LPAR3选择性拮抗剂的设计、合成及抗口腔鳞状细胞癌的活性研究

Lysophosphatidic acid (LPA) is a small lipid that binds to one or more members of a subfamily of G protein-coupled cell surface receptors (LPAR1-6) to trigger intracellular signalling leading to cell growth, survival and invasion and increase tumor cell movement. Our previous data showed that inhibition of LPA binding to LPAR3 can inhibit the migration and invasion of oral squamous cell carcinoma (OSCC) cells, which suggested that a strategy based on the direct targeting of LPA could lead to the development of new OSCC treatments. For this aim, we are going to use a multi-disciplinary approach using computational chemistry, medicinal chemisty and pharmcology to identify LPAR3 selective antagonists. Based on the structure and sequence analysis, the opposite charged amino acid in the binding site between LPAR3 (Lys) and LPA1/2 (Glu) was observed. This observation provides an opportunity for us to design selective antagonists for LPAR3. In the present proposal, we are going to use homology modeling, active site pressurisation (ASP),virtual screening and molecular docking etc. to identify LPAR3 selctive antagonists from the NCI and Zinc molecule databases. QSAR, molecular dynamic simulation and de novo drug design etc. will be applied to optimize the antagonists' structure, and design new compounds based on the interaction between the ligand and receptor. Newly designed compounds will be synthesized, and tested in vitro and in vivo to evaluate the biological effects on OSCC cells. Hopefully 1-3 antagonists with high activity and selectivity to LPAR3 could be identified as leading compounds for future research and the development of new drugs for the treatment of OSCC.

溶血磷脂酸（LPA）能与其G蛋白偶联受体家族（LPAR1-6）结合，从而增进肿瘤细胞的增殖、存活、转移和侵袭。本团队前期研究表明，拮抗LPA与LPAR3的结合将抑制口腔鳞癌细胞的转移和侵袭，因此LPAR3有望成为治疗口腔鳞癌的新靶点。本研究将结合计算化学、药物化学、药效学等多学科交叉确定LPAR3选择性拮抗剂，并测试其抗口腔鳞癌体内外活性。课题组将借助计算机辅助药物设计和活性位点扩张这一新算法，拓展已知拮抗剂的结合位点，并且针对LPAR3与LPAR1,2的关键氨基酸电性相反这一重要特征，通过同源建模、虚拟筛选、分子对接等手段搜索分子数据库寻找LPAR3选择性拮抗剂；在此基础上通过构效关系研究、分子模拟、全新药物设计等手段进行结构优化；通过有机合成确定具有较高活性和选择性的新型LPAR3拮抗剂，并用于体外和体内抗口腔鳞癌的活性研究，预期得到1-3个候选化合物，为抗口腔鳞癌的新药研发奠定基础。

课题组通过综合应用计算机辅助药物设计、虚拟筛选、分子对接、分子模拟、有机合成、生物活性测试等技术，初步获得3个对LPAR3有拮抗作用的小分子，此结构在以往LPAR3拮抗剂的研究中未见报道，因此这将极大拓展该类药物的化学空间。在此基础上，本课题组设计并合成出一系列新型母核的LPAR3拮抗剂，如三氮唑，哌嗪，含联苯的四氮唑和吡唑，共计55个新化合物。这些化合物结构的共同特征是以不同的杂环为连接基团，在其头部和尾部分别引入电负性强的化学基团，如酯基，硝基，三氟甲基，三氟甲氧等，但是由于头部基团靠近LPAR3的亲水层，而尾部伸向亲脂性的内部，因此头部的电负性要强于尾部。然后通过LPAR3和LPAR1的初筛，抑制心肌成纤维细胞增殖的实验，课题组发现了一个活性最好的化合物，其对LPAR1的IC50为0.1uM，与阳性对照药类似。该类拮抗剂表现出很强的体外活性，将可作为先导化合物进行深入研究，从而为抗心肌纤维化的新药研发提供宝贵思路。