Hesterberg T W, Boreiko C J, Maness S C, Iglehart J D, Mangum J B, Everitt J I
Department of Genetic Toxicology, Chemical Industry Institute of Toxicology, Research Triangle Park, NC 27709.
Carcinogenesis. 1988 Mar;9(3):467-72. doi: 10.1093/carcin/9.3.467.
Extrapolation from rodent genotoxicity data to humans is complicated by variables such as interspecies differences in carcinogen metabolism and DNA repair. A xenograft system containing human bronchial epithelial cells was used to assess the induction of unscheduled DNA synthesis (UDS) by carcinogens and to compare the response with that of rat tracheal epithelium. Cells from human bronchus were grown in explant culture, inoculated into de-epithelialized rat tracheas and implanted subcutaneously into nude mice. Within six weeks, a differentiated mucociliary epithelium lined the xenografted tracheas. Fresh rat tracheas and human xenografts were cut into rings and incubated in media containing [3H]thymidine and either the direct-acting carcinogen, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG, 3-1000 microM), or a carcinogen requiring metabolic activation, 4-nitroquinoline-1-oxide (4-NQO, 3-100 microM). Tissues were then fixed, sectioned, processed for autoradiography and the number of nuclear grains (NG) determined for 100 epithelial cells lining the trachea in each section. A time- and concentration-dependent increase in NG was observed in both human xenografts and rat tracheas after treatment with MNNG or 4-NQO, indicating induction of UDS by these agents. The UDS response to MNNG in the human xenografts was similar to that observed in the rat tracheas, whereas the response to 4-NQO was greater in rat tracheas. These studies indicate that the human xenograft system should have applications for the study of carcinogen-induced damage in normal bronchial epithelial cells.
由于存在种间致癌物代谢和DNA修复差异等变量，从啮齿动物基因毒性数据推断人类情况变得复杂。使用包含人支气管上皮细胞的异种移植系统来评估致癌物对非预定DNA合成（UDS）的诱导作用，并将其反应与大鼠气管上皮的反应进行比较。将来自人支气管的细胞在植块培养中生长，接种到去上皮的大鼠气管中，并皮下植入裸鼠体内。六周内，异种移植的气管内衬有分化的黏液纤毛上皮。将新鲜的大鼠气管和人异种移植物切成环，在含有[3H]胸腺嘧啶核苷以及直接作用致癌物N-甲基-N'-硝基-N-亚硝基胍（MNNG，3 - 1000微摩尔）或需要代谢活化的致癌物4-硝基喹啉-1-氧化物（4-NQO，3 - 100微摩尔）的培养基中孵育。然后将组织固定、切片、进行放射自显影处理，并确定每个切片中气管内衬的100个上皮细胞的核颗粒数（NG）。在用MNNG或4-NQO处理后，在人异种移植物和大鼠气管中均观察到NG呈时间和浓度依赖性增加，表明这些试剂诱导了UDS。人异种移植物对MNNG的UDS反应与在大鼠气管中观察到的相似，而对4-NQO的反应在大鼠气管中更大。这些研究表明，人异种移植系统在研究致癌物诱导的正常支气管上皮细胞损伤方面应具有应用价值。
