Conformation and energy investigation of microtubule longitudinal dynamic instability induced by natural products

The natural products plinabulin, docetaxel, and vinblastine are microtubule targeting agents (MTAs). They have been used alone or in combination in cancer treatment. However, the exact nature of their effects on microtubule (MT) polymerization dynamics is poorly understood. To elucidate the longitudinal conformational and energetic changes during MT dynamics, a total of 140 ns molecular dynamic simulations combined with binding free energy calculations were performed on seven tubulin models. The results indicated that the drugs disrupted MT polymerization by altering both MT conformation and binding free energy of the neighboring tubulin subunits. The combination of plinabulin and docetaxel destabilized MT polymerization due to bending MT and weakening the polarity of tubulin polymerization. The new combination of docetaxel and vinblastine synergistically enhanced MT depolymerization and bending, while plinabulin and vinblastine had no synergistic inhibitory effects. The results were verified by the tubulin assembly assay. Our study obtained a comprehensive understanding of the action mechanisms of three natural drugs and their combinations on MT dynamic, provided theoretical guidance for new MTA combinations, and would promote the optimal use of MTA and contribute to developing new MTAs as anticancer agents.     

海洋抗肿瘤候选药物普那布林(Plinabulin)及类似物的研究进展孙天文1,2,丁忠鹏1, 王世潇2, 赵建春1,2, 管华诗1,2,

【】 微管蛋白是细胞骨架的重要组成部分,在维持形态、信号传导及有丝分裂等过程中起着重要的作用。普那布林(Plinabulin)是在从海洋焦曲霉菌中分离得到的天然产物 Phenylahistin 结构基础上,经构效关系研究,合成出的二酮哌嗪类微管蛋白抑制剂。普那布林作为抗肿瘤候选药物,目前已进入临床二期研究。近年来,为了获得高效、低毒和生物利用度更高的普那布林衍生物,本领域研究人员进行了大量的优化研究,获得了一些具有更好活性的衍生物。本文就普那布林及其类似物优化的研究进展进行综述。     

Vascular effects of plinabulin (NPI-2358) and the influence on tumour response when given alone or combined with radiation

Abstract

Purpose: This study investigated the anti-tumour effects of the novel vascular disrupting agent plinabulin (NPI-2358) when given alone or combined with radiation.

Materials and methods: Foot implanted C3H mammary carcinomas or leg implanted KHT sarcomas were used, with plinabulin injected intraperitoneally. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) measurements were made with gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) on a 7-tesla magnet. Treatment response was assessed using regrowth delay (C3H tumours), clonogenic survival (KHT sarcomas) or histological estimates of necrosis for both models.

Results: Plinabulin (7.5 mg/kg) significantly reduced the initial area under curve (IAUC) and the transfer constant (K^trans) within 1 hour after injection, reaching a nadir at 3 h, but returning to normal within 24 h. A dose-dependent decrease in IAUC and K^trans, was seen at 3 h. No significant anti-tumour effects were observed in the C3H tumours until doses of 12.5 mg/kg were achieved, but started at 1.5 mg/kg in the KHT sarcoma. Irradiating tumours 1 h after injecting plinabulin enhanced response in both models.

Conclusions: Plinabulin induced a time- and dose-dependent decrease in tumour perfusion. The KHT sarcoma was more sensitive than the C3H tumour to the anti-tumour effects of plinabulin, while radiation response was enhanced in both models.