P-GLYCOPROTEIN MEDIATED CHEMORESISTANCE IN ALS THERAPY

描述（由申请人提供）：高表达水平、多特异性和高转运效力使p -糖蛋白成为脑和血脑屏障的选择性看门人，从而成为药物在中枢神经系统中传递的主要障碍。因此，p -糖蛋白限制了大量药物和外源药物进入中枢神经系统，导致中枢神经系统候选药物成功率低，并可能导致患者对中枢神经系统药物治疗的反应存在差异。因此，调节p糖蛋白可以改善药物进入中枢神经系统和药物治疗。在这里，我们建议在ALS治疗的背景下验证这一概念。通过遗传学和药理学两方面的方法来消除P-gp的作用，我们将评估去甲二氢愈创木酸（NDGA）对SOD1-G93A转基因ALS小鼠模型的治疗效果。在基于细胞的ALS筛查中，我们发现NDGA是一种有效的特异性谷氨酸转运活性增强剂；在SOD1-G93A小鼠中进行的临床试验表明，其潜在的治疗效果可能受到疾病驱动的脊髓P-gp转运蛋白上调的阻碍。为了进一步评估NDGA作为候选治疗药物，我们在Aim 1中提出，确定遗传去除P-糖蛋白介导的耐药是否会恢复NDGA介导的谷氨酸摄取增强作用和ALS小鼠模型的治疗效果。在Aim 2中，我们将确定NDGA和埃拉西达（一种有效的选择性P-gp抑制剂）联合治疗ALS小鼠是否会对小鼠有益。如果成功，这些方法不仅将确定增加ALS小鼠谷氨酸清除率对ALS表型的真正影响，而且还将为重新考虑在SOD1-G93A小鼠ALS模型中尝试的许多不成功的临床试验提供依据，其中多药物转运蛋白的功能可能会损害可能的阳性结果。

DESCRIPTION (provided by applicant): High expression levels, multispecificity, and high transport potency makes the P-glycoprotein a selective gatekeeper of the brain and blood-brain barrier and thus a primary obstacle to drug delivery in the CNS. As such, P-glycoprotein limits CNS entry of a large number of drugs and xenobiotics, contributes to the poor success rate of CNS drug candidates, and probably contributes to patient-to-patient variability in response to CNS pharmacotherapy. Modulating P-glycoprotein could therefore improve drug delivery into the CNS and drug therapy. Here, we propose to validate this concept in the context of ALS therapy. By following both genetic and pharmacologic approaches to obliterate the action of P-gp we will evaluate the therapeutic efficacy of nordihydroguaiaretic acid (NDGA) to the SOD1-G93A transgenic mouse model of ALS. We identified NDGA as a potent and specific glutamate transport activity enhancer in a cell-based screen for ALS; clinical testing in the SOD1-G93A mice indicated that its potential therapeutic efficacy could have been hampered by a disease-driven upregulation of P-gp transporters in the spinal cord. To further evaluate NDGA as candidate therapeutic we propose in Aim 1 to determine if genetic removal of P- glycoprotein-mediated pharmacoresistance will rescue NDGA-mediated glutamate uptake enhancing effect and therapeutic efficacy in a mouse model of ALS. In Aim 2 we will determine if co-treatment of the ALS mice with NDGA and elacridar, a potent and selective inhibitor of P-gp, will therapeutically benefit the mice. If successful, these approaches not only will determine the true impact on the ALS phenotype of increasing glutamate clearance in ALS mice, but will also provide the rationale to reconsider many unsuccessful clinical trials that have been attempted in the SOD1-G93A mouse model of ALS in which the function of multidrug transporter proteins could have compromised a possible positive outcome. PUBLIC HEALTH RELEVANCE: Amyotrophic lateral sclerosis (ALS) is one of the most devastating and lethal progressive neuromuscular disorders. Over 30,000 people are living with ALS in the United States and approximately 5,000 Americans will be diagnosed with ALS this year. P-glycoprotein limits the entry into the brain and spinal cord for a large number of drugs and contributes to the poor success rate of drug candidates. Modulating P-glycoprotein could therefore improve drug delivery into the brain and spinal cord. Here, we propose to validate this concept in the context of ALS therapy. By following both genetic and pharmacologic approaches to obliterate the action of P-glycoprotein we will evaluate the therapeutic value of a potent glutamate transport enhancer drug, NDGA, to mice model of ALS. If successful, this approach not only will determine the true therapeutic impact of increasing glutamate clearance in ALS mice, but also will open new therapeutic venues for ALS and provide the rationale to reconsider many unsuccessful clinical trials that have been attempted in mice models of ALS in which the function of P-gp could have hampered a possible positive outcome.