Inhibition of the mitochondrial pyrimidine biosynthesis enzyme dihydroorotate dehydrogenase by doxorubicin and brequinar sensitizes cancer cells to TRAIL-induced apoptosis
Inhibition of the mitochondrial pyrimidine biosynthesis enzyme dihydroorotate dehydrogenase by doxorubicin and brequinar sensitizes cancer cells to TRAIL-induced apoptosis
复制标题
DOI：
10.1038/onc.2013.313
复制
发表时间：
2014-07-03
期刊：
影响因子：
8
通讯作者：
Perala, M.
中科院分区：
文献类型：
--
作者：
He, T.;Haapa-Paananen, S.;Perala, M.
肿瘤坏死因子相关的凋亡诱导配体(TRAIL)是一种很有前途的选择性杀伤肿瘤细胞的药物。然而，TRAIL单一疗法并不成功，因为许多癌细胞对TRAIL具有耐药性。化疗药物，如阿霉素，已被证明与TRAIL具有协同作用，但确切的作用机制尚不清楚。在这项研究中，我们对阿霉素处理的U1690细胞进行了高通量小干扰RNA筛选和全基因组基因表达谱分析，以探索阿霉素-TRAIL协同作用的新机制。综合筛选和表达谱结果，二氢罗酸脱氢酶(DHODH)被确定为一个潜在的候选基因。DHODH是嘧啶合成途径中的限速酶，其表达被阿霉素下调。我们发现，在2D和3D培养中，沉默DHODH或抑制DHODH活性显著增加U1690细胞对TRAIL诱导的细胞凋亡的敏感性，并伴随着c-FLIPL的下调以及线粒体的去极化。此外，嘧啶合成途径的终产物尿苷能够挽救长春新碱和阿霉素的致敏作用。此外，其他几种癌细胞株LNCaP、MCF-7和HT-29也显示出对TRAIL的敏感度。综上所述，我们的研究结果确定了一个新的蛋白质靶点及其抑制剂brequina，作为基于TRAIL的联合癌症治疗的潜在药物，并首次强调了线粒体DHODH酶和嘧啶途径在介导TRAIL敏感性的癌细胞中的重要性。
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising agent in selectively killing tumor cells. However, TRAIL monotherapy has not been successful as many cancer cells are resistant to TRAIL. Chemotherapeutic agents, such as doxorubicin have been shown to act synergistically with TRAIL, but the exact mechanisms of actions are poorly understood. In this study, we performed high-throughput small interfering RNA screening and genome-wide gene expression profiling on doxorubicin-treated U1690 cells to explore novel mechanisms underlying doxorubicin-TRAIL synergy. The screening and expression profiling results were integrated and dihydroorotate dehydrogenase (DHODH) was identified as a potential candidate. DHODH is the rate-limiting enzyme in the pyrimidine synthesis pathway, and its expression was downregulated by doxorubicin. We demonstrated that silencing of DHODH or inhibition of DHODH activity by brequinar dramatically increased the sensitivity of U1690 cells to TRAIL-induced apoptosis both in 2D and 3D cultures, and was accompanied by downregulation of c-FLIPL as well as by mitochondrial depolarization. In addition, uridine, an end product of the pyrimidine synthesis pathway was able to rescue the sensitization effects initiated by both brequinar and doxorubicin. Furthermore, several other cancer cell lines, LNCaP, MCF-7 and HT-29 were also shown to be sensitized to TRAIL by brequinar. Taken together, our findings have identified a novel protein target and its inhibitor, brequinar, as a potential agent in TRAIL-based combinatorial cancer therapy and highlighted for the first time the importance of mitochondrial DHODH enzyme and pyrimidine pathway in mediating TRAIL sensitization in cancer cells.