Pitot H C, Campbell H A, Maronpot R, Bawa N, Rizvi T A, Xu Y H, Sargent L, Dragan Y, Pyron M
McArdle Laboratory for Cancer Research Medical School, University of Wisconsin, Madison 53706.
Toxicol Pathol. 1989;17(4 Pt 1):594-611; discussion 611-2. doi: 10.1177/0192623389017004105.
Critical parameters in the quantitation of altered hepatic foci (AHF) developing during multistage hepatocarcinogenesis in the rat include: 1) the enumeration of AHF induced by test agents as well as those AHF occurring spontaneously in livers of untreated animals; 2) the volume percentage or fraction of the liver occupied by all AHF as a reflection of the total number of altered cells within the liver and the degree of tumor promotion which has occurred; and 3) the phenotype of individual AHF as determined by multiple markers with serial sections. These parameters, especially the number of AHF, should be corrected by the presence of spontaneous AHF which increase with the age of the animal, more so in males than females. While accurate estimation of the background level of spontaneous AHF can be important in demonstrating that a carcinogenic agent does not possess the ability to increase the numbers of AHF above the background level, a better method to distinguish the effectiveness and relative potencies of agents as initiators or promoters is reviewed. The relative effectiveness of four different markers--gamma-glutamyltranspeptidase (GGT), a placental form of glutathione S-transferase (GST), canalicular ATPase, and glucose 6-phosphatase (G6Pase)--was described for the chemicals C.I. Solvent Yellow 14 and chlorendic acid as promoting agents in males and females. C.I. Solvent Yellow 14 is a more effective promoting agent in females than males, and AHF exhibit extremely low numbers scored by GGT. On the other hand, the numbers of AHF present in livers of male rats promoted by this agent are more than twice those seen in livers of female animals, possibly owing to the effectiveness of this agent as an initiator in the male but not the female. Very few AHF, especially in the male, are scored by GGT during chlorendic acid promotion. The distribution of phenotypes with these markers also differs in the spontaneous AHF appearing in the livers of animals fed 0.05% phenobarbital on either a crude NIH-07 or AIN-76 purified diet. Such studies emphasize the extreme dependence of the promoting stage of hepatocarcinogenesis on environmental factors of sex, diet, and the molecular nature of the promoting agent itself. The hallmark of the final stage of progression in the development of hepatocellular carcinomas is aneuploidy, which may be reflected by phenotypic heterogeneity within individual AHF, termed foci-in-foci. The implications of such quantitative analyses during hepatocarcinogenesis induced by specific agents in relation to the specific action of the agent at one or more of the stages of hepatocarcinogenesis are discussed.
大鼠多阶段肝癌发生过程中，定量检测肝灶性病变（AHF）的关键参数包括：1）受试物诱导产生的AHF数量以及未处理动物肝脏中自发出现的AHF数量；2）所有AHF占据肝脏的体积百分比或比例，以此反映肝脏内细胞改变的总数以及已发生的肿瘤促进程度；3）通过连续切片使用多种标志物确定单个AHF的表型。这些参数，尤其是AHF的数量，应根据自发AHF的存在情况进行校正，自发AHF会随着动物年龄的增长而增加，雄性动物增加得比雌性动物更多。虽然准确估计自发AHF的背景水平对于证明致癌剂不具备将AHF数量增加到背景水平以上的能力可能很重要，但本文综述了一种更好的方法来区分作为启动剂或促进剂的试剂的有效性和相对效力。描述了四种不同标志物——γ-谷氨酰转肽酶（GGT）、胎盘型谷胱甘肽S-转移酶（GST）、胆小管ATP酶和葡萄糖6-磷酸酶（G6Pase）——对于化学物质C.I.溶剂黄14和氯菌酸作为雄性和雌性促进剂的相对有效性。C.I.溶剂黄14在雌性动物中作为促进剂比在雄性动物中更有效，并且AHF经GGT评分的数量极低。另一方面，用该试剂促进的雄性大鼠肝脏中存在的AHF数量是雌性动物肝脏中所见数量的两倍多，这可能是由于该试剂在雄性动物而非雌性动物中作为启动剂的有效性。在氯菌酸促进过程中，经GGT评分的AHF很少，尤其是在雄性动物中。在用粗制NIH-07或AIN-76纯化饲料喂养的动物肝脏中出现的自发AHF中，这些标志物的表型分布也有所不同。此类研究强调了肝癌发生促进阶段对性别、饮食等环境因素以及促进剂本身分子性质的极度依赖性。肝细胞癌发展进程最后阶段的标志是染色体数目异常，这可能通过单个AHF内的表型异质性反映出来，即灶中灶。本文讨论了在特定试剂诱导的肝癌发生过程中进行此类定量分析与该试剂在肝癌发生一个或多个阶段的特定作用之间的关系。
