逆转癌症多药耐药天然产物的计算机辅助结构优化及构效关系研究

Multiple drug resistance (MDR) in cancer cells is characterized in vitro by cross-resistance towards many different anticancer agents that have no common chemical structure, pharmacological target, or metabolic pathway. ‘‘Classical MDR’’ is attributed to the overexpression of plasma membrane P-glycoprotein (P-gp) in resistant cells. Its activity results in a marked reduction in the intracellular concentration of a wide range of substrates including anticancer drugs. Efflux of these drugs out of cells by P-gp is a reason for failure of chemotherapy. P-gp-mediated drug efflux and the associated intracellular accumulation deficit can be circumvented by a wide range of compounds, many of which are common pharmaceuticals in clinical use for conditions other than cancer. .To date, third-generation inhibitors of P-pg have been developed but none are approved for use clinically due to their unwanted side effects. Therefore, the search for more potent chemosensitizers with desirable pharmacology is of paramount clinical importance. Agents derived from plant origin are being increasingly utilized in drug discovery and in drug development programs. Identifying natural compounds capable of circumventing MDR with minimal adverse side effects is an attractive goal..As part of our ongoing research of identifying novel chemosensitizers from medicinal plants, a series of damarane-type gypenoside of Gynostemma pentaphyllum, a perennial climbing herb that grows wildly in Southern China has been identified to circumvent Vincristine resistance in KB/VCR cells, and Sorafenib resistance in HepG2/Sora and 7721/Sora cells. The present study demonstrates that one of the gypenoside, H6 prepared from Gynostemma pentaphyllum exhibited potent and specific reversal of VCR resistance in KB/VCR cells, and Sorafenib resistance in HepG2/Sora and 7721/Sora cells. It is likely that H6 as a lead compound could provide a rational approach for the design of selective anticancer treatment regimens for the treatment of cancer clinically.

肿瘤细胞对化疗药物的多药耐药性（MDR）是化疗失败的主要原因，肿瘤的MDR现象产生的途径较多，有其复杂的分子生物学机制，其中研究最多的机制为药物摄入减少或者药物外排增加（主要通过P-gp蛋白介导），目前针对该机制的肿瘤增敏剂已经开发了三代，但临床应用多表现出毒性和副作用。研究发现，天然产物肿瘤增敏剂有可能克服这些毒副反应，前期我们研究发现来源于绞股蓝皂苷元类成分H6（结构见报告正文）具有很好的逆转MDR作用，下一步我们将以H6为先导物，以P-gp蛋白为靶标，利用计算机辅助药物设计的基本原理，设计并制备系列结构衍生物并进行MDR活性评价。同时总结其抗MDR构效关系，指导并期望寻找活性更好、毒性更低和具有优良ADME性质的逆转MDR药物侯选物，为研制创新药物奠定坚实的基础。我们希望通过计算机辅助药物设计进行基于中药中活性成分的新药开发研究这一案例，为中药的现代化开发提供新的研究思路。

多药耐药（multidrug resistance, MDR）是肿瘤化疗的最大障碍，逆转耐药是提高化疗疗效的首要问题。肿瘤MDR机制多样且复杂，其中P-gp过表达是最典型的多药耐药机制。本项目以天然产物达玛烷三萜皂苷（绞股蓝皂苷元H6及原人参二醇PDD为代表）以及查耳酮DMC为先导化合物，以P-gp糖蛋白为靶标，采用生物电子等排和计算机辅助药物设计的分子对接等策略设计了一系列天然产物的衍生物。随后初步通过MTT实验（KB/VCR和MCF-7/DOX细胞）对衍生物进行了体外抗癌增敏活性评价，总结了构效关系，并发现13、19和D18在逆转MDR方面表现出较高的活性。对增敏活性最好的D18进一步机制研究发现，D18几乎无细胞毒性和对P-gp具有高度选择性抑制作用，并且细胞蓄积实验、Western blotting以及实时荧光定量PCR（RT-PCR）分别表明D18具有抑制P-gp转运功能、在蛋白质和mRNA水平上具有抑制P-gp表达的作用。上述实验表明D18可以逆转P-gp介导的肿瘤多药耐药并且具有良好开发前景。.本项目共设计制备基于天然产物的化合物157个，发表SCI论文10篇，中文核心论文1篇，申报国家专利1项并授权，培养博士研究生1名，硕士研究生2名，完成了本项目的各项预期研究结果。上述工作阐明天然产物在肿瘤多药耐药领域具有良好开发前景，对今后研究和开发高效、低毒的MDR逆转剂具有重要意义，同时对于基于天然产物的计算机辅助药物设计提供了可供借鉴的研究思路。