Breast Cancer Chemoprevention Strategies

描述（由申请人提供）：流行病学研究已经确定雌激素水平升高与乳腺癌发展相关。特别地，天然激素17 β-雌二醇及其儿茶酚代谢物与乳腺癌的发展有关，并且认为雌激素儿茶酚引起自由基介导的直接和/或间接DNA损伤，这可能导致基因突变并最终导致乳腺癌。我们已经检测到几个氧化和其他极性的DMA加合物在大鼠乳腺组织和人类乳腺组织新设计的32 P-后标记/TLC系统。与参考氧化加合物的色谱相似性表明，组织DNA加合物源于自由基介导。这些结果表明，加合物可能是由17-3-雌二醇代谢产物的氧化还原循环引起的。我们假设，联合使用化学预防药物将提供更有效的预防乳腺癌比个别代理。这将通过以下方式实现：1）利用具有不同作用模式的药剂的组合;和2）通过使用新型全身缓释装置来规避毒性。我们的初步结果，通过干预与鞣花酸提供全身缓释系统和饮食引起了类似程度的抑制17-3-雌二醇介导的乳腺肿瘤发生在ACI大鼠模型，支持我们的工作假设。一组经验丰富的研究人员将进行以下具体研究，以满足我们的目标：1）确定选定的药物在体内调节雌激素代谢和DNA修复的功效。2)确定候选药物在体内减少17-3-雌二醇诱导的细胞增殖的功效。3)确定候选药物抑制17-3-雌二醇诱导的乳腺肿瘤发生的效力，并将雌激素代谢的调节与肿瘤指数相关联。4)确定通过缓释装置递送的药物组合是否比单独药物更有效地抑制乳腺肿瘤发生。所得到的数据将揭示，通过不同领域工作的药剂的组合可以提供比单独药剂更完全的乳腺肿瘤预防，并且全身缓释递送可以通过显著降低有效剂量来规避毒性。这些数据还将确定可以有效预防乳腺癌以及其他激素癌症的途径。

DESCRIPTION (provided by applicant): Epidemiological studies have identified an association of elevated levels of estrogens with breast cancer development. In particular, the natural hormone, 17(3-estradiol and its catechol metabolites have been implicated in breast cancer development, and it is believed that estrogen catechols cause free radical mediated, direct and/or indirect DNA damage, which may lead to gene mutations and ultimately breast cancer. We have detected several oxidative and other polar DMA adducts in the mammary tissue of rats and in human breast tissues by newly devised 32P-postlabeling/TLC systems. Chromatographic similarity with reference oxidative adducts suggests that tissue DNA adducts originated from free radical-mediation. These results suggest that the adducts may have resulted from redox cycling of 17-3-estradiol metabolites. We hypothesize that combination of chemopreventive agents will provide more effective prevention of breast cancer than individual agents. This will be accomplished by 1) utilizing combination of agents with different modes of action; and 2) by using a novel systemic slow-release device to circumvent toxicity. Our preliminary results by interventions with ellagic acid delivered by systemic slow-release system and diet elicited similar degree of inhibition of 17-3-estradiol-mediated mammary tumorigenesis in the ACI rat model, supporting our working hypothesis. A team of experienced investigators will pursue the following specific studies to meet our goals: 1) Determine the efficacy of selected agents to modulate estrogen-metabolism and DNA repair in vivo. 2) Determine the efficacy of candidate agents to diminish 17-3-estradiol-induced cell proliferation in vivo. 3) Determine the efficacy of candidate agents to inhibit 17-3-estradiol-induced mammary tumorigenesis, and correlate modulation of estrogen metabolism with tumor indices. 4) Determine if combination of agents delivered by the slow-release device will provide more effective inhibition of mammary tumorigenesis compared with the individual agents. The resulting data will reveal that combination of agents working via different arenas can provide more complete prevention of mammary tumors than individual agents, and that the systemic slow-release delivery can circumvent toxicity by significantly reducing the effective dose. The data will also identify pathway(s) that can be targeted for effective prevention of breast cancer, and perhaps other hormonal cancers.