Guzman R C, Yang J, Rajkumar L, Thordarson G, Chen X, Nandi S
Department of Molecular and Cell Biology and the Cancer Research Laboratory, University of California, Berkeley, CA 94720, USA.
Proc Natl Acad Sci U S A. 1999 Mar 2;96(5):2520-5. doi: 10.1073/pnas.96.5.2520.
Full term pregnancy early in life is the most effective natural protection against breast cancer in women. Rats treated with chemical carcinogen are similarly protected by a previous pregnancy from mammary carcinogenesis. Proliferation and differentiation of the mammary gland does not explain this phenomenon, as shown by the relative ineffectiveness of perphenazine, a potent mitogenic and differentiating agent. Here, we show that short term treatment of nulliparous rats with pregnancy levels of estradiol 17beta and progesterone has high efficacy in protecting them from chemical carcinogen induced mammary cancers. Because the mammary gland is exposed to the highest physiological concentrations of estradiol and progesterone during full term pregnancy, it is these elevated levels of hormones that likely induce protection from mammary cancer. Thus, it appears possible to mimic the protective effects of pregnancy against breast cancer in nulliparous rats by short term specific hormonal intervention.
年轻时足月妊娠是女性预防乳腺癌最有效的自然保护方式。用化学致癌物处理过的大鼠，先前的一次妊娠同样能保护其免受乳腺癌变。如强效促有丝分裂和分化剂奋乃静相对无效所表明的那样，乳腺的增殖和分化并不能解释这一现象。在此，我们表明，用妊娠水平的17β-雌二醇和孕酮对未生育大鼠进行短期处理，在保护它们免受化学致癌物诱发的乳腺癌方面具有高效性。由于在足月妊娠期间乳腺会接触到最高生理浓度的雌二醇和孕酮，很可能是这些升高的激素水平诱导了对乳腺癌的保护作用。因此，通过短期特定的激素干预，似乎有可能在未生育大鼠中模拟妊娠对乳腺癌的保护作用。
