单端孢霉烯大环内酯抗肿瘤机制及构效关系研究

Biotoxin is an important resource for developing new anti-cancer drug. As one kind of mycotoxin, trichothecene macrolide was a valuable leading compound for developing new drug because of its varied structure type (the 10,13-cyclotrichothecane derivative could be found only in symbiotic strain up to now) and remarkable anti-cancer activity. In previous experiment, 18 of trichothecene macrolides had been obtained from endophyte M. roridum and most of them shown strong cytotoxicity to the test human tumor cell lines in vitro. Cytotoxicity of trichothecene macrolide was depended much on their structure, espeically the 12,13-epoxy group. Preliminary research indicated that trichothecene macrolides mytoxin B (bearing a 12,13-epoxy) and myrothecine A (10,13-cyclotrichothecane derivative of mytoxin B) were strong cytotoxic to the human hepatocarcinoma cell line SMMC-7721 and they could induce apoptosis and/or autophagy of SMMC-7721 cell line, which might be regulated by PI3K/PKB signal pathway. Based on above-mentioned researches, further research on molecular mechanism of induced-apoptosis and induced-autophagy in SMMC-7721 cell line by trichothecene macrolides and their structure-activity relationship will be carried out in this project. The target molecule of the trichothecene macrolide would be discovered and research results would provide important information for molecular design and structure modification in new drug development in the future.

生物毒素是抗肿瘤新药的重要来源。作为一种真菌毒素，单端孢霉烯大环内酯具有丰富的结构类型（10,13-碳环衍生物目前仅在共生菌中发现）和显著的抗肿瘤活性，是极有价值的新药先导化合物。前期实验从植物内生菌M. roridum中分离得到18个单端孢霉烯大环内酯化合物，它们大多对测试肿瘤细胞株具有较强的体外抗肿瘤活性；活性与结构密切相关，尤其是12,13-环氧环对活性影响显著。实验还发现，单端孢霉烯大环内酯mytoxin B（含12,13-环氧环）和myrothecine A（mytoxin B的10,13-碳环衍生物）对人肝癌细胞株SMMC-7721的较强体外抗肿瘤活性与诱导肿瘤细胞凋亡和/或自噬相关，且与PI3K/PKB信号途径有关。因此，本项目拟深入研究单端孢霉烯大环内酯诱导SMMC-7721细胞凋亡和/或自噬的分子机制及构效关系，以明确抗肿瘤作用的靶分子，为新药分子设计及化学结构修饰与改造提供重要依据。

生物毒素是抗肿瘤新药的重要来源，作为一种真菌毒素，单端孢霉烯大环内酯具有丰富的结构类型和显著的抗肿瘤活性，是极有价值的新药先导化合物。早期研究表明，单端孢霉烯及其大环内酯通过抑制肿瘤细胞蛋白质合成而发挥强抗肿瘤作用，而这正是它们产生毒性的主要原因。因此，研究单端孢霉烯大环内酯的抗肿瘤构效关系及作用机制，发现关键药效团，通过化学结构修饰与改造以提高其活性和靶向性、降低毒性，成为研制单端孢霉烯大环内酯类抗肿瘤新药的关键。.本项目采用比较分子场法CoMFA和比较分子相似性法CoMSIA研究单端孢霉烯大环内酯的三维定量构效关系，考虑静电场和立体场、疏水性、氢键供体和氢键受体对生物活性的影响。结果显示，所有CoMFA和CoMSIA模型都具有较好的预测性，上述因素对化合物活性影响的理论预测与实验值非常一致，可为化合物的结构优化提供指导。.本项目对单端孢霉烯大环内酯mytoxin B（含10,13-环氧环）和myrothecine A（mytoxin B 的10,13-碳环衍生物）的体外抗肿瘤活性进行研究，结果发现，mytoxin B的活性明显强于myrothecine A，12,13-环氧环对活性影响显著；它们对人肝癌细胞株SMMC-7721的增殖抑制活性皆表现出一定的量效和时效关系；它们都能诱导SMMC-7721细胞S期周期阻滞，myrothecine A主要通过增加p27蛋白的表达而抑制细胞增殖，而mytoxin B对SMMC-7721细胞的增殖抑制作用除与上调p27蛋白表达有关外，可能还有其他相关作用机制；它们都能诱导SMMC-7721细胞凋亡，该诱导凋亡作用涉及死亡受体途径和线粒体途径，且与PI3K/Akt信号途径和MAPK信号途径有关；低浓度时mytoxin B能显著增强SMMC-7721细胞的自噬活性。mytoxin B和myrothecine A 对SMMC-7721细胞的体外抗肿瘤机制值得进一步研究。