Antioxidants stimulate transcriptional activation of the c-fos gene by multiple pathways in human fetal lung fibroblasts (WI-38).
We have examined the effects of three structurally distinct antioxidants (N-acetylcysteine [NAC], Trolox C [a water-soluble vitamin E derivative], and nordihydroguaiaretic acid [NGA]) on the expression of the c-fos gene over a 2-hour period. Determination of cellular glutathione concentration (the primary determinant of the cellular redox state) over the same time-course verifies that all the compounds studied cause an increase in cellular reduction potential. The level of c-fos messenger RNA increased rapidly in response to micromolar concentrations of these compounds, reaching a peak in 30-60 minutes. Induction of c-fos expression by these antioxidants is at least partly due to an increase in transcription, as determined by nuclear run-on assay. Down regulation of protein kinase C (PKC) by pretreatment for 24 hours with 500 nm PMA prevents induction by subsequent stimulation with either PMA or NGA. NAC induction of c-fos is unaffected by PMA pretreatment, while Trolox C superinduced c-fos following PMA pretreatment. None of these treatments stimulated translocation of PKC-alpha from the cytosol to the membrane. These results suggest that increasing the intracellular reducing potential induces c-fos expression through multiple pathways.
Keogh
B
B
Center for Gerontological Research, Allegheny University, Philadelphia, Pennsylvania 19129, USA.
Allen
R G
RG
Tresini
M
M
Furth
J J
JJ
Cristofalo
V J
VJ
D000111:Acetylcysteine / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology*; D015152:Blotting, Northern; D002273:Carcinogens / Q000494:pharmacology; D002839:Chromans / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005333:Fetus / Q000201:enzymology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects; D016166:Free Radical Scavengers / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D008168:Lung / Q000166:cytology*; D009637:Masoprocol / Q000494:pharmacology; D009281:Naphthalenes / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D015398:Signal Transduction / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D015533:Transcriptional Activation / Q000187:drug effects*
D000975:Antioxidants; D002273:Carcinogens; D002839:Chromans; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D009281:Naphthalenes; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D009637:Masoprocol; D011493:Protein Kinase C; D005978:Glutathione; C058819:calphostin C; D013755:Tetradecanoylphorbol Acetate; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid; D000111:Acetylcysteine