2-hydroxyglutarate (2-HG) has gained considerable importance in glioma and blood cancers that have mutations in the IDH1/2 gene. In the current study we show for the first time that pancreatic tumors produce 2HG in the absence of IDH1/2 mutation. Our study shows that hypoxic pancreatic tumors that have activated lactate dehydrogenase (LDH) activity, produce the L-isoform of 2HG. Metabolic mass spectrometric analysis along with chiral derivatization showed that pancreatic cancer cells as well as stromal cells secrete the L- isomeric form of 2-hydroxyglutarate (L-2HG) when exposed to hypoxic environment. Serum analysis of human pancreatic cancer patients also showed similar accumulation of L-2HG. Our results showed that this abnormally accumulated L-2HG regulates self-renewal by increasing expression of genes associated with stemness (Sox-2, CD133) and by decreasing expression of differentiation genes (Pdx-1, HB9, NKX6.1). Further analysis showed that secreted L-2HG mediates cross talk with immune T-cells and hampers their proliferation and migration thereby suppressing the anti-tumor immunity. In vivo targeting of LDH enzyme with inhibitor (GSK2837808A) showed decrease in L-2HG as well as subsequent tumor regression and sensitization to immune-checkpoint therapy. Present study shows for the first time that hypoxia mediated accumulation of L-2HG drives self-renewal in pancreatic cancer by shifting critical balance of gene expression towards stemness and promotes immune suppression by impairing T cell activation in this disease. Additionally, it indicates that targeting LDH can sensitize pancreatic tumors to anti-PD1 therapy by decreasing L-2HG and reverting their immune evasive function.

中文翻译：

---

低氧驱动的彗星代谢物L-2HG维持“干”分化平衡并促进胰腺癌的免疫抑制

2-羟基戊二酸（2-HG）在神经胶质瘤和IDH1 / 2基因突变的血液癌中具有重要意义。在本研究中，我们首次显示在没有IDH1 / 2突变的情况下胰腺肿瘤会产生2HG。我们的研究表明，具有激活的乳酸脱氢酶（LDH）活性的低氧胰腺肿瘤会产生2HG的L型。代谢质谱分析和手性衍生反应表明，胰腺癌细胞以及基质细胞暴露于低氧环境时会分泌L-异构体形式的2-羟基戊二酸（L-2HG）。对人胰腺癌患者的血清分析也显示了相似的L-2HG积累。我们的结果表明，这种异常积累的L-2HG通过增加与茎相关的基因的表达来调节自我更新（Sox-2，CD133），并降低分化基因（Pdx-1，HB9，NKX6.1）的表达。进一步的分析表明，分泌的L-2HG介导了与免疫T细胞的串扰，阻碍了它们的增殖和迁移，从而抑制了抗肿瘤免疫力。用抑制剂（LDKSK2837808A）对LDH酶的体内靶向显示L-2HG降低以及随后的肿瘤消退和对免疫检查点疗法的敏感性。目前的研究首次表明，低氧介导的L-2HG积累通过将基因表达的关键平衡移向干性来驱动胰腺癌的自我更新，并通过损害该疾病中的T细胞活化来促进免疫抑制。另外，