Xia Juan, Guo Shiwei, Fang Tao, Feng Du, Zhang Xingli, Zhang Qingyu, Liu Jie, Liu Bin, Li Mingyi, Zhu Runzhi
Laboratory of Regenerative Medicine, Department of Hepatobiliary Surgery, Affiliated Hospital of Guangdong Medical College, Zhanjiang 524001, China.
Tumor Immunology and Gene Therapy Center, Eastern Hepatobiliary Surgery Hospital, The Second Military Medical University, Shanghai 200433, China.
Food Chem Toxicol. 2014 Apr;66:7-13. doi: 10.1016/j.fct.2014.01.014. Epub 2014 Jan 18.
Dihydromyricetin (DHM), a bioactive flavonoid compound extracted from the stems and leaves of Ampelopsis grossedentata, has oxidation resistance, anti-tumor and free radical scavenging capabilities. In this study, we found that DHM-induced autophagy inhibited the cell proliferation in HepG2 cells. The transmission electron microscopy results showed that DHM induced significantly autophagosome characteristics like autophagolysosome containing degraded cellular content. GFP labled LC3 plasma transfection showed that LC3 largely diffused to punctate structures with DHM treatment, while lysosomal-rich/acidic compartments detected using LysoTracker Red staining. In addition, DHM promoted the expressions of LC3-II and Beclin-1 in a dose- and time-dependent manner. Further study showed that DHM suppressed the activation of mTOR (mammalian targets of rapamycin) involved in regulating its upstream signaling pathways including extracellular signal-regulated kinase 1/2 (ERK1/2), AMPK (AMP-activated kinase) and class III phosphatidylinositol 3-kinase/phosphoinositide-dependent protein kinase 1/protein kinase B (PI3K/PDK 1/Akt) pathways. Taken together, all the results demonstrated that DHM-induced autophagy inhibited the cell proliferation in HepG2 cells, the possible mechanism involved in inhibition of mTOR activation and regulating the related upstream signaling pathways.
二氢杨梅素（DHM）是从显齿蛇葡萄的茎叶中提取的一种生物活性黄酮类化合物，具有抗氧化、抗肿瘤和清除自由基的能力。在本研究中，我们发现DHM诱导的自噬抑制了HepG2细胞的增殖。透射电子显微镜结果显示，DHM显著诱导了自噬体特征，如含有降解细胞内容物的自噬溶酶体。GFP标记的LC3质粒转染显示，经DHM处理后，LC3大量扩散为点状结构，同时使用LysoTracker Red染色检测到富含溶酶体/酸性区室。此外，DHM以剂量和时间依赖性方式促进LC3-II和Beclin-1的表达。进一步研究表明，DHM抑制了参与调节其上游信号通路的mTOR（雷帕霉素哺乳动物靶点）的激活，这些上游信号通路包括细胞外信号调节激酶1/2（ERK1/2）、AMPK（AMP激活的激酶）和III类磷脂酰肌醇3激酶/磷脂酰肌醇依赖性蛋白激酶1/蛋白激酶B（PI3K/PDK 1/Akt）通路。综上所述，所有结果表明，DHM诱导的自噬抑制了HepG2细胞的增殖，其可能机制涉及抑制mTOR激活和调节相关上游信号通路。
