Patil Sachin P, Pacitti Michael F, Gilroy Kevin S, Ruggiero John C, Griffin Jonathan D, Butera Joseph J, Notarfrancesco Joseph M, Tran Shawn, Stoddart John W
NanoBio Laboratory, Department of Chemical Engineering, Widener University, Chester, PA, 19013, USA,
J Comput Aided Mol Des. 2015 Feb;29(2):155-63. doi: 10.1007/s10822-014-9811-6. Epub 2014 Nov 7.
The inhibition of tumor suppressor p53 protein due to its direct interaction with oncogenic murine double minute 2 (MDM2) protein, plays a central role in almost 50 % of all human tumor cells. Therefore, pharmacological inhibition of the p53-binding pocket on MDM2, leading to p53 activation, presents an important therapeutic target against these cancers expressing wild-type p53. In this context, the present study utilized an integrated virtual and experimental screening approach to screen a database of approved drugs for potential p53-MDM2 interaction inhibitors. Specifically, using an ensemble rigid-receptor docking approach with four MDM2 protein crystal structures, six drug molecules were identified as possible p53-MDM2 inhibitors. These drug molecules were then subjected to further molecular modeling investigation through flexible-receptor docking followed by Prime/MM-GBSA binding energy analysis. These studies identified fluspirilene, an approved antipsychotic drug, as a top hit with MDM2 binding mode and energy similar to that of a native MDM2 crystal ligand. The molecular dynamics simulations suggested stable binding of fluspirilene to the p53-binding pocket on MDM2 protein. The experimental testing of fluspirilene showed significant growth inhibition of human colon tumor cells in a p53-dependent manner. Fluspirilene also inhibited growth of several other human tumor cell lines in the NCI60 cell line panel. Taken together, these computational and experimental data suggest a potentially novel role of fluspirilene in inhibiting the p53-MDM2 interaction. It is noteworthy here that fluspirilene has a long history of safe human use, thus presenting immediate clinical potential as a cancer therapeutic. Furthermore, fluspirilene could also serve as a structurally-novel lead molecule for the development of more potent, small-molecule p53-MDM2 inhibitors against several types of cancer. Importantly, the combined computational and experimental screening protocol presented in this study may also prove useful for screening other commercially-available compound databases for identification of novel, small molecule p53-MDM2 inhibitors.
肿瘤抑制蛋白p53因与致癌性鼠双微体2（MDM2）蛋白直接相互作用而受到抑制，这在几乎50%的人类肿瘤细胞中起着核心作用。因此，对MDM2上p53结合口袋进行药理抑制从而导致p53激活，是针对这些表达野生型p53的癌症的一个重要治疗靶点。在此背景下，本研究采用综合虚拟和实验筛选方法，筛选已批准药物数据库以寻找潜在的p53-MDM2相互作用抑制剂。具体而言，使用一种结合四个MDM2蛋白晶体结构的整体刚性受体对接方法，确定了六个药物分子为可能的p53-MDM2抑制剂。然后通过柔性受体对接，接着进行Prime/MM-GBSA结合能分析，对这些药物分子进行进一步的分子模拟研究。这些研究确定氟司必林（一种已批准的抗精神病药物）是最佳候选物，其与MDM2的结合模式和能量与天然MDM2晶体配体相似。分子动力学模拟表明氟司必林与MDM2蛋白上的p53结合口袋稳定结合。氟司必林的实验测试显示，其以p53依赖的方式显著抑制人结肠肿瘤细胞的生长。氟司必林还抑制了NCI60细胞系面板中的其他几种人类肿瘤细胞系的生长。综上所述，这些计算和实验数据表明氟司必林在抑制p53-MDM2相互作用方面可能具有新的作用。值得注意的是，氟司必林在人类中有长期安全使用的历史，因此作为癌症治疗药物具有直接的临床潜力。此外，氟司必林还可作为一种结构新颖的先导分子，用于开发针对多种癌症类型的更有效小分子p53-MDM2抑制剂。重要的是，本研究中提出的计算和实验相结合的筛选方案，可能也有助于筛选其他商业可用的化合物数据库，以鉴定新型小分子p53-MDM2抑制剂。
