Nagasawa H, Yanai R, Taniguchi H
Cancer Res. 1976 Jul;36(7 PT 1):2223-6.
DNA synthesis in mammary gland estimated by [3H]thymidine incorporation was significantly higher on the day of proestrus than on the second day of diestrus in 50-day-old female Sprague-Dawley rats. The percentage of progressive mammary tumors, tumor growth rate, and the number and the weight of tumors per tumor-bearing rat were significantly higher in the animals given a single i.v. injection of 5 mg 7,12-dimethylbenz(a)anthracene at proestrus than in the animals given it at diestrus. Inhibition of DNA synthesis at proestrus by 2-bromo-alpha-ergocryptine also suppressed mammary tumorigenesis by the carcinogen. In 90-day-old rats in which little difference was found in mammary gland DNA synthesis between proestrus and diestrus, there was no difference in mammary tumorigenesis between animals given the carcinogen at proestrus and animals given it at diestrus. On the other hand, the prestimulation of mammary gland DNA synthesis by prolactin increased the growth, the number, and the weight of carcinogen-induced mammary tumors. These results demonstrate the importance of mammary DNA synthesis at the time when a carcinogen acts on the glands in mammary tumorigenesis.
通过[3H]胸苷掺入法估算，50日龄雌性斯普拉格-道利大鼠在动情前期乳腺中的DNA合成显著高于动情后期第二天。在动情前期单次静脉注射5毫克7,12-二甲基苯并(a)蒽的动物，其进行性乳腺肿瘤的百分比、肿瘤生长速率以及每只荷瘤大鼠的肿瘤数量和重量，均显著高于在动情后期接受注射的动物。2-溴-α-麦角隐亭在动情前期抑制DNA合成，也抑制了致癌物诱发的乳腺肿瘤发生。在90日龄大鼠中，动情前期和动情后期乳腺DNA合成差异不大，在动情前期给予致癌物的动物与在动情后期给予致癌物的动物之间，乳腺肿瘤发生没有差异。另一方面，催乳素对乳腺DNA合成的预刺激增加了致癌物诱发的乳腺肿瘤的生长、数量和重量。这些结果证明了在致癌物作用于乳腺时乳腺DNA合成在乳腺肿瘤发生中的重要性。
