Isozyme-selective ALDH Inhibitors for Sensitizing Ovarian Cancer Stem-like Cells to Chemotherapy

项目摘要：上皮性卵巢癌(EOC)的治愈率没有任何改善 在过去的30年里。在美国，每年约有21,400名女性被确诊，约15,000人将 患上致命的抗药性疾病。因此，克服化疗耐药性是一项关键的未得到满足的需求。一个目标 克服化疗耐药的是ALDH1A同工酶家族。ALDH1a同工酶在 卵巢癌细胞体内外化疗耐药及ALDH1A1基因敲除逆转化疗 抵抗。高度ALDH活性(ALDHbright)细胞可能与其在化疗耐药中的作用有关 作为肿瘤干细胞(CSC)。ALDHbright卵巢CSC对化疗耐药，肿瘤始发率增加 容量。实验上，靶向CSC的药物可以提高化疗疗效，逆转化疗。 抵抗治疗，防止癌症复发。因此，靶向ALDH1A同工酶可能具有 瞄准CSC的独特优势。事实上，我们的初步数据表明，一种新型的ALDH1A抑制剂673A(I) 与化疗协同杀死耐药的卵巢癌细胞，(Ii)选择性地杀死卵巢CSC， 从而降低肿瘤的起始能力，以及(Iii)在多种肿瘤模型中结合化疗 能够治愈约50%患有化疗耐药卵巢癌的动物。不幸的是，673A和其他类似物 临床开发的候选药物很差，因为它们代谢迅速和/或是共价的ALDH修饰剂。 我们最近发现了一系列新的有效的非共价、非底物ALDH1A抑制剂。 重要的是，我们的初步数据表明，这些新的ALDHi杀死CSC并与 化疗。ALDHi的同工酶选择性可以很容易地通过微小的结构变化来改变。这个 这项工作的首要目标是确定ALDH1A的同工酶选择性抑制是否会构成 安全有效的辅助治疗复发性卵巢癌对现有化疗增敏。 我们还将确定哪种ALDH1A同工酶抑制谱(S)是最有效的。我们建议：1) 根据我们的新化学系列优化ALDH1A抑制剂的效力和同工酶选择性，在 新的共晶体结构信息；2)确定哪些ALDH1A抑制剂最有效地耗尽卵巢 CSC的体外实验；3)评价最佳的药物动力学特性；以及4)选择最佳的探针用于 化疗耐药的小鼠卵巢癌移植瘤模型的评价。我们的建议在使用上是创新的 一种新的ALDH1A：抑制剂的共晶结构和同工酶结构设计的同源模型 选择性抑制剂，以及最终使用患者来源的带有人基质的异种移植物来更准确地 在临床上预测疗效。这项工作将对确定ALDH1A家族抑制是否可以 克服体内卵巢癌化疗耐药，以及哪种同工酶抑制谱最优。最后，我们的 针对复发性卵巢癌的有效辅助治疗将取得进展，这是一种可怕的 没有得到满足的医疗需求，因此产生重大影响的可能性很大。

PROJECT SUMMARY: There has been no improvement in the cure rate for epithelial ovarian cancer (EOC) for the past 30 years. Approximately 21,400 women in the U.S. are diagnosed annually, and ~15,000 will develop fatal chemoresistant disease. Thus, overcoming chemoresistance is a critical unmet need. One target to overcome chemoresistance is the ALDH1A family of isoenzymes. ALDH1A isoenzymes are upregulated in chemoresistant ovarian cancer cells in vitro and in vivo, and knockdown of ALDH1A1 reverses chemotherapy resistance. Potentially related to its role in chemotherapy resistance, highly ALDH-active (ALDHbright) cells can act as cancer stem-like cells (CSC). ALDHbright ovarian CSC are chemoresistant with increased tumor initiation capacity. Experimentally, agents targeting CSC can increase chemotherapeutic efficacy, reverse chemo- therapy resistance, and prevent cancer recurrences. Thus, targeting ALDH1A isoenzymes may have the unique benefit of targeting CSC. Indeed, our preliminary data suggests that a novel ALDH1A inhibitor 673A (i) synergizes with chemotherapy to kill chemoresistant ovarian cancer cells, (ii) selectively kills ovarian CSC, thereby reducing tumor initiation capacity, and (iii) in multiple tumor models combined with chemotherapy is able to cure ~50% of animals with chemoresistant ovarian cancer. Unfortunately, 673A and other analogs are poor candidates for clinical development as they are rapidly metabolized and/or are covalent ALDH modifiers. We have recently identified a novel series of potent non-covalent, non-substrate ALDH1A inhibitors. Importantly, our preliminary data demonstrate that these new ALDHi kill CSC and synergize with chemotherapy. Isoenzyme selectivity of the ALDHi can be readily modified by minor structural changes. The overarching goal of this work will be to determine if isoenzyme-selective inhibition of ALDH1A will constitute a safe and effective adjunct for sensitizing the treatment of recurrent ovarian cancer to existing chemotherapy. We will also identify which ALDH1A isozyme inhibition profile(s) is/are most effective. We propose to: 1) optimize ALDH1A inhibitor based on our novel chemical series for potency and isozyme selectivity, guided by new co-crystal structural information; 2) determine which ALDH1A inhibitors most effectively deplete ovarian CSC in vitro; 3) evaluate optimal inhibitors for pharmacokinetic properties; and 4) select optimal probes for evaluation in murine xenograft models of chemoresistant ovarian cancer. Our proposal is innovative in its use of a new ALDH1A : inhibitor co-crystal structure and homology models for structure-based design of isozyme- selective inhibitors, and the ultimate use of patient-derived xenografts with human stroma to more accurately predict efficacy in the clinic. This work will be significant in determining whether ALDH1A family inhibition can overcome ovarian cancer chemoresistance in vivo and which isozyme inhibition profile is optimal. Finally, our work will progress toward the development of an effective adjunct treatment for recurrent ovarian cancer, a dire unmet medical need, thus there is high potential for significant impact.