The Development of Novel Inhibitors of BCL2 Gene Expression as Anticancer Therape

项目摘要 逃避细胞凋亡是癌症的一个标志，与肿瘤的发生、肿瘤的维持和 对常规化疗产生抗药性。BCL-2是第一个被发现的抗细胞凋亡因子，是其成员 参与调节细胞程序性死亡的bcl-2蛋白家族。BCL-2在肿瘤发生中的作用 在多发性淋巴系统恶性肿瘤的生存中起主导作用，并因此成为活跃的靶点 对于寻求重新激活癌细胞中休眠的凋亡信号或增强 细胞毒性抗癌药物的活性。唯一基于小分子的方法是以BH3为靶标 Bcl2的结合域，从而阻断与其他促凋亡的Bcl2家族成员的相互作用。然而， 由于发生肿瘤溶解，最近暂停了BH3模拟ABT-119的临床试验 综合症，使人们对BH3模拟方法的潜在安全性产生了一些怀疑，并增加了对 寻找靶向bcl2的替代策略。 与许多其他在癌症的发生和维持中协同作用的基因一样，bcl2 在其启动子区域包含一个高度可塑性的富含GC的转录调控元件。开创性的工作在 亚利桑那大学已经证明，这种调控元件能够形成二级DNA 被称为G-四链DNA(富G链)和I-基序DNA(富C链)的结构，以及这些DNA 二级结构调节转录。一种高通量筛查试验，旨在识别 能够稳定/破坏bcl-2 I-基序序列的分子从 类固醇化学型(IMC-76)。后来的研究表明，IMC-76降低了bcl2的表达 在细胞培养和小鼠移植瘤细胞中的表达。重要的是，IMC-76显著增强了 常规化疗药物在细胞培养中诱导细胞凋亡并显示出相当大的协同作用 当与化疗药物联合应用于小鼠肿瘤异种移植模型。 这项提议的最终目标是将适当优化的IMC-76类似物推进到IND启用研究中 以及最终的1期临床试验。我们建议进行一轮有限的合成化学实验，目的是 优化bcl2在细胞内的表达及与细胞毒抗癌药物的协同作用 文化。此外，这种优化策略将允许我们探索潜在的脱离目标的相关影响 在生化核受体分析中通过筛选类似物与类固醇化学类型有关。合格的销售线索 分子将在大鼠身上进行药代动力学分析，包括慢性和急性耐受性研究 小鼠，以及联合标准护理化疗药物对淋巴瘤小鼠的疗效研究 异种移植模型。总的来说，这些研究将使我们能够选择一位最佳的候选人 进入正式的临床前研究。

Project Summary Evasion of apoptosis is a hallmark of cancer and is associated with oncogenesis, tumor maintenance, and resistance to conventional chemotherapy. BCL-2 was the first identified anti-apoptotic factor and is a member of the BCL-2 family of proteins that cooperate in the regulation of programmed cell death. BCL-2 plays a dominant role in the survival of multiple lymphoid malignancies and has consequently become an active target for drug discovery programs seeking to reactivate dormant apoptotic signaling in cancer cells or enhance the activity of cytotoxic anticancer drugs. The only small-molecule-based approach has been to target the BH3 binding domain of Bcl-2, thereby blocking interaction with other pro-apoptotic Bcl-2 family members. However, the recent suspension of the BH3 mimetic ABT-119 from clinical trials, due to the occurrence of tumor lysis syndrome, has cast some doubt over the potential safety of the BH3 mimetic approach and increased the need for alternative strategies to target BCL-2. In common with many other genes that cooperate in the development and maintenance of cancer, BCL-2 contains a highly plastic, GC-rich transcriptional regulatory element in its promoter region. Pioneering work at the University of Arizona has shown that this regulatory element is capable of forming DNA secondary structures called G-quadruplex DNA (G-rich strand) and i-motif DNA (C-rich strand) and that these DNA secondary structures regulate transcription. A high-throughput screening assay designed to identify small molecules capable of stabilizing/destabilizing the BCL-2 i-motif sequence produced a small molecule from the steroidal chemotype (IMC-76). Subsequent studies have demonstrated that IMC-76 decreases BCL-2 expression in cell culture and in mouse xenograft tumor cells. Importantly, IMC-76 significantly potentiates apoptosis induced by conventional chemotherapy drugs in cell culture and demonstrates considerable synergy when combined with chemotherapy drugs in mouse cancer xenograft models. The ultimate goal of this proposal is to advance suitably optimized analogs of IMC-76 into IND-enabling studies and eventual phase 1 clinical trials. We propose a limited round of synthetic chemistry for the purpose of optimizing potency for lowering BCL-2 expression in cells and synergy with cytotoxic anticancer drugs in cell culture. Furthermore, this optimization strategy will allow us to explore potential off-target effects associated with the steroidal chemotype by screening analogs in biochemical nuclear receptor assays. Qualified lead molecules will be subjected to pharmacokinetic analysis in rats, both chronic and acute tolerability studies in mice, and efficacy studies in combination with standard-of-care chemotherapy drugs in lymphoma mouse xenograft models. Collectively these studies will enable us to select an optimized lead candidate for advancement into formal preclinical studies.