BackgroundMetabolism gained increasing interest for the understanding of diseases and to pinpoint therapeutic intervention points. However, classical metabolomics techniques only provide a very static view on metabolism. Metabolic flux analysis methods, on the other hand, are highly targeted and require detailed knowledge on metabolism beforehand.ResultsWe present a novel workflow to analyze non-targeted metabolome-wide stable isotope labeling data to detect metabolic flux changes in a non-targeted manner. Furthermore, we show how similarity-analysis of isotopic enrichment patterns can be used for pathway contextualization of unidentified compounds. We illustrate our approach with the analysis of changes in cellular metabolism of human adenocarcinoma cells in response to decreased oxygen availability. Starting without a priori knowledge, we detect metabolic flux changes, leading to an increased glutamine contribution to acetyl-CoA production, reveal biosynthesis of N-acetylaspartate by N-acetyltransferase 8-like (NAT8L) in lung cancer cells and show that NAT8L silencing inhibits proliferation of A549, JHH-4, PH5CH8, and BEAS-2B cells.ConclusionsDifferential stable isotope labeling analysis provides qualitative metabolic flux information in a non-targeted manner. Furthermore, similarity analysis of enrichment patterns provides information on metabolically closely related compounds. N-acetylaspartate and NAT8L are important players in cancer cell metabolism, a context in which they have not received much attention yet.

中文翻译：

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弥合非靶向稳定同位素标记和代谢通量分析之间的差距


背景代谢对于了解疾病和确定治疗干预点越来越感兴趣。然而，经典的代谢组学技术仅提供代谢的非常静态的视图。另一方面，代谢通量分析方法具有很强的针对性，需要事先对代谢有详细的了解。结果我们提出了一种新颖的工作流程来分析非靶向代谢组范围的稳定同位素标记数据，以非靶向方式检测代谢通量变化。此外，我们展示了如何使用同位素富集模式的相似性分析来对未识别化合物进行途径背景化。我们通过分析人类腺癌细胞响应氧气可用性降低的细胞代谢变化来说明我们的方法。在没有先验知识的情况下，我们检测到代谢通量的变化，导致谷氨酰胺对乙酰辅酶A产生的贡献增加，揭示了肺癌细胞中 N-乙酰转移酶 8 样 (NAT8L) 的 N-乙酰天冬氨酸生物合成，并表明 NAT8L 沉默抑制A549、JHH-4、PH5CH8 和 BEAS-2B 细胞的增殖。结论差异稳定同位素标记分析以非靶向方式提供定性代谢流信息。此外，富集模式的相似性分析提供了代谢密切相关的化合物的信息。 N-乙酰天冬氨酸和 NAT8L 是癌细胞代谢的重要参与者，但它们尚未受到太多关注。