Breast cancer resistance protein(BCRP/ABCG2):its role in multidrug resistance and regulation of its gene expression

Breast cancer resistance protein(BCRP)/ATP-binding cassette subfamily G member 2(ABCG2) is an ATP-binding cassette(ABC) transporter identified as a molecular cause of multidrug resistance(MDR) in diverse cancer cells.BCRP physiologically functions as a part of a self-defense mechanism for the organism;it enhances elimination of toxic xenobiotic substances and harmful agents in the gut and biliary tract,as well as through the blood-brain,placental,and possibly blood-testis barriers.BCRP recognizes and transports numerous anticancer drugs including conventional chemotherapeutic and targeted small therapeutic molecules relatively new in clinical use.Thus,BCRP expression in cancer cells directly causes MDR by active efflux of anticancer drugs.Because BCRP is also known to be a stem cell marker,its expression in cancer cells could be a manifestation of metabolic and signaling pathways that confer multiple mechanisms of drug resistance,self-renewal(stemness),and invasiveness(aggressiveness),and thereby impart a poor prognosis.Therefore,blocking BCRP-mediated active efflux may provide a therapeutic benefit for cancers.Delineating the precise molecular mechanisms for BCRP gene expression may lead to identification of a novel molecular target to modulate BCRP-mediated MDR.Current evidence suggests that BCRP gene transcription is regulated by a number of trans-acting elements including hypoxia inducible factor 1α,estrogen receptor,and peroxisome proliferator-activated receptor.Furthermore,alternative promoter usage,demethylation of the BCRP promoter,and histone modification are likely associated with drug-induced BCRP overexpression in cancer cells.Finally,PI3K/AKT signaling may play a critical role in modulating BCRP function under a variety of conditions.These biological events seem involved in a complicated manner.Untangling the events would be an essential first step to developing a method to modulate BCRP function to aid patients with cancer.This review will present a synopsis of the impact of BCRP-mediated MDR in cancer cells,and the molecular mechanisms of acquired MDR currently postulated in a variety of human cancers.

Expression of multidrug resistance 1 gene and C3435T genetic polymorphism in peripheral blood of patients with intractable epilepsy

BACKGROUND： Increased expression of multidrug resistance 1 （MDR1） mRNA in peripheral blood of patients with intractable epilepsy is not due to epilepsy drugs, but epilepsy behavior. Monitoring MDR1 expression in peripheral blood is a target for MDR1 gene evaluation. OBJECTIVE： To investigate the influence of antiepileptic drugs and seizures on MDR expression in intractable epilepsy, and to analyze the genetic polymorphisms of C3435T in the MDRl gene. DESIGN, TIME AND SETTING： Factorial designs and comparative observations at the experimental center of the Affiliated Hospital of Qingdao Medical College, Qingdao University between October 2003 and October 2004. PARTICIPANTS： A total of 120 subjects were recruited from the epilepsy clinical department of the Affiliated Hospital of Qingdao Medical College. Four groups （n = 30） were classified according to statistical factorial design： intractable epilepsy, treatment response, no treatment, and normal control groups. METHODS： One-step semi-quantitative reverse-transcription polymerase chain reaction technology was used to test expressions of the MDR1 gene in 120 subjects. C3435T polymorphisms in intractable epilepsy group and normal control groups were analyzed by polymerase chain reaction-restriction fragment length polymorphism. MAIN OUTCOME MEASURES： Expression of MDR1 mRNA in the four groups, and C3435T genetic polymorphisms in intractable epilepsy and normal control groups. RESULTS： MDRl gene expression was increased in the intractable epilepsy group, due to the factor seizures, but not the antiepileptic drugs. However, the interaction between the two factors was not statistically significant. Of the 30 subjects in the intractable epilepsy group, the following genotypes were exhibited： 3 （10%） C/C genotype, 9 （30%） C/T genotype, and 18 （60%） T/T genotype at the site of C3435T, while 4 （13%）, 10 （33%）, and 16 （53%） subjects were determined to express these genotypes in the normal control group, respectively. C and T allele frequency were 25% and 75% in the intractable epilepsy group, and 30% and 70% in the normal control group, respectively. However, there was no statistical difference between the groups. CONCLUSION： Results demonstrated that seizures, not antiepileptic drugs, induced MDR1 gene expression in intractable epilepsy. Genetic polymorphisms of C3435T in the MDR1 gene did not contribute to the development of multidrug resistance in patients with intractable epilepsy.

Congenital expression of mdr-1 gene in tissues of carcinoma and its relation with patho morphology and prognosis

ＮＴＲＯＤＵＣＴＩＯＮＭｕｌｔｉｄｒｕｇｒｅｓｉｓｔａｎｃｅ（ＭＤＲ）ｏｆｍａｌｉｇｎａｎｔｔｕｍｏｒｃｅｌｈａｓａｒｏｕｓｅｄｗｉｄｅｓｐｒｅａｄｉｎｔｅｒｅｓｔ．ＩｔｈａｓｂｅｅｎｓｈｏｗｎｔｈａｔＭＤＲｉｓｐｒｅｓｅｎｔｉｎｍａｎｙｍａｌｉｇｎ...

Detection and clinical significance of multidrug resistance-1 mRNA in bone marrow cells in children with acute lymphoblastic leukemia by real-time fluorescence quantitative RT-PCR

Objective： Multidrug resistance（MDR） is one of the most important reasons for treatment failure and recurrence of acute leukemia. Its manifestations are different in children with acute lymphoblastic leukemia（ALL） which may be due to different detection methods. This study was to detect the expression of MDR1 mRNA in bone marrow cells of children with ALL by real-time fluorescence- quantitative reverse transcription polymerase-chain reaction（FQ-RT-PCR）, and combine minimal residual desease（MRD） detection by flow cytometry（FCM） and to study their relationship with treatment response and prognosis of ALL. Methods：The MDR1 mRNA levels in bone marrow cells from 67 children with ALL[28 had newly diagnosed disease, 27 had achieved complete remission（CR）, 12 recurrent] and 22 children without leukemia were detected by FQ-RT-PCR. MRD was detected by FCM. The patients were observed for 9-101 months, with a median of 64 months. Results：Standard curves of human MDR1 and GAPDH genes were constructed successfully. MDR1 mRNA was detected in all children with a positive rate of 100%. The mRNA level of MDR1 was similar among the newly diagnosed ALL group, CR group, and control group（P 〉 0.05）, but significantly higher in the recurrence group than that in newly diagnosed disease group and control group（0.50 ± 0.55 vs. 0.09 ± 0.26 and 0.12 ± 0.23, P〈 0.05）. 54 ALL patients were followed up, and it was found that MDR1 mRNA level was significantly higher in ALL patients within 3 years duration than that of ALL patients with 3-6 years and over 6 years duration（0.63 ± 0.56 vs. 0.11 ± 0.12 and 0.04 ± 0.06, P〈 0.01）. For the 28 children with newly diagnosed disease, the MDR1 mRNA level was similar between WBC 〉 50 ~ 109 group and WBC〈50 × 10^9 group（P〉 0.05）. In the 33 CR patients, the MDR1 mRNA level was significantly higher in MRD〉10a group than that in MRD〈10a group（0.39 ± 0.47 vs. 0.03 ± 0.03, P 〈 0.05）. Conclusion：The sensitivity and specificity of FQ-RT-PCR in detecting MDR1 mRNA in bone marrowy cells of children with ALL patients are high. MDR1 mRNA is expressed in children with and without leukemia. MDR1 mRNA is highly expressed in the CR ALL patients with high MRD, recurrence and short duration（within 3 years）. Monitoring MRD and the MDR1 mRNA level might be helpful for individual treatment.

RNA干扰沉默mdrl基因联合阿霉素对卵巢癌耐药细胞株SKOV_3/ADM增殖的抑制作用

目的:观察RNA干扰沉默mdrl基因后化疗药物对卵巢癌耐药细胞株SKOV3 /ADM增殖的影响。方法:RT -PCR检测靶向于mdrl基因的小发夹状RNA(pshRNA -mdrl)对SKOV3 /ADM细胞内mdr1mRNA表达的影响;采用MTT法及软琼脂克隆形成实验测定pshRNA -mdrl联合化疗药物阿霉素对SKOV3 /ADM的增殖抑制作用。结果:pshRNA -mdrl能抑制SKOV3 /ADM细胞mdr1mRNA的表达,pshRNA -mdr1联合阿霉素明显抑制SKOV3 /ADM细胞的增殖。结论:靶向于mdr1的pshRNA联合阿霉素能显著抑制SKOV3 /ADM的增殖。

急性髓系白血病患者体外药敏试验和多药耐药基因mdrl的表达及其临床意义

多药耐药(MDR)是急性白血病化疗成功的主要障碍之一,其机理涉及诸多因素。建立能够体外准确预测化疗药物敏感性试验方法,在指导急性白血病治疗中具有重要意义。本文研究了42例急性白血病患者体外药敏检测(MTT法)和白血病细胞P-gp)抗原的表达与白血病化疗疗效的关系。结果显示:药敏试验与治疗疗效有相关性,临床总符合率82.9%,阳性符合率78.9％,阴性符合率86.9％。认为P-gp的表达是一个有效的化疗耐药指标,白血病缓解病人P-gp阳性率高于初诊病人,P-gp阳性表达的患者完全缓解率明显低于P-gp阴性患者。

联合检测MDR_1/P-gp、C-erbB-2在乳腺癌中的表达及临床意义

目的 :联合检测乳腺癌患者中MDR1/P gp、及C erbB 2的表达 ,并探讨MDR1/P gp与C erbB 2的相关性。方法 :采用荧光定量RT PCR(FQ RT PCR)法检测 5 7例乳腺癌、2 0例对照组 (包括 10例乳腺良性疾病、10例癌旁正常组织 )中MDR1基因的表达 ,同时采用免疫组化法检测上述标本中P gp及C erbB 2蛋白的表达。 结果 :乳腺癌患者中MDR1基因扩增率及P gp蛋白阳性率分别为 5 0 .88% (2 9/ 5 7)和 4 2 .11% (2 4 / 5 7) ,与正常对照组相比均具有显著性差异 (P <0 .0 1)。MDR1基因扩增率高于P gp蛋白表达 ,二者呈高度相关 ,但并不完全相符 ;乳腺癌中C erbB 2过表达率为 2 8.0 7% (16 / 5 7) ,正常对照组中无C erbB 2蛋白过表达。MDR1/P gp阳性率与C erbB 2过表达呈正相关。结论 :乳腺癌中存在多药耐药基因MDR1及原癌基因C erbB 2的共表达 ,且其表达呈正相关。上述二种基因的表达 ,与乳腺癌的多药耐药有关。

肺癌中MDR基因产物LRP、P-gp、GST-π、TopoⅡ的表达及临床意义

目的:探讨多药耐药(MDR)基因产物LRP、P-gp、GST-π、TopoⅡ在肺癌中的表达及临床相关性。方法:应用单克隆抗体、免疫组化技术S-P法,对70例肺癌标本进行上述4种MDR指标检测。结果:在肺癌组织中LRP、P-gp、GST-π、TopoⅡ表达的阳性率分别为75.7%、70.0%、82.9%、84.3%,其与性别、年龄、部位、临床分期无关(P>0.05);在未分化、小细胞型肺癌中LRP、P-gp、GST-π表达的阳性率明显降低(P<0.05),而TopoⅡ表达的阳性率则升高(P<0.05,低分化型肺癌除外)。结论:LRP、P-gp、GST-π、TopoⅡ在未化疗过的肺癌组织中均有不同程度的高表达,且与肺癌的某些生物学行为有关,联合检测有助于化疗药物的选择及预后的判断。

肺癌患者外周血中MDR1的表达及临床意义

目的检测多药耐药基因-1(MDR1)在肺癌患者外周血中的表达,探讨MDR1的表达水平与肺癌病理类型及临床化疗进程之间的关系。方法应用荧光定量PCR(qRT-PCR)技术,动态监测45例肺癌患者化疗前后外周血中MDR1的表达水平,并与48例健康者进行对照比较。结果肺癌组化疗前MDR1的阳性率28.89%(13/45),明显高于健康对照组2.08%(1/48),差异显著(P<0.05);各种病理类型的肺癌随着化疗次数的增多MDR1的表达均增强;化疗前后各期MDR1的表达程度:非小细胞肺癌(NSCLC,肺鳞癌和肺腺癌)明显高于小细胞肺癌(SCLC),差异具有统计学意义(P<0.05),而肺鳞癌和肺腺癌之间MDR1的表达程度相当,无显著差异,(P>0.05)。结论化疗可诱导各种病理类型肺癌MDR1表达增加;病理类型不同诱导化疗耐药的机制可能不同:NSCLC可能为原发性MDR,SCLC可能为获得性MDR;动态检测肺癌患者外周血中MDR1的表达水平,有利于进行肺癌耐药的监测与评价。

复发转移性乳腺癌mdr-1基因产物P-糖蛋白表达的临床意义

目的 探讨复发转移性乳腺癌mdr 1基因表达产物P 糖蛋白 (P glycoprotein ,P gp)表达及其与含吡喃阿霉素联合方案化疗疗效的关系。方法 应用SABC法检测 4 6例转移性乳腺癌术后组织中P gp表达 ,使用环磷酰胺、吡喃阿霉素和 5 氟尿嘧啶联合方案化疗 ,对比分析P gp表达与疗效的关系。 结果 ① 4 6例患者mdr 1基因表达产物P gp阳性表达率 5 6 .5 % ,肝或肺转移者阳性表达明显高于皮肤或淋巴结转移者 (P =0 .0 4 9)。②可评价疗效的 4 3例患者化疗有效率 5 8.1% ;P gp阴性组疗效 (89.5 % )明显优于P gp阳性组 (30 .0 % ) (P <0 .0 1)。③有肝或肺转移者有效率(4 0 .7% )明显低于皮肤或浅表淋巴结转移者 (87.5 % ) (P <0 .0 5 )。④术后曾接受辅助性CAF或CMF方案化疗者复发转移后化疗疗效 (71.4 %和 37.5 % )无显著性差异 (P =0 .0 5 2 )。结论 mdr 1基因表达产物P

含MDR基因的人乳腺癌MCF 7/pZMDR多药耐药细胞株的构建

目的：肿瘤细胞的多药抗药性（ＭＤＲ）是化疗失败的主要原因之一，Ｐ－糖蛋白高表达是ＭＤＲ的主要机制，逆转ＭＤＲ成为肿瘤治疗亟待解决的问题。目前用于研究抗药性和筛选逆转抗药性药物的模型较少，本实验拟构建多药抗药性细胞株。方法：采用基因工程技术，重组ＭＤＲ１基因ｃＤＮＡ于逆转录病毒载体ｐＺＩＲ－ＮｅｏＳＶ（Ｘ）的克隆位点，并用脂染胺（ｌｉｐｏｆｅｃｔＡＭＩＮＥ）介导的ＤＮＡ转移技术，将其转入包装细胞ＰＡ３１７中，收集含病毒子的培养上清液感染对药物敏感的人乳癌细胞株ＭＣＦ－７，经筛选培养基筛选，ＰＣＲ、免疫组化及阿霉素在细胞内的分布等实验。结果：含ＭＤＲ基因的逆转录病毒载体ｐＺＭＤＲ的构建方法证明是正确的，ＭＤＲ１ｃＤＮＡ已整合在染色体基因组中并表达Ｐ－糖蛋白。

MDR_1基因与ER及PR在乳腺癌中的表达

目的：检测乳腺癌组织中多药耐药基因的表达并探讨其与ER，PR以及预后的关系。方法：采用S－P免疫织化方法，对120倒乳腺癌组织进行P糖蛋白（PgP），ER／PR表达的检测。结果：乳腺癌组织中P糖蛋白阳性表达为33.3％，ER阳性表达51．7％，PR阳性表达37.5％。P糖蛋白与乳腺癌组织类型及ER／PR天关，PgP，ER／PR阳性表达均与乳腺病预后有关（P＜0.01）。结论：PgP，EE／PR三个指标估计乳腺癌预后比单一指标为好。

肿瘤多药耐药(MDR)和抗凋亡之间的关系

肿瘤多药耐药(multidrug resistance,MDR)是肿瘤放化疗治疗失败的重要原因。肿瘤MDR的产生主要与肿瘤细胞高表达ABC超家族外排泵与肿瘤细胞本身所表现的凋亡抑制有关。本文针对肿瘤细胞的MDR与抗凋亡相关信号通路、因子和酶的关系以及它们与ABC超家族转运体的关系作一综述。

MDRI的siRNA干扰口腔Tca8ll3/DDP细胞表达的研究

目的探讨小干扰RNA(small interfering RNA,si RNA)对口腔鳞癌多药耐药基因mdr1(MDRI)及其表达产物P-糖蛋白(permeability-glyco-protein,P-gp)的干扰作用。方法体外构建针对MDR1的小干扰RNA,将其转染至人舌癌耐药细胞系Tca8113/DDP,采用RT-PCR法检测转染前后MDR1 m RNA的表达;采用免疫细胞化学技术比较转染前后P-gp的表达;采用MTT法检测转染前后肿瘤耐药细胞对顺铂的敏感性。结果 Tca8113/DDP细胞经MDR1-si RNA转染后48 h的转染率达最高,为71.3%;转染后mdr1 m RNA表达较对照组显著降低,降低率为68.32%,转染48 h后P-gp的表达较对照组明显降低;si RNA可显著提高Tca8113/DDP细胞对DDP的敏感性,逆转其耐药性,耐药倍数为2.05。结论 si RNA可以明显干扰口腔鳞癌MDR1及相应蛋白P-gp的表达。

Progress in the studies on the molecular mechanisms associated with multidrug resistance in cancers

Chemotherapy is one of the important methods to treat cancer,and the emergence of multidrug resistance(MDR)is one major cause for the failure of cancer chemotherapy.Almost all anti-tumor drugs develop drug resistance over a period of time of application in cancer patients,reducing their effects on killing cancer cells.Chemoresistance can lead to a rapid recurrence of cancers and ultimately patient death.MDR may be induced by multiple mechanisms,which are associated with a complex process of multiple genes,factors,pathways,and multiple steps,and today the MDR-associated mechanisms are largely unknown.In this paper,from the aspects of protein–protein interactions,alternative splicing(AS)in pre-mRNA,non-coding RNA(ncRNA)mediation,genome mutations,variance in cell functions,and influence from the tumor microenvironment,we summarize the molecular mechanisms associated with MDR in cancers.In the end,prospects for the exploration of antitumor drugs that can reverse MDR are briefly discussed from the angle of drug systems with improved targeting properties,biocompatibility,availability,and other advantages.

Reversal of drug resistance of multidrug-resistant human lung cancer cells by an MDR1 ribozyme

MALIGNANT tumor is very harmful to human health, and the mortality is very high. About 50% of the patients with malignancy can be operated on, and the other 50% patients have to be treated with chemotherapy. Because tumors are mostly chemoresistant, chemotherapy for these patients often has no effect. The overexpression of MDR1 gene is very common in hu man malignant tumors, about 50% in previously untreated patients and more than 50% in previously treated patients for whom the tumor is resistant to the previous sensitive

KB细胞耐药株的建立及其耐药机制的探讨

用对长春新碱（ＶＣＲ）敏感的ＫＢ细胞为亲本，通过诱变剂甲基磺酸乙酯刺激，然后在培养液中加入浓度递增的ＣＶＲ，得到耐药细胞株ＫＢＶ２００。此细胞株对ＶＣＲ的耐受程度约为ＫＢ细胞的１７５倍。对其它抗肿瘤药物如紫杉醇、秋水仙碱和阿霉素等也有不同程度的交叉耐药性。进一步研究表明，ＫＢＶ２００对３Ｈ－ＶＣＲ的蓄积明显减少，且耐药基因（ｍｄｒ１）表达增加。钙通道阻滞剂维拉帕米（Ｖｅｒ）可增加ＫＢＶ２００对３Ｈ－ＶＣＲ的蓄积和对ＶＣＲ的敏感性。这些结果提示，ＫＢＶ２００耐药的机制可能是由于ｍｄｒ１基因表达增加，产生过量的ｐ－糖蛋白，使药物外排增多所致。

P-糖蛋白与ER、PR在乳腺癌中的表达及意义

目的：探讨耐药基因P－糖蛋白（P－gP）在乳腺癌的表达，以及与组织学类型、淋巴结转移、ER和PR之间的相互关系，为乳腺癌的优化化疗，预测预后提供有用的指标的方法：应用免疫组化检测37例乳腺癌和10例非癌病变的P－gP、ER、PR。结果：ER、PR的阳性率分别为43．24％和40．54％，P－gP的表达率为70％，27例P－gP阳性病例中有50％左右ER和PR同时表达。结论：乳腺癌是耐药基因P－gP高表达肿瘤，P－gP与组织学类型、淋巴结转移之间无相互关系，与ER、PR有关，提示乳腺癌的化疗若辅于性激素治疗，疗效可能更好。

超声波体内逆转肿瘤多药耐药基因表达的实验研究

目的:探讨超声波体内逆转肿瘤多药耐药的有效性及其逆转机制。方法:70只HepG2/ADM移植瘤裸鼠随机分成对照组(10只),ADM组(20只),超声组(20只),ADM联合超声组(20只),治疗28天后收集标本。应用RT-PCR法和免疫组织化学法检测多药耐药相关基因和蛋白(MDR1,MRP和LRP)表达。结果:超声治疗组能显著逆转裸鼠HepG2/ADM移植瘤多药耐药基因的表达。免疫组化结果显示,超声治疗组和ADM联合超声组的P-gp,MRP阳性表达显著降低;与对照组相比,在超声治疗组和ADM联合超声治疗组P-gp,MRP水平明显降低。RT-PCR结果显示,超声组和ADM联合超声组能明显降低HepG2/ADM移植瘤细胞MDR1 mRNA和MRP mRNA的表达。结论:多种机制参与超声波逆转肿瘤多药耐药,超声波通过下调MDR1和MRP mRNA和蛋白表达水平,增加细胞内药物浓度等途径逆转肿瘤多药耐药。

麂属(Muntiacus)动物线粒体12SrRNA、细胞色素b基因和多药耐药基因序列分析及其分子进化关系

对麂属 (Muntiacus)中的 3种动物 :赤麂 (M .muntjak) (2n =6♀ ,7♂ )、小麂 (M .reevesi) (2n =4 6 )、黑麂 (M .crinifrons) (2n =8♀ ,9♂ )线粒体DNA 12SrRNA和细胞色素b基因 784bp左右的片段和核基因———多药耐药基因(multidrugresistance ,MDR1)的 72 8bp左右的片段进行了序列分析 ,并根据序列信息建立了分子系统树 ,同时探讨了这 3种动物的起源。