Development of BRCA1-mimetic drugs for breast cancer

描述（由申请人提供）：我们在过去的10年里研究了乳腺癌易感基因-1 （BRCA1）和雌激素受体（ER-1）的功能相互作用。在这些研究中，我们观察到BRCA1在乳腺癌细胞中强烈抑制ER-1活性，并阻断雌激素（E2）刺激的基因表达和细胞增殖。BRCA1对ER-1活性的抑制是由于BRCA1和ER-1蛋白的物理相互作用，我们以高分辨率绘制了这一图谱。从这些研究中，我们生成了BRCA1: ER-1复合物的3D模型，并对一个小分子文库进行了虚拟筛选，以确定可能作为“BRCA1模拟物”的化合物，以深入插入ER-1的关键接触点。在我们测试的40种这样的化合物中，6种强烈抑制ER-1活性，包括几种在浓度仅为3-4 <M时产生50%抑制的化合物。假设。BRCA1介导许多功能，包括其作为保护基因组完整性的看守基因的作用。然而，BRCA1的这种作用并不能解释为什么突变携带者在特定肿瘤类型，特别是乳腺癌中表现出过高的发病率。我们假设，虽然其看护功能有助于肿瘤抑制，但BRCA1抑制乳腺癌发展需要其抑制ER-1活性的能力。相反，通过使用模拟BRCA1: ER-1物理相互作用关键方面的小分子化合物，恢复或增强这一功能将有可能预防乳腺癌。目标。为了验证这一假设，我们将开展四个具体目标：1)研究“brca1模拟物”药物在人乳腺癌细胞中的作用机制；2)大量生成现有先导化合物，并合成先导化合物的结构类似物，以生产更有效的化合物；3)在异种移植模型中测试先导化合物和最佳类似物在体内抑制雌激素刺激的人乳腺癌肿瘤生长的能力；4)在几种转基因小鼠模型中测试几种化合物预防早期乳腺癌发展的能力。的意义。我们的最终目标是开发预防和/或治疗乳腺癌的新药。重要的是，brca1模拟化合物与ER-1的相互作用方式不同于选择性雌激素受体调节剂（SERMs），如他莫昔芬和雷洛昔芬。因此，它们可能单独使用，或与现有药物联合使用，或用于激素抵抗性乳腺癌。公共卫生相关性：BRCA1（乳腺癌1型，早期发病）是一种人类基因，属于一类被称为肿瘤抑制因子的基因，其维持基因组完整性以防止不受控制的增殖。BRCA1基因的遗传变异（突变）与几种遗传性癌症类型有关，包括乳腺癌和卵巢癌。这项研究的目标是开发类似药物的小分子化合物，模拟BRCA1蛋白插入雌激素受体蛋白并抑制雌激素作用的能力。这些“brca1模拟物”化合物可能对预防和/或治疗乳腺癌有用。

DESCRIPTION (provided by applicant): We have studied the functional interaction of the breast cancer susceptibility gene-1 (BRCA1) and the estrogen receptor (ER-1) for the past 10 years. During these studies, we observed that BRCA1 strongly inhibits ER-1 activity in breast cancer cells and blocks estrogen (E2)-stimulated gene expression and cell proliferation. The BRCA1 repression of ER-1 activity is due to a physical interaction of the BRCA1 and ER- 1 proteins, which we mapped at high resolution. From these studies, we generated a 3D model of the BRCA1: ER-1 complex and performed virtual screening of a small molecule library to identify compounds that might act as "BRCA1-mimetics" to insert deeply into ER-1 at key contact points. Of 40 such compounds that we tested, 6 strongly inhibited ER-1 activity, including several that yielded 50% inhibition at concentrations of only 3-4 <M. Hypothesis. BRCA1 mediates a number of functions, including its role as a caretaker gene in preserving genomic integrity. However, this role for BRCA1 does not explain why mutation carriers exhibit an excess incidence of specific tumor types, particularly breast cancer. We hypothesize that while its caretaker function contributes to tumor suppression, BRCA1 suppression of breast cancer development requires its ability to inhibit ER-1 activity. Conversely, it will be possible to prevent breast cancer by restoring or enhancing this function, using small molecule compounds that mimic critical aspects of the BRCA1: ER-1 physical interaction. Objectives. To test this hypothesis, we will carry out four specific aims: 1) To study the mechanism of action of "BRCA1-mimetic" drugs in human breast cancer cells; 2) To generate large quantities of our current lead compounds and synthesize structural analogs of the lead compounds to produce more potent compounds; 3) To test the lead compound and best analog(s) for their ability to inhibit estrogen-stimulated human breast cancer tumor growth in vivo in a xenograft model; and 4) To test the ability of several compounds to prevent the early stages of mammary cancer development in several mouse transgenic models. Significance. Our ultimate goal is to develop novel drugs for breast cancer prevention and/or treatment. Importantly, the BRCA1-mimetic compounds interact with ER-1 in a manner that is distinct from that of the selective estrogen receptor modulators (SERMs), such as Tamoxifen and Raloxifene. Thus, they may be useful by themselves, in combination with existing agents, or in cases of hormone-resistant breast cancer. PUBLIC HEALTH RELEVANCE: BRCA1 (breast cancer 1, early onset) is a human gene that belongs to a class of genes known as tumor suppressors, which maintain genomic integrity to prevent uncontrolled proliferation. Inherited variations (mutations) in the BRCA1 gene have been implicated in several hereditary cancer types, including breast and ovarian cancers. The goal of this research is to develop small molecule drug-like compounds that mimic the ability of the BRCA1 protein to insert into the estrogen receptor protein and inhibit estrogen action. These "BRCA1-mimetic" compounds may be useful in the prevention and/or treatment of breast cancer.