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Abstract：
Active glycolysis and glutaminolysis provide bioenergetic stability of cancer cells in physiological conditions. Under hypoxia, metabolic and mitochondrial disorders, or pharmacological treatment, a deficit of key metabolic substrates may become life-threatening to cancer cells. We analysed the effects of mitochondrial uncoupling by FCCP on the respiration of cells fed by different combinations of Glc, Gal, Gln and Pyr. In cancer PC12 and HCT116 cells, a large increase in O2 consumption rate (OCR) upon uncoupling was only seen when Gln was combined with either Glc or Pyr. Inhibition of glutaminolysis with BPTES abolished this effect. Despite the key role of Gln, addition of FCCP inhibited respiration and induced apoptosis in cells supplied with Gln alone or Gal/Gln. For all substrate combinations, amplitude of respiratory responses to FCCP did not correlate with Akt, Erk and AMPK phosphorylation, cellular ATP, and resting OCR, mitochondrial Ca(2+) or membrane potential. However, we propose that proton motive force could modulate respiratory response to FCCP by regulating mitochondrial transport of Gln and Pyr, which decreases upon mitochondrial depolarisation. As a result, an increase in respiration upon uncoupling is abolished in cells, deprived of Gln or Pyr (Glc). Unlike PC12 or HCT116 cells, mouse embryonic fibroblasts were capable of generating pronounced response to FCCP when deprived of Gln, thus exhibiting lower dependence on glutaminolysis. Overall, the differential regulation of the respiratory response to FCCP by metabolic environment suggests that mitochondrial uncoupling has a potential for substrate-specific inhibition of cell function, and can be explored for selective cancer treatment.
摘要：
活性糖酵解和谷氨酰胺分解提供了癌细胞在生理条件下的生物能量稳定性。在缺氧下，代谢和线粒体疾病，或药物治疗，关键代谢底物的缺乏可能会危及癌细胞的生命.我们分析了FCCP线粒体解偶联对不同Glc组合喂养的细胞呼吸的影响，Gal,Gln和Pyr.在癌症PC12和HCT116细胞中，只有当Gln与Glc或Pyr结合使用时，解偶联时O2消耗率（OCR）才会大大增加。用BPTES抑制谷氨酰胺分解消除了这种作用。尽管Gln发挥了关键作用,在单独提供Gln或Gal/Gln的细胞中,添加FCCP抑制呼吸并诱导细胞凋亡。对于所有基材组合，FCCP的呼吸反应幅度与Akt无关，Erk和AMPK磷酸化，细胞ATP,和休息OCR，线粒体Ca（2+）或膜电位。然而,我们认为质子动力可以通过调节Gln和Pyr的线粒体转运来调节对FCCP的呼吸反应，线粒体去极化后减少。因此,在细胞中，解偶联时呼吸的增加被取消，被剥夺了Gln或Pyr（Glc）。与PC12或HCT116电池不同，小鼠胚胎成纤维细胞能够在剥夺Gln时对FCCP产生明显的反应，因此对谷氨酰胺分解的依赖性较低。总的来说,代谢环境对FCCP的呼吸反应的差异调节表明，线粒体解偶联具有底物特异性抑制细胞功能的潜力，并且可以探索选择性癌症治疗。
