EGF receptor signaling blocks aryl hydrocarbon receptor-mediated transcription and cell differentiation in human epidermal keratinocytes

Abstract

Fig. 4. Opposing effects of TCDD and EGF on differentiation of NHEKs. (A)NHEKs were grown to confluence, and basal medium, or medium with ␣-naphthoflavone (NF, 1 M) was added 24 h before treatment. CEs were isolated after treatment with either 0.1% DMSO or TCDD (10 nM) for 5 days. (B) NHEKs were grown to confluence, and basal medium with or without EGF (10 ng/mL) was added 24 h before treatment. CEs were isolated after treatment with either 0.1% DMSO or TCDD (10 nM) for 5 days. (C) NHEKs were grown to confluence, and basal medium, or medium with EGF (10 ng/mL), was added 24 h before treatment. CEs were isolated after treatment with either 0.1% DMSO or TCDD (10 nM) in the presence or absence of PD153035 (300 nM) for 5 days. (A-C) The values for CEs are a mean of triplicate samples Ϯ SD. (D-G) NHEKs were grown to a cell density of either 50% or 100% confluence before basal medium, or medium with EGF (10 ng/mL), was added for 24 h before treatment. Total mRNA was isolated after treatment with either control vehicle (0.1% DMSO) or TCDD (10 nM) for 24 h. Real-time PCR was used to determine the relative expression of each indicated gene (y axis). Levels of mRNA [mean (n ϭ 3) Ϯ SD] are expressed in units relative to the minimum, given a value of 1. (A-G) The a indicates that the value from treatment with TCDD is significantly different from the DMSO control; the b indicates that the value from cotreatment with TCDD and NF is significantly different from TCDD alone; the c indicates that the value from cotreatment with TCDD and EGF is significantly different from with TCDD alone; the d indicates that the value from treatment with TCDD, EGF, and PD153035 is significantly different from treatment with TCDD and EGF; and the e indicates that treatment with EGF is significantly different from DMSO control treatment. For each of these comparisons, P Յ 0.01 by Student's t test. Comparisons made in D-G are within the group grown to a cell density of 100% confluence.

Epidermal Growth Factor Receptor Kinase Inhibitors Synergize with TCDD to Induce CYP1A1/1A2 in Human Breast Epithelial MCF10A Cells

“…In the case of the keratinocyte study, chromatin immunoprecipitation assays indicated that EGF supplementation did not disrupt CYP1A1 promoterAhR binding. Instead, EGF supplementation suppressed the recruitment of the coactivating protein p300 to the AhR-XRE complex (Sutter et al, 2009).…”

“…Specifically, Sutter et al (2009) reported that the addition of EGF to confluent primary human keratinocyte cultures markedly suppressed the induction of CYP1A1 by TCDD, as well as transcription initiated from reporter constructs Cultures were maintained in complete medium, or shifted to deficient medium, and left untreated, or treated with 10 nM TCDD 6 500 nM gefitinib or 500 nM AG1478. Cultures were treated with gefitinib or AG1478 either 1 or 2 hours after the medium shift.…”

“…What is known is derived from analyses of TCDD effects on developmental processes in transforming growth factor-a-or EGF-deficient mice (Bryant et al, 2001;Abbott et al, 2003), and the effects of exogenously added EGF on the mRNA and protein contents of AhR-responsive genes (e.g., primarily CYP1A1/1A2) in cultured cells (Bachleda et al, 2009;Sutter et al, 2009). The results of these latter studies suggest that the activated EGFR mutes AhR signaling.…”

The Malassezia Genus in Skin and Systemic Diseases

“…Higher production rates of aryl hydrocarbon receptor (AhR) ligands in vitro by M. furfur have been associated with seborrheic dermatitis isolates (108). AhR is found in sebocytes (169), and its function is modified by epidermal growth factor receptor (EGFR) (268,301). The latter probably has a seborrheic distribution, as antibodies or small molecules that block its function cause a folliculocentric eruption with a seborrheic distribution (36), and the interplay of these two receptors was proposed previously (105).…”

Plant Polyphenols Regulate Chemokine Expression and Tissue Repair in Human Keratinocytes Through Interaction with Cytoplasmic and Nuclear Components of Epidermal Growth Factor Receptor System

“…eratinocytes are not only primary sensors of stressful conditions but also major players of the extremely complex response in the skin conducting an orchestrated recruitment and functions of the immune cells, fibroblasts, and vascular cells involved in the inflammatory responses and wound healing (30,38). Epidermal growth factor receptor (EGFR) located on the cellular membrane of keratinocytes is widely recognized as a key regulator of numerous essential processes underlying skin development, homeostasis, and repair (30,35,38,39).…”