Cigarette smoke condensate activates nuclear transcription factor-kappaB through phosphorylation and degradation of IkappaB(alpha): correlation with induction of cyclooxygenase-2.
Cigarette smoke (CS) contains several carcinogens known to initiate and promote tumorigenesis and metastasis. Because various genes that mediate carcinogenesis and tumorigenesis are regulated by nuclear factor-kappaB (NF-kappaB), we postulated that the effects of CS must be mediated through activation of this transcription factor. Therefore, in the present report we investigated whether cigarette smoke condensate (CSC) activates NF-kappaB, and whether the pathway employed for activation is similar to that of TNF, one of the potent activators of NF-kappaB. Our results show that the treatment of human histiocytic lymphoma U-937 cells with CSC activated NF-kappaB in a dose- and time-dependent manner. The kinetics of NF-kappaB activation by CSC was comparable with that of TNF. CSC-induced NF-kappaB activation was not cell type-specific, as it also activated NF-kappaB in T cells (Jurkat), lung cells (H1299), and head and neck squamous cell lines (1483 and 14B). Activation of NF-kappaB by CSC correlated with time-dependent degradation of IkappaB(alpha), an inhibitor of NF-kappaB. Further studies revealed that CSC induced phosphorylation of the serine residue at position 32 in IkappaB(alpha). In vitro immunocomplex kinase assays showed that CSC activated IkappaB(alpha) kinase (IKK). The suppression of CSC-activated NF-kappaB-dependent reporter gene expression by dominant negative form of IkappaB(alpha), TRAF2, NIK and IKK suggests a similarity to the TNF-induced pathway for NF-kappaB. CSC also induced the expression of cyclooxygenase-2, an NF-kappaB regulated gene product. Overall, our results indicate that through phosphorylation and degradation of IkappaB(alpha), CSC can activate NF-kappaB in a wide a variety of cells, and this may play a role in CS-induced carcinogenesis.
Cytokine Research Laboratory, Department of Bioimmunotherapy, Box 143, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA.
Ruby John
RJ
Anto
Asok
A
Mukhopadhyay
Shishir
S
Shishodia
C Gary
CG
Gairola
Bharat B
BB
Aggarwal
D051546:Cyclooxygenase 2; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D015870:Gene Expression; D017930:Genes, Reporter; D006367:HeLa Cells; D006801:Humans; D051550:I-kappa B Kinase; D020672:I-kappa B Proteins; D007527:Isoenzymes / Q000096:biosynthesis*; D008565:Membrane Proteins; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D010766:Phosphorylation; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D021122:Protein Subunits; D011506:Proteins / Q000378:metabolism; D012907:Smoking / Q000235:genetics / Q000378:metabolism*; D047992:TNF Receptor-Associated Factor 2; D013997:Time Factors; D014407:Tumor Cells, Cultured; D020298:U937 Cells; D000097782:NF-kappaB-Inducing Kinase
D051546:Cyclooxygenase 2; D004268:DNA-Binding Proteins; D051550:I-kappa B Kinase; D020672:I-kappa B Proteins; D007527:Isoenzymes; D008565:Membrane Proteins; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B; D011451:Prostaglandin-Endoperoxide Synthases; D017346:Protein Serine-Threonine Kinases; D021122:Protein Subunits; D011506:Proteins; D047992:TNF Receptor-Associated Factor 2; D000097782:NF-kappaB-Inducing Kinase; C000606204:NFKBIA protein, human; C496540:PTGS2 protein, human; C496559:CHUK protein, human; C496560:IKBKB protein, human; C496565:IKBKE protein, human