Cigarette smoke condensate activates nuclear transcription factor-kappaB through phosphorylation and degradation of IkappaBalpha: correlation with induction of cyclooxygenase-2

Abstract

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.

Targeting Nuclear Factor-κB Activation Pathway by Thymoquinone: Role in Suppression of Antiapoptotic Gene Products and Enhancement of Apoptosis

“…Phorbol myristate acetate, okadaic acid, lipopolysaccharide, and cigarette smoke condensate are potent activators of NF-nB, but the pathways by which these agents activate NF-nB, however, differs (30)(31)(32)(33). The effect of TQ on the activation of NF-nB by these agents was examined by EMSA.…”

“…Bacteria-derived recombinant human TNF, purified to homogeneity with a specific activity of 5 Â 10 7 units/mg, was kindly provided by Genentech. Cigarette smoke condensate, prepared as previously described (30), was kindly supplied by Dr. C. Gary Gairola (University of Kentucky). Paclitaxel, doxorubicin, phorbol 12-myristate 13-acetate, okadaic acid, lipopolysaacharide, DTT, and h-actin antibody were obtained from Sigma-Aldrich.…”

γ-Tocotrienol Inhibits Nuclear Factor-κB Signaling Pathway through Inhibition of Receptor-interacting Protein and TAK1 Leading to Suppression of Antiapoptotic Gene Products and Potentiation of Apoptosis

“…Bacteria-derived recombinant human TNF, purified to homogeneity with a specific activity of 5 ϫ 10 7 units/ mg, was kindly provided by Genentech (South San Francisco, CA). Cigarette smoke condensate, prepared as described previously (33), was kindly supplied by Dr. C. G. Gairola (University of Kentucky, Lexington). Penicillin, streptomycin, Iscove's modified Dulbecco's medium, and FBS were obtained from Invitrogen.…”

Pinitol targets nuclear factor-κB activation pathway leading to inhibition of gene products associated with proliferation, apoptosis, invasion, and angiogenesis

“…Gairola (University of Kentucky; ref. 19). Penicillin, streptomycin, Iscove's modified Dulbecco's medium, and fetal bovine serum were obtained from Invitrogen.…”