Enhancing mitochondrial respiration suppresses tumor promoter TPA-induced PKM2 expression and cell transformation in skin epidermal JB6 cells.
Enhancing mitochondrial respiration suppresses tumor promoter TPA-induced PKM2 expression and cell transformation in skin epidermal JB6 cells.
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DOI：
10.1158/1940-6207.capr-11-0028
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发表时间：
2011-09
期刊：
影响因子：
--
通讯作者：
Zhao Y
中科院分区：
文献类型：
--
作者：
Wittwer JA;Robbins D;Wang F;Codarin S;Shen X;Kevil CG;Huang TT;Van Remmen H;Richardson A;Zhao Y
分化的细胞主要通过三羧酸循环和氧化磷酸化代谢葡萄糖以获得能量，但癌细胞依靠不同的机制来产生能量，其特征在于瓦尔堡效应，其描述了对有氧糖酵解的依赖性增加。丙酮酸激酶（PKM 2）的M2亚型负责催化有氧糖酵解的最后一步，在癌细胞中高度表达，可能有助于瓦尔堡效应。然而，PKM 2是否在早期癌症发展中起作用尚不清楚。在我们的研究中，我们试图阐明不同的线粒体呼吸底物对皮肤细胞转化和PKM 2表达的影响。用12-O-十四酰基佛波醇-13-乙酸酯（TPA）作为肿瘤促进剂，在软琼脂试验中测定小鼠皮肤表皮JB 6 P+（可促进）细胞的致瘤性。我们观察到用线粒体呼吸底物琥珀酸或苹果酸/丙酮酸预处理后细胞转化显着减少。我们观察到TPA处理的JB 6 P+细胞中PKM 2的表达和活性增加以及琥珀酸或苹果酸/丙酮酸预处理抑制了这种作用。此外，TPA处理还诱导PKM 2，而PKM 1的表达在小鼠皮肤表皮组织中在体内被抑制。与JB 6 P+细胞相比，不可促进的JB 6 P−细胞在TPA处理后PKM 2表达或活性没有增加。使用siRNA方法敲低PKM 2显著减少皮肤细胞转化。因此，我们的研究结果表明，PKM 2激活可能是一个早期事件，并在皮肤肿瘤的发生中发挥作用。
Differentiated cells primarily metabolize glucose for energy via the tricarboxylic acid cycle and oxidative phosphorylation, but cancer cells thrive on a different mechanism to produce energy, characterized as the Warburg effect, which describes the increased dependence on aerobic glycolysis. The M2 isoform of pyruvate kinase (PKM2), which is responsible for catalyzing the final step of aerobic glycolysis, is highly expressed in cancer cells and may contribute to the Warburg effect. However, whether PKM2 plays a contributing role during early cancer development is unclear. In our studies, we have made an attempt to elucidate the effects of varying mitochondrial respiration substrates on skin cell transformation and expression of PKM2. Tumorigenicity in murine skin epidermal JB6 P+ (promotable) cells was measured in a soft agar assay using 12-O-tetradecanoylphorbol-13-acetate (TPA) as a tumor promoter. We observed a significant reduction in cell transformation upon pretreatment with the mitochondrial respiration substrate succinate or malate/pyruvate. We observed that increased expression and activity of PKM2 in TPA-treated JB6 P+ cells and pretreatment with succinate or malate/pyruvate suppressed the effects. In addition, TPA treatment also induced PKM2 whereas PKM1 expression was suppressed in mouse skin epidermal tissues in vivo. In comparison with JB6 P+ cells, the nonpromotable JB6 P− cells showed no increase in PKM2 expression or activity upon TPA treatment. Knockdown of PKM2 using a siRNA approach significantly reduced skin cell transformation. Thus, our results suggest that PKM2 activation could be an early event and play a contributing role in skin tumorigenesis.