Huber B E, Brown N A
Cancer Res. 1983 Nov;43(11):5544-51.
The many embryonic and developmental features associated with tumor promotion have prompted us to investigate the effects of a series of phorbol esters and related diterpene tumor promoters on mammalian embryogenesis. A culture system which supports the normal development of 10.4 day organogenesis-phase rat conceptuses was utilized. In this system, 12-O-tetradecanoylphorbol-13-acetate (TPA), a potent Stage I and II promoter, disrupted the morphology and function of the embryonic visceral yolk sac (dose required to affect 50% of conceptuses, 18 nM). The effect was characterized by an abnormal, progressive separation of the two cellular layers of the yolk sac, but cellular differentiation appeared to be uninterrupted. Parallel log dose-response lines for this effect were produced by phorbol-12,13-dibenzoate (dose required to affect 50% of conceptuses, 200 nM) and phorbol-12,13-diacetate (dose required to affect 50% of conceptuses, 300 nM) which are consistent with structure-activity relationships for other promotional actions of these compounds. In addition, the weak Stage I promoter, 4-O-methyl-12-O-tetradecanoylphorbol-13-acetate, produced identical effects but was 1400 times less potent than was TPA, while mezerein, a potent Stage II promoter, was as potent as was TPA. These observations support the hypothesis that embryonic cells may be differentially sensitive to early- and late-stage promoters. Ethylphenylpropiolate, a nonpromoting hyperplastic agent in mouse skin, had no effect on yolk sac morphology or function at its maximum solubility (1.85 mM). Yolk sac disruption by TPA was potentiated by heat inactivation (56 degrees, 30 min) or 0.45-micron filtration of the culture medium. A more advanced stage of yolk sac development was less sensitive to TPA disruption since 11.4 day conceptuses, which were cultured for 30 hr, developed identical lesions, but TPA was at least 5-fold less potent. Thus, the tumor promoter-induced lesions of the rat yolk sac have some features consistent with late-stage tumor promotion and do not appear to be associated with general toxicity, hyperplasia, or alterations in cellular differentiation. We postulate that rat conceptuses maintained in vitro may provide an important model system for the study of the proposed mechanisms involved in chemical tumor promotion.
与肿瘤促进相关的众多胚胎和发育特征促使我们研究一系列佛波酯及相关二萜类肿瘤促进剂对哺乳动物胚胎发育的影响。我们采用了一种能支持10.4天器官发生期大鼠胚胎正常发育的培养系统。在该系统中，强效的I期和II期促进剂12 - O - 十四烷酰佛波醇 - 13 - 乙酸酯（TPA）破坏了胚胎内脏卵黄囊的形态和功能（影响50%胚胎所需剂量为18 nM）。其作用表现为卵黄囊的两层细胞异常且逐渐分离，但细胞分化似乎未受干扰。佛波醇 - 12,13 - 二苯甲酸酯（影响50%胚胎所需剂量为200 nM）和佛波醇 - 12,13 - 二乙酸酯（影响50%胚胎所需剂量为300 nM）产生了与此作用平行的对数剂量反应线，这与这些化合物其他促进作用的构效关系一致。此外，弱I期促进剂4 - O - 甲基 - 12 - O - 十四烷酰佛波醇 - 13 - 乙酸酯产生了相同的作用，但效力比TPA低1400倍，而强效II期促进剂美泽瑞因与TPA效力相当。这些观察结果支持了胚胎细胞可能对早期和晚期促进剂有不同敏感性的假说。乙基苯基丙炔酸酯是小鼠皮肤中的一种非促进性增生剂，在其最大溶解度（1.85 mM）时对卵黄囊形态或功能无影响。TPA对卵黄囊的破坏作用因培养基热灭活（56摄氏度，30分钟）或0.45微米过滤而增强。卵黄囊发育的更晚期阶段对TPA破坏作用的敏感性较低，因为培养30小时的11.4天胚胎出现了相同的损伤，但TPA的效力至少低5倍。因此，肿瘤促进剂诱导的大鼠卵黄囊损伤具有一些与晚期肿瘤促进一致的特征，似乎与一般毒性、增生或细胞分化改变无关。我们推测体外培养的大鼠胚胎可能为研究化学性肿瘤促进所涉及的机制提供一个重要的模型系统。
