title: Estrogen-dependent regulation of ornithine decarboxylase in breast cancer cells through activation of nongenomic cAMP-dependent pathways.
abstract: 17beta-estradiol (E2) induces ornithine decarboxylase (ODC) activity in several E2-responsive tissues/cells, and this study investigated the mechanism of hormone-induced transactivation in MCF-7 human breast cancer cells. E2-induced reporter gene (luciferase) activity in MCF-7 cells transfected with a construct (pODC1) containing the -164 to +29 region of the human ODC gene promoter linked to bacterial luciferase. This promoter sequence contains GC-rich Sp1 binding sites, CAAT, LSF, cAMP response element (CRE), and TATA motifs. Deletion and mutational analysis of the ODC promoter showed that both CAAT and LSF sites were required for hormone-induced transactivation. Gel mobility shift and DNA footprinting assays indicated that NFYA and LSF bound the CAAT and LSF motifs, respectively, and GAL4-NFYA/GAL4-LSF chimeras were also activated by E2, 8-bromo-cAMP, and protein kinase A (PKA) expression plasmid. However, E2-induced transactivation of GAL4-NFYA and GAL4-LSF was blocked by the PKA inhibitor SQ22356 indicating that the mechanism of ODC induction by E2 involves upregulation of cAMP/PKA through nongenomic pathways of estrogen action.
authors.affiliation: Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, Texas 77843-4466, USA.
authors.forename: Chunhua
authors.initials: C
authors.lastname: Qin
authors.forename: Ismael
authors.initials: I
authors.lastname: Samudio
authors.forename: Sharon
authors.initials: S
authors.lastname: Ngwenya
authors.forename: Stephen
authors.initials: S
authors.lastname: Safe
mesh_terms: D001943:Breast Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D018983:DNA Footprinting; D024202:Electrophoretic Mobility Shift Assay; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D009154:Mutation; D009955:Ornithine Decarboxylase / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011960:Receptors, Estrogen / Q000378:metabolism; D020218:Response Elements; D017384:Sequence Deletion; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured
chemical_list: D004967:Estrogens; D011960:Receptors, Estrogen; D014157:Transcription Factors; D000242:Cyclic AMP; D008156:Luciferases; D017868:Cyclic AMP-Dependent Protein Kinases; D009955:Ornithine Decarboxylase