Cui Haiyan, Wu Shufen, Shang Yunfei, Li Zhenjing, Chen Mianhua, Li Fengjuan, Wang Changlu
Key Laboratory of Food Nutrition and Safety, Ministry of Education, School of Food Engineering and Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, PR China.
Food Funct. 2016 Mar;7(3):1616-27. doi: 10.1039/c6fo00027d.
Since the strong antineoplastic potential against A549 cells of Pleurotus nebrodensis polysaccharide (PN50G) in vitro has been proven previously, the definitive mechanism of PN50G-induced apoptosis in A549 cells in vivo was further investigated. All the results indicated that PN50G significantly suppressed tumor growth in A549 tumor-bearing mice. Tumor cells treated with PN50G were arrested in the G0/G1 phase, and marked changes in the expression of cell cycle-related proteins, including cyclin D1, cyclin A and cyclin B1, were observed. Moreover, western blotting analysis indicated that PN50G triggered the mitochondrial apoptotic pathway, for an increased Bax/Bcl-2 ratio, release of cytochrome c, cleavage of caspase-3 and PRPP in A549 tumor cells were observed. And the decrease in the expression of the translation related protein P70S6K was observed, because PN50G activated AMPK phosphorylation, but inhibited PI3K/AKT phosphorylation and suppressed the activation of the mammalian target of rapamycin (mTOR) induced by PN50G. In vivo imaging was performed on tumor-bearing mice, and the results indicated that PN50G significantly increased the intracellular levels of reactive oxygen species (ROS). Furthermore, it indicated that PN50G promoted the protein expression of Beclin 1 and LC-3 in a dose-dependent manner. All the results suggested that PN50G-mediated apoptosis and autophagy of A549 tumor cells in vivo mainly involved in the mitochondrial pathway and the AMPK/PI3K/mTOR pathway.
由于前期已证实白灵侧耳多糖（PN50G）在体外对A549细胞具有强大的抗肿瘤潜力，因此进一步研究了PN50G在体内诱导A549细胞凋亡的确切机制。所有结果表明，PN50G可显著抑制A549荷瘤小鼠的肿瘤生长。用PN50G处理的肿瘤细胞停滞于G0/G1期，并且观察到细胞周期相关蛋白（包括细胞周期蛋白D1、细胞周期蛋白A和细胞周期蛋白B1）表达的显著变化。此外，蛋白质印迹分析表明，PN50G触发了线粒体凋亡途径，因为在A549肿瘤细胞中观察到Bax/Bcl-2比值增加、细胞色素c释放、半胱天冬酶-3和PRPP裂解。并且观察到翻译相关蛋白P70S6K的表达下降，因为PN50G激活了AMPK磷酸化，但抑制了PI3K/AKT磷酸化，并抑制了PN50G诱导的雷帕霉素哺乳动物靶标（mTOR）的激活。对荷瘤小鼠进行了体内成像，结果表明PN50G显著提高了细胞内活性氧（ROS）水平。此外，结果表明PN50G以剂量依赖性方式促进了Beclin 1和LC-3的蛋白表达。所有结果表明，PN50G在体内介导的A549肿瘤细胞凋亡和自噬主要涉及线粒体途径和AMPK/PI3K/mTOR途径。
