Chemoprevention Potential of Calpain Inhibitors

描述（由申请人提供）： 长期目标是开发钙蛋白酶抑制剂作为一类新的化学预防剂。已知早期癌前细胞比晚期癌前细胞更容易凋亡。这种改变对细胞凋亡敏感性的机制可能对癌的发生和化学预防剂的发展具有重要意义。钙蛋白酶在多种肿瘤中过度表达，许多凋亡调节蛋白是钙蛋白酶的底物，表明钙蛋白酶在癌症中具有重要的调节作用。最近的研究还表明，钙蛋白酶在促进细胞转化和细胞迁移中的作用可能在癌症病理生物学的背景下具有重要的体内后果。因此，本申请的直接目标是验证钙蛋白酶作为发现新型化学预防剂的药理学靶点。我们的中心假设是“抑制钙蛋白酶活性将预防或延缓癌前病变的进展以及癌细胞侵袭”。我们将通过以下具体目标来研究这一假设：1）合成选择性作为代谢稳定的钙蛋白酶抑制剂的α-酮酰胺，并使用它们来验证钙蛋白酶作为化学预防靶点; 2）确定钙蛋白酶和凋亡调节蛋白的表达水平（p53、Bcl-2和Bax）在早期和晚期癌前细胞中的表达;和3）测定钙蛋白酶抑制剂在体外预防或延缓癌前细胞进展和限制癌细胞侵袭的能力。将分析将产生的数据以确定（a）细胞内钙蛋白酶抑制和用钙蛋白酶抑制剂处理癌前细胞后凋亡细胞的百分比之间是否存在联系;（B）细胞内钙蛋白酶抑制和钙蛋白酶抑制剂在癌前细胞中诱导的细胞毒性之间是否存在联系;（c）细胞内钙蛋白酶抑制和钙蛋白酶抑制剂对癌细胞侵袭的阻滞之间是否存在联系。强相关性将使钙蛋白酶抑制剂的内在效力与这些参数中的每一个相关联，并通过生物靶标（即钙蛋白酶）确认化合物的活性。该提案是重要的和创新的，因为它试图调查钙蛋白酶作为一个药理学目标，发现一类新的化学预防剂。

DESCRIPTION (provided by applicant): The long-term goal is to develop calpain inhibitors as a new class of chemoprevention agents. Early precancerous cells are known to be more susceptible to apoptosis than late stage precancerous cells. The mechanism involved in this altered susceptibility to apoptosis could have important implications for carcinogenesis and the development of chemoprevention agents. Calpain is over expressed in several tumors and a number of apoptosis regulating proteins are calpain substrates suggesting an important regulatory role of calpain in cancer. Recent studies also suggest that the role of calpain in promoting cell transformation and cell migration may have important in vivo consequences in the context of cancer pathobiology. Therefore, the immediate goal of this application is to validate calpain as a pharmacological target for the discovery of novel chemoprevention agents. Our central hypothesis is "inhibition of calpain activity will prevent or retard progression of precancerous lesions as well as cancer cell invasion". We will investigate this hypothesis by addressing the following specific aims: 1) synthesize alpha-ketoamides selective as metabolically stable calpain inhibitors and use them to validate calpain as a chemoprevention target; 2) determine the expression levels of calpain and apoptosis regulating proteins (p53, Bcl-2, and Bax) in early and late stage precancerous cells; and 3) determine the ability of the calpain inhibitors to prevent or retard progression of precancerous cells and to limit cancer cell invasion in vitro. The data that will be generated will be analyzed to determine if there is a link between (a) intracellular calpain inhibition and the percentage of apoptotic cells following treatment of the precancerous cells with the calpain inhibitors; (b) intracellular calpain inhibition and cytotoxicity induced in the precancerous cells by the calpain inhibitors; (c) intracellular calpain inhibition and retardation of cancer cell invasion by the calpain inhibitors. Strong correlations will associate the intrinsic potency of the calpain inhibitors with each of these parameters and confirm the activity of the compounds through a biological target, namely calpain. The proposal is significant and innovative because it seeks to investigate calpain as a pharmacological target for the discovery of a new class of chemoprevention agents.