血清HMGA2、P-gp与老年进展性脑梗死患者预后相关研究

目的探讨血清高迁移率族蛋白A2(HMGA2)、P-糖蛋白(P-gp)在老年进展性脑梗死患者中的表达水平及其与预后的关系。方法收集2020年2月—2023年2月大连市中心医院神经内科收治老年进展性脑梗死患者67例为进展组,老年非进展性脑梗死患者79例为非进展组;进展组根据治疗后3个月神经功能恢复情况分为预后良好亚组(n=39,mRS评分0~2分)和预后不良亚组(n=28,mRS评分3~6分)。采用酶联免疫吸附法检测血清HMGA2、P-gp水平,Pearson积矩相关分析血清HMGA2、P-gp与NIHSS评分的关系,Logistic回归分析进展性脑梗死患者预后不良的影响因素,受试者工作特征曲线(ROC)评估血清HMGA2、P-gp对预后不良的预测价值。结果进展组血清HMGA2、P-gp水平及NIHSS评分高于非进展组(t/P=13.672/<0.001,8.095/<0.001,8.226/<0.001)。进展性脑梗死患者血清HMGA2、P-gp与NIHSS评分均呈正相关(r/P=0.732/<0.001、0.708/<0.001);预后不良亚组患者年龄大于预后良好亚组,血清HMGA2、P-gp水平及NIHSS评分高于预后良好亚组(t/P=5.092/<0.001、5.103/<0.001、4.449/<0.001、2.357/0.021)。多因素Logistic回归结果显示,高龄和血清HMGA2、P-gp水平及NIHSS评分升高是进展性脑梗死患者预后不良独立危险因素[OR(95%CI)=1.429(1.093~1.869),1.288(1.082~1.533),1.586(1.161~2.165),1.483(1.120~1.963)];血清HMGA2、P-gp及二者联合预测进展性脑梗死患者预后不良的AUC分别为0.738、0.740、0.895,二者联合优于各自单独预测效能(Z/P=2.031/0.002、2.006/0.003)。结论血清HMGA2、P-gp在老年进展性脑梗死患者中异常升高,并与病情严重程度以及预后不良有关,早期联合检测两项指标可预测患者预后不良风险发生。

P-gp、GSTπ联合TOPOⅡα检测对三阴性乳腺癌新辅助化疗病理完全缓解的预测价值

目的分析P⁃糖蛋白(P⁃gp)、谷胱甘肽转移酶(GSTπ)联合拓扑异构酶Ⅱα(TOPOⅡα)检测对三阴性乳腺癌(TNBC)患者新辅助化疗(NAC)病理完全缓解(pCR)的预测价值。方法本研究为一项回顾性、单中心、双盲法的试验,选取郑州大学第一附属医院自2020年3月至2022年10月,经纳入、排除标准共筛查135名TNBC患者作为研究对象,均为女性。采用SP免疫组化法检测P⁃gp、GSTπ、TOPOⅡα,分析TNBC患者NAC疗效,行单因素、多因素分析P⁃gp、GSTπ、TOPOⅡα表达与NAC pCR的关系,绘制ROC曲线分析P⁃gp、GSTπ、TOPOⅡα单一及联合检测对TNBC患者NAC pCR的预测价值。结果NAC后,cCR者47例(34.81%),cPR者72例(53.33%),SD者12例(8.90%),PD者4例(2.96%),总有效率88.14%;pCR者21例(15.55%)。经单因素分析,P⁃gp、GSTπ阳性表达pCR率低于P⁃gp、GSTπ阴性表达pCR率,TOPOⅡα阳性表达pCR率则高于阴性性表达pCR率,差异均有统计学意义(P<0.05)。P⁃gp、GSTπ、TOPOⅡα表达与pCR具有显著相关性[OR(95%CI)分别为1.446(1.127~1.858)、1.640(1.304~2.063)、1.548(1.227~1.984),P<0.05]。P⁃gp、GSTπ、TOPOⅡα联合检测对NAC pCR灵敏度、特异度分别为90.73%、86.73%,AUC(95%CI)为0.813(0.743~0.908),均高于上述指标单一检测(P<0.05)。结论P⁃gp、GSTπ和TOPOⅡα表达与TNBC患者NAC pCR有一定关联,且通过联合上述指标检测NAC pCR有着较高预测价值,有利于帮助临床医生为TNBC患者进一步制定更合适的治疗策略。

基于P-糖蛋白信号通路研究龙血竭对大鼠失重空肠屏障损伤的保护机制

传统中药龙血竭在航天肠道损伤的防护中发挥重要作用,但其保护失重屏障损伤的作用机制尚不清楚.P-糖蛋白(P-glycoprotein,P-gp)是肠上皮细胞膜上的外排转运体,能够将毒素、有害菌等外排以维持肠屏障完整性.文中采用大鼠尾吊模型模拟微重力效应,灌胃给药龙血竭(Dragon’s Blood,DB)21d后,观察大鼠空肠组织形态、测定肠屏障通透性标志物质量浓度、检测P-gp与Wnt/β-Catenin信号通路相关蛋白的表达.结果表明,龙血竭可通过激活Wnt/β-Catenin信号通路促进空肠中P-gp基因及蛋白的表达,能够缓解模拟微重力效应下的大鼠空肠屏障损伤.研究结果或可为航天员在轨肠道损伤防护提供基础研究数据.

Effect of Cyclooxygenase Inhibition on P-Glycoprotein Expression and Phenytoin Level in Brain Tissue of Pilocarpine Induced Epilepsy in Rats

Background: Increased brain P-glycoprotein (P-gp) expression may play important role in resistance to antiseizure drugs. The present work aimed to overcome the drug resistance that develop due to overexpression of P-gp with subsequent increase in brain phenytoin level in epileptic rats, using either non-selective (indomethacin) or selective (celecoxib) cyclooxygenase inhibitors. Methods: Fifty-six adult male albino rats were randomly divided into seven groups. Epilepsy was induced using the lithium pilocarpine model. Rats received indomethacin (2.5 mg/kg) or celecoxib (20 mg/kg), either alone or combined with phenytoin (50 mg/kg). Seizures were evaluated using Racine score. Motor coordination was assessed using open field and rotarod tests. Phenytoin brain level was measured using High Performance Liquid Chromatography (HPLC), glutamate expression was measured using Enzyme Linked Immunosorbent Assay (ELISA), ATP Binding Cassette Subfamily B Member 1 (ABCB1) gene expression was assessed using Real Time-Polymerase Chain Reaction (RT-PCR), and immunohistochemical analysis was done for P-gp expression. Results: Phenytoin combination with either indomethacin or celecoxib had improved the Racine score, motor coordination on rotarod apparatus, and open field test results. Also, phenytoin combination with either indomethacin or celecoxib decreased brain glutamate level, ABCB1 gene and P-gp expression, and increased brain phenytoin level compared to treatment with phenytoin alone. This indicated that both P-gp inhibitors indomethacin and celecoxib, increased the level of phenytoin that reached the brain of rats. However, brain uptake of phenytoin was significantly enhanced using celecoxib rather than indomethacin (CI 95%, 17.092: 32.808, P-value Conclusion: Cyclooxygenase inhibition using either celecoxib or indomethacin resulted in downregulation of P-gp expression, with subsequent increase in brain phenytoin level in epileptic rats.

慢性非缺血性心力衰竭患者血小板PAC-1和CD62p的表达及其与心功能的关系

目的探讨慢性非缺血性心力衰竭患者血小板膜糖蛋白纤维蛋白原受体(PAC-1)和P选择素(CD62p)的表达及其与心功能的关系。方法选取2019年1月至2022年1月天津市南开医院收治的185例慢性非缺血性心力衰竭患者作为观察组,根据纽约心脏病学会(NYHA)心功能分级将观察组患者分为心功能Ⅱ级组58例、心功能Ⅲ级组88例和心功能Ⅳ级组39例,根据左室射血分数(LVEF)将观察组患者分为射血分数保留心衰组(HFpEF)123例、射血分数临界值心衰组(HFmrEF)25例和射血分数下降心衰组(HFrEF)37例,再以B型钠尿肽(BNP)中位数为界将观察组患者分为高BNP组109例和低BNP组76例;另选取同期心功能正常的就诊者55例作为对照组。比较各组患者的基本临床信息、生化、BNP指标和PAC-1、CD62p的表达水平,采用Pearson相关分析法分析PAC-1、CD62p水平与BNP、LVEF的关系。结果观察组患者的PAC-1、CD62p水平分别为(23.67±16.54)%、(10.43±9.19)%,明显高于对照组的(9.33±9.63)%、(4.24±5.49)%,差异均有统计学意义(P<0.05);不同心功能分级患者对比发现,PAC-1、BNP水平为Ⅳ级>Ⅲ级>Ⅱ级>对照组,CD62p水平为Ⅳ级>Ⅲ级、Ⅱ级>对照组,差异均有统计学意义(P<0.05);不同LVEF分级患者对比发现,PAC-1水平为HFrEF组>HFmrEF组、HFpEF组>对照组,BNP水平为HFrEF组>HFmrEF组>HFpEF组>对照组,HFpEF组、HFmrEF组、HFrEF组CD62p水平分别为(10.72±9.17)%、(9.87±11.19)%、(9.84±7.88)%,明显高于对照组的(4.24±5.49)%,差异均有统计学意义(P<0.05);高BNP组患者的PAC-1、CD62p分别为(26.97±16.94)%、(11.05±9.62)%,明显高于低BNP组的(13.80±12.82)%、(6.97±7.54)%,差异均有统计学意义(P<0.05);经Pearson相关分析结果显示,PAC-1、CD62p与BNP呈正相关(r=0.363、0.182,P<0.05),PAC-1与LVEF呈负相关(r=-0.297,P<0.05)。结论慢性非缺血性心力衰竭患者的PAC-1、CD62p水平均明显增高,且与心功能有关,检测其水平有助于为患者的病情评估及临床治疗提供参考依据。

局灶性脑缺血大鼠脑内mdr1／P-glycoprotein表达的变化

目的观察大鼠局灶性脑缺血损害后脑内mdr1／P—glycoprotein的表达变化。方法大鼠大脑中动脉栓塞法(MCAO法)制作局灶性脑缺血模型,脑切片免疫组织化学染色检测mdr-1／P—glycoprotein在脑内的表达部位及表达时程的变化。结果 mdr-1／P—glycoprootein在缺血侧皮层和纹状体的血管内皮细胞表达增多,并出现在同侧损伤部位的神经元,其在损伤后2h开始出现,6h达到高峰,之后开始下降,到24h不能被检测到。结论大脑中动脉阻塞后可以诱导缺血损伤侧的血管内皮细胞P—glycoprotein过量表达,而同侧的神经元短暂表达P-glyco- protein．

海胆胚胎不同发育期P-糖蛋白(P-glycoprotein)药物外排功能的研究

通过研究添加维拉帕米(Verapamil,VER)后,灭蝇胺(Cyromazine)和杀虫丹(Ethiofencarb)对海胆胚胎致死中浓度(LC50)的变化,探讨了不同发育期海胆胚胎P-糖蛋白(P-glycoprotein,P-gp)的功能.结果表明:灭蝇胺和杀虫丹对海胆胚胎的平均LC50分别为2.50mg·L-1和3.50mg·L-1,在加入0.75μmol·L-1P-gp抑制剂VER后,其LC50平均降低40%～42%,说明海胆胚胎P-gp具有药物外排作用.药物浓度可影响P-gp功能,随药物浓度的升高,P-gp外排功能逐渐减弱,甚至达到饱和.实验同时通过分子模拟方法研究了灭蝇胺和杀虫丹的分子结构特征,实验和理论结果均证实了这两种药物分子为海胆胚胎P-gp的底物.

核偏最小二乘法及其在P-glycoprotein抑制剂设计中应用

介绍了一个新的基于优化推导出的核偏最小二乘(kernel partial least squares,K-PLS)的算法原理和实现步骤,并且给出了利用K-PLS法构建P-糖蛋白(P-glycoprotein,P-gp)黄酮类抑制剂的定量构效关系(QSAR)模型.利用该方法结合几个简单的分子拓扑参数,构建了具有高准确率的预测模型.该模型将有助于P-gp黄酮类抑制剂的虚拟筛选和理性设计.结果证明K-PLS是一个十分稳定可靠的方法,将会在化学计量学领域得到较好的应用和推广.

P-glycoprotein的新功能在肿瘤研究中的进展

肿瘤多药耐药性(multiple drug resistance,MDR)的发生往往伴随着多药耐药基因如MDR1、MRP1和BCRP等高表达,其中MDR1基因编码的P-糖蛋白(P-glycoprotein,P-gp)是目前公认可以诱发癌细胞发生MDR的重要分子。传统研究认为P-gp主要是作为一个药物泵将化疗药物从细胞内排出从而导致MDR。然而系列研究发现,除了介导MDR以外,P-gp还能够调节癌细胞的生长、增殖、凋亡、迁移和侵袭等其他生物学行为;而且研究表明P-gp的这些作用可以依赖,也可以不依赖于其药物泵的功能。这些结果表明P-gp能够通过一些新的机制促进肿瘤的进展。本文主要针对P-gp在促进肿瘤进展中的作用进行综述。

The Effect of Different Interventional Treatment on P-Glycoprotein in Different Histopathological Types and Grades of Primary Hepatocellular Carcinoma

To study the effect of the different interventional treatment on P Glycoprotein (Pgp) in different histopathological types of primary hepatocellular carcinoma (PHC), 98 surgically and histologically verified PHC specimens were obtained. The patients included 57 patients treated by surgical resection alone and 41 patients receiving second stage surgical resection after four kinds of interventional treatment. SABC immunohistochemical staining with a monoclonal antibody against human Pgp was used to observe the Pgp in all specimens. The positive rate of Pgp was 100 % in group of chemotherapy alone ( P <0.05), 62.5 % in group of chemotherapy combined with iodized oil ( P >0.05), 46.6 % in group of chemotherapy combined with iodized oil and spongia gelatini absorbens (Sga) ( P >0.05), 18.18 % in group of chemotherapy combined with Ethanol iodized oil and Sga ( P <0.05) and 52.63 % in group of surgical resection alone. The positive rate of Pgp varied with different histopathological types, with rate of clear cell PHC being the lowest, and that of poorly differentiated or undifferentiated PHC the highest. The positive rate of Pgp was increased as pathological grades increased. Overexpression of Pgp may be responsible for the intrinsic and acquired drug resistance of PHC. Multidrug resistance (MDR) varied with different histological types. Therapy of PHC should be tailored according to individual. Local chemotherapy combined with ethanol iodized oil and Sga embolization may become a new way to overcome MDR of PHC.

sgp130对糖尿病小鼠视网膜p-STAT3及VEGF-A表达的影响

目的:观察可溶性糖蛋白130(sgp130)对糖尿病(DM)小鼠视网膜p-STAT3及VEGF-A表达的影响,探讨sgp130防治糖尿病视网膜病变(DR)炎性损害的可能性。方法:小鼠45只被随机分为正常组、DM组和sgp130组。采用链脲佐菌素对DM组和sgp130组进行DM造模。正常组、DM组不做特殊干预,sgp130组在第1、5wk被给予1.5mg/mL sgp1302μL进行玻璃体腔注射治疗。10wk后处死所有小鼠,检查视网膜组织IL-6、p-STAT3、VEGF-A等蛋白的表达。结果:在第10wk时,DM组视网膜IL-6、p-STAT3、VEGF-A表达较正常组升高(均P<0.01)。sgp130组p-STAT3、VEGF-A表达水平较DM组低(均P<0.01)。结论:sgp130可以选择性拮抗IL-6反式信号传导通路,下调下游炎性因子VEGF-A的表达,可以用于干预DM引起的IL-6相关性视网膜炎性损害。

Overexpression of P-glycoprotein in hepatocellular carcinoma and its clinical implication

INTRODUCTIONMost advanced hepatocellular garcinoma (HCC) isinsensitive to most anticancer drugs which might berelated to the high frequency of expression of themultidrug resistance-1(MDR1) gene and itsproduct,P-glycoprotein (p-gp).p-gp expressionmay also be concerned with tumor progression anddifferentiation.In the present study。

JNK1,JNK2,and JNK3 are involved in P-glycoprotein-mediated multidrug resistance of hepatocellular carcinoma cells

BACKGROUND:Multidrug resistance(MDR)is extremely common in hepatocellular carcinoma(HCC)and is a major problem in cancer eradication by limiting the efficacy of chemotherapy.Modulation of c-Jun NH2-terminal kinase(JNK)activation could be a new method to reverse MDR.However,the relationship between JNK activity and MDR in HCC cells is unknown.This study aimed to explore the relationship between MDR and JNK in HCC cell lines with different degrees of MDR.METHODS:A MDR human HCC cell line,SMMC-7721/ ADM,was developed by exposing parental cells to gradually increasing concentrations of adriamycin.The MTT assay was used to determine drug sensitivity.Flow cytometry was used to analyze the cell cycle distribution and to measure the expression levels of P-glycoprotein(P-gp)and MDR-related protein(MRP)-1 in these cells.JNK1,JNK2 and JNK3 mRNA expression levels were quantified by real-time PCR.Expression and phosphorylation of JNK1,JNK2,and JNK3 were analyzed by Western blotting.RESULTS:The MDR of SMMC-7721/ADM cells resistant to 0.05 mg/L adriamycin was mainly attributed to the overexpression of P-gp but not MRP1.In addition,these cells had a significant increase in percentage in the S phase,accompanied by a decrease in percentage in the G0/G1 phase,which is likely associated with a reduced ability for cell proliferation and MDR generation.We found that JNK1,JNK2,and JNK3 activities were negatively correlated with the degree of MDR in HCC cells.CONCLUSION:This study suggests that JNK1,JNK2,and JNK3 activities are negatively correlated with the degree of MDR in HCC cells.

菌草灵芝多糖肽对Caco-2细胞MDR1、MRP2基因表达水平的影响

使用CCK-8比色法研究菌草灵芝多糖肽(JCGLPP)对人结肠腺癌上皮细胞(Caco-2)存活率的影响;采用PCR检测JCGLPP作用不同时间后对Caco-2细胞中P-糖蛋白的编码基因MDR1和多药耐药相关蛋白-2的编码基因MRP2表达水平的影响.结果显示:0.1~500μg·mL^(-1)JCGLPP对Caco-2细胞无毒性;10μg·mL^(-1)JCGLPP作用1~48 h能抑制MDR1基因的表达,对MRP2基因的表达呈先抑后扬的趋势.表明JCGLPP可抑制MDR1基因的表达,对MRP2基因表达的影响与其作用时间有关.

Overexpression of P-glycoprotein induces acquired resistance to imatinib in chronic myelogenous leukemia cells

Imatinib,a breakpoint cluster region(BCR)-Abelson murine leukemia(ABL) tyrosine kinase inhibitor(TKI),has revolutionized the treatment of chronic myelogenous leukemia(CML).However,development of multidrug resistance(MDR) limits the use of imatinib.In the present study,we aimed to investigate the mechanisms of cellular resistance to imatinib in CML.Therefore,we established an imatinib-resistant human CML cell line(K562-imatinib) through a stepwise selection process.While characterizing the phenotype of these cells,we found that K562-imatinib cells were 124.6-fold more resistant to imatinib than parental K562 cells.In addition,these cells were cross-resistant to second-and third-generation BCR-ABL TKIs.Western blot analysis and reverse transcription-polymerase chain reaction(RT-PCR) demonstrated that P-glycoprotein(P-gp) and MDR1 mRNA levels were increased in K562-imatinib cells.In addition,accumulation of [14C]6-mercaptopurine(6-MP) was decreased,whereas the ATP-dependent efflux of [14C]6-MP and [3H]methotrexate transport were increased in K562-imatinib cells.These data suggest that the overexpression of P-gp may play a crucial role in acquired resistance to imatinib in CML K562-imatinib cells.

多西他赛治疗老年前列腺癌患者的疗效及其对患者P-糖蛋白表达的影响分析

目的 探讨老年前列腺癌患者治疗中多西他赛的应用效果及其对P-糖蛋白表达的影响。方法 73例老年前列腺癌患者,经随机数字表法分为对照组(36例)与研究组(37例)。对照组采用比卡鲁胺治疗,研究组采用比卡鲁胺联合多西他赛治疗。对比两组P-糖蛋白表达、临床疗效及治疗前后生活质量。结果 治疗后,研究组治疗总有效率81.08%高于对照组的55.56%,差异有统计学意义(P<0.05);研究组P-糖蛋白阳性表达率18.92%低于对照组的58.33%,差异有统计学意义(P<0.05);治疗后,两组物质生活、躯体功能、社会功能及心理功能评分均明显高于本组治疗前,研究组物质生活评分(74.26±3.46)分、躯体功能评分(86.14±5.31)分、社会功能评分(81.36±3.61)分、心理功能评分(79.84±4.51)分均明显高于对照组的(62.14±3.47)、(76.58±5.28)、(72.64±3.56)、(71.16±4.48)分,差异有统计学意义(P<0.05)。结论 老年前列腺癌患者治疗中应用多西他赛,可有效降低P-糖蛋白阳性表达率,有效提高治疗效果,生活质量明显改善,具有推广价值。

Disease control by regulation of P-glycoprotein on lymphocytes in patients with rheumatoid arthritis

The main purpose of treatment of rheumatoid arthritis(RA) with disease modifying antirheumatic drugs(DMARDs) is to control activation of lymphocytes,although some patients do not respond adequately to such treatment. Among various mechanisms of multidrug resistance, P-glycoprotein(P-gp), a member of ATP-binding cassette transporters, causes drugresistance by efflux of intracellular drugs. Certain stimuli,such as tumor necrosis factor-α, activate lymphocytes and induce P-gp expression on lymphocytes, as evident in active RA. Studies from our laboratories showed spontaneous nuclear accumulation of human Y-boxbinding protein-1, a multidrug resistance 1 transcription factor, in unstimulated lymphocytes, and surface overexpression of P-gp on peripheral lymphocytes of RA patients with high disease activity. The significant correlation between P-gp expression level and RA disease activity is associated with active efflux of drugs from the lymphocyte cytoplasm and in drugresistance.However, the use of biological agents that reduce P-gp expression as well as P-gp antagonists(e.g., cyclosporine) can successfully reduce the efflux of corticosteroids from lymphocytes in vitro, suggesting that both types of drugs can be used to overcome drug-resistance and improve clinical outcome. We conclude that lymphocytes activated by various stimuli in RA patients with highly active disease acquire P-gpmediated multidrug resistance against corticosteroids and probably some DMARDs, which are substrates of P-gp. Inhibition/reduction of P-gp could overcome such drug resistance. Expression of P-gp on lymphocytes is a promising marker of drug resistance and a suitable therapeutic target to prevent drug resistance in patients with active RA.

低氧对Caco-2细胞P-gp表达及功能的影响

目的:低氧会改变许多药物的口服生物利用度,其中也包括多种P糖蛋白(P-glycoprotein,P-gp)的底物(药物),提示低氧可能影响肠上皮细胞P-gp的功能。Caco-2细胞单层膜模型是当前研究肠上皮P-gp功能的经典模型。本研究通过结合Caco-2细胞单层膜模型与低氧处理,研究低氧对Caco-2细胞P-gp表达和功能的影响,有助于阐明高原低氧环境改变肠上皮药物转运的机制。方法:正常培养的Caco-2细胞在1%的O_(2)浓度条件下分别培养24、48、72 h,提取膜蛋白后,采用蛋白质印迹法检测P-gp的表达水平,选择表达变化最显著的缺氧时间用于后续研究。于transwell小室中培养Caco-2细胞21 d,建立Caco-2细胞单层膜模型后,将其分为常氧对照组与低氧组,常氧对照组以正常条件继续培养72 h,低氧组在1%的O_(2)浓度条件下继续培养72 h,通过跨膜电阻(transepithelial electrical resistance,TEER)、荧光黄表观渗透系数(apparent permeability coefficient,Papp)、碱性磷酸酶(alkaline phosphatase,AKP)活性及透射电镜下观察微绒毛与紧密连接结构,评价Caco-2细胞单层膜的完整性和极化状态。采用双向转运实验检测P-gp特异性底物罗丹明123(rhodamine 123,Rh123)的Papp,计算外排率。将Caco-2细胞在塑料培养瓶中连续培养21 d形成Caco-2细胞单层膜,在1%O_(2)浓度条件下处理72 h后,采用蛋白质印迹法检测膜蛋白中P-gp的表达水平。结果:1%的O_(2)浓度处理下调Caco-2细胞P-gp的表达,其中处理72 h下调最为显著(P<0.01);低氧组Caco-2细胞单层膜TEER大于400Ω·cm^(2),荧光黄Papp小于5×10^(-7)cm/s,肠腔侧与基底侧AKP活性比值大于3。表明Caco-2细胞单层膜模型建立成功,且低氧处理未影响模型的完整性与极化状态。与常氧对照组相比,低氧组Caco-2细胞单层膜Rh123的外排率显著降低(P<0.01);1%的O_(2)浓度培养72 h,下调Caco-2细胞单层膜P-gp的表达(P<0.01)。结论:低氧抑制Caco-2细胞P-gp功能,其可能与P-gp表达水平降低有关。

Mitochondrial expression and activity of P-glycoprotein under oxidative stress in outer blood-retinal barrier

AIM： To investigate the role of oxidative stress in regulating the functional expression of P-glycoprotein（P-gp） in mitochondria of D407 cells.METHODS： D407 cells were exposed to different ranges of concentrations of H2O2. The mitochondrial location of P-gp in the cells subjected to oxidative stress was detected by confocal analysis. Expression of P-gp in isolated mitochondria was assessed by Western blot. The pump activity of P-gp was evaluated by performing the efflux study on isolated mitochondria with Rhodamine 123（Rho-123） alone and in the presence of P-gp inhibitor（Tariquidar） using flow cytometry analysis. The cells were pretreated with 10 mmol/L N-acetylcysteine（NAC） for 30 min before exposing to H2O2, and analyzed the mitochondrial extracts by Western blot and flow cytometry.RESULTS： P-gp was co-localized in the mitochondria by confocal laser scanning microscopy, and it was also detected in the mitochondria of D407 cells using Western blot. Exposure to increasing concentrations of H2O2 led to gradually increased expression and location of P-gp in the mitochondria of cells. Rho-123 efflux assay showed higher uptake of Rho-123 on isolated mitochondria in the presence of Tariquidar both in normal and oxidative stress state. H2O2 up-regulated P-gp in D407 cells, which could be reversed by NAC treatment. CONCLUSION： H2O2 could up-regulate the functional expression of P-gp in mitochondria of D407 cells, while antioxidants might suppress oxidative-stress-induced over-expression of functional P-gp. It is indicative that limiting the mitochondrial P-gp transport in retinal pigment epithelium cells would be to improve the effect of mitochondria-targeted antioxidant therapy in age-related macular degeneration-like retinopathy.

Dynamic expression of P-glycoprotein in the CA1,CA3 and dentate gyrus of the rat hippocampus following lithium-pilocarpine-induced status epilepticus

Epileptic seizures induce overexpression of P-glycoprotein in the blood-brain barrier. However, it is unclear whether hippocampal neurons also overexpress P-glycoprotein following seizure. This study confirmed that the clinical manifestation, pathological characteristics and electroencephalography in the rat model of lithium-pilocarpine-induced mesial temporal lobe epilepsy were consistent with clinical reports of mesial temporal lobe epilepsy in humans.Immunohistochemistry staining demonstrated that P-glycoprotein positive staining was found in neurons in the pyramidal layer of the hippocampus. Westem blot assay and real-time polymerase chain reaction revealed that P-glycoprotein overexpression was exhibited in the CA1, CA3, and dentate gyrus of the hippocampus at 24 and 60 days following model induction, but no significant dffierence was detected in the same region at various time points. These results indicate that seizures led to overexpression of P-glycoprotein in neurons of the hippocampus, but no evidence was found for a positive association between P-glycoprotein expression and seizure frequency.