HDAC6-Selective Inhibitors for Pancreatic Cancer Treatment

描述(申请人提供)：胰腺癌是美国第五大癌症死亡原因。尽管为了解其分子生物学做出了巨大努力，但常规治疗效果甚微。由于这种疾病的高度转移性，只有15%-20%的患者可以进行手术。因此，迫切需要开发和表征能够单独或与传统疗法一起使用的新的治疗剂。有4种类型的HDAC，推测癌细胞中HDAC活性的增加可能有助于p16、p21和明胶蛋白等抑癌基因的表观遗传沉默。事实上，用广谱的Classi/II类HDAC抑制剂(HDACi)SAHA处理胰腺癌细胞，会导致p21表达上调，抑制生长并诱导细胞凋亡。UIC的Kozikowski教授的团队最近创造了新的HDACI类别，其中几种在体外对HDAC6和HDAC3显示出低PM活性。用这些化合物处理胰腺癌细胞，会导致G1和/或G2期停滞，并诱导细胞凋亡。此外，数据表明，这些新的HDACI中的一些会导致DNA损伤检查点激酶Chk1的丢失。据推测，它们可以使胰腺肿瘤细胞对基因毒性药物敏感。我们相信，将这些HDACI与DNA损伤诱导剂(如吉西他滨)相结合，将比仅用吉西他滨常规治疗提供显著的治疗益处。为了验证这一假设，我们建议(1)重新合成UIC生产的12个最活跃的HDACIs，并合成10个新的类似物并测试它们的异构体选择性；(2)确定HDACIs在体外对胰腺肿瘤细胞增殖和存活的生物学作用；(3)确定5个最好的HDACIs在联合吉西他滨治疗已建立的胰腺癌细胞株异种移植瘤中的体内疗效。这些研究将提供有关HDACIs与导致DNA损伤的治疗剂联合使用的重要信息，以及与这些化合物在胰腺癌治疗中的安全性和有效性相关的有价值的结构-活性关系(SAR)数据，同时允许衡量在寻找“安全”治疗方法时需要异构体选择性的程度。这里提出的HDACI的生物学特性也可以允许更好地将特定的异构体与致瘤事件联系起来。在这个第一阶段提案中确定的两到三个最好的HDACI将成为第二阶段申请的主题，以资助旨在推动这些化合物之一进入临床研究的ADMET工作。公共卫生相关性：胰腺癌是美国第五大癌症死亡原因，常规化疗很难治愈，而由于这种疾病的高度转移性，只有15%-20%的患者可以进行手术。本研究旨在研究一系列新型组蛋白脱乙酰酶(HDAC)抑制剂与常规化疗药物吉西他滨联合应用对小鼠胰腺癌细胞异种移植瘤生长的抑制作用。积极的结果将导致第二阶段的申请，以资助旨在推动这些化合物之一进入临床研究的ADMET工作。

DESCRIPTION (provided by applicant): Pancreatic cancer is the fifth leading cause of cancer death in the US. Despite tremendous efforts aimed at understanding its molecular biology, conventional treatment has had little impact. Due to the highly metastatic nature of the disease, surgery is available to only 15- 20% of patients. Thus, the development and characterization of new therapeutic agents that can be used alone or together with conventional therapies is desperately needed. There are 4 classes of HDACs, and it is hypothesized that increased HDAC activity in cancer cells may contribute to the epigenetic silencing of tumor suppressor genes such as p16, p21 and gelsolin. In fact, treatment of pancreatic cancer cells with the broad spectrum classI/II HDAC inhibitor (HDACI), SAHA, leads to upregulation of p21, growth inhibition and induction of apoptosis. The team of Professor Kozikowski at UIC has recently generated novel classes of HDACIs, several of which show low pM activity toward HDAC6 and HDAC3 in vitro. Treatment of pancreatic cancer cells with these compounds results in a G1 and/or G2 arrest and induction of apoptosis. In addition, the data indicate that some of these novel HDACIs cause loss of the DNA damage checkpoint kinase, Chk1. It is hypothesized that they can sensitize pancreatic tumor cells to genotoxic agents. We believe that a combination of these HDACIs with DNA damage-inducing agents, such as gemcitabine, will provide significant therapeutic benefit compared to the conventional treatment, gemcitabine alone. To test this hypothesis, we propose to (1) re-synthesize the 12 most active HDACIs made at UIC, and to synthesize 10 new analogs and test them for isoform selectivity; (2) to define biological effects of HDACIs on pancreatic tumor cell proliferation and survival in vitro; and (3) to determine the in vivo efficacy of the 5 best HDACIs on established pancreatic tumor cell line xenografts with co-administration of gemcitabine. These studies will provide important information regarding the use of HDACIs in combination with therapeutic agents that cause DNA damage, and valuable structure-activity relationship (SAR) data relevant to the safety and efficacy of these compounds in the treatment of pancreatic cancer, while allowing to gauge the extent to which isoform selectivity is required in finding a "safe" therapy. The biological characterization of the HDACIs presented herein may also allow to better link specific isoforms to tumorigenic events. The two or three best HDACIs identified in this Phase I proposal will be the subject of a Phase II application to fund ADMET work aimed at advancing one of these compounds into clinical studies. PUBLIC HEALTH RELEVANCE: Pancreatic cancer is the fifth leading cause of cancer death in the US and is poorly treatable by conventional chemotherapy, while surgery is available to only 15-20% of patients due to the highly metastatic nature of the disease. The present application aims at investigating the ability of a novel series of inhibitors of histone deacetylases (HDACs), which have been shown to inhibit pancreatic cancer cell growth in vitro and lead to apoptosis, to inhibit the growth of pancreatic tumor cell line xenografts in mice in combination with the conventional chemotherapeutic agent, gemcitabine. Positive results would lead to a Phase II application to fund ADMET work aimed at advancing one of these compounds into clinical studies.