Wei S J, Chang R L, Wong C Q, Bhachech N, Cui X X, Hennig E, Yagi H, Sayer J M, Jerina D M, Preston B D
Department of Chemical Biology and Pharmacognosy, College of Pharmacy, Rutgers, State University of New Jersey, Piscataway 08854.
Proc Natl Acad Sci U S A. 1991 Dec 15;88(24):11227-30. doi: 10.1073/pnas.88.24.11227.
Mutations in the coding region of the hypoxanthine (guanine) phosphoribosyltransferase (HPRT) gene of Chinese hamster V-79 cells were examined after exposure of the cells to a high cytotoxic dose (0.48 microM; 35% survival) and a low noncytotoxic dose (0.04 microM; 100% survival) of the ultimate carcinogen (+)-7R,8S-dihydroxy-9S,10R-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene [(+)-BPDE]. Independent 8-azaguanine-resistant colonies were isolated and cDNAs were prepared by reverse transcription. The coding region of the cDNA of the HPRT gene was amplified by the polymerase chain reaction and sequenced. An examination of the DNA base sequence changes induced by different doses of (+)-BPDE demonstrated that the high dose of (+)-BPDE caused base substitution mutations almost exclusively at G.C base pairs whereas the low dose of (+)-BPDE caused mutations at both G.C and A.T base pairs. Thus, use of a low dose of (+)-BPDE allowed the detection of mutations (at A.T base pairs) that were not readily observed with a high dose of (+)-BPDE. The data also suggest that the low dose of (+)-BPDE may have caused a different profile of base substitutions at G.C base pairs and exon deletions than the high dose. The results indicate dose-dependent differences in the profile of mutations for an ultimate carcinogen.
将中国仓鼠V - 79细胞暴露于终致癌物（+）-7R,8S - 二羟基 - 9S,10R - 环氧 - 7,8,9,10 - 四氢苯并[a]芘[（+）-BPDE]的高细胞毒性剂量（0.48 microM；存活率35%）和低非细胞毒性剂量（0.04 microM；存活率100%）后，检测次黄嘌呤（鸟嘌呤）磷酸核糖基转移酶（HPRT）基因编码区的突变情况。分离出独立的8 - 氮杂鸟嘌呤抗性菌落，并通过逆转录制备cDNA。通过聚合酶链反应扩增HPRT基因cDNA的编码区并进行测序。对不同剂量的（+）-BPDE诱导的DNA碱基序列变化进行检测表明，高剂量的（+）-BPDE几乎仅在G.C碱基对处引起碱基替代突变，而低剂量的（+）-BPDE在G.C和A.T碱基对处均引起突变。因此，使用低剂量的（+）-BPDE能够检测到高剂量的（+）-BPDE不易观察到的突变（在A.T碱基对处）。数据还表明，低剂量的（+）-BPDE可能在G.C碱基对处引起了与高剂量不同的碱基替代谱以及外显子缺失。结果表明终致癌物的突变谱存在剂量依赖性差异。
