Targeting the heat shock response for the therapy of DLBCL

描述（由申请人提供）： 我们的提案探讨了弥漫性大B细胞淋巴瘤（DLBCL）的分子发病机制和治疗靶点，DLBCL是非霍奇金淋巴瘤的最常见形式。由于这些肿瘤是明显异质性，我们有兴趣在确定相关机制的DLBCL患者的最广泛的横截面可能。热休克蛋白90（Hsp90）在DLBCL中广泛表达。我们独立地证实并验证了这一结果，并表明Hsp90结合并保护BCL 6转录抑制因子和IKK复合物的NEMO亚基免于降解，这两者都是DLBCL中致癌途径的组成部分。几个研究小组已经开发了Hsp90抑制剂。然而，这些分子中的大多数具有相对窄的治疗窗口，使得不可能在体内完全抑制肿瘤Hsp90。Chiosis实验室开发了一种名为PUH 71的Hsp90嘌呤支架抑制剂。PUH71与其他Hsp90抑制剂相比更有效和特异性地结合Hsp90的部分，该部分在肿瘤细胞内陪伴致癌客户蛋白，并且容易在体外和体内杀死DLBCL细胞。给予小鼠的单剂量PUH71在治疗水平下在淋巴瘤中保留超过48小时，但在短短几小时内迅速从正常组织中清除。因此，PUH71表现出比其他Hsp90抑制剂更宽的治疗窗，因此具有更大的抗DLBCL功效。鉴于这些有希望的结果，美国国家癌症研究所癌症治疗和诊断部门正在赞助PUH 71的翻译用于临床试验。总而言之，我们的初步机制和临床前数据使我们假设Hsp90是DLBCL广泛横截面中的关键治疗靶标，并且DLBCL对Hsp90成瘾，因为它保护DLBCL在其各种亚型中免于参与DLBCL存活的多种途径的降解组分。鉴于其上级的药理学特性，我们预测PUH71将在原发性人DLBCL中具有高度活性，并将与靶向互补生物途径的抗淋巴瘤药物协同作用。目前的提案将利用PUH71独特的生物化学特性，并将其用作诱饵，以在蛋白质组学测定中鉴定DLBCL中的致癌Hsp90客户蛋白，再加上功能验证研究。第二种方法将探索一系列原代人DLBCL对PUH71的反应，并使用表达谱和生物信息学工具来鉴定有助于使DLBCL生物依赖于Hsp90的基因途径。然后，我们将使用这些信息来设计用于治疗DLBCL的组合靶向治疗方案。该提案将提供有关Hsp90在淋巴瘤中功能的机制信息，并将提供新的治疗方案和生物标志物用于DLBCL患者的测试。

DESCRIPTION (provided by applicant): Our proposal explores the molecular pathogenesis and therapeutic targeting of diffuse large B-cell lymphomas (DLBCL), which are the most common form of non-Hodgkin's lymphoma. Since these tumors are markedly heterogeneous, we are interested in identifying mechanisms relevant to the broadest cross-section possible of DLBCL patients. A recent report suggested that heat shock protein 90 (Hsp90) is widely expressed in DLBCL. We independently confirmed and validated this result and showed that Hsp90 binds and protects from degradation the BCL6 transcriptional repressor and the NEMO subunit of the IKK complex, both of which are components of oncogenic pathways in DLBCL. Several groups have developed Hsp90 inhibitors. However, most of these molecules have a relatively narrow therapeutic window that makes it impossible to fully suppress tumor Hsp90 in vivo. The Chiosis laboratory developed a purine scaffold inhibitor of Hsp90 called PUH71. PUH71 more potently and specifically binds the fraction of Hsp90 that chaperones oncogenic client proteins within tumor cells vs. other Hsp90 inhibitors and readily kills DLBCL cells in vitro and in vivo. A single dose of PUH71 administered to mice remained in lymphomas for over 48 hours at therapeutic levels, but rapidly cleared from normal tissues in just a few hours. Accordingly, PUH71 exhibited a wider therapeutic window and thus greater anti-DLBCL efficacy than other Hsp90 inhibitors. Given these promising results, the National Cancer Institute Division of Cancer Treatment and Diagnosis is sponsoring the translation of PUH71 for use in clinical trials. Altogether, our preliminary mechanistic and pre-clinical data lead us to hypothesize that Hsp90 is a critical therapeutic target in a broad cross-section of DLBCLs and that DLBCLs become addicted to Hsp90 since it protects from degradation components of multiple pathways involved in the survival of DLBCL across its various subtypes. Given its superior pharmacologic properties, we predict that PUH71 will be a highly active in primary human DLBCL and will synergize with anti-lymphoma drugs that target complementary biological pathways. The current proposal will take advantage of the unique biochemical properties of PUH71 and use it as a bait to identify oncogenic Hsp90 client proteins in DLBCL in proteomics assays, coupled with functional validation studies. A second approach will explore the response of a spectrum of primary human DLBCLs to PUH71 and use expression profiling and bio-informatic tools to identify gene pathways that contribute to making DLBCLs biologically dependent on Hsp90. We will then use this information to design combinatorial-targeted therapy regimens for the treatment of DLBCL. This proposal will deliver mechanistic information concerning the functions of Hsp90 in lymphomas, and also will deliver new therapeutic regimens and biomarkers for testing in DLBCL patients.