EP2 and EP4 receptors regulate aromatase expression in human adipocytes and breast cancer cells. Evidence of a BRCA1 and p300 exchange.
Cytochrome P450 aromatase (aromatase), a product of the CYP19 gene, catalyzes the synthesis of estrogens from androgens. Because aromatase-dependent estrogen biosynthesis has been linked to hormone-dependent breast carcinogenesis, it is important to elucidate the mechanisms that regulate CYP19 gene expression. The main objective of this study was to identify the receptors (EP) for prostaglandin E(2) (PGE(2)) that mediate the induction of CYP19 transcription in human adipocytes and breast cancer cells. Treatment with PGE(2) induced aromatase, an effect that was mimicked by either EP(2) or EP(4) agonists. Antagonists of EP(2) or EP(4) or small interference RNA-mediated down-regulation of these receptors suppressed PGE(2)-mediated induction of aromatase. PGE(2) via EP(2) and EP(4) stimulated the cAMP-->protein kinase A pathway resulting in enhanced interaction between P-CREB, p300, and the aromatase promoter I.3/II. Overexpressing a mutant form of p300 that lacks histone acetyltransferase activity suppressed PGE(2)-mediated induction of aromatase promoter activity. PGE(2) via EP(2) and EP(4) also caused a reduction in both the amounts of BRCA1 and the interaction between BRCA1 and the aromatase promoter I.3/II. Activation of the aromatase promoter by PGE(2) was suppressed by overexpressing wild-type BRCA1. Silencing of EP(2) or EP(4) also blocked PGE(2)-mediated induction of the progesterone receptor, a prototypic estrogen-response gene. In a mouse model, overexpressing COX-2 in the mammary gland, a known inducer of PGE(2) synthesis, led to increased aromatase mRNA and activity and reduced amounts of BRCA1; these effects were reversed by knocking out EP(2). Taken together, these results suggest that PGE(2) via EP(2) and EP(4) activates the cAMP-->PKA-->CREB pathway leading to enhanced CYP19 transcription and increased aromatase activity. Reciprocal changes in the interaction between BRCA1, p300, and the aromatase promoter I.3/II contributed to the inductive effects of PGE(2).
Subbaramaiah
Kotha
K
Department of Medicine, Weill Cornell Medical College, New York, New York 10065. Electronic address: ksubba@med.cornell.edu.
Hudis
Clifford
C
Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York 10065.
Chang
Sung-Hee
SH
Center for Vascular Biology, Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut 06030-3501.
Hla
Timothy
T
Center for Vascular Biology, Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut 06030-3501.
Dannenberg
Andrew J
AJ
Department of Medicine, Weill Cornell Medical College, New York, New York 10065.
D017667:Adipocytes / Q000201:enzymology* / Q000378:metabolism; D000818:Animals; D001141:Aromatase / Q000096:biosynthesis* / Q000235:genetics*; D019313:BRCA1 Protein / Q000235:genetics*; D001943:Breast Neoplasms / Q000201:enzymology*; D045744:Cell Line, Tumor; D015232:Dinoprostone / Q000378:metabolism; D050881:E1A-Associated p300 Protein / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D015674:Mammary Neoplasms, Animal / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D018078:Receptors, Prostaglandin E / Q000378:metabolism*; D058307:Receptors, Prostaglandin E, EP2 Subtype; D058309:Receptors, Prostaglandin E, EP4 Subtype
D019313:BRCA1 Protein; C492913:BRCA1 protein, human; C545644:PTGER2 protein, human; C545650:PTGER4 protein, human; C545645:Ptger2 protein, mouse; C545651:Ptger4 protein, mouse; D018078:Receptors, Prostaglandin E; D058307:Receptors, Prostaglandin E, EP2 Subtype; D058309:Receptors, Prostaglandin E, EP4 Subtype; D001141:Aromatase; D050881:E1A-Associated p300 Protein; C494360:EP300 protein, human; D015232:Dinoprostone