基于Aurora/VEGFR靶点的新型小分子化合物Z1506抗肿瘤作用及机制研究

Anti-angiogenesis has been considered as a promising approach for anti-cancer therapy since 1970s. Although some VEGFR signal targeted drugs have been approved for clinical use, their utility is limited by associated toxicities, low efficiency or resistance to such therapy. By evaluating the inhibitory effect of a novel series of Pyrazolobenzodiazepine derivatives on VEGFR-2 activity, we found compound Z1506 exhibited the highest VEGFR-2 inhibitory potency, thus inhibiting tumor angiogenesis efficiently. The in vivo anti-tumor efficacy of Z1506 was evaluated on hepatocarcinoma and gastric cancer xenografts in a parallel comparison with another multikinase inhibitor sorafenib. Z1506 demonstrated superior efficacy and low toxicity profile over sorafenib in both test models with 80% tumor growth inhibition and tumor regression in hepatocarcinoma xenografts. Intriguingly, Z1506 abrogated the catalytic activities of Aurora kinases and led to an obvious G2/M phase arrest, thus suppressed the proliferation of tumor cells in vitro. Here, we will further evaluate the anti-tumor effect of Z1506 in vitro and in vivo systematically, demonstrate the synergistic effects between anti-angiogenesis and Aurora kinases inhibition activity of Z1506, investigate the potential targets that play important roles in the anti-tumor effect of Z1506. We hope that our study will provide the molecular theoretical basis for combination of VEGFR and Aurora inhibitors in clinic and the development of novel small molecular inhibitors targeting these two kinase families.

抗肿瘤新生血管生成是一个备受关注的肿瘤治疗领域，目前临床上使用的肿瘤新生血管抑制剂虽然具有显著的肿瘤治疗作用，但耐药、毒副作用大等问题很大程度地限制了该类药物的广泛应用。我们在前期研究中发现，具有全新结构的小分子化合物Z1506能够显著抑制VEGFR-2活性，有效抑制肿瘤新生血管生成。Z1506对肝癌和胃癌裸小鼠移植瘤具有非常显著的实验治疗作用，对肝癌的治愈率甚至达到80％，而且毒副作用明显小于临床抗肝癌靶向药物索拉菲尼，显示了很好的应用前景。进一步研究发现，Z1506还对Aurora激酶具有明显的抑制作用，从而诱导细胞发生周期阻滞，有效抑制肿瘤细胞增殖。本项目将在此基础上，系统评价Z1506的体内外抗肿瘤活性，明确抑制肿瘤新生血管生成和Aurora激酶所产生的协同效应是Z1506抗肿瘤活性发挥的重要环节，寻找其中发挥关键作用的蛋白和信号通路，为抗肿瘤药物的研发提供全新的思路。

肿瘤分子靶向治疗在癌症治疗的临床实践中取得了显著的疗效，把癌症的治疗推向了一个前所未有的新阶段。单靶点的分子靶向药物具有疗效显著、毒副作用低的特点，但是临床应用发现此类药物也存在抗瘤谱窄、疗效个体化差异显著、容易产生耐药等问题。因此将作用于不同靶点的分子靶向药物进行联用或者开发多靶点抑制剂成为解决上述问题的有效途径之一。本项目研究对象Z1506，是一个具有全新结构的小分子化合物，对于Aurora激酶和VEGFR-2激酶具有高活性、高选择性的抑制作用。体内外抗肿瘤药效活性评价结果表明，Z1506对胃癌和肝癌裸小鼠移植瘤具有非常显著的实验治疗作用，治愈率高达到80-90％，而且毒副作用明显小于临床抗肝癌靶向药物索拉菲尼，显示了很好的应用前景。分子机制研究发现，Z1506通过抑制Aurora激酶，引起细胞内H2AX、p-KAP1、p-ATM和p-Chk2表达增加，DNA发生双链断裂，导致细胞有丝分裂进程受阻，最终发生凋亡，因此Z1506对肿瘤细胞具有显著的杀伤作用；同时Z1506通过抑制VEGFR-2激酶，有效抑制肿瘤新生血管生成，破坏肿瘤生长微环境，从而显著抑制肿瘤生长。因此，Z1506通过抑制Aurora激酶和肿瘤新生血管生成所产生的协同效应发挥显著的抗肿瘤作用，确证同时靶向肿瘤发生发展的两个重要环节：“细胞增殖”和“肿瘤微环境”治疗肿瘤这一策略的可行性和有效性，为该类药物的开发提供了实验基础和理论依据，为抗肿瘤药物的研发提供全新的思路。