EXPRESSION AND CLINICAL SIGNIFICANCE OF MULTIDRUG RESISTANCE GENE AND MULTIDRUG RESISTANCE-ASSOCIATEDPROTEIN GENE IN ACUTE LEUKEMIA

Objective: To evaluate the expression and clinical significance of multidrug resistance gene (mdr1) and multidrug resistance-associated protein (MRP) gene in acute leukemia. Methods: The expression of mdr1 and MRP assay in 55 patients with acute leukemia (AL) by reverse transcription polymerase chain reaction (RT-PCR). Results: The mdr1 and MRP gene expression levels in the relapsed AL and the blastic plastic phases of CML were significantly higher than those in the newly diagnostic AL and controls. The mdr1 and MRP gene expression levels in the clinical drug-resistant group were significantly higher than those in the non-drug-resistant group. The complete remission (CR) rate in patients with high mdr1 expression (14.3%) was significantly lower than that with low mdr1 expression (57.5%); similarly the CR rate in patients with high MRP level was also lower than that with low MRP level. Using both high expression of mdr1 and MRP gene as the indicator for evaluating multidrug resistance (MDR), the positive predictive value and accuracy increased in comparison with single gene high expression. Conclusion: Elevated level of mdr1 or MRP gene expression might be unfavorable prognostic factors for AL patient and may be used as an important index for predicting drug-resistance and relapse in AL patient. Measuring both mdr1 and MRP gene expression would increase accuracy and sensibility of evaluating MDR in acute leukemia.

EXPRESSION OF MULTIDRUG RESISTANCE-ASSOCIATED PROTEIN (MRP) AND ITS RELATIONSHIP WITH CLINICOPATHOLOGICAL FACTORS IN NON-SMALL CELL LUNG CANCER

Objective: To investigate the relationship between the expression of multidrug resistance-associated protein (MRP) and clinicopathological factors and prognosis. Methods: The expression of MRP in 62 cases with non-small cell lung cancer (NSCLC) was detected using immunohistochemistry method. The expression of MRP in 30 cases of NSCLC and corresponding normal lung tissues were detected using immunohistochemistry and Western Blot. Results: this study of tumor tissues confirmed the plasma membrane and/or cytoplasm locations of MRP. There was apparent difference between normal lung tissues and NSCLC in MRP. The survival analysis of 62 NSCLC showed that the mean survival time of the patients with negative MRP expression was 69.8117.41 months and that of patients with positive MRP expression, 25.384.46 months. Log-rank test suggested that the difference between them was significant (P=0.0156). It was also found that in squamous cell lung cancer the statistically significant difference between the mean survival time of patients with positive MRP expression and those with negative MRP expression (P=0.0153). Multivariate Cox model analysis suggested that the survival time was significantly related to expression of MRP (P=0.035) and lymphatic metastasis (P=0.038). Conclusion: MRP expression in NSCLC is significantly higher compared with normal lung tissues. The mean survival time of patients with negative MRP was relative longer and expression of MRP was an independent factor for prognosis.

Expression and significance of multi-drug resistance-associated protein 3 in different tumor cell lines

Objective To investigate the expression and meaning of MRP3 in different tumor cells. MethodsThe monoclonal antibody against MRP3 was used to identify the expression of MRP3 by flow cytometer in seven tumor cells and human embryo kidney cell lines 293T.And RT-PCR was used to detect the mRNA of MRP3 in eight cell lines. ResultsThe mRNA of MRP3 was expressed in three pancreatic carcinoma cell lines.MRP3 protein was observed in BxPC-3 and AsPC-1 cells. ConclusionMRP3 may express in different tumor in tissue-specific manner.BxPC-3 and AsPC-1 may serve as cellular models for in vitro studies on multidrug resistance of pancreatic carcinoma.

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.

ATP结合盒亚家族B成员4(ABCB4)基因突变相关性肝硬化合并胆囊结石1例报告

ATP结合盒亚家族B成员4(ABCB4)基因突变疾病谱涉及进行性家族性肝内胆汁淤积3型、胆石症、妊娠期肝内胆汁淤积症、门静脉高压、肝硬化,甚至原发性肝脏、胆道恶性肿瘤等多种疾病。本院肝胆内科收治1例青年男性患者,入院初步诊断为胆囊结石,计划腹腔镜胆囊切除术,术前检查发现该患者肝功能异常、肝硬化、脾大、食管静脉轻度曲张,后进一步行二代测序明确诊断为ABCB4基因突变相关性肝硬化合并胆囊结石,给予熊去氧胆酸胶囊利胆治疗后,肝功能逐渐恢复正常。

Effects of Hypoxia on Expression of P-gp and Mutltidrug Resistance Protein in Human Lung Adenocarcinoma A549 Cell Line

To study the effects of hypoxia on the expression of P-gp and mutltidrug resistance protein in human lung adenocarcinoma A549 cell line, and to explore the probable mechanism of hypoxia in tumor cell of MDR. The expression of hypoxia inducible factor-1α, P-gp and mutltidrug resistance protein was immunohistochemically detected by culturing human lung adenocarcinoma A549 cell under hypoxia (2 % O_2) for 24 h. After interaction with adriamycin or cisplatin under hypoxia (2 % O_2) for 24 h, the cell survival rate was detected by MTT. Our results showed that the expression of hypoxia inducible factor-1α, P-gp and mutltidrug resistance protein under hypoxia were higher than the expression under normoxia, and correlations between the expression of HIF-1α and P-gp or multidrug resistance-associated protein was observed (P<0.05). The resistance of adriamycin of A549 cell was enhanced under hypoxia. It is concluded that the resistance of tumor chemotherapy is enhanced in hypoxia. The expression of HIF-1α is obviously correlated with the expression of P-gp and mutltidrug resistance protein.

Bioinformatics analysis of structure and function in the MRP gene family and its expression in response to various drugs in Bursaphelenchus xylophilus

Genes homologous to members of the MRP gene family in Caenorhabditis elegans are important in drug resistance.To further explore the molecular mechanism of drug resistance in pine wood nematode(Bursaphelenchus xylophilus),we used bioinformatics approaches to analyze genomic data for B.xylophilus and identified Bx-MRP genes.We predicted the structure and function of the genes and encoded proteins.Using bioinformatics programs to predict and analyze various properties of the predicted proteins,including hydrophobicity,transmembrane regions,phosphorylation sites,and topologically isomeric structures,of these Bx-MRP genes,we determined that they function in transmembrane transport.From the results of RT-qPCR,the Bx-MRP family members confer significant differential resistance to different drug treatments.After treatment with different concentrations of emamectin benzoate,avermectin and matrine,the expression of each gene increased with increasing drug concentrations,indicating that the family members play a positive role in the regulation of multidrug resistance.

EXPRESSION OF MDRII MRP AND LRP GENES IN GASTRIC CARCINOMA AND THEIR CLINICAL SIGNIFICANCE

Objective: To explore the expression of mdrl,multidrug resistance-associated protein (MRP) and lungresistance protein (LRP) genes in human gastric cancerand their clinical significance. Methods: The mdrlmRNA was assayed by RT-PCR, the MRP and LRPwere detected by flow cytometry. Results: The positiverate of mdrl mRNA was 44.4% (12/27), and the meanMRP and LRP expression were independent uponpatient histologic type, nodal involvement, and TNMstage. The mdrl mRNA expression in patients withserosa invasion was 30.0% (6120), much lower than thatwithout serosa invasion (85.7%). Conclusion: Themultidrug resistance cells are present in primary gastriccarcinomas prior to chemotherapy, and analysis of mdrlgene, MRP, LRP may have guiding significance in thetreatment of gastric carcinoma.

Effect of Histone Deacetylase Inhibition on the Expression of Multidrug Resistance-associated Protein 2 in a Human Placental Trophoblast Cell Line

Background： Placental multidrug resistance-associated protein 2 （MRP2）, encoded by ABCC2 gene in human, plays a significant role in regulating drugs＇ transplacental transfer rates. Studies o11 placental MRP2 regulation could provide more therapeutic targets for individualized and safe pharmacotherapy during pregnancy. Currently, the roles of epigenetic mechanisms in regulating placental drug transporters are still unclear. This study aimed to investigate the effect of histone deacetylases （HDACs） inhibition on MRP2 expression in the placental trophoblast cell line and to explore whether HDAC 1/2/3 are preliminarily involved in this process. Methods： The human choriocarcinoma-derived trophoblast cell line （Bewo cells） was treated with the HDAC inhibitors-trichostatin A （TSA） at different concentration gradients of 0.5, 1.0, 3.0, and 5.0 μmol/L. Cells were harvested after 24 and 48 h treatment. Small interfering RNA （siRNA） specific for HDACI/HDAC2/HDAC3 or control siRNA was transfected into cells. Total HDAC activity was detected by colorimetric assay kits. HDAC 1/2/3/ABCC2 messenger RNA （mRNA） and protein expressions were determined by real-time quantitative polymerase chain reaction and Western-blot analysis, respectively. Immunofluorescence for MRP2 protein expression was visualized and assessed using an immunofluorescence microscopy and ImageJ software, respectively. Results： TSA could inhibit total HDAC activity and HDAC 1/2/3 expression in company with increase ofM RP2 expression in Bewo cells. Reduction of HDAC 1 protein level was noted after 24 h of TSA incubation at 1.0, 3.0, and 5.0 μmol/L （vs. vehicle group, all P 〈 0.001 ）, accompanied with dose-dependent induction of MRP2 expression （P = 0.045 for 1.0 μmol/L, P = 0.001 for 3.0 μmol/L, and P 〈 0.001 for 5.0 μmol/L）, whereas no significant diferences in MRP2 expression were noted after HDAC2/3 silencing. Fluorescent micrograph images of MRP2 protein were expressed on the cell membrane. The fluorescent intensities of MRP2 in the control, HDAC2, and HDAC3 siRNA-transfected cells weir week, and no significant differences were noticed among these three groups （all P 〉 0.05）. However, MRP2 expression was remarkably elevated in H DAC1 siRNA-transfected cells, which displayed an almost 3.19-fold changes in comparison with the control siRNA-transfected cells （P 〈 0.001 ）. Conclusions： HDACs inhibition could up-regulate placental MRP2 expression in ritzy, and HDAC 1 was probably to be involved in this process.

EFFECTS OF NEOADJUVANT CHEMOTHERAPY ON MDR1 AND MRP GENE EXPRESSION IN PRIMARY BREAST CANCER

Objective: To investigate the effects of neoadjuvant chemotherapy on the expression of drug resistance genes, multidrug resistance-1 (MDR1) and multidrug resistance-associated protein (MRP), in patients with primary breast cancer. Methods: MDR1 and MRP expression were detected by semi-quantitative RT-PCR in 20 patients with primary breast cancer, before and after chemotherapy. Results: Before chemotherapy, MDR1 and MRP expression can be detected in 15 cases (75%) and 18 cases (90%) respectively. After chemotherapy, expression of MDR1 is not significantly different from that before chemotherapy, but expression of MRP is significantly different from that before chemotherapy. Conclusion: Expression of drug resistance gene MRP, but not MDR1, is enhanced in patients with primary breast cancer submitted to neoadjuvant chemotherapy.

A549肺腺癌多细胞球体药敏实验、Mdr1、MRP表达以及^(99m)Tc-MIBI摄取研究

目的探讨A549肺腺癌多细胞球体的多药耐药基因(mdr1)和多药耐药相关蛋白(MRP)基因表达,甲氧基异丁基异腈(MIBI)摄取结果能否预测化疗效果。方法①血浆高峰浓度的化疗药物顺铂(DDP)、长春花碱酰胺(VDS)、氟尿嘧啶(5-氟尿嘧啶,5-FU)、羟喜树碱(HCP)、丝裂霉素(MMC)、多柔比星(阿霉素,ADM)分别进行药物敏感性实验。②单层贴壁细胞培养。96孔板1个,每组4孔,2×104细胞/孔。③MTT检测观察疗效。细胞加化疗药后培养48h,然后加MTT5mg/mL,每孔20μL,4h后用酶标仪(490nm)测量吸光度值。④RT-PCR检测A549细胞和MCF-7耐药株的mdr1和MRP表达,β2-MG作内参照。⑤96孔板内每孔一个球体,每孔掺入99mTc-MIBI9.25×104Bq(2.5μCi),分别于60和120min结束掺入并测量γ计数。结果①A549细胞药敏实验对DDP不敏感,对MMC、VDS、ADM、5-FU、HCP敏感。②MCF-7长春新碱耐药株(MCF-7/VCR)对DDP、VDS不敏感,对MMC、ADM、5-FU和HCP较敏感。③A549细胞及球体的Mdr1/β2-MG为0,MRP/β2-MG分别为0.76和0.62;MCF-7耐药细胞的mdr1/β2-MG和MRP/β2-MG分别为35和4.36。④A549多细胞球体对99mTc-MIBI120min的摄取值高于60min摄取值(P<0.05)。结论A549多细胞球体的mdr1和MRP表达水平较低以及MIBI摄取阳性提示无多药耐药性产生,与化疗药物敏感性检测结果基本一致。A549细胞对DDP耐药说明除mdr1和MRP之外,还存在与转运蛋白间接相关的其他耐药机制。

大肠埃希菌gyrA、parC和marOR基因突变与喹诺酮耐药的相关性

目的:研究大肠埃希菌gyrA、parC和marOR基因突变与喹诺酮类耐药的相关性。方法:采用微量稀释法进行常规药敏试验,筛选3株萘啶酸敏感大肠埃希菌和37株萘啶酸耐药大肠埃希菌株;PCR扩增大肠埃希菌喹诺酮耐药决定区(QRDR)相关gyrA、parC基因,进行聚合酶链反应-单链构象多态性(PCR-SSCP)分析,同时PCR扩增marOR基因;在耐药株选取部分菌株对gyrA、parC及marOR基因进行测序,检测其突变情况,其结果与体外药敏试验结果进行比较,研究其相关性。结果:37株耐药株均出现gyrA基因突变,但对环丙沙星低耐株最低抑菌浓度(MIC)=2mg/L只出现gyrA单位点突变,而parC基因未发生突变;环丙沙星高耐株(MIC=64mg/L)gyrA基因出现3个位点突变,parC基因出现单位点突变;在环丙沙星高耐株(MIC=256mg/L),并伴有其他类抗菌药物的多重耐药时,除了出现gyrA和parC基因双位点突变,同时检测到marOR基因的多位点突变。结论:gyrA和parC基因突变在大肠埃希菌对喹诺酮耐药中起着重要作用,gyrA和parC基因突变的程度与大肠埃希菌耐药水平有关,marOR基因多位点突变在多重耐药机制中具有一定的作用。

多药耐药相关蛋白基因、肺耐药蛋白基因在肝细胞癌中的表达及临床意义

目的 研究多药耐药相关蛋白基因 (MRP)和肺耐药蛋白基因 (LRP)在肝细胞癌 (HCC)中的表达及其与临床的关系。方法 采用SP免疫组化和PCR技术检测 5 4例HCC和 2 4例癌旁组织及 1 2 例肝炎后肝硬化组织中的两种基因表达。结果 MRP和LRP在 3种组织中均有表达,HCC组织中其基因表达显著高于其他组织 (P< 0. 0 5 )。HCC中两种基因表达呈正相关 (r= 0. 3 1 2, P <0. 0 5; r= 0. 3 2 8, P< 0. 0 5 );其表达与HCC的分化程度有关 (P< 0. 0 5 )。并且其表达阳性组患者化疗后AFP有效率和平均生存期分别高于和长于阴性组 (P< 0. 0 5 ),但LRP与平均生存期无关 (P> 0. 0 5 )。结论 HCC多药耐药 (MDR)与两种基因表达有关,起源于内源性耐药;检测其表达对预测化疗耐药具有指导意义;MRP可能与预后有关。

非M3型急性白血病患者中MUC1基因和MDR1基因表达及其与临床疗效的关系

背景与目的:MUC1基因在胃癌、卵巢癌、多发性骨髓瘤、恶性淋巴瘤等肿瘤中有表达,在急性白血病患者中有较高的表达。但MUC1基因和多药耐药基因(MDR1)相互关系以及两者的表达与急性白血病治疗效果的关系尚有待探讨。本研究拟探讨MUC1基因与MDR1基因表达及其与非M3型急性白血病患者治疗效果的关系。方法:应用逆转录鄄聚合酶链反应(RT鄄PCR)法检测34例初治非M3型急性白血病患者MUC1和MDR1的表达,并观察两种基因表达及其与临床疗效的关系。结果:34例初治非M3型急性白血病患者中MUC1基因阳性率为50%,MDR1基因阳性率为29.4%。MUC1基因阳性患者的MDR1阳性率为52.9%,明显高于MUC1阴性者的5.9%(P=0.003)。MUC1基因阴性者完全缓解(CR)率达94.1%,阳性患者CR率52.9%,两组有显著性差异(P<0.05);MDR1基因阴性者CR率为91.7%,明显高于阳性患者的50.0%(P<0.05)。MUC1基因和MDR1基因均阳性者CR率为55.6%,MUC1基因和MDR1基因均阴性者16例,全部获得CR。结论:非M3型急性白血病MUC1基因阳性者MDR1基因表达率较高,MUC1基因及MDR1基因均为阴性者治疗缓解率高。提示联合检测MUC1基因和MDR1基因对判断初治非M3型急性白血病的疗效有良好的预测作用,可作为临床判断疗效的一项有意义的指标。

mrp反义RNA逆转胃癌细胞系SGC7901对VCR的耐受性

目的 :探讨以多药耐药相关蛋白 (MRP)作为靶分子进行胃癌多药耐药基因治疗的可行性。方法 :采用已构建成功的mrp反义RNA真核载体pcDNA Amrp转染胃癌细胞系SGC790 1,用G418抗性筛选出稳定细胞克隆 ,命名为M SGC790 1;用32 P标记的寡核苷酸探针打点杂交检测M SGC790 1细胞中mrpmRNA表达的变化 ;从细胞生长曲线中 ,观察M SGC790 1细胞生长速度的变化 ;经 0 .0 0 5 μg/ml的长春新碱 (VCR)处理 1月后 ,行流式细胞术检测M SGC790 1细胞周期的改变 ;同时 ,行MTT法检测M SGC790 1对VCR的IC50 值 ;最后 ,行Habit法检测M SGC790 1中谷胱苷肽S 转移酶 (GST)活性。结果 :①M SGC790 1细胞的mrpmRNA表达的阳性信号明显较对照组弱。②M SGC790 1细胞生长速度与对照组无明显差异 (P >0 .0 5 )。③M SGC790 1生长明显阻滞于S期 (P <0 .0 5 )。④M SGC790 1对VCR的IC50 值显著降低 (P <0 .0 5 )。⑤M SGC790 1中GST活性与对照组相比无明显差异 (P >0 .0 5 )。结论

携带反义多药耐药相关蛋白的重组腺病毒载体的构建

目的 构建携带反义多药耐药相关蛋白 (MRP)的重组腺病毒载体以用于肝癌耐药的基因治疗研究。方法 将 MRP基因片段反向克隆到腺病毒载体质粒 p Ad Track- CMV上 ,与骨架质粒在大肠杆菌 BJ5 183胞内进行同源重组 ,经 2 93细胞包装、扩增后得到携带反义 MRP的重组腺病毒 Ad Easy- GFP- ASmrp。结果 成功地构建了携带反义 MRP的重组腺病毒载体系统 ,经测定病毒滴度可达 2 .5× 10 9。结论 构建的重组腺病毒 Ad Easy- GFP-ASm rp可望有效地将反义 MRP导入人肝癌耐药细胞株 。

黄芩苷对白血病细胞耐药株逆转耐药效果及机制研究

目的:观察黄芩苷对白血病耐药株细胞的耐药逆转作用,并初步探讨其可能的机制。方法:MTT法检测阿霉素及黄芩苷对白血病亲本细胞及耐药株细胞的抑制率,通过计算阿霉素对耐药株细胞及亲本细胞的半数抑制浓度(IC50)评价耐药倍数,通过阿霉素与黄芩苷联用的IC50评价黄芩苷的逆转作用,流式细胞计数法检测黄芩苷作用后对耐药细胞内阿霉素药物蓄积的影响,RT-PCR检测黄芩苷对耐药细胞中多药耐药相关基因MDR1、MRP1以及LRP1表达的影响。结果:耐药细胞株的耐药倍数为17.384倍,黄芩苷10μg/ml和20μg/ml对白血病耐药株的逆转倍数分别为4.230和7.812,相对逆转率分别为0.81和0.93,黄芩苷作用后耐药株细胞内阿霉素蓄积明显增加,MDR1基因表达显著下降。结论:黄芩苷对白血病耐药细胞株具有显著的逆转作用,其机制可能与下调了细胞内的MDR1基因表达进而抑制P糖蛋白对阿霉素的泵出有关。

云南省现场恶性疟原虫3个抗药性基因点突变特征

目的 研究云南省现场恶性疟原虫 3个与抗疟药抗性有关的dhfr、pfmdr1和pfcrt的点突变特征 ,为抗药性恶性疟原虫的分子生物学研究提供背景资料。 方法 应用特异性套式多聚酶链反应 (PCR)和限制性酶切片段长度分析 (RFLP)方法 ,检测恶性疟现症病人干滤纸血样的恶性疟原虫 3个抗药性基因点突变情况。 结果 恶性疟原虫dhfr基因内 16,5 1,10 8和 164位氨基酸有不同程度的突变 ,突变型比例高 ,以Asn -10 8和Ⅰle -5 1为甚 ,频度分别为94 3 %和 81 3 %。野生型 ( 3D7型 )Ser -10 8出现较低频率 8 6% ,而AIa -16出现频率较高 68 6% ;pfcrt基因的 76位点由K突变为T ,突变型 (含混合 )占 96 7% ;野生型仅占 3 4% ;pfmdr1基因 86位点由Asn突变为Tyr ,突变型占 3 4 % ;野生型点 48 7% ;混合型占 16 7%。未发现 12 46位点突变的存在。 结论 云南现场恶性疟原虫与抗疟药抗性有关的3个pfdhfr、pfmdr1和pfcrt基因有较广泛的点突变特征。

人乳腺癌MRP基因表达与临床病理参数的关系

目的 研究多药耐受相关蛋白基因 (MRP)在人乳腺癌中的表达与临床病理参数的关系。方法 采用免疫组化技术检测 6 2例初发乳腺癌组织标本MRP表达 ,13例癌旁正常乳腺组织和 8例乳腺良性肿瘤组织作为对照。结果 三种组织阳性率分别为 :乳腺癌 72 6 % ,癌旁正常乳腺组织2 3 1% ,乳腺良性肿瘤 18 2 %。癌组织与其它两种组织相比 ,差异具有显著性 (P <0 0 5 )。乳腺癌组织MRP表达水平与提示乳腺癌疾病发展和预后的临床病理参数 ,如年龄、原发灶大小、淋巴结转移数、病理学类型和组织学分级无关 (P>0 0 5 )。结论 多药耐受表型是与乳腺癌恶性表型同时发生的一种内在本质特征 ,其表达程度不受疾病发展的影响。S P免疫组织化学方法检测临床乳腺标本具有灵敏度高、相对定量。

MRP基因与肿瘤的多药耐药性

在人肿瘤非典型性多药耐药机制的研究中发现了一个新的基因———多药耐药相关蛋白基因(MRP) .该基因位于人 1 6号染色体P1 3∶3,编码 1 531个氨基酸 .其产物为多药耐药相关蛋白(MRP) ,分子质量 1 90ku ,故又名 p1 90 .MRP属ABC超家族成员 ,主要分布在细胞的质膜上 .MRP的功能可能是在能量依赖的外排系统中发挥作用 .除了一些肿瘤细胞系外 ,MRP基因的高表达还见于一些血液系肿瘤及乳腺癌等 .MRP基因的高表达还可能与某些肿瘤的复发和预后有关 .