title: Activation of adenosine deaminase in MCF-7 cells through IGF-estrogen receptor alpha crosstalk.
abstract: Adenosine deaminase (ADA) regulates cellular levels of adenosine and deoxyadenosine, and 17beta-estradiol (E(2)) induces ADA mRNA in MCF-7 human breast cancer cells. IGF-I also induces ADA gene expression in these cells, and induction of this response through IGF activation of estrogen receptor alpha (ERalpha) was further investigated. IGF and other polypeptide growth factors induce reporter gene expression in MCF-7 cells cotransfected with ERalpha expression plasmid and pADA211, a construct containing the -211 to +11 region of the ADA gene promoter which is required for high basal and E(2)-inducible activity. Deletion analysis of this promoter demonstrates that IGF activates ERalpha/Sp1 interactions with multiple GC-rich sites in the promoter and this response is abrogated in cells transfected with ERalpha containing mutations at Ser(118) or Ser(163). IGF induces both MAPK (mitogen-activated protein kinase) and PI3-K (phosphatidylinositol-3-kinase) phosphorylation cascades in MCF-7 cells; however, using a series of inhibitors and dominant negative constructs, our results show that induction of ADA by IGF activation of ERalpha/Sp1 is dependent on the MAPK signaling pathway.
authors.affiliation: Department of Veterinary Physiology & Pharmacology, Texas A&M University, 4466 TAMU, College Station, Texas 77843-4466, USA.
authors.forename: W
authors.initials: W
authors.lastname: Xie
authors.forename: R
authors.initials: R
authors.lastname: Duan
authors.forename: S
authors.initials: S
authors.lastname: Safe
mesh_terms: D000243:Adenosine Deaminase / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000201:enzymology* / Q000473:pathology; D017931:DNA Primers; D004789:Enzyme Activation; D047628:Estrogen Receptor alpha; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D020239:Receptor Cross-Talk; D011960:Receptors, Estrogen / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D017931:DNA Primers; D047628:Estrogen Receptor alpha; D011518:Proto-Oncogene Proteins; D011960:Receptors, Estrogen; D007334:Insulin-Like Growth Factor I; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases; D000243:Adenosine Deaminase