Tyrosine Phosphorylation of Lactate Dehydrogenase A Is Important for NADH/NAD+ Redox Homeostasis in Cancer Cells
Tyrosine Phosphorylation of Lactate Dehydrogenase A Is Important for NADH/NAD+ Redox Homeostasis in Cancer Cells
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DOI：
10.1128/mcb.06120-11
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发表时间：
2011-12-01
影响因子：
5.3
通讯作者：
Chen, Jing
中科院分区：
文献类型：
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作者：
Fan, Jun;Hitosugi, Taro;Chen, Jing
瓦尔堡效应描述了癌细胞中有氧糖酵解的增加和乳酸盐产生的增强。乳酸脱氢酶A（LDH-A）调节糖酵解的最后一步，产生乳酸并允许NAD（+）再生。LDH-A基因表达被认为是由HIF和Myc在癌细胞中上调，以实现增加的乳酸生产。然而，致癌信号如何激活LDH-A来调节癌细胞代谢仍不清楚。我们发现致癌受体酪氨酸激酶FGFR 1直接磷酸化LDH-A。Y10和Y83的磷酸化分别通过增强活性四聚体LDH-A的形成和LDH-A底物NADH的结合来增强LDH-A活性。此外，LDH-A的Y10磷酸化在多种人类癌细胞中是常见的，其与多种致癌酪氨酸激酶的活化相关。有趣的是，具有内源性LDH-A的稳定敲低和催化性亚型LDH-A突变体Y10 F的拯救表达的癌细胞证明通过线粒体复合物I增加呼吸以通过提供NAD（+）维持糖酵解。然而，Y10 F细胞线粒体呼吸的这种补偿性增加不足以完全维持糖酵解。Y10救援细胞在缺氧条件下显示出细胞增殖和ATP水平降低，并且在异种移植裸鼠中显示出肿瘤生长降低。我们的研究结果表明，酪氨酸磷酸化增强LDH-A酶活性，促进瓦尔堡效应和肿瘤生长，通过调节NADH/NAD（+）氧化还原稳态，代表了一个急性的分子机制，在癌细胞中的乳酸生产增加。
The Warburg effect describes an increase in aerobic glycolysis and enhanced lactate production in cancer cells. Lactate dehydrogenase A (LDH-A) regulates the last step of glycolysis that generates lactate and permits the regeneration of NAD(+). LDH-A gene expression is believed to be upregulated by both HIF and Myc in cancer cells to achieve increased lactate production. However, how oncogenic signals activate LDH-A to regulate cancer cell metabolism remains unclear. We found that the oncogenic receptor tyrosine kinase FGFR1 directly phosphorylates LDH-A. Phosphorylation at Y10 and Y83 enhances LDH-A activity by enhancing the formation of active, tetrameric LDH-A and the binding of LDH-A substrate NADH, respectively. Moreover, Y10 phosphorylation of LDH-A is common in diverse human cancer cells, which correlates with activation of multiple oncogenic tyrosine kinases. Interestingly, cancer cells with stable knockdown of endogenous LDH-A and rescue expression of a catalytic hypomorph LDH-A mutant, Y10F, demonstrate increased respiration through mitochondrial complex I to sustain glycolysis by providing NAD(+). However, such a compensatory increase in mitochondrial respiration in Y10F cells is insufficient to fully sustain glycolysis. Y10 rescue cells show decreased cell proliferation and ATP levels under hypoxia and reduced tumor growth in xenograft nude mice. Our findings suggest that tyrosine phosphorylation enhances LDH-A enzyme activity to promote the Warburg effect and tumor growth by regulating the NADH/NAD(+) redox homeostasis, representing an acute molecular mechanism underlying the enhanced lactate production in cancer cells.