P—gP、MRP1、GST-П与新疆维吾尔族宫颈癌新辅助化疗疗效的相关性研究

Ig1的：探讨新疆维吾尔族宫颈癌新辅助化疗前后P-gP、MRPI和GST-П的表达及其与化疗疗效的关系。方法：运用S-P法分别检测维吾尔族妇女宫颈鳞癌组织22例新辅助化疗前后及正常宫颈组织20例P-ge、MRPI和GST-TF的表达水平。结果：①新疆维吾尔族正常宫颈、初治宫颈癌组织中P—gp的阳性表达率分别为10％、40．9％;MRP1的阳性表达率分别为15％、31．8％;GST-П的阳性表达率分别为45％、9．01％。P．gP和GST．丌在各组间比较差异均有统计学意义（P〈0．05）MRP1差异无统计学意义（P〉0．05）。@NACT后宫颈癌组织中P．Pg阳性表达显著上升（P〈0．05）,有统计学意义。NACT后宫颈癌组织中MRP1、GST-П阳性表达上升但差异无统计学意义（P〉0．05）。⑨新疆维吾尔族妇女新辅助化疗前宫颈鳞癌组织中P—gP、MRP1及GST-Tr表达阴性和阳性患者NACT有效率无显著性差异（P〉0．05）。结论：P-pg、MRP1、GST-П无法作为化疗敏感性指标预测维吾尔族宫颈鳞癌新辅助化疗疗效     

PBRM1和P21蛋白在子宫内膜癌的表达及意义

目的：探讨PBRMl和P21蛋白在子宫内膜癌中的表达和临床意义。方法：应用免疫组化方法对105例子宫内膜癌组织进行PBRMl和P21蛋白检测。结果：子宫内膜癌中PBRMl和P21的阳性表达率分别为62．86％和80％;癌旁组织PBRMl和P21阳性表达率分别为45．71％和34．2％,子宫内膜癌组织表达高于癌旁组织（P〈0．05）;PBRMl和P53阳性表达与组织学类型、浸润深度、淋巴结转移、组织学分级、临床TNM分期相关（P〈0．05）,与患者年龄无关（P〉0．05）。PBRMl和P21的表达呈正相关（P〈0．05）。结论：PBRMl和P21表达水平与子宫内膜癌组织的病理分级和临床分期的增高而增高,对其进行监测对子宫内膜癌的诊断、治疗及预后有指导意义。     

EB病毒与子宫颈癌发病的关系

目的 分析EB病毒感染与子宫颈的关系及其对抑癌基因p53表达的影响,探讨EB病毒的致癌机制。方法 采用免疫组织化学S-P法,分别检测59例宫颈鳞癌,19例正常宫颈组织的EB病毒（Epstein-Barr virus,EBV）及抑癌基因p53蛋白的表达情况,并进一步分析宫颈癌组织EBV感染与抑癌基因p53表达的关系。结果 EBV阳性表达率在宫颈癌及正常宫颈组分别为64．4％和21．1％,2组间差异有显著性（P〈0．05）;p53在宫颈癌组织中的阳性表达率为64．4％,明显高于正常宫颈组26．3％,（P〈0．05）。EBV感染与非感染的宫颈癌组织中,p53的阳性表达率分别为78．9％与38．1％,2组间差异有显著性（P〉0．05）。结论 EBV病毒感染与宫颈癌的发病密切相关,但其机制可能是通过影响抑癌基因P53表达而致癌。     

Bcl-2和COX-2在宫颈鳞癌中的表达及其临床意义

目的：观察Bcl-2和COX-2在正常宫颈和宫颈鳞癌中的表达情况,并探讨其与宫颈鳞癌发生发展的关系。方法：应用免疫组织化学s-P法检测40例宫颈鳞癌组织、10例正常宫颈组织中Bcl-2和COX-2的表达情况。结果：（1）Bcl-2在正常宫颈组织和宫颈鳞癌组织中的阳性表达率分别为30．0％、72．5％（P〈0．05）,而COX-2在正常宫颈组织和宫颈鳞癌组织中的阳性表达率分别为0．0％、60．0％（P〈0．05）。（2）在宫颈鳞癌中,Bcl-2的表达与宫颈鳞癌的病理分级、临床分期以及淋巴结转移无关（P〉0．05）,而COX-2的表达与宫颈鳞癌的病理分级及淋巴转移有关（P〈0．05）,与临床分期无关（P〉0．05）。（3）Spearman等级相关性分析显示宫颈鳞癌组织中Bcl-2和COX-2的表达呈正相关（r=0．517,P〈0．01）。结论：Bcl-2和COX-2在宫颈鳞癌中的表达升高并呈显著正相关,且COX-2的表达与宫颈鳞癌的淋巴转移有关,二者在宫颈癌的发生发展中可能起重要作用,有可能作为评估宫颈鳞癌淋巴结转移的参考指标。     

RNA干扰沉默缺氧诱导因子1α逆转肺癌细胞耐药性

目的：观察RNA干扰沉默缺氧诱导因子1α（HIF-1α）对肺癌细胞耐药性的影响。方法：构建靶向HIF-1α小干扰RNA基因,并转染到人肺腺癌耐顺铂细胞株A549／DDP细胞中。逆转录聚合酶链反应RT—PCR）检测细胞的HIF-1α、多药耐药基因-（MDR-1）以多药耐药相关蛋白基因（MRP）mRNA变化,免疫细胞化学法观察干扰后HIF-1α、P-糖蛋白以及MRP蛋白的变化。MTT法检测不同浓度的顺铂作用下细胞死亡率。结果：HIF-1αsiRNA组中H1F-1α、MDR—1、MRPmRNA水平显著降低（P〈0．05）。且蛋白水平也显著下降（P〈0．05）。HIF-1αsiRNA组细胞死亡率较未转染组均明显增高（P〈0．05）,转染siRNA阴性组不影响肿瘤细胞的耐药性。结论：HIF-1αsiRNA可显著降低A549／DDP细胞中H1F-1α、MDR-1、MRP表达,从而起到逆转肺腺癌A549／DDP细胞的耐药作用。     

缺氧环境下大鼠骨髓间充质干细胞凋亡相关蛋白和mRNA的表达

目的探讨大鼠骨髓间充质干细胞（MSCs）在缺氧环境下凋亡相关蛋白和mRNA的表达。方法将接种的P3细胞置于94％N2、1％O2和5％CO2缺氧箱中37℃孵育,分别于0．5h、1h、2h、4h、6h、8h和12h取出分别应用Annexin V／PI双染法进行流式细胞仪（FCM）分析MSCs凋亡率（Apoptotic Rate,AR）,并同步用免疫细胞化学、western blotting和Rt-PCR等方法检测Bax／Bcl-2,Fas／FasL和Caspase-3蛋白和mRNA的表达。结果1．缺氧前,免疫细胞化学法未检测到Bcl-2、Bax、Fas、FasL和Caspase-3蛋白表达,缺氧0．5h后均可较强表达;2．各缺氧时间点Bcl-2、Bax、Fas、FasL、Caspase-3蛋白和mRNA表达较缺氧前均显著性增高（P均〈0．05）;随缺氧时间延伸,Bcl-2蛋白和mRNA表达不显著增加（P〉0．05）,而Bax、Fas、FasL、Caspase-3蛋白和mRNA表达均显著增加（P均〈0．05）,但缺氧6-12h时间点之间表达均没有统计学意义（P均〉0．05）;3．AR和Bcl-2／Bax蛋白（r1=0．417,P=0．043）及mRNA（r2=-0．435,P=0．040）呈显著负相关,而和Fas（r1=0．639,P=0．025;r2=0．711,P=0．018）、Fas-L（r1=0．581,P=0．022;r2=0．605,P=0．037）、Caspase-3（r1=0．704,P=O．014;r2=0．657,P=0．026）蛋白及mRNA均呈显著正相关。结论在缺氧促进MSCs凋亡的过程中,Bcl-2蛋白和mRNA可能起着保护作用,而Bax、Fas-L、Fas、Caspase-3蛋白和mRNA可能在MsCs凋亡的进程中起着促进作用。     

HSP70和P53蛋白在甲状腺乳头状癌中的表达及其与临床病理特征的关系

目的：探讨热休克蛋白70（HSP70）和P53蛋白在甲状腺乳头状癌组织中的表达及其与临床病理特征的关系。方法：应用免疫组织化学Envision法检测35例甲状腺乳头状癌组织、15例甲状腺良性病变组织及15例正常甲状腺组织中HSP70和P53蛋白的表达,分析HSP70和P53蛋白的表达与甲状腺乳头状癌临床病理学特征的关系。结果：甲状腺乳头状癌组织中HSP70和P53阳性表达率明显高于甲状腺良性病变组织及正常甲状腺组织（P〈0．01）。HSP70在甲状腺乳头状癌组织中的表达与是否有颈部淋巴结转移、浸润深度以及AJCC分期密切相关（P〈0．01）,而与年龄、性别、肿瘤的大小以及分化程度无关（P〉0．05）。P53在PTC组织中的表达与组织分化程度、是否有淋巴结转移、浸润深度以及AJCC分期密切相关（P〈0．01）,而与年龄、性别、肿瘤的大小无关（P〉0．05）。HSP70和P53蛋白在PTC组织中的表达呈正相关性（r=0．679,P〈0．01）。结论：HSP70和p53蛋白在PTC中均呈高表达,并有协同作用,两者可作为预测PTC的生物学行为和预后的参考指标：     

胃癌组织中Survivin、P53蛋白表达和微血管密度测定及意义

目的探讨Survivin,P53蛋白在胃癌组织中的表达及其与血管生成的关系。方法用免疫组化方法对65例胃癌组织Survivin,P53,CD34的表达进行检测。结果胃癌组织中Survivin蛋白阳性表达率为70.77%（46/65）,P53蛋白阳性表达率为64.62%（42/65）。Survivin表达与分化程度和淋巴结转移有关（P〈0.05）,而与临床分期无关（P〉0.05）;P53的阳性表达与分化程度、临床分期和淋巴结转移有关（P〈0.05）。Survivin表达与P53的表达密切相关（r=0.413,P〈0.01）。Survivin阳性表达组织中的MVD值为103.04±15.06,阴性组为81.89±12.15,二者有显著差异（P〈0.01）。P53阳性表达胃癌组织中的MVD值为105.83±15.06,阴性组为81±12.71,二者有显著差异（P〈0.01）。结论Survivin和P53突变对凋亡的抑制的协同作用及其促进血管生成的作用在胃癌的发生发展中起关键作用。     

白血病耐药细胞系U937/ADR的建立及其生物学性状

目的：建立白血病耐药细胞系U937/ADR模型,并检测其多药耐药相关基因及其生物学性状的改变。方法：以大剂量阿霉素(IC50浓度),短时间(2h)暴露法诱导人白血病细胞系U937细胞的阿霉素耐药性。检测细胞的生长曲线,计算阿霉素耐药倍数,流式细胞术分析细胞周期分布;罗丹明123检测药物外排功能;荧光定量PCR（FQ-PCR）检测MDR1、MRP1、NF-Κb、Bcl-2、Bax mRNA水平变化;Western blot 检测Akt、p-Akt、P65、P-gp、MRP1和Bcl-2蛋白水平变化。结果：成功构建耐阿霉素U937/ADR细胞系,对阿霉素耐药指数为亲代U937细胞的11倍,U937/ADR群体倍增时间为43.6h,高于亲代细胞8.9h;流式细胞分析显示与U937细胞相比,U937/ADR的G0/G1期细胞增多,而G2/M期细胞减少。并对多种化疗药物产生交叉耐药性。罗丹明123外排试验显示,U937/ADR细胞外排明显增加。U937/ADR细胞MDR1、NF-Κb、Bcl-2 mRNA表达水平明显增加,P-gp及p-Akt、P65表达水平增加。结论：成功构建的U937/ADR细胞系其生物学特性明显不同与亲代U937细胞,对多种化疗药物产生多药耐药,高表达多药耐药蛋白P-gp,同时激活p-Akt及NF-Kb。     

热休克蛋白90β在结肠癌组织中的表达及其意义

目的：了解热体克蛋白90β（HSP90β）在结肠癌组织中的表达,并探讨其与肿瘤临床病理特征之间的关系。方法：运用SP免疫组织化学染色方法检测72例结肠癌组织和30例癌旁正常组织中HSP90β的表达情况,分析其与结肠癌临床病理特征之间的关系。结果：HSP90β在结肠癌组织、癌旁正常组织中的表达阳性率分别为30／72（41．67％）、5／30（16．67％）,两者间差异有统计学意义（P〈0．05）,HSP90β的表达水平与肿瘤的病理学分级之间有相关性（P〈0．05）,随着结肠癌分化程度的降低,HSP90β的阳性表达率升高,HSP90β与肿瘤Duke’s分期之间无相关（P〉0．05）。结论：HSP90β在结肠癌组织中的表达阳性率明显高于癌旁正常组织,HSP90β的高表达可能参与了结肠癌的恶性转化,有望作为结肠癌基因治疗的一个新靶点。     

p27和p53基因在大肠癌中的表达及临床意义

目的 研究大肠癌患者癌组织中p27、p53基因的表达及其相互之间的关系,以探讨p27、p53基因在大肠癌发生中的作用及临床意义。方法 运用原位杂交方法及免疫组化SP法检测58例大肠癌组织及正常黏膜中p27mRNA和P27蛋白的表达,同时运用免疫组化法分析相同组织中P53蛋白表达状况。结果 p27mRNA在大肠癌组织及正常黏膜中的表达阳性率均为100%。P27蛋白在大肠癌组织中的表达阳性率为55.17%,在正常黏膜中的表达阳性率为96.55%（P〈0.01）;癌组织中P53蛋白表达阳性率为53.45%,正常黏膜未见P53蛋白表达（P〈0.01）;大肠癌组织中P27与P53蛋白表达无明显相关性。P27蛋白的表达与肿瘤分化程度呈负相关（P〈0.01）,与临床其它病理因素均无相关性（P〉0.05）。大肠癌组织中P53蛋白表达与临床病理因素亦无相关性（P〉0.05）。结论 P27蛋白表达的调控主要在转录后水平,P27蛋白检测可作为评价大肠癌恶性程度和预后判断的重要指标。P27及P53蛋白在大肠癌的发生发展过程中具有重要作用。     

P-glycoprotein enhances radiation-induced apoptotic cell death through the regulation of miR-16 and Bcl-2 expressions in hepatocellular carcinoma cells

P-glycoprotein (Pgp), an efflux pump, was confirmed the first time to regulate the expressions of miR/gene in cells. Pgp is known to be associated with multidrug resistance. RHepG2 cells, the multidrug resistant subline of human hepatocellular carcinoma HepG2 cells, expressed higher levels of Pgp as well as miR-16, and lower level of Bcl-2 than the parental cells. In addition, RHepG2 cells were more radiation sensitive and showed more pronounced radiation-induced apoptotic cell death than the parental cells. Mechanistic analysis revealed that transfection with mdr1 specific antisense oligos suppressed radiation-induced apoptosis in HepG2 cells. On the other hand, ectopic mdr1 expression enhanced radiation-induced apoptosis in HepG2 cells, SK-HEP-1 cells, MiHa cells, and furthermore, induced miR-16 and suppressed its target gene Bcl-2 in HepG2 cells. Moreover, the enhancement effects of Pgp and miR-16 on radiation-induced apoptosis were counteracted by overexpression of Bcl-2. The Pgp effect on miR-16/Bcl-2 was suppressed by Pgp blocker verapamil indicating the importance of the efflux of Pgp substrates. The present study is the first to reveal the role of Pgp in regulation of miRNA/gene expressions. The findings may provide new perspective in understanding the biological function of Pgp.     

非小细胞肺癌中细胞凋亡与P53、Bcl-2蛋白的表达及对预后的影响

目的研究细胞凋亡及凋亡相关蛋白P53和Bcl-2在非小细胞肺癌组织中的表达水平,及其对预后的影响。方法应用DNA缺口末端标记技术和免疫组化方法检测111例肺癌患者组织中细胞凋亡、突变型P53和Bcl-2蛋白表达水平。结果111例肺癌中,细胞凋亡高表达53例(47.7%),突变型P53蛋白阳性45例(40.5%),Bcl-2蛋白阳性59例(53.2%)。COX模型多因素分析显示,淋巴结的转移和Bcl-2蛋白的阳性表达是本组肺癌患者的预后不良因素(P<0.05)。结论凋亡及凋亡相关蛋白P53和Bcl-2影响肺癌患者的生物学行为及预后。     

Interaction of ivermectin with multidrug resistance proteins (MRP1, 2 and 3)

Ivermectin is a potent antiparasitic drug from macrocyclic lactone (ML) family, which interacts with the ABC multidrug transporter P-glycoprotein (Pgp). We studied the interactions of ivermectin with the multidrug resistance proteins (MRPs) by combining cellular and subcellular approaches. The inhibition by ivermectin of substrate transport was measured in A549 cells (calcein or 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein, BCECF) and in HL60-MRP1 (calcein). Ivermectin induced calcein and BCECF retention in A549 cells (IC(50) at 1 and 2.5microM, respectively) and inhibited calcein efflux in HL60-MRP1 (IC(50)=3.8microM). The action of ivermectin on the transporters ATPase activity was followed on membranes from Sf9 cells overexpressing human Pgp, MRP1, 2 or 3. Ivermectin inhibited the Pgp, MRP1, 2 and 3 ATPase activities after stimulation by their respective activators. Ivermectin showed a rather good affinity for MRPs, mainly MRP1, in the micromolar range, although it was lower than that for Pgp. The transport of BODIPY-ivermectin was followed in cells overexpressing selectively Pgp or MRP1. In both cell lines, inhibition of the transporter activity induced intracellular retention of BODIPY-ivermectin. Our data revealed the specific interaction of ivermectin with MRP proteins, and its transport by MRP1. Although Pgp has been considered until now as the sole active transporter for this drug, the MRPs should be taken into account for the transport of ivermectin across cell membrane, modulating its disposition in addition to Pgp. This could be of importance for optimizing clinical efficacy of ML-based antiparasitic treatments. This offers fair perspectives for the use of ivermectin or non-toxic derivatives as multidrug resistance-reversing agents.     

Egr-1基因及其相关癌基因蛋白在放疗后食管鳞癌的表达

目的研究早期生长反应基因1（Egr-1基因）在放疗后切除人食管癌组织的表达及其与癌基因蛋白C－fos、C—Jun和Egr-1靶基因蛋白P53、Rb和Bax表达的关系。方法应用原位杂交和免疫组化法分别检测80例非放疗和放疗后外科切除食管鳞状细胞癌Egr－1mRNA、Egr-1、Cfos、C-Jun、P53、Rb和Bax蛋白的表达。结果Egr-1mRNA和Bax蛋白阳性定位于细胞质;而Egr-1、Fos、Jun、P53和Rb蛋白阳性定位于细胞核。40例非放疗和40例放疗后的食管癌切除肿瘤标本均存在Egr-1表达,其中40例例放疗病人外科切除标本Egr-1阳性表达9例（22．5％）,40例放疗后病人Egr-1阳性表达23例（57．5％）。Egr-1基因表达与Fos、Jun癌基因蛋白的表达无关。食管癌放疗后癌组织Egr-1超表达病人预后较好。结论放疗反应上调食管癌Egr-1表达。Egr-1超表达可作为食管鳞癌放疗反应的基因标志,并对食管鳞状细胞癌的预后判断有重要作用。     

Nucleotide triphosphatase activity of the N-terminal nucleotide-binding domains of the multidrug resistance proteins P-glycoprotein and MRP1

The multidrug resistance proteins P-glycoprotein (Pgp) and MRP1 are drug-efflux pumps. In this study, we compared the nucleotide triphosphatase activities of the isolated N-terminal nucleotide binding domains (NBD1) of Pgp and MRP1, and explored the potential role of the phosphorylation target domain of Pgp on the regulation of Pgp NBD1 ATPase activity. We found that: (1) the NBD1s of Pgp and MRP1 have ATPase and GTPase activities, (2) the K(m)s of Pgp NBD1 for ATP and GTP hydrolysis are identical, while the K(m) of MRP1 NBD1 for ATP is lower than that for GTP, and (3) phosphorylation of MLD by PKA or PKC produces a marginal increase of V(max) for ATP hydrolysis, without affecting the affinity for ATP. These results show efficient GTP hydrolysis by the NBD1s of Pgp and MRP1, and a minor role of phosphorylation in the control of Pgp NBD1 ATPase activity.     

凋亡抑制蛋白Livin和抑癌基因p53在非小细胞肺癌中的表达及临床病理学意义

目的检测livin和P53蛋白在非小细胞肺癌(NSCLC)组织中的表达并分析其临床病理学意义。方法采用免疫组织化学(SABC)的方法检测livin和P53蛋白在40例NSCLC患者肺癌组织切片中的表达,分析其与临床病理学参数之间的关系。结果40例NSCLC中livin和P53蛋白阳性表达率分别为47.5%和52.5%,在淋巴结转移的NSCLC组织中livin的阳性率明显高于无淋巴结转移的肺癌组织(P<0.05),且与肺癌不同分期有关(P<0.05)。P53蛋白表达亦与肿瘤分期有关,P53在鳞癌中的表达率显著高于腺癌(P<0.05)。P53和livin均与年龄、性别、肿瘤分化程度等临床病理学参数无关(P>0.05)。Livin与P53蛋白的表达无明显相关性(P>0.05)。结论livin与P53异常表达与NSCLC的恶性生物学行为有关,其表达对临床上判断NSCLC的预后有重要意义。     

Drug concentration-dependent expression of multidrug resistance-associated protein and P-glycoprotein in the doxorubicin-resistant acute myelogenous leukemia sublines.

The multidrug resistance of cancer cells can be mediated by an overexpression of the human MDR1 and MRP genes, which encode the transmembrane efflux pumps, the 170 kDa P-glycoprotein (Pgp) and the 190 kDa multidrug resistance-associated protein (MRP), respectively. In this study, we investigate which protein is preferentially overexpressed in the function of doxorubicin concentrations in the acute myelogenous leukemia cell line (OCI/AML-2). Multidrug-resistant AML-2 sublines were isolated in doxorubicin concentrations of 20, 100, 250, and 500 ng/ml. MRP was at first expressed at low concentrations of less than 5 x IC50 (100 ng/ml) of doxorubicin followed by the overexpression of Pgp with concentrations of more than 12.5 x IC50 (250 ng/ml) of doxorubicin. In addition, it appeared that increased amounts of MRP and its mRNA in AML-2/DX20 and /DX100 decreased gradually in both AML-2/DX250 and /DX500 overexpressing Pgp. In conclusion, it is thought that the overexpression of MRP or Pgp is dependent upon drug concentrations. It could be implicated that the overexpression of MRP might be negatively related to that of Pgp.     

Gene expression of ABC proteins in hepatocellular carcinoma,perineoplastic tissue,and liver diseases

BACKGROUND: The development of hepatocellular carcinoma (HCC) is a frequent event during the natural history of cirrhosis. Effective treatment is, however, hampered by drug resistance related to the expression of multidrug resistance (MDR) proteins belonging to the ABC family transporters. Studying expression of genes coding for these proteins may help to explain the potential sensitivity of HCC to chemotherapy. MATERIAL AND METHODS: The expression of MRP1, MRP2, MRP3, MDR1, and MDR3 was investigated by quantitative RT-PCR analyses in paraffin-embedded tissues obtained from 9 cases of HCC, 16 cases of cirrhosis, 10 cases of chronic extrahepatic cholestasis, and 16 cases of normal liver. In HCC cases, gene expression was assessed both in neoplastic and perineoplastic tissue after microscopically assisted microdissection. RESULTS: MRP1 was significantly and similarly overexpressed in HCC and perineoplastic tissue. MRP2 and MDR1 were also increased in HCC, but the level of expression did not correlate with that of perineoplastic tissue. The level of expression was either reduced or normal in cirrhotic liver and during chronic cholestasis. Expression of MDR3 was unchanged in all conditions investigated. CONCLUSIONS: The genetic expression of multi-drug resistance proteins, in particular MRP1, MRP2, and MDR1, is increased during HCC. In the case of MRP1, the extent of expression is similar in neoplastic and perineoplastic tissue, but this is not the case for MRP2 and MDR1. The assessment of ABC protein expression pattern may provide important information for the diagnosis and treatment of HCC.     

Multidrug Resistance-Related Transport Proteins in Isolated Human Brain Microvessels and in Cells Cultured from These Isolates

Abstract: The multidrug transporter, P-glycoprotein (Pgp), at the blood-brain barrier is thought to be important for limiting access of toxic agents to the brain, but controversy surrounds its cellular location, whether on endothelium or on adjacent astrocyte foot processes. In the present study, the distribution of protein and mRNA for Pgp and for another transporter, multidrug resistance-associated protein (MRP), is compared with that for the endothelial marker, platelet-endothelial cell adhesion molecule-1 (PECAM-1) and for the astrocyte-derived glial fibrillary acidic protein (GFAP) in microvessels isolated from human brain and in cells grown from these microvessels. Activities of the multidrug transporters are assessed in the cultured cells from the effects of transport inhibitors on intracellular [³H]vincristine accumulation. The isolated microvessels show strong immunocytochemical staining for Pgp and PECAM-1 and little or no staining for GFAP and MRP, and they contain mRNAs detectable by RT-PCR encoding only Pgp and PECAM-1, but not GFAP or MRP. Thus, Pgp may well be synthesised and expressed on cells within the microvessels rather than on adherent astrocyte foot processes. In cells grown from the microvessels, although PECAM-1 remains, Pgp expression decreases and MRP appears. Evidence suggests these multidrug transporters are functionally active in the cultured cells.