Upstream eventActivation, EGFR
Increase, Mucin production
Key Event Relationship Overview
AOPs Referencing Relationship
|AOP Name||Adjacency||Weight of Evidence||Quantitative Understanding|
|EGFR Activation Leading to Decreased Lung Function||non-adjacent||High||High|
Life Stage Applicability
Key Event Relationship Description
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). 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 (Lemjabbar et al., 2003; Kim et al., 2005; Hackel et al, 1999) and facilitates epithelial wound repair (Burgel and Nadel, 2004; van Winkle et al., 1997; Allahverdian et al., 2010). In the airways, EGFR signaling has been identified as the key pathway that leads to airway mucus hypersecretion (Burgel and Nadel, 2004).
Evidence Supporting this KER
EGFR can be activated by bacterial infection, EGFR ligands, exposure to cigarette smoke and other sources of ROS, leading to increased mucin production via Ras/Raf-1/MEK/ERK-mediated activation of the Sp1 transcription factor and/or increase in cell proliferation, all of which can be suppressed at least partially in the presence of EGFR inhibitors (Sydlik et al., 2006; Casalino-Matsuda et al., 2006; Takeyama et al., 2008; Perrais et al., 2002; Hewson et al., 2004; Wu et al., 2007; Barbier et al., 2012; Lee et al., 2011).
Multiple studies showed that ligand- or ROS-mediated EGFR activation leads to increased goblet cell numbers and mucin production in rat airway epithelia (Shim et al., 2001; Lee et al., 2000), normal human bronchial epithelial cells grown at the air liquid interface (Casalino-Matsuda et al., 2006; Hao et al., 2014), and in a human pulmonary mucoepidermoid carcinoma cell line (NCI-H292) (Takeyama et al., 2008; Takeyama et al., 1999).
Include consideration of temporal concordance here
Studies show a dose-dependent increase in mucin production in response to EGFR activation by IL13 or infection (Shim et al., 2001), (Hao et al., 2014). Dose-response concordance is shown with mycoplasma pneumoniae infection inducing EGFR 5-fold while inducing downstream KE mucin production 2-fold (Hao et al., 2014).
Uncertainties and Inconsistencies
Quantitative Understanding of the Linkage
Daily treatment of primary human bronchial epithelial cells with 0.6 mM xanthine and 0.5 units xanthine oxidase for 3 days nearly doubled the levels of phosphorylated EGFR and increased expression of MUC5AC mRNA by approx. 2-fold and that of MUC5AC protein by ca. 30%, and these responses could be at least partially prevented by pre-incubation with anti-EGFR antibodies (Casalino-Matsuda et al., 2006).
Increased MUC5AC expression (ca. 5-fold) was seen in the tracheal, but not the lung epithelium of C57Bl/6 mice 48 hours after instillation PM2.5. This effect was significant with 50 microg, but not with 10 microg PM2.5. Moreover, PM2.5 dose-dependently increased MUC5AC expression in H292 and primary human bronchial epithelial cells grown as monolayer, with significant increases of ca. 10- and 8-fold above that of control observed with concentrations of > 5 microg/cm2. At a concentration of 10 microg/cm2, MUC5AC mRNA level in H292 cells peaked at >30 times that of control after 24 hours of treatment and decreased to approx. 20-fold that of control at 36 hours. When primary cells were differentiated the air-liquid interface, MUC5AC expression also increased in a PM2.5-dose-dependent manner. However, 10 microg/cm2 PM2.5 were necessary to induce a significant, maximal response (ca.3-fold increase). Importantly, 10 microM AG1478 or 0.5 microg/microL neutralizing EGFR antibody reduced the response to 10 microg/cm2 PM2.5 in H292 cells by ca. 50%. (Val et al., 2012).
Mycoplasma pneumoniae M129 infection of H292 cells at MOIs of both 25:1 and 50:1 resulted in a ca. 1.5- and 2.2-fold increase in MUC5AC mRNA expression. Similarly, MUC5B mRNA was induced approx. 2.2- and 2.5-fold. Under the same infection conditions, EGFR phosphorylation increased 4- and 6-fold in H292 cells, and treatment with 10 microM AG1478 attenuated the induction of MUC5AC and MUC5B by M. pneumoniae M129. In addition, in 3D organotypic bronchial tissues, infection with M. pneumoniae M129 caused 6.8- and 5-fold increases in MUC5AC and MUC5B protein expression (Hao et al., 2011).
Acrolein exposure of FVB/NJ mice at 2 ppm for 6 hours per day, 5 days a week for 4 weeks increased lung Muc5ac RNA and protein levels approx. 4-fold. Gavage of 100 mg/kg erlotinib after every exposure abolished this effect (Deshmukh et al., 2008).
IL-13 instillation in F344 rats induced mucin expression in the carina in a dose-dependent fashion. 50 ng IL-13 were necessary to significantly raise the % mucin-expressing epithelial area significantly above background (<10% in controls vs 15% in treated rats), and % mucin-expressing epithelial area was maximal at the highest tested concentration, 500 ng. Treatment of animals with BIBX1522 prior to and following instillation dose-dependently decreased mucin expression, with a maximal decrease to a level nearing that of control animals seen at 30 mg/kg (Shi et al., 2001).
Known modulating factors
Known Feedforward/Feedback loops influencing this KER
Domain of Applicability
Many studies in human, mouse, and rat showed EGFR activation leading to an increase in mucus production.
Allahverdian, S., Wang, A., Singhera, G.K., Wong, B.W., and Dorscheid, D.R. (2010). Sialyl Lewis X modification of the epidermal growth factor receptor regulates receptor function during airway epithelial wound repair. Clin Exp Allergy 40, 607-618.
Barbier, D., Garcia-Verdugo, I., Pothlichet, J., Khazen, R., Descamps, D., Rousseau, K., Thornton, D., Si-Tahar, M., Touqui, L., Chignard, M., et al. (2012). Influenza A Induces the Major Secreted Airway Mucin MUC5AC in a Protease–EGFR–Extracellular Regulated Kinase–Sp1–Dependent Pathway. Am J Respir Cell Mol Biol 47, 149–157.
Burgel, P., and Nadel, J. (2004). Roles of epidermal growth factor receptor activation in epithelial cell repair and mucin production in airway epithelium. Thorax 59, 992-996.
Casalino-Matsuda, S.M., Monzón, M.E., and Forteza, R.M. (2006). Epidermal growth factor receptor activation by epidermal growth factor mediates oxidant-induced goblet cell metaplasia in human airway epithelium. Am J Respir Cell Mol Biol 34, 581–591.
Deshmukh, H.S., Shaver, C., Case, L.M., Dietsch, M., Wesselkamper, S.C., Hardie, W.D., Korfhagen, T.R., Corradi, M., Nadel, J.A., and Borchers, M.T. (2008). Acrolein-activated matrix metalloproteinase 9 contributes to persistent mucin production. Am J Resp Cell Mol Biol 38, 446-454.
Hackel, P.O., Zwick, E., Prenzel, N., and Ullrich, A. (1999). Epidermal growth factor receptors: critical mediators of multiple receptor pathways. Curr Opin Cell Biol 11, 184-189.
Hao, Y., Kuang, Z., Jing, J., Miao, J., Mei, L.Y., Lee, R.J., Kim, S., Choe, S., Krause, D.C., and Lau, G.W. (2014). Mycoplasma pneumoniae Modulates STAT3-STAT6/EGFR-FOXA2 Signaling To Induce Overexpression of Airway Mucins. Infect Immun 82, 5246–5255.
Higashiyama, S., Iwabuki, H., Morimoto, C., Hieda, M., Inoue, H., and Matsushita, N. (2008). Membrane-anchored growth factors, the epidermal growth factor family: Beyond receptor ligands. Cancer Sci 99, 214-220.
Hewson, C., Edbrooke, M., and Johnston, S. (2004). PMA induces the MUC5AC respiratory mucin in human bronchial epithelial cells, via PKC, EGF/TGF-alpha, Ras/Raf, MEK, ERK and Sp1-dependent mechanisms. J Mol Biol 344, 683–695.
Kim, S., Schein, A.J., and Nadel, J.A. (2005). E-cadherin promotes EGFR-mediated cell differentiation and MUC5AC mucin expression in cultured human airway epithelial cells. Am J Physiol Lung Cell Mol Physiol 289, L1049-L1060.
Lee, H.-M., Takeyama, K., Dabbagh, K., Lausier, J.A., Ueki, I.F., and Nadel, J.A. (2000). Agarose plug instillation causes goblet cell metaplasia by activating EGF receptors in rat airways. Am J Physiol Lung Cell Mol Physiol 278, L185–L192.
Lee, Y.C., Oslund, K.L., Thai, P., Velichko, S., Fujisawa, T., Duong, T., Denison, M.S., and Wu, R. (2011). 2,3,7,8-Tetrachlorodibenzo-p-dioxin–Induced MUC5AC Expression. Am J Respir Cell Mol Biol 45, 270–276.
Lemjabbar, H., Li, D., Gallup, M., Sidhu, S., Drori, E., and Basbaum, C. (2003). Tobacco smoke-induced lung cell proliferation mediated by tumor necrosis factor alpha-converting enzyme and amphiregulin. J Biol Chem 278, 26202-26207.
Perrais, M., Pigny, P., Copin, M., Aubert, J., and Van Seuningen, I. (2002). Induction of MUC2 and MUC5AC mucins by factors of the epidermal growth factor (EGF) family is mediated by EGF receptor/Ras/Raf/extracellular signal-regulated kinase cascade and Sp1. J Biol Chem 277, 32258–32267.
Shim, J.J., Dabbagh, K., Ueki, I.F., Dao-Pick, T., Burgel, P.R., Takeyama, K., Tam, D.C., and Nadel, J.A. (2001). IL-13 induces mucin production by stimulating epidermal growth factor receptors and by activating neutrophils. Am J Physiol Lung Cell Mol Physiol 280, L134–L140.
Sydlik, U., Bierhals, K., Soufi, M., Abel, J., Schins, R.P.F., and Unfried, K. (2006). Ultrafine carbon particles induce apoptosis and proliferation in rat lung epithelial cells via specific signaling pathways both using EGF-R. Am J Physiol Lung Cell Mol Physiol 291, L725–L733.
Takeyama, K., Dabbagh, K., Lee, H., Agustí, C., Lausier, J., Ueki, I., Grattan, K., and Nadel, J. (1999). Epidermal growth factor system regulates mucin production in airways. Proc Natl Acad Sci USA 96, 3081–3086.
Takeyama, K., Tamaoki, J., Kondo, M., Isono, K., and Nagai, A. (2008). Role of epidermal growth factor receptor in maintaining airway goblet cell hyperplasia in rats sensitized to allergen. Clin Exp Allergy 38, 857–865.
Val, S., Belade, E., George, I., Boczkowski, J., and Baeza-Squiban, A. (2012). Fine PM induce airway MUC5AC expression through the autocrine effect of amphiregulin. Arch Toxicol 86, 1851-1859.
Van Winkle, L.S., Isaac, J.M., and Plopper, C.G. (1997). Distribution of epidermal growth factor receptor and ligands during bronchiolar epithelial repair from naphthalene-induced Clara cell injury in the mouse. Am J Pathol 151, 443.
Wu, D.Y., Wu, R., Reddy, S.P., Lee, Y.C., and Chang, M.M.-J. (2007). Distinctive epidermal growth factor receptor/extracellular regulated kinase-independent and -dependent signaling pathways in the induction of airway mucin 5B and mucin 5AC expression by phorbol 12-myristate 13-acetate. Am J Pathol 170, 20–32.