Aryl hydrocarbon receptor is a transcriptional activator of the human breast cancer resistance protein (BCRP/ABCG2).
Breast cancer resistance protein (BCRP/ABCG2) is a membrane-bound efflux transporter important in cellular detoxification and multidrug resistance. Some aryl hydrocarbon receptor (AHR) agonists were reported to induce BCRP expression in human colon carcinoma cells. However, a direct involvement of AHR transcriptional regulation remains unexplored. In this study, we show that BCRP induction by AHR ligands occurs in human intestinal, liver, and mammary carcinoma cells and in primary colonocytes and hepatocytes. Increased BCRP transporter activity consistent with gene induction was also evident in the Caco2 subclone C2bbe1 cells. Using RNA interference and ectopic expression techniques to manipulate cellular AHR status, we confirmed AHR dependence of ABCG2 gene regulation. By gene promoter analysis, chromatin immunoprecipitation, and electrophoretic mobility shift assays, an active, proximal dioxin-response element at -194/-190 base pairs upstream of the transcription start site of the human ABCG2 gene was identified. Despite a common observation in human-derived cells, our in vitro and in vivo studies supported by phylogenetic footprinting analysis did not find that mouse Abcg2 is subject to AHR regulation. We conclude that AHR is a direct transcriptional regulator of human BCRP and provide an unprecedented role of AHR in cellular adaptive response and cytoprotection by up-regulating an important ATP-binding cassette efflux transporter.
Tan
Kah Poh
KP
Physiology and Experimental Medicine Program, University of Toronto, Ontario, Canada.
Wang
Bernice
B
Yang
Mingdong
M
Boutros
Paul C
PC
Macaulay
Jane
J
Xu
Haibo
H
Chuang
Andrew I
AI
Kosuge
Kazuhiro
K
Yamamoto
Mika
M
Takahashi
Shinichiro
S
Wu
Alex M L
AM
Ross
Douglas D
DD
Harper
Patricia A
PA
Ito
Shinya
S
D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D045744:Cell Line, Tumor; D017931:DNA Primers; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D009363:Neoplasm Proteins / Q000235:genetics*; D010802:Phylogeny; D011247:Pregnancy; D018336:Receptors, Aryl Hydrocarbon / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015534:Trans-Activators / Q000502:physiology*
C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D017931:DNA Primers; D009363:Neoplasm Proteins; D018336:Receptors, Aryl Hydrocarbon; D015534:Trans-Activators