人单核细胞白血病细胞系SHI-1的多药耐药和耐药蛋白的表达

目的 探讨人单核细胞白血病细胞系SHI-1多药耐药谱及其机制.方法 噻唑蓝(MTT)检测SHI-1细胞对柔红霉素、鬼臼乙叉甙、高三尖杉酯碱、紫杉醇和长春新碱的敏感性;流式细胞术(FCM)检测SHI-1细胞中P糖蛋白(P-gp)、多药耐药相关蛋白(MRP)、肺耐药相关蛋白(LRP)、乳腺癌耐药蛋白(BCRP)、谷胱甘肽-S-转移酶-π(GST-π)等耐药蛋白的表达.结果 MTT药敏实验结果显示SHI-1细胞存在着多药耐药,尤其对VP-16最为明显.FCM检测显示SHI-1细胞中P-gp阳性比例10.78%,相对荧光强度(RFI)为1.02;GST-π阳性率93.52%,RFI 6.91;LRP阳性率92.86%,RFI 8.00;MRP阳性率4.54%,RFI 1.38;BCRP阳性率3.84%,RFI 1.06.结论 SHI-1细胞存在多药耐药,以对VP-16最为明显,其耐药机制可能与LRP和GST-π的高表达有关.     

贲门癌组织中多药耐药基因和多药耐药相关蛋白基因表达的临床研究

目的 了解多药耐药基因(MDR1)和多药耐药相关蛋白基因(MRP)在贲门癌组织中的表达及其临床意义。方法 采用逆转录-多聚酶链反应(RT-PCR)。观察46侧贲门癌及癌旁组织中MDR1和MRP的表达。结果 癌组织中MDR1和MRP表达的阳性率分别为63%和50%,均高于癌旁组织(P<0.05);贲门癌术前化疗者MDR1 mRNA和MRP mRNA表达水平显著高于未化疗者(P<0.05);中低分化肿瘤MDR1和MRP两基因mRNA表达水平高于高分化肿瘤(P<0.05)。结论 贲门癌组织中具有内源和获得性耐药性;MDR1和MRP表达与肿瘤的TNM分期无关,其高表达状态可预示肿瘤组织的分化不良。     

以膜转运蛋白为靶点的胃癌多药耐药研究进展

胃癌是我国病死率最高的常见恶性肿瘤,肿瘤多药耐药（MDR）严重影响临床化疗的效果,而膜转运蛋白如P－糖蛋白（P－gp）、MDR相关蛋白（MRP）、乳腺癌耐药蛋白(BCRP)和肺耐药相关蛋白(LRP)的异常表达是引起肿瘤多药耐药的重要机制之一. 简述上述4种膜转运蛋白在胃癌中的异常表达、耐药机制、临床意义及其逆转药.     

雷公藤多甙片对狼疮性肾炎外周血单个核细胞多药耐药蛋白表达的影响

目的研究雷公藤多甙片(TG)对狼疮性肾炎外周血单个核细胞(PBMCs)多药耐药蛋白表达的影响。方法选择2015年11月~2017年5月我院收治的58例LN患者为研究对象,分为接受TG治疗的TG组(29例)和接受常规激素治疗的对照组(29例),分别提取两组治疗前后PBMCs,采用反转录-聚合酶链反应(RT-PCR)法检测TG对PBMCs多药耐药相关蛋白蛋白(MRP)和多药耐药相关基因(MDR1)和P-糖蛋白170(P-gp 170)表达的影响。结果治疗3个月后,两组PBMCs MRP、MDR1 m RNA相对表达量均明显提高(P0.05),且TG组PBMCs MRP、MDR1 m RNA相对表达量显著高于对照组(P0.05);两组PBMCs P-gp 170阳性表达率均明显提高(P0.05),且TG组PBMCs P-gp 170阳性表达率显著高于对照组(P0.05)。结论 TG可有效提高LN患者PBMCs MRP、MDR1及P-gp 170表达,提高患者免疫力,改善预后,LN患者治疗中应检测多药耐药蛋白表达水平以确定其耐药性。     

上皮性卵巢癌中耐药相关基因的表达及临床意义

目的 通过测定多药耐药基因( MDR1)、多药耐药相关蛋白(MRP)和肺耐药相关蛋白(LRP)在上皮性卵巢癌中的表达,了解其在上皮性卵巢癌化疗耐药中的作用.方法 采用逆转录-聚合酶链反应( RT-PCR)测定42例上皮性卵巢癌、40例良性卵巢肿瘤和30例正常卵巢组织中上述3项指标的表达,分析其临床分期、病理特征、化疗疗效等的关系.结果 ①在正常卵巢、良性卵巢肿瘤和卵巢癌组织中,MDR1 的阳性表达分别为:0％、0％、30.95％; MRP阳性表达率分别为:13.3％、12.5％、66.7％; LRP阳性表达率分别为:26.7％、52.5％、83.3％.卵巢癌组织中上述3项指标均明显高于正常卵巢和良性卵巢肿瘤,差异有显著性(P＜0.05),而正常卵巢和良性卵巢肿瘤比较,差异无显著性(P＞0.05).②MDR1和MRP在Ⅲ～Ⅳ期的阳性表达率明显高于Ⅰ～Ⅱ期,LRP在Ⅰ～Ⅱ期和Ⅲ～Ⅳ期的阳性表达率无明显差异.③浆液囊腺癌的MDR1阳性表达率明显低于其他类型卵巢癌,差异有显著性(P＜0.05).低分化卵巢癌的MDR1、MRP和LRP的阳性表达率分别为47.4％、78.9％和84.2％,明显高于中高分化卵巢癌的17.4％、56.5％和82.6％,差异均有显著性(P＜0.05).④16例化疗有效者的MDR1、MRP和LRP的阳性表达率分别为6.25％、25％和75％,12例化疗无效者的阳性表达率分别为58.3％、83.3％和91.7％,两者相比,MDRI和LRP的差异均有显著性(P＜ 0.05).⑤与正常卵巢和良性卵巢肿瘤组织相比,卵巢癌组织中耐药相关基因的共同表达明显增加,差异有显著性(P＜0.05).14例化疗无效者的耐药相关基因共同表达率明显高于24例化疗有效者.结论 MDR1、MRP和LRP在上皮性卵巢癌组织的表达明显增高,同表达现象普遍,并与患者的临床分期、分化程度有关,MDR1和LRP还与化疗疗效有关.     

实时荧光定量RT—PCR检测胃癌细胞中MRP2、MRP3及MRP5mRNA的表达

目的 研究多药耐药相关蛋白2(MRP2)基因及MRP3、MRP5基因在正常胃细胞系GES-1、胃癌细胞株(BGC-823)及胃癌耐药细胞株BGC-823/ADM的表达差异,并探讨其在胃癌耐药中的意义.方法 分别提取GES-1、BGC-823及BGC-823/ADM细胞的总RNA,逆转录cDNA,利用实时荧光定量PCR,根据标准品绘制标准曲线,检测MRP2、MRP3、MRP5基因的表达水平.结果 MRP2基因在胃癌耐药细胞株BGC-823/ADM细胞中的表达量明显高于在胃癌细胞株(BGC-823)的表达,而与其在正常胃细胞系GES-1的表达没有显著性差异;MRP3、MRP5基因表达量在三种细胞中均有显著性差异.结论 MRP2可能参与了胃癌的内在性耐药,而MRP3、MRP5可能与胃癌的获得性耐药有关,实时荧光定量方法是一种灵敏度高,特异性强,重复性好的定量检测方法.     

多药耐药相关蛋白基因表达与食管及贲门癌的关系

目的 探讨食管癌及贲门癌组织中多药耐药相关蛋白(MRP)基因的表达与其病理特征的关系。方法 应用逆转录酶-多聚酶链反应(RT-PCR)方法,检测了83例食管癌和贲门癌组织及28例患者45枚淋巴结中MRP基因的表达,并与相应癌旁组织进行对照分析。结果 35例食管癌和48例贲门癌组织中MRP阳性率(31.4％和16.7％)与其对应癌旁组织阳性率(5.7％和2％)比较具有显著性差异(P<0.01)。26枚转移淋巴结中,MRP阳性6例(23.1％);19枚非转移淋巴结组织未见MRP。在食管癌和贲门癌侵犯深肌层或纤维层及TNM Ⅲ,Ⅳ期的MRP阳性率(26.6％和28.8％)高于肿瘤侵犯浅肌层以下和TNM Ⅰ,Ⅱ期(10.5％和12.9％),均分布于低分化肿瘤中。对48例术后1～2年的患者随访发现,MRP阳性的肿瘤复发、转移的发生率高于MRP阴性者(P<0.05)。结论 食管、贲门癌组织中MRP基因表达增高,与转移淋巴结组织的MRP基因表达具有一致性,MRP的阳性表达除表现肿瘤的多药耐药外,还提示肿瘤预后不良。     

多药耐药相关蛋白1及其与肿瘤关系的研究进展

多药耐药（MDR）是导致临床肿瘤化疗失败的重要原因。多药耐药相关蛋白1（MRP1/ABCC1）被认为是介导肿瘤多药耐药的主要跨膜转运蛋白之一。 探究MRP1/ABCC1的结构、功能,以及与肿瘤的关系,有利于指导临床合理用药和肿瘤预后的评估。     

肺癌化疗耐药分子标志及其逆转研究

目的:探讨肺癌化疗耐药分子标志及其逆转的临床与基础应用评价。方法:采用国内外相关文献,结合我们在这一领域长期研究,深入归纳与分析。结果与结论:肺癌化疗耐药主要分子标志有多药耐药基因(MDR1)表达增加,多药耐药相关蛋白(MRP)基因表达增加,谷胱甘肽解毒酶系统活性增强和线粒体凋亡途径异常,综合采用逆转耐药分子,耐药基因siRNA和中医药结合的逆转耐药策略,为彻底攻克肺癌耐药奠定坚实研究基础。     

瓦他拉尼对乳腺癌耐药蛋白介导的肿瘤多药耐药的逆转研究

目的观察新型激酶抑制剂类抗癌药瓦他拉尼(vatalanib)逆转肿瘤细胞多药耐药(MDR)的效果,研究其对乳腺癌耐药蛋白(BCRP)、P-糖蛋白(P-gp)、多药耐药相关蛋白1(MRP1)的作用,探讨其作用机制。方法应用MTS法或SRB法检测瓦他拉尼对耐药细胞与敏感细胞的细胞毒性和逆转MDR的效果;分别以罗丹明(Rh-123)、米托蒽醌(MX)、阿霉素(ADR)为P-gp、BCRP、MRP1的荧光底物,应用流式细胞术检测该药对P-gp、BCRP、MRP1外排功能的影响;应用Western blot检测该药对耐药细胞中BCRP蛋白表达水平的影响,并研究其对细胞增殖相关信号分子的影响;应用qRT-PCR检测其对耐药细胞中BCRP基因表达水平的影响;通过超速离心法制备BCRP转运蛋白的粗膜,检测瓦他拉尼对BCRP的ATPase活性的影响。结果无毒剂量的瓦他拉尼(5μmol·L-1)可有效逆转BCRP高表达的肿瘤细胞株HEK293/ABCG2对MX、ADR和托泊替康(TOPT)的耐药,而对P-gp高表达的肿瘤细胞株K562/A02和MRP1高表达的肿瘤细胞株HEK293/ABCC1的耐药无逆转作用。该药能够下调耐药肿瘤细胞的BCRP基因和蛋白的表达水平,并具有时间和剂量依赖效应,但对BCRP外排MX的功能无明显抑制作用。该药可以激活BCRP的ATPase活性,但并不改变BCRP的构象,对耐药和敏感细胞中AKT和ERK的表达及其磷酸化水平也均无明显影响。结论瓦他拉尼可有效、特异地逆转BCRP介导的肿瘤MDR,其机制可能是通过下调耐药肿瘤细胞中BCRP基因和蛋白的表达来达到逆转MDR的效果。     

Multidrug resistance-associated protein 1 decreases the concentrations of antiepileptic drugs in cortical extracellular fluid in amygdale kindling rats

Aim:

To investigate whether multidrug resistance-associated protein 1 (MRP1) was responsible for drug resistence in refractory epilepsy in amygdale kindling rats.

Methods:

Rat amygdale kindling was used as a model of refractory epilepsy. The expression of MRP1 mRNA and protein in the brains was examined using RT-PCR and Western blot. MRP1-positive cells in the cortex and hippocampus were studied with immunohistochemical staining. The rats were intraperitoneally injected with phenytoin (50 mg/kg) or carbamazepine (20 mg/kg), and their concentrations in the cortical extracellular fluid were measured using microdialysis and HPLC. Probenecid, a MRP1 inhibitor (40 mmol/L, 50 μL) was administered through an inflow tube into the cortex 30 min before injection of the antiepileptic drugs.

Results:

The expression of MRP1 mRNA and protein was significantly up-regulated in the cortex and hippocampus in amygdale kindling rats compared with the control group. Furthermore, the number of MRP1-positive cells in the cortex and hippocampus was also significantly increased in amygdale kindling rats. Microdialysis studies showed that the concentrations of phenytoin and carbamazepine in the cortical extracellular fluid were significantly decreased in amygdale kindling rats. Pre-administration of probenecid could restore the concentrations back to their control levels.

Conclusion:

Up-regulation of MRP1 is responsible for the resistance of brain cells to antiepileptic drugs in the amygdale kindling rats.     

利福平在胆汁淤积模型中对多药耐药相关蛋白2表达的影响

目的：探究利福平对肝内胆汁淤积模型大鼠肝组织中多药耐药相关蛋白2表达的影响。方法：通过使用α-萘异硫氰酸酯（ANIT）诱导大鼠肝内胆汁淤积后,给予大鼠利福平和熊去氧胆酸治疗,其分组为空白对照组（NC组）、模型对照组（M组）、利福平治疗组（R组）、熊去氧胆酸治疗组（U组）、利福平+熊去氧胆酸治疗组（R+U组）。通过对各组大鼠血清中肝损伤相关指标进行检测、大鼠胆汁流速对比、肝组织HE染色,观察大鼠的肝脏损伤情况,再使用RT-PCR和Western-blot对大鼠肝脏组织中多药耐药相关蛋白2（MRP2）的mRNA表达水平及蛋白表达水平进行检测。同时将大鼠的肝脏组织进行体外培养24 h后使用MTT法和PI单染流式细胞术检测其细胞活性及细胞周期。结果：M组相对于NC组血清中肝损伤的相关指标谷丙转氨酶（ALT）、碱性磷酸酶（ALP）、谷草转氨酶（AST）、总胆红素（TBIL）、γ-谷氨酰转移酶（γ-GGT）明显升高（P<0.05）,同时治疗组各组与M组相比ALT、ALP、AST、TBIL、γ-GGT显著降低（P<0.05）;各组大鼠胆汁流速进行比较,M组 < R组 < U组 < R+U组 < NC组（P<0.05）;从大鼠的肝脏组织HE染色结果显示,M组大鼠肝细胞受损严重,肝细胞发生肿胀且出现中性粒细胞浸润现象,在给予治疗后,治疗组大鼠的肝细胞有不同程度的改善,细胞肿胀和浸润现象消失。在使用RT-PCR和Western-blot对各组大鼠肝脏组织中MRP2进行检测后发现,M组大鼠相对于NC组肝脏组织中MRP2 mRNA表达水平和MRP2蛋白表达水平明显下降,在经过利福平和熊去氧胆酸治疗后,R组、U组及R+U组与M组进行比较,肝脏组织中MRP2 mRNA表达水平和MRP2蛋白表达水平显著上升（P<0.05）。使用MTT法和PI单染流式细胞术对体外培养的各组大鼠肝脏组织细胞活力检测后发现,M组大鼠细胞存活率相对于NC组明显下降（P<0.05）,细胞大量停滞于G₀/G₁期,G₂/M期细胞基本消失,治疗组大鼠肝脏细胞与M组相比存活率上升,G₀/G₁期细胞比例下降（P<0.05）。结论：利福平对于ANIT诱导的大鼠肝内胆汁淤积有一定的治疗效果,同时会上调肝脏组织中MRP2的mRNA表达水平及蛋白表达水平。     

相关miRNAs对LS174T细胞中MRPs的影响

目的探讨相关miRNAs对多药耐药蛋白MRPs转录的影响。方法经脂质体瞬时转染,将pCMX-miR-328,pC-MX-miR-206及pCMX-miR-613表达质粒转入LS174T细胞,24h后采用荧光定量RT-PCR检测相关MRPs的mRNA变化。结果在LS174T细胞内过表达hsa-miR-328,能够降低MRP3的mRNA表达水平,其抑制率为0.32(P<0.05);hsa-mir-206能够降低MRP1的mRNA表达水平,其抑制率为0.35(P<0.05)。hsa-mir-613对LS174T细胞中的相关MRPs表达无影响。结论 hsa-miR-328和hsa-miR-206在LS174T细胞系中可以抑制MRP3和MRP1的转录表达。     

MRP1 and its role in anticancer drug resistance

The phenomenon of multidrug resistance (MDR) in cancer is associated with the overexpression of the ATP-binding cassette (ABC) transporter proteins, including multidrug resistance-associated protein 1 (MRP1) and P-glycoprotein. MRP1 plays an active role in protecting cells by its ability to efflux a vast array of drugs to sub-lethal levels. There has been much effort in elucidating the mechanisms of action, structure and substrates and substrate binding sites of MRP1 in the last decade. In this review, we detail our current understanding of MRP1, its clinical relevance and highlight the current environment in the search for MRP1 inhibitors. We also look at the capacity for the rapid intercellular transfer of MRP1 phenotype from spontaneously shed membrane vesicles known as microparticles and discuss the clinical and therapeutic significance of this in the context of cancer MDR.     

Evidence for Different ABC-Transporters in Caco-2 Cells Modulating Drug Uptake

Purpose. Secretory systems contribute to drug absorption in the gastrointestinal tract. The purpose of this study was the identification of members of the ATP binding cassette superfamily of secretory transport proteins that may potentially modulate drug absorption in Caco-2 cells, which are an important cellular model predicting enteral absorption of drugs. Methods. Kinetic studies as well as PCR- and Western blot studies with confluent epithelial layers of human Caco-2 cells. Results. The study demonstrates functional expression of multidrug resistance related protein (MRP) and P-glycoprotein (P-gp) in Caco-2 cells: 1) Efflux studies with the MRP specific substrate glutathion-methylfluorescein (GS-MF) showed functional activity of MRP in Caco-2 cells preloaded with the metabolic precursor of GS-MF, chloro-methylfluoresceine-diacetate, CMFDA. Excretion of GS-MF was decreased in presence of the MRP-blocker MK-571.2) Transport experiments with cyclosporin A demonstrated the functional activity of P-gp. Cellular accumulation was increased in presence of the P-gp blocking agent SDZ-PSC 833.3) The expression of the 190 kDa protein MRP and the 170 kDa protein P-gp in Caco-2 cells was shown by Western blot analysis with specific monoclonal antibodies. 4) The expression of MRP-mRNA in Caco-2 cells was detected by RT-PCR and compared with the MRP over-expressing cell line H69AR. MRP primers recognize specifically human MRP1 (GenBank accession number L05628), but not all other published sequences of MRP (MRP2-MRP6). P-gp expression on mRNA-level was also confirmed by RT-PCR. Conclusions. The data demonstrate that besides P-gp, multidrug resistance related protein (MRP) is functionally expressed in Caco-2 cells and contributes to the active excretion of substrates in this cell line.     

Interaction of hepatocyte nuclear factors in transcriptional regulation of tissue specific hormonal expression of human multidrug resistance-associated protein 2 (abcc2)

Multidrug resistance-associated protein 2 (MRP2) (ABCC2) is an ATP-binding cassette membrane protein located primarily on apical surface of hepatocytes that mediates transport of conjugated xenobiotics and endogenous compounds into bile. MRP2 is highly expressed in hepatocytes, and at lower levels in small intestines, stomach and kidney. Previous reports have characterized mammalian MRP2 promoters, but none have established the molecular mechanism(s) involved in liver enriched expression. This study aims to investigate the mechanism of hepatic MRP2 regulation.A 2130 bp of MRP2 promoter was cloned from PAC-1 clone P108G1-7, to identify putative liver specific/hormone responsive functional DNA binding sites. Using deletion analysis, site specific mutagenesis and co-transfection studies, liver specific expression was determined.MRP2 promoter-LUC constructs were highly expressed in liver cell lines compared to non-liver cells. The region extending from − 3 to+ 458 bp of MRP2 promoter starting from AUG contained the potential binding sites for CAAATT box enhancer binding protein (C/EBP), hepatocytes nuclear factor 1, 3 and 4 (HNF1, HNF3, and HNF4. Only HNF1 and HNF4 co-transfection with MRP2 luciferase increased expression. Site specific mutational analysis of HNF1 binding site indicated an important role for HNF1α. HNF4α induction of MRP2 was independent of HNF1 binding site. C/EBP, HNF3, and HNF6 inhibited HNF1α while HNF4α induced MRP2 luciferase expression and glucocorticoids stimulated MRP2 expression.This study emphasizes the complex regulation of MRP2 with HNF1α and HNF4α playing a central role. The coordinated regulation of xenobiotic transporters and oxidative conjugation may determine the adaptive responses to cellular detoxification processes.     

何首乌肝损伤模型大鼠胆汁淤积现象及相关蛋白表达研究

目的 观察经脂多糖（LPS）诱导后连续给予何首乌醇提液（AEP）7 d大鼠的肝损伤程度及胆汁淤积相关指标的变化。方法 将雄性SD大鼠随机分为5组：对照组、LPS组、LPS+对乙酰氨基酚（APAP）组、AEP组、LPS+AEP组,LPS、LPS+APAP、LPS+AEP组按大鼠体质量分别尾iv给予4 mg/kg LPS,对照组与AEP组给予等体积生理盐水;2 h后LPS+APAP组ig给予625 mg/kg APAP,AEP组与LPS+AEP组ig给予12 g/kg,每天1次,连续给药7 d,建立特异质肝损伤炎症模型。观察体质量变化,并分别于造模后2 h、14 h、5 d、8 d检测血清生化中肝功能相关指标的变化,同时收集胆汁,计算胆汁流速与密度,并检测胆汁中主要成分变化。进行肝脏系数及组织病理学检查,并对胆汁淤积相关蛋白胆盐输出泵转运蛋白（BSEP）、多药耐药蛋白2（MRP2）及多药耐药蛋白3（MRP3）进行Real-Time PCR检测。结果 经过LPS诱导2 d后,LPS+AEP组与对照组、AEP组比较体质量明显下降,5、8 d肝脏系数显著增加（P＜0.05）;血清生化指标分析结果显示,与对照组比较,LPS+AEP组丙氨酸氨基转移酶（ALT）、天门冬氨酸氨基转移酶（AST）水平无明显变化;造模后8 d的总胆红素（TBIL）明显降低（P＜0.05）,ALP明显升高（P＜0.05）;可观察到胆汁密度和胆汁流速明显降低（P＜0.05）,对胆汁成分分析显示,与对照组比较,LPS+AEP组总胆固醇（TCHO）显著升高、TBIL显著降低（P＜0.05）;病理结果显示,AEP组出现轻微肝细胞变性,而LPS+AEP组可见严重局灶坏死;转录水平结果发现,LPS诱导后可使得BSEP、MRP2在14 h时出现短期抑制（P＜0.05）,单独给予AEP可使BSEP、MRP2和MRP3的表达水平短时显著升高（P＜0.05、0.01）,而LPS+AEP给药第8 d对大鼠肝脏BSEP、MRP2无显著性影响,可使MRP3转录水平升高（P＜0.05）。结论 经LPS诱导的AEP可明显损伤大鼠肝细胞并干扰胆汁分泌功能,引起胆汁成分相关生化指标的改变,对BSEP与MRP2水平无显著影响,MRP3出现代偿性升高,提示确实存在胆汁淤积症状,但可能是存在其他机制。     

Effect of hypouricaemic and hyperuricaemic drugs on the renal urate efflux transporter, multidrug resistance protein 4

Background and purpose:

The xanthine oxidase inhibitors allopurinol and oxypurinol are used to treat hyperuricaemia, whereas loop and thiazide diuretics can cause iatrogenic hyperuricaemia. Some uricosuric drugs and salicylate have a bimodal action on urate renal excretion. The mechanisms of action of these hypo- and hyperuricaemic drugs on the handling of urate in renal tubules have not been fully elucidated. Recently, we identified the multidrug resistance protein (MRP) 4 as a luminal efflux transporter for urate in the proximal tubule.

Experimental approach:

Here, we studied the effect of these drugs on [¹⁴C]urate transport using human embryonic kidney 293 cells overexpressing human MRP4 and in membrane vesicles isolated from these cells.

Key results:

Allopurinol stimulated MRP4-mediated cellular urate efflux and allopurinol and oxypurinol both markedly stimulated urate transport by MRP4 in membrane vesicles. Bumetanide and torasemide had no effect, whereas furosemide, chlorothiazide, hydrochlorothiazide, salicylate, benzbromarone and sulfinpyrazone inhibited urate transport, at concentrations ranging from nanomolar up to millimolar. Probenecid stimulated urate transport at 0.1 μM and inhibited transport at higher concentrations.

Conclusions and implications:

These data suggest that inhibition of MRP4-mediated urate efflux by furosemide and thiazide diuretics could have an important function in their hyperuricaemic mechanisms. Furthermore, stimulation of MRP4-mediated renal urate efflux could be a new mechanism in the hypouricaemic action of allopurinol and oxypurinol. In conclusion, MRP4 may provide a potential target for drugs affecting urate homoeostasis, which needs to be further evaluated in vivo.