Inhibitors of both nuclear factor-kappaB and activator protein-1 activation block the neoplastic transformation response.
Cross-coupling of active protein-1 (AP-1) and nuclear factor (NF)-kappaB has been reported. In the present study, we investigated the possibility that both of these two transcription factors might contribute to the process of tumor promoter-induced transformation. To establish a stable reporter cell system, two reporter genes were stably transfected into a JB6 mouse tumor promotion-sensitive (P+) cell line: a luciferase reporter controlled by a collagenase AP-1 sequence and a chloramphenicol acetyltransferase reporter controlled by an interleukin 6 NF-kappaB sequence. This double-reporter cell line maintained the phenotype of tumor promotion sensitivity and was able to report basal or induced AP-1 and NF-kappaB transactivation. The cytokine tumor promoter tumor necrosis factor (TNF)-alpha transactivated NF-kappaB and AP-1 for both DNA binding and transcriptional activity. Pyrrolidine dithiocarbamate, an antioxidant that acts as an NF-kappaB inhibitor, efficiently inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA) or TNF-alpha induced NF-kappaB as well as AP-1 transactivation and cell transformation, suggesting dependency of transformation on both transcription factors. The AP-1 transrepressing-retinoid SR11302 transrepressed AP-1 and cell transformation when these were TPA induced but not when TNF-alpha induced, indicating different signaling pathways for TNF-alpha and TPA. Supershift electrophoresis mobility shift assay revealed that Jun B and c-Jun were absent from the AP-1/DNA complex following TNF-alpha but present following TPA treatment. Together, these results suggest that both AP-1 and NF-kappaB activation may be required for transformation whether induced by TPA or by TNF, and the differential sensitivity of TPA and TNF-alpha-induced transformation to inhibition by a retinoid might be explained by differences in the composition of the DNA-bound AP-1 complexes.
Li
J J
JJ
Laboratory of Biochemical Physiology, National Cancer Institute, Frederick Cancer Research and Development Center, NIH, Maryland 21702, USA. lij@ncifcrf.gov
Westergaard
C
C
Ghosh
P
P
Colburn
N H
NH
D000818:Animals; D016588:Anticarcinogenic Agents / Q000494:pharmacology; D002273:Carcinogens / Q000037:antagonists & inhibitors / Q000494:pharmacology; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D002478:Cells, Cultured / Q000187:drug effects; D004247:DNA / Q000378:metabolism; D017930:Genes, Reporter; D051379:Mice; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D011759:Pyrrolidines / Q000494:pharmacology; D012176:Retinoids / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000037:antagonists & inhibitors / Q000494:pharmacology; D013859:Thiocarbamates / Q000494:pharmacology; D013997:Time Factors; D018808:Transcription Factor AP-1 / Q000037:antagonists & inhibitors / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects*; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000494:pharmacology
D016588:Anticarcinogenic Agents; D002273:Carcinogens; D016328:NF-kappa B; D011759:Pyrrolidines; D012176:Retinoids; C106195:SR 11302; D013859:Thiocarbamates; D018808:Transcription Factor AP-1; D014409:Tumor Necrosis Factor-alpha; C020972:pyrrolidine dithiocarbamic acid; D004247:DNA; D013755:Tetradecanoylphorbol Acetate