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 对放射和化疗反应的阻断途径。 这些缺陷通常表现为Bcl-2超家族的不平衡 将生存和死亡信号与核心PCD机制联系起来的蛋白质。 Bcl-2在大约50%的癌症中过度表达。大多数慢性淋巴细胞 白血病（CLL）和许多急性髓细胞性白血病（AML）和急性白血病（AML）。 淋巴细胞白血病（ALL）过度表达抗凋亡Bcl-2。功能 体外研究表明Bcl-2家族蛋白在 维持这些白血病细胞的存活， 对化疗的抵抗力。 我们假设细胞凋亡是由异源二聚化的 竞争性Bcl-2家族抑制剂、诱导剂和效应剂， 确定诱导剂是否通过 线粒体膜通过BH 3结构域结合发生异源二聚化 口袋我们实验室的初步实验重复性地证明了 来自于人的限制性α-螺旋巴克BH 3-结构域肽（16聚体） 促凋亡蛋白巴克，而不是野生型无约束肽， 在新鲜分离的白血病细胞中，它可以抑制细胞凋亡。的 α-螺旋结构对于BH 3的高亲和力结合是必需的 肽，因此限制性BH 3肽比 无约束线性肽。 我们建议（1）测试各种策略，以提高活性的 巴克BH 3肽以及用于合成受限螺旋BH 3肽 从另外的效应物（Bax，巴克）和诱导物（Bid），（2）评估它们的 CLL和AML细胞的促凋亡活性和敏感性 未治疗和复发/难治性个体，（3）确定 通过比较对Bcl-2家族蛋白的亲和力来鉴定促凋亡BH 3肽 和（4）将有效的促凋亡肽连接到膜渗透肽， 对白血病细胞的测试。BH 3肽可以提供强大的工具， 概念验证数据，以支持生产小分子 用于治疗白血病的模拟Bcl-2家族蛋白的化合物， 用于确定细胞存活和对化疗的抗性的机制。

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.