Impaired mitophagy activates mtROS/HIF-1α interplay and increases cancer aggressiveness in gastric cancer cells under hypoxia
Impaired mitophagy activates mtROS/HIF-1α interplay and increases cancer aggressiveness in gastric cancer cells under hypoxia
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DOI：
10.3892/ijo.2016.3359
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发表时间：
2016-04-01
影响因子：
5.2
通讯作者：
Noshiro, Hirokazu
中科院分区：
文献类型：
--
作者：
Shida, Masaaki;Kitajima, Yoshihiko;Noshiro, Hirokazu
线粒体自噬（mitophagy）是一种选择性的自噬形式，是排除受应激（包括缺氧）损伤的线粒体的关键步骤。本研究旨在确定线粒体自噬的完整性是否影响缺氧条件下GC细胞线粒体活性氧（mtROS）的产生、缺氧诱导因子(HIF)-1 α的表达和侵袭性特征。本研究对3株GC细胞系44As3、58As9和MKN45进行了研究。缺氧诱导3种GC细胞系HIF-1 α表达，44As3和58As9细胞中HIF-1 α表达高于MKN45细胞。44As3和58As9细胞在缺氧条件下的存活和侵袭能力明显强于MKN45细胞。此外，mtROS在44As3和58As9细胞中以时间依赖性的方式积累，而在MKN45细胞中则没有。活性氧清除剂n -乙酰- l-半胱氨酸（NAC）处理导致HIF-1 α表达的强烈衰减，而在缺氧条件下，HIF-1 α的敲低增加了三种GC细胞系的活性氧产生。这些结果表明，mtROS/HIF-1 α相互作用影响缺氧诱导的癌症侵袭性。通过LC3-I/II转化、SQSTM1/p62降解和特异性荧光标记来评估线粒体自噬，表明缺氧诱导的线粒体自噬仅在MKN45细胞中观察到，而在其他两个细胞系中该过程被破坏。在缺氧的MKN45细胞中，自噬抑制剂氯喹反而增加了HIF-1a的表达、mtROS的产生、细胞存活和侵袭。本研究揭示了一种新的机制，在缺氧条件下，线粒体自噬的完整性可能通过mtROS/HIF-1 α相互作用决定胃癌细胞的侵袭性。
Mitochondrial autophagy (mitophagy) is a selective form of autophagy and a critical step in excluding mitochondria damaged by stress, including hypoxia. This study aimed to determine whether the integrity of mitophagy affected production of the mitochondrial reactive oxygen species (mtROS), hypoxia inducible factor (HIF)-1 alpha expression and aggressive characteristics in GC cells under hypoxia. Three GC cell lines, 44As3, 58As9 and MKN45, were investigated in this study. HIF-1 alpha expression was induced in the three GC cell lines under hypoxia, with higher expression observed in 44As3 and 58As9 cells compared with MKN45 cells. Cell survival and invasion abilities under hypoxia were significantly stronger in 44As3 and 58As9 cells than MKN45 cells. Moreover, mtROS accumulated in a time-dependent manner in 44As3 and 58As9 cells, but not in MKN45 cells. ROS scavenger N-acetyl-L-cysteine (NAC) treatment resulted in strong attenuation of HIF-1 alpha expression, whereas HIF-1 alpha knockdown increased ROS production in the three GC cell lines under hypoxia. These results suggested that the mtROS/HIF-1 alpha interplay affected the hypoxia-induced cancer aggressiveness. Assessment of mitophagy by LC3-I/II conversion, SQSTM1/p62 degradation and specific fluorescence markers demonstrated that hypoxiainduced mitophagy was observed only in MKN45 cells, while the process was impaired in the other two cell lines. Treatment with the autophagy inhibitor chloroquine conversely increased HIF-1a expression, mtROS generation, cell survival and invasion in hypoxic MKN45 cells. The present study revealed a novel mechanism in which the integrity of mitophagy might determine cancer aggressiveness via mtROS/HIF-1 alpha interplay in GC cells under hypoxic conditions.