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Gefitinib Induces Epidermal Growth Factor Receptor Dimers Which Alters the Interaction Characteristics with (125)I-EGF
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science, Biomedical Radiation Sciences.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science, Biomedical Radiation Sciences.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science, Biomedical Radiation Sciences.
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2011 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 6, no 9, e24739- p.Article in journal (Refereed) Published
Abstract [en]

The tyrosine kinase inhibitor gefitinib inhibits growth in some tumor types by targeting the epidermal growth factor receptor (EGFR). Previous studies show that the affinity of the EGF-EGFR interaction varies between hosting cell line, and that gefitinib increases the affinity for some cell lines. In this paper, we investigate possible mechanisms behind these observations. Real-time interaction analysis in LigandTracer (R) Grey revealed that the HER2 dimerization preventing antibody pertuzumab clearly modified the binding of (125)I-EGF to EGFR on HER2 overexpressing SKOV3 cells in the presence of gefitinib. Pertuzumab did not affect the binding on A431 cells, which express low levels of HER2. Cross-linking measurements showed that gefitinib increased the amount of EGFR dimers 3.0-3.8 times in A431 cells in the absence of EGF. In EGF stimulated SKOV3 cells the amount of EGFR dimers increased 1.8-2.2 times by gefitinib, but this effect was cancelled by pertuzumab. Gefitinib treatment did not alter the number of EGFR or HER2 expressed in tumor cell lines A431, U343, SKOV3 and SKBR3. Real-time binding traces were further analyzed in a novel tool, Interaction Map, which deciphered the different components of the measured interaction and supports EGF binding to multiple binding sites. EGFR and HER2 expression affect the levels of EGFR monomers, homodimers and heterodimers and EGF binds to the various monomeric/dimeric forms of EGFR with unique binding properties. Taken together, we conclude that dimerization explains the varying affinity of EGF - EGFR in different cells, and we propose that gefitinib induces EGFR dimmers, which alters the interaction characteristics with (125)I-EGF.

Place, publisher, year, edition, pages
2011. Vol. 6, no 9, e24739- p.
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:uu:diva-159470DOI: 10.1371/journal.pone.0024739ISI: 000294803200045OAI: oai:DiVA.org:uu-159470DiVA: diva2:445498
Available from: 2011-10-04 Created: 2011-10-03 Last updated: 2017-12-08Bibliographically approved
In thesis
1. Novel Methods for Analysis of Heterogeneous Protein-Cell Interactions: Resolving How the Epidermal Growth Factor Binds to Its Receptor
Open this publication in new window or tab >>Novel Methods for Analysis of Heterogeneous Protein-Cell Interactions: Resolving How the Epidermal Growth Factor Binds to Its Receptor
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Cells are complex biological units with advanced signalling systems, a dynamic capacity to adapt to its environment, and the ability to divide and grow. In fact, they are of such high level of complexity that it has deemed extremely difficult or even impossible to completely understand cells as complete units. The search for comprehending the cell has instead been divided into small, relatively isolated research fields, in which simplified models are used to explain cell biology. The result produced through these reductionistic investigations is integral for our current description of biology. However, there comes a time when it is possible to go beyond such simplifications and investigate cell biology at a higher level of complexity. That time is now.

This thesis describes the development of mathematical tools to investigate intricate biological systems, with focus on heterogeneous protein interactions. By the use of simulations, real-time measurements and kinetic fits, standard assays for specificity measurements and receptor quantification were scrutinized in order to find optimal experimental settings and reduce labour time as well as reagent cost. A novel analysis platform, called Interaction Map, was characterized and applied on several types of interactions. Interaction Map decomposes a time-resolved binding curve and presents information on the kinetics and magnitude of each interaction that contributed to the curve. This provides a greater understanding of parallel interactions involved in the same biological system, such as a cell. The heterogeneity of the epidermal growth factor receptor (EGFR) system was investigated with Interaction Map applied on data from the instrument LigandTracer, together with complementing manual assays. By further introducing disturbances to the system, such as tyrosine kinase inhibitors and variation in temperature, information was obtained about dimerization, internalization and degradation rates.

In the long term, analysis of binding kinetics and combinations of parallel interactions can improve the understanding of complex biomolecular mechanisms in cells and may explain some of the differences observed between cell lines, medical treatments and groups of patients.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. 65 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 854
Keyword
Heterogeneity, Kinetics, EGFR, HER2, LigandTracer, Interaction Map, Internalization, Specificity
National Category
Medical Biotechnology Cell and Molecular Biology
Research subject
Medical Science
Identifiers
urn:nbn:se:uu:diva-183872 (URN)978-91-554-8570-2 (ISBN)
Public defence
2013-02-15, Rudbeck Hall, Rudbeck Laboratory, Dag Hammarskjöldsväg 20, Uppsala, 09:15 (English)
Opponent
Supervisors
Available from: 2013-01-24 Created: 2012-11-05 Last updated: 2013-02-11Bibliographically approved

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