瘤果黑种草子主要抗胃癌活性成分作用机制研究

Gastric cancer (GC), one of the most common malignant tumors in China, is supposed to present drug resistance to traditional chemotherapeutics which usually have overt side effects. Therefore, it is very important to explore high effective natural medicine against GC with low toxicity for clinical application. In the previous study, we found that α-hederin extracted from the seeds of Nigella glandulifera Freynet Sint. could inhibit proliferation and induce apoptosis, down-regulate glutathione (GSH), and strengthen the inhibition effect of thymoquinone (TQ) in GC cells. We speculate that GSH depletion could cause an accumulation of ROS, and stimulate the Caspase-cascade mediated apoptosis of GC cells. On the other hand, ROS could suppress the expression of NF-κB resulting in the inhibition of proliferation and invasion. What’s more, the down-regulation of NF-κB, which is a key downstream molecular of PTEN signaling pathway, plays a pivotal role in the relationship of α-hederin and TQ. In the present research, the drug-resistant GC cell lines will be established and the models of human gastric carcinoma in nude mice would be made by orthotopic transplantation. The synthesis of GSH in the cancer cell lines and models would be promoted and interfered by specific promoter and inhibitor. Based on these, the expression of GSH and related proteins in GC cell lines would be detected in the present of α-hederin to verify the essential roles of α-hederin in the regulation of inhibiting proliferation and inducing apoptosis in tumor cells. Moreover, the effects of α-hederin on the proliferation and apoptosis of GC cells induced by TQ would also be investigated, which will provide profound foundations for further employment of Nigella glandulifera against gastric cancer in the future.

胃癌是我国最常见的恶性肿瘤之一，其常用化疗药物毒副作用大、耐药发生率高，因此寻找天然、低毒、高效药物治疗胃癌意义重大。项目组研究发现瘤果黑种草子提取物α-常春藤皂苷能抑制胃癌细胞增殖诱导凋亡、下调GSH水平、增强百里醌抗胃癌作用。我们推测，GSH耗竭引起的ROS蓄积可激发Caspase级联反应诱导胃癌细胞凋亡、下调NF-κB抑制胃癌细胞增殖与侵袭，同时NF-κB（PTEN信号通路关键分子）的下调可增强百里醌抗胃癌作用。本项目拟构建胃癌耐药细胞株和裸鼠原位移植瘤模型，应用特异性GSH合成促进和抑制技术干扰GSH合成，检测GSH及相关蛋白表达变化，从而揭示α-常春藤皂苷调控胃癌细胞增殖和凋亡具体机制，同时探讨其增强百里醌抗胃癌作用的相关机制（GSH/ROS诱导的NF-κB下调对PTEN信号通路的影响），为临床应用α-常春藤皂苷和百里醌治疗胃癌以及瘤果黑种草子的进一步开发利用提供理论依据。

胃癌是我国最常见的恶性肿瘤之一，其常用化疗药物毒副作用大、耐药发生率高。项目组前期研究发现α-常春藤皂苷能抑制胃癌细胞增殖诱导凋亡，且呈时间和浓度依赖性。本项目在前期研究基础上，成功构建胃癌耐顺铂细胞株HGC27/DDP和裸鼠原位移植瘤模型，验证α-常春藤皂苷能抑制胃癌细胞及胃癌耐药细胞增殖诱导凋亡，进一步检测了α-常春藤皂苷能引起GSH耗竭，活性氧蓄积以及线粒体膜电位下降，并检测凋亡相关蛋白及线粒体相关通路蛋白表达。同时应用GSH合成促进剂和抑制剂干扰GSH合成，验证了GSH耗竭引起的ROS蓄积可激发Caspase级联反应诱导胃癌细胞及胃癌耐药细胞凋亡，探讨了线粒体相关通路在其中的作用。本研究阐明了α-常春藤皂苷调控胃癌细胞增殖和凋亡具体机制，为临床应用α-常春藤皂苷治疗胃癌以及瘤果黑种草子的进一步开发利用提供理论依据。