Characterization of the promoter region of the human somatostatin receptor subtype 2 gene and localization of sequences required for estrogen-responsiveness.
Somatostatin receptor (sst) subtype 2 mRNA is potently regulated by 17beta-estradiol (E2) in a time and dose-dependent manner in the estrogen receptor (+) human breast cancer cell line T47D. To explore the mechanism involved in E2 regulated expression of sst2, we isolated and characterized a genomic clone containing over 5.3 kilobase pairs (kb) of the 5' flanking region of the human sst2 gene. The 5'-flanking region lacks both TATA and CCAAT boxes. Primer extension and RNAase protection analysis revealed the existence of two transcriptional start sites, located within an initiator-like sequence, 85 and 82 bp upstream of the translational initiation methionine. The 5.3-kb 5'-flanking region was an active promoter in T47D cells but was inactive in MDA MB 435s cells, a human breast cancer cell line that does not express sst2. Deletion analysis identified both positive and negative regulatory elements within the 5.3-kb fragment. Furthermore, transcriptional regulation by E2 was mediated by a distal 1.5-kb fragment located 3.8 kb from the transcriptional start sites. Determining the precise ERE will provide important insights into the complex regulation of sst2 expression in normal and neoplastic tissue.
Xu
Y
Y
Department of Medicine, SUNY at Stony Brook, NY 11794, USA.
Berelowitz
M
M
Bruno
J F
JF
D001483:Base Sequence; D001943:Breast Neoplasms; D003001:Cloning, Molecular; D004958:Estradiol / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics*; D017481:Receptors, Somatostatin / Q000235:genetics; D011993:Recombinant Fusion Proteins; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D017384:Sequence Deletion; D014158:Transcription, Genetic / Q000235:genetics; D014407:Tumor Cells, Cultured
D017481:Receptors, Somatostatin; D011993:Recombinant Fusion Proteins; D004958:Estradiol; C093733:somatostatin receptor 2