Prostate Cancer Prevention by Diallyl Trisulfide

描述（由申请人提供）：由于美国男性中与这种恶性肿瘤相关的高死亡率，因此非常需要预防前列腺癌的新策略。在该资助的资助期间，我们发现大蒜成分二烯丙基三硫化物（DATS）通过引起细胞凋亡而选择性地抑制培养的人前列腺癌细胞的生长，而不管其雄激素反应性或p53状态如何。我们还首次证明，口服DATS给药不仅可以延缓无胸腺小鼠中PC-3人前列腺癌异种移植物的生长，而且还可以在转基因小鼠模型（TRAMP）中提供显著的保护作用，防止前列腺癌的发展，而没有任何明显的毒性迹象。此外，我们发现，DATS介导的前列腺癌细胞中的促凋亡信号转导与由于铁蛋白（轻链）降解和不稳定（可螯合）铁库增加而产生的活性氧（ROS）密切相关。我们最近的初步未发表的研究表明，治疗人前列腺癌细胞的凋亡诱导浓度的DATS的结果在上调生存素，抗凋亡蛋白经常在人类癌症中过表达。目前的更新申请，建立在这些令人兴奋的和新的观察，在很大程度上转移重点从分子导向的细胞研究，在体内验证的机制，具有巨大的翻译价值的发现。假设：统一更新申请的特定目的的中心假设是，有利的药代动力学属性使DATS能够通过不稳定的铁-ROS介导的细胞凋亡来预防前列腺癌的发展，这可以通过对存活素的药理学抑制来增强。具体目标：更新申请的具体目的是：（1）使用非转基因雄性小鼠确定DATS的药代动力学参数和口服生物利用度;（2）使用细胞免疫学方法确定不稳定铁介导的ROS产生在对DATS的促凋亡和化学预防反应中的贡献。（PC-3、LNCaP和PrEC）和体内模型（TRAMP小鼠）;（3）使用培养的细胞，深入了解ROS产生下游DATS诱导的细胞凋亡的分子回路（4）使用细胞（PC-3、LNCaP）和体内模型（TRAMP小鼠）确定存活素敲低对促凋亡和对DATS的化学预防应答的影响。拟议研究的转化影响：尽管在本项目资助期间进行的研究为DATS对前列腺癌的疗效提供了令人信服的临床前证据，但将这些发现有效转化为临床环境关键取决于细胞观察结果的体内验证。临床试验没有充分了解影响DATS生物学效应的因素，会有失败的风险。例如，体内验证不稳定的铁-ROS在对DATS的促凋亡和化学预防应答中的贡献（具体目标2）对于优化基于DATS的化学预防方案以消除DATS与其他抗氧化剂或干扰铁稳态的试剂之间的潜在不良药物-药物相互作用是必不可少的。类似地，特异性目标4的内在价值在于涉及DATS和存活素抑制剂的组合方案的潜在设计，用于人前列腺癌的有效化学预防。 公共卫生相关性：前列腺癌是最常诊断的内脏恶性肿瘤之一，也是美国男性癌症相关死亡的主要原因。因此，非常需要阻止前列腺癌的发生和/或进展的新策略，以降低与这种肿瘤相关的疾病相关成本、发病率和死亡率。本项目的最终目标是开发一种安全，廉价，但有效的策略，使用大蒜成分二烯丙基三硫化物（DATS）的人类前列腺癌的化学预防。尽管迄今为止进行的研究为DATS对前列腺癌的疗效提供了令人信服的临床前证据，但将这些发现有效转化为临床环境关键取决于细胞发现的体内验证。总之，本更新申请中提出的研究的近期和未来内在价值在于优化基于DAT的前列腺癌化学预防方案。

DESCRIPTION (provided by applicant): Novel strategies for prevention of prostate cancer are highly desirable because of high mortality associated with this malignancy in American men. During the funded period of this grant, we showed that garlic constituent diallyl trisulfide (DATS) selectively inhibits growth of cultured human prostate cancer cells by causing apoptosis regardless of their androgen responsiveness or the p53 status. We also demonstrated, for the first time, that oral DATS administration not only retards growth of PC-3 human prostate cancer xenografts in athymic mice but also offers significant protection against prostate cancer development in a transgenic mouse model (TRAMP) without any signs of overt toxicity. Furthermore, we discovered that the DATS-mediated proapoptotic signal transduction in prostate cancer cells is intimately linked to the production of reactive oxygen species (ROS) due to ferritin (light chain) degradation and an increase in labile (chelatable) iron pool. Our more recent preliminary unpublished studies have revealed that treatment of human prostate cancer cells with apoptosis-inducing concentrations of DATS results in up-regulation of survivin, an anti-apoptotic protein frequently overexpressed in human cancers. The present renewal application, building upon these exciting and novel observations, largely shifts emphasis from molecularly-oriented cellular studies to in vivo validation of the mechanistic findings with tremendous translational value. Hypothesis: Central hypothesis unifying the specific aims of the renewal application is that favorable pharmacokinetic attributes empower DATS to prevent prostate cancer development via labile iron-ROS- mediated apoptosis, which is amenable to augmentation by pharmacologic suppression of survivin. Specific Aims: The specific aims of the renewal application are to: (1) determine the pharmacokinetic parameters and oral bioavailability of DATS using non-transgenic male mice; (2) determine the contribution of labile iron-mediated ROS production in proapoptotic and chemopreventive response to DATS using cellular (PC-3, LNCaP, and PrEC) and in vivo models (TRAMP mice); (3) gain insight into the molecular circuitry of DATS-induced apoptosis downstream of ROS production using cultured cells (PC-3, LNCaP, and PrEC) and prostate/tumor tissues from TRAMP mice (from specific aim 2); and (4) determine the effect of survivin knockdown on proapoptotic and chemopreventive response to DATS using cellular (PC-3, LNCaP) and in vivo models (TRAMP mice). Translational Impact of the Proposed Research: Even though the studies conducted during the funded period of this project provide compelling preclinical evidence for efficacy of DATS against prostate cancer, efficient translation of these findings into a clinical setting is critically dependent on in vivo validation of the cellular observations. Clinical trials without a full appreciation of the factors influencing biological effects of DATS inherit risk of failure. For example, in vivo validation of the contribution of labile iron-ROS in proapoptotic and chemopreventive response to DATS (Specific Aim 2) is essential for optimization of DATS-based chemopreventive regimens to eliminate potential adverse drug-drug interactions between DATS and other anti- oxidants or agents interfering with iron homeostasis. Similarly, intrinsic value of Specific Aim 4 resides in potential design of combination regimens involving DATS and inhibitors of survivin for efficient chemoprevention of human prostate cancer. PUBLIC HEALTH RELEVANCE: Prostate cancer is one of the most commonly diagnosed visceral malignancies and a leading cause of cancer- related deaths among men in the United States. Therefore, novel strategies to hinder inception and/or progression of prostate cancer are highly desirable to reduce the disease-related cost, morbidity and mortality associated with this neoplasm. The ultimate goal of this project is to develop a safe and inexpensive but effective strategy for chemoprevention of human prostate cancer using garlic constituent diallyl trisulfide (DATS). Even though the studies conducted thus far provide compelling preclinical evidence for efficacy of DATS against prostate cancer, efficient translation of these findings into a clinical setting is critically dependent on in vivo validation of the cellular findings. In summary, the immediate and future intrinsic value of the studies proposed in this renewal application resides in optimization of DATS-based regimens for chemoprevention of prostate cancer.