title: Functional cyclic AMP response element in the breast cancer resistance protein (BCRP/ABCG2) promoter modulates epidermal growth factor receptor pathway- or androgen withdrawal-mediated BCRP/ABCG2 transcription in human cancer cells.
abstract: Phosphorylated cyclic-AMP (cAMP) response element binding protein (p-CREB) is a downstream effector of a variety of important signaling pathways. We investigated whether the human BCRP promoter contains a functional cAMP response element (CRE). 8Br-cAMP, a cAMP analogue, increased the activity of a BCRP promoter reporter construct and BCRP mRNA in human carcinoma cells. Epidermal growth factor receptor (EGFR) pathway activation also led to an increase in p-CREB and in BCRP promoter reporter activity via two major downstream EGFR signaling pathways: the phosphotidylinositol-3-kinase (PI3K)/AKT pathway and the mitogen-activated protein kinase (MAPK) pathway. EGF treatment increased the phosphorylation of EGFR, AKT, ERK and CREB, while simultaneously enhancing BCRP mRNA and functional protein expression. EGF-stimulated CREB phosphorylation and BCRP induction were diminished by inhibition of EGFR, PI3K/AKT or RAS/MAPK signaling. CREB silencing using RNA interference reduced basal levels of BCRP mRNA and diminished the induction of BCRP by EGF. Chromatin immunoprecipitation assays confirmed that a putative CRE site on the BCRP promoter bound p-CREB by a point mutation of the CRE site abolished EGF-induced stimulation of BCRP promoter reporter activity. Furthermore, the CREB co-activator, cAMP-regulated transcriptional co-activator (CRTC2), is involved in CREB-mediated BCRP transcription: androgen depletion of LNCaP human prostate cancer cells increased both CREB phosphorylation and CRTC2 nuclear translocation, and enhanced BCRP expression. Silencing CREB or CRTC2 reduced basal BCRP expression and BCRP induction under androgen-depletion conditions. This novel CRE site plays a central role in mediating BCRP gene expression in several human cancer cell lines following activation of multiple cancer-relevant signaling pathways.
authors.affiliation: Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Xie
authors.affiliation: Department of Membrane Transport and Biopharmaceutics, School of Pharmaceutical Sciences, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
authors.forename: Takeo
authors.initials: T
authors.lastname: Nakanishi
authors.affiliation: Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
authors.forename: Karthika
authors.initials: K
authors.lastname: Natarajan
authors.affiliation: Schnaper Summer Internship Program, University of Maryland Greenebaum Cancer Center, USA.
authors.forename: Lowell
authors.initials: L
authors.lastname: Safren
authors.affiliation: Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Department of Pathology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
authors.forename: Anne W
authors.initials: AW
authors.lastname: Hamburger
authors.affiliation: Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Department of Pathology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Baltimore VA Medical Center, Baltimore, MD 21201, USA.
authors.forename: Arif
authors.initials: A
authors.lastname: Hussain
authors.affiliation: Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Department of Pathology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Baltimore VA Medical Center, Baltimore, MD 21201, USA; Department of Pharmacology and Experimental Therapeutics, University of Maryland School of Medicine, Baltimore, MD 21201, USA. Electronic address: dross@som.umaryland.edu.
authors.forename: Douglas D
authors.initials: DD
authors.lastname: Ross
mesh_terms: D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D000728:Androgens / Q000378:metabolism; D001943:Breast Neoplasms / Q000235:genetics / Q000473:pathology; D045744:Cell Line, Tumor; D000242:Cyclic AMP / Q000235:genetics*; D017362:Cyclic AMP Response Element-Binding Protein / Q000037:antagonists & inhibitors / Q000235:genetics*; D066246:ErbB Receptors / Q000096:biosynthesis / Q000235:genetics*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D009363:Neoplasm Proteins / Q000235:genetics*; D010051:Ovarian Neoplasms / Q000235:genetics / Q000473:pathology; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D011471:Prostatic Neoplasms / Q000235:genetics / Q000473:pathology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D000728:Androgens; C493245:CRTC2 protein, human; D017362:Cyclic AMP Response Element-Binding Protein; D009363:Neoplasm Proteins; D014157:Transcription Factors; D000242:Cyclic AMP; C512478:EGFR protein, human; D066246:ErbB Receptors
keywords: Breast cancer; Breast cancer resistance protein (BCRP)/ABCG2; CREB; Ovarian cancer; Promoter; Prostate cancer