Role of specificity protein transcription factors in estrogen-induced gene expression in MCF-7 breast cancer cells.
Deletion analysis of several 17beta-estradiol (E(2))-responsive genes have identified GC-rich sites that are associated with hormone-induced transactivation in MCF-7 breast cancer cells. However, the role of individual specificity proteins (Sps) in mediating hormone-induced gene expression has not been unequivocally determined. In transient transfection studies using E(2)-responsive GC-rich promoters from the E(2)F1, carbamoylphosphate synthetase/aspartate transcarbamylase/dihydroorotase (CAD), and retinoic acid receptor alpha (RAR alpha) genes, RNA interference using small inhibitory RNAs for Sp1 (iSp1), Sp3 (iSp3), and Sp4 (iSp4) decreased both basal and E(2)-induced transactivation. The contributions of individual Sp proteins to basal and E(2)-induced activity were promoter dependent. iSp1, iSp3, and iSp4 also significantly inhibited hormonal induction of E(2)F1, CAD, and RAR alpha mRNA levels; however, the enhanced inhibitory effects of the latter two small inhibitory RNAs suggest that Sp3 and Sp4 play a major role in estrogen receptor alpha/Sp-mediated gene expression in MCF-7 cells.
Khan
Shaheen
S
Department of Veterinary Physiology and Pharmacology, Texas A & M University, College Station, Texas 77843-4466, USA.
Wu
Fei
F
Liu
Shengxi
S
Wu
Qian
Q
Safe
Stephen
S
D000818:Animals; D001221:Aspartate Carbamoyltransferase / Q000235:genetics; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D019556:COS Cells; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing) / Q000235:genetics; D002522:Chlorocebus aethiops; D004080:Dihydroorotase / Q000235:genetics; D050687:E2F1 Transcription Factor / Q000378:metabolism; D047628:Estrogen Receptor alpha / Q000378:metabolism; D004967:Estrogens / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D018168:Receptors, Retinoic Acid / Q000235:genetics / Q000378:metabolism; D000072482:Retinoic Acid Receptor alpha; D051703:Sp Transcription Factors / Q000378:metabolism / Q000502:physiology*; D014018:Tissue Distribution; D014407:Tumor Cells, Cultured
C033626:CAD trifunctional enzyme; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; D047628:Estrogen Receptor alpha; D004967:Estrogens; C000607071:RARA protein, human; D018168:Receptors, Retinoic Acid; D000072482:Retinoic Acid Receptor alpha; D051703:Sp Transcription Factors; D001221:Aspartate Carbamoyltransferase; D004080:Dihydroorotase; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing)