Ward J M, Rice J M, Creasia D, Lynch P, Riggs C
Carcinogenesis. 1983 Aug;4(8):1021-9. doi: 10.1093/carcin/4.8.1021.
Potentially preneoplastic hepatocellular hyperplastic foci and hepatocellular neoplasms were studied in weanling male B6C3F1 mice that received a single i.p. injection (80 mg/kg) of diethylnitrosamine (DEN) at 4 weeks of age, followed by oral administration of phenobarbital (PB) or di(2-ethylhexyl)-phthalate (DEHP) that began 2 weeks after DEN injection and continued for up to 6 months. PB was administered in drinking water at 500 p.p.m. and DEHP in the feed at 3000, 6000 or 12 000 p.p.m. Groups of mice were sacrificed at 2, 4 and 6 months after DEN exposure; formalin-fixed liver samples were evaluated histologically. Hepatocellular neoplasms and foci of hyperplasia were quantified with the aid of an image analysis computer. Few foci were seen at 2, 4 or 6 months in mice exposed to DEN, PB or DEHP alone, while numerous foci and neoplasms were seen in mice given DEHP or PB after DEN. Area-perimeter measurements for each hepatocellular focus or neoplasm transection revealed that foci and neoplasms in PB-exposed mice increased both in size (area and volume) and in number throughout the study. In DEHP-exposed mice the pattern of response was different in that the numbers of foci did not increase between 4 and 6 months, but the foci increased in mean diameter and volume throughout the experiment. Foci and tumors appeared earlier in mice given higher dietary levels of DEHP than in those given lower doses. By the end of the study the number of foci per unit volume of liver was similar in mice given any dose of DEHP, but their volume was dose-related. Hepatocellular foci and neoplasms in PB-exposed mice were composed predominantly of eosinophilic hepatocytes, while in DEHP-exposed mice, basophilic foci and neoplasms predominated; the latter were more malignant in appearance than neoplasms in PB-exposed mice. At 6 months, the neoplasms in high dose DEHP-exposed mice were significantly larger than those in PB exposed mice. Histochemistry, however, revealed similarities between lesions in mice exposed to PB or DEHP. PB given continuously for 6 months revealed no initiating activity of DEHP given once by gavage and followed by PB in drinking water. Both morphology and biology of hepatocellular foci and neoplasms, which develop in mice after a single exposure to a carcinogen with initiating activity, thus depend, in part, on the subsequent promoting agent. More than one process of tumor promotion, as characterized by a specific sequence of morphologic and biochemical changes, is possible for the mouse hepatocyte.
对断乳雄性B6C3F1小鼠的潜在癌前肝细胞增生灶和肝细胞肿瘤进行了研究。这些小鼠在4周龄时经腹腔注射一次二乙基亚硝胺（DEN，80mg/kg），然后在DEN注射2周后开始口服苯巴比妥（PB）或邻苯二甲酸二（2-乙基己基）酯（DEHP），持续6个月。PB以500ppm的浓度添加到饮用水中，DEHP以3000、6000或12000ppm的浓度添加到饲料中。在DEN暴露后2、4和6个月处死小鼠组；对福尔马林固定的肝脏样本进行组织学评估。借助图像分析计算机对肝细胞肿瘤和增生灶进行定量。单独暴露于DEN、PB或DEHP的小鼠在2、4或6个月时可见少量病灶，而在DEN后给予DEHP或PB的小鼠中可见大量病灶和肿瘤。对每个肝细胞病灶或肿瘤横切面的面积-周长测量显示，在整个研究过程中，暴露于PB的小鼠中的病灶和肿瘤在大小（面积和体积）和数量上均增加。在暴露于DEHP的小鼠中，反应模式不同，即病灶数量在4至6个月之间没有增加，但在整个实验过程中病灶的平均直径和体积增加。给予较高饮食水平DEHP的小鼠比给予较低剂量的小鼠更早出现病灶和肿瘤。到研究结束时，给予任何剂量DEHP的小鼠每单位肝脏体积中的病灶数量相似，但其体积与剂量相关。暴露于PB的小鼠中的肝细胞病灶和肿瘤主要由嗜酸性肝细胞组成，而在暴露于DEHP的小鼠中，嗜碱性病灶和肿瘤占主导；后者在外观上比暴露于PB的小鼠中的肿瘤更具恶性。在6个月时，高剂量DEHP暴露小鼠中的肿瘤明显大于PB暴露小鼠中的肿瘤。然而，组织化学显示暴露于PB或DEHP小鼠中的病变之间存在相似性。连续给予6个月的PB未显示一次灌胃给予DEHP并随后在饮用水中给予PB的启动活性。因此，单次暴露于具有启动活性的致癌物后在小鼠中发生的肝细胞病灶和肿瘤的形态和生物学特性部分取决于随后的促癌剂。对于小鼠肝细胞，可能存在不止一种以特定形态和生化变化序列为特征的肿瘤促进过程。
