title: Expression of the Bcl-3 proto-oncogene suppresses p53 activation.
abstract: While Bcl-3 expression in cancer was originally thought to be limited to B-cell lymphomas with a 14;19 chromosomal translocation, more recent evidence indicates that expression of this presumptive oncoprotein is significantly more widespread in cancer. However, an oncogenic role for Bcl-3 has not been clearly identified. Experiments presented here indicate that Bcl-3 is inducible by DNA damage and is required for the induction of Hdm2 gene expression and the suppression of persistent p53 activity. Furthermore, constitutive expression of Bcl-3 suppresses DNA damage-induced p53 activation and inhibits p53-induced apoptosis through a mechanism that is at least partly dependent on the up-regulation of Hdm2. The results provide insight into a mechanism whereby altered expression of Bcl-3 leads to tumorigenic potential. Since Bcl-3 is required for germinal center formation, these results suggest functional similarities with the unrelated Bcl-6 oncoprotein in suppressing potential p53-dependent cell cycle arrest and apoptosis in response to somatic hypermutation and class switch recombination.
authors.affiliation: Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599, USA.
authors.forename: David
authors.initials: D
authors.lastname: Kashatus
authors.forename: Patricia
authors.initials: P
authors.lastname: Cogswell
authors.forename: Albert S
authors.initials: AS
authors.lastname: Baldwin
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D000081242:B-Cell Lymphoma 3 Protein; D002453:Cell Cycle / Q000187:drug effects; D004249:DNA Damage / Q000187:drug effects; D004622:Embryo, Mammalian / Q000201:enzymology / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D005786:Gene Expression Regulation; D018095:Germ-Line Mutation; D018858:Germinal Center / Q000378:metabolism; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors / Q000378:metabolism; D051736:Proto-Oncogene Proteins c-mdm2 / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D011995:Recombination, Genetic; D014157:Transcription Factors; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D051017:Apoptosis Regulatory Proteins; D000081242:B-Cell Lymphoma 3 Protein; C438378:BBC3 protein, human; C000631344:BCL3 protein, human; C000631345:Bcl3 protein, mouse; C000715470:MAS1 protein, human; D016328:NF-kappa B; C498702:PMAIP1 protein, human; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D051736:Proto-Oncogene Proteins c-mdm2