title: IKK-i/IKKepsilon controls constitutive, cancer cell-associated NF-kappaB activity via regulation of Ser-536 p65/RelA phosphorylation.
abstract: Nuclear factor kappaB (NF-kappaB) has been studied extensively as an inducible transcriptional regulator of the immune and inflammatory response. NF-kappaB activation downstream of lipopolysaccharide or cytokine stimulation is controlled by the IkappaB kinase complex, which contains IKKalpha and IKKbeta. Significantly, the constitutive activity of NF-kappaB has been implicated as an important aspect of many cancer cells, but mechanisms associated with this activity are poorly understood. An inducible kinase, IKK-i/IKKepsilon, related to the catalytic forms of the IkappaB kinase, has been studied as an anti-viral, innate immune regulator through its ability to control the activity of the transcription factors IRF-3 and IRF-7. Here, we demonstrate that IKK-i/IKKepsilon is expressed in a number of cancer cells and is involved in regulating NF-kappaB activity through its ability to control basal/constitutive, but not cytokine-induced, p65/RelA phosphorylation at Ser-536, a modification proposed to contribute to the transactivation function of NF-kappaB. Knockdown of IKK-i/IKKepsilon or expression of a S536A mutant form of p65 suppresses HeLa cell proliferation. The data indicate a role for IKK-i/IKKepsilon in controlling proliferation of certain cancer cells through regulation of constitutive NF-kappaB activity.
authors.affiliation: Lineberger Comprehensive Cancer Center, Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
authors.forename: Mazhar
authors.initials: M
authors.lastname: Adli
authors.forename: Albert S
authors.initials: AS
authors.lastname: Baldwin
mesh_terms: D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015972:Gene Expression Regulation, Neoplastic; D006367:HeLa Cells; D006801:Humans; D051550:I-kappa B Kinase / Q000378:metabolism / Q000502:physiology*; D007249:Inflammation; D016328:NF-kappa B / Q000378:metabolism*; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D012694:Serine / Q000737:chemistry*; D051996:Transcription Factor RelA / Q000737:chemistry*
chemical_list: D016328:NF-kappa B; C498143:RELA protein, human; D051996:Transcription Factor RelA; D012694:Serine; D051550:I-kappa B Kinase