Genomic Markers of Breast Cancer Prevention Induced by hCG in Women at High Risk

描述（由申请人提供）：这一假设得到了以下观察结果的支持：怀孕和母乳喂养降低了散发性和brca1相关乳腺癌的风险，并且在实验模型中，使用胎盘激素hCG治疗也提供了类似程度的保护。由于BRCA1突变携带者的终生乳腺癌风险增加85%，肿瘤发生的年龄明显低于散发性癌症，并且由于其雌激素受体α (ERa)、孕激素受体（PR）和Her2呈阴性，对内分泌和免疫治疗无反应，这些因素使其预后恶化，因此这一高危人群是实施基于使用r-hCG作为化学预防剂的预防措施的理想目标。我们的研究结果支持了这种方法，即妊娠诱导的乳房完全分化是赋予女性和啮齿类动物保护的主要机制之一，其中用hCG治疗处女大鼠可以防止化学诱导的乳腺癌的发生和发展。此外，我们已经证明，乳房印记的分化是一种特定的基因组特征，是分娩妇女的特征，因此可以作为一生中乳腺癌风险降低的生物标志物。在这项探索性应用中，我们的目标是建立原理证明，即用重组人绒毛膜促性腺激素（r-hCG）治疗“高乳腺癌风险”妇女将改变其乳腺上皮的高风险基因组谱，使其与有早期足月妊娠史的妇女相似。为此，将从18名携带BRCA1有害突变的女性中随机抽取乳晕周围细针穿刺（RPFNA）收集乳腺上皮细胞。对细胞进行细胞病理学评估；提取RNA，通过cDNA微阵列分析基因表达，并通过Ki67、ER和PR状态进行细胞增殖的免疫细胞化学测定，这些参数将作为“高风险”基因组图谱的基线。我们建议测试90天（3个月）的r-hCG治疗是否会激活或下调与免疫监视、DNA修复、程序性细胞死亡、转录和染色质结构/激活因子/共激活因子相关的基因，与治疗前的基因组图谱相比，这些变化将表明“高风险”已转化为“低风险”风险基因组特征，例如在有早期足月妊娠史的妇女中发现的。这些知识将作为在本项目完成后建立新的基因组特征作为大型预防性临床试验的中间生物标志物的基础。

DESCRIPTION (provided by applicant): This hypothesis is supported by the observations that pregnancy and breastfeeding reduce the risk of both sporadic and BRCA1-associated breast cancer, and that treatment with the placental hormone hCG confers a similar degree of protection in experimental models. Because the lifetime breast cancer risk of BRCA1 mutation carriers is increased by 85%, tumors arise in them at a significantly lower age than sporadic cancers, and in addition they are unresponsive to endocrine and immunotherapy due to their negativity for estrogen receptor alpha (ERa), progesterone receptor (PR), and Her2, factors that worsen their prognosis, this high risk population is an ideal target for implementing preventive measures based on the use of r-hCG as a chemopreventive agent. This approach is supported by our demonstration that the complete differentiation of the breast induced by pregnancy is one of the main mechanisms that confer protection to both women and rodents, in which treatment of virgin rats with hCG prevents the initiation and progression of chemically induced mammary cancer. Furthermore, we have demonstrated that the differentiation of the breast imprints a specific genomic signature that is characteristic of parous women and could serve therefore as a biomarker indicative of the lifetime decreased breast cancer risk. In this exploratory application we are aiming at establishing the proof of principle that treatment of "high breast cancer risk" women with recombinant human chorionic gonadotropin (r-hCG) will change their breast epithelium's high risk genomic profile to one similar to that identified in women with a history of early full first term pregnancy. For this purpose, breast epithelial cells will be collected by random periareolar fine needle aspiration (RPFNA) from 18 women carriers of BRCA1 deleterious mutations. Cells will be cytopathologically evaluated; RNA will be extracted for analysis of gene expression by cDNA microarray, and immunocytochemical determination of cell proliferation by Ki67, ER and PR status, parameters that will serve as a baseline of the "high risk" genomic profile. We propose to test whether a 90 day (3-month) treatment with r-hCG will activate or downregulate genes related to immune surveillance, DNA repair, programmed cell death, transcription, and chromatin structure/activators/co activators in comparison with the pre-treatment genomic profile, changes that will indicate that the "high risk" has been converted to a "low risk" risk genomic signature, such as that found in women with a history of early first full term pregnancy. This knowledge will serve as the basis for establishing novel genomic signatures as intermediate biomarkers for larger preventive clinical trials at the completion of this project.