Miyazaki Yukiko, Inaoka Daniel K, Shiba Tomoo, Saimoto Hiroyuki, Sakura Takaya, Amalia Eri, Kido Yasutoshi, Sakai Chika, Nakamura Mari, Moore Anthony L, Harada Shigeharu, Kita Kiyoshi
School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan.
Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
Front Pharmacol. 2018 Sep 4;9:997. doi: 10.3389/fphar.2018.00997. eCollection 2018.
Human dihydroorotate dehydrogenase (HsDHODH) is a key enzyme of pyrimidine biosynthesis pathway. It is located on the mitochondrial inner membrane and contributes to the respiratory chain by shuttling electrons to the ubiquinone pool. We have discovered ascofuranone (), a natural compound produced by , and its derivatives are a potent class of HsDHODH inhibitors. We conducted a structure-activity relationship study and have identified functional groups of that are essential for the inhibition of HsDHODH enzymatic activity. Furthermore, the binding mode of and its derivatives to HsDHODH was demonstrated by co-crystallographic analysis and we show that these inhibitors bind at the ubiquinone binding site. In addition, the cytotoxicities of and its potent derivatives , , and were studied using human cultured cancer cells. Interestingly, they showed selective and strong cytotoxicity to cancer cells cultured under microenvironment (hypoxia and nutrient-deprived) conditions. The selectivity ratio of under this microenvironment show the most potent inhibition which was over 1000-fold higher compared to that under normal culture condition. Our studies suggest that under microenvironment conditions, cancer cells heavily depend on the pyrimidine biosynthesis pathway. We also provide the first evidence that and its derivatives are potential lead candidates for drug development which target the HsDHODH of cancer cells living under a tumor microenvironment.
人类二氢乳清酸脱氢酶（HsDHODH）是嘧啶生物合成途径中的关键酶。它位于线粒体内膜上，通过将电子穿梭至泛醌池而对呼吸链起作用。我们发现了由……产生的天然化合物阿斯科呋喃酮（），其衍生物是一类有效的HsDHODH抑制剂。我们进行了构效关系研究，并确定了……中对抑制HsDHODH酶活性至关重要的官能团。此外，通过共结晶分析证明了……及其衍生物与HsDHODH的结合模式，并且我们表明这些抑制剂结合在泛醌结合位点。另外，使用人培养癌细胞研究了……及其有效衍生物……、……和……的细胞毒性。有趣的是，它们对在微环境（缺氧和营养缺乏）条件下培养的癌细胞表现出选择性且强烈的细胞毒性。在这种微环境下……的选择性比率显示出最强的抑制作用，与正常培养条件下相比高出1000倍以上。我们的研究表明，在微环境条件下，癌细胞严重依赖嘧啶生物合成途径。我们还提供了首个证据，证明……及其衍生物是针对生活在肿瘤微环境中的癌细胞的HsDHODH进行药物开发的潜在先导候选物。
