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Tacrolimus has been used to induce remission in patients with steroid-refractory ulcerative colitis. It poses a problem of large individual differences in dosage necessary to attain target blood concentration and, often, this leads to drug inefficacy. We examined the difference in mRNA expression levels of ATP binding cassette transporter B1 (ABCB1) between inflamed and non-inflamed tissues, and the influence of CYP3A5 genotype on tacrolimus therapy. The mRNA expression of CYP3A4 in colonic mucosa and that of cytochrome p450 3A5 (CYP3A5) and ABCB1 in inflamed and non-inflamed areas were examined in 14 subjects. The mRNA expression levels of CYP3A5 were higher than that of CYP3A4. The mRNA expression of ABCB1 was lower in the inflamed than in the non-inflamed mucosa, despite that of CYP3A5 mRNA level being not significantly changed. Hence, the deterioration of the disease is related to the reduction of the barrier in the inflamed mucosa. The relationship between CYP3A5 genotype and blood concentration, dose, and concentration/dose (C/D) ratio of tacrolimus in 15 subjects was studied. The tacrolimus dose to maintain equivalent blood concentrations was lower in CYP3A5*3/*3 than in CYP3A5*1 carriers, and the C/D ratio was significantly higher in the latter. Thus, CYP3A5 polymorphism information played a role in determining the initial dose of tacrolimus. Furthermore, since the effect of tacrolimus appears earlier in CYP3A5*3/*3 than in CYP3A5*1/*1 and *1/*3, it seems necessary to change the evaluation time of therapeutic effect by CYP3A5 genotype. Additionally, the relationship between CYP3A5 genotype and C/D ratio of tacrolimus in colonic mucosa was investigated in 10 subjects. Tacrolimus concentration in the mucosa was two-fold higher in CYP3A5*3/*3 than in CYP3A5*1 carriers, although no significant difference in tacrolimus-blood levels was observed. Therefore, the local concentration of tacrolimus affected by CYP3A5 polymorphism might be related to its therapeutic effect.

Objective A relationship between polymorphisms rs1128503 and rs1045642 in the multidrug resistance 1 gene ( MDR1) and susceptibility to hepatocellular carcinoma (HCC) has been reported but is inconclusive. This study was performed to explore the significance of MDR1 polymorphisms rs1128503 and rs1045642 in screening and diagnosis of HCC. Methods Studies of association analyses between MDR1 gene polymorphisms rs1128503 and rs1045642 and HCC were selected from three foreign language databases (PubMed, Cochrane, and Embase) and three Chinese databases (Wanfang, China National Knowledge Infrastructure, and China Knowledge Network) and subjected to meta-analysis. Results We found no significant relationship between the rs1128503 polymorphism and susceptibility to HCC in 4 cohorts and no significant relationship between the rs1045642 polymorphism and susceptibility to HCC in 3 cohorts. Conclusions There was no relationship between polymorphisms rs1128503 or rs1045642 of the MDR1 gene and susceptibility to HCC.

Objective The resistance to antimony-containing glucantime is a major obstacle to successful treatment, especially in endemic areas. Looking the molecular mechanisms involved in this drug resistance will help in choosing the best treatment. The aim of this study was to evaluate the expression of multidrug-resistance 1 (MDR1) and multidrug-resistance protein A (MRPA) genes in acute, chronic non-lupoid, and chronic lupoid forms of dry type cutaneous leishmaniasis (DTCL). Results MDR1 gene was over-expressed as 14.4- and 1.56-folds in the chronic lupoid and acute forms compared with the chronic non-lupoid form, respectively. Results comparison showed P

// Li-liang Xia 1, 4, * , Ya-bin Tang 2, * , Fei-fei Song 2 , Ling Xu 2 , Ping Ji 2 , Shu-jun Wang 2 , Ji-min Zhu 3 , Yong Zhang 2 , Guo-ping Zhao 1, 4, 5 , Ying Wang 2 , Tao-tao Liu 3 1 State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences and Institute of Biomedical Sciences, Fudan University, Shanghai, China 2 Shanghai Institute of Immunology, Department of Immunology and Microbiology, Department of Pharmacology and Chemical Biology, Shanghai Jiaotong University School of Medicine, Shanghai, China 3 Department of Gastroenterology, Zhongshan Hospital, Fudan University, Shanghai, China 4 Shanghai-MOST Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai, China 5 Department of Microbiology and Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR, China * These authors have contributed equally to this work Correspondence to: Tao-tao Liu, email: liu.taotao@zs-hospital.sh.cn Li-liang Xia, email: liliangxia@126.com Keywords: dCTP pyrophosphatase 1, chemoresistance to 5-fluorouracil, 5-methyl-dCTP, methylation, multidrug resistance 1 Received: March 31, 2016 Accepted: August 24, 2016 Published: September 06, 2016 ABSTRACT Gastric cancer (GC) is among the most malignant cancers with high incidence and poor prognoses worldwide as well as in China. dCTP pyrophosphatase 1 (DCTPP1) is overexpressed in GC with a poor prognosis. Given chemotherapeutic drugs share similar structures with pyrimidine nucleotides, the role of DCTPP1 in affecting the drug sensitivity in GC remains unclear and is worthy of investigation. In the present study, we reported that DCTPP1- knockdown GC cell line BGC-823 exhibited more sensitivity to 5-fluorouracil (5-FU), demonstrated by the retardation of cell proliferation, the increase in cell apoptosis, cell cycle arrest at S phase and more DNA damages. Multidrug resistance 1 (MDR1) expression was unexpectedly down-regulated in DCTPP1 -knockdown BGC-823 cells together with more intracellular 5-FU accumulation. This was in large achieved by the elevated methylation in promoter region of MDR1 gene. The intracellular 5-methyl-dCTP level increased in DCTPP1- knockdown BGC-823 cells as well. More significantly, the strong correlation of DCTPP1 and MDR1 expression was detectable in clinical GC samples. Our results thus imply a novel mechanism of chemoresistance mediated by the overexpression of DCTPP1 in GC. It is achieved partially through decreasing the concentration of intracellular 5-methyl-dCTP, which in turn results in promoter hypomethylation and hyper-expression of drug resistant gene MDR1 . Our study suggests DCTPP1 as a potential indicative biomarker for the predication of chemoresistance in GC.

Objective Studies have demonstrated that tetrandrine reverses multidrug resistance (MDR) in animal models or cell lines derived from multiple cancer types. We examined the potential MDR reversal activity of tetrandrine in a multidrug-resistant variant of a human laryngeal cancer Hep-2 cell line and explored potential mechanisms involved. Methods We developed the multidrug-resistant variant cell line (Hep-2/v) by exposing Hep-2 cells to stepwise increasing concentrations of vincristine (VCR). After Hep-2 or Hep-2/v cells were treated with tetrandrine (2.52 µg/mL), MDR was measured by MTT assay, rhodamine 123 retention was measured by flow cytometry, and mRNA and protein expression of multidrug resistance 1 (MDR1), regulator of G-protein signaling 10 (RGS10), high-temperature requirement protein A1 (HTRA1), and nuclear protein 1 (NUPR1) were detected by real-time reverse transcription-PCR and western blotting, respectively. Results Tetrandrine significantly lowered the half-maximal inhibitory concentration (IC50) of VCR in Hep-2/v cells, resulting in a 2.22-fold reversal of MDR. Treatment with tetrandrine increased rhodamine 123 retention, downregulated the mRNA and protein expression of MDR1 and RGS10, and upregulated expression of HTRA1 in Hep-2/v cells. Conclusion We showed that tetrandrine exerts anti-MDR activity in Hep-2/v cells, possibly by inhibiting MDR1 overexpression-mediated drug efflux and by altering expression of HTRA1 and RGS10.

OBJECTIVE The MDR1 gene encodes for P-glycoprotein (P-gp), which is an efflux transporter at the cell membrane. The P-gp has wide substrate specificity for multiple medications, including the antiallergic drug fexofenadine. In this study, we investigated the possible association between three common MDR1 gene polymorphisms (G2677T, C3435T, and C1236T), and the anti-allergic effect of fexofenadine among Jordanians. MATERIALS AND METHODS An assessment of the severity of allergic rhinitis symptoms was performed for all patients (n = 260) pre- and 7 days into fexofenadine. MDR1 polymorphisms were genotyped using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). RESULTS Relative to baseline, fexofenadine treatment was associated with significant reduction in allergic individual and total scores (p < 0.0001). Male gender was associated with less mean reduction in total allergic rhinitis symptoms score than in female (p < 0.05). In multivariate analysis, male gender was negatively correlated with response to fexofenadine (p = 0.01). The MDR1 gene C1236T polymorphism showed significant correlation with changes in total symptoms score from baseline in males (p < 0.05) but not in females. No significant correlation between fexofenadine response parameters and G2677T or the C3435T polymorphism was observed. CONCLUSIONS The MDR1 gene polymorphism C1236T was associated with the anti-allergic effect of fexofenadine among male Jordanians.

Background The multidrug resistance 1 gene (ABCB1) encodes P-glycoprotein (PGP), mainly expressed in the liver and engaged in metabolism of drugs including the immunosuppressant tacrolimus (TAC). ABCB1 single nucleotide polymorphisms (SNP) may significantly alter pharmacokinetics and influence TAC concentrations of kidney transplant recipients (KTR). Methods The genotype distribution of ABCB1 1236C>T, 2677G>T/A and 3435C>T was investigated among 96 Austrian KTR who were converted from cyclosporin to TAC. Dose adjusted TAC trough levels and L/D ratios were assessed at week 1, 2, 4, and 8, and month 3, 12, and 24, and the influence of ABCB1 genotypes on dose adjusted TAC trough levels and level to dose (L/D) ratios were analyzed. Results The genotype distributions for ABCB1 1236C>T were CC 36.4%, CT 5.2%, TT 58.3%, for ABCB1 2677G>T/A GA 2%, GG 63.5%, GT 20.8%, TA 1%, TT 12.5%, and for ABCB1 3435C>T CC 20.8%, CT 7.2%, TT 71.8%. Dose adjusted TAC trough levels and L/D ratios were independent of ABCB1 genotypes except for ABCB1 1236C>T at a single time point (week 2: 0.02599 [CC] vs. 0.05704 [CT] vs. 0.03218 [TT]; p = 0.024). Conclusions Serial analyses of TAC trough levels revealed no significant association with important ABCB1 genotypes among stable long-term Austrian KTR.

UNLABELLED Prostate cancer is one of the most common malignancies in men. The multidrug resistance 1 gene (MDR1) is an important candidate gene for prostate cancer. The aim of this study was to evaluate the association between MDR1 gene polymorphisms and the risk of prostate cancer. MDR1 gene polymorphism and its association with the risk of prostate cancer were investigated in 357 Chinese men. A novel c.1465C>T polymorphism was detected with created restriction site-polymerase chain reaction and DNA sequencing. We found a significantly increased risk of prostate cancer in the homozygote comparison [TT vs CC: odds ratio (OR) = 2.300, 95% confidence interval (95%CI) = 1.261-4.196, chi-square = 7.53, P = 0.007], heterozygote comparison (TC vs CC: OR = 1.667, 95%CI = 1.049-2.648, chi-square = 4.71, P = 0.030), dominant model (TT/TC vs CC: OR = 1.835, 95%CI = 1.197-2.815, chi-square = 7.81, P = 0.005), recessive model (TT vs TC/CC OR = 1.776, 95%CI = 1.023- 3.085, chi-square = 4.23, P = 0.041), and allele contrast (T vs C: OR = 1.625, 95%CI = 1.199-2.202, chi-square = 9.87, P = 0.002). These findings suggested that the c.1465C>T polymorphism of MDR1 may be risk factors for prostate cancer in Chinese men.

1. The objective of this study was to investigate the effect of concomitantly administered silymarin on the pharmacokinetics of talinolol, a typical substrate for P-glycoprotein (P-gp), in healthy Chinese volunteers and its association with a multidrug resistance 1 (MDR1) C3435T genetic polymorphism. 2. Eighteen healthy adult men (six MDR1 3435CC homozygotes, six MDR1 3435CT heterozygotes and six MDR1 3435TT homozygotes) were recruited in a two-phase, randomized, single-blind, crossover design. The pharmacokinetics of talinolol were measured after co-administration of placebo or 140 mg silymarin capsules three times daily for 14 days. Concentrations of talinolol in plasma were measured for up to 36 h after drug administration by liquid chromatography-mass spectrometry (HPLC-MS). 3. The peak plasma concentration (C(max)) of talinolol was significantly higher after silymarin administration as compared with placebo (p = 0.007). The area under the plasma concentration-time curve from zero to 36 h (AUC(0-36)) and AUC(0-infinity) of talinolol was increased by 36.2% +/- 33.2% and 36.5% +/- 37.9%, respectively, by silymarin co-administration. The oral clearance (CL/F) of talinolol was decreased by 23.1% +/- 16.6% (p < 0.001) during the silymarin-treated phase. No change in the time to peak concentration (t(max)) and the blood elimination half-life (t(1/2)) of talinolol was observed between the placebo- and silymarin-treated phases. 4. Co-administration of silymarin significantly increased the plasma concentration of talinolol in healthy volunteers.

Multidrug resistance 1 (MDR1) is a gene that expresses P-glycoprotein (P-gp), a drug transporter protein. Genetic polymorphisms ofMDR1can be associated with Sasang constitutions because Sasang constitutional medicine (SCM) prescribes different drugs according to different constitutions. A Questionnaire for Sasang Constitution Classification II (QSCC II) was used to diagnose Sasang constitutions. Two hundred and seven healthy people whose Sasang constitutions had been identified were tested. Genotype analyses, restriction fragment length polymorphism (RFLP) and pyrosequencing were used in MDR1 C1236T, and in MDR1 G2677T/A and C3435T, respectively. Significant differences inMDR1 C1236Tgenotypes were found between So-yangin and So-eumin.MDR1 G2677T/Agenotype also showed significant differences in allele distribution between So-yangin and Tae-eumin. So-yangin and So-eumin showed significant differences in the distribution of both 1236C-2677G-3435C and 1236T-2677G-3435T, haplotypes ofMDR1. The genetic polymorphism of theMDR1gene was thus shown to be an indicator that could distinguish So-yangin from other constitutions.

Udgivelsesdato: 2009 OBJECTIVE: Crohn's disease (CD) and ulcerative colitis (UC) are characterized by an impaired mucosal defence to normal constituents of the intestinal flora and a dysregulated inflammatory response. The purpose of the study was to investigate whether single nucleotide polymorphisms (SNPs) in genes involved in these processes were associated with CD and UC. MATERIAL AND METHODS: Allele frequencies of the cyclooxygenase 2 (COX-2/PTGS2/PGHS2) G-765C and breast cancer resistance protein (BCRP/ABCG2) C421A as well as allele and haplotype frequencies of multidrug resistance 1 (MDR1, ABCB1) SNPs G2677T/A, C3435T and G-rs3789243-A (intron 3) were assessed in a Danish case-control study comprising 373 CD and 541 UC patients and 796 healthy controls. RESULTS: Carriers of the homozygous COX-2 and MDR1 intron 3 variant had a relatively high risk of CD, odds ratio (95% CI) (OR (95% CI))=2.86 ((1.34-5.88) p=0.006) and 1.39 ((0.99-1.92) p=0.054), respectively, and for UC of 2.63 ((1.33-5.26) p=0.005) and 1.28 ((0.96-1.51) p=0.093), respectively, assuming complete dominance. No association was found for BCRP or other MDR1 SNPs, or for selected MDR1 haplotypes. No effect-modification of smoking habit at the time of diagnosis was found. CONCLUSIONS: An effect of the COX-2 polymorphism on both CD and UC was shown which is compatible with the presence of a recessive allele in linkage equilibrium with the SNP marker in the COX-2 gene. The polymorphism located in intron 3 of the MDR1 gene showed a weak association with CD, and a marginally suggestive association with UC.

It has been difficult to set an individualized therapeutic window of tacrolimus after organ transplantation, because of wide interindividual variation of responsiveness to immunosuppressive therapy. In this study, we examined the significance of multidrug resistance 1 (MDR1) in the peripheral blood cells by comparing the trough concentration of tacrolimus with the occurrence of acute cellular rejection (ACR) in retrospectively collected pediatric living-donor liver transplant patients, who were enrolled after obtaining written informed consent. No significant difference in the intraindividual variation in MDR1 mRNA expression in the peripheral blood cells was observed between postoperative days 3 and 7. The average trough concentration of tacrolimus during the 15-day postoperative period was significantly higher in the event-free patients than in those who experienced ACR (21 of 44 cases), and they had higher levels of blood MDR1 mRNA. In addition, the average trough concentration of tacrolimus significantly correlated with the logarithmically transformed MDR1 mRNA data from the blood cells in patients of both the event-free (r = 0.5406; P = 0.0077) and ACR (r = 0.4772; P = 0.0284). The cellular accumulation of [(14)C]tacrolimus in the peripheral blood mononuclear cells was 2-fold higher in mdr1a/1b-knockout mice than in wild-type mice (P = 0.0182). These results suggest that MDR1 in blood cells decreases the leukocytic concentration of tacrolimus, and it could be a useful marker to establish an individualized target concentration of tacrolimus to prevent ACR in pediatric patients after liver transplantation.

Background and Aims: We investigated the prevalence of this multidrug resistance 1 gene (MDR1) polymorphism in drug-responsive versus drug-resistant epilepsy patients treated with carbamazepine (CBZ), which is a substrate of this protein. Methods: We genotyped the C3435T variant of MDR1 in 97 patients treated with CBZ monotherapy who had been on stable doses for more than 1 month. Our control group included 174 healthy individuals. Plasma CBZ concentrations were also measured using fluorescence polarization immunoassay. Results: We could not demonstrate any statistically significant relationship with the genotypes among drug-resistant patients (n = 44). The frequency of the homozygous mutant (TT) genotype was 15% in drug-responsive patients, 11.3% in drug-resistant patients and 25.8% in the control group. We also did not observe any significant correlation between the presence of a specific allele and CBZ plasma level/dose index. Conclusion: Our study did not support any significant association between the MDR1 (C3435T) polymorphism and resistance to CBZ in epilepsy patients from Turkey.

To test the hypothesis that variations in the multidrug resistance-1 gene influence the response to statin treatment, 2 prevalent polymorphisms (G2677T/A and C3435T) were examined in 344 hypercholesterolemic patients treated with atorvastatin (10 mg). The C3435T polymorphism was significantly and independently associated with a smaller reduction in low-density lipoprotein cholesterol and with a larger increase in high-density lipoprotein cholesterol, relative to variant allele carriers, in a gender-specific manner. Also, haplotype determination combined with these polymorphisms identified a subgroup that showed a striking response to treatment, which was not defined by a single polymorphism.

WOS: 000215600200008, Aim: It was aimed to show the relationship between childhood asthma and C3435T multidrug resistance 1 gene polymorphism. Material and Method: Fifty eight children with asthma and 54 healthy children participated to the study. Chi-square and Fisher exact tests were used for statistical analysis. Results: Wild, heterozygous and homozygous polymorphism for multidrug resistance - 1 gene were found respectively in 12 (20.7%), 31 (53.4%), and 15 (25.9%) of children with asthma. In healthy children, wild, heterozygous, and homozygous polymorphisms were found respectively in 18 (33.3%), 28 (51.9%), and 8 (14.8%) participants. There was no statistical difference between asthmatic and healthy children in terms of multidrug resistance 1 gene polymorphism. Homozygous polymorphism was found higher in severe persistent group than moderate and mild persistent groups (p=0.001) and in girls than boys (p=0.001). Discussion: It may be said that the difference was resulted from severe persistent asthmatic patients. And this information helps clinicians to rank the patients in terms of asthma by looking multidrug resistance 1 gene when the patient was diagnosed as asthma. Hence, treatment of patients, especially with crucial degree may begin earlier and its long-term pursuance can be made. In addition, gender-specific treatment can be planned especially for female patients.

Commentary to:Co-suppression of MDR1 (multidrug resistance 1) and GCS（glucosylceramide synthase）restores sensitivity to multidrug resistance breast cancer cells by RNA interference (RNAi)Xiaofang Zhang, Juan Li, Zhengang Qiu, Peng Gao, Xiaojuan Wu, Genyin Zhou

13107 Background: To test the hypotheses of whether the relative mRNA expression of the thymidylate synthase (TS) gene and multidrug resistance 1 (MDR1) gene are associated with response to chemotherapy with S-1 in metastatic colorectal cancer. Methods: Eighteen patients with progressive stage IV CRC were treated with S-1 twice daily (BSA = 1.5 m2, 60 mg/day) for 28 days, followed by a 2-week period rest. cDNA was derived from frozen tumor specimens to determine TS and MDR1 mRNA expression relative to the internal reference gene GAPDH using fluorescence-based, real-time reverse transcriptase polymerase chain reaction (Taqman) system. Results: The median TS gene expression level from 18 CRC tumors was 0.94 × 10(−3) (minimum expression, 0.15 × 10(−3); maximum expression, 8.0 × 10(−3)), and the median MDR1 gene expression level was 7.75 × 10(−3) (minimum, 0.83; maximum, 41.5 × 10(−3)). The gene expression cutoff values for chemotherapy nonresponse were 1.0 x 10(-3) for TS and 10.0 × 10(−3) for MDR1. The response rate for patients with TS < or = 1.0 × 10(−3) (10 of 18 patients) was 60% (6/10), compared with 0% (0/8) for patients with TS greater than 1.0 × 10(−3) (P = 0.013). Patients with MDR1 expression < or = 10.0 × 10(−3) (13 of 18 patients) had a response rate of 46% (6/13), compared with 0% (0/5) for patients with MDR1 expression greater than 10.0 × 10(−3) (P = 0.11). Regarding the combination of TS and MDR1 Expression, low TS and MDR1 expression levels were detected in 8 (44%) of the patients, and 10 patients (56%) had a high TS and/or MDR1 expression level. The response rate was 75% (6/8) for the low TS and MDR1 expressors and 0% (0/10) for the high TS and/or MDR1 expressors (P = 0.001). Conclusions: These data suggest that intratumoral TS and MDR1 mRNA expression levels are independent predictive markers of response to S-1 chemotherapy in metastatic colorectal cancer. No significant financial relationships to disclose.

6550 Background: Multidrug resistance (MDR) is one of the important mechanisms of treatment failure of acute myeloid leukemia (AML). Recently, MDR-1 gene single nucleotide polymorphism (SNP) has be...