This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Yagi, T. Articles by Takebe, H. Search for Related Content PubMed PubMed Citation Articles by Yagi, T. Articles by Takebe, H.

Analysis of Point Mutations in an Ultraviolet-irradiated Shuttle Vector Plasmid Propagated in Cells from Japanese Xeroderma Pigmentosum Patients in Complementation Groups A and F¹

Department of Experimental Radiology, Faculty of Medicine, Kyoto University, Yoshida-konoe-cho, Sakyo-ku, Kyoto 606, Japan [T. Y., J. T-M., M. S., H. T.], and Laboratory of Molecular Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892 [K. H. K.]

To assess the contribution to mutagenesis by human DNA repair defects, a UV-treated shuttle vector plasmid, pZ189, was passed through fibroblasts derived from Japanese xeroderma pigmentosum (XP) patients in two different DNA repair complementation groups (A and F). Patients with XP have clinical and cellular UV hypersensitivity, increased frequency of skin cancer, and defects in DNA repair. The XP DNA repair defects represented by complementation groups A (XP-A) and F (XP-F) are more common in Japan than in Europe or the United States. In comparison to results with DNA repair-proficient human cells (WI38-VA13), UV-treated pZ189 passed through the XP-A [XP2OS(SV)] or XP-F [XP2YO(SV)] cells showed fewer surviving plasmids (XP-A less than XP-F) and a higher frequency of mutated plasmids (XP-A greater than XP-F). Base sequence analysis of more than 200 mutated plasmids showed the major type of base substitution mutation to be the G:C A:T transition with all three cell lines. The XP-A and XP-F cells revealed a higher frequency of G:C A:T transitions and a lower frequency of transversions among plasmids with single or tandem mutations and a lower frequency of plasmids with multiple point mutations compared to the normal line. The spectrum of mutations in pZ189 with the XP-A cells was similar to that with the XP-F cells. Seventy-six to 91% of the single base substitution mutations occurred at G:C base pairs in which the 5'-neighboring base of the cytosine was thymine or cytosine. These studies indicate that the DNA repair defects in Japanese XP patients in complementation groups A and F result in different frequencies of plasmid survival and mutagenesis but in similar types of mutagenic abnormalities despite marked differences in clinical features. These results, together with comparable studies from United States patients in XP complementation groups A and D, suggest that G:C A:T somatic mutations may be important in the generation of human skin cancer by UV radiation.

¹ This research was supported by Grants-in-aid from the Ministry of Education, Science and Culture.

² To whom requests for reprints should be addressed.

Received 12/13/90. Accepted 4/ 2/91.