Wang Yuexia, Liu Yanan, Liu Xiaofang, Jiang Liping, Yang Guang, Sun Xiance, Geng Chengyan, Li Qiujuan, Yao Xiaofeng, Chen Min
Department of Preventive Medicine, Dalian Medical University, 9 W Lvshun South Road, Dalian 116044, China.
Liaoning Anti-Degenerative Diseases Natural Products Engineering Research Center, Dalian Medical University, 9 W Lvshun South Road, Dalian 116044, China.
Toxins (Basel). 2015 Aug 6;7(8):3030-44. doi: 10.3390/toxins7083030.
Citreoviridin (CIT) is a mycotoxin derived from fungal species in moldy cereals. In our previous study, we reported that CIT stimulated autophagosome formation in human liver HepG2 cells. Here, we aimed to explore the relationship of autophagy with lysosomal membrane permeabilization and apoptosis in CIT-treated cells. Our data showed that CIT increased the expression of LC3-II, an autophagosome biomarker, from the early stage of treatment (6 h). After treatment with CIT for 12 h, lysosomal membrane permeabilization occurred, followed by the release of cathepsin D in HepG2 cells. Inhibition of autophagosome formation with siRNA against Atg5 attenuated CIT-induced lysosomal membrane permeabilization. In addition, CIT induced collapse of mitochondrial transmembrane potential as assessed by JC-1 staining. Furthermore, caspase-3 activity assay showed that CIT induced apoptosis in HepG2 cells. Inhibition of autophagosome formation attenuated CIT-induced apoptosis, indicating that CIT-induced apoptosis was autophagy-dependent. Cathepsin D inhibitor, pepstatin A, relieved CIT-induced apoptosis as well, suggesting the involvement of the lysosomal-mitochondrial axis in CIT-induced apoptosis. Taken together, our data demonstrated that CIT induced autophagy-dependent apoptosis through the lysosomal-mitochondrial axis in HepG2 cells. The study thus provides essential mechanistic insight, and suggests clues for the effective management and treatment of CIT-related diseases.
黄绿青霉素（CIT）是一种从霉变谷物中的真菌物种衍生而来的霉菌毒素。在我们之前的研究中，我们报道了CIT刺激人肝癌HepG2细胞中自噬体的形成。在此，我们旨在探讨自噬与CIT处理细胞中溶酶体膜通透性和细胞凋亡之间的关系。我们的数据表明，从处理早期（6小时）开始，CIT就增加了自噬体生物标志物LC3-II的表达。用CIT处理12小时后，HepG2细胞中发生溶酶体膜通透性增加，随后组织蛋白酶D释放。用针对Atg5的小干扰RNA抑制自噬体形成可减弱CIT诱导的溶酶体膜通透性增加。此外，通过JC-1染色评估，CIT诱导线粒体跨膜电位崩溃。此外，caspase-3活性测定表明，CIT诱导HepG2细胞凋亡。抑制自噬体形成可减弱CIT诱导的细胞凋亡，表明CIT诱导的细胞凋亡是自噬依赖性的。组织蛋白酶D抑制剂胃蛋白酶抑制剂A也可减轻CIT诱导的细胞凋亡，提示溶酶体-线粒体轴参与了CIT诱导的细胞凋亡。综上所述，我们的数据表明，CIT通过溶酶体-线粒体轴在HepG2细胞中诱导自噬依赖性细胞凋亡。该研究因此提供了重要的机制见解，并为CIT相关疾病的有效管理和治疗提供了线索。
