PARP-1与PI3K双靶点抑制剂的设计、合成及构效关系研究

PARP-1 inhibitors are an effective treatment for BRCA1/2-defection triple-negative breast and ovarian cancer. Although they have fewer side effects, the limited indications and drug resistance of PARP-1 inhibitors have become the major handicap for their usage. Many researches indicate that PI3K inhibitors could remarkably reduce the drug resistance of PARP-1 and enhance therapeutic effects at the same time. In our previous work, Olaparib (PARP-1 inhibitor) and BKM120 (PI3K inhibitor) were chosen as the lead compounds and PP-1-3 was discovered as PARP-1 (IC50=0.78nM)/PI3Kα (IC50=94nM) dual inhibitor through combination phamarcophores and computer aided drug design method. Based on this result, PP-1-3 was chosen as the lead compound and optimized in this project. Meanwhile, from the designing concept of PP-1-3, another series of compounds were designed and synthesized by combination of the appropriate pharmacophores of Veliparib and BKM120. All target compounds were evaluated their inhibition effect of PARP-1 and PI3K and antitumor activities in vitro and in vivo. The structure-activity relationship of the compounds was analyzed for further research. Our goal is discovering 1-2 novel antitumor drug candidates with high efficiency and providing theoretical basis for the research of multi-acting PARP-1 and PI3K inhibitors as the treatment of cancer.

PARP-1抑制剂对BRCA1/2缺失的女性乳腺癌和卵巢癌的疗效显著，但存在适应症窄和耐药性问题。PI3K抑制剂能有效克服PARP-1抑制剂的耐药性，具有协同增效作用。课题组前期以PARP-1抑制剂Olaparib和PI3K抑制剂BKM120为先导化合物，采用“组合药效团”策略和计算机辅助药物设计方法，首次发现了具有PARP-1（IC50=0.78nM）和PI3K（IC50=94nM）双重抑制活性的化合物PP-1-3。本项目首先对先导物PP-1-3进行结构优化，同时借助PP-1-3的设计理念，将PARP-1抑制剂Veliparib和BKM120的药效团进行组合并衍生化，设计合成两个系列化合物，通过PARP-1、PI3K、体内外抗肿瘤活性筛选，期望获得1~2个活性好、适应症广、不易产生耐药的新型抗肿瘤候选化合物，并进行构效关系分析，为PARP-1和PI3K双靶点抑制剂的深入研究提供理论依据。

为了解决PARP-1抑制剂适应症窄和易产生耐药性的问题，本课题在分析PARP-1和PI3K抑制剂构效关系的基础上，采用“拼合”的策略，将PARP-1抑制剂Olaparib和Veliparib与PI3K抑制剂BKM120结构中相应的药效团进行拼合，借助计算机辅助药物设计方法，发现了对PARP-1 (IC50 = 0.78 nM)和PI3Kα (IC50 = 94 nM)同时具有较好抑制活性的先导化合物IA-3 (PP-1-3)。通过生物电子等排和骨架跃迁等原理对IA-3进行结构修饰以平衡对两个靶点的抑制活性，共设计合成了I~V系列共63个目标化合物,.初步的药理活性评价结果显示，大部分化合物对PARP-1和PI3Kα都具有较高的抑制活性。其中化合物III-1、III-6、IV-1和V-3对PARP-1和PI3Kα两个靶点的抑制活性最优，并对肿瘤细胞HCT116、HCC1937、MDA-MB-231和MDA-MB-468也表现出了较强的增殖抑制活性。初步的药代动力学试验结果显示，水溶性提高后化合物的药代参数也得到了改善，口服生物利用度由III-1的0.25%提高至V-3的22%。体内药效实验结果显示，在50 mg/kg剂量下，化合物III-1、III-6、IV-1和V-3在MDA-MB-468裸鼠移植瘤模型上能够显著抑制肿瘤的生长，抑瘤效果优于阳性药Olaparib (50 mg/kg)和BKM120 (27.5 mg/kg)；其中化合物III-I和III-6的抑瘤作用明显优于Olaparib (50 mg/kg)和BKM120 (27.5 mg/kg) 联用组。初步作用机制研究表明，化合物是通过抑制PI3K信号通路，间接地激活ERK，进而抑制BRCA1/2的表达，导致同源重组功能缺陷，使DNA损伤无法得到修复，最终诱导细胞发生凋亡。在此基础上进行了初步的构效关系分析，为PARP-1和PI3K双靶点抑制剂的深入研究提供了理论依据。