新型双靶点BRD4/PLK1抑制剂的设计、合成及其抗肿瘤作用机制研究

Protein kinase inhibitors and epigenetic regulatory molecules are two main kinds of anticancer drugs developed in recent years. Both kinds of drugs harbor their own advantages and disadvantages in the treatment of cancer, and the development of small molecules which could target at kinase and epigenetic targets simultaneously can avoid the defects of mono-target drug which only targets at kinase or epigenetic protein. This study intends to hunt for new dual ( transcription cofactor BRD4 / serine-threonine kinase PLK1) inhibitors and investigates their in vitro and in vivo anti-tumor activities as well as the mechanism of actions. Previously, a hit compound with novel scaffold was discovered via virtual screening by combining pharmacophore and docking methods. Subsequent optimization of this chemotype led to the discovery of several compounds with improved potency against both targets and these compounds also exhibited preferred antiproliferative activity against a panel of cancer cell lines. Based on these preliminary results, we will investigate the interaction details of our dual BRD4/PLK1 inhibitors with BRD4 and PLK1 respectively to guide our further optimization of this chemotype. Subsequently the .optimized lead compounds will be inspected in vitro and in vivo for their anti-tumor activities as well as the mechanism of actions from biochemical and molecular biologic level, which could provide us the first experimental evidence for such inhibitors in the application of cancer therapy.

蛋白激酶抑制剂和表观遗传调节分子是近年来抗肿瘤药物研发的两大主要方向，二者在肿瘤治疗方面各具特色，各有优劣，开发能同时作用于激酶和表观遗传靶点的小分子化合物可避免单一靶点存在的缺陷而具有治疗上的优势。本课题拟寻找新型双靶点(转录辅因子BRD4/丝-苏氨酸蛋白激酶PLK1)抑制剂并考察其体内外抗肿瘤活性及作用机制。前期基于构建药效团和分子对接的方法发现了具有新颖结构的苗头化合物，经过初步的化学合成和优化，我们已找到了具有一定活性的双靶点抑制剂，并且发现这些双靶点抑制剂对多种肿瘤细胞显示出较好的增殖抑制活性。基于前期的研究基础，本课题将借助结构生物学方法考察双靶点抑制剂与PLK1和BRD4的作用模式,指导双靶点抑制剂的进一步优化，选择优化得到的先导化合物，深入考察其体内外抗肿瘤活性，并从生物化学、分子生物学层面阐释其在不同肿瘤中的作用机制，为这类抑制剂在抗肿瘤方面的应用提供实验依据。

蛋白激酶抑制剂和表观遗传调节分子是近年来抗肿瘤药物研发的两大主要方向，二者在肿瘤治疗方面各具特色，各有优劣，开发能同时作用于激酶和表观遗传靶点的小分子化合物可避免单一靶点存在的缺陷而具有治疗上的优势。本项目基于前期构建药效团和分子对接的方法发现的苗头化合物，设计并合成了3类新型结构的化合物，包括苯并吗啉酮类衍生物、二氢蝶啶酮类衍生物及4,5-二氢-[1,2,4]三唑并[4,3-f]蝶啶类衍生物。从中发现了对PLK1及BRD4均具有较好亲和力的双靶点抑制剂SKLB-0824，其直接作用靶点经过细胞热漂移分析得到验证。该化合物对多种肿瘤细胞株，包括急性髓性白血病、去势性前列腺癌、乳腺癌等，均展现出了良好的增殖抑制活性。作用机制研究表明，在去势性前列腺癌细胞中，SKLB-0824可通过阻止BRD4与雄激素受体的相互作用而抑制雄激素受体下游信号通路，同时通过抑制PLK1导致细胞有丝分裂紊乱，从而使细胞周期阻滞在G2/M期并诱导细胞凋亡。而在急性髓性白血病细胞中，SKLB-0824可通过下调c-Myc及Bcl-2使细胞周期阻滞在G2/M期并诱导细胞凋亡。体内药效学研究表明，SKLB-0824在60mg/kg剂量下能够明显抑制去势性前列腺癌和急性髓性白血病等肿瘤模型的增长。总之，本研究发现了一类新型结构的双靶点PLK1/BRD4抑制剂，该类结构有望通过进一步开发而成为一类新型抗肿瘤候选药物。