Roaten J B, Kazanietz M G, Sweatman T W, Lothstein L, Israel M, Parrill A L
Department of Pharmacology, University of Tennessee College of Medicine, Memphis, Tennessee 38163, USA.
J Med Chem. 2001 Mar 29;44(7):1028-34. doi: 10.1021/jm000289v.
N-Benzyladriamycin-14-valerate (AD 198) is a semisynthetic anthracycline with experimental antitumor activity superior to that of doxorubicin (DOX). AD 198, unlike DOX, only weakly binds DNA, is a poor inhibitor of topoisomerase II, and circumvents anthracycline-resistance mechanisms, suggesting a unique mechanism of action for this novel analogue. The phorbol ester receptors, protein kinase C (PKC) and beta2-chimaerin, were recently identified as selective targets for AD 198 in vitro. In vitro, AD 198 competes with [3H]PDBu for binding to a peptide containing the isolated C1b domain of PKC-delta (deltaC1b domain). In the present study molecular modeling is used to investigate the interaction of AD 198 with the deltaC1b domain. Three models are identified wherein AD 198 binds into the groove formed between amino acid residues 6-13 and 21-27 of the deltaC1b domain in a manner similar to that reported for phorbol-13-acetate and other ligands of the C1 domain. Two of the identified models are consistent with previous experimental data demonstrating the importance of the 14-valerate side chain of AD 198 in binding to the C1 domain as well as current data demonstrating that translocation of PKC-alpha to the membrane requires the 14-valerate substituent. In this regard, the carbonyl of the 14-valerate participates in hydrogen bonding to the deltaC1b while the acyl chain is positioned for stabilization of the membrane-bound protein-ligand complex in a manner analogous to the acyl chains of the phorbol esters. These studies provide a structural basis for the interaction of AD 198 with the deltaC1b domain and a starting point for the rational design of potential new drugs targeting PKC and other proteins with C1 domains.
N-苄基阿霉素-14-戊酸酯（AD 198）是一种半合成蒽环类药物，其实验性抗肿瘤活性优于阿霉素（DOX）。与DOX不同，AD 198仅与DNA弱结合，是拓扑异构酶II的弱抑制剂，并且能规避蒽环类耐药机制，这表明这种新型类似物具有独特的作用机制。佛波酯受体、蛋白激酶C（PKC）和β2-嵌合蛋白最近被确定为AD 198在体外的选择性靶点。在体外，AD 198与[3H]佛波醇-12,13-二丁酸酯（PDBu）竞争结合含有PKC-δ分离C1b结构域（δC1b结构域）的肽。在本研究中，分子建模用于研究AD 198与δC1b结构域的相互作用。确定了三种模型，其中AD 198以类似于佛波醇-13-乙酸酯和C1结构域其他配体的方式结合到δC1b结构域氨基酸残基6-13和21-27之间形成的凹槽中。所确定的两种模型与先前的实验数据一致，这些数据证明了AD 198的14-戊酸侧链在与C1结构域结合中的重要性，以及当前的数据表明PKC-α向膜的转位需要14-戊酸取代基。在这方面，14-戊酸的羰基参与与δC1b的氢键形成，而酰基链的定位方式类似于佛波酯的酰基链，用于稳定膜结合的蛋白质-配体复合物。这些研究为AD 198与δC1b结构域的相互作用提供了结构基础，并为合理设计靶向PKC和其他具有C1结构域的蛋白质的潜在新药提供了起点。
