MECHANISMS OF ENVIRONMENTAL AGENTS INDUCED BREAST CANCER

本研究的长期目标是l）将正常人 乳腺上皮细胞（HBEC）在体外逐步进入不同阶段， 癌前和恶性细胞的化学\物理致癌物和 癌基因; 2）确定是否有一种类型的HBEC（I型）与干细胞和 腔上皮细胞的特性是肿瘤的靶细胞 各种乳腺癌物质的转化; 3）以确定 在肿瘤转化阶段，不同的已知乳腺癌致癌物 最有效地发挥其作用;和4）阐明遗传 和乳腺癌发生的分子机制。为此，使用两个 影响乳腺癌发生的最佳已知试剂（即电离 辐射和雌激素化合物），我们建议1）确定是否电离 辐射是肿瘤的有效引发剂、促进剂或进展剂， 正常HBEC的转化（具有延长的寿命，不朽，弱 致瘤性和高致瘤性作为终点）; 2）发展 表达雌激素受体（ER）的正常和癌前HBEC， 对雌激素的细胞增殖反应; 3）测试是否以及如何 雌激素化合物影响ER阳性正常人的肿瘤转化 和癌前HBEC;和4）表征生物学和分子生物学特征， 电离辐射诱导的癌前和肿瘤性HBEC的性质 辐射/雌激素揭示乳腺癌的遗传和分子机制 致癌作用为了实现这些特定的目标，一种新的培养技术 已经开发了两种类型的正常HBEC， 技术，如比较基因组杂交的分子 细胞遗传学分析和北方，Western blot分析，RT-PCR，DNA 测序、免疫染色、激光细胞计数将用于确定 癌前病变中各种癌基因、抑癌基因的表达 以及不同阶段的肿瘤细胞。 除了有可能 阐明乳腺癌的发生机制， 该系统将有助于识别环境致癌物， 开发用于乳房X射线照相术的潜在辐射保护器， 乳腺癌的化学预防/治疗策略（例如， 目标正常或癌前HBEC的分化）。

The long-term objectives of this study are l) to transform normal human breast epithelial cells (HBEC) in vitro stepwise to various stages of preneoplastic and malignant cells by chemical\physical carcinogens and oncogenes; 2) to determine if one type of HBEC (Type I) with stem cell and luminal epithelial cell characteristics is the target cell for neoplastic transformation by various breast carcinogens; 3) to determine at which stage of neoplastic transformation, different known breast carcinogens are most effective in exerting their effects; and 4) to elucidate the genetic and molecular mechanisms of breast carcinogenesis. To these ends, using two best known agents that affect breast carcinogenesis (i.e. ionizing radiation and estrogenic compound), we propose 1) to determine if ionizing radiation is a potent initiator, promotor or progressor for neoplastic transformation of normal HBEC (with extended lifespan, immortality, weak tumorigenicity, and high tumorigenicity as end points); 2) to develop normal and preneoplastic HBEC that express estrogen receptor (ER) and respond to estrogens for cell proliferation; 3) to test if and how estrogenic compounds affect neoplastic transformation of ER-positive normal and preneoplastic HBEC; and 4) to characterize the biological and molecular nature of preneoplastic and neoplastic HBEC induced by ionizing radiation/estrogen to reveal the genetic and molecular mechanisms of breast carcinogenesis. To accomplish these specific aims, a new culture technique to grow two types of normal HBEC has been developed and molecular techniques, such as comparative genomic hybridization for molecular cytogenetic analysis and Northern, Western blot analysis, RT-PCR, DNA sequencing, immunostaining, laser cytometry will be used to determine the expression of various oncogene, tumor suppressor genes for preneoplastic and neoplastic cells at different stages. Besides the potential to elucidate the mechanism of breast carcinogenesis, the development of this system will be instrumental in identifying environmental carcinogens and in developing potential radiation protectors for mammography and chemopreventive/therapeutic strategies for breast cancer (e.g. differentiation of target normal or preneoplastic HBEC).