A Unique Structure for Epidermal Growth Factor Receptor Bound to GW572016 (Lapatinib) Relationships among Protein Conformation, Inhibitor Off-Rate, and Receptor Activity in Tumor Cells

Department of Computational, Analytical and Structural Sciences, GlaxoSmithKline, Inc., Research Triangle Park, North Carolina 27709, USA.
Cancer Research (Impact Factor: 9.33). 10/2004; 64(18):6652-9. DOI: 10.1158/0008-5472.CAN-04-1168
Source: PubMed

ABSTRACT GW572016 (Lapatinib) is a tyrosine kinase inhibitor in clinical development for cancer that is a potent dual inhibitor of epidermal growth factor receptor (EGFR, ErbB-1) and ErbB-2. We determined the crystal structure of EGFR bound to GW572016. The compound is bound to an inactive-like conformation of EGFR that is very different from the active-like structure bound by the selective EGFR inhibitor OSI-774 (Tarceva) described previously. Surprisingly, we found that GW572016 has a very slow off-rate from the purified intracellular domains of EGFR and ErbB-2 compared with OSI-774 and another EGFR selective inhibitor, ZD-1839 (Iressa). Treatment of tumor cells with these inhibitors results in down-regulation of receptor tyrosine phosphorylation. We evaluated the duration of the drug effect after washing away free compound and found that the rate of recovery of receptor phosphorylation in the tumor cells reflected the inhibitor off-rate from the purified intracellular domain. The slow off-rate of GW572016 correlates with a prolonged down-regulation of receptor tyrosine phosphorylation in tumor cells. The differences in the off-rates of these drugs and the ability of GW572016 to inhibit ErbB-2 can be explained by the enzyme-inhibitor structures.

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    • "Epidermal growth factor receptors are family of receptor tyrosine kinases that play a crucial rule in cell growth regulation and survival (Olayioye et al., 2000); they are highly expressed in a number of human tumors as breast cancer, colon, prostate and ovarian cancer, thus considered as attractive targets for the design and development of new anticancer active agents. It was also reported that quinazoline derivatives have a potent inhibitory activity against EGFR (Barlesi et al., 2005; Burris et al., 2005; Hennequin et al., 2002; Kopper, 2008; Wood et al., 2004); hence, docking the best active compounds 2c,d and 3a,f into ATP binding site of EGFR was performed to explore the possible interactions and amino acid binding for these compounds with EGFR. "
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    Medicinal Chemistry Research 03/2015; 24(7). DOI:10.1007/s00044-015-1357-1 · 1.40 Impact Factor
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    • "Inhibitors binding to the DFG-out and other inactive conformations may have several advantages over regular ATP-site inhibitors, including better selectivity and slower off-rates that increase the residence time of the inhibitor bound to the kinase (Wood et al., 2004; Tummino and Copeland, 2008). However, the paucity of available structures for the inactive, unliganded protein kinases (apo-form) represents a major hurdle in designing inhibitors targeting the inactive conformations. "
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    Pharmacological reviews 10/2014; 66(4):918-47. DOI:10.1124/pr.114.008862 · 17.10 Impact Factor
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    • "While kinase inhibitor drugs are supposed to act with same mechanisms, there are characteristic differences in on-off rates, receptor conformation and accessibilities of its serine/threonine/tyrosine target substrates [27]. Apparently, individual inhibitors use distinct mechanisms to achieve similar results: cell-cycle inhibitors are induced by Gefitinib, conversely cell-cycle promoters are suppressed by Erlotinib – the same results achieved by different routes. "
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    ABSTRACT: EGF and its receptor EGFR serve as a paradigm for signaling in cell, molecular and tumor biology. EGFR inhibitors, drugs targeting the intracellular kinase activity and antibodies targeting the extracellular ligand binding, are used to treat breast, lung, colon and other cancers. Nominally affecting the same target, inhibitors have different effects, suggesting that use of inhibitor combinations may provide beneficial in cancer treatment. To explore the specific and the common transcriptional effects of EGFR inhibitors, we present metaanalysis of 20 individual studies comprising 346 microarrays. We identified specific gene subsets regulated by kinase inhibitors, those regulated using antibodies and by suppressing EGFR expression using miR-7. Unreported before, the inhibitors prominently induce lysosome components. All inhibitors rely on related sets of transcription factors and protein kinases, both for transcriptional induction and suppression. However, we find that Gefitinib suppresses apoptosis inhibitors, while inducing cell-cycle inhibitors; conversely, Erlotinib suppresses cell-cycle and cell migration genes, while inducing proapoptotic genes. EGFR-targeting antibodies specifically suppress cell motility, developmental and differentiation processes, while inducing the contractile apparatus. miR-7, distinctively, suppresses cell-cycle genes, while inducing transcription machinery. These metaanalysis results suggest that different inhibitors have overlapping but quite distinct effects in target cells. Judicial use of EGFR-targeting combinations, i.e., simultaneous use of antibodies and multiple kinase inhibitors, may provide more effective cancer treatments with fewer side-effects and avoid development of resistance. We expect, moreover, that specific drug combination treatments can be fine-tuned to achieve specific, personalized results.
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