Specific UV-induced mutation spectrum in the p53 gene of skin tumors from DNA-repair-deficient xeroderma pigmentosum patients
- Institut de Recherches Scienrtifiques sur le Cancer, Villejuif (France)
The UV component of sunlight is the major carcinogen involved in the etiology of skin cancers. The authors have studied the rare, hereditary syndrome xeroderma pigmentosum (XP), which is characterized by a very high incidence of cutaneous tumors on exposed skin at an early age, probably due to a deficiency in excision repair of UV-induced lesions. It is interesting to determine the UV mutation spectrum in XP skin tumors in order to correlate the absence of repair of specific DNA lesions and the initiation of skin tumors. The p53 gene is frequently mutated in human cancers and represents a good target for studying mutation spectra since there are >100 potential sites for phenotypic mutations. Using reverse transcription-PCR and single-strand conformation polymorphism to analyze >40 XP skin tumors (mainly basal and squamous cell carcinomas), the authors have found that 40% (17 out of 43) contained at least one point mutation on the p53 gene. All the mutations were located at dipyrimidine sites, essentially at CC sequences, which are hot spots for UV-induced DNA lesions. Sixty-one percent of these mutations were tandem CC [yields] TT mutations considered to be unique to UV-induced lesions; these mutations are not observed in internal human tumors. All the mutations, except two, must be due to translesion synthesis of unrepaired dipyrimidine lesions left on the nontranscribed strand. These results show the existence of preferential repair of UV lesions [either pyrimidine dimers or pyrimidine-pyrimidone (6-4) photoproducts] on the transcribed strand in human tissues.
- OSTI ID:
- 7181800
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America; (United States), Vol. 90:22, Issue 22; ISSN 0027-8424
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
PYRIMIDINE DIMERS
EXCISION REPAIR
XERODERMA PIGMENTOSUM
DNA REPAIR
GENE MUTATIONS
GENETIC RADIATION EFFECTS
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
CONGENITAL DISEASES
DISEASES
GENETIC EFFECTS
HEREDITARY DISEASES
MUTATIONS
RADIATION EFFECTS
REPAIR
SKIN DISEASES
560120* - Radiation Effects on Biochemicals
Cells
& Tissue Culture
550400 - Genetics