Anticancer compound 3-bromopyruvate (3-BrPA) suppresses cancer cell growth via targeting glycolytic and mitochondrial metabolism. The malignant peripheral nerve sheath tumor (MPNST), a very aggressive, therapy resistant, and Neurofibromatosis type 1 associated neoplasia, shows a high metabolic activity and affected patients may therefore benefit from 3-BrPA treatment. To elucidate the specific mode of action, we used a controlled cell model overexpressing proteasome activator (PA) 28, subsequently leading to p53 inactivation and oncogenic transformation and therefore reproducing an important pathway in MPNST and overall tumor pathogenesis. Viability of MPNST cell lines S462, NSF1, and T265 in response to increasing doses (0–120 μM) of 3-BrPA was analyzed by CellTiter-Blue® assay. Additionally, we investigated viability, reactive oxygen species (ROS) production (dihydroethidium assay), nicotinamide adenine dinucleotide dehydrogenase activity (NADH-TR assay) and lactate production (lactate assay) in mouse B8 fibroblasts overexpressing PA28 in response to 3-BrPA application. For all experiments normal and nutrient deficient conditions were tested. MPNST cell lines were furthermore characterized immunohistochemically for Ki67, p53, bcl2, bcl6, cyclin D1, and p21. MPNST significantly responded dose dependent to 3-BrPA application, whereby S462 cells were most responsive. Human control cells showed a reduced sensitivity. In PA28 overexpressing cancer cell model 3-BrPA application harmed mitochondrial NADH dehydrogenase activity mildly and significantly failed to inhibit lactate production. PA28 overexpression was associated with a functional glycolysis as well as a partial resistance to stress provoked by nutrient deprivation. 3-BrPA treatment was not associated with an increase of ROS. Starvation sensitized MPNST to treatment. Aggressive MPNST cells are sensitive to 3-BrPA therapy in-vitro with and without starvation. In a PA28 overexpression cancer cell model leading to p53 inactivation, thereby reflecting a key molecular feature in human NF1 associated MPNST, known functions of 3-BrPA to block mitochondrial activity and glycolysis were reproduced, however oncogenic cells displayed a partial resistance. To conclude, 3-BrPA was sufficient to reduce NF1 associated MPNST viability potentially due inhibition of glycolysis which should lead to the initiation of further studies and promises a potential benefit for NF1 patients.

中文翻译：

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在代表性的体外模型中，抗癌剂3-溴丙酮酸降低了MPNST的生长并抑制了代谢途径。

抗癌化合物3-溴丙酮酸（3-BrPA）通过靶向糖酵解和线粒体代谢来抑制癌细胞的生长。恶性周围神经鞘瘤（MPNST）是一种非常具有侵略性，抗药性的，与1型神经纤维瘤病相关的肿瘤，显示出高代谢活性，因此患病的患者可能会受益于3-BrPA治疗。为了阐明特定的作用方式，我们使用了过表达蛋白酶体激活剂（PA）28的受控细胞模型，随后导致p53失活和致癌转化，因此在MPNST和总体肿瘤发病机理中重现了重要的途径。通过CellTiter-Blue®分析法分析了MPNST细胞系S462，NSF1和T265对3-BrPA剂量增加（0-120μM）的活力。此外，我们调查了生存能力，响应3-BrPA施用而过量表达PA28的小鼠B8成纤维细胞中活性氧（ROS）的产生（二氢乙啶测定），烟酰胺腺嘌呤二核苷酸脱氢酶活性（NADH-TR测定）和乳酸产生（乳酸测定）。对于所有实验，均测试了正常和营养缺乏的条件。此外，针对Ki67，p53，bcl2，bcl6，细胞周期蛋白D1和p21免疫组化地表征了MPNST细胞系。MPNST显着响应剂量依赖于3-BrPA的应用，其中S462细胞响应最强。人类对照细胞显示出降低的敏感性。在PA28过表达的癌细胞模型3-BrPA中，轻度损伤线粒体NADH脱氢酶的活性，并且明显不能抑制乳酸的产生。PA28的过表达与功能性糖酵解以及营养物缺乏引起的部分胁迫抗性有关。3-BrPA治疗与ROS升高无关。饥饿使MPNST对治疗敏感。在有或没有饥饿的情况下，侵略性MPNST细胞对3-BrPA体外治疗敏感。在导致p53失活从而反映人类NF1相关MPNST关键分子特征的PA28过表达癌细胞模型中，再现了3-BrPA阻断线粒体活性和糖酵解的已知功能，但是致癌细胞显示出部分耐药性。总而言之，3-BrPA足以降低可能由于抑制糖酵解而导致的与NF1相关的MPNST生存力，这应导致进一步研究的开始，并有望为NF1患者带来潜在的益处。