Development of cambinol analogues as antilymphoma agents

描述（由申请人提供）：本提案的目的是合成和评价cambinol（一种人NAD依赖性脱乙酰酶SIRT 1和SIRT 2的小分子抑制剂）的类似物，并验证SIRT 1和/或SIRT 2作为生殖中心淋巴瘤的治疗靶点。SIRT 1、SIRT 2和其它NAD依赖性脱乙酰酶已经涉及对应激的细胞应答的控制和通过重要调节蛋白（包括p53和BCL 6癌蛋白）的脱乙酰化的肿瘤发生。我们已经鉴定了一种我们命名为cambinol的化合物，它抑制人SIRT 1和SIRT 2的NAD依赖性脱乙酰酶活性。与SIRT 1在应激期间促进细胞存活的作用一致，在遗传毒性应激期间用cambinol抑制SIRT 1活性导致关键应激反应蛋白的超乙酰化并促进细胞周期停滞。用cambinol作为单一药物治疗表达BCL 6的伯基特淋巴瘤（BL）和弥漫性大B细胞淋巴瘤（DLBCL）细胞诱导细胞凋亡，并伴随BCL 6和p53的过度乙酰化。由于乙酰化使BCL 6失活并激活p53和其他检查点途径，因此cambinol在BL细胞中的抗肿瘤活性可能是由于BCL 6失活和检查点激活的联合作用。在初步研究中，cambinol在小鼠中耐受性良好，并抑制BL异种移植物的生长。生殖中心是B细胞在经历体细胞超突变和类别转换重组的同时快速增殖的发育阶段。尽管基因组不稳定，但生发中心细胞的快速增殖部分是通过BCL 6依赖性和其他转录抑制机制抑制DNA损伤检查点来实现的。基于SIRT 1和SIRT 2（SIRT 1/2）作为作用于许多靶点的蛋白质脱乙酰酶的已知作用，我们假设SIRT 1和/或SIRT 2控制可用于治疗淋巴瘤的生发中心B细胞中的基本转录程序。我们将在一个收敛的研究项目中检验这一假设。我们将：1）开发cambinol的亚型特异性类似物，并组装SIRT 1和SIRT 2亚型特异性抑制剂的SAR; 2）。SIRT 1和/或SIRT 2作为生发中心来源的淋巴瘤的抗癌药物靶点。生发中心的形成将作为B细胞淋巴瘤发生的替代; 3）。确定SIRT 1/2介导的BCL 6的脱乙酰化在cambinol的抗淋巴瘤活性中的作用，和; 4）。使用小鼠中的人淋巴瘤异种移植物和DLBC淋巴瘤的转基因小鼠模型确定优化的SIRT 1/2抑制剂的体内活性。这些跨学科的研究将为NAD依赖性脱乙酰酶作为可行的抗癌药物靶点提供关键验证。 公共卫生相关性：我们建议开发针对SIRT 1的新的抗淋巴瘤药物，SIRT 1是一种参与调节细胞对压力的反应以及细胞分化的酶。细胞分化的失调导致几乎所有淋巴瘤的发展。我们的初步数据表明，抑制SIRT 1和SIRT 2可能对B细胞淋巴瘤细胞是致命的，并使许多其他癌细胞类型对应激条件如标准细胞毒性化疗敏感。我们的目标是利用药物化学，蛋白质晶体学，生物化学和细胞生物学的工具，开发有效的和选择性的SIRT 1抑制剂作为抗淋巴瘤药物。

DESCRIPTION (provided by applicant): The goal of this proposal is to synthesize and evaluate analogues of cambinol, a small molecule inhibitor of human NAD-dependent deacetylases SIRT1 and SIRT2, and to validate SIRT1 and/or SIRT2 as therapeutic targets in germinal center lymphomas. SIRT1, SIRT2 and other NAD- dependent deacetylases have been implicated in control of cellular responses to stress and in tumorigenesis through deacetylation of important regulatory proteins including p53 and the BCL6 oncoprotein. We have identified a compound we named cambinol that inhibits NAD-dependent deacetylase activity of human SIRT1 and SIRT2. Consistent with the role of SIRT1 in promoting cell survival during stress, inhibition of SIRT1 activity with cambinol during genotoxic stress leads to hyperacetylation of key stress response proteins and promotes cell cycle arrest. Treatment of BCL6- expressing Burkitt's lymphoma (BL) and diffuse large B-cell lymphoma (DLBCL) cells with cambinol as a single agent induces apoptosis and is accompanied by hyperacetylation of BCL6 and p53. Because acetylation inactivates BCL6 and activates p53 and other checkpoint pathways, the antitumor activity of cambinol in BL cells may be due to a combined effect of BCL6 inactivation and checkpoint activation. In preliminary studies, cambinol was well tolerated in mice and inhibited growth of BL xenografts. Germinal center is a developmental stage when B-cells proliferate rapidly while undergoing somatic hypermutation and class switch recombination. Rapid proliferation of germinal center cells in spite of genomic instability is accomplished in part through suppression of DNA-damage checkpoints through BCL6-dependent and other transcriptional repression mechanisms. Based on the known roles of SIRT1 and SIRT2 (SIRT1/2) as protein deacetylases that act on a number of targets, we hypothesize that SIRT1 and/or SIRT2 controls essential transcriptional programs in germinal center B-cells that can be exploited for treatment of lymphoma. We will test this hypothesis in a convergent research program. We will: 1) Develop isoform specific analogues of cambinol and assemble an SAR for SIRT1 and SIRT2 isoform specific inhibitors; 2). Validate SIRT1 and/or SIRT2 as anticancer drug targets for germinal center-derived lymphomas. Germinal center formation will serve as a surrogate for B-cell lymphomagenesis; 3). Determine the role of SIRT1/2- mediated deacetylation of BCL6 in cambinol's antilymphoma activity, and; 4). Determine the activity of optimized SIRT1/2 inhibitors in vivo using human lymphoma xenografts in mice and in the transgenic mouse model of DLBC lymphomas. These interdisciplinary studies will provide critical validation for NAD-dependent deacetylases as viable anticancer drug targets. PUBLIC HEALTH RELEVANCE: We propose to develop new anti-lymphoma drugs that target SIRT1, an enzyme involved in regulating cells' response to stress as well as cellular differentiation. Deregulation of cellular differentiation leads to the development of almost all lymphomas. Our preliminary data suggest that inhibition of SIRT1 and perhaps SIRT2 is lethal to B- cell lymphoma cells and sensitizes many other cancer cell types to conditions of stress such as standard cytotoxic chemotherapy. Our goal is to use the tools of medicinal chemistry, protein crystallography, biochemistry and cell biology to develop potent and selective inhibitors of SIRT1 as anti-lymphoma drugs.