Liu Yang, Gu Yajun, Ng Serina, Deng Zaian, Lyon Christopher J, Koay Eugene J, Ning Bo, Katz Matthew H, Chiao Paul J, Fan Jia, Han Haiyong, Von Hoff Daniel, Hu Tony Y
Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, LA 70112, USA.
Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX 77030, USA.
Sci Bull (Beijing). 2020 Sep 30;65(18):1570-1579. doi: 10.1016/j.scib.2020.04.023. Epub 2020 Apr 18.
The critical roles of oxygen homeostasis in metabolism are indisputable and hypoxic responses are correlated with the pathogenesis of gastrointestinal, pulmonary, renal diseases and cancers. Evaluating tissue hypoxia to predict treatment outcome is challenging, however, due to the lack of rapid, accurate and non-invasive methods. Hypoxia enhances prolyl-4-hydroxylase α1 (P4HA1) expression, which can convert bradykinin (BK) to hydroxyprolyl-BK (Hyp-BK), leading us to hypothesize that circulating Hyp-BK/BK ratios may reflect tissue hypoxia and predict treatment outcomes. Direct quantification of Hyp-BK peptides in serum or plasma by conventional MALDI-TOF MS analysis is technically challenging. In our study, a nanopore-based fractionation and enrichment protocol was utilized to allow the simple workflow for circulating Hyp-BK/BK analysis. Hypoxia is linked to poor prognosis due to its role in promoting pancreatic cancer progression and metastasis. Here we show that P4HA1 expression was increased in pancreatic tumors versus adjacent tissue, associated with poor survival, and corresponded with tumor expression of the hypoxia inducible factor 1α (HIF-1α) and carbonic anhydrase 9 (CA9). Hypoxia-induced P4HA1 expression and BK conversion to Hyp-BK were found to be HIF-1α dependent, pre-treatment serum Hyp-BK/BK ratios corresponded with tissue HIF-1α and P4HA1 expression, and high Hyp-BK/BK levels corresponded with poor response to therapy. These results suggest that pre-treatment circulating Hyp-BK/BK ratios may have value as a non-invasive, surrogate indicator of tissue hypoxia and tumor responses to therapy.
氧稳态在新陈代谢中的关键作用是无可争议的，缺氧反应与胃肠道、肺部、肾脏疾病及癌症的发病机制相关。然而，由于缺乏快速、准确且无创的方法，评估组织缺氧以预测治疗结果具有挑战性。缺氧会增强脯氨酰-4-羟化酶α1（P4HA1）的表达，该酶可将缓激肽（BK）转化为羟脯氨酰-缓激肽（Hyp-BK），这使我们推测循环中的Hyp-BK/BK比值可能反映组织缺氧情况并预测治疗结果。通过传统的基质辅助激光解吸电离飞行时间质谱（MALDI-TOF MS）分析直接定量血清或血浆中的Hyp-BK肽在技术上具有挑战性。在我们的研究中，采用了基于纳米孔的分级分离和富集方案，以实现循环Hyp-BK/BK分析的简单工作流程。缺氧因其在促进胰腺癌进展和转移中的作用而与不良预后相关。在此我们表明，与相邻组织相比，胰腺癌组织中P4HA1表达增加，与生存率低相关，且与缺氧诱导因子1α（HIF-1α）和碳酸酐酶9（CA9）的肿瘤表达相对应。发现缺氧诱导的P4HA1表达以及BK向Hyp-BK的转化依赖于HIF-1α，治疗前血清Hyp-BK/BK比值与组织HIF-1α和P4HA1表达相对应，且高Hyp-BK/BK水平与治疗反应差相对应。这些结果表明，治疗前循环中的Hyp-BK/BK比值可能作为组织缺氧和肿瘤对治疗反应的无创替代指标具有价值。
