Effects of mutant p53 expression on human 15-lipoxygenase-promoter activity and murine 12/15-lipoxygenase gene expression: evidence that 15-lipoxygenase is a mutator gene.
Human 15-lipoxygenase (h15-LO) is present on chromosome 17p13.3 in close proximity to the tumor-suppressor gene, p53. 15-LO is implicated in antiinflammation, membrane remodeling, and cancer development/metastasis. The murine BALB/c embryo fibroblast cell line, (10)1val, expresses p53 in mutant (mt) conformation when grown at 39 degrees C and in wild-type conformation when grown at 32 degrees C. Transfection of h15-LO promoter constructs (driving luciferase reporter) into (10)1val cells and into p53-deficient (10)1 cells resulted in a marked increase in h15-LO promoter activity in (10)1val cells at 39 degrees C, but not at 32 degrees C, or as compared with (10)1 cells. Transfection of h15-LO promoter deletion constructs, however, resulted in total loss of activity in both cell types at 32 degrees C and 39 degrees C. Cotransfection of (10)1 cells with h15-LO promoter (driving luciferase reporter) along with increasing levels of a mt p53 expression vector demonstrated dose-dependent capacity of mt p53 to induce 15-LO promoter activity. No effect was observed with wild-type p53. In contrast to h15-LO promoter activity, (10)1val cells had significantly lower levels of endogenous (murine) 12/15-LO (mouse analog of h15-LO) mRNA and protein when grown at 39 degrees C compared with cells grown at 32 degrees C. Our data support the hypothesis that loss of a tumor-suppressor gene (p53), or "gain-of-function activities" resulting from the expression of its mutant forms, regulates 15-LO promoter activity in man and in mouse, albeit in directionally opposite manners. The studies define a direct link between 15-LO activity and an established tumor-suppressor gene located in close chromosomal proximity.
Kelavkar
U P
UP
Renal Division and Center for Glomerulonephritis, Emory University, Atlanta, GA 30322, USA.
Badr
K F
KF
D000818:Animals; D001092:Arachidonate 12-Lipoxygenase / Q000235:genetics*; D001093:Arachidonate 15-Lipoxygenase / Q000235:genetics*; D002478:Cells, Cultured; D004622:Embryo, Mammalian; D004742:Enhancer Elements, Genetic; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D017353:Gene Deletion; D016158:Genes, p53; D006801:Humans; D008156:Luciferases / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D014158:Transcription, Genetic; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D016159:Tumor Suppressor Protein p53; D001092:Arachidonate 12-Lipoxygenase; D001093:Arachidonate 15-Lipoxygenase; D008156:Luciferases