Study on the protection against estrogen-dependent cancer

研究乳腺癌组织中雌激素的动态变化、临床病理和预后因素与参与雌激素合成和雌激素信号转导系统的9种雌激素相关酶的表达水平的相关性。ErbB2、芳香化酶和类固醇硫酸酯酶的高表达是良好的预后因素，ER-α和细胞周期蛋白D2的高表达是不良的预后因素。接下来，研究了雌激素在体内的致癌作用。一种化学致癌物的DMBA在芳香型基因敲除小鼠(雌激素缺乏小鼠)中引起罕见的肿瘤形成，而在野生小鼠中发生的几率很高。此外，在cyplB1转基因小鼠中经常观察到雌激素依赖性的肿瘤发生，提示雌激素通过细胞色素P1B1代谢为活性致癌物。为了分析癌组织中癌细胞-间质细胞相互作用与临床病理因素的关系，制备了携带ERE-GFP的MCF7细胞，并用荧光GFP探针通过这种相互作用示踪癌细胞中ER的激活。结果表明，乳腺癌组织间质细胞中GFP的表达有所不同，绝经后组织中GFP的表达高于绝经前组织。不同病例对芳香酶抑制剂的敏感性也不同。最后，使用具有不同雌激素代谢谱的稳定转化MCF7细胞，分析了癌细胞内雌激素动态与癌细胞增殖能力和对芳香酶抑制剂敏感性的相关性。因此，类固醇硫酸酯酶间接合成雌激素也在雌激素供应给癌细胞和芳香酶直接合成雄激素中起重要作用，并提示类固醇硫酸酯酶抑制剂和雌激素磺基转移酶诱导剂作为抗癌药物的可能性。

The estrogen dynamics in breast cancer tissues, correllation of clinicopathological and prognostic factors with expression levels of 9 kinds of estrogen-related enzymes participating in the estrogen synthesis and estrogen-signal transducing system, was examined. High level expression of ErbB2, aromatase, and steroid sulfatase was a good prognostic factor, whereas that of ER-alfa and cyclin D2 was a poor prognostic factor. Next, in vivo carcinogenesis by estrogens was examined. DMBA of a chemical carcinogen caused rare tumorigenesis in aromataes-knockout mice (estrogen deficeint mice), in contrast with high frequency in wild mice. Furthermore, it was often observed in cyplBl-transgenic mice to estrogen-dependently suffered from tumors, suggesting that estrogens were metabolized to active carcinogens by cyp1B1. To analyze relationship between cancer cells-stromal cells interaction in the cancer tissues and clinicopathological factors, MCF7 cells carrying ERE-GFP was prepared and used for tracing ER activation in the cancer cells through the interaction by a means of a fluorescent GFP probe. The results indicated that GFP expression vary among stromal cells from breast cancer tissues and were more frequently induced in the postmenopausal tissues than in premenopausal ones. Sensitivities to aromatase inhibitors was also varied among the individual cases. Finally, correlation of estrogens dynamics in the cancer cells with proliferative capability and sensitivities of cancer cells to aromatase inhibitors was analyzed using stable transformant MCF7 cells with various profiles of estrogen metabolism. Consequently, it was indicated that indirect synthesis of estrogens from estrogen sufates by steroid sulfatase also plays an important role in the supply of estrogens to cancer cells as well as direct synthesis from androogens by aromatase, and suggested a possibility of steroid sulfatase inhibitors and estrogen sulfotransferase inducers as anti-cancer drugs.