Development of cambinol analogues as antilymphoma agents

描述(申请人提供)：这项建议的目标是合成和评估龙脑醇的类似物，一种人类NAD依赖的脱乙酰基酶SIRT1和SIRT2的小分子抑制剂，并验证SIRT1和/或SIRT2作为生发中心淋巴瘤的治疗靶点。SIRT1、SIRT2和其他依赖NAD的脱乙酰酶通过P53和BCL6癌蛋白等重要调节蛋白的脱乙酰基参与控制细胞对应激的反应和肿瘤的发生。我们已经确定了一种名为龙脑酚的化合物，它可以抑制人SIRT1和SIRT2的NAD依赖的脱乙酰酶活性。与SIRT1在应激过程中促进细胞存活的作用一致，在基因毒性应激过程中，用樟脑抑制SIRT1活性会导致关键应激反应蛋白的超乙酰化，并促进细胞周期停滞。樟脑作为单一药物治疗表达BCL6的Burkitt淋巴瘤(BL)和弥漫性大B细胞淋巴瘤(DLBCL)细胞可诱导细胞凋亡，并伴随BCL6和P53的高乙酰化。由于乙酰化可使BCL6失活，并激活P53等检查点通路，因此樟脑的抗肿瘤活性可能是BCL6失活和检查点激活共同作用的结果。在初步研究中，樟脑醇在小鼠体内耐受性良好，并抑制了BL异种移植瘤的生长。生发中心是B细胞在经历体细胞高突变和类切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bcl6依赖的转录抑制机制和其他转录抑制机制来抑制DNA损伤检查点。根据已知的SIRT1和SIRT2(SIRT1/2)作为作用于许多靶点的蛋白质去乙酰酶的作用，我们假设SIRT1和/或SIRT2控制生发中心B细胞的基本转录程序，可用于淋巴瘤的治疗。我们将在一个趋同的研究计划中检验这一假设。我们将：1)开发龙脑醇的异构体特异性类似物，并组装针对SIRT1和SIRT2异构体特异性抑制剂的SAR；2)。验证SIRT1和/或SIRT2作为生发中心淋巴瘤的抗癌药物靶点。生发中心的形成将替代B细胞淋巴瘤的发生；确定SIRT1/2介导的BCL6脱乙酰基在樟脑抗淋巴瘤活性中的作用；在小鼠人淋巴瘤异种移植和DLBC淋巴瘤转基因小鼠模型中，确定优化的SIRT1/2抑制剂的体内活性。这些跨学科研究将为NAD依赖的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SIRT1的新的抗淋巴瘤药物，SIRT1是一种参与调节细胞对压力的反应以及细胞分化的酶。放松对细胞分化的调控会导致几乎所有淋巴瘤的发生。我们的初步数据表明，抑制SIRT1和SIRT2对B细胞淋巴瘤细胞是致命的，并使许多其他类型的癌细胞对应激条件敏感，如标准的细胞毒化疗。我们的目标是利用药物化学、蛋白质结晶学、生物化学和细胞生物学的工具，开发有效和选择性的SIRT1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.