Upstream eventActivation, EGFR
Increase, Proliferation of goblet cells
Key Event Relationship Overview
AOPs Referencing Relationship
|AOP Name||Adjacency||Weight of Evidence||Quantitative Understanding|
|EGFR Activation Leading to Decreased Lung Function||adjacent||Moderate||Low|
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).
Evidence Supporting this KER
Activation of EGFR through direct binding of its ligands EGF, TGFA or epigen or indirectly by oxidative stress following exposure to endotoxin, ozone, ultrafine particles or cigarette smoke induces airway epithelial cell proliferation. While not all studies specifically identify goblet cells as the proliferating cell population, others do - at least indirectly by quantifying the increase in MUC5AC expressing cells (Booth et al., 2001; Booth et al., 2007; Taniguchi et al., 2011; Sydlik et al., 2006; Tamaoki et al., 2004; Tesfaigzi et al., 1998; Tesfaigzi et al., 2004; Harris et al., 2005; Tamiguchi et al., 2001).
Although there are no studies providing direct evidence for proliferation of goblet cells in the lung following EGFR activation, there is direct in vitro evidence in conjunctival goblet cells (Gu et al., 2008; Shatos et al., 2008) and in murine embryonic colon (Duh et al., 2000). However, multiple studies indirectly demonstrate a link between exposure to stressors known to cause oxidative stress-mediated activation of EGFR and increases in goblet cell number.
Studies specific to goblet cells have been performed in cultured rat conjunctival goblet cells where EGFR ligands EGF, TGFA, HB-EGF stimulate an increase in phosphorylated EGFR as well as proliferation (Gu et al., 2008) and in human cultured conjunctival goblet cells where EGF caused a dose-dependent increase in proliferation (Shatos et al., 2003). In lung, studies either look generally at epithelial cell proliferation, not specifically goblet cells, or measure an increase in goblet cells, not specifically proliferation (Casalino-Matsuda et al., 2006). IL13-induced proliferation is mediated by EGFR in mouse primary airway epithelial cells via indiction of the EGFR ligand epigen, and this proliferation could be inhibited by EGFR blockade (Taniguchi et al., 2011). Proliferation of rat lung epithelial cells increased dose dependently following treatment with both ultrafine carbon black and amorphous silica particles (14 nm diameter), but not larger carbon black particles (260 nm diameter) (Sydlik et al., 2006). IL13-induced human bronchial epithelial cell proliferation is mediated by EGFR activation and decreases with increasing dose of EGFR inhibitor AG1478 (Booth et al., 2001; Booth et al., 2007).
Uncertainties and Inconsistencies
The majority of studies supporting this KER did not specifically measure goblet cell proliferation. Instead, many studies measured an increase in mucin production upon EGFR activation, equating this with an increase in goblet cell numbers (Takeyama, et al. 2008; Shim et al. 2001; Casalino-Matsuda et al. 2006).
Quantitative Understanding of the Linkage
Daily xanthine/xanthine oxidase treatment of human primary bronchial epithelial cells grown at the at the air-liquid interface (ALI) for 3 days increased the number of MUC5AC-positive cells (from 3.3 ± 1.2% (PBS) to 21.6 ± 3.4%). This increase was prevented by pretreatment with anti-EGFR antibodies (Casalino-Matsuda et al., 2006). Treatment of human primary bronchial epithelial cells with 10-100 ng/mL amphiregulin or HB-EGF for 24 hours increased proliferation (Hirota et al., 2012). Proliferation of murine primary airway epithelial cells grown at the ALI with IL-13 was inhibited in the presence of EGFR inhibitor AG1478 (Taniguchi et al., 2011).
Proliferation of rat conjunctival goblet cells was observed following stimulation with 100 microM EGF, TGFA or HB-EGF after 14 hours, peaking at 18 hours (Gu et al., 2008). In another study, 24-hour EGF treatment of rat conjunctival goblet cells increased proliferation by nearly 5-fold (Shatos et al., 2008).
Approx. 50% of AB/PAS-positive cells were BrdU-positive in the airways of rats at day 2 following instillation of F344 rats with 1 mg LPS, suggesting that they may have been derived from proliferating cells (Tesfaigzi et al., 2004).
Treatment of primary human bronchial epithelial cells, grown at the air-liquid interface for 9 days, with 5 ng/mL TGFA or 10 ng/mL IL-13 for 24 hours resulted in 1.5- to 2-fold increases in cell numbers (by [3H]thymidine incorporation). These increases were prevented by co-incubation with the EGFR inhibitor AG1478, with maximal decreases in cell numbers seen at 5 ng/mL AG1478 (Booth et al., 2001a). Although this study did not specify the affected cell type as goblet cells, another study by the same group using the same model showed that the percentage of AB/PAS–positive, mucus-producing cells increased following IL-13 treatment (Booth et al., 2001b).
(Taniguchi et al., 2011).
Known modulating factors
Known Feedforward/Feedback loops influencing this KER
Domain of Applicability
Epithelial cell proliferation mediated by EGFR has been studied in human (Booth et al., 2001; Booth et al., 2007), mouse (Taniguchi et al., 2011) and rat (Sydlik et al., 2006).
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.
Booth, B.W., Adler, K.B., Bonner, J.C., Tournier, F., and Martin, L.D. (2001a). Interleukin-13 induces proliferation of human airway epithelial cells in vitro via a mechanism mediated by transforming growth factor-alpha. Am J Respir Cell Mol Biol 25, 739–743.
Booth, B., J. C. Bonner, K. B. Adler, and L. D. Martin. (2001b). Autocrine production of TGF mediates interleukin 13-induced proliferation of human airway epithelial cells during development of a mucous phenotype in vitro. Am J Respir Crit Care Med 163:A738.
Booth, B.W., Sandifer, T., Martin, E.L., and Martin, L.D. (2007). IL-13-induced proliferation of airway epithelial cells: mediation by intracellular growth factor mobilization and ADAM17. Respir Res 8, 51.
Casalino-Matsuda, S., Monzón, M., and Forteza, R. (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.
Duh, G., Mouri, N., Warburton, D., and Thomas, D.W. (2000). EGF regulates early embryonic mouse gut development in chemically defined organ culture. Pediatr Res 48, 794–802.
Gu, J., Chen, L., Shatos, M.A., Rios, J.D., Gulati, A., Hodges, R.R., and Dartt, D.A. (2008). Presence of EGF growth factor ligands and their effects on cultured rat conjunctival goblet cell proliferation. Exp Eye Res 86, 322–334.
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.
Harris, J.F., Fischer, M.J., Hotchkiss, J.R., Monia, B.P., Randell, S.H., Harkema, J.R., and Tesfaigzi, Y. (2005). Bcl-2 sustains increased mucous and epithelial cell numbers in metaplastic airway epithelium. Am J Respir Crit Care Med 171, 764-772.
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.
Hirota, N., Risse, P.A., Novali, M., McGovern, T., Al-Alwan, L., McCuaig, S., Proud, D., Hayden, P., Hamid, Q., and Martin, J.G. (2012). Histamine may induce airway remodeling through release of epidermal growth factor receptor ligands from bronchial epithelial cells. FASEB J 26, 1704-1716.
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.
Lamb, D., and Reid, L. (1968). Mitotic rates, goblet cell increase and histochemical changes in mucus in rat bronchial epithelium during exposure to sulphur dioxide. J Pathol Bacteriol 96, 97–111.
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.
Shatos, M.A., Ríos, J.D., Horikawa, Y., Hodges, R.R., Chang, E.L., Bernardino, C.R., Rubin, P.A.D., and Dartt, D.A. (2003). Isolation and characterization of cultured human conjunctival goblet cells. Invest Ophthalmol Vis Sci 44, 2477–2486.
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.
Shimizu, T., Takahashi, Y., Kawaguchi, S., and Sakakura, Y. (1996). Hypertrophic and metaplastic changes of goblet cells in rat nasal epithelium induced by endotoxin. Am J Respir Crit Care Med 153, 1412–1418.
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., 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.
Tamaoki, J., Isono, K., Takeyama, K., Tagaya, E., Nakata, J., and Nagai, A. (2004). Ultrafine carbon black particles stimulate proliferation of human airway epithelium via EGF receptor-mediated signaling pathway. Am J Physiol Lung Cell Mol Physiol 287, L1127–L1133.
Taniguchi, K., Yamamoto, S., Aoki, S., Toda, S., Izuhara, K., and Hamasaki, Y. (2011). Epigen is induced during the interleukin-13-stimulated cell proliferation in murine primary airway epithelial cells. Exp Lung Res 37, 461–470.
Tesfaigzi, J., Hotchkiss, J.A., and Harkema, J.R. (1998). Expression of the Bcl-2 protein in nasal epithelia of F344/N rats during mucous cell metaplasia and remodeling. AM J Resp Cell Mol Biol 18, 794-799.
Tesfaigzi, Y., Harris, J.F., Hotchkiss, J.A., and Harkema, J.R. (2004). DNA synthesis and Bcl-2 expression during development of mucous cell metaplasia in airway epithelium of rats exposed to LPS. Am J Physiol Lung Cell Mol Physiol 286, L268-L274.
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, 443-459.