title: DDB2 gene disruption leads to skin tumors and resistance to apoptosis after exposure to ultraviolet light but not a chemical carcinogen.
abstract: Mutations in the human DDB2 gene give rise to xeroderma pigmentosum group E, a disease characterized by increased skin tumorigenesis in response to UV-irradiation. Cell strains derived from xeroderma pigmentosum group E individuals also have enhanced resistance to UV-irradiation due to decreased p53-mediated apoptosis. To further address the precise function(s) of DDB2 and the consequence of non-naturally occurring DDB2 mutations, we generated mice with a disruption of the gene. The mice exhibited significantly enhanced skin carcinogenesis in response to UV-irradiation, and cells from the DDB2(-/-) mice were abnormally resistant to killing by the radiation and had diminished UV-induced, p53-mediated apoptosis. Notably, the cancer-prone phenotype and the resistance to cellular killing were not observed after exposure to the chemical carcinogen, 7,12-dimethylbenz[a]anthracene (DMBA), to which mice carrying defective nucleotide excision repair genes respond with enhanced tumors and cell killing. Although cells from heterozygous DDB2(+/-) mice appeared normal, these mice had enhanced skin carcinogenesis after UV-irradiation, so that XP-E heterozygotes might be at risk for carcinogenesis. In sum, these results demonstrate that DDB2 is well conserved between humans and mice and functions as a tumor suppressor, at least in part, by controlling p53-mediated apoptosis after UV-irradiation.
authors.affiliation: Divisions of Biochemistry and Molecular Biology, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3202, USA. toshiki@uclink4@berkeley.edu
authors.forename: Toshiki
authors.initials: T
authors.lastname: Itoh
authors.forename: Dragana
authors.initials: D
authors.lastname: Cado
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Kamide
authors.forename: Stuart
authors.initials: S
authors.lastname: Linn
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000528:radiation effects*; D002273:Carcinogens / Q000494:pharmacology*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D002471:Cell Transformation, Neoplastic / Q000187:drug effects / Q000473:pathology / Q000528:radiation effects; D004268:DNA-Binding Proteins / Q000172:deficiency* / Q000235:genetics; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D017353:Gene Deletion; D051379:Mice; D012878:Skin Neoplasms / Q000235:genetics* / Q000473:pathology*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D002273:Carcinogens; C117669:DDB2 protein, human; D004268:DNA-Binding Proteins; D016159:Tumor Suppressor Protein p53; D015127:9,10-Dimethyl-1,2-benzanthracene; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases