Gill R D, Cussac C, Souhami R L, Laval F
Unité 347, Institute National de la Santé et de la Richerche Médicale, Le Kremlin-Bicêtre, France.
Cancer Res. 1996 Aug 15;56(16):3721-4.
Thiotepa (N,N',N'-triethylenethiophosphoramide) is an alkylating agent used in cancer chemotherapy. A reaction pathway by which thiotepa alkylates purified DNA involves hydrolysis to aziridine, which forms N7-aminoethyl guanine and aminoethyl adenine. These lesions are repaired in Escherichia coli by the formamidopyrimidine-DNA glycosylase (Fpg) protein. To determine whether such lesions are formed by thiotepa in mammalian cells, we have overexpressed the E. coli Fpg protein in Chinese hamster ovary cells. The transfected cells were more resistant to the lethal and mutagenic effects of thiotepa than the parental cells. The number of replication-blocking lesions formed by thiotepa, measured by quantitative PCR analysis, was lower in the transfected cells. These results show that expression of the Fpg protein increases the cell resistance to thiotepa and suggest that this compound produces ring-opened guanines, which are involved in its cytotoxic action.
噻替派（N，N'，N'-三亚乙基硫代磷酰胺）是一种用于癌症化疗的烷化剂。噻替派使纯化的DNA烷基化的反应途径涉及水解生成氮丙啶，后者形成N7-氨乙基鸟嘌呤和氨乙基腺嘌呤。在大肠杆菌中，这些损伤由甲酰胺嘧啶-DNA糖基化酶（Fpg）蛋白修复。为了确定哺乳动物细胞中噻替派是否会形成此类损伤，我们在中国仓鼠卵巢细胞中过表达了大肠杆菌Fpg蛋白。与亲本细胞相比，转染细胞对噻替派的致死和诱变作用更具抗性。通过定量PCR分析测定，噻替派形成的复制阻断损伤数量在转染细胞中较低。这些结果表明，Fpg蛋白的表达增加了细胞对噻替派的抗性，并表明该化合物产生了开环鸟嘌呤，这与其细胞毒性作用有关。
