Regulation of spontaneous and TNF/IFN-induced IL-6 expression in two human ovarian-carcinoma cell lines.
Autocrine and paracrine production of interleukin-6 (IL-6) is considered to be involved in the ongoing proliferation of ovarian-cancer cells. In view of the variability in IL-6 expression between various ovarian-cancer cells, we questioned whether differences in IL-6-gene regulation might be observed in ovarian tumor cells with and without IL-6 expression. The CAOV-3 cell line spontaneously secreted IL-6, which was enhanced by tumor necrosis factor-alpha (877 +/- 89 vs. 8,452 +/- 1,762 pg/ml, x +/- sd, p < 0.01). The electrophoretic mobility shift assay (EMSA) demonstrated that basic IL-6 expression was associated with DNA binding of activator protein-1 (AP-1) and nuclear factor IL-6 (NF-IL6). Nuclear factor kappa-B (NF-KB), which consisted mainly of p65-NF-KB was induced in response to TNF-alpha stimulation. A2780 cells did not express IL-6, either spontaneously or after stimulation with TNF-alpha. EMSAs, showed spontaneous AP-1 but no NF-IL6 or NF-KB DNA binding. TNF-alpha stimulation enhanced AP-1 and induced NF-KB but no NF-IL6 DNA binding in these cells. NF-IL6 protein, however, was detected in nuclear extracts of these cells by Western blotting. In contrast, IL-6-promoter transfection studies showed no difference in promoter activation between CAOV-3 and A2780. This study reveals that differential IL-6-gene expression observed in ovarian-cancer cell lines is independent of NF-IL6 activation.
Asschert
J G
JG
Department of Hematology, University Hospital, Groningen, The Netherlands.
Vellenga
E
E
Ruiters
M H
MH
de Vries
E G
EG
D004273:DNA, Neoplasm / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000235:genetics / Q000473:pathology*; D011401:Promoter Regions, Genetic; D011485:Protein Binding / Q000187:drug effects; D012333:RNA, Messenger / Q000096:biosynthesis; D012334:RNA, Neoplasm / Q000096:biosynthesis; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D017422:Sequence Analysis, DNA; D013268:Stimulation, Chemical; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D004273:DNA, Neoplasm; D015850:Interleukin-6; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma