title: Regulation of FasL by NF-kappaB and AP-1 in Fas-dependent thymineless death of human colon carcinoma cells.
abstract: Cell death due to thymine (dThd) deficiency, associated with the cytotoxic action of 5-fluorouracil in colon cancer, is regulated in thymidylate synthase-deficient (TS(-)) human colon carcinoma cells via the Fas (CD95, APO-1) death receptor. This was demonstrated by inhibiting the loss in clonogenicity of TS(-) cells by anti-FasL and in enhanced survival of TS(-) clones selected for resistance to Fas-mediated apoptosis, following dThd deprivation. During thymineless stress in TS(-) cells, Fas ligand (FasL) is expressed, and its promoter (hFasLPr) is activated. Transactivation of hFasLPr, dependent upon dThd deficiency, was inhibited following mutation of the binding sites for NF-kappaB or AP-1 and by preventing NF-kappaB or AP-1 activation, which inhibited expression of FasL and enhanced clonogenic survival in stable transformants expressing IkappaBalphaM or DN-MEKK, respectively. These results demonstrate the crucial roles for NF-kappaB and AP-1 in the regulation of FasL in Fas-mediated thymineless death of colon carcinoma cells.
authors.affiliation: Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.
authors.forename: F G
authors.initials: FG
authors.lastname: Harwood
authors.forename: S
authors.initials: S
authors.lastname: Kasibhatla
authors.forename: I
authors.initials: I
authors.lastname: Petak
authors.forename: R
authors.initials: R
authors.lastname: Vernes
authors.forename: D R
authors.initials: DR
authors.lastname: Green
authors.forename: J A
authors.initials: JA
authors.lastname: Houghton
mesh_terms: D017209:Apoptosis; D002470:Cell Survival; D002999:Clone Cells; D003110:Colonic Neoplasms; D004268:DNA-Binding Proteins / Q000378:metabolism; D053222:Fas Ligand Protein; D006801:Humans; D020672:I-kappa B Proteins; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000378:metabolism; D013940:Thymidylate Synthase / Q000172:deficiency; D013941:Thymine / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D015533:Transcriptional Activation; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D004268:DNA-Binding Proteins; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D020672:I-kappa B Proteins; D008562:Membrane Glycoproteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D011994:Recombinant Proteins; D018808:Transcription Factor AP-1; D000072000:NF-KappaB Inhibitor alpha; D013940:Thymidylate Synthase; D013941:Thymine