Small Molecule Activators of Procaspases as Anti-Cancer Agents

描述（由申请人提供）：本文提出的工作的广泛、长期目标是验证抗癌治疗的新策略。癌细胞的一个标志是它们能够抵抗细胞凋亡并变得不朽。这种抗性通常是由于凋亡级联中多种蛋白质的突变或异常表达。这些改变是凋亡回路中的有效“中断”，其阻止促凋亡信号被传递以将半胱天冬酶原-3活化为半胱天冬酶-3。Caspase-3是负责数百种细胞底物的蛋白水解的主要“刽子手”caspase。有趣的是，procaspase-3水平在多种癌症中升高，但有缺陷的凋亡机制根本无法激活这种酶原。本文描述了用小分子直接将半胱天冬酶原-3活化为活性半胱天冬酶-3的抗癌策略。在令人兴奋的初步结果中，我们通过高通量筛选，确定了一种procaspase-3激活化合物，我们称之为PAC-1。在细胞培养中，PAC-1诱导凋亡性细胞死亡，其效力与细胞中存在的半胱天冬酶原-3的量成正比。PAC-1还强烈诱导来自原发性结肠肿瘤的细胞中的凋亡性死亡，其效力严格依赖于细胞中的半胱氨酸天冬氨酸蛋白酶原-3的量。我们已经证明PAC-1在三种不同的癌症小鼠模型中具有活性。在拟议的工作中，我们将使用PAC-1的这一发现作为跳板来探测凋亡途径，评估PAC-1及其衍生物在小鼠中的药代动力学、疗效和毒性，并阐明PAC-1激活半胱氨酸天冬氨酸蛋白酶原-3的生化机制。公共卫生相关性。癌症现在已经超过心脏病，成为美国的主要死因，是一个巨大的公共卫生问题。基本细胞死亡机制的突变使癌细胞能够抵抗自然防御和化疗治疗。我们提出了一种策略，通过这种策略，我们将完全绕过突变的电路并激活癌细胞中的死亡途径，从而杀死癌症并挽救患者的生命。

DESCRIPTION (provided by applicant): The broad, long-term objective of the work proposed herein is to validate a novel strategy for anti-cancer therapy. A hallmark of cancerous cells is their ability to resist apoptosis and become immortal. This resistance is typically due to mutations in or aberrant expression of a wide variety of proteins in the apoptotic cascade. These alterations are effectively "breaks" in the apoptotic circuitry, which prevent proapoptotic signals from being transmitted to activate procaspase-3 to caspase-3. Caspase-3 is the major "executioner" caspase that is responsible for the proteolysis of hundreds of cellular substrates. Interestingly, procaspase-3 levels are elevated in a variety of cancers, but the defective apoptotic machinery simply cannot activate this zymogen. Described herein is an anti-cancer strategy to directly activate, with a small molecule, procaspase-3 to active caspase-3. In exciting preliminary results we have, through high-throughput screening, identified a procaspase-3 activating compound that we call PAC-1. In cell culture, PAC-1 induces apoptotic cell death, and its potency is directly proportional to the amount of procaspase-3 present in the cell. PAC-1 also powerfully induced apoptotic death in cells from primary colon tumors, with a potency strictly dependent on the amount of procaspase-3 in the cells. We have shown PAC-1 to be active in three different mouse models of cancer. In the proposed work we will use this discovery of PAC-1 as a springboard to probe the apoptotic pathways, evaluate the pharmacokinetics, efficacy, and toxicity of PAC-1 and derivatives in mice, and elucidate the biochemical mechanism by which PAC-1 activates procaspase-3. Public health relevance. Cancer has now overtaken heart disease as the leading cause of death in the U.S and is an enormous public health problem. Mutations in the fundamental cell death machinery enable cancerous cells to resist natural defenses and chemotherapeutic treatments. We propose a strategy by which we will completely bypass the mutated circuitry and activate the death pathway in cancer cells, thus killing the cancer and saving the life of the patient.