MRP2及其遗传变异在顺铂肾蓄积及肾毒性中的作用

Cisplatin is one of the most widely used anticancer agents for the treatment of solid tumors. The clinical use of cisplatin has always been hampered by its nephrotoxicity. This serious side-effect often delays or even stops subsequent chemotherapy cycles, thereby reducing overall anticancer efficacy. Multidrug resistance protein 2 (MRP2) is one of the most important efflux transporters, its function in kidney and the association with cisplatin nephrotoxicity has not been intensively identified yet. Previous studies indicated that mice treated with the inductor of Mrp2 demostrated a decreased susceptibility to cisplatin nephrotoxicity. In addition, MRP2 expression level in kidney was increased in cisplatin-treated wild-type mice, which was likely to be a compensatory mechanism to enhance the clearance of toxic compound. Therefore, we hypothesize that Mrp2 plays a critical role in the clearance of cisplatin in kidney, which effeciently prevents from its accumulation and nephrotoxicity. And the genetic polymorphisms of MRP2 may influence the extent of cisplatin nephrotoxicity in cancer patients. In this project, firstly we will determine the role of Mrp2 in transport of cisplatin in vitro, using several technologies, including over-expression system, site-directed mutagenesis, and RNA interference. Secondly, we will perform pharmacokinetics and toxicology of cisplatin in the MRP2 knockout mice model to confirm the key role of MRP2 in cisplatin clearance in vivo. Finally, we will exert some drug clinical trial in cancer patients. Our study will reveal a new and major factor that contributes to new preventive and therapeutic approaches to cisplatin nephrotoxicity. It is of great importance to develop a new targeted therapy based on drug transporter to ensure drug safety, benefit future therapeutic interventions and improve the survival of cancer patients.

顺铂是一种有效的抗实体肿瘤化疗药物，其使用因肾毒性而受到限制。顺铂引起的肾毒性使后续化疗周期延迟，因而影响顺铂化疗的整体效应。多药耐药相关蛋白2（MRP2）是一种重要的外排型转运体，其在肾脏的功能及与顺铂肾毒性的关系尚未研究清楚。初步研究发现，应用Mrp2诱导剂可使小鼠的顺铂肾损伤程度减轻。而顺铂处理的野生型小鼠肾脏Mrp2表达增加，推测可能是加快顺铂清除的一种代偿机制。因此我们认为MRP2是参与顺铂肾脏排泄的主要转运体，对顺铂的肾蓄积和肾毒性起重要作用。并假设MRP2的遗传变异可影响顺铂肾损伤的程度。本项目将应用超表达、定点突变和RNA干扰细胞模型，Mrp2(-/-)基因敲除小鼠模型及肿瘤病人药物临床试验多层面验证MRP2在顺铂的肾蓄积及肾毒性中的作用。有助于完善以转运体等多分子为靶点设计新的预防和治疗手段，对于提高化疗药物安全性、帮助医生优化化疗方案和改善肿瘤患者生存预后具有重要意义。

顺铂是一种无机金属化疗药，广泛用于头颈部肿瘤、肺癌、睾丸癌、卵巢癌、膀胱癌等实体瘤的治疗。虽然顺铂的疗效确切，但却容易引起听力毒性、胃肠道反应、血液毒性、急性肾损伤以及慢性肾功能下降等毒副反应。目前，研究认为顺铂的肾毒性与顺铂在近端肾小管中的蓄积密切相关，而顺铂相关转运体MRP2, OCT1,OCT2,MATE1及MATE2k在顺铂转运过程中发挥着重要作用。本研究发现昂丹司琼和替米沙坦是MATEs转运体的抑制剂，体外细胞模型中可抑制MATEs对二甲双胍的转运。在小鼠顺铂肾毒性模型的研究发现，昂丹司琼和替米沙坦可以增加顺铂在肾脏的蓄积以及顺铂引起的肾脏毒性。此外昂丹司琼还可以改变二甲双胍在小鼠体内的药代动力学及肝肾的药物蓄积。质子泵抑制剂（PPIs）是较强的OCT2转运体的抑制剂，PPIs的使用可以降低顺铂在肾脏的摄入降低顺铂引起的肾脏毒性。在健康受试者体内的研究发现，雷贝拉唑可以增加OCT2底物药二甲双胍的血药浓度。本研究通过回顾性分析铂类化疗后患者肾功能数据的变化和小鼠年龄模型的研究，发现年龄是顺铂引起的肾毒性发生的独立危险因素。顺铂在老年小鼠肾脏蓄积的增加，与顺铂相关转运体表达水平有关。抗氧化信号通路活性的降低以及炎症反应水平的升高也是顺铂肾毒性在老年小鼠中更加明显的原因。本项目研究还构建LRP6基因敲除小鼠模型，与野生型小鼠相比，LRP6突变型小鼠顺铂所致急性肾损伤更加显著，研究提示LRP6-WNTs-β-catenin信号通路对顺铂肾毒性具有保护作用。