title: Ultraviolet B radiation-induced skin cancer in mice defective in the Xpc, Trp53, and Apex (HAP1) genes: genotype-specific effects on cancer predisposition and pathology of tumors.
abstract: Mutations in nucleotide excision repair (NER) genes in humans result in the UV-induced skin cancer-prone disease xeroderma pigmentosum (XP). Mouse models that mimic XP have provided an informative experimental system with which to study DNA repair, as well as the molecular pathology of UV radiation-induced skin cancer. We reported previously that mice defective in the Xpc gene (Xpc-/-) are highly predisposed to UVB radiation-induced skin cancer and that the appearance of skin cancer is more rapid in Xpc Trp53 double mutants. Extended studies now demonstrate an increased predisposition to UVB radiation-induced skin cancers in Xpc heterozygous mice compared with normal mice. We also show that Xpc Trp53 double heterozygous mutants are more predisposed to skin cancer than Trp53 single heterozygous mice. No mutations were detected in the cDNA of the remaining Xpc allele, suggesting that haploinsufficiency of the Xpc gene may be operating and is a risk factor for UVB radiation-induced skin cancer in mice. Skin tumors from Xpc-/- mice were exclusively well or moderately well-differentiated squamous cell carcinomas. In Xpc+/+ and Xpc+/- mice, many of the squamous cell carcinomas were less well differentiated. We also documented previously increased predisposition to UV radiation-induced skin cancers in Xpc-/- Apex+/- mice. Here we show the absence of mutations in the cDNA of the remaining Apex allele, a further suggestive indication of haploinsufficiency and its resulting predisposition to skin cancer. The Trp53 and Apex heterozygous conditions altered the skin tumor spectrum to more poorly differentiated forms in all Xpc genotypes.
authors.affiliation: Department of Pathology, University of Texas Southwestern Medical Center, Dallas 75235, USA.
authors.forename: D L
authors.initials: DL
authors.lastname: Cheo
authors.forename: L B
authors.initials: LB
authors.lastname: Meira
authors.forename: D K
authors.initials: DK
authors.lastname: Burns
authors.forename: A M
authors.initials: AM
authors.lastname: Reis
authors.forename: T
authors.initials: T
authors.lastname: Issac
authors.forename: E C
authors.initials: EC
authors.lastname: Friedberg
mesh_terms: D000818:Animals; D019757:Carbon-Oxygen Lyases / Q000235:genetics; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D004268:DNA-Binding Proteins / Q000235:genetics; D005796:Genes / Q000235:genetics*; D020022:Genetic Predisposition to Disease / Q000235:genetics; D005838:Genotype; D006579:Heterozygote; D006720:Homozygote; D051379:Mice; D008817:Mice, Mutant Strains; D009154:Mutation; D012720:Severity of Illness Index; D012867:Skin / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D012878:Skin Neoplasms / Q000209:etiology / Q000235:genetics* / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000235:genetics; D014466:Ultraviolet Rays / Q000009:adverse effects*
chemical_list: D004268:DNA-Binding Proteins; D016159:Tumor Suppressor Protein p53; C501002:Xpc protein, mouse; D019757:Carbon-Oxygen Lyases; C486216:Apex1 protein, mouse; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase