Therapeutic targeting of stratifin structure and function

描述(申请人提供)：对化疗和/或放射诱导的细胞凋亡缺乏反应是成功治疗人类癌症(如胰腺癌)的主要问题。最近，我们发现在一系列对药物诱导的凋亡不敏感的药物选择的癌细胞系中，层蛋白的表达水平升高，并且其表达水平与这些细胞的药物敏感性水平呈负相关。ShRNA敲除和增强异位表达均证实了层蛋白表达与药物不敏感之间的因果关系。我们研究的长期目标是了解药物和/或辐射诱导胰腺癌细胞凋亡的分子机制，并使癌细胞对这些治疗诱导的细胞凋亡敏感。本研究的近期目标是探讨层翅素在细胞对药物或辐射诱导的细胞凋亡反应中的作用，并以层翅素为靶点进行药物发现，以增强胰腺癌细胞对治疗的反应。这项研究中要检验的假设是，胰腺癌细胞中层纤蛋白的高表达通过结合和影响重要的生存蛋白质来降低细胞对药物或辐射诱导的凋亡的反应，并且这种作用可以通过使用小分子抑制剂靶向层纤蛋白来逆转。为此，将实现四个特定的目标：(1)确定层翅蛋白表达增加是否也导致细胞对辐射诱导的凋亡的反应降低；(2)确定层翅蛋白表达增加是否调节Chk2，后者反过来调节DNA修复和生存的细胞周期检查点；(3)确定二聚作用的机制以及是否需要二聚化作用；以及(4)发现和测试针对层翅蛋白二聚作用的小化合物以进行化学增敏。印第安纳大学布伦和梅尔文·西蒙癌症中心优越的科学环境，首席研究员在研究药物诱导的细胞凋亡反应方面的丰富经验，以及慷慨的机构支持，将极大地有助于该项目的成功。从本研究中获得的信息和探针将有助于我们理解层状蛋白在肿瘤化疗中的细胞凋亡中的作用。这项工作还将使我们发现可能有助于使癌症对药物和放射治疗敏感的治疗剂，以及用于研究蛋白质-蛋白质相互作用的探针。 公共卫生相关性：对化疗和放射治疗诱导的细胞凋亡缺乏反应是人类胰腺癌化疗成功的主要问题。我们研究的长期目标是了解药物和/或辐射诱导癌症细胞凋亡的分子机制，并使癌细胞对这些治疗诱导的细胞凋亡敏感。这项研究中要检验的假设是，胰腺癌细胞中层纤蛋白的高表达通过结合和影响重要的生存蛋白质来降低细胞对药物或辐射诱导的凋亡的反应，并且这种作用可以通过使用小分子抑制剂靶向层纤蛋白来逆转。为此，将实现四个特定的目标：(1)确定层翅蛋白表达增加是否也导致细胞对辐射诱导的凋亡的反应降低；(2)确定层翅蛋白表达增加是否调节Chk2，后者反过来调节DNA修复和生存的细胞周期检查点；(3)确定二聚作用的机制以及是否需要二聚化作用；以及(4)发现和测试针对层翅蛋白二聚作用的小化合物以进行化学增敏。

DESCRIPTION (provided by applicant): Lack of response to chemo and/or radiation-induced apoptosis is a major problem for successful therapy of human cancers such as pancreatic cancer. Recently, we found that the expression of stratifin is elevated in a series of drug-selected cancer cell lines that are less sensitive to drug-induced apoptosis and its expression level negatively correlates with the drug sensitivity level of these cells. Knocking-down with shRNA and enforced ectopic expression of stratifin both confirmed the cause-effect relationship between stratifin expression and drug insensitivity. The long-term goal of our study is to understand the molecular mechanisms of drug and/or radiation-induced apoptosis in pancreatic cancers and to sensitize cancer cells to these treatment-induced apoptosis. The immediate goal of this study is to investigate the role of stratifin in cellular response to drug or radiation-induced apoptosis and to target stratifin for drug discovery to enhance the response of pancreatic cancer cells to therapeutic treatment. The hypotheses to be tested in this study are that the elevated expression of stratifin in pancreatic cancer cells decreases cellular response to drug or radiation-induced apoptosis by binding to and affecting important proteins for survival and that this effect can be reversed by targeting stratifin using small molecule inhibitors. To this end, four specific aims will be accomplished: (1) to determine if increased stratifin expression also causes decrease in cellular response to radiation-induced apoptosis; (2) to determine if increased stratifin expression regulates Chk2 which, in turn, regulates cell cycle checkpoint for DNA repair and survival; (3) to determine the mechanism of dimerization and if the dimerization is required for the function of stratifin; and (4) to discover and test small chemical compounds targeting stratifin dimerization for chemosensitization. The excellent scientific environment at Indiana University Bren and Melvin Simon Cancer Center, the extensive experience of the principal investigator in studying cellular responses to drug- induced apoptosis, and the generous institutional support will contribute enormously to the likelihood of success of this project. The information and probes obtained from this study will help us understand the role of stratifin in apoptosis in cancer chemotherapy. This work will also lead us to the discovery of therapeutic agents that may help sensitize cancers to drug and radiation therapy and probes for investigating protein-protein interactions. PUBLIC HEALTH RELEVANCE: Lack of response to chemo and radiation treatment-induced apoptosis is a major problem for successful chemotherapy of human pancreatic cancers. The long-term goal of our study is to understand the molecular mechanisms of drug and/or radiation-induced apoptosis in cancers and to sensitize cancer cells to these treatment-induced apoptosis. The hypotheses to be tested in this study are that the elevated expression of stratifin in pancreatic cancer cells decreases cellular response to drug or radiation-induced apoptosis by binding to and affecting important proteins for survival and that this effect can be reversed by targeting stratifin using small molecule inhibitors. To this end, four specific aims will be accomplished: (1) to determine if increased stratifin expression also causes decrease in cellular response to radiation-induced apoptosis; (2) to determine if increased stratifin expression regulates Chk2 which, in turn, regulates cell cycle checkpoint for DNA repair and survival; (3) to determine the mechanism of dimerization and if the dimerization is required for the function of stratifin; and (4) to discover and test small chemical compounds targeting stratifin dimerization for chemosensitization.