Role of nucleotide excision repair deficiency in intestinal tumorigenesis in multiple intestinal neoplasia ( Min) mice

• Published in: Mutation research Vol. 611; no. 1; pp. 71 - 82
• Main Authors: Steffensen, Inger-Lise, Schut, Herman A.J., Nesland, Jahn M., Tanaka, Kiyoji, Alexander, Jan
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 10.12.2006; Elsevier
• Subjects: Animals; Biological and medical sciences; Body Weight - drug effects; Colon - drug effects; Colon - metabolism; Colon - pathology; Dermatology; DNA adducts; DNA Adducts - analysis; DNA Adducts - metabolism; DNA Repair - drug effects; DNA Repair - genetics; DNA Repair - physiology; Dose-Response Relationship, Drug; Female; Fundamental and applied biological sciences. Psychology; Genetics of eukaryotes. Biological and molecular evolution; Hereditary diseases of the skin. Congenital diseases of the skin. Haemangioma of the skin, of mucosae and of soft tissue; Imidazoles - analysis; Imidazoles - metabolism; Imidazoles - toxicity; Intestinal Neoplasms - chemically induced; Intestinal Neoplasms - genetics; Intestinal Neoplasms - mortality; Intestinal tumorigenesis; Intestines - drug effects; Intestines - metabolism; Intestines - pathology; Male; Medical sciences; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Min mouse; Nucleotide excision repair; PhIP; Survival Analysis; Survival Rate; Toxicology; Xeroderma pigmentosum group A; Xeroderma Pigmentosum Group A Protein - genetics; Xeroderma Pigmentosum Group A Protein - metabolism; Xpa−/− mouse; Intestinal tumorigenesis; Xpa −/− mouse; Nucleotide excision repair; Min mouse; PhIP; DNA adducts; Xeroderma pigmentosum group A; Photosensitivity; Skin disease; Pigmentation disorder; Excision; Rodentia; Xeroderma pigmentosum; Genetic disease; Photodermatosis; Vertebrata; Toxicology; Mammalia; Mouse; Nucleotide; Genetics; Repair; Molecular adduct; Xpa-/- mouse
• ISSN: 1383-5718; 0027-5107; 1879-3592
• DOI: 10.1016/j.mrgentox.2006.07.004

Mice deficient in the Xeroderma pigmentosum group A ( Xpa) gene are defective in nucleotide excision repair (NER) and highly susceptible to skin carcinogenesis after dermal exposure to UV light or chemicals. Min (multiple intestinal neoplasia) mice, heterozygous for a germline nonsense mutation in the tumor suppressor gene adenomatous polyposis coli ( Apc), develop intestinal tumors spontaneously and show additional intestinal tumors after exposure to the food mutagen 2-amino-1-methyl-6-phenylimidazo[4,5- b]pyridine (PhIP). In this study, we investigated the impact of loss of XPA function on PhIP-induced intestinal tumorigenesis in F1 offspring of Min/+ ( Apc +/−) mice crossed with Xpa gene-deficient mice. Apc +/− mice lacking both alleles of Xpa had higher susceptibility towards toxicity of PhIP, higher levels of PhIP–DNA adducts in the middle and distal small intestines, as well as in liver, and a higher number of small intestinal tumors at 11 weeks, compared with Apc +/− mice with one or two intact Xpa alleles. Localization of tumors was not affected, being highest in middle and distal small intestines in all genotypes. At 11 weeks of age, the number of spontaneous intestinal tumors was not significantly increased by homozygous loss of Xpa, but untreated Apc +/−/ Xpa −/− mice had significantly shorter life-spans than their XPA-proficient littermates. Heterozygous loss of Xpa did not affect any of the measured end points. In conclusion, the Xpa gene and the NER pathway are involved in repair of bulky PhIP–DNA adducts in the intestines and the liver, and most probably of DNA lesions leading to spontaneous intestinal tumors. These results confirm a role of the NER pathway also in protection against cancer in internal organs, additional to its well-known importance in protection against skin cancer. An effect of Apc +/− on adduct levels, additional to that of Xpa −/−, indicates that the truncated APC protein may affect a repair pathway other than NER.