Involvement of reactive oxygen intermediates in the induction of c-jun gene transcription by ionizing radiation.
Previous work has demonstrated that the cellular response to ionizing radiation includes transcriptional activation of the c-jun gene. The signaling events responsible for this response, however, remain unclear. The present studies have examined the effects of ionizing radiation on c-jun expression in a variant of HL-60 cells, designated HL-525, which is deficient in protein kinase C (PKC)-mediated signal transduction. The results demonstrate that these cells express low levels of PKC alpha and PKC beta transcripts and exhibit an attenuated induction of c-jun expression following treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA). In contrast, HL-525 cells respond to ionizing radiation with an increase in c-jun mRNA which is more pronounced than that in wild-type HL-60 cells. These cells similarly respond to ionizing radiation with increased expression of the jun-B, jun-D, c-fos, and fos-B genes. Nuclear run-on assays demonstrate that X-ray-induced c-jun expression in HL-525 cells is regulated by increases in the rate of c-jun gene transcription. Moreover, mRNA stability studies in irradiated HL-525 cells demonstrate that the half-life of c-jun transcripts is prolonged compared to that in wild-type cells. Studies with N-acetyl-L-cysteine (NAC), an antioxidant, suggest that X-ray-induced transcriptional activation of the c-jun gene is mediated at least in part through the formation of reactive oxygen intermediates (ROIs). In this context, H2O2 also induced c-jun expression in HL-525 cells, and this effect was inhibited by NAC.(ABSTRACT TRUNCATED AT 250 WORDS)
Datta
R
R
Laboratory of Clinical Pharmacology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115.
Hallahan
D E
DE
Kharbanda
S M
SM
Rubin
E
E
Sherman
M L
ML
Huberman
E
E
Weichselbaum
R R
RR
Kufe
D W
DW
D002467:Cell Nucleus / Q000502:physiology; D002588:Cesium Radioisotopes; D002999:Clone Cells; D003609:Dactinomycin / Q000494:pharmacology; D005720:Gamma Rays; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000528:radiation effects; D016762:Genes, fos / Q000528:radiation effects; D016758:Genes, jun / Q000528:radiation effects*; D006801:Humans; D007527:Isoenzymes / Q000235:genetics* / Q000378:metabolism; D015473:Leukemia, Promyelocytic, Acute; D011493:Protein Kinase C / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D012334:RNA, Neoplasm / Q000235:genetics / Q000302:isolation & purification; D015183:Restriction Mapping; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic / Q000528:radiation effects*
D002588:Cesium Radioisotopes; D007527:Isoenzymes; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D003609:Dactinomycin; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate