Colon Cancer Prevention with Phospho-Sulindac

描述(申请人提供)：联合化学预防的一个重大进展是使用舒林酸和二氟甲基鸟氨酸(DFMO)，最近被证明可以将所有人类结肠腺瘤的复发率降低69%，晚期腺瘤的复发率降低92%。DFMO抑制鸟氨酸脱羧酶，而鸟氨酸脱羧酶催化多胺合成的限速步骤，而舒林酸刺激多胺乙酰化和输出。最终结果是多胺水平降低，导致癌细胞生长受到抑制。然而，舒林酸有显著的副作用：胃肠道(20%)、中枢神经系统(10%)、皮疹和瘙痒(5%)以及肝酶升高。因此，有必要开发更安全和更有效的制剂。我们合成了一种新型的舒林酸衍生物--磷酸舒林酸，其抑制人结肠癌细胞生长的能力是常规舒林酸的14倍以上，体外毒理学评价和动物实验表明，它比常规舒林酸安全得多。我们的假设得到了初步数据的支持，即磷酸舒林酸是一种有效和安全的化学预防药物，可以与DFMO联合用于预防结肠癌，并且这种联合优于使用传统舒林酸的药物。为了评估这一假说并阐明相关机制，我们提出了三个具体目标：1)评估与化学预防相关的磷酸舒林酸的体外性质：效力、与DFMO的协同作用以及对细胞动力学的影响。2)确定磷酸-舒林酸的作用机制，重点是对化学预防药物作用的关键早期介质--活性氧(ROS)的影响，以及对包括多胺在内的依赖信号通路的影响。3)在小鼠结肠癌动物模型(小鼠和异种移植瘤)中，确定磷酸果酸联合DFMO对肠道癌变的影响，并在这些动物模型中验证关键的机制发现。这些目标将评估磷酸-舒林酸的药理作用的重要参数；探索其作用机制；并为其临床前的全面评估奠定基础，这是人类应用所需的。

DESCRIPTION (provided by applicant): A significant development in combination chemoprevention is the use of sulindac plus difluoromethylornithine (DFMO), which was recently demonstrated to reduce the recurrence of all human colon adenomas by 69% and of advanced adenomas by 92%. DFMO inhibits ornithine decarboxylase, which catalyzes the rate-limiting step in polyamine synthesis, while sulindac stimulates polyamine acetylation and export. The end result is reduced polyamine levels leading to suppressed growth of cancer cells. Sulindac, however, has significant side effects: gastrointestinal (20%); CNS (10%), skin rash and pruritus (5%), and elevations of hepatic enzymes. Thus there is a need to develop safer and more effective agents. We have synthesized phospho-sulindac, a novel derivative of sulindac, that is over >14-fold more potent than conventional sulindac in inhibiting the growth of human colon cancer cells, and appears much safer than conventional sulindac based on in vitro toxicological evaluation and animal studies. Our hypothesis, supported by preliminary data, is that phospho-sulindac is an effective and safe chemopreventive agent that can be combined with DFMO for the prevention of colon cancer and that such combination is superior to the one using conventional sulindac. To evaluate this hypothesis and delineate the relevant mechanisms, we propose three specific aims: 1) Evaluate in vitro properties of phospho-sulindac that are relevant to chemoprevention: potency, synergy with DFMO and effect on cytokinetics. 2) Determine the mechanism of action of phospho-sulindac focusing on its effect on reactive oxygen species (ROS), key early mediators of the effect of chemopreventive agents, and on dependent signaling pathways including polyamines. 3) Determine in animal models of colon cancer (Min mice and xenografts) the effect of phosphosulindac plus DFMO on intestinal carcinogenesis and verify in these animal models key mechanistic findings. These aims will assess important parameters of the pharmacological action of phospho-sulindac; explore its mechanism of action; and set the stage for its thorough preclinical evaluation that is required for its human application.