Glioma cells with the IDH1 mutation modulate metabolic fractional flux through pyruvate carboxylase.
Glioma cells with the IDH1 mutation modulate metabolic fractional flux through pyruvate carboxylase.
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具有IDH1突变的胶质瘤细胞通过丙酮酸羧化酶调节代谢分数通量。
DOI：
10.1371/journal.pone.0108289
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发表时间：
2014
期刊：
影响因子：
3.7
通讯作者：
Ronen SM
中科院分区：
文献类型：
--
作者：
Izquierdo-Garcia JL;Cai LM;Chaumeil MM;Eriksson P;Robinson AE;Pieper RO;Phillips JJ;Ronen SM
超过70%的低级别胶质瘤在编码异柠檬酸脱氢酶1（IDH 1）的基因中携带杂合R132 H突变。这赋予酶将α-酮戊二酸转化为2-羟基戊二酸的新能力，最终导致肿瘤发生。2-羟基戊二酸产生的主要来源是谷氨酰胺，在癌症中，谷氨酰胺也是三羧酸循环（TCA）回补的来源。回补的另一个来源是通过丙酮酸羧化酶（PC）的丙酮酸通量，这是正常星形胶质细胞中的常见途径。本研究的目的是确定PC是否作为IDH 1突变细胞中TCA回补的来源，其中谷氨酰胺用于2-羟基戊二酸生产。研究了工程化以表达杂合突变IDH 1或野生型IDH 1的永生化正常人星形胶质细胞。丙酮酸通过PC和通过丙酮酸脱氢酶（PDH）的通量通过使用磁共振光谱探测[2- 13 C]葡萄糖衍生的13 C-标记的谷氨酸和谷氨酰胺的标记来确定。活性测定、RT-PCR和Western blotting检测相关酶的表达和活性。分析癌症基因组图谱（TCGA）数据以评估人类神经胶质瘤样品中酶的表达。与野生型细胞相比，突变IDH 1细胞显著增加通过PC的通量分数。这与PC活性和表达的显著增加有关。同时，PDH活性显著降低，可能是由PDH激酶3显著增加的抑制性PDH磷酸化介导的。与细胞中的观察结果一致，TCGA数据的分析表明与野生型IDH相比，表达突变IDH的人神经胶质瘤样品中PC表达显著增加。我们的研究结果表明，PC和PDH的变化可能是细胞适应IDH 1突变的重要组成部分，并可能作为潜在的治疗靶点。
Over 70% of low-grade gliomas carry a heterozygous R132H mutation in the gene coding for isocitrate dehydrogenase 1 (IDH1). This confers the enzyme with the novel ability to convert α-ketoglutarate to 2-hydroxyglutarate, ultimately leading to tumorigenesis. The major source of 2-hydroxyglutarate production is glutamine, which, in cancer, is also a source for tricarboxylic acid cycle (TCA) anaplerosis. An alternate source of anaplerosis is pyruvate flux via pyruvate carboxylase (PC), which is a common pathway in normal astrocytes. The goal of this study was to determine whether PC serves as a source of TCA anaplerosis in IDH1 mutant cells wherein glutamine is used for 2-hydroxyglutarate production. Immortalized normal human astrocytes engineered to express heterozygous mutant IDH1 or wild-type IDH1 were investigated. Flux of pyruvate via PC and via pyruvate dehydrogenase (PDH) was determined by using magnetic resonance spectroscopy to probe the labeling of [2-13C]glucose-derived 13C-labeled glutamate and glutamine. Activity assays, RT-PCR and western blotting were used to probe the expression and activity of relevant enzymes. The Cancer Genome Atlas (TCGA) data was analyzed to assess the expression of enzymes in human glioma samples. Compared to wild-type cells, mutant IDH1 cells significantly increased fractional flux through PC. This was associated with a significant increase in PC activity and expression. Concurrently, PDH activity significantly decreased, likely mediated by significantly increased inhibitory PDH phosphorylation by PDH kinase 3. Consistent with the observation in cells, analysis of TCGA data indicated a significant increase in PC expression in mutant IDH-expressing human glioma samples compared to wild-type IDH. Our findings suggest that changes in PC and PDH may be an important part of cellular adaptation to the IDH1 mutation and may serve as potential therapeutic targets.
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