TY - JOUR
T1 - Methylindoles and methoxyindoles are agonists and antagonists of human aryl hydrocarbon receptor
AU - Stepankova, Martina
AU - Bartonkova, Iveta
AU - Jiskrova, Eva
AU - Vrzal, Radim
AU - Mani, Sridhar
AU - Kortagere, Sandhya
AU - Dvorak, Zdenek
N1 - Funding Information:
Financial support from the Czech Science Foundation [Grant P303/12/G163]; Palacky University in Olomouc [Grants PrF-2017-004 and PrF-2018-005]; Operational Programme Research, Development and Education, European Regional Development Fund, Ministry of Education, Youth and Sports of the Czech Republic [Grant CZ.02.1.01/0.0/0.0/16_019/0000754]; Institute for Clinical and Translational Research Pilot Award [AECOM]; Broad Medical Research Program at Crohn’s & Colitis Foundation of America [Grant 362520]; Department of Defence Partnering PI [Grants PR160167, R43DK105694, and P30DK041296]; and National Institutes of Health [Grants CA127231 and CA161879], National Institutes of Health Diabetes Research Center [Grant P30 DK020541], and National Institutes of Health Cancer Center [Grant P30 CA013330] is acknowledged. https://doi.org/10.1124/mol.118.112151. s This article has supplemental material available at molpharm. aspetjournals.org.
Publisher Copyright:
© 2018 by The American Society for Pharmacology and Experimental Therapeutics.
PY - 2018/6/1
Y1 - 2018/6/1
N2 - Novel methylindoles were identified as endobiotic and xenobiotic ligands of the human aryl hydrocarbon receptor (AhR). We examined the effects of 22 methylated and methoxylated indoles on the transcriptional activity of AhRs. Employing reporter gene assays in AZ-AHR transgenic cells, we determined full agonist, partial agonist, or antagonist activities of tested compounds, having substantially variable EC50, IC50, and relative efficacies. The most effective agonists (EMAX relative to 5 nM dioxin) of the AhR were 4-Me-indole (134%), 6-Me-indole (91%), and 7-MeO-indole (80%), respectively. The most effective antagonists of the AhR included 3-Me-indole (IC50; 19 mM), 2,3-diMe-indole (IC50; 11 mM), and 2,3,7-triMe-indole (IC50; 12 mM). Reverse transcription polymerase chain reaction analyses of CYP1A1 mRNA in LS180 cells confirmed the data from gene reporter assays. The compound leads, 4-Me-indole and 7-MeO-indole, induced substantial nuclear translocation of the AhR and enriched binding of the AhR to the CYP1A1 promoter, as observed using fluorescent immunohistochemistry and chromatin immunoprecipitation assays, respectively. Molecular modeling and docking studies suggest the agonists and antagonists likely share the same binding pocket but have unique binding modes that code for their affinity. Binding pocket analysis further revealed that 4-methylindole and 7-methoxyindole can simultaneously bind to the pocket and produce synergistic interactions. Together, these data show a dependence on subtle and specific chemical indole structures as AhR modulators and furthermore underscore the importance of complete evaluation of indole compounds as nuclear receptor ligands.
AB - Novel methylindoles were identified as endobiotic and xenobiotic ligands of the human aryl hydrocarbon receptor (AhR). We examined the effects of 22 methylated and methoxylated indoles on the transcriptional activity of AhRs. Employing reporter gene assays in AZ-AHR transgenic cells, we determined full agonist, partial agonist, or antagonist activities of tested compounds, having substantially variable EC50, IC50, and relative efficacies. The most effective agonists (EMAX relative to 5 nM dioxin) of the AhR were 4-Me-indole (134%), 6-Me-indole (91%), and 7-MeO-indole (80%), respectively. The most effective antagonists of the AhR included 3-Me-indole (IC50; 19 mM), 2,3-diMe-indole (IC50; 11 mM), and 2,3,7-triMe-indole (IC50; 12 mM). Reverse transcription polymerase chain reaction analyses of CYP1A1 mRNA in LS180 cells confirmed the data from gene reporter assays. The compound leads, 4-Me-indole and 7-MeO-indole, induced substantial nuclear translocation of the AhR and enriched binding of the AhR to the CYP1A1 promoter, as observed using fluorescent immunohistochemistry and chromatin immunoprecipitation assays, respectively. Molecular modeling and docking studies suggest the agonists and antagonists likely share the same binding pocket but have unique binding modes that code for their affinity. Binding pocket analysis further revealed that 4-methylindole and 7-methoxyindole can simultaneously bind to the pocket and produce synergistic interactions. Together, these data show a dependence on subtle and specific chemical indole structures as AhR modulators and furthermore underscore the importance of complete evaluation of indole compounds as nuclear receptor ligands.
UR - http://www.scopus.com/inward/record.url?scp=85052989368&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85052989368&partnerID=8YFLogxK
U2 - 10.1124/mol.118.112151
DO - 10.1124/mol.118.112151
M3 - Article
C2 - 29626056
AN - SCOPUS:85052989368
VL - 93
SP - 631
EP - 644
JO - Molecular Pharmacology
JF - Molecular Pharmacology
SN - 0026-895X
IS - 6
ER -