Targeting Leukemias with Bcl2 BH3 Helical Peptides

描述(由申请人提供)： 恶性肿瘤通常以程序性细胞死亡(PCD)缺陷为特征。 导致放射和化疗反应受阻的通路。 这些缺陷通常表现为Bcl-2超家族的失衡 将生存和死亡信号与核心PCD机制联系起来的蛋白质。 BCL-2在约50%的癌症中过度表达。最慢性淋巴细胞 白血病(CLL)和许多急性髓系白血病(AML)和急性 淋巴细胞白血病(ALL)过表达抗凋亡基因Bcl2。功能性 体外研究表明，Bc l-2家族蛋白在 维持这些白血病细胞的存活并促进其 对化疗有抵抗力。 我们假设细胞凋亡是由细胞的异二聚化控制的 相互竞争的Bcl-2家族抑制物、诱导物和效应物最终 确定诱导剂是否通过 线粒体膜。异二聚化通过BH3结构域结合发生 口袋里。我们实验室的初步实验重复地证明了 一个受限制的α-螺旋Bak BH3结构域多肽(16mer)来自 促凋亡蛋白Bak，但不是野生型不受限制的肽， 覆盖阻断(S)对新鲜分离的白血病细胞的凋亡。这个 α-螺旋结构是BH3高亲和力结合所必需的 多肽，因此受限制的BH3多肽比 不受约束的线状多肽。 我们建议(1)测试各种策略，以改善 BAK BH3多肽及其限制性螺旋BH3多肽的合成 从其他效应器(BAX、BAK)和诱导器(BID)，(2)评估其 慢性粒细胞白血病和急性髓系白血病细胞促凋亡活性及敏感性的研究 未经治疗和复发/难治的个体，(3)确定 通过比较Bcl-2家族蛋白的亲和力来研究促凋亡BH3多肽 和(4)将有效的促凋亡多肽连接到膜通透性多肽上，以 针对白血病细胞的测试。BH3多肽可以提供强大的工具 支持生产小分子的努力的概念验证数据 模拟Bcl-2家族蛋白的化合物用于治疗白血病和 用于确定细胞存活和对化疗耐药的机制。

DESCRIPTION (provided by applicant): Malignancies are often characterized by defects in programmed cell death (PCD) pathways contributing to blocks in responses to irradiation and chemotherapy. These defects are frequently manifested by imbalances in the Bcl-2 superfamily of proteins that link survival and death signals to the core PCD machinery. Bcl-2 is over-expressed in about 50% of all cancers. Most chronic lymphocytic leukemias (CLLs) and many Acute Myelogenous Leukemias (AMLs) and Acute Lymphocytic Leukemias (ALLs) over-express anti-apoptotic Bcl-2. Functional studies in vitro suggest an important role for Bcl-2 family proteins in maintaining the survival of these leukemic cells and promoting their resistance to chemotherapy. We hypothesize that apoptosis is controlled by the heterodimerization of competing Bcl-2 family inhibitors, inducers and effectors which ultimately determine whether the inducers channel apoptotic proteins through mitochondrial membranes. Heterodimerization occurs via BH3-domain binding pockets. Preliminary experiments from our laboratory reproducibly demonstrates that a constrained alpha-helical Bak BH3-domain peptide (16 mer) from the pro-apoptotic protein Bak, but not a wild-type unconstrained peptide, overrides block(s) to apoptosis in freshly isolated leukemia cells. The alpha-helical structure is essential for high affinity binding of BH3 peptides, and therefore constrained BH3 peptides are more potent than unconstrained linear peptides. We propose to (1) test various strategems for improving the activity of the Bak BH3 peptide as well as for synthesizing constrained helical BH3 peptides from additional effectors (Bax, Bak) and an inducer (Bid), (2) assess their pro-apoptotic activities and the sensitivities of CLL and AML cells from untreated and relapsed/refractory individuals, (3) identify the targets of pro-apoptotic BH3 peptides by comparing affinities for Bcl-2 family proteins and (4) link a potent pro-apoptotic peptide to membrane permeable peptides for tests against leukemic cells. BH3 peptides could provide powerful tools for proof of concept data in support of efforts to generate small-molecule compounds that mimic Bcl-2 family proteins for the treatment of leukemia and for identifying mechanisms of cell survival and resistance to chemotherapy.