MicroRNA-145靶向调控ABCG2表达在癫痫耐药中的作用

It is widely recognized that a variety of drug transporters are associated with drug resistance in epilepsy. As one of the ATP-binding cassette (ABC) transporters, studies about the role of ABCG2 (encoding breast cancer resistance protein) in drug-resistant epilepsy are few. Our published study has demonstrated that the polymorphisms of ABCG2 may affect lamotrigine metabolism in Chinese patients with epilepsy, and in vitro studies have indicated ABCG2 takes part in the transport of various anti-epileptic drugs (AEDs), affecting drug resistance in epilepsy. However, there were no immediate evidences about the correlation between ABCG2 and drug resistance, and mechanisms underlying the regulation of ABCG2 remain unclear. Previous studies have suggested miRNA-145 inhibits migration and invasion of glioma stem cells by targeting ABCG2. Moreover, our pre-experiment found that ABCG2 was overexpressed and miRNA-145 was low expressed in human epileptic brains. Thus, here was the hypothesis: the expression of miRNA-145 decreased in the epileptic brains, leading to the up-regulation of ABCG2 expression and low concentration of AEDs, then contributing to drug resistant in epilepsy. This study is aiming to identify the effects and mechanism of miRNA-145 on the expression of ABCG2 in drug-resistant epilepsy, to clarify the molecular mechanism of refractory epilepsy.

脑内多种药物转运蛋白过表达与癫痫耐药密切相关。ABCG2转运蛋白作为血脑屏障中ATP结合盒转运蛋白的一种，在癫痫耐药方面的研究尚不多见。申请者前期研究发现ABCG2基因多态性与癫痫患者拉莫三嗪血药浓度相关，离体实验也证实ABCG2参与脑内多种抗癫痫药物转运，但目前尚没有ABCG2参与癫痫耐药的直接证据，其调控机制也不清楚。动物和人脑研究均提示癫痫脑内ABCG2表达增加，近来研究发现miRNA-145能负性调控胶质瘤干细胞ABCG2表达，我们的预实验在难治性癫痫脑标本中检测到ABCG2 mRNA水平增加，miRNA-145表达减少。因此，我们提出假设：癫痫患者脑内miRNA-145表达减少，负性调控血脑屏障ABCG2表达，影响抗癫痫药物在脑内的转运，从而导致癫痫耐药。本研究拟采用整体和离体模型，阐明miRNA-145靶向调控脑内ABCG2表达在癫痫耐药中的作用，揭示癫痫耐药的分子学机制。

癫痫是一组脑部神经元异常放电所导致，以发作性、短暂性、重复性和刻板性的中枢神经系统功能失常为特征的慢性综合征。尽管新型抗癫痫药物在疗效和耐受性方面已取得显著进步，但仍有近三分之一的癫痫患者最终会发展为难治性癫痫。多药转运体的表达上调与药物难治性癫痫的发生密切相关。ABCG2转运蛋白作为血脑屏障中多药转运体蛋白的一种，在癫痫耐药方面的研究尚不多见。基于前期研究和文献，本项目拟阐明微小RNA-145（miRNA-145）调控ABCG2的表达参与癫痫耐药的作用机制。首先，我们利用癫痫患者脑标本和动物模型明确miRNA-145在脑内表达显著降低，伴随ABCG2表达上调。为了进一步明确miRNA-145是否靶向调控癫痫患者血脑屏障中ABCG2的表达，我们利用人脑血管内皮细胞干预miRNA-145的表达，结果发现miRNA-145并不影响ABCG2mRNA和蛋白的表达，推测两者的表达差异可能仅是伴随关系；与此同时，我们发现多药转运体ABCB1mRNA出现显著性改变。此外，血清miRNA常被认为是某些中枢神经系统疾病的生物学标志物，我们的研究发现miRNA-145在难治性癫痫患者血清中的表达水平明显降低，对于识别难治性癫痫具有良好的敏感性和特异性，且癫痫发病年龄早、发作频率高或既往存在中枢神经系统损伤史的患者血清中miRNA-145的表达水平更低。综上所述，我们推测miRNA-145与癫痫的发生发展具有密切关系，还可能通过调控ABCB1表达参与癫痫耐药，上述研究为进一步探索 miRNA在癫痫发病中的机制打下了重要基础。