Schoket B, Hewer A, Grover P L, Phillips D H
Chester Beatty Laboratories, Institute of Cancer Research, London, UK.
Carcinogenesis. 1988 Jul;9(7):1253-8. doi: 10.1093/carcin/9.7.1253.
In order to assess the DNA damaging ability of complex carcinogenic mixtures, male Parkes mice were treated topically with solutions of (i) pharmaceutical coal-tar, (ii) creosote, a blend of coal-tar fractions or (iii) bitumen, a product of oil-refining. DNA was isolated from the treated skin and analysed by 32P-post-labelling. A band of radioactivity was obtained on polyethyleneimine--cellulose TLC indicating the formation of DNA adducts by a large number of different chemical compounds present in these fossil fuel products. The chromatographic properties of the adducts were broadly characteristic of those formed by polycyclic aromatic hydrocarbons. The levels of DNA binding were approximately 0.4 fmol total adducts/micrograms DNA 24 h after treatment for coal-tar and creosote and 0.09 fmol/micrograms DNA for bitumen treatment. The persistence of adducts in mouse skin following a single dose of either coal-tar or creosote was found to exhibit a phase of rapid removal, in which one half to two thirds of the initial levels of adducts, detected at 24 h after treatment, were removed by 7 days followed by a second phase in which one half to two thirds of the remainder was removed in the succeeding 25 days. When mice were treated topically with multiple carcinogenic doses of coal-tar, creosote or bitumen for up to 5 weeks, a steady accumulation of adducts was seen in skin DNA during the course of the treatment, approaching a steady-state level towards the end of the treatment period in some instances. A similar accumulation of adducts was also evident in lung DNA, the levels being approximately half those attained in skin. The results demonstrate the application of 32P-post-labelling to the detection of DNA adducts formed in vivo by complex carcinogenic mixtures of the type to which humans are exposed.
为了评估复杂致癌混合物的DNA损伤能力，对雄性帕克斯小鼠进行局部处理，分别使用以下溶液：(i) 药用煤焦油；(ii) 杂酚油，一种煤焦油馏分的混合物；(iii) 沥青，一种炼油产品。从处理过的皮肤中分离DNA，并通过32P后标记法进行分析。在聚乙烯亚胺 - 纤维素薄层层析（TLC）上获得了一条放射性条带，表明这些化石燃料产品中存在的大量不同化合物形成了DNA加合物。加合物的色谱特性与多环芳烃形成的加合物大致相同。处理24小时后，煤焦油和杂酚油处理组的DNA结合水平约为0.4 fmol总加合物/微克DNA，沥青处理组为0.09 fmol/微克DNA。发现单次给予煤焦油或杂酚油后，小鼠皮肤中加合物的持久性呈现出一个快速清除阶段，在这个阶段，处理后24小时检测到的初始加合物水平的一半至三分之二在7天内被清除，随后是第二个阶段，在接下来的25天内，剩余加合物的一半至三分之二被清除。当小鼠局部接受多次致癌剂量的煤焦油、杂酚油或沥青处理长达5周时，在处理过程中皮肤DNA中加合物出现稳定积累，在某些情况下，接近处理期末达到稳态水平。肺DNA中也明显出现类似的加合物积累，其水平约为皮肤中加合物水平的一半。结果证明了32P后标记法在检测人类接触的这类复杂致癌混合物在体内形成的DNA加合物中的应用。
