Toosendanin靶向Wnt信号通路抑制肿瘤转移活性及作用机制研究

Metastasis is the leading cause of mortality in cancer patients. Thus, it is now in urgent need in clinical cancer therapy to further illuminate the mechanism of tumor metastasis and develop highly potent and specific anti-metastasis agents aiming at the promising molecular target. Wnt/β-catenin signaling is crucially involved in tumor metastasis, making it the potent therapeutic target of anti-metastasis drugs. We firstly identified Toosendanin, a tetranortriterpenoid compound, as a novel inhibitor of Wnt signaling with remarkable tumor metastasis inhibitory activity in vitro. Further results showed that Toosendanin downregulated the endogenous target genes of Wnt signaling and significantly inhibited tumor metastasis in vivo. In the present study, we will investigate the mechanisms and target of Toosendanin targeting Wnt signaling with biochemistry and chemical biology techniques. Further we will perform pharmacological investigation to evaluate the anti-metastasis activity of Toosendanin in vitro and in vivo and illuminate the molecular mechanism of Toosendanin inhibiting metastasis. This study will provide theoretical basis for the devlopment of Toosendanin as anti-metastasis agent and may reveal novel mechanisms underlying Wnt signaling -mediated tumor metastasis.

转移是恶性肿瘤治疗失败的主要原因，肿瘤转移机制的深入研究，选择合适的分子靶点并筛选到高效特异的药物从而抑制肿瘤转移是目前肿瘤治疗急需解决的热点问题。Wnt/β-catenin信号通路与肿瘤转移密切相关，是抗肿瘤转移药物潜在的重要靶标。我们首次发现四降三萜类化合物Toosendanin具有显著的Wnt信号通路及肿瘤转移抑制活性。进一步研究显示Toosendanin抑制肿瘤细胞内Wnt靶基因的表达并显著抑制体内肿瘤转移，具有潜在的开发价值。本研究拟利用药理学以及化学生物学手段，深入研究Toosendanin抑制Wnt信号通路的作用机制和分子靶点，评价Toosendanin抑制肿瘤转移的体内外活性和分子机制，解析Toosendanin如何通过靶向Wnt信号通路发挥转移抑制活性。本项目将为Toosendanin在抗肿瘤转移药物中的可能应用提供理论基础, 并有望揭示Wnt信号通路调控肿瘤转移的新机制

转移是恶性肿瘤治疗失败的主要原因，Wnt/β-Catenin信号通路与肿瘤转移密切相关，是抗肿瘤转移药物潜在的重要靶标。天然产物是抗肿瘤药物的重要来源，因此从结构多样的天然产物中筛选具有新颖结构的Wnt信号通路抑制剂并阐明其转移抑制活性及分子作用机制，对于靶向Wnt信号通路的抗肿瘤药物研发和肿瘤治疗具有重要的意义。本研究对前期筛选中发现的具有Wnt信号通路抑制活性的Toosendanin的体内外转移抑制活性及作用机制进行了深入的探讨。.双荧光素酶报告基因体系检测发现Toosendanin对Wnt3a诱导的Wnt信号通路的激活以及结直肠肿瘤细胞内异常激活的Wnt信号通路均具有显著的抑制活性。蛋白免疫印迹实验发现Toosendanin显著抑制结肠肿瘤细胞中Wnt信号通路下游靶基因的表达。进一步机制研究发现Toosendanin通过增加GSK的活性促进β-Catenin的磷酸化及其降解，从而抑制Wnt信号通路。Toosendanin靶向Wnt信号通路活性抑制肿瘤转移的分子机制主要为：首先，Toosendanin抑制Wnt信号通路从而调控其下游与肿瘤转移相关基因的表达。其次，Toosendanin促进了E-Cadherin的表达及β-Catenin/E-Cadherin复合体的形成，增加细胞间的黏附，以及Wnt信号通路活性的进一步降低。此外，Wnt信号通路下游靶基因Axin2的降低导致GSK的核输出减少，从而GSK对Snail的磷酸化及降解增加，诱导E-Cadherin的表达抑制肿瘤转移。体外划痕和Oris™ Cell Migration Assay检测结果表明Toosendanin显著抑制结肠肿瘤细胞的迁移活性。体内结果显示Toosendanin对肿瘤细胞的体内肺转移及生长均具有良好的抑制活性，Western blot检测结果显示Toosendanin抑制肿瘤组织内Wnt信号通路活性并调控肿瘤转移相关基因的表达。项目研究结果为Toosendanin在肿瘤转移中的可能应用奠定了理论基础。