不同性激素对P-糖蛋白表达水平及甲磺酸伊马替尼转运的影响

目的：探讨在ABCB1（1199G/A）重组细胞模型中不同性激素对P-糖蛋白（P-gp）表达水平及甲磺酸伊马替尼转运的影响。方法：将构建的ABCB1_1199G/wt和ABCB1_1199A/mut重组质粒稳定转染入HEK293细胞中,采用RT-PCR和Western Blot分别检测不同性激素对P-gp mRNA和蛋白的表达水平;采用HPLC检测性激素对甲磺酸伊马替尼累积量的影响。结果：浓度梯度的性激素（雌酮、雌三醇雌二酮、黄体酮和睾酮）刺激ABCB1_1199G/wt 和ABCB1_1199A/mut重组细胞后,雌酮和雌三醇能刺激P-gp mRNA和蛋白表达水平,且雌三醇上调ABCB1_1199A/mut mRNA的表达水平显著高于ABCB1_1199G/wt;雌酮和雌三醇可降低甲磺酸伊马替尼在细胞内的累积量,产生对伊马替尼的耐药性。结论：雌酮和雌三醇增加了细胞内P-gp的表达,并促进P-gp介导甲磺酸伊马替尼的转运能力。     

ABCB1（1199G/A）基因多态性对甲磺酸伊马替尼转运的分子机制

摘 要 目的：探讨P 糖蛋白（P-gp）活性和所介导的甲磺酸伊马替尼胞内累积量及药物跨膜渗透性的影响。 方法: 将构建的ABCB1 1199G/wt和1199A/mut重组质粒分别转染HEK293细胞,利用RT-PCR法考察细胞中P-gp的mRNA表达水平。CCK-8法检测药物对细胞的毒性,高效液相色谱法（HPLC）检测细胞中药物浓度和胞内累积量,跨膜电阻实验考察药物跨膜渗透率,评价P-gp活性对药物转运的作用。结果: 细胞毒性实验表明,转染细胞内的药物浓度均低于对照组,证明P-gp具有介导药物转出胞外的作用。HPLC和跨膜电阻实验表明,与野生型ABCB1(1199G)细胞相比,突变型ABCB1(1199A)细胞抗甲磺酸伊马替尼的作用更强,P-gp对介导甲磺酸伊马替尼外排转运的作用较强且药物的跨膜渗透性也相应较强。结论:实验表明ABCB1（1199G/A）位点突变导致其编码蛋白P-gp活性改变,该位点多态性会导致甲磺酸伊马替尼清除率增加,抑制了药物在靶细胞中有效药物浓度,因此临床上应对ABCB1基因进行分型,指导甲磺酸伊马替尼的个体化用药。     

ABCB1(G1199A)基因稳定转染HEK293细胞株的建立

目的:将ABCB1(G1199A)突变型和野生型基因分别转入HEK293细胞,建立P-糖蛋白稳定表达细胞株。方法:以野生型ABCB1基因的cDNA为模板质粒,采用PCR点突变的方法合成突变的ABCB1(1199A)基因;在慢病毒的介导下,将实验室构建的pLVX-ABCB1-PGK-Puro和pLVX-ABCB1-mut-PGK-Puro重组质粒转染HEK293细胞,经嘌呤霉素筛选稳定表达的细胞;通过流式细胞术检测P-糖蛋白的表达、RT-PCR检测ABCB1基因的转录水平、CCK-8方法测定外源基因对HEK293细胞增殖的影响。结果:流式细胞术证实P-糖蛋白在HEK193细胞中稳定过表达,RT-PCR确定转染细胞中存在ABCB1(G1199A)基因mRNA的过表达,成果获得ABCB1(G1199A)野生型和突变型基因的稳定表达细胞株。结论:成功建立两种ABCB1(G1199A)稳定表达的HEK293细胞株,为该酶的功能研究奠定了基础。     

ABCB1基因多态性对多西他赛药动学和药效学影响的研究进展

由于肿瘤的发生是一个复杂的生物学过程,再加上肿瘤患者存在的个体差异,药物转运蛋白的基因多态性导致的化疗疗效和不良反应显著差异越来越受到人们的重视。多西他赛作为多种肿瘤的有效治疗药物,其存在的疗效、不良反应差异与基因多态性的关系也日益受到人们的关注,其中研究最多的主要是ABCB1的基因多态性。我们就ABCB1的基因多态性情况,ABCB1基因多态性对多西他赛药动学的影响,ABCB1基因多态性与多西他赛疗效、不良反应的相关性几个方面进行综述,以期为临床更合理地运用多西他赛,发挥更有效地抗肿瘤作用并减少不良反应提供参考。     

ABCB1基因多态性对肾移植受者环孢素血浓度的影响

目的:研究肾移植术后患者ABCB1基因多态性对环孢素（CsA）血浓度的影响。方法:采用PCR-RFLP（聚合酶链反应-限制性片段长度多态性）方法对339名服用CsA的肾移植患者进行ABCB1基因1236C>T、2677G>T/A和3435C>T多态性检测,荧光偏振免疫法检测肾移植患者CsA血浓度。结果:在339名肾移植患者中,ABCB1基因1236C>T、2677G>T/A和3435C>T突变等位基因频率分别为64.25%、51.54%和35.75%。ABCB1 1236C>T基因多态性检测显示,在移植术后1年,CC基因型个体的CsA血谷浓度明显高于CT和TT基因型个体（P<0.05）。2677G>T/A基因多态性检测提示,在移植术后7d,杂合子GA+GT基因型携带者的C₀高于GG和AA+TT+AT基因型携带者（P<0.05）。3435C>T基因多态性检测表明:在移植术后3个月,突变纯合子TT基因型携带者的C₀低于CC和CT基因型携带者（P<0.05）。其余各时间点,上述3种基因多态性对CsA血谷浓度无明显影响（P>0.05）。结论:ABCB1基因1236C>T、2677G>T/A和3435C>T多态性对极少数时间点的CsA浓度有影响,但对绝大多数时间点的环孢素浓度无影响。     

ABCB1基因多态性与五酯胶囊对他克莫司增效作用的相关性研究

摘 要 目的：研究五酯胶囊对他克莫司增效作用与 ABCB1基因多态性的相关性研究。方法: 通过聚合酶链反应 限制性片段长度多态性(PCR RFLP)方法测定ABCB1 1236C>T(rs1128503)、ABCB1 2677G>T/A(rs2032582)和ABCB1 3435C>T(rs1045642)基因型,使用化学发光微粒子免疫分析技术(CMIA)检测他克莫司C0。采用协方差分析考察不同组别患者他克莫司C0/D的差异。结果: 无论是单独使用他克莫司,还是他克莫司与五酯胶囊合用,ABCB1 1236C>T、ABCB1 2677G>T/A、ABCB1 3435C>T 不同基因型及单倍型组的他克莫司C0/D均无显著差异（P>0.05）。结论: 五酯胶囊对他克莫司的增效作用与ABCB1 1236C>T、ABCB1 2677G>T/A、ABCB1 3435C>T基因多态性无关。     

6种药物对有机阴离子转运多肽OATP1B1及其基因多态性A388G、T521C转运作用的影响

目的 研究6种药物对有机阴离子转运多肽OATP1B1及其基因多态性A388G、T521C转运作用的影响。方法 体外培养稳定高表达OATP1B1和OATP1B1基因多态性A388G、T521C的人胚肾细胞（HEK293）株,高表达空白载体（Mock）的HEK293细胞为空白对照,实时荧光定量PCR（qRT-PCR）法检测各转运体细胞中mRNA表达;放射性标记化合物³Hestrone sulfate作为转运底物、利福平作为阳性抑制剂验证各高表达细胞的转运活性;测定30 μmol·L^-1的达比加群、辛伐他汀、替格瑞洛、卡培他滨、多西他赛、依那普利对各细胞³H-estrone sulfate摄入活性的抑制作用,并依据抑制试验结果,进一步测定辛伐他汀、替格瑞洛、多西他赛对转运体细胞的半数抑制浓度（IC₅₀）。结果 HEK293细胞内导入的各种转运体基因都呈现良好的复制表达;OATP1B1、OATP1B1/A388G、OATP1B1/T521C对底物³H-estrone sulfate（5 μmol·L^-1）的转运活性分别为Mock细胞的39、49和48倍,30 μmol·L^-1利福平添加后,可将细胞的转运活性抑制到50%以下;辛伐他汀、替格瑞洛、多西他赛对OATP1B1的抑制作用较强,30 μmol·L^-1给药的转运活性分别为对照组的（40.09±1.95）%、（33.82±0.61）%、（45.08±0.22）%;辛伐他汀对OATP1B1、OATP1B1/A388G、OATP1B1/T521C的IC₅₀分别为14.2、＞100、＞100 μmol·L^-1,替格瑞洛的IC₅₀分别为19.1、68.4、＞100 μmol·L^-1,多西他赛的IC₅₀分别为17.6、22.9、19.3 μmol·L^-1。结论 OATP1B1基因多态性在一定程度上改变了抑制剂对转运体活性的影响程度。     

CYP3A4,CYP3A5,MDR1基因多态性与他克莫司个体间差异相关性的研究进展

他克莫司是一种新型强效免疫抑制性大环内酯类抗生素,主要通过细胞色素P450(如CYP3A4和CYP3A5等)代谢,由P-糖蛋白进行转运。越来越多的研究发现CYP3A4,CYP3A5酶及P-糖蛋白的某些基因多态性可以影响他克莫司的药代和药效。现就CYP3A4,CYP3A5及P-糖蛋白的基因变异与他克莫司个体间差异相关性研究进行综述。     

有机阴离子转运多肽1A2对药物转运的影响

有机阴离子转运多肽1A2（OATP1A2）是人体内重要的膜转运蛋白,在肝、肾、小肠、血脑屏障等组织部位进行表达,介导内、外源物质的跨细胞转运,对药物的吸收、分布和消除起着十分重要的作用。本文将对OATP1A2的组织分布和基本功能、基因多态性及其对药物转运的影响作一综述。     

多西他赛对人肺癌A549细胞增殖和凋亡的影响研究

目的探讨多西他赛对人肺癌A549细胞增殖和凋亡的影响,为临床肿瘤用药提供依据。方法采用不同浓度的多西他赛（0.1、1、10、20、50、100μmol/L）处理人肺癌A549细胞48h,采用MTT法检测A549细胞增殖情况,TUNEL法检测细胞凋亡指数,流式细胞仪检测细胞周期。结果不同浓度的多西他赛处理A549细胞后的增殖抑制率和凋亡指数均高于对照组;G2/M期细胞占总细胞的比例增加,G0/G1期细胞占总细胞的比例降低（除0.1μmol/L外）。多西他赛对A549细胞的增殖抑制率、凋亡指数、G2/M期呈浓度依赖的方式增加,G0/G1期呈浓度依赖的方式降低。结论多西他赛可促进A549增殖和凋亡,同时可将A549细胞阻断在G2/M期。     

Impacts of ABCB1 (G1199A) polymorphism on resistance,uptake, and efflux to steroid drugs

1.?P-glycoprotein (P-gp) substrates, including steroid drugs, involve in the inter-individual differences in resistant phenotype. This study was performed to evaluate whether G1199A polymorphism in ABCB1 gene can alter the sensitivity, accumulation, and transepithelial efflux to steroids in LLC-PK1 cells.

2.?The stable recombinant LLC-PK1 cell lines transfected with ABCB1 1199G and ABCB1 1199A were used to assess the sensitivity, accumulation, and transepithelial permeability to steroids.

3.?The cells transfected with 1199A allele displayed stronger resistance to aldosterone, dexamethasone, and cortisol (2.5-, 2.0-, and 1.6-fold, respectively) than cells overexpressing 1199G allele, while the two types of recombinant cells showed a similar resistance to corticosterone. The accumulation of aldosterone, dexamethasone, and cortisol in recombinant 1199A cells were significantly decreased when compared to 1199G cells (2.9-, 4.4-, and 3.9-fold, respectively). The net efflux ratios of P-gp-mediated aldosterone, dexamethasone, and cortisol in cells expressing 1199A allele were apparently greater than cells transfected with 1199G allele (3.3-, 3.5-, and 4.0-fold, respectively).

4.?The impacts of ABCB1 (G1199A) single nucleotide polymorphism on the efflux of P-gp substrates presented as drug-specific. Overall, the transport ability of P-gp-dependent steroid drugs in recombinant model overexpressing variant 1199A allele is stronger in comparison to cells overexpressing wild-type 1199G allele. Therefore, the ABCB1 (G1199A) polymorphism may affect effective steroids concentration in target cells by regulating the drug transport and distribution.     

ABCB1 G1199A polymorphism and ovarian cancer response to paclitaxel

P-glycoprotein (P-gp), encoded by the ABCB1 gene, confers multi-drug resistance to a variety of antineoplastic agents, for example, paclitaxel. Recently, the G1199T/A polymorphism in the ABCB1 gene was shown to be important for the function of P-gp as well as for the resistance to several chemotherapeutic agents in vitro. We analyzed the allelic distribution of the G1199T/A and other polymorphisms in exons 11 and 12 of the ABCB1 gene in ovarian cancer patients treated with paclitaxel and carboplatin in order to evaluate their predictive value in vivo. The SNPs C1236T, G1199T/A, and A1308G were determined using Pyrosequencing in 51 patients with advanced ovarian cancer and correlated to the progression free survival. The G1199T/A SNP was found to affect the progression free survival. Although only two heterozygous (G/A) patients were found their mean progression free survival was only 2 months as compared to 19 months for the wild-type patients. This is in accordance with the higher resistance for the 1199A genetic variant found in vitro. Genotyping of the ABCB1 gene may be important for determining the tumor resistance to paclitaxel and provide useful information for individualized therapy.     

A novel MDR1 G1199T variant alters drug resistance and efflux transport activity of P-glycoprotein in recombinant Hek cells

The human multidrug resistance gene MDR1 encodes the protein product P-glycoprotein (P-gp). P-gp is an integral membrane protein which mediates ATP-dependent substrate efflux. We recently discovered a novel G --> T variant at 1199 nucleotide position of MDR1 which exhibits a 2.3% allelic frequency in leukemia patients. The functional effects of this MDR1-G1199T variant were evaluated with recombinant HEK cells that stably express the wild-type, G1199A, or G1199T variant of the MDR1 protein, P-gp, at comparable levels. A panel of cytotoxic P-gp substrates comprising doxorubicin, vinblastine, vincristine, paclitaxel, or topotecan (a poor P-gp substrate) was used to evaluate the functional impact of G1199 variations. Compared to MDR1(wt), MDR1(G1199A) exhibited an increased resistance to doxorubicin, paclitaxel, vinblastine, and vincristine. In contrast, MDR1(G1199T) reduced resistance to (1/4) that of MDR1(wt) for all drugs except topotecan. Expression of MDR1 exhibits some degree of resistance to topotecan, but 1199 variation has no impact. These data were consistent with the variation in intracellular doxorubicin concentrations measured in MDR1 recombinant cells. Our results suggest that patients with the novel MDR1-G1199T variant may exhibit a lower degree of MDR1 dependent chemoresistance, and those with the G1199A polymorphism may exhibit a higher degree of resistance, compared with MDR1 wild-type patients.     

Influence of adenosine triphosphate and ABCB1 (MDR1) genotype on the P-glycoprotein-dependent transfer of saquinavir in the dually perfused human placenta

BACKGROUND: The ATP-dependent drug-efflux pump, P-glycoprotein (P-gp) encoded by ABCB1 (MDR1), plays a crucial role in several tissues forming blood-tissue barriers. Absence of a normally functioning P-gp can lead to a highly increased tissue penetration of a number of clinically important drugs. METHODS: We have studied the dose-response effect of exogenous ATP on the placental transfer of the well-established P-gp substrate saquinavir in 17 dually perfused human term placentas. We have also studied the influence of the ABCB1 polymorphisms 2677G>T/A and 3435C>T on placental P-gp expression (n = 44) and the transfer (n = 16) of saquinavir. RESULTS: The present results indicate that the addition of exogenous ATP to the perfusion medium does not affect the function of P-gp as measured by saquinavir transfer across the human placenta. The variant allele 3435T was associated with significantly higher placental P-gp expression than the wild-type alleles. However, neither polymorphism affected placental transfer of saquinavir nor there was any correlation between P-gp expression and saquinavir transfer. CONCLUSIONS: Our results indicate that addition of exogenous ATP is not required for ATP-dependent transporter function in a dually perfused human placenta. Although the ABCB1 polymorphism 3435C>T altered the expression levels of P-gp in the human placenta, this did not have any consequences on P-gp-mediated placental transfer of saquinavir.     

Effect of MDR1 gene polymorphism on progression of end-stage renal disease

AIM: P-glycoprotein is localized at the apical brush-border membrane of the proximal renal tubule and functions as extruding toxins and xenobiotics out of cells. The difference of P-glycoproteinos function resulted from single nucleotide polymorphisms in MDR1 (multidrug resistance gene encoding for P-gp) and may be the cause of interindividual differences in susceptibility to end-stage renal disease (ESRD). The purpose of this study is to compare the genotype frequency of C3435T and G1199A polymorphisms in MDR1 between ESRD patients and healthy controls in the Chinese population to determine whether the alteration of the P-gp function is associated with ESRD. METHODS: Two hundred and eighty-four healthy Chinese controls and 244 Chinese patients with ESRD were involved in this study. Allele specific PCR and polymerase chain reaction-restriction fragment length polymorphism assay were used to determine the genotype MDR1 G1199A and C3435T, respectively. RESULTS: The genotype distribution of 3435CC, 3435CT, and 3435TT were 0.35, 0.50, and 0.15, respectively, in the control group and 0.38, 0.47, and 0.15 in the group with the ESRD patients. No variant allele 1199G>A was found in any of the patients. The value of serum creatinine for genotypes 3435CC, 3435CT, and 3435TT in the ESRD patients were 753.8+/-276.0 mumol/L, 849.6+/-342.2 micromol/L, and 987.0+/-512.0 micromol/L, respectively. The difference between 3435TT and 3435CC reached statistical significance (P<0.05). CONCLUSION: The low expression of P-glycoprotein was not the etiological factor for the kidney disease, but it may contribute to the progression of ESRD and affect the severity. Chinese people do not carry the 1199G>A variant allele. More studies are needed to clarify the cause and interindividual differences in the susceptibility for the risk of ESRD.     

No influence of 3435C>T ABCB1 (MDR1) gene polymorphism on risk of adult acute myeloid leukemia and P-glycoprotein expression in blast cells

Inherited differences in xenobiotic transport and metabolism may play an important role in the development of adult acute myeloid leukemia (AML) and response to the chemotherapy. An ATP-binding cassette (ABC) family transporter P-glycoprotein (P-gp or ABCB1), encoded by ABCB1 (MDR1) gene, is involved in the protection against xenobiotics and multi-drug resistance. The aim of this study was to investigate the potential involvement of the ABCB1 gene exon 26 3435C>T single nucleotide polymorphism (SNP) in the genetic susceptibility to AML and regulation of P-gp expression and activity in AML cells. A total of 180 adult AML patients and 180 sex-matched controls were genotyped using PCR-RFLP method. Moreover, in 40 AML patients ABCB1 gene expression was studied by real-time RT-PCR and P-gp expression and activity were assessed by flow cytometry assays. The prevalence of 3435C>T ABCB1 polymorphism was similar in patient and control cohorts (P = 0.16). Furthermore, the carriers of different ABCB1 genotypes did not differ significantly according to ABCB1 gene expression (P = 0.99), P-gp expression (P = 0.42) and P-gp activity (P = 0.83) in leukemic cells. The authors conclude that isolated 3435C>T ABCB1 SNP is not a major factor of the genetic susceptibility to adult AML, and that genotyping of this polymorphism does not allow predicting P-gp expression or activity in AML cells.     

MDR1 (ABCB1) gene polymorphism C3435T is associated with P-glycoprotein activity in B-cell chronic lymphocytic leukemia

Functional single nucleotide polymorphism (SNP) C3435T in exon 26 of the MDR1 ( ABCB1 ) gene encoding the xenobiotic transporter P-glycoprotein (P-gp, MDR1, ABCB1) may influence susceptibility to several diseases as well as clinical outcome of treatment with P-gp substrates. Exposure to environmental chemicals is thought to be involved in the pathogenesis of B-cell chronic lymphocytic leukemia (B-CLL) and P-gp-transported drugs are used in its treatment; however, little is known about the impact of the C3435T MDR1 SNP in B-CLL. In this study, 110 Caucasian B-CLL patients and 201 healthy controls were genotyped for the MDR1 C3435T SNP. Additionally, P-gp activity was assessed in malignant lymphocytes of 22 untreated B-CLL patients. We observed a higher frequency of carriers of at least one 3435T allele (3435CT and 3435TT genotypes) among B-CLL patients as compared to normal individuals (76% vs . 63%, p=0.027). The genotypes 3435CT and 3435TT were associated with B-CLL, (odds ratio=1.8, 95% confidence interval = 1.1-3.0). Moreover, P-gp activity in B-CLL cells depended on MDR1 genotype, with the highest P-gp activity in 3435CC homozygotes, intermediate in 3435CT heterozygotes and the lowest in 3435TT homozygotes (p=0.042). P-gp activity was also significantly lower in carriers of the T-allele (3435CT/TT genotype) as compared to the non-carriers (3435CC genotype), (p=0.029). Taken together, these data indicate that the MDR1 C3435T SNP may carry an increased risk of developing B-CLL, possibly by virtue of decreased protection against P-gp-substrate carcinogens. The differences in P-gp activity in B-CLL tumor cells related to MDR1 genotype may have implications to the response to chemotherapy with P-gp transported anticancer agents.     

1199G>A and 2677G>T/A polymorphisms of ABCB1 independently affect tacrolimus concentration in hepatic tissue after liver transplantation

OBJECTIVE: Tacrolimus is an immunosuppressive drug widely used in hepatic transplantation to avoid graft rejection. Its pharmacokinetics is characterized by a large interindividual variability requiring the use of therapeutic drug monitoring in daily clinical practice. Some genetic polymorphisms in biotransformation enzymes or transporter proteins, such as CYP3A5 and P-glycoprotein (ABCB1), in donors and/or recipients, appear as important determinants of the Tac blood pharmacokinetics. A recent study has shown that Tac hepatic tissue concentrations vary greatly among patients and are well correlated with graft outcome. The aim of our study was to investigate the effect of genetic polymorphisms in biotransformation enzymes (CYP3A5 and CYP3A7) or in their regulatory protein pregnane X receptor as well as in transporter proteins (ABCB1 and OATP-C) on Tac pharmacokinetics in liver transplant patients and more specifically on Tac hepatic concentrations. METHODS: One hundred and fifty liver donors were genotyped for 13 different polymorphisms. Tac blood and hepatic concentrations were compared according to hepatic genotypes. RESULTS AND CONCLUSION: We confirmed that Tac dose requirement (on the basis of blood therapeutic drug monitoring) was higher among patients expressing hepatic CYP3A5 (at least one CYP3A5*1 allele) compared with patients who did not (CYP3A5*3/*3). Hepatic expression of CYP3A5, however, did not seem to influence Tac hepatic concentrations. In contrast, ABCB1 genetic polymorphisms significantly influenced Tac hepatic concentrations, whereas their impact on blood concentrations seemed negligible. Among these ABCB1 polymorphisms, the 1199G>A and 2677G>T/A single nucleotide polymorphisms seemed to reduce the activity of P-gp on Tac. As Tac hepatic concentrations have been significantly related to the graft outcome, it might be interesting, in the future, to genotype donors for ABCB1 polymorphisms to better individualize the Tac immunosuppressive therapy in hepatic transplantation.