Regulation by estrogen through the 5'-flanking region of the transforming growth factor alpha gene.
Expression of transforming growth factor alpha (TGF alpha) mRNA and protein can be stimulated by estrogens such as 17 beta-estradiol (E2) in estrogen-responsive rodent and human breast cancer cells. To ascertain if E2 can directly regulate TGF alpha expression through the 5'-flanking region of the human TGF alpha gene, E2-responsive MCF-7 or ZR-75-1 human breast cancer cells or E2-nonresponsive MDA-MB-231 breast cancer cells were transiently transfected with a plasmid containing an 1140-base pair (bp) Sac-I fragment of the TGF alpha 5'-flanking region ligated to the chloramphenicol acetyltransferase (CAT) gene. Cells that were transfected and subsequently treated with physiological concentrations of E2 (10(-11)-10(-8) M) for 24 h exhibited a 2- to 10-fold increase in CAT activity. The E2 stimulation of CAT activity was dose-dependent with an increase first found at 10(-10) M E2. The increase in CAT activity could be detected within 24-36 h after the addition of E2. There was no significant change in CAT activity in transiently transfected MDA-MB-231 cells as mediated through the TGF alpha 5'-flanking region after E2 treatment. MCF-7 cells were also transiently transfected with different fragments of the TGF alpha 5'-flanking region ligated to the luciferase gene. In the absence of E2 treatment, no detectable luciferase activity was found.(ABSTRACT TRUNCATED AT 250 WORDS)
Saeki
T
T
Tumor Growth Factor Section, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.
Cristiano
A
A
Lynch
M J
MJ
Brattain
M
M
Kim
N
N
Normanno
N
N
Kenney
N
N
Ciardiello
F
F
Salomon
D S
DS
D000818:Animals; D001483:Base Sequence; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology; D002415:Cats / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D004273:DNA, Neoplasm / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010957:Plasmids; D011374:Progesterone / Q000494:pharmacology; D011863:Radioimmunoassay; D014162:Transfection; D016211:Transforming Growth Factor alpha / Q000235:genetics*; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism / Q000473:pathology
D004273:DNA, Neoplasm; D004967:Estrogens; D016211:Transforming Growth Factor alpha; D011374:Progesterone; D008156:Luciferases