Induction of 12-lipoxygenase expression by transforming growth factor-alpha in human epidermoid carcinoma A431 cells.
Transforming growth factor-alpha (TGF-alpha) increased the expression of 12-lipoxygenase activity in a time-dependent manner in human epidermoid carcinoma A431 cells. The increase of 12-lipoxygenase activity was accompanied by an increase in 12-lipoxygenase mRNA. The effect of TGF-alpha on the promoter activation of 12-lipoxygenase gene was analyzed by using the luciferase fusion vectors. A dose-dependent effect of TGF-alpha on the reporter activity was observed, which paralleled with its effect on enzyme activity. Transient transfection with a series of 5'-deleted constructs showed that the 5'-flanking region spanning from -224 to -100 bp from translation starting site played an important role for TGF-alpha response. Site-directed mutagenesis and gel mobility shift assay indicated that two Sp1 binding sequences residing at -158 to -150 bp and 123 to -114 bp were responsible for the TGF-alpha in activation of human 12-lipoxygenase gene transcription. Expression of Sp1, but not Sp3, stimulated the promoter activity of 12-lipoxygenase in SL2 cells, indicating that the binding of Sp1 with Sp1 binding sequences played a significant role in the regulation of 12-lipoxygenase gene.
Chen
L C
LC
Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
Chen
B K
BK
Liu
Y W
YW
Chang
W C
WC
D001092:Arachidonate 12-Lipoxygenase / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002294:Carcinoma, Squamous Cell / Q000201:enzymology* / Q000473:pathology; D004247:DNA; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic; D016329:Sp1 Transcription Factor / Q000378:metabolism; D016211:Transforming Growth Factor alpha / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D016329:Sp1 Transcription Factor; D016211:Transforming Growth Factor alpha; D004247:DNA; D001092:Arachidonate 12-Lipoxygenase