Detection of C1236T,G2677T/A,and C3435T polymorphism of MDR1 by amplification refractory mutation system PCR

C1236T, G2677T/A, and C3435T polymorphism of the multidrug resistance (MDR1) gene have substantial impact on expression or activity of P‐glycoprotein (P‐gp). We developed new methods based on amplification refractory mutation system (ARMS) to detect these polymorphisms. Tetra‐primers amplification in a single tube was established to detect C1236T and C3435T polymorphism. For G2677T/A polymorphism, a two‐step allele‐specific amplification method was used. MDR1 genotypes of 177 Chinese subjects were determined by the methods we established. The methods we established were verified with gene sequencing. Gene frequencies of 1236C and 1236T were 37.8 and 62.2%, respectively; gene frequencies of 2677G, 2677T and 2677A were 44.1, 38.4 and 17.5%, respectively; the gene frequencies of 3435C and 3435T were 65.0 and 35.0%, respectively. The results were similar with other studies on Oriental subjects. The methods we established are simple, accurate, and economical, and can provide reliable approaches for determining MDR1 polymorphism. J. Clin. Lab. Anal. 23:110–116, 2009. © 2009 Wiley‐Liss, Inc.     

多药耐药基因C3435T与G2677T/A单核苷酸多态性检测方法的探讨

目的 建立简便、快速检测多药耐药基因(MDR1)C3435T与G2677T/A单核苷酸多态性(SNPs)的方法 .方法 针对MDR1 C3435T分别设计相对的两对引物-聚合酶链反应(PCR-CTPP)、序列特异性聚合酶链反应(PCR-SSP)及DNA测序方法 的引物,针对MDR1 G2677T/A分别设计PCR-SSP和DNA测序方法 的引物,优化PCR反应条件.将PCR-CTPP和PCR-SSP方法 的基因分型结果 与DNA测序结果 进行比对,确定准确性.在优化条件下,分别对50例健康体检者的外周血白细胞DNA进行MDR1 C3435T和C2677T/A基因型分析.结果 通过条件优化,PCR-CIPP、PCR-SSP方法 可快速的清晰区分MDR1 C3435T与G2677T/A的基因型,结果 与DNA测序方法 相符合.50例健康体检个体MDR1 C3435T与G2677T/A的基因型分布均符合Hardy-Weinberg平衡(P0.05).MDR1 C3435T PCR-CTPP结合G2677T/A PCR-SSP的检测方法 为最佳选择.结论PCR-CTPP、PCR-SSP方法 可简单、准确、经济、快速地检测MDR1 C3435T、G2677T/A SNPs,具有临床应用价值.     

建立对多药耐药基因C3435T与G2677T单核苷酸多态性的快速分型方法

目的:建立快速的序列特异性聚合酶链反应(SSP-PCR)方法,检测人多药耐药基因C3435T、G2677T两个单核苷酸多态性.方法:优化SSP-PCR反应条件,将其结果与DNA测序进行比对,确定其准确性.采集158例汉族正常人的外周血,检测MDR1 C3435T和G2677T基因的变异情况.结果:优化后SSP-PCR结果与测序结果相符合.158例个体C3435T基因分布,C纯合子占37.34%,T纯合子占11.39%,C/T杂合子占51.27%.G2677T基因分布,G、T、A等位基因出现频率分别为44.30%、39.24%、16.46%.汉族人中此两位点多态性分布与高加索人存在显著差异(P＜0.05).结论:本研究成功建立了SSP-PCR MDR1 C3435T、G2677T单核苷酸多态性的快速分型技术.     

Easy detection of 5,10-methylenetetrahydrofolate reductase 1298A/C genotype by mutagenically separated PCR assay.

BACKGROUND: 5,10-Methylenetetrahydrofolate reductase (MTHFR) plays a central role in folate metabolism. Previous studies have suggested an association between the MTHFR 1298A/C polymorphism and several diseases, such as cardiovascular and psychiatric diseases, neural tube defects, diabetes, and cancer. Currently, either PCR-restriction fragment length polymorphism (RFLP) technique or real-time PCR using Taqman assay are used to determine the MTHFR 1298 genotype. METHODS: We developed a simple and efficient approach that employs mutagenically separated PCR to genotype MTHFR 1298A/C polymorphism. Two forward mutagenic allele-specific primers of different lengths for MTHFR 1298A/C were paired with the same reverse primer in a one-tube assay to genotype 20 genomic DNA samples. RESULTS: Electrophoresis on 2.5% agarose gel showed two allele-specific fragments, a 113-bp A allele-specific and a 93-bp C allele-specific PCR product. The results were confirmed by the conventional PCR-RFLP method. CONCLUSIONS: We conclude that mutagenically separated PCR could be used as an alternative simple, reliable, and cost-effective method for the genotyping of MTHFR 1298A/C polymorphism.     

MDR1 polymorphisms G2677T in exon 21 and C3435T in exon 26 fail to affect rhodamine 123 efflux in peripheral blood lymphocytes

P-glycoprotein (Pgp) is a member of the ABC-transporter family, and in humans, is encoded by the MDR1 gene. Recently, several single-nucleotide polymorphisms in the MDR1 gene were identified. The aim of the present study was to evaluate the effect of the MDR1 genetic polymorphisms G2677T and C3435T on Pgp activity in CD56+ and CD4+ peripheral blood cells. Using flow cytometry, rhodamine 123 (Rh123) efflux was determined in 46 male healthy volunteers. Median Rh123 fluorescence in control sample, after baseline dye uptake, was set as 100%. Rh123 fluorescence in efflux samples, exposed to different efflux periods, was used to calculate the percentage of Rh123 retained in the cells in comparison with control. There was no significant difference in Rh123 efflux in CD56+ cells after 5, 10, 15, and 30 min efflux between individuals with different MDR1 genotypes. Also, in CD4+ cells after 15, 30, 60, and 90 min, Rh123 efflux did not reveal statistically different results for the three genotypes at 2677 and 3435. Rh123 efflux was not enhanced by a 10-day rifampin administration, as determined in 15 individuals before and after rifampin treatment. In conclusion, we found no impact of the MDR1 G2677T and C3435T polymorphisms on Pgp activity in CD56+ and CD4+ peripheral blood lymphocytes.     

多药耐药基因多态性和单倍体对环孢素A血药浓度的影响

目的探讨中国健康志愿者中多药耐药基因(MDR1)12外显子C1236T、21外显子G2677T/A和26外显子C3435T多态性及3个位点单倍体连锁不均衡性对环孢素A(CsA)药代动力学特性的影响。方法高效液相色谱法(HPLC)测定20名健康男性单次口服CsA500mg后,24h中不同时间点的血药浓度。采用聚合酶链反应(PCR)结合基因测序法测定3个位点的基因多态性和单倍体类型。结果20名男性健康志愿者中,C1236T位点1名为CC型,8名为CT型,11名为TT型;G2677A/T位点4名为GG型,7名为GT型,4名为AT型,5名为TT型;C3435T位点5名为CC型,11名为CT型,4名为TT型;MDR1的C1236T和G2677A/T的基因多态性与峰浓度(Cmax)和药时曲线下面积(AUC0inf)差异均无统计学意义(均P>0.05),C3435T的基因多态性与Cmax无相关性(P>0.05),而与AUC0inf相关(P<0.05)。CC型、CT型和TT型的Cmax分别为2124.7±179.4ng/ml、1934.2±372.8ng/ml和1765.2±415.6ng/ml;AUC0inf分别为13922.4±2881.5ng/h-1·ml、11511.8±2192.1ng/h-1·ml和8514.9±1063.4ng/h-1·ml;至少含有1个C等位基因的基因型(CC型和CT型),二者的AUC0inf比TT型增高49%。单倍体分析表明,26与12和21外显子间存在单核苷酸多态性的连锁不均衡性,不同单倍体类型对CsA药动力学特性无影响(P>0.05)。结论MDR1C3435T的多态性可能是口服CsA后,生物利用度变异大的影响因素。     

The genetic variability of MDR1 C3435T polymorphisms in four Southern Chinese populations

Objectives

To investigate the genetic variability of multiple drug resistant 1 (MDR1) gene C3435T polymorphism in four Southern Chinese populations.

Methods

Using discrimination real-time PCR, we determined the MDR1 C3435T polymorphism in three ethnic minority groups Lahu (n = 104), Wa (n = 101) and Bulang (n = 100) in Yunnan Province, and Han Chinese (n = 199) in Hong Kong. All of them were residents in Southern China.

Results

For 3435 CC genotype, the frequency in Han Chinese in Hong Kong (44.7%) is significantly higher than in Lahu (16.3%) and Wa (29.7%) minorities, P < 0.05. For 3435 CT genotype, the frequency in Han Chinese in Hong Kong (44.2%) is lower than in Lahu (58.7%), P < 0.05. For 3435 TT genotype, frequency in Han Chinese in Hong Kong (11.1%) is lower than in Lahu (25%) and Wa (20.8%), P < 0.05. For 3435 C allele, frequency in Han Chinese in Hong Kong (66.8%) is higher than in Lahu (45.7%) and Wa (54.5%), P < 0.01. For 3435T allele, frequency in Han Chinese in Hong Kong (33.2%) is lower than in Lahu (54.3%) and Wa (45.5%), P < 0.01. For MDR1 3435T allele, the frequencies are significantly higher in our four Southern Chinese populations than in African population (P < 0.001) and significantly lower than in South-west Asians (P < 0.05); Han Chinese in Hong Kong displayed significant difference from all the other ethnic populations except Japanese (P < 0.05); compared with Caucasian and other ethnic Asians, Lahu minority showed no frequency difference (P > 0.05) between Caucasian and other Asians (except Japanese).

Conclusions

This is the first study to show the C3435T polymorphism of MDR1 in Southern Chinese populations. The frequency of C3435T, an important determinant for multidrug resistance, displays significant difference in ethnics. It may help for individualizing therapy for cancer, HIV and other common diseases.     

Simple and rapid detection of uncoupling protein-2 - 866G/A polymorphism by mutagenically separated polymerase chain reaction

BACKGROUND: Uncoupling protein-2 (UCP2), a recently identified member of the mitochondrial transporter superfamily, is a candidate gene for obesity. A common G/A polymorphism in the UCP2 promoter region is associated with enhanced adipose tissue mRNA expression in vivo. METHODS: We developed a rapid and simple method, mutagenically separated polymerase chain reaction (MS-PCR) for genotyping UCP2 - 866G/A polymorphism. Two reverse mutagenic allele-specific primers of different lengths for the UCP2 - 866G/A polymorphic site were paired with the same forward primer in the same PCR reaction. RESULTS: Agarose gel electrophoresis (3.5%) showed at least one of the two allelic products and provided a within-assay quality control to exclude false-negative results. The 203-bp fragment of the PCR products was A allele-specific and the 183-bp fragment was G allele-specific. The frequencies of the UCP2 - 866G/A genotypes in 72 Japanese subjects were AA: 21 (29.2%), AG: 32 (44.4%), and GG: 19 (26.4%). The results were confirmed by the PCR-RFLP genotyping method, in which a 360-bp fragment of PCR products was cut into 290- and 70-bp fragments by the restriction enzyme MluI when the G allele was present. This Japanese group showed a higher frequency of the AA genotype, which is associated with a low prevalence of obesity, than Caucasian populations. CONCLUSIONS: The MS-PCR technique is a simple, rapid, and reliable method for genotyping UCP2 - 866G/A polymorphism.     

No effect of MDR1 C3435T variant on loperamide disposition and central nervous system effects

BACKGROUND: The MDR1 gene encodes the efflux transporter P-glycoprotein, which is highly expressed in the small intestine and in the blood-brain barrier. A major function of P-glycoprotein is to limit the absorption and central nervous system exposure of numerous xenobiotics. A genetic polymorphism in the MDR1 gene (C3435T) has been associated with changes in the intestinal expression level and function of P-glycoprotein. The aim of this study was to investigate the effect of this polymorphism on disposition and brain entry of the P-glycoprotein substrate loperamide. METHODS: Healthy white volunteers were genotyped for the MDR1 C3435T polymorphism, and a 16-mg oral dose of loperamide was administered to 8 subjects with the 3435TT genotype and 8 subjects with the 3435CC genotype. Plasma levels of loperamide were determined by liquid chromatography-tandem mass spectrometry. Loperamide-induced respiratory depression was detected as the ventilatory response to carbon dioxide and was used as a measure of central nervous system side effects. RESULTS: We found no significant difference in loperamide pharmacokinetics between individuals homozygous for the C and the T alleles in position 3435 of MDR1, as follows: peak plasma drug concentration, 3164 +/- 1053 pg/mL and 3021 +/- 984 pg/mL; area under the concentration-time curve from 0 to 8 hours, 14414 +/- 4756 pg. h/mL and 14923 +/- 6466 pg. h/mL; and time to peak plasma drug concentration, 3.9 +/- 1.4 hours and 3.9 +/- 2.6 hours for the MDR1 3435CC and 3435TT genotypes, respectively (P >.05, for all parameters). Hypercapnic ventilatory response changed only minimally after ingestion of loperamide (the coefficient of variation during the 0- to 8-hour period was 21% +/- 14% for the sample population), and there was no MDR1 3435 genotype-related effect on respiratory response. Carriers of the 2 major MDR1 haplotypes, MDR1*1 and MDR1*13, did not differ in their response to loperamide. CONCLUSION: There was no association between the MDR1 C3435T variation and plasma levels or central nervous system effects of the P-glycoprotein substrate loperamide in a white study population. The MDR1 haplotype structure was quite variable and supports the use of haplotypes instead of single nucleotide polymorphisms in determining clinical consequences of genetic variation.     

MDR1基因＋3435C/T基因型单核苷酸多态性对硼替佐咪治疗的多发性骨髓瘤预后的影响

目的探讨MDR1基因＋3435C/T的单核苷酸多态性对硼替佐咪治疗的多发性骨髓瘤患者预后的影响。方法采用DNA测序方法检测MDR1基因＋3435C/T的单核苷酸多态性;应用Kaplan-Meier来确认MDR1基因＋3435C/T的单核苷酸多态性对硼替佐咪治疗/未治疗患者生存率的影响。结果 52.8%（n=47）的多发性骨髓瘤患者MDR1＋3435位点的基因型为C/T,其余多发性骨髓瘤患者MDR1＋3435位点的基因型均为T/T。MDR1＋3435C/T基因型的患者的平均生存期为43.3月,而MDR1＋3435T/T基因型的患者的平均生存期为37.5月,二者有显著差异性（P=0.024）。在硼替佐咪治疗（n=44）组中,MDR1＋3435C/T（n=22）与MDR1＋3435T/T（n=22）基因型相比,患者生存期有显著差异（P=0.041）。结论本实验中,相比于MDR1＋3435T/T基因型,多发性骨髓瘤患者的MDR1＋3435C/T基因型具有高频性,该多态性对硼替佐咪治疗的多发性骨髓瘤患者生存期有显著影响。     

精神分裂症外周血中多药耐药基因C1236T多态性与帕利哌酮缓释片疗效相关性研究

目的 探讨精神分裂症患者外周血中多药耐药基因C1236T位点的基因多态性与帕利哌酮缓释片疗效的相关性.方法 对68例精神分裂症患者予以口服帕利哌酮缓释片治疗,观察6周.采用阳性与阴性症状量表、简明精神病量表评定临床疗效,个人和社会功能量表评定社会功能.治疗后根据阳性与阴性症状量表总分减分率(≥50％为有效)将患者分为有效组和无效组.采用聚合酶链反应-限制性片段长度多态性分析技术检测其多药耐药基因C1236T位点的基因型.将有效组和无效组的基因型进行对比分析.结果 本组患者治疗6周后阳性与阴性症状量表总分及各因子分、简明精神病量表总分均较治疗前显著下降,个人与社会功能量表总分较治疗前显著升高(P＜0.01).有效组与无效组基因型频率比较差异无显著性(P＞0.05).结论 帕利哌酮缓释片治疗精神分裂症疗效显著,未发现多药耐药基因C1236T位点的多态性与帕利哌酮缓释片的疗效有关.     

Secretor genotyping for A385T, G428A, C571T, C628T, 685delTGG, G849A, and other mutations from a single PCR

BACKGROUND: The secretor status of an individual is important for disease relationship studies, because it determines the presence of ABH blood group antigens in the gastrointestinal tract and bodily secretions. Routine serologic methods for determining secretor status are unreliable. Current strategies based on PCR for genotyping require relatively large amounts of DNA and have to be done as several separate experiments. STUDY DESIGN AND METHODS: A single, multiplex PCR technique followed by RFLP digestion with four restriction enzymes produced unique genotype profiles for most known secretor (FUT2) mutations. RESULTS: Samples from a range of individuals with common and rare secretor genotypes were analyzed. Each gave unique patterns that allowed secretor genotypes to be determined. CONCLUSION: By using the method described here and genomic DNA, a secretor genotype based on the FUT2 mutations A385T, G428A, C571T, C628T, 685delTGG, and G849A could be accurately determined.     

Effect of the mutation (C3435T) at exon 26 of the MDR1 gene on expression level of MDR1 messenger ribonucleic acid in duodenal enterocytes of healthy Japanese subjects

The effect of the C3435T mutation at exon 26 of the MDR1 gene on the expression levels of MDR1 messenger ribonucleic acid (mRNA) was evaluated by means of real-time polymerase chain reaction in 51 biopsy specimens of duodenum obtained from 13 healthy Japanese subjects. The mRNA levels of MDR1 were 0.38 +/- 0.15, 0.56 +/- 0.14, and 1.13 +/- 0.42 (mean value +/- SE) in the subjects with the homozygote of wild-type allele (C/C), compound heterozygote with mutant T allele (C/T), and the homozygote of the mutant allele (T/T), respectively, reasonably explaining the lower digoxin serum concentration after administration of a single oral dose to subjects harboring a mutant T allele. Good correlation (r =.797; P <.01) was observed between the mRNA concentrations of MDR1 and CYP3A4 in the individual biopsy specimens. This finding suggested a lower plasma concentration of the substrates for CYP3A4 in subjects harboring the C3435T mutation of the MDR1 gene.     

多重实时荧光定量PCR同时检测急性白血病患者WT1和MDR1基因表达水平方法的建立

目的 构建可同时检测AL患者WT1和MDR1基因表达水平的多重实时荧光定量PCR方法.方法 提取K562细胞的总RNA,并逆转录扩增WT1和MDR1的cDNA,通过Bam H Ⅰ及BglⅡ酶切后连接成WT1和MDR1重组片段,对WT1和MDR1重组片段进行PCR扩增,PCR产物纯化后与pMD18载体进行连接,转化宿主菌DH-5α,构建载有WT1和MDR1基因的标准品重组质粒,用限制性核酸内切酶法和PCR法鉴定质粒.用FAM荧光标记MDR1探针、VIC荧光标记WT1探针,建立能在1个试管中同时检测WT1和MDR1基因表达水平的多重实时荧光定量PCR反应体系.应用该体系检测47例AL患者及32例对照者WT1和MDR1基因表达水平,比较两组之间WT1和MDR1基因表达水平的差异,并随访7例AL患者不同病程中WT1和MDR1基因表达水平的变化与临床预后的关系.结果 经EcoR1酶切及PCR法证实WT1和MDR1基因重组质粒已成功构建.所建立多重实时荧光定量PCR方法的灵敏度为102拷贝/μl;所建立标准曲线的R2分别为0.999和0.998.AL患者WT1和MDR1基因的表达水平中位数分别为37 000(163～6 370 000)拷贝/μg RNA和76 200(179～18 000 000)拷贝/μg RNA,显著高于对照组的258(0～643)拷贝/μg RNA和333(0～779)拷贝/μg RNA,差异有统计学意义(Z=6.755、6.736,P＜0.01).对应用相同的诱导和巩固化疗方案治疗的7例AL患者进行随访,3例持续缓解患者中,WT1和MDR1的表达水平在初治时分别为2 170和86 900、1 130和5 860、1 170和586拷贝/μg RNA,治疗后WT1和MDR1的表达水平明显下降,分别为370和560、138和980、150和690拷贝/μg RNA,此3例患者获长期完全缓解.在3例完全缓解后复发患者中,WT1和MDR1表达水平在初治时分别为1 600和11800、24 800和968、48 200和1 100 000拷贝/μg RNA,在化疗获得完全缓解后均降低,但在随后治疗过程中,WT1、MDR1表达量又逐渐升高,分别为20 314和25 660、184 364和31 530、15 680和878 000拷贝/μg RNA,此3例患者最终均出现临床复发.另外1例未缓解患者初治时WT1和MDR1表达水平分别为81 600和1 200 000拷贝/μg RNA,化疗后WT1、MDR1表达水平不仅未下降,反而有所上升,分别为124 100和7 632 400拷贝/μg RNA,此例患者始终未获缓解.结论 本研究成功构建了可同时检测WT1和MDR1基因表达水平的多重实时荧光定量PCR方法.同时检测AL患者WT1和MDR1基因表达水平的变化可能有助于判断预后.

Abstract：

Objective To set up a multiplex real time quantitative PCR method to detect the expression of WT1 and MDR1 gene simultaneously in acute leukemia patient. Methods Total RNA was extracted from k562 cell line and was reverse transcribed to cDNA by the outer primers of WT1 and MDR1 respectively. The cDNA of WT1 and MDR1 were purified and digested by Bam H Ⅰ and Bgl Ⅱ , and then the two fragments were ligated to form the recombinant fragment WT1 + MDR1. The outer forward primer of WT1 and outer reverse primer of MDR1 were used to amplify the recombinant fragment WT1 + MDR1. The PCR product was purified and cloned into pMD18-T vector, and then transferred into E. coli DH-5α. A new kind of WT1-MDRl-contained standard plasmid was obtained from the positive colony. The recombinant plasmid was verified by digestion with restriction enzyme and PCR amplification. A multiplex real time quantitative PCR method was set up with FAM-labeled MDR1 probe and VIC-labeled WT1 probe in one reaction tube. The WT1 and MDR1 gene expression was detected in forty-seven AL patients and thirty-two controls by this method. Seven patients were followed-up to elucidate the relationship between the gene expression levels and clinical prognosis. Results The recombinant plasmid was confirmed by EcoR1 digestion and PCR amplification. The multiplex real time quantitative PCR technique could reach the sensitivity of WT1 and MDR1 gene up to 102 copy/μl. The standard curve slopes were 0. 999 and 0. 998. The WT1 [ 37 000( 163-6 370 000 )copies/μg RNA ] and MDR1 [ 76 200( 179-18 000 000 )copies/μg RNA ]expression levels of AL patients were significantly higher as compared to the controls [ 258( 0-643 ) copies/μg RNA and 333( 0-779 )copies/μg RNA ]( Z= 6. 755,6. 736, P ＜ 0. 01 ). Following up seven patients with similar regimen of chemotherapy, the WT1 and MDR1 expression correlated to the clinical course. Three AL patients with WT1 and MDR1 expression levels (2 170 and 86 900, 1 130 and 5 860, 1 170 and 586 copies/μg RNA )significantly decreased after chemotherapy and kept in the low range ( 370 and 560,138 and 980, 150 and 690 copies/μg RNA ), and had a favorable outcome. Three AL patients with WT1 and MDR1 expression levels ( 1 600 and 11 800, 24 800 and 968, 48 200 and 1 100 000 copies/μg RNA )decreased after initial chemotherapy, but increased significantly afterwards (20 314 and 25 660,184 364 and 31 530, 15 680 and 878 000 copies/μg RNA ),and suffered clinical relapse. One patient with high WT1 and MDR1 expression levels ( from 81 600 and 1 200 000 copies/μg RNA to 124 100 and 7 632 400 copies/μg RNA )showed the persistence of disease. Conclusions A multiplex real time quantitative PCR method to detect WT1 and MDR1 gene simultaneously is constructed successfully. The expression of WT1 and MDR1 may provide useful information for AL patients prognosis.     

快速检测中国人群C2938T、G1846T、G1846A、C188T点突变

背景细胞色素P450单氧化酶的活性可以通过检测CYP2D6等位基因的基因型，来确定其表型。在白种人中，使用简单的一步法检测其等位基因的分布频率已有报道，但在中国人中的报道却不多。方法建立3个tetraprimerPCR和1个ASA—PCR方法检测223例中国人CYP2D6中C2938T、G1846T、G1846A、C188T点突变。结果中国人群中CYP2D6突变最多的等位基因是＊10（C188T），频率为51．3％；其次是＊2（C2938T），频率为15．5％；新的等位基因＊14B分布频率为2．0％。这个新的等位基因＊14B与＊14不同，它缺乏C188T突变，但有G1749C突变。结论中国大陆CYP2D6等位基因分布频率与其他地区的中国人略有不同，提示基因型检测可为药物个体化应用提供依据。