p53 mutations in C57BL/6J murine thymic lymphomas induced by gamma-irradiation and N-methylnitrosourea.
Genomic DNA from thymus tissue obtained from 47 C57BL/6J animals treated with the DNA alkylating agent N-methylnitrosourea or gamma-irradiation were screened for the presence of p53 mutations by using the single strand conformation polymorphism assay. Mutations were detected in 13% (4 of 30) of primary thymic lymphomas but none of 17 early stage lymphomas. The frequency of p53 mutations was the same in tumors induced by N-methylnitrosourea (2 of 15) or by gamma-irradiation (2 of 15). Mutations occurred in the highly conserved regions of the p53 gene in exons 5, 7, and 8. G:C to A:T transitions were commonly observed. One of 4 of the tumors analyzed contained two p53 mutations in exons 7 and 8. A previous study of the same tumors showed that ras mutations occurred with high frequency (greater than 50%) (E. W. Newcomb et al., Cancer Res., 48:5514-5521, 1988). Our data suggest that p53 mutations do not play a major role in carcinogen-induced thymic lymphomas studied here.
Brathwaite
O
O
New York University, New York.
Bayona
W
W
Newcomb
E W
EW
D000818:Animals; D005260:Female; D005720:Gamma Rays; D016158:Genes, p53; D011905:Genes, ras; D008223:Lymphoma / Q000209:etiology / Q000235:genetics*; D008770:Methylnitrosourea; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation; D013953:Thymus Neoplasms / Q000209:etiology / Q000235:genetics*; D014314:Trisomy
D008770:Methylnitrosourea