毛钩藤碱通过激活CAP1调控的线粒体分裂选择性诱导肺癌细胞凋亡的分子机制研究

Lung cancer is the most common incident cancer and the leading cause of cancer death in China. It is of great significance to find novel anti-lung cancer drugs with high efficiency and low toxicity. Our preliminary experiments found that natural compound Hirsutine selectively induced apoptosis in lung cancer cells but with little toxicity in normal cells, indicating that Hirsutine has the potential to be developed as a new anti-lung cancer drug with high efficacy and low toxicity, but the molecular mechanism of its anti-lung cancer activity is not clear. Our preliminary experiments revealed that Hirsutine induces CAP1 (a protein highly expressed in lung cancer) dephosphorylation/activation, leading to mitochondrial fission, cytochrome c release and eventually apoptosis. However, the molecular mechanism by which CAP1 regulates mitochondrial fission remains unclear. The literatures and our preliminary results suggest that CAP1-regulated mitochondrial fission depends on its actin depolymerization activity through interaction with cofilin at the mitochondrial fission site, gradually shortening the length of F-actin, causing the contraction of the complex ring, and finally leading to mitochondrial fission. In this proposal, we aim to clarify Hirsutine’s selective anti-lung cancer activity and elucidate the molecular mechanism underlying the anti-lung cancer effects of Hirsutine through activation of CAP1-mediated mitochondrial fission. Our study will strengthen the understanding of mitochondrial fission, and provide novel targets and intervention strategy for lung cancer treatment.

肺癌是我国第一大癌症，寻找新的高效低毒抗肺癌药物具有重大意义。我们前期筛选出天然植物来源毛钩藤碱(Hirsutine)具有良好的选择性抗肺癌活性，具有开发成为高效低毒的抗肺癌新药潜力，但其选择性抗肺癌分子机制尚不明确。我们预实验发现毛钩藤碱可去磷酸化激活肺癌高表达的CAP1，诱发CAP1依赖的线粒体分裂，导致细胞色素C释放和细胞凋亡，从而发挥选择性抗肺癌作用。但CAP1调控线粒体分裂的机制尚不清楚，综合文献和我们前期研究结果提示CAP1可能是在线粒体分裂位点与Cofilin相互作用解聚F-actin，逐渐缩短F-actin长度，引起分裂复合物环收缩，最终缢裂线粒体。本项目拟在细胞系、动物、患者原代细胞多层次进一步明确毛钩藤碱的选择性诱导肺癌细胞凋亡作用，并阐明毛钩藤碱激活CAP1调控线粒体分裂的分子机制。本项目将加深对线粒体分裂的理论认识，为肺癌的治疗提供新的靶点和干预方法。

肺癌是我国第一大癌症，寻找新的高效低毒抗肺癌药物具有重大意义。我们前期筛选出天然植物来源毛钩藤碱(Hirsutine)具有良好的选择性抗肺癌活性，具有开发成为高效低毒的抗肺癌新药潜力，但其选择性抗肺癌分子机制尚不明确。我们深入研究发现Hirsutine可体内外激活肺癌高表达的ROCK1, 诱导下游PTEN/PI3K/Akt/GSK3β通路激活，导致线粒体渗透性转换孔开放，诱发线粒体损伤途径细胞凋亡，具有良好的体内抗肺癌作用。另外我们还发现Hirsutine可诱导ROCK1下游分子CAP1去磷酸化。我们发现CAP1是潜在的肺癌治疗靶点，在肺癌高表达，与患者预后负相关，CAP1可与Actin和Cofilin一起转位到细胞核中，直接与CDK9/Pol II相互作用，促进Pol II（Ser2）磷酸化激活，增加Pol II介导的转录，促进蛋白质合成，加速肺癌细胞周期进程，并在动物体内证实了CAP1的促进肺癌增殖的效应，验证了上述机制。通过本项目研究，我们共计发表SCI论文2篇，包括Oncogene (IF:9.867)，Cell Death and Disease (IF:8.469)，获得授权发明专利1项。我们的研究可为肺癌的治疗提供潜在的靶点和治疗药物。