Chaetocin as a Potential Therapy for Multiple Myeloma

项目摘要 多发性骨髓瘤是一种致命的浆细胞癌，在美国每年导致超过11,000人死亡。 独自一人。目前还没有治愈方法，迫切需要改进的治疗方法。 我们最近发现毛霉素，一种以前没有报道的天然产品，具有抗肿瘤作用。 抗癌作用，在体外、体内外均有较强的抗骨髓瘤活性和选择性。令人印象深刻的是， 在对地塞米松或阿霉素耐药的骨髓瘤中，毛霉素有抗骨髓瘤作用 细胞和患者中的骨髓瘤样本收集自大量预治疗的患者，这些患者含有不同的 细胞遗传学改变。从机理上讲，毛霉素会在癌细胞中迅速而戏剧性地积聚， 需要完整/未还原的二硫化物来摄取，并施加ROS来进行细胞毒选择性。此外，我们 最近证实毛壳素是ROS缓解的竞争性底物(和抑制剂) 硫氧还蛋白还原酶(TrxR)在达到细胞内浓度时-导致我们的假设 TrxR可能是毛壳素的一个细胞毒性分子靶点。从整体上看，毛壳素似乎 作为一种潜在的抗骨髓瘤治疗药物，具有广阔的应用前景。 在取得令人鼓舞的初步成果的基础上，我们现在提出以下具体目标： 目的1：进一步评价毛壳素诱导的细胞毒性、细胞摄取和 积累。我们将严格评估TrxR和其他还原酶、组蛋白的作用 修饰酶(包括HDAC和HMT)、HIF1和其他靶点以选择性细胞毒 以及进一步研究细胞内毛黄素摄取和积累的机制。 目的2：通过系统的差异探索，进一步阐明毛壳素的细胞毒性选择性 ROS通路在骨髓瘤细胞中的功能。我们将进一步定义正常和正常情况下毛细辛素的选择性。 恶性血液病细胞，并与Aim1的机制研究密切配合，探索 通过阐述ROS和其他酶的不同活性来观察细胞毒选择性的分子基础 成对毛壳素敏感/耐药患者细胞和骨髓瘤细胞系中的通路。 目的3：进一步评价毛壳素的体内毒性和疗效。我们将在体内进行优化 在异种移植和系统性骨髓瘤模型中进行配方和进行毒理学、PK、PD和疗效研究； 以及初步探索基于目标1的机理研究而形成的体内生物标记物。 总而言之，拟议中的实验将促进对毛壳素细胞效应的理解， 促进其进一步发展，并提供重要的见解，以了解是否有其他类似的诱因 ROS也可能是作为抗骨髓瘤治疗药物进一步开发的有吸引力的候选药物。项目叙事 多发性骨髓瘤是一种致命的骨髓癌，在美国每年导致超过11,000人死亡。 孤独；没有治愈方法，迫切需要改进的治疗方法。我们最近发现， 毛壳素，一种从一种常见的木材霉菌中分离出来的物质，以前没有报道过具有抗癌作用， 在癌细胞系、患者骨髓瘤细胞和动物体内具有有效和选择性的抗骨髓瘤活性 骨髓瘤模型。我们现在建议对毛壳素进行进一步研究，以更好地确定其作用机制 在动物模型中的作用、癌症选择性和治疗骨髓瘤的能力，希望最终发展成 毛壳素作为治疗骨髓瘤患者的一种方法。

Project Summary Multiple myeloma is a uniformly fatal plasma cell cancer that kills over 11,000 individuals annually in the U.S. alone. No cure exists, and improved therapies are desperately needed. We have recently discovered that chaetocin, a natural product previously unreported to have anti- cancer effects, has potent and selective in vitro, ex vivo and in vivo anti-myeloma activity. Impressively, the anti-myeloma effects of chaetocin are maintained in dexamethasone- or doxorubicin-resistant myeloma cells and in patient myeloma samples collected from heavily pre-treated patients harboring a diverse array of cytogenetic alterations. Mechanistically, chaetocin is rapidly and dramatically accumulated in cancer cells, requiring intact/unreduced disulfides for uptake, and imposition of ROS for cytotoxic selectivity. Moreover, we have recently established that chaetocin is a competitive substrate for (and inhibitor of) the ROS mitigation enzyme thioredoxin reductase (TrxR) at achieved intracellular concentrations - leading to our hypothesis that TrxR may represent a cytotoxic molecular target of chaetocin. Considered collectively, chaetocin appears to represent a promising agent for further development as a potential anti-myeloma therapeutic. Based upon encouraging preliminary results, we now propose the following specific aims: Aim 1: Further evaluation of the mechanisms of chaetocin-induced cytotoxicity, cellular uptake and accumulation. We will critically evaluate the contributions of effects on TrxR and other reductases, histone modifying enzymes (including HDACs and HMTs), HIF1 and other targets to the cytotoxic selectivity of chaetocin; as well as further investigate mechanisms of cellular chaetocin uptake and accumulation. Aim 2: Further clarification of the cytotoxic selectivity of chaetocin with systematic exploration of differential functions of ROS pathways in myeloma cells. We will further define the selectivity of chaetocin in normal vs. malignant hematological cells and, in close coordination with mechanistic studies in Aim1, probe the molecular basis of observed cytotoxic selectivity through elaboration of differential activities of ROS and other pathways in paired chaetocin sensitive/resistant patient cells and myeloma cell lines. Aim 3: Further evaluation of the in vivo toxicities and efficacy of chaetocin. We will optimize in vivo formulations and conduct toxicology, PK, PD, and efficacy studies in xenograft and systemic myeloma models; as well as preliminarily explore in vivo biomarkers formulated based upon mechanistic studies of Aim 1. Collectively, proposed experiments will advance understanding of the cellular effects of chaetocin, foster its further development, and provide important insights into whether other agents that similarly induce ROS may also represent attractive candidates for further development as anti-myeloma therapeutics. Project Narrative Multiple myeloma is a uniformly fatal bone marrow cancer that kills over 11,000 individuals annually in the U.S. alone; no cure exists, and improved therapies are desperately needed. We have recently discovered that chaetocin, a substance isolated from a common wood mold previously unreported to have anti-cancer effects, has potent and selective anti-myeloma activity in cancer cell lines, patient myeloma cells and in an animal model of myeloma. We now propose further studies of chaetocin intended to better define its mechanisms of action, cancer selectivity, and ability to treat myeloma in animal models in hopes of eventually developing chaetocin as a therapy for patients afflicted with myeloma.