Mosyagin Igor, Runge Uwe, Schroeder Henry W, Dazert Eike, Vogelgesang Silke, Siegmund Werner, Warzok Rolf W, Cascorbi Ingolf
Institute of Pharmacology, University Hospital Schleswig-Holstein, Kiel, Germany.
Epilepsia. 2008 Sep;49(9):1555-61. doi: 10.1111/j.1528-1167.2008.01661.x. Epub 2008 May 20.
There is evidence from studies in rodents that P-glycoprotein (P-gp) overexpression is implicated in the causation of refractory epilepsy. Genetic variants in the human ABCB1 (MDR1) gene were shown to affect the expression levels of the transporter in various tissues and to be associated with refractory epilepsy. However, the effect of the genetic variants on the P-gp level in epileptogenic brain tissue is poorly investigated. In the present study, we examined the impact of putatively functional polymorphisms 3435C>T and 2677G>T in the ABCB1 gene on the ABCB1 mRNA expression and P-gp content in human brain tissue from epileptogenic foci of the patients with refractory epilepsy.
Fresh brain tissue specimens were obtained from therapy-refractory epilepsy patients during neurosurgery of the epileptogenic focus. We determined the ABCB1 mRNA expression in 23 samples using 5' exonuclease-based real-time polymerase chain reaction (PCR) as well as the P-gp content in 32 samples determined by immunohistochemistry, genotyping was performed by PCR/restriction fragment length polymorphism (RFLP).
There was lack of association of 3435C>T and 2677G>T as well as diplotype configurations on ABCB1 mRNA expression and P-gp content in epileptogenic brain tissues.
We cannot exclude an association of ABCB1 variants on P-gp function, but our results suggest that brain ABCB1 mRNA and protein expression is not substantially influenced by major ABCB1 genetic variants thus explaining in part results from case-control studies obtaining lack of association of ABCB1 polymorphisms to the risk of refractory epilepsy.
啮齿动物研究中有证据表明，P-糖蛋白（P-gp）过表达与难治性癫痫的病因有关。人类ABCB1（MDR1）基因的遗传变异被证明会影响该转运蛋白在各种组织中的表达水平，并与难治性癫痫相关。然而，遗传变异对致痫脑组织中P-gp水平的影响研究较少。在本研究中，我们检测了ABCB1基因中可能具有功能的多态性3435C>T和2677G>T对难治性癫痫患者致痫灶人脑组织中ABCB1 mRNA表达和P-gp含量的影响。
在难治性癫痫患者致痫灶的神经外科手术中获取新鲜脑组织标本。我们使用基于5'外切核酸酶的实时聚合酶链反应（PCR）测定了23个样本中的ABCB1 mRNA表达，并通过免疫组织化学测定了32个样本中的P-gp含量，通过PCR/限制性片段长度多态性（RFLP）进行基因分型。
3435C>T和2677G>T以及双倍型组合与致痫脑组织中ABCB1 mRNA表达和P-gp含量缺乏关联。
我们不能排除ABCB1变异与P-gp功能的关联，但我们的结果表明，大脑ABCB1 mRNA和蛋白质表达并未受到ABCB1主要遗传变异的实质性影响，这在一定程度上解释了病例对照研究中ABCB1多态性与难治性癫痫风险缺乏关联的结果。
