Franek W R, Horowitz S, Stansberry L, Kazzaz J A, Koo H C, Li Y, Arita Y, Davis J M, Mantell A S, Scott W, Mantell L L
CardioPulmonary Research Institute, Winthrop University Hospital, SUNY-Stony Brook School of Medicine, Mineola, New York 11501, USA.
J Biol Chem. 2001 Jan 5;276(1):569-75. doi: 10.1074/jbc.M004716200.
It has previously been shown that hyperoxia induces nonapoptotic cell death in cultured lung epithelial cells, whereas hydrogen peroxide (H(2)O(2)) and paraquat cause apoptosis. To test whether pathways leading to oxidative apoptosis in epithelial cells are sensitive to molecular O(2), A549 cells were exposed to 95% O(2) prior to exposure to lethal concentrations of H(2)O(2). The extent of H(2)O(2)-induced apoptosis was significantly reduced in cells preexposed to hyperoxia compared with room-air controls. Preexposure of the hyperoxia-resistant HeLa-80 cell line to 80% O(2) also inhibited oxidant-induced apoptosis, suggesting that this inhibition is not due to O(2) toxicity. Because hyperoxia generates reactive oxygen species and activates the redox-sensitive transcription factor nuclear factor kappa B (NF-kappa B), the role of antioxidant enzymes and NF-kappa B were examined in this inhibitory process. The onset of inhibition appeared to be directly related to the degradation of I kappa B and subsequent activation of NF-kappa B (either by hyperoxia or TNF-alpha), whereas no significant up-regulation of endogenous antioxidant enzyme activities was found. In addition, suppression of NF-kappa B activities by transfecting A549 cells with a dominant-negative mutant construct of I kappa B significantly augmented the extent of H(2)O(2)-induced apoptosis. These data suggest that hyperoxia inhibits oxidant-induced apoptosis and that this inhibition is mediated by NF-kappa B.
先前的研究表明，高氧可诱导培养的肺上皮细胞发生非凋亡性细胞死亡，而过氧化氢（H₂O₂）和百草枯则会导致细胞凋亡。为了测试上皮细胞中导致氧化凋亡的途径是否对分子氧（O₂）敏感，在将A549细胞暴露于致死浓度的H₂O₂之前，先将其暴露于95%的O₂环境中。与在室温空气中的对照细胞相比，预先暴露于高氧环境中的细胞中，H₂O₂诱导的凋亡程度显著降低。将抗高氧的HeLa - 80细胞系预先暴露于80%的O₂环境中，也能抑制氧化剂诱导的细胞凋亡，这表明这种抑制作用并非由于O₂毒性所致。由于高氧会产生活性氧并激活对氧化还原敏感的转录因子核因子κB（NF - κB），因此在这一抑制过程中对抗氧化酶和NF - κB的作用进行了研究。抑制作用的起始似乎与IκB的降解以及随后NF - κB的激活直接相关（无论是由高氧还是肿瘤坏死因子α [TNF - α] 引起），而未发现内源性抗氧化酶活性有显著上调。此外，用IκB的显性负性突变构建体转染A549细胞来抑制NF - κB活性，可显著增强H₂O₂诱导的细胞凋亡程度。这些数据表明，高氧可抑制氧化剂诱导的细胞凋亡，且这种抑制作用是由NF - κB介导的。
