Department of Neurosurgery, University Hospital Schleswig Holstein, Campus Kiel, Kiel, Germany.
J Neurooncol. 2012 Jul;108(3):443-50. doi: 10.1007/s11060-012-0857-9. Epub 2012 Apr 15.
Epileptic seizures are among the presenting clinical signs of malignant glioma patients, frequently necessitating treatment with antiepileptic drugs (AEDs). The efficacy of 5-aminolevulinic acid (5-ALA)-based intraoperative fluorescence-guided surgery and photodynamic therapy (PDT) in glioblastoma multiforme (GBM) patients depends on the specific accumulation and total amount of intracellularly synthesized protoporphyrin IX (PpIX) in tumour cells. In this study, we investigated the effect of the AEDs phenytoin (PHY) and levetiracetam (LEVE) on 5-ALA-induced PpIX accumulation in two glioma cell lines (U373 MG and U-87 MG) and primary GBM cells isolated from a human biopsy. After treatment with PHY and LEVE for three days cells were incubated with 1 mM: 5-ALA for 4 h and PpIX accumulation was determined by fluorescence measurement. We observed a decrease in PpIX synthesis of up to 55 ± 12 % in primary GBM cells after incubation with phenytoin. This reduction was dose-dependent for all tested cell lines and primary GBM cells. LEVE on the other hand did not alter PpIX concentration in GBM cells. PDT was performed in vitro by irradiating the GBM cells with light doses from 0.5 to 10 J cm(-2) at 627 nm after AED and 5-ALA treatment. Although less PpIX accumulated in PHY-treated cells, efficacy of PDT was not affected. We assume that damage to the mitochondrial membrane by PHY inhibits PpIX synthesis in vitro, because we showed mitochondrial dysfunction as a result of reduced mitochondrial membrane potential in PHY-treated cells. No change in glutathione status was observed. To evaluate further the effect of PHY on PpIX fluorescence, and to establish its significance in clinical practice, animal and clinical studies are required, because the results presented here imply PHY may reduce intracellular accumulation of PpIX in patients with high-grade gliomas.
癫痫发作是恶性神经胶质瘤患者的临床表现之一，常需要使用抗癫痫药物（AEDs）进行治疗。5-氨基酮戊酸（5-ALA）为基础的术中荧光引导手术和光动力疗法（PDT）在多形性胶质母细胞瘤（GBM）患者中的疗效取决于肿瘤细胞内合成的原卟啉 IX（PpIX）的特异性积累和总量。在这项研究中，我们研究了抗癫痫药物苯妥英（PHY）和左乙拉西坦（LEVE）对两种神经胶质瘤细胞系（U373 MG 和 U-87 MG）和从人类活检中分离的原发性 GBM 细胞中 5-ALA 诱导的 PpIX 积累的影响。用 PHY 和 LEVE 处理三天后，将细胞用 1mM：5-ALA 孵育 4 小时，通过荧光测量测定 PpIX 积累。我们观察到在用苯妥英孵育后，原发性 GBM 细胞中的 PpIX 合成减少了高达 55±12%。这种减少对于所有测试的细胞系和原发性 GBM 细胞都是剂量依赖性的。另一方面，LEVE 不会改变 GBM 细胞中的 PpIX 浓度。在用 AED 和 5-ALA 处理后，通过用 627nm 波长的光照射从 0.5 到 10J/cm2 的剂量在体外进行 PDT。尽管在 PHY 处理的细胞中积累的 PpIX 较少，但 PDT 的疗效不受影响。我们假设 PHY 通过抑制线粒体膜的功能而损害线粒体膜，因为我们显示 PHY 处理的细胞中线粒体膜电位降低导致线粒体功能障碍。未观察到谷胱甘肽状态的变化。为了进一步评估 PHY 对 PpIX 荧光的影响，并确定其在临床实践中的意义，需要进行动物和临床研究，因为这里提出的结果表明 PHY 可能会降低高级别神经胶质瘤患者体内 PpIX 的细胞内积累。
