API

Event: 941

Key Event Title

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Short name

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Activation, EGFR

Biological Context

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Cell term

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Organ term

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Key Event Components

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Key Event Overview

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AOPs Including This Key Event

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Stressors

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Taxonomic Applicability

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Life Stages

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Sex Applicability

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Key Event Description

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The EGF receptor family comprises 4 members, EGFR (also referred to as ErbB1/HER1), ErbB2/Neu/HER2, ErbB3/HER3 and ErbB4/HER4, all of which are transmembrane glycoproteins with an extracellular ligand binding site and an intracellular tyrosine kinase domain. Receptor-ligand binding induces dimerization and internalization, subsequently leading to activation of the receptor through autophosphorylation (Higashiyama et al., 2008).

EGFR signaling is central to airway epithelial maintenance and mucin production (Burgel and Nadel, 2004), and EGFR expression has been demonstrated in lung epithelial cells under physiological (albeit weakly) as well as pathological conditions in vitro and in vivo (Aida et al., 1994; Burgel and Nadel, 2008; O’Donnell et al., 2004; Polosa et al., 1999). Of note, lung epithelial EGFR phosphorylation (i.e., activation) was increased under conditions of oxidative stress including exposure to H₂O₂ (Goldkorn et al., 1998), naphthalene (Van Winkle et al., 1997), cigarette smoke (de Boer et al., 2006; Marinaş et al., 2011) and in the presence of neutrophils or neutrophil elastase (Kohri et al., 2002; Shao et al., 2004; Shao and Nadel, 2005; Shim et al., 2001; Takeyama et al., 2000). EGFR activation by oxidative stress may have a number of root causes: ROS were shown to increase production of EGF, the prime EGFR ligand, by lung epithelial cells (Casalino-Matsuda et al., 2004). Similarly, expression and secretion of TGF-α and AREG, also EGFR ligands, were elevated in human bronchial epithelial cells in response to fine particulate matter (PM2.5), diesel particulate matter and cigarette smoke exposure (Blanchet et al., 2004; Lemjabbar et al., 2003; Rumelhard et al., 2007). Mechanistically, this process is dependent on ROS-mediated activation of metalloproteinases or ADAMs which cleave membrane-bound EGFR ligand precursors, making them locally available to bind to and transactivate EGFR in an autocrine manner (Deshmukh et al., 2009; Kim et al., 2004b; Val et al., 2012; Yoshisue and Hasegawa, 2004). Furthermore, ligand binding to EGFR itself was shown to lead to H₂O₂ production, thereby facilitating receptor activation and downstream signaling (DeYulia et al., 2005; DeYulia and Cárcamo, 2005; Truong and Carroll, 2012). While it is tempting to speculate that the increase in H₂O₂ would perpetuate EGFR activation via the continuous proteolytic shedding of pro-ligands in an autocrine loop, multiple lines of evidence suggest that oxidative modification, specifically EGFR sulfenylation, contributes to enhanced tyrosine phosphorylation of the receptor and downstream signaling (Paulsen et al., 2011; Ravid et al., 2002; Truong and Carroll, 2012; Truong et al., 2016).

Classical EGFR downstream signaling involves activation of Ras which subsequently initiates signal transduction through the Raf-1/MEK/ERK pathway. MAP kinase activation in turn promotes airway epithelial cell proliferation and differentiation (Hackel et al., 1999; Kim et al., 2005; Lemjabbar et al., 2003) and facilitates epithelial wound repair (Allahverdian et al., 2010; Burgel and Nadel, 2004; Van Winkle et al., 1997).

How It Is Measured or Detected

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Proof of EGFR activation can be derived from Western blots of e.g. untreated and treated cell or tissue lysates using specific antibodies targeting the phosphorylated EGFR epitopes. Densitometric evaluation of the colorimetrically stained, chemiluminescent or radioactive bands on the blot then permit a (semi-)quantitative measure of activation. Moreover, the addition of EGFR inhibitors such as AG1478 and BIBX 1522 or neutralizing antibodies is well suited to demonstrate causality.

Domain of Applicability

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EGFR activation in human, mouse and rat is well documented, and EGF ligands and EGFR are orthologous within these species. EGFR is a driver of human cancer in various tissues and numerous drugs are approved that inhibit EGFR activation (Ciardiello and Tortora, 2008). Although EGFR and its ligands are expressed in human, mouse and rat (Chen et al., 2007), species differences have been noted in binding and structure (Nexø and Hansen, 1985), and even can have opposite downstream effects in mouse and rat (Kiley and Chevalier, 2007).

Evidence for Perturbation by Stressor

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Overview for Molecular Initiating Event

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EGFR activation in lung epithelial cells can be triggered by exposure to H₂O₂ (Goldkorn et al., 1998; Takeyama et al., 2000), naphthalene (Van Winkle et al., 1997), cigarette smoke (Takeyama et al., 2001; de Boer et al., 2006; Marinaş et al., 2011; Yu et al., 2011; Yu et al., 2015), acrolein (Deshmukh et al., 2008), and TCDD (Lee et al., 2011). Mechanistically, this process is dependent on ROS-mediated activation of metalloproteinases or ADAMs which cleave membrane-bound EGFR ligand precursors, making them locally available to bind to and transactivate EGFR in an autocrine manner (Deshmukh et al., 2009; Kim et al., 2004b; Val et al., 2012; Yoshisue and Hasegawa, 2004). Furthermore, ligand binding to EGFR itself was shown to lead to H₂O₂ production, thereby facilitating receptor activation and downstream signaling (DeYulia et al., 2005; DeYulia and Cárcamo, 2005; Truong and Carroll, 2012).

References

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Aida, S., et al., Distribution of epidermal growth factor and epidermal growth factor receptor in human lung: immunohistochemical and immunoelectron-microscopic studies. Respiration, 1994. 61(3):161-166.

Allahverdian, S., et al., Sialyl Lewis X modification of the epidermal growth factor receptor regulates receptor function during airway epithelial wound repair. Clin Exp Allergy, 2010. 40(4):607-618.

Blanchet, S., et al., Fine particulate matter induces amphiregulin secretion by bronchial epithelial cells. Am J Resp Cell Mol Biol, 2004. 30(4):421-427.

Burgel, P.-R. and J.A. Nadel, Epidermal growth factor receptor-mediated innate immune responses and their roles in airway diseases. Eur Resp J, 2008. 32(4):1068-1081.

Ciardiello, F., and Tortora, G. (2008). EGFR antagonists in cancer treatment. N Engl J Med, 2008. 358(11):1160–1174.

Casalino-Matsuda, S.M., et al., Role of hyaluronan and reactive oxygen species in tissue kallikrein-mediated epidermal growth factor receptor activation in human airways. J Biol Chem, 2004. 279(20):21606-21616.

Chen, H., et al., Epidermal growth factor receptor in adult retinal neurons of rat, mouse, and human. J Comp Neurol 2007. 500(2):299-310.

de Boer, W.I., et al., Expression of epidermal growth factors and their receptors in the bronchial epithelium of subjects with chronic obstructive pulmonary disease. American Journal of Clinical Pathology, 2006. 125(2):184-192.

Deshmukh, H.S., et al., Acrolein-activated matrix metalloproteinase 9 contributes to persistent mucin production. Am J Resp Cell Mol Biol, 2008. 38(4):446-454.

Deshmukh, H.S., et al., Matrix metalloproteinase-14 mediates a phenotypic shift in the airways to increase mucin production. Am J Respir Crit Care Med, 2009. 180(9):834-845.

DeYulia, G.J., et al., Hydrogen peroxide generated extracellularly by receptor–ligand interaction facilitates cell signaling. PNAS, 2005. 102(14):5044-5049.

DeYulia, G.J. and J.M. Cárcamo, EGF receptor-ligand interaction generates extracellular hydrogen peroxide that inhibits EGFR-associated protein tyrosine phosphatases. Biochem Biophys Res Commun, 2005. 334(1):38-42.

Goldkorn, T., et al., EGF-receptor phosphorylation and signaling are targeted by H2O2 redox stress. Am J Resp Cell Mol Biol, 1998. 19(5):786-798.

Hackel, P.O., et al., Epidermal growth factor receptors: critical mediators of multiple receptor pathways. Curr Opin Cell Biol, 1999. 11(2):184-189.

Higashiyama, S., et al., Membrane-anchored growth factors, the epidermal growth factor family: Beyond receptor ligands. Cancer Sci, 2008. 99(2):214-220.

Jorissen, R.N., et al., Epidermal growth factor receptor: mechanisms of activation and signalling. Exp Cell Res 2003. 284(1):31–53.

Kiley, S.C., and Chevalier, R.L., Species differences in renal Src activity direct EGF receptor regulation in life or death response to EGF. Am J. Physiol Renal Physiol, 2007. 293(3):F895–F903.

Kim, J.H., et al., Effects of matrix metalloproteinase inhibitor on LPS-induced goblet cell metaplasia. Am J Physiol Lung Cell Mol Physiol, 2004. 287(1):L127-L133.

Kim, S., et al., E-cadherin promotes EGFR-mediated cell differentiation and MUC5AC mucin expression in cultured human airway epithelial cells. Am J Physiol Lung Cell Mol Physiol, 2005. 289(6):L1049-L1060.

Kohri, K., et al., Neutrophil elastase induces mucin production by ligand-dependent epidermal growth factor receptor activation. Am J Physiol Lung Cell Mol Physiol, 2002. 283(3):L531-L540.

Lee, Y.C., et al., 2,3,7,8-Tetrachlorodibenzo-p-dioxin–Induced MUC5AC Expression Aryl Hydrocarbon Receptor-Independent/EGFR/ERK/p38-Dependent SP1-Based Transcription. Am J Respir Cell Mol Biol, 2011. 45(2):270-276.

Lemjabbar, H., et al., Tobacco smoke-induced lung cell proliferation mediated by tumor necrosis factor alpha-converting enzyme and amphiregulin. J Biol Chem, 2003. 278(28):26202-7.

Marinaş, A., et al., Expression of Epidermal Growth Factor (EGF) and its receptors (EGFR1 and EGFR2) in chronic bronchitis. Rom J Morphol Embryol, 2011. 53(4):957-966.

Nexø, E., and Hansen, H.F. (1985). Binding of epidermal growth factor from man, rat and mouse to the human epidermal growth factor receptor. Biochim Biophys Acta 843(1-2):101–106.

O’Donnell, R., et al., Expression of ErbB receptors and mucins in the airways of long term current smokers. Thorax, 2004. 59(12):1032-1040.

Paulsen, C.E., et al., Peroxide-dependent sulfenylation of the EGFR catalytic site enhances kinase activity. Nat Chem Biol, 2011. 8(1):57-64.

Polosa, R., et al., Expression of c-erbB receptors and ligands in human bronchial mucosa. Am J Resp Cell Mol Biol 1999. 20(5):914-923.

Ravid, T., et al., Epidermal growth factor receptor activation under oxidative stress fails to promote c-Cbl mediated down-regulation. J Biol Chem, 2002. 277(34):31214-31219.

Rumelhard, M., et al., Expression and role of EGFR ligands induced in airway cells by PM2.5 and its components. Eur Resp J, 2007. 30(6):1064-1073.

Shao, M.X.G., et al., Cigarette smoke induces MUC5AC mucin overproduction via tumor necrosis factor-alpha-converting enzyme in human airway epithelial (NCI-H292) cells. Am J Physiol Lung Cell Mol Physiol, 2004. 287(2), L420–L427.

Shao, M.X.G. and J.A. Nadel, Neutrophil Elastase Induces MUC5AC Mucin Production in Human Airway Epithelial Cells via a Cascade Involving Protein Kinase C, Reactive Oxygen Species, and TNF-α-Converting Enzyme. J Immunol, 2005. 175(6):4009-4016.

Shim, J.J., et al., IL-13 induces mucin production by stimulating epidermal growth factor receptors and by activating neutrophils. Am J Physiol Lung Cell Mol Physiol, 2001. 280(1):L134-L140.

Takeyama, K., et al., Oxidative stress causes mucin synthesis via transactivation of epidermal growth factor receptor: role of neutrophils. J Immunol, 2000. 164(3):1546-1552.

Takeyama, K., et al., Activation of epidermal growth factor receptors is responsible for mucin synthesis induced by cigarette smoke. Am J Physiol Lung Cell Mol Physiol, 2001. 280(1):L165-L172.

Truong, T.H. and K.S. Carroll, Redox regulation of EGFR signaling through cysteine oxidation. Biochemistry, 2012. 51(50):9954-9965.

Truong, T.H., et al., Molecular basis for redox activation of epidermal growth factor receptor kinase. Cell Chem Biol 2016. 23(7):837-848.

Val, S., et al., Fine PM induce airway MUC5AC expression through the autocrine effect of amphiregulin. Arch Toxicol, 2012. 86(12):1851-1859.

Van Winkle, L.S., J.M. Isaac, and C.G. Plopper, Distribution of epidermal growth factor receptor and ligands during bronchiolar epithelial repair from naphthalene-induced Clara cell injury in the mouse. Am J Pathol, 1997. 151(2):443-459.

Yoshisue, H. and K. Hasegawa, Effect of MMP/ADAM inhibitors on goblet cell hyperplasia in cultured human bronchial epithelial cells. Biosci Biotechnol Biochem, 2004. 68(10):2024-2031.

Yu, H., et al., Regulation of Cigarette Smoke-Induced Mucin Expression by Neuregulin1β/ErbB3 Signalling in Human Airway Epithelial Cells. Basic Clin Pharmacol Toxicol, 2011. 109(1):63-72.

Yu, Q., et al., Caveolin-1 aggravates cigarette smoke extract-induced MUC5AC secretion in human airway epithelial cells. Intl J Mol Med, 2015. 35(5):1435-1442.