BACKGROUND Escape from apoptosis is an important hallmark of tumor progression and drug resistance in cancer cells. It is well demonstrated that over-expression of human wtp53 in Saccharomyces cerevisiae induces apoptosis by directly targeting the mitochondria. In this study, we showed that how S.cerevisiae escaped from p53 induced apoptosis in the presence of a fermentable carbon source (sucrose), but not on non-fermentable carbon source (glycerol). METHODS Mitochondrial fractions from yeast cultures grown in the presence of sucrose or glycerol with and without p53 expression were fractionated and analyzed by LC-MS/MS. Differentially expressed proteins were studied and detailed biochemical analysis for selected proteins was performed.The effect of mitochondrial HXK-2 over-expression induced by p53 in sucrose grown cells on cell survival was evaluated using gene deletion/tagging, co-localisation and mitochondrial ROS detection. RESULTS We observe that mitochondria isolated from p53 over-expressing cells accumulate Pentose phosphate Pathway (PPP) enzymes including glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) which led to enhanced mitochondrial NADPH production only when cells are cultured in sucrose but not glycerol. In contrast, mitochondria isolated from Δhxk2 p53 over-expressing cells grown in sucrose did not accumulate G6PDH and 6PGDH and resulted in defective growth. CONCLUSIONS Enhanced association of HXK2 with the mitochondria with the concomitant accumulation of G6PDG and 6PGDH results in increased NADPH that scavenges ROS and provides resistance to apoptosis. GENERAL SIGNIFICANCE Given the extensive similarity of aerobic glycolysis between humans and yeast, the phenomena described here could as well be responsible for the escape of apoptosis in cancer cells.

中文翻译：

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线粒体葡萄糖6磷酸脱氢酶和6磷酸葡萄糖酸脱氢酶消除了酵母模型中的p53诱导的细胞凋亡：癌细胞凋亡抗性的可能含义。

背景技术逃避凋亡是癌细胞中肿瘤进展和耐药性的重要标志。充分证明，在酿酒酵母中人wtp53的过表达通过直接靶向线粒体来诱导细胞凋亡。在这项研究中，我们表明酿酒酵母如何在存在可发酵碳源（蔗糖）的情况下从p53逃逸而诱导凋亡，而不是在不可发酵碳源（甘油）的情况下。方法分离存在和不存在p53表达的蔗糖或甘油条件下生长的酵母培养物中的线粒体级分，并通过LC-MS / MS进行分析。研究了差异表达的蛋白质，并对选定的蛋白质进行了详细的生化分析。使用基因缺失/标记，共定位和线粒体ROS检测评估了蔗糖生长细胞中p53诱导的线粒体HXK-2过表达对细胞存活的影响。结果我们观察到，从p53过表达细胞中分离出的线粒体会积累磷酸戊糖途径（PPP）酶，包括葡萄糖-6-磷酸脱氢酶（G6PDH）和6-磷酸葡萄糖酸脱氢酶（6PGDH），只有在培养细胞后才会导致线粒体NADPH产生增加在蔗糖中而不在甘油中。相反，从蔗糖中生长的过量表达Δhxk2p53的细胞中分离出的线粒体不会积聚G6PDH和6PGDH，导致生长缺陷。结论HXK2与线粒体的结合增强，同时伴有G6PDG和6PGDH的积累导致NADPH增加，从而清除ROS并提供对细胞凋亡的抵抗力。一般意义鉴于人类和酵母之间有氧糖酵解的广泛相似性，此处描述的现象也可能导致癌细胞凋亡的逃逸。