Han Yan, Wu Yungang, Xu Yi, Guo Wentao, Zhang Na, Wang Xiaoyi
Department of TCM Orthopedics & Traumatology, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China.
Department of Pharmacy, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China.
PeerJ. 2019 Jan 21;7:e6299. doi: 10.7717/peerj.6299. eCollection 2019.
Monopolar spindle 1 (Mps1/TTK) is an apical dual-specificity protein kinase in the spindle assembly checkpoint (SAC) that guarantees accurate segregation of chromosomes during mitosis. High levels of Mps1 are found in various types of human malignancies, such as glioblastoma, osteosarcoma, hepatocellular carcinoma, and breast cancer. Several potent inhibitors of Mps1 exist, and exhibit promising activity in many cell cultures and xenograft models. However, resistance due to point mutations in the kinase domain of Mps1 limits the therapeutic effects of these inhibitors. Understanding the detailed resistance mechanism induced by Mps1 point mutations is therefore vital for the development of novel inhibitors against malignancies.
In this study, conventional molecular dynamics (MD) simulation and Gaussian accelerated MD (GaMD) simulation were performed to elucidate the resistance mechanisms of Cpd-5, a potent Mps1 inhibitor, induced by the four representative mutations I531M, I598F, C604Y, S611R.
Our results from conventional MD simulation combined with structural analysis and free energy calculation indicated that the four mutations weaken the binding affinity of Cpd-5 and the major variations in structural were the conformational changes of the P-loop, A-loop and αC-helix. Energetic differences of per-residue between the WT system and the mutant systems indicated the mutations may allosterically regulate the conformational ensemble and the major variations were residues of Ile-663 and Gln-683, which located in the key loops of catalytic loop and A-loop, respectively. The large conformational and energetic differences were further supported by the GaMD simulations. Overall, these obtained molecular mechanisms will aid rational design of novel Mps1 inhibitors to combat inhibitor resistance.
单极纺锤体1（Mps1/TTK）是纺锤体组装检查点（SAC）中的一种顶端双特异性蛋白激酶，可确保有丝分裂期间染色体的准确分离。在各种类型的人类恶性肿瘤中，如胶质母细胞瘤、骨肉瘤、肝细胞癌和乳腺癌，均发现高水平的Mps1。存在几种有效的Mps1抑制剂，并且在许多细胞培养物和异种移植模型中表现出有前景的活性。然而，由于Mps1激酶结构域中的点突变导致的耐药性限制了这些抑制剂的治疗效果。因此，了解由Mps1点突变诱导的详细耐药机制对于开发针对恶性肿瘤的新型抑制剂至关重要。
在本研究中，进行了传统分子动力学（MD）模拟和高斯加速MD（GaMD）模拟，以阐明由四种代表性突变I531M、I598F、C604Y、S611R诱导的强效Mps1抑制剂Cpd-5的耐药机制。
我们结合结构分析和自由能计算的传统MD模拟结果表明，这四种突变削弱了Cpd-5的结合亲和力，结构上的主要变化是P环、A环和αC螺旋的构象变化。野生型系统和突变体系统之间每个残基的能量差异表明，这些突变可能通过变构调节构象集合，主要变化是分别位于催化环和A环关键环中的Ile-663和Gln-683残基。GaMD模拟进一步支持了大的构象和能量差异。总体而言，这些获得的分子机制将有助于合理设计新型Mps1抑制剂以对抗抑制剂耐药性。
