Relationship between constitutive nuclear factor-kappaB (NF-kappaB) and inhibitor kappaB-alpha (IkappaB-alpha) in an interferon-alpha-sensitive human Burkitt lymphoma cell line.
The human Burkitt lymphoma Daudi cell line expresses constitutively active nuclear factor kappaB (NF-kappaB) in the nucleus in spite of high levels of inhibitor kappaB-alpha (IkappaB-alpha) in the cytoplasm. The antiproliferative response of these cells to interferon-alpha (IFN-alpha) correlated with the inhibition of the constitutive NF-kappaB activity by the cytokine. The present study shows that IFN-alpha caused an increase in p53 level, inhibited cell proliferation by [(3)H]thymidine incorporation, and stimulated cytotoxicity and apoptosis by PARP-cleavage in the Daudi cells. In order to study the relationship between the constitutively active NF-kappaB and IkappaB-alpha, a dominant negative mutant IkappaB-alpha (IkappaB-alphaDN), lacking the N-terminal 36 amino acids required for the activation of NF-kappaB by tumor necrosis factor-alpha (TNF-alpha), was expressed in the Daudi cells. The expression of IkappaB-alphaDN protein did not inhibit the constitutive NF-kappaB activity, but it inhibited cell proliferation, antiproliferative response to IFN-alpha, and phosphorylated mitogen activated protein kinase (p-MAPK) level. Thus, our results suggest that constitutive NF-kappaB activity in the human Burkitt lymphoma Daudi cells is maintained by a mechanism independent of IkappaB-alpha degradation, and that the IkappaB-alpha is involved in the proliferation of these cells, possibly through the MAP kinase pathway. Therefore, in addition to IFN-alpha treatment, both NF-kappaB and IkappaB-alpha may be used as drug targets for inhibiting cell proliferation in the lymphomas.
Molecular Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi-110067, India. pcrath@mail.jnu.ac.in
Pramod C
PC
Rath
D017209:Apoptosis / Q000502:physiology; D015153:Blotting, Western; D002051:Burkitt Lymphoma / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D024161:Collagen Type XI / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism*; D016898:Interferon-alpha / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D013778:Tetrazolium Salts; D013844:Thiazoles; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
C499319:COL11A2 protein, human; D024161:Collagen Type XI; D020672:I-kappa B Proteins; D016898:Interferon-alpha; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D013778:Tetrazolium Salts; D013844:Thiazoles; D016159:Tumor Suppressor Protein p53; D000072000:NF-KappaB Inhibitor alpha; D020928:Mitogen-Activated Protein Kinases; C022616:thiazolyl blue