Brathwaite O, Bayona W, Newcomb E W
New York University, New York.
Cancer Res. 1992 Jul 1;52(13):3791-5.
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.
从47只经DNA烷化剂N-甲基亚硝基脲处理或γ射线辐照的C57BL/6J动物的胸腺组织中提取基因组DNA，采用单链构象多态性分析法筛查p53突变的存在情况。在13%（30例中的4例）的原发性胸腺淋巴瘤中检测到突变，但17例早期淋巴瘤中均未检测到。N-甲基亚硝基脲诱导的肿瘤（15例中的2例）和γ射线辐照诱导的肿瘤（15例中的2例）中p53突变频率相同。突变发生在p53基因外显子5、7和8的高度保守区域。常见G:C到A:T的转换。分析的4例肿瘤中有1例在第7和第8外显子中含有两个p53突变。对同一肿瘤的先前研究表明，ras突变发生频率很高（大于50%）（E.W.纽科姆等人，《癌症研究》，48:5514 - 5521，1988）。我们的数据表明，p53突变在此处研究的致癌物诱导的胸腺淋巴瘤中不发挥主要作用。
