京大戟中稀有二萜类成分的抗肿瘤活性及构效关系研究

Euphorbia Pekinensis Radix has effects of expelling water retention with drastic purgative and reducing swelling, which is usually used for liver cirrhosis and liver cancer in clinical, but its material basis of antitumor activity has not been elucidated. A series of rare Casbane diterpenes (CTC) have been isolated from Euphorbia Pekinensis Radix in our previous study, which exhibited significant antitumor activity in vitro and in vivo. Besides, the apoptosis of tumor cells induced by CTC was found to be closely related to the regulation of PI3K/Akt signaling pathway, however, its mechanism and structure-activity relationship is still not clear. Based on these, the following tasks would been planned to carry out: (1) Lock the active fraction containing CTC and obtain such ingredients by a variety of chromatographic techniques, (2) Explore the influence of CTC’s structure on the expression of protein in PI3K/Akt signaling pathway, which would explain the structure-activity relationship and possible mechanism of the apoptosis of tumor cell, (3) Investigative the correlation of CTC’s structure and expression of the key protein in PI3K/Akt signaling pathway with the help of computer-aided designing. Finally, elucidating the structure-activity relationship of CTC by the biological evaluation and computer simulation that would provide basis for the leading compounds and discovery of antitumor drug.

京大戟具有峻下逐水、消肿散结之功，多见于肝癌及肝硬化腹水的治疗，但其抗肿瘤作用的物质基础尚未阐明。本课题组前期已从京大戟中分离得到系列稀有Casbane型二萜成分（CTC），体内外实验均证实该类成分抗肿瘤作用确切，可能为其发挥抗肿瘤作用的物质基础。并发现CTC诱导肿瘤细胞凋亡与调控PI3K/Akt信号通路密切相关，而其构效关系和作用机制尚不清晰。基于此，本项目拟开展以下工作：(1)快速锁定含有CTC的活性组分群，采用多种色谱技术获得结构多样的此类成分；（2）探究CTC多样性结构对PI3K/Akt信号通路中蛋白表达的差异影响，阐释其构效关系及诱导肿瘤细胞凋亡的可能机制；（3）借助计算机辅助设计挖掘CTC结构与PI3K/Akt信号通路中蛋白表达之间的相关性。从生物活性评价与计算机模拟角度阐明CTC抗肿瘤的构效关系，为抗肿瘤先导物及新药发现提供依据。

本课题是在京大戟治疗癥瘕积聚、恶疮毒瘤的中医理论指导下，基于京大戟抗肿瘤活性确切，探究京大戟二萜成分的抗肿瘤机制及其构效关系。本课题主要研究发现有：.（1）对京大戟化学成分进行了系统分离，共分离得到了49个化合物，鉴定其中的41个化合物，其中包括7个新的稀有Casbane型二萜以及1个新的海松烷型二萜。.（2）基于细胞活性筛选，评价不同结构类型二萜成分的抗肿瘤活性以及代表性二萜对肝癌细胞增殖、周期及凋亡作用。.（3）基于小鼠体内移植肿瘤模型与自发性肿瘤动物模型，我们首次阐明了Casbane型二萜的抗肿瘤机制，研究发现Casbane型二萜可通过内质网应激、PI3K/AKT/mTOR信号通路介导细胞凋亡抑制肝癌细胞的生长。.（4）借助计算机辅助设计模拟结构多样性的Casbane型二萜与PI3K基因结合的强弱，结果表明其5、11位侧链为其活性基团，它可能是决定与大分子作用方式的关键基团，对该类化合物与大分子的相互作用起到决定性的作用，这与前期活性评价结果一致。.以上研究发现为阐释中药京大戟治疗癥瘕积聚、恶疮毒瘤的化学物质基础，为大戟属植物资源开发利用提供依据；从生物活性评价与计算机模拟角度阐明Casbane型二萜成分抗肿瘤的构效关系，为进一步结构修饰以及创制新药或新药先导物提供重要依据。