation(s)
- Valentina Ciravolo
- Molecular Targeting Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS, Istituto Nazionale Tumori, Milan, Italy
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
110
|
Bailey TA, Luan H, Clubb RJ, Naramura M, Band V, Raja SM, Band H. Mechanisms of Trastuzumab resistance in ErbB2-driven breast cancer and newer opportunities to overcome therapy resistance. J Carcinog 2011; 10:28. [PMID: 22190870 PMCID: PMC3243087 DOI: 10.4103/1477-3163.90442] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2011] [Accepted: 10/20/2011] [Indexed: 12/31/2022] Open
Abstract
The Human Epidermal Growth Factor Receptor 2 (Her2, ErbB2 or Neu) is overexpressed in about 20 – 25% of breast cancers and is causally linked to oncogenesis, providing opportunities for targeted therapy. Trastuzumab (Herceptin™, Genentech Inc, San Francisco, CA), a humanized monoclonal antibody against ErbB2, is a successful example of this concept and has vastly improved the response to treatment and overall survival in a majority of ErbB2+ breast cancer patients. However, lack of response in some patients as well as relapse during the course of therapy in others, continue to challenge researchers and clinicians alike towards a better understanding of the fundamental mechanisms of Trastuzumab action and resistance to treatment. The exact in vivo mechanism of action of Trastuzumab remains enigmatic, given its direct effects on the ErbB2 signaling pathway as well as indirect contributions from the immune system, by virtue of the ability of Trastuzumab to elicit Antibody-Dependent Cellular Cytotoxicity. Consequently, multiple mechanisms of resistance have been proposed. We present here a comprehensive review of our current understanding of the mechanisms, both of Trastuzumab action and clinical resistance to Trastuzumab-based therapies. We also review newer strategies (based on ErbB2 receptor biology) that are being explored to overcome resistance to Trastuzumab therapy.
Collapse
Affiliation(s)
- Tameka A Bailey
- Eppley Institute for Research in Cancer and Allied Diseases, College of Medicine, University of Nebraska Medical Center, 985950 Nebraska Medical Center Omaha, NE, USA
| | | | | | | | | | | | | |
Collapse
|
111
|
Brantley-Sieders DM. Clinical relevance of Ephs and ephrins in cancer: lessons from breast, colorectal, and lung cancer profiling. Semin Cell Dev Biol 2011; 23:102-8. [PMID: 22040912 DOI: 10.1016/j.semcdb.2011.10.014] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Accepted: 10/17/2011] [Indexed: 01/04/2023]
Abstract
Pre-clinical studies provide compelling evidence that members of the Eph family of receptor tyrosine kinases and their ephrin ligands promote tumor growth, invasion and metastasis, and neovascularization. Tumor suppressive roles have also been reported for the receptors, and ligand-dependent versus ligand-independent signaling has emerged as one key mechanism underlying tumor suppressive function as opposed to oncogenic effects. Determining how these observations relate to clinical outcome is a crucial step for translating the biological and mechanistic data into new molecularly targeted therapies. Expression profiling in human patient samples bridges this gap and provides valuable clinical relevance to laboratory observations. In addition to analyses performed using privately assembled patient tumor samples, publically available microarray datasets and tissue microarrays linked to clinical data have emerged as tractable tools for addressing the clinical relevance of specific molecules and families of related molecules. This review summarizes the clinical relevance of specific Eph and ephrin molecules in human breast, colorectal, and lung cancers.
Collapse
Affiliation(s)
- Dana M Brantley-Sieders
- Department of Medicine, Vanderbilt University School of Medicine, A-4323 MCN, 1161 21st Avenue South, Nashville, TN 37232-2363, USA.
| |
Collapse
|
112
|
Quesnelle KM, Grandis JR. Dual kinase inhibition of EGFR and HER2 overcomes resistance to cetuximab in a novel in vivo model of acquired cetuximab resistance. Clin Cancer Res 2011; 17:5935-44. [PMID: 21791633 DOI: 10.1158/1078-0432.ccr-11-0370] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
PURPOSE Acquired resistance to cetuximab, a chimeric epidermal growth factor receptor (EGFR)-targeting monoclonal antibody, is a widespread problem in the treatment of solid tumors. The paucity of preclinical models has limited investigations to determine the mechanism of acquired therapeutic resistance, thereby limiting the development of effective treatments. The purpose of this study was to generate cetuximab-resistant tumors in vivo to characterize mechanisms of acquired resistance. EXPERIMENTAL DESIGN We generated cetuximab-resistant clones from a cetuximab-sensitive bladder cancer cell line in vivo by exposing cetuximab-sensitive xenografts to increasing concentrations of cetuximab, followed by validation of the resistant phenotype in vivo and in vitro using invasion assays. A candidate-based approach was used to examine the role of HER2 on mediating cetuximab resistance both in vitro and in vivo. RESULTS We generated a novel model of cetuximab resistance, and, for the first time in the context of EGFR-inhibitor resistance, we identified increased phosphorylation of a C-terminal fragment of HER2 (611-CTF) in cetuximab-resistant cells. Afatinib (BIBW-2992), an irreversible kinase inhibitor targeting EGFR and HER2, successfully inhibited growth of the cetuximab-resistant cells in vitro. When afatinib was combined with cetuximab in vivo, we observed an additive growth inhibitory effect in cetuximab-resistant xenografts. CONCLUSIONS These data suggest that the use of dual EGFR-HER2 kinase inhibitors can enhance responses to cetuximab, perhaps in part due to downregulation of 611-CTF. This study conducted in a novel in vivo model provides a mechanistic rationale for ongoing phase I clinical trials using this combination treatment modality.
Collapse
Affiliation(s)
- Kelly M Quesnelle
- Department of Pharmacology & Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | | |
Collapse
|
113
|
Trastuzumab and lapatinib modulation of HER2 tyrosine/threonine phosphorylation and cell signaling. Med Oncol 2011; 29:1486-94. [DOI: 10.1007/s12032-011-0025-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2011] [Accepted: 06/30/2011] [Indexed: 01/26/2023]
|
114
|
Zagozdzon R, Gallagher WM, Crown J. Truncated HER2: implications for HER2-targeted therapeutics. Drug Discov Today 2011; 16:810-6. [PMID: 21704182 DOI: 10.1016/j.drudis.2011.06.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 05/05/2011] [Accepted: 06/06/2011] [Indexed: 11/15/2022]
Abstract
The HER2 receptor is currently one of the flagship therapeutic targets in clinical oncology. Trastuzumab, an antibody targeting HER2, has become a foundation of care in women with HER2-positive breast cancer. However, many women with metastatic breast cancer do not respond to trastuzumab-based therapy. One possible source of trastuzumab resistance is the presence of truncated forms of HER2 in the tumor. Numerous studies suggest that detection of truncated HER2 in the tumor should result in modification of the classical therapeutic approach. Recent development of several promising compounds brings hope that a generation of novel therapeutic modalities against HER2-positive cancers will be delivered in the future.
Collapse
Affiliation(s)
- Radoslaw Zagozdzon
- Cancer Biology and Therapeutics Group, UCD Conway Institute, UCD School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland.
| | | | | |
Collapse
|
115
|
Xia W, Liu Z, Zong R, Liu L, Zhao S, Bacus SS, Mao Y, He J, Wulfkuhle JD, Petricoin EF, Osada T, Yang XY, Hartman ZC, Clay TM, Blackwell KL, Lyerly HK, Spector NL. Truncated ErbB2 expressed in tumor cell nuclei contributes to acquired therapeutic resistance to ErbB2 kinase inhibitors. Mol Cancer Ther 2011; 10:1367-74. [PMID: 21673090 DOI: 10.1158/1535-7163.mct-10-0991] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
ErbB2 tyrosine kinase inhibitors (TKI) block tyrosine autophosphorylation and activation of the full-length transmembrane ErbB2 receptor (p185(ErbB2)). In addition to p185(ErbB2), truncated forms of ErbB2 exist in breast cancer cell lines and clinical tumors. The contribution of these truncated forms, specifically those expressed in tumor cell nuclei, to the development of therapeutic resistance to ErbB2 TKIs has not been previously shown. Here, we show that expression of a 95-kDa tyrosine phosphorylated form of ErbB2, herein referred to as p95L (lapatinib-induced p95) was increased in ErbB2(+) breast cancer cells treated with potent ErbB2 TKIs (lapatinib, GW2974). Expressed in tumor cell nuclei, tyrosine phosphorylation of p95L was resistant to inhibition by ErbB2 TKIs. Furthermore, the expression of p95L was increased in ErbB2(+) breast cancer models of acquired therapeutic resistance to lapatinib that mimic the clinical setting. Pretreatment with proteasome inhibitors blocked p95L induction in response to ErbB2 TKIs, implicating the role of the proteasome in the regulation of p95L expression. In addition, tyrosine phosphorylated C-terminal fragments of ErbB2, generated by alternate initiation of translation and similar in molecular weight to p95L, were expressed in tumor cell nuclei, where they too were resistant to inhibition by ErbB2 TKIs. When expressed in the nuclei of lapatinib-sensitive ErbB2(+) breast cancer cells, truncated ErbB2 rendered cells resistant to lapatinib-induced apoptosis. Elucidating the function of nuclear, truncated forms of ErbB2, and developing therapeutic strategies to block their expression and/or activation may enhance the clinical efficacy of ErbB2 TKIs.
Collapse
Affiliation(s)
- Wenle Xia
- Duke Comprehensive Cancer Research Center, Department of Medicine, Duke University School of Medicine, Durham, NC 27710, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
116
|
Marchini C, Gabrielli F, Iezzi M, Zenobi S, Montani M, Pietrella L, Kalogris C, Rossini A, Ciravolo V, Castagnoli L, Tagliabue E, Pupa SM, Musiani P, Monaci P, Menard S, Amici A. The human splice variant Δ16HER2 induces rapid tumor onset in a reporter transgenic mouse. PLoS One 2011; 6:e18727. [PMID: 21559085 PMCID: PMC3084693 DOI: 10.1371/journal.pone.0018727] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Accepted: 03/16/2011] [Indexed: 11/18/2022] Open
Abstract
Several transgenic mice models solidly support the hypothesis that HER2 (ERBB2) overexpression or mutation promotes tumorigenesis. Recently, a HER2 splice variant lacking exon-16 (Δ16HER2) has been detected in human breast carcinomas. This alternative protein, a normal byproduct of HER2, has an increased transforming potency compared to wild-type (wt) HER2 receptors. To examine the ability of Δ16HER2 to transform mammary epithelium in vivo and to monitor Δ16HER2-driven tumorigenesis in live mice, we generated and characterized a mouse line that transgenically expresses both human Δ16HER2 and firefly luciferase under the transcriptional control of the MMTV promoter. All the transgenic females developed multifocal mammary tumors with a rapid onset and an average latency of 15.11 weeks. Immunohistochemical analysis revealed the concurrent expression of luciferase and the human Δ16HER2 oncogene only in the mammary gland and in strict correlation with tumor development. Transgenic Δ16HER2 expressed on the tumor cell plasma membrane from spontaneous mammary adenocarcinomas formed constitutively active homodimers able to activate the oncogenic signal transduction pathway mediated through Src kinase. These new transgenic animals demonstrate the ability of the human Δ16HER2 isoform to transform "per se" mammary epithelium in vivo. The high tumor incidence as well as the short latency strongly suggests that the Δ16HER2 splice variant represents the transforming form of the HER2 oncoprotein.
Collapse
Affiliation(s)
- Cristina Marchini
- Department of Bioscience and Biotechnology, University of Camerino, Camerino, Italy
| | - Federico Gabrielli
- Department of Bioscience and Biotechnology, University of Camerino, Camerino, Italy
| | - Manuela Iezzi
- Aging Research Centre, G. d'Annunzio University, Chieti, Italy
| | - Santa Zenobi
- Department of Bioscience and Biotechnology, University of Camerino, Camerino, Italy
| | - Maura Montani
- Department of Bioscience and Biotechnology, University of Camerino, Camerino, Italy
| | - Lucia Pietrella
- Department of Bioscience and Biotechnology, University of Camerino, Camerino, Italy
| | - Cristina Kalogris
- Department of Bioscience and Biotechnology, University of Camerino, Camerino, Italy
| | - Anna Rossini
- Molecular Targeting Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS, Istituto Nazionale dei Tumori, AmadeoLab, Milan, Italy
| | - Valentina Ciravolo
- Molecular Targeting Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS, Istituto Nazionale dei Tumori, AmadeoLab, Milan, Italy
| | - Lorenzo Castagnoli
- Molecular Targeting Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS, Istituto Nazionale dei Tumori, AmadeoLab, Milan, Italy
| | - Elda Tagliabue
- Molecular Targeting Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS, Istituto Nazionale dei Tumori, AmadeoLab, Milan, Italy
| | - Serenella M. Pupa
- Molecular Targeting Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS, Istituto Nazionale dei Tumori, AmadeoLab, Milan, Italy
| | - Piero Musiani
- Aging Research Centre, G. d'Annunzio University, Chieti, Italy
| | - Paolo Monaci
- Department of Bioscience and Biotechnology, University of Camerino, Camerino, Italy
| | - Sylvie Menard
- Molecular Targeting Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS, Istituto Nazionale dei Tumori, AmadeoLab, Milan, Italy
| | - Augusto Amici
- Department of Bioscience and Biotechnology, University of Camerino, Camerino, Italy
- * E-mail:
| |
Collapse
|
117
|
Abstract
A subtype of HER2-positive tumors with distinct biological and clinical features expresses a series of carboxy-terminal fragments collectively known as p95HER2. One of these fragments, named 100- to 115-kDa p95HER2 or 611-CTF, is hyperactive because of its ability to form homodimers maintained by intermolecular disulfide bonds. Despite lacking the majority of the extracellular domain, this HER2 fragment drives breast cancer progression in vivo. The recent availability of specific anti-p95 antibodies has confirmed previous results indicating that the expression of p95HER2 is predictive of poor prognosis and correlates with resistance to the treatment with trastuzumab, a therapeutic antibody directed against the extracellular domain of HER2.
Collapse
Affiliation(s)
- Joaquín Arribas
- Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain.
| | | | | | | |
Collapse
|
118
|
Bates M, Sperinde J, Köstler WJ, Ali SM, Leitzel K, Fuchs EM, Paquet A, Lie Y, Sherwood T, Horvat R, Singer CF, Winslow J, Weidler JM, Huang W, Lipton A. Identification of a subpopulation of metastatic breast cancer patients with very high HER2 expression levels and possible resistance to trastuzumab. Ann Oncol 2011; 22:2014-2020. [PMID: 21289364 DOI: 10.1093/annonc/mdq706] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Patients with metastatic breast cancer (MBC) overexpressing HER2 (human epidermal growth factor receptor 2) are currently selected for treatment with trastuzumab, but not all patients respond. PATIENTS AND METHODS Using a novel assay, HER2 protein expression (H2T) was measured in formalin-fixed, paraffin-embedded primary breast tumors from 98 women treated with trastuzumab-based therapy for MBC. Using subpopulation treatment effect pattern plots, the population was divided into H2T low (H2T < 13.8), H2T high (H2T ≥ 68.5), and H2T intermediate (13.8 ≤ H2T < 68.5) subgroups. Kaplan-Meier (KM) analyses were carried out comparing the groups for time to progression (TTP) and overall survival (OS). Cox multivariate analyses were carried out to identify correlates of clinical outcome. Bootstrapping analyses were carried out to test the robustness of the results. RESULTS TTP improved with increasing H2T until, at the highest levels of H2T, an abrupt decrease in the TTP was observed. KM analyses demonstrated that patients with H2T low tumors [median TTP 4.2 months, hazard ratio (HR) = 3.7, P < 0.0001] or H2T high tumors (median TTP 4.6 months, HR = 2.7, P = 0.008) had significantly shorter TTP than patients whose tumors were H2T intermediate (median TTP 12 months). OS analyses yielded similar results. CONCLUSIONS MBC patients with very high levels of H2T may represent a subgroup with de novo resistance to trastuzumab. These results are preliminary and require confirmation in larger controlled clinical cohorts.
Collapse
Affiliation(s)
- M Bates
- Division of Clinical Research.
| | - J Sperinde
- Division of Research and Development, Monogram Biosciences, South San Francisco, USA
| | - W J Köstler
- Clinical Division of Oncology, Department of Medicine I, Medical University of Vienna, Vienna, Austria
| | - S M Ali
- Department of Medicine, Lebanon Veterans Affairs Medical Center, Lebanon
| | - K Leitzel
- Department of Medicine, Division of Hematology/Medical Oncology, Penn State Hershey Medical Center, Hershey
| | - E M Fuchs
- Clinical Division of Oncology, Department of Medicine I, Medical University of Vienna, Vienna, Austria
| | - A Paquet
- Department of Translational Medicine and Biomarker Development, Division of Biostatics and Bioinformatics, Monogram Biosciences, South San Francisco, USA
| | - Y Lie
- Division of Clinical Research
| | | | - R Horvat
- Departments of Clinical Pathology
| | - C F Singer
- Obstetrics and Gynecology, Medical University of Vienna, Vienna, Austria
| | - J Winslow
- Division of Research and Development, Monogram Biosciences, South San Francisco, USA
| | | | - W Huang
- Division of Clinical Research
| | - A Lipton
- Department of Medicine, Division of Hematology/Medical Oncology, Penn State Hershey Medical Center, Hershey
| |
Collapse
|
119
|
Abstract
The activity of a variety of extracellular signaling factors is tightly regulated by proteins containing A Disintegrin And a Metalloprotease domain (ADAM) metalloproteases through limited proteolysis. Thus, the identification of ADAM substrates may unveil novel components and mechanisms of cell signaling pathways. We report the identification of the transmembrane protein vasorin (VASN), a transforming growth factor-β (TGFβ) trap, as a substrate of ADAM17. The metalloprotease efficiently generates a soluble fragment encompassing the extracellular domain of VASN. Despite the importance of TGFβ in normal development and tumor progression, the regulation of VASN is completely unknown. Here, we show that only the soluble form of VASN inhibits TGFβ and that the secretion of VASN is tightly controlled by ADAM17. Hence, inhibition of ADAM17 leads to the upregulation of TGFβ signaling. Adding a new level of complexity to the function of ADAM17, we finally show that, through the cleavage of VASN, the metalloprotease controls TGFβ-mediated epithelial-to-mesenchymal transition.
Collapse
|
120
|
Traditional molecular markers and response to adjuvant endocrine or trastuzumab-based therapies. Curr Opin Oncol 2010; 22:541-6. [PMID: 20827197 DOI: 10.1097/cco.0b013e32833f4882] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
PURPOSE OF REVIEW The accurate assessment of traditional molecular markers is essential to inform the choice of the adjuvant systemic treatments for patients with breast cancer. Extensive research efforts have been made to explore whether it is also possible to predict the actual response to the different therapeutic options based on the expression of these markers. RECENT FINDINGS Endocrine responsiveness of breast cancer has been eventually defined according to the expression of estrogen receptors in at least 1% of invasive tumor cells. The quantitative evaluation of estrogen receptors, progesterone receptors (PgR) and Ki-67 labeling index may help in selecting patients with estrogen receptor-positive and HER2-negative tumors who can be spared or may benefit from the addition of chemotherapy to endocrine therapy. Guideline recommendations for an optimal testing of estrogen receptors and PgR have been issued to assist pathologists in the accurate assessment of these markers. Progress has also been made in the identification of candidate patients to HER2-targeted therapies and in the prediction of response to trastuzumab. SUMMARY Traditional molecular markers play a major role in the selection of candidate patients to systemic interventions, but they are of limited value in predicting their actual response to the different treatments, especially when the markers are evaluated individually.
Collapse
|
121
|
Abstract
Trastuzumab is the first Food and Drug Administration (FDA)-approved therapeutic targeting a HER-family receptor tyrosine kinase (HER2/ErbB2/neu). Although trastuzumab is effective in the treatment of HER2-positive breast cancer, a substantial proportion of patients will not respond to trastuzumab-based regimens (primary resistance), and those who do respond will often lose clinical benefits (i.e., secondary resistance). Although multiple mechanisms underlying the development of secondary trastuzumab resistance have been identified, few studies have specifically examined the basis of primary trastuzumab resistance. Here, we review these studies, which together demonstrate that trastuzumab induces phenotypic changes in tumor cells, even when they are not growth inhibited by trastuzumab, including changes in gene expression. These changes have important clinical implications, including the sensitization of malignant cells to other therapeutic drugs. In light of these observations, we propose that the conventional definition of resistance as it pertains to trastuzumab and, perhaps, to other targeted therapeutics, may require revision. The results of these studies will be useful in informing the direction of future basic and clinical research focused on overcoming primary trastuzumab resistance.
Collapse
Affiliation(s)
- Jason A Wilken
- Yale University, School of Medicine, Department of Obstetrics, Gynecology, and Reproductive Sciences, New Haven, Connecticut, USA
| | | |
Collapse
|
122
|
Parra-Palau JL, Pedersen K, Peg V, Scaltriti M, Angelini PD, Escorihuela M, Mancilla S, Sánchez Pla A, Ramón Y Cajal S, Baselga J, Arribas J. A major role of p95/611-CTF, a carboxy-terminal fragment of HER2, in the down-modulation of the estrogen receptor in HER2-positive breast cancers. Cancer Res 2010; 70:8537-46. [PMID: 20978202 DOI: 10.1158/0008-5472.can-10-1701] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Current classification of breast cancers depends in great part on the expression of human epidermal growth factor receptor 2 (HER2), a cell surface tyrosine kinase receptor, and estrogen receptor (ER), the nuclear receptor for estrogen. In addition to reliable biomarkers, these receptors are targets of effective and widely used antitumor drugs. During malignant progression, HER2 and ER can establish an intricate cross-talk. In some cases, HER2 overexpression leads to the downregulation of ER and undermining of anti-ER therapies. A subgroup of HER2-positive breast cancer patients with poor prognosis expresses a heterogeneous collection of HER2 carboxy-terminal fragments (CTF) collectively known as p95HER2. One of these fragments, 611-CTF, is oncogenic in a variety of preclinical models. However, because of the lack of an appropriate tool to specifically analyze its levels in the clinical setting, the value of 611-CTF as a biomarker has not been established yet. Here, we show that 611-CTF induces resistance to antiestrogen therapy and a more pronounced down-modulation of ER than that induced by full-length HER2. To validate this effect in breast cancer samples, we developed specific anti-611-CTF antibodies. With these antibodies, we showed that, whereas the frequency of ER positivity in HER2-positive/611-CTF-negative tumors (72.6%) is similar to that reported for HER2-negative tumors (70-80%), the number of ER-positive tumors in the 611-CTF-positive subgroup is very low (31.2%). These results reveal a mechanism of ER regulation mediated by HER2, which suggests a new strategy to improve responses to endocrine therapy in breast cancer.
Collapse
Affiliation(s)
- Josep Lluís Parra-Palau
- Statistics Department, Faculty of Biology, Vall d'Hebron Institute of Oncology, University of Barcelona, Barcelona, Spain
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
123
|
Arribas J, Parra-Palau JL, Pedersen K. HER2 fragmentation and breast cancer stratification. Clin Cancer Res 2010; 16:4071-3. [PMID: 20682714 DOI: 10.1158/1078-0432.ccr-10-1501] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
HER2 is a tyrosine kinase receptor whose overexpression in breast cancers correlates with poor prognosis. A subset of HER2-positive tumors also expresses a series of HER2 fragments, collectively known as p95HER2. These fragments are emerging as a valuable biomarker for this subset of patients, who have a particularly poor prognosis.
Collapse
|
124
|
Sperinde J, Jin X, Banerjee J, Penuel E, Saha A, Diedrich G, Huang W, Leitzel K, Weidler J, Ali SM, Fuchs EM, Singer CF, Köstler WJ, Bates M, Parry G, Winslow J, Lipton A. Quantitation of p95HER2 in Paraffin Sections by Using a p95-Specific Antibody and Correlation with Outcome in a Cohort of Trastuzumab-Treated Breast Cancer Patients. Clin Cancer Res 2010; 16:4226-35. [DOI: 10.1158/1078-0432.ccr-10-0410] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
125
|
Ingalla EQ, Miller JK, Wald JH, Workman HC, Kaur RP, Yen L, Fry WHD, Borowsky AD, Young LJT, Sweeney C, Carraway KL. Post-transcriptional mechanisms contribute to the suppression of the ErbB3 negative regulator protein Nrdp1 in mammary tumors. J Biol Chem 2010; 285:28691-7. [PMID: 20628057 DOI: 10.1074/jbc.m110.127977] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The ErbB2 and ErbB3 receptor tyrosine kinases act synergistically to promote cellular properties associated with tumor development. Previous studies indicate that endogenous ErbB3 protein is markedly elevated in mouse mammary tumors induced by transgenic ErbB2 overexpression. However, this occurs in the absence of elevated ErbB3 transcript, indicating that post-transcriptional regulatory mechanisms play crucial roles in suppressing ErbB3 protein in normal tissue. Our previous studies also demonstrate that protein levels of Nrdp1, an E3 ubiquitin ligase that targets ErbB3 for degradation, are markedly suppressed in tumors from ErbB2 transgenic animals relative to normal tissue. Here we demonstrate that transgenic expression of Nrdp1 cDNA in the mouse mammary gland is not sufficient to suppress elevated ErbB3 levels or tumor initiation and growth in ErbB2 transgenic mice. Unexpectedly, Nrdp1 protein is absent in tumors from Nrdp1/ErbB2 bigenic mice, and real time PCR analysis indicates that Nrdp1 protein levels are suppressed post-transcriptionally. Nrdp1 protein is more resistant to proteasome-dependent degradation when exogenously expressed in cultured MCF10A nontransformed human breast epithelial cells than in breast tumor cells. These observations indicate that mammary tumors use potent post-transcriptional mechanisms to suppress Nrdp1 protein levels and that protein destabilization may play a central role in Nrdp1 loss in tumors.
Collapse
Affiliation(s)
- Ellen Q Ingalla
- University of California Davis Cancer Center, Sacramento, California 95817, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
126
|
Ghedini GC, Ciravolo V, Tortoreto M, Giuffrè S, Bianchi F, Campiglio M, Mortarino M, Figini M, Coliva A, Carcangiu ML, Zambetti M, Piazza T, Ferrini S, Ménard S, Tagliabue E, Pupa SM. Shed HER2 extracellular domain in HER2-mediated tumor growth and in trastuzumab susceptibility. J Cell Physiol 2010; 225:256-65. [DOI: 10.1002/jcp.22257] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
|
127
|
Scaltriti M, Chandarlapaty S, Prudkin L, Aura C, Jimenez J, Angelini PD, Sánchez G, Guzman M, Parra JL, Ellis C, Gagnon R, Koehler M, Gomez H, Geyer C, Cameron D, Arribas J, Rosen N, Baselga J. Clinical benefit of lapatinib-based therapy in patients with human epidermal growth factor receptor 2-positive breast tumors coexpressing the truncated p95HER2 receptor. Clin Cancer Res 2010; 16:2688-95. [PMID: 20406840 DOI: 10.1158/1078-0432.ccr-09-3407] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE A subgroup of human epidermal growth factor receptor 2 (HER2)-overexpressing breast tumors coexpresses p95HER2, a truncated HER2 receptor that retains a highly functional HER2 kinase domain but lacks the extracellular domain and results in intrinsic trastuzumab resistance. We hypothesized that lapatinib, a HER2 tyrosine kinase inhibitor, would be active in these tumors. We have studied the correlation between p95HER2 expression and response to lapatinib, both in preclinical models and in the clinical setting. EXPERIMENTAL DESIGN Two different p95HER2 animal models were used for preclinical studies. Expression of p95HER2 was analyzed in HER2-overexpressing breast primary tumors from a first-line lapatinib monotherapy study (EGF20009) and a second-line lapatinib in combination with capecitabine study (EGF100151). p95HER2 expression was correlated with overall response rate (complete + partial response), clinical benefit rate (complete response + partial response + stable disease > or =24 wk), and progression-free survival using logistic regression and Cox proportional hazard models. RESULTS Lapatinib inhibited tumor growth and the HER2 downstream signaling of p95HER2-expressing tumors. A total of 68 and 156 tumors from studies EGF20009 and EGF100151 were evaluable, respectively, for p95HER2 detection. The percentage of p95HER2-positive patients was 20.5% in the EGF20009 study and 28.5% in the EGF100151 study. In both studies, there was no statistically significant difference in progression-free survival, clinical benefit rate, and overall response rate between p95HER2-positive and p95HER2-negative tumors. CONCLUSIONS Lapatinib as a monotherapy or in combination with capecitabine seems to be equally effective in patients with p95HER2-positive and p95HER2-negative HER2-positive breast tumors.
Collapse
Affiliation(s)
- Maurizio Scaltriti
- Department of Medical Oncology, Vall d'Hebron University Hospital, Barcelona, Spain
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
128
|
Tagliabue E, Balsari A, Campiglio M, Pupa SM. HER2 as a target for breast cancer therapy. Expert Opin Biol Ther 2010; 10:711-24. [DOI: 10.1517/14712591003689972] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
129
|
Gullick WJ. The epidermal growth factor system of ligands and receptors in cancer. Eur J Cancer 2010; 45 Suppl 1:205-10. [PMID: 19775619 DOI: 10.1016/s0959-8049(09)70035-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
|
130
|
Christoffersen T, Guren TK, Spindler KLG, Dahl O, Lønning PE, Gjertsen BT. Cancer therapy targeted at cellular signal transduction mechanisms: Strategies, clinical results, and unresolved issues. Eur J Pharmacol 2009; 625:6-22. [DOI: 10.1016/j.ejphar.2009.10.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 09/30/2009] [Accepted: 10/08/2009] [Indexed: 12/19/2022]
|
131
|
Inhibitors of HSP90 block p95-HER2 signaling in Trastuzumab-resistant tumors and suppress their growth. Oncogene 2009; 29:325-34. [PMID: 19855434 PMCID: PMC3057066 DOI: 10.1038/onc.2009.337] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The anti-HER2 antibody Trastuzumab (Herceptin) has been proven to be effective in the treatment of HER2 overexpressing breast cancer; resistance, however invariably emerges in metastatic tumors. The expression of p95-HER2, a form of HER2 with a truncated extracellular domain that lacks the Trastuzumab binding epitope, has been implicated as a mechanism of resistance to the antibody. We utilized an in vivo tumor model that overexpresses p95-HER2 and demonstrate it to be resistant to the signaling and antitumor effects of Trastuzumab. We find that both full length and p95-HER2 interact with the HSP90 chaperone protein and are degraded in tumor cells exposed to HSP90 inhibitors in tissue culture and in vivo. Loss of expression of p95-HER2 is accompanied by downregulation of the PI3K/AKT and ERK signaling pathways and inhibition of cell proliferation. Chronic administration of HSP90 inhibitors in vivo results in sustained loss of HER2 and p95-HER2 expression and inhibition of AKT activation together with induction of apoptosis and complete inhibition of tumor growth in Trastuzumab-resistant, p95-HER2-overexpressing models. Thus, p95-HER2 is an HSP90 client protein, the expression and function of which can be effectively suppressed in vivo by HSP90 inhibitors. HSP90 inhibition is therefore a potentially effective therapeutic strategy for p95-HER2-mediated Trastuzumab-resistant breast cancer.
Collapse
|
132
|
García-Castillo J, Pedersen K, Angelini PD, Bech-Serra JJ, Colomé N, Cunningham MP, Parra-Palau JL, Canals F, Baselga J, Arribas J. HER2 carboxyl-terminal fragments regulate cell migration and cortactin phosphorylation. J Biol Chem 2009; 284:25302-13. [PMID: 19589785 DOI: 10.1074/jbc.m109.001982] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A group of breast cancer patients with a higher probability of developing metastasis expresses a series of carboxyl-terminal fragments (CTFs) of the tyrosine kinase receptor HER2. One of these fragments, 611-CTF, is a hyperactive form of HER2 that constitutively establishes homodimers maintained by disulfide bonds, making it an excellent model to study overactivation of HER2 during tumor progression and metastasis. Here we show that expression of 611-CTF increases cell motility in a variety of assays. Since cell motility is frequently regulated by phosphorylation/dephosphorylation, we looked for phosphoproteins mediating the effect of 611-CTF using two alternative proteomic approaches, stable isotope labeling with amino acids in cell culture and difference gel electrophoresis, and found that the latter is particularly well suited to detect changes in multiphosphorylated proteins. The difference gel electrophoresis screening identified cortactin, a cytoskeleton-binding protein involved in the regulation of cell migration, as a phosphoprotein probably regulated by 611-CTF. This result was validated by characterizing cortactin in cells expressing this HER2 fragment. Finally, we showed that the knockdown of cortactin impairs 611-CTF-induced cell migration. These results suggest that cortactin is a target of 611-CTF involved in the regulation of cell migration and, thus, in the metastatic behavior of breast tumors expressing this CTF.
Collapse
Affiliation(s)
- Jesús García-Castillo
- Medical Oncology Research Program, Vall d'Hebron University Hospital, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain
| | | | | | | | | | | | | | | | | | | |
Collapse
|
133
|
Abstract
Aberrant receptor expression or functioning of the epidermal growth factor receptor (Erbb) family plays a crucial part in the development and evolution of cancer. Inhibiting the signalling activity of individual receptors in this family has advanced the treatment of a range of human cancers. In this Review we re-evaluate the role of two important family members, ERBB2 (also known as HER2) and ERBB3 (also known as HER3), and explore the mechanisms of action and preclinical and clinical data for new therapies that target signalling through these pivotal receptors. These new therapies include tyrosine kinase inhibitors, antibody-chemotherapy conjugates, heat-shock protein inhibitors and antibodies that interfere with the formation of ERBB2-ERBB3 dimers.
Collapse
Affiliation(s)
- José Baselga
- Vall d'Hebron Institute of Oncology, Vall d'Hebron University Hospital, Passeig Vall d'Hebron 119-129, Barcelona 08035, Spain.
| | | |
Collapse
|