ACS Chem Biol. 2018 Aug 17;13(8):1970-1977. doi: 10.1021/acschembio.8b00381. Epub 2018 Jul 23.
Chemical genetics is a powerful approach for identifying therapeutically active small molecules, but identifying the mechanisms of action underlying hit compounds remains challenging. Chemoproteomic platforms have arisen to tackle this challenge and enable rapid mechanistic deconvolution of small-molecule screening hits. Here, we have screened a cysteine-reactive covalent ligand library to identify hit compounds that impair cell survival and proliferation in nonsmall cell lung carcinoma cells, but not in primary human bronchial epithelial cells. Through this screen, we identified a covalent ligand hit, DKM 3-42, which impaired both in situ and in vivo lung cancer pathogenicity. We used activity-based protein profiling to discover that the primary target of DKM 3-42 was the catalytic cysteine in aldehyde dehydrogenase 3A1 (ALDH3A1). We performed further chemoproteomics-enabled covalent ligand screening directly against ALDH3A1, and identified a more potent and selective lead covalent ligand, EN40, which inhibits ALDH3A1 activity and impairs lung cancer pathogenicity. We show here that ALDH3A1 represents a potentially novel therapeutic target for lung cancers that express ALDH3A1 and put forth two selective ALDH3A1 inhibitors. Overall, we show the utility of combining chemical genetics screening of covalent ligand libraries with chemoproteomic approaches to rapidly identify anticancer leads and targets.
化学遗传学是一种强大的方法，可用于鉴定具有治疗活性的小分子，但鉴定潜在命中化合物的作用机制仍然具有挑战性。化学蛋白质组学平台的出现解决了这一挑战，并能够快速对小分子筛选命中化合物进行机制剖析。在这里，我们筛选了一个半胱氨酸反应性共价配体文库，以鉴定在非小细胞肺癌细胞中但不在原代人支气管上皮细胞中抑制细胞存活和增殖的命中化合物。通过该筛选，我们鉴定出一种共价配体命中化合物 DKM 3-42，它可损害原位和体内肺癌的致病性。我们使用基于活性的蛋白质谱分析发现，DKM 3-42 的主要靶标是醛脱氢酶 3A1（ALDH3A1）中的催化半胱氨酸。我们进一步针对 ALDH3A1 进行了化学蛋白质组学支持的共价配体筛选，并鉴定出一种更有效和选择性的先导共价配体 EN40，它可抑制 ALDH3A1 活性并损害肺癌的致病性。我们在这里表明，ALDH3A1 代表了表达 ALDH3A1 的肺癌的潜在新型治疗靶标，并提出了两种选择性 ALDH3A1 抑制剂。总体而言，我们展示了将共价配体文库的化学遗传学筛选与化学蛋白质组学方法相结合以快速鉴定抗癌先导化合物和靶标的实用性。
