Pan Xinchao, Wang Xunde, Lei Weiwei, Min Lihua, Yang Yanan, Wang Xin, Song Jianguo
Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, P.R. China.
Hepatology. 2009 Nov;50(5):1577-87. doi: 10.1002/hep.23156.
Nitric oxide (NO) is a multifunctional regulator that is implicated in various physiological and pathological processes. Here we report that administration of NO donor S-nitroso-N-acetylpenicillamine (SNAP) inhibited transforming growth factor-beta1 (TGF-beta1)-induced epithelial-to-mesenchymal transition (EMT) and apoptosis in mouse hepatocytes. Overexpression of inducible NO synthase (iNOS) by transfection of the iNOS-expressing vector, which increased NO production, also inhibited the TGF-beta1-induced EMT and apoptosis in these cells. Treatment of cells with proinflammatory mediators, including tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and interferon (IFN)-gamma, which increased the endogenous NO production, produced the same inhibitory effect. Furthermore, exogenous NO donor SNAP treatment caused a decrease in the intracellular adenosine triphosphate (ATP) levels. Consistently, depletion of intracellular ATP by mitochondrial uncoupler carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP) inhibited the TGF-beta1-induced EMT and apoptosis, suggesting that an NO-induced decrease of ATP involved in the NO-mediated inhibition of TGF-beta1-induced EMT and apoptosis. NO and FCCP also inhibited TGF-beta1-induced STAT3 activation, suggesting that signal transducer and activator of transcription 3 inactivation is involved in the NO-induced effects on TGF-beta1-induced EMT and apoptosis.
Our study indicates that NO plays an important role in the inhibition of TGF-beta1-induced EMT and apoptosis in mouse hepatocytes through the downregulation of intracellular ATP levels. The data provide an insight into the in vivo mechanisms on the function of NO during the processes of both EMT and apoptosis.
一氧化氮（NO）是一种多功能调节剂，参与多种生理和病理过程。在此我们报告，给予NO供体S-亚硝基-N-乙酰青霉胺（SNAP）可抑制转化生长因子-β1（TGF-β1）诱导的小鼠肝细胞上皮-间质转化（EMT）和凋亡。通过转染表达诱导型一氧化氮合酶（iNOS）的载体使iNOS过表达，增加了NO的产生，也抑制了TGF-β1诱导的这些细胞的EMT和凋亡。用促炎介质处理细胞，包括肿瘤坏死因子（TNF）-α、白细胞介素（IL）-1β和干扰素（IFN）-γ，增加了内源性NO的产生，产生了相同的抑制作用。此外，外源性NO供体SNAP处理导致细胞内三磷酸腺苷（ATP）水平降低。一致地，线粒体解偶联剂羰基氰化物对三氟甲氧基苯腙（FCCP）耗尽细胞内ATP抑制了TGF-β1诱导的EMT和凋亡，表明NO诱导的ATP减少参与了NO介导的对TGF-β1诱导的EMT和凋亡的抑制。NO和FCCP也抑制了TGF-β1诱导的信号转导和转录激活因子3（STAT3）的激活，表明信号转导和转录激活因子3失活参与了NO对TGF-β1诱导的EMT和凋亡的影响。
我们的研究表明，NO通过下调细胞内ATP水平在抑制TGF-β1诱导的小鼠肝细胞EMT和凋亡中起重要作用。这些数据为EMT和凋亡过程中NO功能的体内机制提供了见解。
