Oesterle D, Deml E
J Cancer Res Clin Oncol. 1983;105(2):141-7. doi: 10.1007/BF00406924.
The promoting activity of the commercial PCB mixture Clophen A 50 on preneoplastic, enzyme-altered islands in rat liver was investigated. Female Sprague-Dawley rats, 3 and 6 weeks old, were pretreated with nitrosamines for island initiation. Thereafter Clophen A 50 was administered repeatedly. Island development was examined between 2 and 12 weeks. Clophen A 50 by itself initiated few enzyme-altered islands, indicating a weak carcinogenicity. In Clophen A 50-treated adult rats, the majority of nitrosamine-initiated islands persisted. Without Clophen A 50 more than 80% of the islands disappeared between 6 and 12 weeks. Moreover, PCBs caused a striking increase in island number and total area during the last 2 weeks. In weanlings, islands persisted with or without the promoting stimulus. However, treatment with Clophen A 50 caused an earlier appearance and a higher number and total area of islands. The increase in the yield of DEN-initiated islands in both age groups is suggested to be due to the promotion of initiated but dormant cells. By pretreatment with N-NM instead of DEN, a shift to larger islands was observed additionally. The data indicate that weanlings are highly susceptible to initiation and promotion and may thus provide a sensitive tool to screen for tumor initiating and promoting agents.
研究了商用多氯联苯混合物氯芬A 50对大鼠肝脏中癌前、酶改变岛的促进活性。对3周龄和6周龄的雌性斯普拉格-道利大鼠用亚硝胺进行岛启动预处理。此后反复给予氯芬A 50。在2至12周期间检查岛的发育情况。氯芬A 50自身引发的酶改变岛很少，表明其致癌性较弱。在经氯芬A 50处理的成年大鼠中，大多数亚硝胺启动的岛持续存在。在没有氯芬A 50的情况下，超过80%的岛在6至12周之间消失。此外，多氯联苯在最后2周期间使岛的数量和总面积显著增加。在断奶幼鼠中，无论有无促进刺激，岛都持续存在。然而，用氯芬A 50处理导致岛更早出现，数量和总面积更高。两个年龄组中由二乙基亚硝胺启动的岛产量增加被认为是由于对已启动但处于休眠状态的细胞的促进作用。通过用N-亚硝基甲胺而非二乙基亚硝胺进行预处理，还观察到向更大岛的转变。数据表明断奶幼鼠对启动和促进高度敏感，因此可能提供一种筛选肿瘤启动和促进剂的敏感工具。
