The mitogenic response to tumor necrosis factor alpha requires c-Jun/AP-1.
In the present study, we addressed the role of the c-jun proto-oncogene in the mitogenic response of human fibroblasts and primary acute myelogenous leukemia blasts to tumor necrosis factor alpha (TNF-alpha). Our data indicate that TNF-alpha treatment of these cells is associated with transcriptional activation of c-jun, resulting in accumulation of c-jun mRNA and protein expression. In order to elucidate the role of c-Jun/AP-1 in TNF-mediated growth stimulation, the antisense (AS) technique was used. Uptake studies of oligonucleotides were performed with fibroblasts, demonstrating that incorporation of oligomers was maximal at 4 h. Oligodeoxynucleotides remained stable in these cells for up to 24 h. Treatment of fibroblasts with the AS oligonucleotide resulted in intracellular duplex formation followed by an efficient translation blockade of c-Jun/AP-1. In contrast, sense (S) and nonsense (NS) oligodeoxynucleotides failed to form intracellular duplexes and also did not interfere with translation of c-Jun/AP-1, suggesting specific elimination of c-Jun/AP-1 by the AS oligomer. Fibroblasts cultured in the presence of the AS oligonucleotide but not those cultured in the presence of the S or NS oligonucleotide failed to respond proliferatively to TNF-alpha. These findings could be confirmed by experiments with primary acute myelogenous leukemia blasts, which also demonstrated that TNF-induced growth stimulation required c-Jun/AP-1 function. Taken together, our results indicate that activation of c-Jun/AP-1 plays a pivotal role in the signaling cascade initiated by TNF, which leads to a proliferative response of its target cells.
Brach
M A
MA
Max Delbrück Center for Molecular Medicine, Berlin, Germany.
Gruss
H J
HJ
Sott
C
C
Herrmann
F
F
D001483:Base Sequence; D015152:Blotting, Northern; D002455:Cell Division / Q000187:drug effects / Q000235:genetics; D002460:Cell Line; D004247:DNA; D015870:Gene Expression; D006801:Humans; D007700:Kinetics; D015470:Leukemia, Myeloid, Acute; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D000090063:Proto-Oncogene Mas; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics* / Q000378:metabolism; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D016755:Proto-Oncogene Proteins c-jun; D014409:Tumor Necrosis Factor-alpha; D004247:DNA