Cohen N A, Egorin M J, Snyder S W, Ashar B, Wietharn B E, Pan S S, Ross D D, Hilton J
Division of Developmental Therapeutics, University of Maryland Cancer Center, Baltimore 21201.
Cancer Res. 1991 Aug 15;51(16):4360-6.
The antineoplastic agents N,N',N''-triethylenethiophosphoramide (thioTEPA) and N,N',N''-triethylenephosphoramide (TEPA) were studied for their interaction with the DNA of L1210 cells in the presence and absence of rat hepatic microsomes and NADPH. Alkaline elution was used to study 3 types of DNA lesions. When L1210 cells were incubated with thioTEPA alone, or with thioTEPA in the presence of microsomes and NADPH, no single-strand breaks were detected. However, incubation of L1210 cells for 2 h with thioTEPA, at concentrations greater than or equal to 100 microM, caused a dose-dependent increase in interstrand cross-linking that reached a maximum by 2 h after drug exposure. In the presence of rat hepatic microsomes and NADPH, this cross-linking was eliminated, but a different DNA lesion, alkali-labile sites, was produced. These alkali-labile sites were partially reparable with maximum repair achieved by 2 h after removal of drug. ThioTEPA was greater than 85% consumed by the microsomal incubation conditions employed, and TEPA was the only product of the microsomal metabolism of thioTEPA. Alkaline elution studies of L1210 cells that had been incubated with TEPA, alone or in the presence of microsomes and NADPH, demonstrated an elution pattern identical to that produced by thioTEPA in the presence of microsomes and NADPH. Lymphoblastoid cell lines derived from patients with Fanconi's anemia were far more sensitive to thioTEPA and mechlorethamine hydrochloride than were lymphoblasts derived from normal humans, but this hypersensitivity was not noted with TEPA or bleomycin. This is consistent with the known hypersensitivity of cells from patients with Fanconi's anemia to agents that produce interstrand cross-links and with the alkaline elution studies described above. In contrast, lymphoblastoid cell lines derived from patients with ataxia telangiectasia were no more sensitive to thioTEPA than were lymphoblasts derived from normal humans but were far more sensitive to bleomycin. One of these cell lines proved hypersensitive to TEPA, whereas the other was no more sensitive to TEPA than were lymphoblasts from normal humans. Our data imply that thioTEPA produces interstrand cross-links but that TEPA, the primary metabolite of thioTEPA, produces DNA lesions that are alkali labile.
对抗肿瘤药物N，N'，N''-三乙烯硫代磷酰胺（噻替派）和N，N'，N''-三乙烯磷酰胺（TEPA）在有无大鼠肝微粒体及NADPH存在的情况下与L1210细胞DNA的相互作用进行了研究。采用碱性洗脱法研究3种类型的DNA损伤。当L1210细胞单独与噻替派孵育，或在微粒体和NADPH存在的情况下与噻替派孵育时，未检测到单链断裂。然而，当L1210细胞与浓度大于或等于100μM的噻替派孵育2小时时，会导致链间交联呈剂量依赖性增加，在药物暴露后2小时达到最大值。在大鼠肝微粒体和NADPH存在的情况下，这种交联被消除，但产生了另一种DNA损伤，即碱不稳定位点。这些碱不稳定位点部分可修复，在去除药物后2小时达到最大修复程度。所用的微粒体孵育条件消耗了超过85%的噻替派，且TEPA是噻替派微粒体代谢的唯一产物。对单独或在微粒体和NADPH存在的情况下与TEPA孵育的L1210细胞进行碱性洗脱研究，结果显示其洗脱模式与噻替派在微粒体和NADPH存在时产生的洗脱模式相同。范可尼贫血患者来源的淋巴母细胞系对噻替派和盐酸氮芥的敏感性远高于正常人来源的淋巴母细胞，但对TEPA或博来霉素未观察到这种超敏反应。这与已知的范可尼贫血患者细胞对产生链间交联的药物的超敏反应以及上述碱性洗脱研究结果一致。相比之下，共济失调毛细血管扩张症患者来源的淋巴母细胞系对噻替派的敏感性并不高于正常人来源的淋巴母细胞，但对博来霉素更为敏感。其中一个细胞系对TEPA超敏，而另一个对TEPA的敏感性并不高于正常人来源的淋巴母细胞。我们的数据表明，噻替派产生链间交联，但噻替派的主要代谢产物TEPA产生的是碱不稳定的DNA损伤。
