ABCMdb

ABCB1 p.Asn183Ser

Predicted by SNAP2:	A: N (57%), C: N (66%), D: D (53%), E: N (61%), F: D (59%), G: N (53%), H: N (78%), I: D (59%), K: N (66%), L: D (59%), M: D (66%), P: D (66%), Q: N (82%), R: N (57%), S: N (82%), T: N (61%), V: N (53%), W: D (80%), Y: N (53%),
Predicted by PROVEAN:	A: D, C: D, D: D, E: D, F: D, G: D, H: N, I: D, K: D, L: D, M: D, P: D, Q: N, R: D, S: N, T: D, V: D, W: D, Y: D,

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[hide] Mechanisms of resistance to anticancer drugs: the ... Pharmacogenomics. 2005 Mar;6(2):115-38. Lepper ER, Nooter K, Verweij J, Acharya MR, Figg WD, Sparreboom A
Mechanisms of resistance to anticancer drugs: the role of the polymorphic ABC transporters ABCB1 and ABCG2.
Pharmacogenomics. 2005 Mar;6(2):115-38., [PMID:15882131]

Abstract [show]
ATP-binding cassette (ABC) genes play a role in the resistance of malignant cells to anticancer agents. The ABC gene products, including ABCB1 (P-glycoprotein) and ABCG2 (breast cancer-resistance protein [BCRP], mitoxantrone-resistance protein [MXR], or ABC transporter in placenta [ABCP]), are also known to influence oral absorption and disposition of a wide variety of drugs. As a result, the expression levels of these proteins in humans have important consequences for an individual's susceptibility to certain drug-induced side effects, interactions, and treatment efficacy. Naturally occurring variants in ABC transporter genes have been identified that might affect the function and expression of the protein. This review focuses on recent advances in the pharmacogenetics of the ABC transporters ABCB1 and ABCG2, and discusses potential implications of genetic variants for the chemotherapeutic treatment of cancer.

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106 Nonetheless, the association of the C3435T polymorphism with Table 2. Summary of common genetic variants in the ABCB1 gene cDNA position* Region‡ Wild-type allele Variant allele Amino acid Change§ -274 Intron -1 G A -223 Intron -1 C T -146 Intron -1 T C -60 Intron -1 A T -41 Intron -1 A G Non-coding -241 Exon 1 G A Non-coding -145 Exon 1 C G Non-coding -129 Exon 1 T C Non-coding -43 Exon 1 A G Non-coding +140 Intron 1 C A +237 Intron 1 G A -4 Exon 2 C T Non-coding -1 Exon 2 G A Non-coding 61 Exon 2 A G 21 Asn to Asp -8 Intron 3 C G 266 Exon 4 T C 89 Met to Thr 307 Exon 5 T C 103 Phe to Leu -25 Intron 4 G T +139 Intron 6 C T +145 Intron 6 C T 548 Exon 7 A G 183 Asn to Ser 729 Exon 8 A G 243 Syn 781 Exon 8 A G 261 Ile to Val -44 Intron 9 A G -41 Intron 10 T G 1199 Exon 11 G A 400 Ser to Asn -4 Intron 11 G A 1236¶ Exon 12 C T 412 Syn 1308 Exon 12 A G 436 Syn +17 Intron 12 G A +44 Intron 12 C T 1474 Exon 13 C T 492 Arg to Cys +24 Intron 13 C T 1617 Exon 14 C T 539 Syn +38 Intron 14 A G +38 Intron 15 G A 1985 Exon 16 T G 662 Leu to Arg 2005 Exon 16 C T 669 Arg to Cys -27 Intron 17 A G +8 Intron 20 C G *cDNA numbers are relative to the ATG site and based on the cDNA sequence from GenBank accession number M14758 with an A as the reference at position 43. Login to comment

[hide] Genetic polymorphisms of ATP-binding cassette tran... Expert Opin Pharmacother. 2005 Nov;6(14):2455-73. Sakurai A, Tamura A, Onishi Y, Ishikawa T
Genetic polymorphisms of ATP-binding cassette transporters ABCB1 and ABCG2: therapeutic implications.
Expert Opin Pharmacother. 2005 Nov;6(14):2455-73., [PMID:16259577]

Abstract [show]
Pharmacogenomics, the study of the influence of genetic factors on drug action, is increasingly important for predicting pharmacokinetics profiles and/or adverse reactions to drugs. Drug transporters, as well as drug metabolism play pivotal roles in determining the pharmacokinetic profiles of drugs and their overall pharmacological effects. There is an increasing number of reports addressing genetic polymorphisms of drug transporters. However, information regarding the functional impact of genetic polymorphisms in drug transporter genes is still limited. Detailed functional analysis in vitro may provide clear insight into the biochemical and therapeutic significance of genetic polymorphisms. This review addresses functional aspects of the genetic polymorphisms of human ATP-binding cassette transporters, ABCB1 and ABCG2, which are critically involved in the pharmacokinetics of drugs.

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115 For this purpose, ABCB1 cDNA cloned from a human liver cDNA library was prepared, and several variant forms (i.e., N183S, S400N, R492C, R669C, I849M, A893T, M986V, A999T, P1051A and G1063A) were generated by site-directed mutagenesis. Login to comment
124 The variant forms (i.e., N183S, S400N, R492C, R669C, I849M, A893T, M986V, A999T, P1051A and G1063A), as well as the wild type, of ABCB1 exhibited the verapamil-enhanced ATPase activity. Login to comment
129 N21D M89T N44S H2N F103L E108K N183S G185V I261V S400N R492C A599T L662R R669C V801M A893S/T I829V I849M M986V A999T G1063A P1051A Q1107P W1108R I1145M S1141T V1251I T1256K COOH ATP-binding site ATP-binding site EXTRACELLULAR INTRACELLULAR A80E Figure 2. Login to comment
139 The I849M and A999T variants had Km values lower than that of wild-type ABCB1, whereas the Km value of the N183S variant was higher. Login to comment

[hide] High-speed screening of human ATP-binding cassette... Methods Enzymol. 2005;400:485-510. Ishikawa T, Sakurai A, Kanamori Y, Nagakura M, Hirano H, Takarada Y, Yamada K, Fukushima K, Kitajima M
High-speed screening of human ATP-binding cassette transporter function and genetic polymorphisms: new strategies in pharmacogenomics.
Methods Enzymol. 2005;400:485-510., [PMID:16399366]

Abstract [show]
Drug transporters represent an important mechanism in cellular uptake and efflux of drugs and their metabolites. Hitherto a variety of drug transporter genes have been cloned and classified into either solute carriers or ATP-binding cassette (ABC) transporters. Such drug transporters are expressed in various tissues such as the intestine, brain, liver, kidney, and, importantly, cancer cells, where they play critical roles in the absorption, distribution, and excretion of drugs. We developed high-speed functional screening and quantitative structure-activity relationship analysis methods to study the substrate specificity of ABC transporters and to evaluate the effect of genetic polymorphisms on their function. These methods would provide powerful and practical tools for screening synthetic and natural compounds, and the deduced data can be applied to the molecular design of new drugs. Furthermore, we demonstrate a new "SNP array" method to detect genetic polymorphisms of ABC transporters in human samples.

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167 For this purpose, we have prepared several variant forms (i.e., N183S, S400N, R492C, R669C, I849M, A893T, M986V, A999T, P1051A, and G1063A) by site‐ directed mutagenesis. Login to comment

[hide] Role of pharmacogenetics of ATP-binding cassette t... Pharmacol Ther. 2006 Nov;112(2):457-73. Cascorbi I
Role of pharmacogenetics of ATP-binding cassette transporters in the pharmacokinetics of drugs.
Pharmacol Ther. 2006 Nov;112(2):457-73., [PMID:16766035]

Abstract [show]
Interindividual differences of drug response are an important cause of treatment failures and adverse drug reactions. The identification of polymorphisms explaining distinct phenotypes of drug metabolizing enzymes contributed in part to the understanding of individual variations of drug plasma levels. However, bioavailability also depends on a major extent from the expression and activity of drug transport across biomembranes. In particular efflux transporters of the ATP-binding cassette (ABC) family such as ABCB1 (P-glycoprotein, P-gp), the ABCC (multidrug resistance-related protein, MRP) family and ABCG2 (breast cancer resistance protein, BCRP) have been identified as major determinants of chemoresistance in tumor cells. They are expressed in the apical membranes of many barrier tissue such as the intestine, liver, blood-brain barrier, kidney, placenta, testis and in lymphocytes, thus contributing to plasma, liquor, but also intracellular drug disposition. Since expression and function exhibit a broad variability, it was hypothesized that hereditary variances in the genes of membrane transporters could explain at least in part interindividual differences of pharmacokinetics and clinical outcome of a variety of drugs. This review focuses on the functional significance of single nucleotide polymorphisms (SNP) of ABCB1, ABCC1, ABCC2, and ABCG2 in in vitro systems, in vivo tissues and drug disposition, as well as on the clinical outcome of major indications.

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761 0.09d c. 61 A>G N21D 0.11d IVS 5-35 G>C intronic 0.006c IVS 5-25 G>T intronic 0.16c IVS 6+139 C>T intronic 0.37d c. 548 A>G N183S 0.01e c. 1199 G>A S400N 0.05d c. 1236 C>T synonymous 0.41d IVS 12+44 C>T intronic 0.05d c. 1474 C>T R492C 0.01e IVS 17-76 T>A intronic 0.46d IVS 17+137 A>G intronic 0.006c c. 2650 C>T synonymous 0.03e c. 2677 G>T/A A893S/T 0.42d /0.02d c. 2956 A>G M986V 0.005b c. 3320 A>C Q1107P 0.002d c. 3396 C>T synonymous 0.03c c. 3421 T>A S1141T 0.00c c. 3435 C>T synonymous 0.54e c. 4030 G >C synonymous 0.005b c. 4036 A>G synonymous 0.30b a Taniguchi et al. (2003). Login to comment

[hide] Clinical pharmacogenetics and potential applicatio... Curr Drug Metab. 2008 Oct;9(8):738-84. Zhou SF, Di YM, Chan E, Du YM, Chow VD, Xue CC, Lai X, Wang JC, Li CG, Tian M, Duan W
Clinical pharmacogenetics and potential application in personalized medicine.
Curr Drug Metab. 2008 Oct;9(8):738-84., [PMID:18855611]

Abstract [show]
The current 'fixed-dosage strategy' approach to medicine, means there is much inter-individual variation in drug response. Pharmacogenetics is the study of how inter-individual variations in the DNA sequence of specific genes affect drug responses. This article will highlight current pharmacogenetic knowledge on important drug metabolizing enzymes, drug transporters and drug targets to understand interindividual variability in drug clearance and responses in clinical practice and potential use in personalized medicine. Polymorphisms in the cytochrome P450 (CYP) family may have had the most impact on the fate of pharmaceutical drugs. CYP2D6, CYP2C19 and CYP2C9 gene polymorphisms and gene duplications account for the most frequent variations in phase I metabolism of drugs since nearly 80% of drugs in use today are metabolised by these enzymes. Approximately 5% of Europeans and 1% of Asians lack CYP2D6 activity, and these individuals are known as poor metabolizers. CYP2C9 is another clinically significant drug metabolising enzyme that demonstrates genetic variants. Studies into CYP2C9 polymorphism have highlighted the importance of the CYP2C9*2 and CYP2C9*3 alleles. Extensive polymorphism also occurs in a majority of Phase II drug metabolizing enzymes. One of the most important polymorphisms is thiopurine S-methyl transferases (TPMT) that catalyzes the S-methylation of thiopurine drugs. With respect to drug transport polymorphism, the most extensively studied drug transporter is P-glycoprotein (P-gp/MDR1), but the current data on the clinical impact is limited. Polymorphisms in drug transporters may change drug's distribution, excretion and response. Recent advances in molecular research have revealed many of the genes that encode drug targets demonstrate genetic polymorphism. These variations, in many cases, have altered the targets sensitivity to the specific drug molecule and thus have a profound effect on drug efficacy and toxicity. For example, the beta (2)-adrenoreceptor, which is encoded by the ADRB2 gene, illustrates a clinically significant genetic variation in drug targets. The variable number tandem repeat polymorphisms in serotonin transporter (SERT/SLC6A4) gene are associated with response to antidepressants. The distribution of the common variant alleles of genes that encode drug metabolizing enzymes, drug transporters and drug targets has been found to vary among different populations. The promise of pharmacogenetics lies in its potential to identify the right drug at the right dose for the right individual. Drugs with a narrow therapeutic index are thought to benefit more from pharmacogenetic studies. For example, warfarin serves as a good practical example of how pharmacogenetics can be utilized prior to commencement of therapy in order to achieve maximum efficacy and minimum toxicity. As such, pharmacogenetics has the potential to achieve optimal quality use of medicines, and to improve the efficacy and safety of both prospective and licensed drugs.

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532 Nucleotide change rs number Amino acid change 49T>C rs28381804 F17L 61A>G rs61615398; rs9282564 N21D 131A>G rs1202183 N44S 178A>C rs41315618 I60L 239C>A rs9282565 A80E 266T>C Rs35810889 M89T 431T>C rs61607171 I144T 502G>A rs61122623 V168I 548A>G rs60419673 N183S 554G>T rs1128501 G185V 781A>G rs36008564 I261V 1199G>A rs2229109 S400N 1696G>A rs28381902 E566K 1777C>T rs28381914 R593C 1778G>A rs56107566 R593H 1795G>A rs2235036 A599T 1837G>T rs57001392 D613Y 1985T>G rs61762047 L662R 2005C>T rs35023033 R669C 2207A>T rs41316450 I736K 2398G>A rs41305517 D800N 2401G>A rs2235039 V801M 2485A>G rs2032581 I829V 2506A>G rs28381967 I836V 2547A>G rs36105130 I849M 2677T>A/G rs2032582 S893A/T 2975G>A rs56849127 S992N 3151C>G rs28401798 P1051A 3188G>C rs2707944 G1063A 3262G>A rs57521326 D1088N 3295A>G rs41309225 K1099E 3320A>C rs55852620 Q1107P 3322T>C rs35730308 W1108R 3410G>T rs41309228 S1137I 3421T>A rs2229107 S1141T 3502A>G rs59241388 K1168E 3669A>T rs41309231 E1223D 3751G>A rs28364274 V1251I 3767C>A r35721439 T1256K Data are from NCBI dbSNP (access date: 2 August 2008). Login to comment

[hide] Pharmacogenetics of ATP-binding cassette transport... Methods Mol Biol. 2010;596:95-121. Cascorbi I, Haenisch S
Pharmacogenetics of ATP-binding cassette transporters and clinical implications.
Methods Mol Biol. 2010;596:95-121., [PMID:19949922]

Abstract [show]
Drug resistance is a severe limitation of chemotherapy of various malignancies. In particular efflux transporters of the ATP-binding cassette family such as ABCB1 (P-glycoprotein), the ABCC (multidrug resistance-associated protein) family, and ABCG2 (breast cancer resistance protein) have been identified as major determinants of chemoresistance in tumor cells. Bioavailability depends not only on the activity of drug metabolizing enzymes but also to a major extent on the activity of drug transport across biomembranes. They are expressed in the apical membranes of many barrier tissues such as the intestine, liver, blood-brain barrier, kidney, placenta, testis, and in lymphocytes, thus contributing to plasma, liquor, but also intracellular drug disposition. Since expression and function exhibit a broad variability, it was hypothesized that hereditary variances in the genes of membrane transporters could explain at least in part interindividual differences of pharmacokinetics of a variety of anticancer drugs and many others contributing to the clinical outcome of certain leukemias and further malignancies.

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52 Functional Significance of ABCB1 SNPs Table6.3 Frequency of ABCB1 genetic variants in Caucasians, position on DNA, putative effect, and frequencies (134) Position Amino acid or effect Frequency of the variant allele 5'-Flanking -2903 T>C 0.02a 5'-Flanking -2410 T>C 0.10a 5'-Flanking -2352 G>A 0.28a 5'-Flanking -1910 T>C 0.10a 5'-Flanking -1717 T>C 0.02a 5'-Flanking -1325 A>G 0.02a 5'-Flanking -934 A>G 0.10a 5'-Flanking -692 T>C 0.10a 5'-Flanking -41 A>G 0.09b IVS 1a -145 C>G 0.02b IVS 1b -129 T>C 0.06b IVS 1b 12 T>C 0.06c IVS 2 -1 G>A 0.09d c. 61 A>G N21D 0.11d IVS 5 -35 G>C Intronic 0.006c IVS 5 -25 G>T Intronic 0.16c IVS 6 +139 C>T Intronic 0.37d c. 548 A>G N183S 0.01e c. 1199 G>A S400N 0.05d c. 1236 C>T Synonymous 0.41d IVS 12 +44 C>T Intronic 0.05d c. 1474 C>T R492C 0.01e IVS 17 -76 T>A Intronic 0.46d IVS 17 +137 A>G Intronic 0.006c c. 2650 C>T Synonymous 0.03e c. 2677 G>T/A A893S/T 0.42d /0.02d c. 2956 A>G M986V 0.005b c. 3320 A>C Q1107P 0.002d c. 3396 C>T Synonymous 0.03c c. 3421 T>A S1141T 0.00c c. 3435 C>T Synonymous 0.54d c. 4030 Synonymous 0.005b c. 4036 Synonymous 0.30b References: a [42], b [26], c [25], d [28], e [23] with lower activity or expression in Caucasians. Login to comment

[hide] Biochemical, cellular, and pharmacological aspects... Annu Rev Pharmacol Toxicol. 1999;39:361-98. Ambudkar SV, Dey S, Hrycyna CA, Ramachandra M, Pastan I, Gottesman MM
Biochemical, cellular, and pharmacological aspects of the multidrug transporter.
Annu Rev Pharmacol Toxicol. 1999;39:361-98., [PMID:10331089]

Abstract [show]
Considerable evidence has accumulated indicating that the multidrug transporter or P-glycoprotein plays a role in the development of simultaneous resistance to multiple cytotoxic drugs in cancer cells. In recent years, various approaches such as mutational analyses and biochemical and pharmacological characterization have yielded significant information about the relationship of structure and function of P-glycoprotein. However, there is still considerable controversy about the mechanism of action of this efflux pump and its function in normal cells. This review summarizes current research on the structure-function analysis of P-glycoprotein, its mechanism of action, and facts and speculations about its normal physiological role.

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47 Table 1 List of mutations in human, mouse, and hamster P-glycoproteins that affect substrate specificitya aa mutation Region Sourceb Reference H61R, F, K, M, W, Y TM 1 Human MDR1 149, 150 ABC20c G64R TM 1 Human MDR1 150 L65R TM 1 Human MDR1 150 aa78-97 EC 1 Human MDR1 151 Q128Hd TM 2 Mouse mdr3 152 R138H IC 1 Mouse mdr3 152 Q139H, R IC 1 Mouse mdr3 152 Q141V IC 1 Human MDR1 15319, Q145H IC 1 Mouse mdr3 152 E155G, K IC 1 Mouse mdr3 152 F159I IC 1 Mouse mdr3 152 D174G IC 1 Mouse mdr3 152 S176G, P IC 1 Mouse mdr3 152 K177I IC 1 Mouse mdr3 152 N179S IC 1 Mouse mdr3 152 N183S/G185V IC 1 Human MDR1 154 G183D IC 1 Mouse mdr3 152 G185V IC 1 Human MDR1 155-157 G187V IC 1 Human MDR1 153 A192T TM 3 Mouse mdr3 152 F204S EC 2 Mouse mdr3 152 W208G EC 2 Mouse mdr3 152 K209E EC 2 Mouse mdr3 152 L210I TM 4 Mouse mdr3 152 T211P TM 4 Mouse mdr3 152 I214T TM 4 Mouse mdr3 152 P223A TM 4 Human MDR1 158 G288V IC 2 Human MDR1 153 I299M, T319S, L322I, TM 5, EC3, Human MDR1 159 G324K, S351N IC 3 F335A TM 6 Human MDR1 19 F335 TM 6 Human MDR1 160 V338A TM 6 Human MDR1 161 G338A, A339P TM 6 Hamster PGY1 162, 163 A339P TM 6 Hamster PGY1 163 G341V TM 6 Human MDR1 161 K536R, Q N-NBD Human MDR1 164 ERGA → DKGT N-NBD Mouse mdr3 165 aa 522-525 T578C N-NBD Mouse mdr3 165 (Continued) G830V IC 4 Human MDR1 P866A TM 10 Human MDR1 158 F934A TM 11 Mouse mdr3 166 G935A TM 11 Mouse mdr3 166 I936A TM 11 Mouse mdr3 166 F938A TM 11 Mouse mdr3 166 S939A TM 11 Mouse mdr3 166 S939F TM 11 Mouse mdr3 167, 168 S941F TM 11 Mouse mdr1 167, 168 T941A TM 11 Mouse mdr3 166 Q942A TM 11 Mouse mdr3 166 A943G TM 11 Mouse mdr3 166 Y946A TM 11 Mouse mdr3 166 S948A TM 11 Mouse mdr3 166 Y949A TM 11 Mouse mdr3 166 C952A TM 11 Mouse mdr3 166 F953A TM 11 Mouse mdr3 166 F983A TM 12 Human MDR1 169 L975A, V981A, F983A TM 12 Human MDR1 169 M986A, V988A, Q990A, TM 12 Human MDR1 169 V991A V981A, F983A TM 12 Human MDR1 169 L975A, F983A TM 12 Human MDR1 169 L975A, V981A TM 12 Human MDR1 169 F978A TM 12 Human MDR1 19 a aa,amino acid; EC, extracellular loop; IC, intracellular loop; TM,transmembrane domain; NBD, nucleotide binding/utilization domain. Login to comment

[hide] Identification of functionally variant MDR1 allele... Clin Pharmacol Ther. 2001 Aug;70(2):189-99. Kim RB, Leake BF, Choo EF, Dresser GK, Kubba SV, Schwarz UI, Taylor A, Xie HG, McKinsey J, Zhou S, Lan LB, Schuetz JD, Schuetz EG, Wilkinson GR
Identification of functionally variant MDR1 alleles among European Americans and African Americans.
Clin Pharmacol Ther. 2001 Aug;70(2):189-99., [PMID:11503014]

Abstract [show]
MDR1 (P-glycoprotein) is an important factor in the disposition of many drugs, and the involved processes often exhibit considerable interindividual variability that may be genetically determined. Single-strand conformational polymorphism analysis and direct sequencing of exonic MDR1 deoxyribonucleic acid from 37 healthy European American and 23 healthy African American subjects identified 10 single nucleotide polymorphisms (SNPs), including 6 nonsynonymous variants, occurring in various allelic combinations. Population frequencies of the 15 identified alleles varied according to racial background. Two synonymous SNPs (C1236T in exon 12 and C3435T in exon 26) and a nonsynonymous SNP (G2677T, Ala893Ser) in exon 21 were found to be linked (MDR1*2 ) and occurred in 62% of European Americans and 13% of African Americans. In vitro expression of MDR1 encoding Ala893 (MDR1*1 ) or a site-directed Ser893 mutation (MDR1*2 ) indicated enhanced efflux of digoxin by cells expressing the MDR1-Ser893 variant. In vivo functional relevance of this SNP was assessed with the known P-glycoprotein drug substrate fexofenadine as a probe of the transporter's activity. In humans, MDR1*1 and MDR1*2 variants were associated with differences in fexofenadine levels, consistent with the in vitro data, with the area under the plasma level-time curve being almost 40% greater in the *1/*1 genotype compared with the *2/*2 and the *1/*2 heterozygotes having an intermediate value, suggesting enhanced in vivo P-glycoprotein activity among subjects with the MDR1*2 allele. Thus allelic variation in MDR1 is more common than previously recognized and involves multiple SNPs whose allelic frequencies vary between populations, and some of these SNPs are associated with altered P-glycoprotein function.

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104 In addition, a number of detected SNPs, such as A548G (Asn183Ser), C1472T (Arg492Cys), and T3421A (Ser1141Thr), represented previously undescribed nonsynonymous SNPs. Login to comment

[hide] Genetic polymorphisms of the human MDR1 drug trans... Annu Rev Pharmacol Toxicol. 2003;43:285-307. Epub 2002 Jan 10. Schwab M, Eichelbaum M, Fromm MF
Genetic polymorphisms of the human MDR1 drug transporter.
Annu Rev Pharmacol Toxicol. 2003;43:285-307. Epub 2002 Jan 10., [PMID:12359865]

Abstract [show]
P-glycoprotein is an ATP-dependent efflux pump that contributes to the protection of the body from environmental toxins. It transports a huge variety of structurally diverse compounds. P-glycoprotein is involved in limiting absorption of xenobiotics from the gut lumen, in protection of sensitive tissues (brain, fetus, testis), and in biliary and urinary excretion of its substrates. P-glycoprotein can be inhibited or induced by xenobiotics, thereby contributing to variable drug disposition and drug interactions. Recently, several SNPs have been identified in the MDR1 gene, some of which can affect P-glycoprotein expression and function. Potential implications of MDR1 polymorphisms for drug disposition, drug effects, and disease risk are discussed.

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54 Further SNPs of the MDR1 gene were identified in Asians, an A to G transversion 41 bases upstream from the initial position of exon 1a (A-41aG) and a C to G transversion at -145 in exon 1a (C-145G) (28), as well as three nonsynonymous mutations A548G (Asn183Ser), C1474T (Arg492Cys), and T3421A (Ser1141Thr) in different ethnic populations (29, 30). Login to comment
60 In a Northern Italian population, the extent of linkage disequilibrium TABLE 2 Summary of MDR1 genetic variants in different ethnic groups Location Position Allele Effect Reference promotor 5 flanking/-41a A (28) G exon 1a exon 1a/-145 C (28) G exon 1b exon 1b/-129 T (25, 33) C intron 1 exon 2/-4 C (29) T intron 1 exon 2/-1 G initiation of translation (25, 27, 29) A exon 2 exon 2/61 A Asn21Asp (25-27, 29) G intron 4 exon 5/-35 G (25) C intron 4 exon 5/-25 G (25) T exon 5 exon 5/307 T Phe103Leu (25) C intron 6 exon 6/+139 C (25, 27) T intron 6 exon 6/+145 C (25) T exon 7 exon 7/548 A Asn183Ser (29) G exon 11 exon 11/1199 G Ser400Asn (25, 27, 29) A exon 12 exon 12/1236 C wobble (23, 25, 27, 29) T (Gly412Gly) intron 12 exon 12/+44 C (25, 27) T exon 13 exon 13/1474 C Arg492Cys (29) T intron 16 exon 17/-76 T (25, 27) A intron 17 exon 17/137 A (25) G exon 21 exon 21/2650 C wobble (29) T (Leu884Leu) (Continued ) TABLE 2 (Continued) Location Position Allele Effect Reference exon 21 exon 21/2677 G (22, 23, 27, 29) T Ala893Ser A Ala893Thr exon 24 exon 24/2956 A Met986Val (33) G exon 24 exon 24/2995 G Ala999Thr (22) A exon 26 exon 26/3320 A Gln1107Pro (27) C exon 26 exon 26/3396 C wobble (25) T exon 26 exon 26/3421 T Ser1141Thr (29, 30) A exon 26 exon 26/3435 C wobble (23, 25, 29) T (Ile1145Ile) exon 28 exon 28/4030 G (33) C exon 28 exon 28/4036 A (23, 33) G The positions of the polymorphisms correspond to positions of MDR1 cDNA with the first base of the ATG start codon set to 1 (GenBank accession # M14758). Login to comment

[hide] MDR1 genotype-related pharmacokinetics and pharmac... Biol Pharm Bull. 2002 Nov;25(11):1391-400. Sakaeda T, Nakamura T, Okumura K
MDR1 genotype-related pharmacokinetics and pharmacodynamics.
Biol Pharm Bull. 2002 Nov;25(11):1391-400., [PMID:12419946]

Abstract [show]
The multidrug resistant transporter MDR1/P-glycoprotein, the gene product of MDR1, is a glycosylated membrane protein of 170 kDa, belonging to the ATP-binding cassette superfamily of membrane transporters. MDR1 acts as an energy-dependent efflux pump that exports its substrates out of cells. MDR1 was originally isolated from resistant tumor cells as part of the mechanism of multidrug resistance, but over the last decade, it has been elucidated that human MDR1 is also expressed throughout the body to confer intrinsic resistance to the tissues by exporting unnecessary or toxic exogeneous substances or metabolites. A number of structurally unrelated drugs are substrates for MDR1, and MDR1 and other transporters are recognized as an important class of proteins for regulating pharmacokinetics and pharmacodynamics. In 2000, Hoffmeyer et al. performed a systemic screening for MDR1 polymorphisms and detected 15 single nucleotide polymorphisms (SNPs). They also indicated that a polymorphism in exon 26 at position 3435 (C3435T), a silent mutation, affected the expression level of MDR1 protein in duodenum, and thereby the intestinal absorption of digoxin. To date, the genotype frequencies of C3435T have been investigated extensively using a larger population and interethnic difference has been elucidated, and a total of 28 SNPs have been found at 27 positions on the MDR1 gene. Clinical studies on MDR1 genotype-related MDR1 expression and pharmacokinetics have also been performed around the world; however, results were not always consistent with Hoffmeyer's report. In this review, published reports are summarized for the future individualization of pharmacotherapy based on MDR1 genotyping. In addition, recent investigations have raised the possibility that MDR1 and related transporters play a fundamental role in regulating apoptosis and immunology, and in fact, there are reports of MDR1-related susceptibility to inflammatory bowel disease, HIV infection and renal cell carcinoma. Herein, these issues are also summarized, and the current status of the knowledge in the area of pharmacogenomics of other transporters is briefly introduced.

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52 Kim et al. defined 15 alleles based on the frequencies of 11 polymorphisms of C-4T (noncoding), G-1A (noncoding), A61G (Asn21Asp), A548G (Asn183Ser), G1199A (Ser400Asn), C1236T (silent), C1474T (Arg492Cys), C2650T (silent), G2677T (Ala893Ser), T3421A (Ser1141Thr) and C3435T (silent).54) Six of 11 accompanied an amino acid change, and the others were conservative mutations. Login to comment
56 In 2001, Hitzl et al. also indicated that healthy Caucasian subjects with T/T3435 had a more decreased efflux of rhodamine from CD56ϩ NK cells and a lower MDR1 mRNA expression in leukocytes than those with C/C3435 .65) In renal tissues, the C3435T polymorphism is reported to be associated with reduced MDR1 expression.31) However, Tanabe et al. suggested that C3435T had no effect on the placental MDR1 expression based on 89 subjects and Western blotting.53) We determined MDR1 mRNA levels in biopsy specimens of the duodenum obtained from 13 healthy Japanese subjects by real time quantitative RT-PCR and found that MDR1 mRNA expression was higher in T/T3435 than C/C3435 or C/T3435 (Fig. 1).66) The discrepancies between the reports might be ex- November 2002 1393 Table 2. Summary of Genetic Polymorphisms in MDR1 Position Location Effect A1a/-41G Intron Noncoding C-145G Exon 1a Noncoding T-129C (T12C) Exon 1b Noncoding C-4T Exon 2 Noncoding G-1A Exon 2 Noncoding A61G Exon 2 Asn21Asp G5/-25T Intron G5/-35C Intron T307C Exon 5 Phe103Leu C6/ϩ139T Intron A548G Exon 7 Asn183Ser G1199A Exon 11 Ser400Asn C1236T Exon 12 Silent C12/ϩ44T Intron C1474T Exon 13 Arg492Cys T17/-76A Intron A17/ϩ137G Intron C2650T Exon 21 Silent G2677(A,T) Exon 21 Ala893Thr (G2677A) Ala893Ser (G2677T) A2956G Exon 24 Met986Val G2995A Exon 24 Ala999Thr A3320C Exon 26 Gln1107Pro C3396T Exon 26 Silent T3421A Exon 26 Ser1141Thr C3435T Exon 26 Silent G4030C Exon 28 Silent A4036G Exon 28 Silent This list was based on the literature (refs. 49-54). Login to comment

[hide] Pharmacogenetics of MDR1 and its impact on the pha... Pharmacogenomics. 2003 Jul;4(4):397-410. Sakaeda T, Nakamura T, Okumura K
Pharmacogenetics of MDR1 and its impact on the pharmacokinetics and pharmacodynamics of drugs.
Pharmacogenomics. 2003 Jul;4(4):397-410., [PMID:12831320]

Abstract [show]
The multi-drug resistant transporter MDR1/P-glycoprotein, the gene product of MDR1, is a glycosylated membrane protein of 170 kDa, belonging to the ATP-binding cassette (ABC) superfamily of membrane transporters. MDR1 was originally isolated from resistant tumor cells as part of the mechanism of multi-drug resistance, but over the last decade, it has been elucidated that human MDR1 is also expressed throughout the body to confer intrinsic resistance to the tissues by exporting unnecessary or toxic exogeneous substances or metabolites. A number of various types of structurally unrelated drugs are substrates for MDR1, and MDR1 and other transporters are recognized as an important class of proteins for regulating pharmacokinetics and pharmacodynamics. In 2000, Hoffmeyer et al. performed a systemic screening for MDR1 polymorphisms and indicated that a single nucleotide polymorphism (SNP), C3435T in exon 26, which caused no amino acid change, was associated with the duodenal expression of MDR1 and thereby the plasma concentrations of digoxin after oral administration. Interethnic differences in genotype frequencies of C3435T have been clarified, and, at present, a total of 28 SNPs have been found at 27 positions on the MDR1 gene. Clinical studies on the effects of C3435T on MDR1 expression and function in the tissues, and also on the pharmacokinetics and pharmacodynamics have been performed around the world; however, there are still discrepancies in the results, suggesting that the haplotype analysis of the gene should be included instead of SNP detection, and the design of clinical trials must be carefully planned to avoid misinterpretations. A polymorphism of C3435T is also reported to be a risk factor for a certain class of diseases such as the inflammatory bowel diseases, Parkinson's disease and renal epithelial tumor, and this might also be explained by the effects on MDR1 expression and function. In this review, the latest reports are summarized for the future individualization of pharmacotherapy based on MDR1 genotyping.

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75 Position Location Effect A1a/-41G Intron Non-coding C-145G Exon 1a Non-coding T-129C (T12C) Exon 1b Non-coding C-4T Exon 2 Non-coding G-1A Exon 2 Non-coding A61G Exon 2 Asn21Asp G5/-25T Intron G5/-35C Intron T307C Exon 5 Phe103Leu C6/+139T Intron A548G Exon 7 Asn183Ser G1199A Exon 11 Ser400Asn C1236T Exon 12 Silent C12/+44T Intron C1474T Exon 13 Arg492Cys T17/-76A Intron A17/+137G Intron C2650T Exon 21 Silent G2677(A,T) Exon 21 Ala893Thr (G2677A) Ala893Ser (G2677T) A2956G Exon 24 Met986Val G2995A Exon 24 Ala999Thr A3320C Exon 26 Gln1107Pro C3396T Exon 26 Silent T3421A Exon 26 Ser1141Thr C3435T Exon 26 Silent G4030C Exon 28 Silent A4036G Exon 28 Silent See references [34-39]. Login to comment

[hide] P-glycoprotein: from genomics to mechanism. Oncogene. 2003 Oct 20;22(47):7468-85. Ambudkar SV, Kimchi-Sarfaty C, Sauna ZE, Gottesman MM
P-glycoprotein: from genomics to mechanism.
Oncogene. 2003 Oct 20;22(47):7468-85., 2003-10-20 [PMID:14576852]

Abstract [show]
Resistance to chemically different natural product anti-cancer drugs (multidrug resistance, or MDR) results from decreased drug accumulation, resulting from expression of one or more ATP-dependent efflux pumps. The first of these to be identified was P-glycoprotein (P-gp), the product of the human MDR1 gene, localized to chromosome 7q21. P-gp is a member of the large ATP-binding cassette (ABC) family of proteins. Although its crystallographic 3-D structure is yet to be determined, sequence analysis and comparison to other ABC family members suggest a structure consisting of two transmembrane (TM) domains, each with six TM segments, and two nucleotide-binding domains. In the epithelial cells of the gastrointestinal tract, liver, and kidney, and capillaries of the brain, testes, and ovaries, P-gp acts as a barrier to the uptake of xenobiotics, and promotes their excretion in the bile and urine. Polymorphisms in the MDR1 gene may affect the pharmacokinetics of many commonly used drugs, including anticancer drugs. Substrate recognition of many different drugs occurs within the TM domains in multiple-overlapping binding sites. We have proposed a model for how ATP energizes transfer of substrates from these binding sites on P-gp to the outside of the cell, which accounts for the apparent stoichiometry of two ATPs hydrolysed per molecule of drug transported. Understanding of the biology, genetics, and biochemistry of P-gp promises to improve the treatment of cancer and explain the pharmacokinetics of many commonly used drugs.

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85 Kioka et al. (1989) showed a slight increase in resistance to doxorubicin, but no effect on colchicine or vinblastine Table 2 Common MDR1 exonic polymorphisms Exon number Polymorphic nucleotide variant Change in amino acid References 1 À145 - Ito et al. (2001) 1 À129 - Hoffmeyer et al. (2000); Tanabe et al. (2001) 2 61 N21D Cascorbi et al. (2001); Decleves et al. (2000); Hoffmeyer et al. (2000); Kim et al. (2001) 5 307 F103L Hoffmeyer et al. (2000) 7 548 N183S Kim et al. (2001) 10 1107 G369P Hoffmeyer et al. (2000) 11 1199 S400N Cascorbi et al. (2001); Hoffmeyer et al. (2000); Kim et al. (2001) 12 1236 Wobble Cascorbi et al. (2001); Hoffmeyer et al. (2000); Kim et al. (2001); Kioka et al. (1989) 13 1474 R492C Kim et al. (2001) 21 2650 Wobble Kim et al. (2001) 21 2677 893A, S, or T Cascorbi et al. (2001); Kim et al. (2001); Kioka et al. (1989); Mickley et al. (1998) 24 2956 M986V Tanabe et al. (2001) 24 2995 A999T Mickley et al. (1998) 26 3320 Q1107P Cascorbi et al. (2001) 26 3396 Wobble Hoffmeyer et al. (2000) 26 3421 S1141T Kim et al. (2001) 26a 3435 Wobble Hoffmeyer et al. (2000); Kim et al. (2001); Kioka et al. (1989) 28 4030 - Tanabe et al. (2001) 28 4036 - Kioka et al. (1989); Tanabe et al. (2001) a The only polymorphism that correlates with changes in drug delivery and disposition P-glycoprotein SV Ambudkar et al resistance in the SNP located on exon 21, position 2677, Ser893 (Kioka et al., 1989). Login to comment

[hide] Haplotype analysis of ABCB1/MDR1 blocks in a Japan... Pharmacogenetics. 2003 Dec;13(12):741-57. Sai K, Kaniwa N, Itoda M, Saito Y, Hasegawa R, Komamura K, Ueno K, Kamakura S, Kitakaze M, Shirao K, Minami H, Ohtsu A, Yoshida T, Saijo N, Kitamura Y, Kamatani N, Ozawa S, Sawada J
Haplotype analysis of ABCB1/MDR1 blocks in a Japanese population reveals genotype-dependent renal clearance of irinotecan.
Pharmacogenetics. 2003 Dec;13(12):741-57., [PMID:14646693]

Abstract [show]
We performed comprehensive haplotyping of ABCB1/MDR1 gene blocks using 49 genetic polymorphisms, including seven novel ones, obtained from 145 Japanese subjects. The ABCB1/MDR1 gene was divided into four blocks (Blocks -1, 1, 2, and 3) based on linkage disequilibrium analysis of polymorphisms. Using an expectation-maximization based program, 1, 2, 8, and 3 haplotype groups (3, 12, 32, and 18 haplotypes) were identified in Blocks -1, 1, 2, and 3, respectively. Within Block 2, haplotype groups *1, *2, *4, *6, and *8 reported by Kim and colleagues (Clin Pharmacol Ther 2001; 70:189-199) were found, and additional three groups (*9 to *11) were newly defined. We analyzed the association of haplotypes with the renal clearance of irinotecan and its metabolites in 49 Japanese cancer patients given irinotecan intravenously. There was a significant association of the *2 haplotype in Block 2, which includes 1236C>T, 2677G>T and 3435C>T, with a reduced renal clearance of those compounds. Moreover, tendencies of reduced and increased renal clearance were also observed with *1f in Block 2 and *1b in Block 3, respectively. These findings suggest that the P-glycoprotein encoded by ABCB1/MDR1 in the proximal tubules plays a substantial role in renal exclusion of drugs and, moreover, that block-haplotyping is valuable for pharmacogenetic studies.

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103 746Pharmacogenetics2003,Vol13No12 Copyright(c)LippincottWilliams&Wilkins.Unauthorizedreproductionofthisarticleisprohibited. Table 3 Classification of major ABCB1 haplotypes Site Exon 2 Exon 5 Exon 7 Exon 11 Exon 12 Exon 13 Exon 21 Exon 21 Exon 21 Exon 26 Exon 26 Exon 27 Exon 28 PositionÃ Exon 1 Exon 1 61A.G 325G.A 548A.G 1199G.A 1236C.T 1474C.T 2650C.T 2677G.T 2677G.A 3421T.A 3435C.T 3587T.G 3751G.A Effect on protein À4C.T À1G.A N21D E109K N183S S400N G412G R492C L884L A893S A893T S1141T I1145I I1196S V1251I Classification by Kim et al. [12] Ã1 - - - - - - - - - - - Ã1A - - - - A - - - - - - Ã1B T - - - - - - - - - - Ã1C - - - - - - - - - A - Ã1D - - - G - - - - - - - Ã2 - - - - - T - - T - T Ã2A - - G - - T - - T - T Ã2B - - - - - T - T T - T Ã2C - - - - - T T - T - T Ã3 - - - - - - - - T - T Ã4 - - - - - T - - - - T Ã5 - A - - - - - - - - T Ã6 - - - - - - - - - - T Ã7 - - - - - - - - T - - Ã8 - - - - - T - - - - - Classification of haplotype group detected in this paperÃÃ Block 1 Ã1 - - - - Ã2 - - G - Block 2 Ã1 - - - - - - - - - Ã2 - - T - - T - - T Ã4 - - T - - - - - T Ã6 - - - - - - - - T Ã8 - - T - - - - - - Ã9 - - - - - - - - - Ã10 - - - - - - A - - Ã11 - - T - - - A - - Block 3 Ã1 - - Ã2 - A Ã3 G - ÃAdenine of the initiation codon ATG in exon 2 was numbered +1. Login to comment

[hide] Polymorphisms in human MDR1 (P-glycoprotein): rece... Clin Pharmacol Ther. 2004 Jan;75(1):13-33. Marzolini C, Paus E, Buclin T, Kim RB
Polymorphisms in human MDR1 (P-glycoprotein): recent advances and clinical relevance.
Clin Pharmacol Ther. 2004 Jan;75(1):13-33., [PMID:14749689]

Abstract [show]
Drug transporters are increasingly recognized to be important to drug disposition and response. P-glycoprotein, the encoded product of the human MDR1 (ABCB1) gene, is of particular clinical relevance in that this transporter has broad substrate specificity, including a variety of structurally divergent drugs in clinical use today. Moreover, expression of this efflux transporter in certain tissue compartments such as the gastrointestinal tract and brain capillary endothelial cells limits oral absorption and central nervous system entry of many drugs. Recently, a number of single-nucleotide polymorphisms (SNPs) in MDR1 have been identified. An increasing number of studies have also implicated certain commonly occurring SNPs in MDR1 in problems including altered drug levels and host susceptibility to diseases such as Parkinson's disease, inflammatory bowel disease, refractory seizures, and CD4 cell recovery during human immunodeficiency virus therapy. However, in many such cases, the reported effects of MDR1 SNPs have been inconsistent and, in some cases, conflicting. In this review SNPs in MDR1 in relation to population frequencies, drug levels, and phenotypes are outlined. In addition, issues relating to MDR1 haplotypes, environmental factors, and study design, as potential confounding factors of the observed MDR1 polymorphism effect in vivo, are also discussed.

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75 Summary of genetic polymorphisms in MDR1 Location Position Mutation Effect Mutant allele frequency (%) Hoffmeyer et al89 : C Cascorbi et al90 : C Siegmund et al91 : C Promotor 5' flanking/-41 A/G Noncoding Exon 1a Exon 1a/-145 C/G Noncoding Exon 1b Exon 1b/-129 T/C Noncoding 5.9 Intron 1 Exon 2/-4 C/T Noncoding Intron 1 Exon 2/-1 G/A Initial translation 5.6 9 3.7 Exon 2 Exon 2/61 A/G Asn21Asp 9.3 11.2 8.9 Intron 4 Exon 5/-35 G/C 0.6 Intron 4 Exon 5/-25 G/T 16.5 Exon 5 Exon 5/307 T/C Phe103Leu 0.6 0 Intron 6 Exon 6/ϩ139 C/T 40.6 37.2 35.8 Intron 6 Exon 6/ϩ145 C/T 1.2 Exon 7 Exon 7/548 A/G Asn183Ser Exon 11 Exon 11/1199 G/A Ser400Asn 6.5 5.5 2.9 Exon 12 Exon 12/1236 C/T Silent 37.8 41 34.3 Intron 12 Exon 12/ϩ44 C/T 5.9 4.9 7.5 Exon 13 Exon 13/1474 C/T Arg492Cys Intron 16 Exon 17/-76 T/A 45.3 46.2 49.3 Intron 17 Exon 17/ϩ137 A/G 0.6 Exon 21 Exon 21/2650 C/T Silent Exon 21 Exon 21/2677 G/T Ala893Ser 41.6 40.3 G/A Ala893Thr 1.9 3.7 Exon 24 Exon 24/2956 A/G Met986Val Exon 24 Exon 24/2995 G/A Ala999Thr Exon 26 Exon 26/3320 A/C Gln1107Pro 0.2 Exon 26 Exon 26/3396 C/T Silent 0.3 Exon 26 Exon 26/3421 T/A Ser1141Thr Exon 26 Exon 26/3435 C/T Silent 48.1 53.9 50.7 Exon 28 Exon 28/4030 G/C Exon 28 Exon 28/4036 A/G The positions of the polymorphisms were established with the first base of the ATG start codon set to 1. Login to comment

[hide] Pharmacogenetics of drug transporters and its impa... Curr Top Med Chem. 2004;4(13):1385-98. Sakaeda T, Nakamura T, Okumura K
Pharmacogenetics of drug transporters and its impact on the pharmacotherapy.
Curr Top Med Chem. 2004;4(13):1385-98., [PMID:15379652]

Abstract [show]
Most drug responses are determined by the interplay of several gene products that influence pharmacokinetics and pharmacodynamics, i.e., drug metabolizing enzymes, drug transporters, and drug targets. With the sequencing of the human genome, it has been estimated that approximately 500-1200 genes code for drug transporters. Concerning the effects of genetic polymorphisms on pharmacotherapy, the best characterized drug transporter is the multidrug resistant transporter P-glycoprotein/MDR1, the gene product of MDR1. Little such information is available on other drug transporters. MDR1 is a glycosylated membrane protein of 170 kDa, belonging to the ATP-binding cassette superfamily, and is expressed mainly in intestines, liver, kidneys and brain. A number of various types of structurally unrelated drugs are substrates for MDR1, and their intestinal absorption, hepatobiliary secretion, renal secretion and brain transport are regulated by MDR1. The first investigation on the effects of MDR1 genotypes on pharmacotherapy was reported in 2000: a silent single nucleotide polymorphism (SNP), C3435T in exon 26, was found to be associated with the duodenal expression of MDR1, and thereby the plasma concentration of digoxin after oral administration. At present, a total of 28 SNPs have been found at 27 positions on the MDR1 gene. Clinical investigations on the association of MDR1 genotypes with the expression and function of MDR1 in tissues, and with pharmacokinetics and pharmacodynamics have mainly focused on C3435T; however, there are still discrepancies in the results, suggesting that the haplotype of the gene should be analyzed instead of a SNP. C3435T is also reported to be a risk factor for a certain class of diseases including the inflammatory bowel diseases, Parkinson's disease and renal epithelial tumor, and this also might be explained by the effects on MDR1 expression and function. In this review, the latest reports on the effects of genetic polymorphisms of MDR1 on pharmacotherapy are summarized, and the pharmacogenetics of other transporters is briefly introduced.

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127 Position Location Effect A1a/-41G intron noncoding C-145G exon 1a noncoding T-129C (T12C) exon 1b noncoding C-4T exon 2 noncoding G-1A exon 2 noncoding A61G G5/-25T G5/-35C exon 2 intron intron Asn21Asp T307C C6/+139T exon 5 intron Phe103Leu A548G exon 7 Asn183Ser G1199A exon 11 Ser400Asn C1236T C12/+44T exon 12 intron silent C1474T T17/-76A A17/+137G exon 13 intron intron Arg492Cys C2650T exon 21 silent G2677(A,T) exon 21 Ala893Thr (G2677A) Ala893Ser (G2677T) A2956G exon 24 Met986Val G2995A exon 24 Ala999Thr A3320C exon 26 Gln1107Pro C3396T exon 26 silent T3421A exon 26 Ser1141Thr C3435T exon 26 silent G4030C exon 28 silent A4036G exon 28 silent The list was based on the reports [67,68,71-74]. Login to comment

[hide] Polymorphisms in multidrug resistance 1 (MDR1) gen... Genes Immun. 2004 Nov;5(7):530-9. Potocnik U, Ferkolj I, Glavac D, Dean M
Polymorphisms in multidrug resistance 1 (MDR1) gene are associated with refractory Crohn disease and ulcerative colitis.
Genes Immun. 2004 Nov;5(7):530-9., [PMID:15505619]

Abstract [show]
We used coding and noncoding polymorphisms evenly spaced across the ABCB1/MDR1 gene to perform association analysis in Slovenian patients with inflammatory bowel diseases and to obtain haplotype structure and patterns of linkage disequilibrium (LD) in the MDR1 gene. A disease association study was performed in 307 IBD patients, including 144 patients with ulcerative colitis (UC) and 163 patients with Crohn's disease (CD), and 355 healthy controls. Here we report an association between MDR1 alleles, polymorphisms and haplotypes and refractory CD patients, who do not respond to standard therapy, including patients who develop fistulas. We also report an association with UC and MDR1 polymorphisms in a Slovenian population. Haplotypes significantly associated with diseases were defined by single-nucleotide polymorphisms (SNPs) in exons 12 (1236 C>A), 21(A893S), and 26 (3435 C>T). In addition, two intronic SNPs in LD with the disease haplotype, one in intron 13 (rs2235035) and another in intron 16 (rs1922242), were significantly associated with refractory Crohn (P=0.026, odds ratio (OR) 2.7 and P=0.025, OR 2.8, respectively), as well as with UC (P=0.006, OR 1.8 and P=0.026, OR 1.9, respectively). Our results suggest that MDR1 is a potential target for therapy in refractory CD patients and in patients with UC.

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76 Interestingly, N183S in exon 7, S1140T in exon 26,29 P103L in exon 5, and Q1107P in exon 26 were all identified in apparently healthy individuals. Login to comment

[hide] Single nucleotide polymorphisms in human P-glycopr... Expert Opin Drug Deliv. 2006 Jan;3(1):23-35. Dey S
Single nucleotide polymorphisms in human P-glycoprotein: its impact on drug delivery and disposition.
Expert Opin Drug Deliv. 2006 Jan;3(1):23-35., [PMID:16370938]

Abstract [show]
Drug efflux pumps belong to a large family of ATP-binding cassette transporter proteins. These pumps bind their substrate and export it through the membrane using energy derived from ATP hydrolysis. P-glycoprotein, the main efflux pump in this family, is expressed not only in tumour cells but also in normal tissues with excretory function (liver, kidney and the intestine). It has a broad specificity of substrates and plays an important role in drug delivery and disposition. Recently, genetic screening of P-glycoprotein has yielded multiple single nucleotide polymorphisms, which seem to alter transporter function and expression. This review discusses the various polymorphisms of this gene and its impact on drug disposition and diseases.

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123 Location Position Mutation Effect Promoter 5`/-41 A→G Noncoding Exon 1a Exon 1a/-145 C→G Noncoding Exon 1b Exon 1b/-129 T→C Noncoding Intron 1 Exon 2/-4 C→T Noncoding Intron 1 Exon 2/-1 G→A Initiation of translation Exon 2 Exon 2/61 A→G Asn21Asp Intron 4 Exon 5/-35 G→C Intron 4 Exon 5/-25 G→T Exon 5 Exon 5/307 T→C Phe103Leu Intron 6 Exon 6/+139 C→T Intron 6 Exon 6/+145 C→T Exon 7 Exon 7/548 A→G Asn183Ser Exon 11 Exon 11/1119 G→A Ser400Asn Exon 12 Exon 12/1236 C→T Silent base change Intron 12 Exon 12/+44 C→T Exon 13 Exon 13/1474 C→T Arg492Cys Intron 16 Exon 17/-76 T→A Intron 17 Exon 17/+137 A→G Exon 21 Exon 21/2650 C→T Silent base change Exon 21 Exon 21/2677 G→T G→A Ala893Ser Ala893Thr Exon 24 Exon 24/2956 A→G Met986Val Exon 24 Exon 24/2995 G→A Ala999Thr Exon 26 Exon 26/3320 A→C Gln1107Pro Exon 26 Exon 26/3396 C→T Silent base change Exon 26 Exon 26/3421 T→A Ser1141Thr Exon 26 Exon 26/3435 C→T Silent base change Exon 28 Exon 28/4030 G→C Exon 28 Exon 28/4036 A→G The positions of the polymorphism are from the first base of the ATG start codon set to 1. Login to comment
129 Lastly, rare SNPs located in exon 7 (A548G, Asn183Ser), exon 13 (C1474T, Arg492Cys) and exon 26 (A3320C, Gln1107Pro) leading to amino acid changes have been reported [76,79,96,97]. Login to comment

[hide] MDR1 genotype-related pharmacokinetics: fact or fi... Drug Metab Pharmacokinet. 2005 Dec;20(6):391-414. Sakaeda T
MDR1 genotype-related pharmacokinetics: fact or fiction?
Drug Metab Pharmacokinet. 2005 Dec;20(6):391-414., [PMID:16415525]

Abstract [show]
Multidrug resistant transporter MDR1/P-glycoprotein, the gene product of MDR1, is a glycosylated membrane protein of 170 kDa, belonging to the ATP-binding cassette superfamily of membrane transporters. A number of various types of structurally unrelated drugs are substrates for MDR1, and MDR1 and other transporters are recognized as an important class of proteins for regulating pharmacokinetics. The first investigation of the effects of MDR1 genotypes on pharmacotherapy was reported in 2000; a silent single nucleotide polymorphism (SNP), C3435T in exon 26, was found to be associated with the duodenal expression of MDR1, and thereby the plasma concentration of digoxin after oral administration. In the last 5 years, clinical studies have been conducted around the world on the association of MDR1 genotype with MDR1 expression and function in tissues, and with the pharmacokinetics and pharmacodynamics of drugs; however, there are still discrepancies in the results on C3435T. In 1995, a novel concept to predict in vivo oral pharmacokinetic performance from data on in vivo permeability and in vitro solubility has been proposed, and this Biopharmaceutical Classification System strongly suggested that the effects of intestinal MDR1 on the intestinal absorption of substrates is minimal in the case of commercially available oral drugs, and therefore MDR1 genotypes are little associated with the pharmacokinetics after oral administration. This review summarizes the latest reports for the future individualization of pharmacotherapy based on MDR1 genotyping, and attempts to explain discrepancies.

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29 Representative genetic polymorphisms in MDR1 Position Location EŠect A1aW-41G intron noncoding C-145G exon 1a noncoding T-129C (T12C) exon 1b noncoding C-4T exon 2 noncoding G-1A exon 2 noncoding A61G exon 2 Asn21Asp G5W-25T intron G5W-35C intron T307C exon 5 Phe103Leu C6W＋139T intron C6W＋145T intron A548G exon 7 Asn183Ser G1199A exon 11 Ser400Asn C1236T exon 12 silent C12W＋44T intron C1474T exon 13 Arg492Cys T17W-76A intron A17W＋137G intron C2650T exon 21 silent G2677A,T exon 21 Ala893Thr (G2677A) Ala893Ser (G2677T) A2956G exon 24 Met986Val G2995A exon 24 Ala999Thr A3320C exon 26 Gln1107Pro C3396T exon 26 silent T3421A exon 26 Ser1141Thr C3435T exon 26 silent G4030C exon 28 silent A4036G exon 28 silent See references 27, 32-36. Login to comment

[hide] P-glycoprotein: tissue distribution, substrates, a... Handb Exp Pharmacol. 2011;(201):261-83. Cascorbi I
P-glycoprotein: tissue distribution, substrates, and functional consequences of genetic variations.
Handb Exp Pharmacol. 2011;(201):261-83., [PMID:21103972]

Abstract [show]
P-glycoprotein (ABCB1, MDR1) belongs to the ABC transporter family transporting a wide range of drugs and xenobiotics from intra- to extracellular at many biological interfaces such as the intestine, liver, blood-brain barrier, and kidney. The ABCB1 gene is highly polymorphic. Starting with the observation of lower duodenal protein expression and elevated digoxin bioavailability in relation to the 3435C>T single nucleotide polymorphism, hundreds of pharmacokinetic and outcome studies have been performed, mostly genotyping 1236C>T, 2677G>T/A, and 3435C>T. Though some studies pointed out that intracellular concentrations of anticancer drugs, for example, within lymphocytes, might be affected by ABCB1 variants resulting in differential outcome, current knowledge of the functional significance genetic variants of ABC membrane transporters does not allow selection of a particular SNP to predict an individual's pharmacokinetics.

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13 Absence of the gene, as being the case in double-knockout mice, is conformable N21D S400N A893S/T Q1107P 3435C>T1236T>C N183S R492C S1141T NBD1 NBD2 Intracellular (e.g. lymphocyte) Extracellular M986V Fig. 1 Two-dimensional structure of ABCB1 with locations of amino acid replacements and two frequent synonymous SNPs, NBD ¼ nucleotide binding domain [adapted from Cascorbi and Haenisch (2010)] Inducer intra cellular ABCB1 Transkription Translation ABCB1 (P-gp) luminal Fig. 2 Induction of ABCB1 via the nuclear PXR/RXR receptor leading to accelerated extrusion of P-glycoprotein substrates with life. Login to comment
81 Table 2 Frequency of ABCB1 genetic variants in Caucasians, position on DNA, putative effect, and frequencies [according to Cascorbi (2006) and Cascorbi and Haenisch (2010)] Position Amino acid or effect Frequency of the variant allele Association to expression, kinetics or drug response 50 -flanking À2903 T>C 0.02a 50 -flanking À2410 T>C 0.10a Decreased mRNAa 50 -flanking À2352 G>A 0.28a 50 -flanking À1910 T>C 0.10a 50 -flanking À1717 T>C 0.02a 50 -flanking À1325 A>G 0.02a 50 -flanking À934 A>G 0.10a 50 -flanking À692 T>C 0.10a Decreased mRNAa 50 -flanking À41 A>G 0.09b IVS 1a À145 C>G 0.02b IVS 1b À129 T>C 0.06b IVS 1b 12 T>C 0.06c IVS 2 À1 G>A 0.09d c. 61 A>G N21D 0.11d IVS 5 À35 G>C Intronic 0.006c IVS 5 À25 G>T Intronic 0.16c IVS 6 þ139 C>T Intronic 0.37d c. 548 A>G N183S 0.01e c. 571 G>A G191R 0.07f Reduced chemotherapy resistancef c. 1199 G>A S400N 0.05d c. 1199 C>T S400I 0.02g Elevated activityg c. 1236 C>T Synonymous 0.41d Increased imatinib disposition and therapy responseh IVS 12 þ44 C>T Intronic 0.05d c. 1474 C>T R492C 0.01e IVS 17 À76 T>A Intronic 0.46d IVS 17 þ137 A>G Intronic 0.006c c. 2650 C>T Synonymous 0.03e c. 2677 G>T/A A893S/T 0.42d /0.02d In vitro increased vmax,i increased imatinib response in CMLh c. 2956 A>G M986V 0.005b c. 3320 A>C Q1107P 0.002d c. 3396 C>T Synonymous 0.03c c. 3421 T>A S1141T 0.00c c. 3435 C>T Synonymous 0.54d Decreased mRNA and protein expression,e, k decreased in vitro transport,l no effect on expression and bioavailability of talinolol,m no effect on in vitro transport,n, o decreased digoxin (continued) 4.2.1 Digoxin The heart glycoside digoxin is widely accepted as typical P-glycoprotein substrate. Login to comment

[hide] An update on ABCB1 pharmacogenetics: insights from... Pharmacogenomics J. 2011 Oct;11(5):315-25. doi: 10.1038/tpj.2011.16. Epub 2011 May 31. Wolf SJ, Bachtiar M, Wang J, Sim TS, Chong SS, Lee CG
An update on ABCB1 pharmacogenetics: insights from a 3D model into the location and evolutionary conservation of residues corresponding to SNPs associated with drug pharmacokinetics.
Pharmacogenomics J. 2011 Oct;11(5):315-25. doi: 10.1038/tpj.2011.16. Epub 2011 May 31., [PMID:21625253]

Abstract [show]
The human ABCB1 protein, (P-glycoprotein or MDR1) is a membrane-bound glycoprotein that harnesses the energy of ATP hydrolysis to drive the unidirectional transport of substrates from the cytoplasm to the extracellular space. As a large range of therapeutic agents are known substrates of ABCB1 protein, its role in the onset of multidrug resistance has been the focus of much research. This role has been of particular interest in the field of pharmacogenomics where genetic variation within the ABCB1 gene, particularly in the form of single nucleotide polymorphisms (SNPs), is believed to contribute to inter-individual variation in ABCB1 function and drug response. In this review we provide an update on the influence of coding region SNPs within the ABCB1 gene on drug pharmacokinetics. By utilizing the crystal structure of the mouse ABCB1 homolog (Abcb1a), which is 87% homologous to the human sequence, we accompany this discussion with a graphical representation of residue location for amino acids corresponding to human ABCB1 coding region SNPs. Also, an assessment of residue conservation, which is calculated following multiple sequence alignment of 11 confirmed sequences of ABCB1 homologs, is presented and discussed. Superimposing a 'heat map' of residue homology to the Abcb1a crystal structure has permitted additional insights into both the conservation of individual residues and the conservation of their immediate surroundings. Such graphical representation of residue location and conservation supplements this update of ABCB1 pharmacogenetics to help clarify the often confounding reports on the influence of ABCB1 polymorphisms on drug pharmacokinetics and response.

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48 Four of the 12 associated nsSNPs (E3/61A4G, E5/266C4T, E17/1985T4C and E17/2005C4T) cannot be mapped to the mouse crystal Table 1 Genetic conservation of amino acids corresponding to ABCB1 coding region SNPs 1 - rs28381804 E3/49T>C (F17L) F17 W16 S16 Y17 Y35 F39 - A42 - - G11 - - 2 - rs41304191 E3/55C>T (L19L) L19 M18 M18 I19 G37 P41 - E44 - - L13 - - 3 - rs76199854 E3/57G>A (L19L) L19 M18 M18 I19 G37 P41 - E44 - - L13 - - --51I--64H-34K93N12N02K02K12N)D12N(G>A16/3E4652829sr-4 7.832.8105P12A01K88D61D18T07T55S34G34N44N)S44N(G>A131/5E3812021sr1sn5 6 ns2 rs41315618 E5/178A>C (I60L) I60 I59 I59 A71 I86 A97 G32 G104 K26 N37 L66 27.3 46.6 1.924.6368N75G64N421Y25G711I601I19V97A97A08A)E08A(A>C932/5E5652829sr3sn7 8 - rs35810889 E5/266C>T (M89T) - M89 F89 S85 T96 I112 - - - - - - - - 9 ns4 rs61607171 E7/431T>C (I144T) TM2 I144 I145 I140 V152 N168 I176 A98 A172 L93 V97 L124 36.4 40.9 2.645.45841G121T711V691A221T002S291S671A461V961V861V)I861V(A>G205/7E32622116sr5sn01 11 s1 rs1128500 E8/540C>T (S180S) S180 S181 S176 S188 E204 S212 L136 N208 E129 E133 E160 27.3 42.0 12 ns6 rs60419673 E8/548A>G (N183S) N183 N184 N179 N191 K207 E215 Q139 Q211 K132 A136 S163 27.3 39.9 9.045.54561G831S431F312G141F712G902G391G181G681G581G)V581G(T>G455/8E1058211sr7sn31 14 s2 rs1128502 E8/555A>T (G185G) G185 G186 G181 G193 G209 G217 F141 G213 F134 S138 G165 45.5 40.9 15 s3 rs2235022 E9/729A>G (E243E) E243 E244 E239 E251 E267 E275 I199 Q271 R192 M196 S223 18.2 33.3 16 s4 rs28381867 E9/738G>A (A246A) A246 A247 A242 A254 R270 M278 E202 V274 A195 T199 Y226 9.1 34.5 17 ns8 rs36008564 E9/781A>G (I261V) C-NBD (Internal) I261 I262 I257 V267 I285 I293 V217 I289 I210 H214 I241 36.4 50.3 18 s5 rs80153317 E10/879T>C (I293I) TM5 I293 I294 I289 I301 L317 M325 L249 I321 R242 S246 F273 18.2 36.3 19 ns9 rs2229109 E12/1199G>A (S400N) N-NBD (Internal) S400 S401 S396 N408 T424 Q439 T355 V428 Q348 T350 H386 18.2 60.7 20 s6 rs1128503 E13/1236C>T (G412G) N-NBD (External) G412 G413 G408 G420 G436 K451 D367 N440 D359 N361 D398 27.3 55.9 21 s7 rs35068177 E13/1308A>G (T436T) T436 T437 T432 T44 I460 C475 V391 I464 L383 I385 I422 54.5 64.6 22 s8 rs41311775 E15/1326G>A (R442R) R442 R443 R438 R450 R466 R481 R397 R470 R389 R391 R428 100.0 54.5 23 s9 rs35633772 E15/1617C>T (I539I) I539 I540 I535 I547 I563 I578 I494 I576 L486 I489 I571 90.9 65.8 24 s10 rs60247941 E15/1632C>T (A544A) A544 A545 A540 A552 A568 A583 A499 A581 I491 A494 A576 63.6 65.1 25 s11 rs2235012 E15/1662G>C (L554L) L554 L555 L550 L562 L578 L593 L509 L591 L501 L504 L586 100.0 73.6 26 s12 rs56871767 E15/1674G>A (T558T) T558 T559 T554 T566 T582 T597 T513 T595 T505 T508 T590 100.0 78.7 27 s13 rs59697741 E15/1695C>T (S565S) S565 S566 S561 S573 S589 S604 S520 S602 S512 S515 S597 100.0 75.4 28 ns10 rs28381902 E15/1696G>A (E566K) E566 E567 E562 E574 E590 E605 E521 E603 E513 E516 E598 100.0 76.6 29 ns11 rs28381914 E16/1777C>T (R593C) R593 R594 R589 R601 R617 R632 R548 R630 T540 E543 R627 54.5 67.3 30 ns12 rs56107566 E16/1778G>A (R593H ) R593 R594 R589 R601 R617 R632 R548 R630 T540 E543 R627 54.5 67.3 31 s14 rs28381915 E16/1794C>T (I598I) I598 I599 I594 I606 I622 I637 I553 I635 I545 I548 I632 100.0 65.5 32 ns13 rs2235036 E16/1795G>A (A599T) A599 A600 A595 A607 I623 V638 C554 V636 V546 V549 F633 54.5 63.6 33 ns14 rs57001392 E16/1837G>T (D613Y) N-NBD (External) D613 D614 D609 S621 R637 Q652 E568 N650 R560 N563 D677 45.5 60.5 -0.0637E--807A516E896K496M176E856L366L266L)R266L(C>T5891/71E06975653sr-43 35 - rs35023033 E17/2005C>T (R669C) R669 R670 R665 R678 I702 D705 S662 T715 - - N743 0.0 - 36 - rs59340265 E17/2037C>T (D679D) D679 D680 D675 N688 D712 N715 S632 N725 - - E753 9.1 - 37 ns15 rs41316450 E18/2207T>A (I736K) TM7 I736 I737 V732 I745 M779 I771 V682 I820 I37 L48 V814 72.7 36.7 38 ns16 rs77144566 E19/2281A>C (A761S) TM8 A761 V763 I757 A769 V802 I796 G706 I844 I647 G655 L836 63.6 42.1 39 ns17 rs41305517 E21/2398G>A (D800N) C-NBD (Internal) D800 D801 D796 D808 H841 D835 E745 D883 S108 P112 E875 9.1 45.4 40 ns18 rs2235039 E21/2401G>A (V801M) C-NBD (External) V801 V802 V797 M809 I842 V836 V746 V884 A109 V113 M876 63.6 47.6 2.035.54409L931S531I219S447V468T078I738T528T038I928I)V928I(G>A5842/22E1852302sr91sn14 42 s15 rs28381966 E22/2505A>G (V835V) V835 V836 V831 L843 T876 T870 L780 T918 N141 T145 F911 45.5 33.0 43 ns20 rs28381967 E22/2506A>G (I836V) I836 I837 I832 I844 V877 I871 L781 V919 I142 V146 F911 63.6 28.5 7.448.18429M951M551I239L497I488D098I758I548I058I948I)M948I(G>A7452/22E03150163sr12sn44 45 s16 rs9282563 E22/2650C>T (L884L) L884 L885 L880 K892 V925 M919 R829 E967 R190 K194 I959 27.3 31.2 7.535.54289P302V991V679S838S829C439S109A988S498A398S)T/A398S(A/T>G7762/22E2852302sr22sn64 4.834.631801M203T892V5701F739G7201L5301T0001S889S399S299S)N299S(A>G5792/52E72194865sr32sn74 5.633.729801E903Q503T2801T449V4301Q2401A7001A599A0001A999A)T999A(A>G5992/52E48725527sr42sn84 49 s17 rs2235044 E26/3084G>A (P1028P) P1028 P1029 P1024 P1036 - P1063 P973 V1111 P332 V334 I1117 0.0 33.0 50 ns25 rs28401798 E26/3151C>G (P1051A) P1051 P1052 P1047 K1059 E1093 Q1086 I996 K1135 P355 P357 P1142 18.2 57.6 51 ns26 rs2707944 E26/3188G>C (G1063A) G1063 G1064 G1059 G1071 G1105 G1098 G1008 G1147 G367 G369 K1154 45.5 53.8 52 s18 rs2707943 E26/3189C>G (G1063G) G1063 G1064 G1059 G1071 G1105 G1098 G1008 G1147 G367 G369 K1154 45.5 53.8 53 ns27 rs74755520 E26/3222A>C (C1074W) C-NBD (Internal) C1074 C1075 C1070 C1082 C1116 C1109 S1019 C1158 G378 S380 S1165 63.6 67.8 54 ns28 rs57521326 E26/3262G>A (D1088N) D1088 D1089 D1084 D1096 D1130 D1123 D1033 D1172 D392 D394 D1179 100.0 53.9 55 ns29 rs41309225 E27/3295A>G (K1099E) K1099 K1100 K1095 I1107 S1141 C1134 R1044 V1183 H403 H405 I1237 18.2 38.5 56 ns30 rs55852620 E27/3320A>C (Q1107P) Q1107 Q1108 Q1103 Q1115 E1149 T1142 R1052 N1191 G411 A413 R1245 27.3 43.7 57 ns31 rs35730308 E27/3322T>C (W1108R) W1108 Q1109 W1104 Q1116 H1150 N1143 S1053 D1192 S412 S414 D1246 27.3 43.5 58 s19 rs34748655 E27/3396C>T (A1132A) C-NBD (Internal) A1132 A1133 A1128 A1140 I1174 S1167 M1077 V1216 L436 A438 K1270 27.3 56.8 59 ns32 rs41309228 E27/3410G>T (S1137I ) S1137 S1138 S1133 S1145 P1179 A1172 S1082 S1220 P440 E443 - 18.2 41.8 60 ns33 rs2229107 E27/3421T>A (S1141T) S1141 S1142 S1137 S1149 T1183 T1176 D1086 S1224 D444 R447 T1277 45.5 50.9 61 s20 rs1045642 E27/3435C>T (I1145I) C-NBD (Internal) I1145 I1146 I1141 I1153 V1187 I1180 I1090 M1228 V447 I450 V1281 72.7 57.6 62 ns34 rs59241388 E28/3502A>G (K1168E) K1168 R1169 R1164 R1176 R1210 R1203 C1113 L1251 E470 V473 N1304 27.3 61.9 63 ns35 rs41309231 E29/3669A>T (E1223D) E1223 E1224 E1219 E1231 E1265 E1258 V1168 Q1306 K525 K528 D1359 27.3 60.2 64 s21 rs2235051 E29/3747C>G (G1249G) C-NBD (Internal) G1249 G1250 G1245 G1257 G1291 G1284 G1194 G1332 G551 G554 T1392 63.6 63.0 65 ns36 rs45456698 E29/3751G>A (V1251I) V1251 V1252 V1247 V1259 I1293 V1286 V1196 I1334 I553 I556 V1394 81.8 59.2 4.957.279931T165T855T9331T1021N1921D8921T4621T2521T7521T6521T)K6521T(A>C7673/92E93412753sr73sn66 C-NBD (External) C-NBD (External) C-NBD (External) C-NBD (External) TM4 - TM9 TM10 - TM1 S. aureus TM12 N-NBD (Internal) N-NBD (External) N-NBD (Internal) C-NBD (External) TM3 C. elegans D. melanoga ster A. thaliana S. pombe # SNP (amino acid substitution) Mapped to Abcb1a domain (internal/external surface) rsNo Conservation (%)a H. Sapiens C. l. Familiaris M. Musculus G. gallus P. falciparum Amino acid residue housing SNP Individual Regional 3 structure E. coli a The conservation of residues corresponding to all coding regions SNPs was obtained following multiple sequence alignment of 11 confirmed ABCB1 homolog protein sequences. Login to comment
100 With the substitution of glycine for a more bulky valine residue, such interactions are removed, allowing for improved dissociation and efflux rates.40,41 Interestingly, as shown in Figure 4a, in the crystal structure, this SNP resides in close 3D proximity with a molecular distance of 10.9 and 5.2 A˚ to two other nonsynonymous SNPs, namely E7/431T4C (I144T) (#ns4 in Figure 2b) and E8/548A4G (N183S) (#ns6 in Figure 2b), respectively. Login to comment

[hide] Gene transfer of drug resistance genes. Implicatio... Ann N Y Acad Sci. 1994 May 31;716:126-38; discussion 138-43. Gottesman MM, Germann UA, Aksentijevich I, Sugimoto Y, Cardarelli CO, Pastan I
Gene transfer of drug resistance genes. Implications for cancer therapy.
Ann N Y Acad Sci. 1994 May 31;716:126-38; discussion 138-43., 1994-05-31 [PMID:7912913]

Abstract [show]
Two general approaches to the gene therapy of cancer have been proposed: (1) strategies that use exogenous genes to modify cancer cells so that they are less malignant or more susceptible to host defenses or to killing by exogenous agents; and (2) approaches that modify host cells so that they are more effective in eliminating cancer cells or more resistant to agents that are used to treat cancer. In both cases, the development of vectors that encode in vivo selectable phenotypes, such as drug resistance, would be extremely valuable because of the inherent inefficiency of gene transfer and the potential of such vectors to protect normal tissues against toxic agents. To allow the selection of cells in vivo that have been transduced with vectors for gene therapy, we have utilized the human multidrug resistance (MDR1) gene. The product of this gene is a 170,000-dalton glycoprotein known as P-glycoprotein, which acts as an energy-dependent efflux pump for a great many cytotoxic anticancer drugs, including doxorubicin, daunorubicin, etoposide, teniposide, actinomycin D, and taxol. Vectors encoding an MDR1 cDNA are able to transduce many cell types, including bone marrow cells, with high efficiency to allow selection of drug resistance in vitro and in vivo in mouse models. Thus, it should be possible to protect the bone marrow of patients undergoing intensive chemotherapy by transduction of their bone marrow with MDR1 vectors. Furthermore, the ability to select for the presence of the MDR1 cDNA in vivo means that it can be used to introduce otherwise nonselectable genes into the bone marrow for therapy of cancer and other diseases.

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65 Summaryofthe PhenotypeoftheVarionsMutations Shown in FIGURE 3 with Respect to Several MDR Drugs Mutation Phenotype Reference Gly 185Val Col t, VP-16t, Vbl J, Act-D J Choi etd.,198935 Gly 185 Val, Asn 183 Ser Col t, Vbl -, Act-D - Currier et d.,19924'3 Pro 223 Ala Col J, Vbl +,Act-D .1 Loo and Clarke, 19934' Gly 338 Ala, Ala 339 Pro Col J, Vbl J, Act-D + Devine et al., 199242 Pro 866 Ala Col J, Vbl 4, Act-D J Loo and Clarke, 199341 Ser 941 Phe Col J, Vbl +,Dox J Gros et d.,199143 FIGURE4. Login to comment

[hide] Biochemistry of multidrug resistance mediated by t... Annu Rev Biochem. 1993;62:385-427. Gottesman MM, Pastan I
Biochemistry of multidrug resistance mediated by the multidrug transporter.
Annu Rev Biochem. 1993;62:385-427., [PMID:8102521]

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740 The second mutation is a point mutation of Asn to Ser at position 183 in the first intracytoplasmic loop of P-glycoprotein (252). Login to comment

[hide] Genetic analysis of the multidrug transporter. Annu Rev Genet. 1995;29:607-49. Gottesman MM, Hrycyna CA, Schoenlein PV, Germann UA, Pastan I
Genetic analysis of the multidrug transporter.
Annu Rev Genet. 1995;29:607-49., [PMID:8825488]

Abstract [show]
The analysis of how human cancers evade chemotherapy has revealed a rich variety of cell-based genetic changes resulting in drug resistance. One of the best studied of these genetic alterations is increased expression of an ATP-dependent plasma membrane transport system, known as P-glycoprotein, or the multidrug transporter. This transporter actively effluxes a large number of natural product, hydrophobic, cytotoxic drugs, including many important anticancer agents. This review focuses on the genetic and molecular genetic analysis of the human multidrug transporter, including structure-function analysis, pre- and posttranslational regulation of expression, the role of gene amplification in increased expression, and the properties of transgenic and "knock-out" mice. One important feature of the MDR gene is its potential for the development of new selectable vectors for human gene therapy.

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180 This mutation made in conjunction with an Asn-to-Ser mutation at position 183 results in recovery of resistance to actinomycin D, vinblastine, and doxorubicin and retention of resistance to colchicine (63). Login to comment

[hide] The permeability P-glycoprotein: a focus on enanti... Expert Opin Drug Metab Toxicol. 2010 Aug;6(8):953-65. Choong E, Dobrinas M, Carrupt PA, Eap CB
The permeability P-glycoprotein: a focus on enantioselectivity and brain distribution.
Expert Opin Drug Metab Toxicol. 2010 Aug;6(8):953-65., [PMID:20504109]

Abstract [show]
IMPORTANCE OF THE FIELD: The permeability glycoprotein (P-gp) is an important protein transporter involved in the disposition of many drugs with different chemical structures, but few studies have examined a possible stereoselectivity in its activity. P-gp can have a major impact on the distribution of drugs in selected organs, including the brain. Polymorphisms of the ABCB1 gene, which encodes for P-gp, can influence the kinetics of several drugs. AREAS COVERED IN THIS REVIEW: A search including publications from 1990 up to 2009 was performed on P-gp stereoselectivity and on the impact of ABCB1 polymorphisms on enantiomer brain distribution. WHAT THE READER WILL GAIN: Despite stereoselectivity not being expected because of the large variability of chemical structures of P-gp substrates, structure-activity relationships suggest different P-gp-binding sites for enantiomers. Enantioselectivity in the activity of P-gp has been demonstrated by in vitro studies and in animal models (preferential transport of one enantiomer or different inhibitory potencies towards P-gp activity between enantiomers). There is also in vivo evidence of an enantioselective drug transport at the human blood-brain barrier. TAKE HOME MESSAGE: The significant enantioselective activity of P-gp might be clinically relevant and must be taken into account in future studies.

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209 Different SNPs were associated with the phenotype of remission, and carriers of the C allele for the rs2032583 genotype had higher odds ratio for remission (7.72, 95% CI 2.8 -- 21.3) at 4 weeks Exon 7 Exon 13 Exon 11Exon 2 Exon 8 Exon 6 Exon 3 Exon 4 Exon 9 Exon 17 Exon 10 Exon 14 Exon 12 Exon 15 Exon 16 Exon 19 Exon 21 Exon 18 Exon 23 Exon 24 Exon 28 Exon 27 Exon 20 Exon 22 A893S Exon 25 Exon 26 Exon 5 N21D N183S N400S Variant (548G, Ser183) MDR1*1 (548A, Asn183) Variant (2677T, Ser893) S1141T ATP-binding domain ATP-binding domain MDR1*1 (2677g, Ala893) R492C A. B. Figure 2. Login to comment

[hide] Molecular genetic analysis and biochemical charact... Semin Cell Dev Biol. 2001 Jun;12(3):247-56. Hrycyna CA
Molecular genetic analysis and biochemical characterization of mammalian P-glycoproteins involved in multidrug resistance.
Semin Cell Dev Biol. 2001 Jun;12(3):247-56., [PMID:11428917]

Abstract [show]
A variety of human cancers become resistant or are intrinsically resistant to treatment with conventional drug therapies. This phenomenon is due in large part to the overexpression of a 170 kDa plasma membrane ATP-dependent pump known as the multidrug resistance transporter or P-glycoprotein. P-glycoprotein is a member of the large ATP binding cassette (ABC) superfamily of membrane transporters. This review focuses on the use of structure-function analyses to elucidate further the mechanism of action of mammalian P-glycoproteins. Ultimately, a complete understanding of the mechanism is important for the development of novel strategies for the treatment of many human cancers.

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27 List of mutations in human, mouse and hamster P-gp`s that affect substrate specificity f aaa Mutation Regionb Sourcec Reference aa 78-97 EC 1 human MDR1 78 (ABC20)d Q128He TM 2 mouse mdr3 79 R138H IC 1 mouse mdr3 79 Q139H, R IC 1 mouse mdr3 79 G141V IC 1 human MDR1 25,80 Q145H IC 1 mouse mdr3 79 E155G, K IC 1 mouse mdr3 79 F159I IC 1 mouse mdr3 79 D174G IC 1 mouse mdr3 79 S176F, P IC 1 mouse mdr3 79 K177I IC 1 mouse mdr3 79 N179S IC1 mouse mdr3 79 N183S/G185V IC 1 human MDR1 81 G183D IC1 mouse mdr3 79 G185V IC 1 human MDR1 82-84 G187V IC 1 human MDR1 80 A192T TM 3 mouse mdr3 79 F204S EC 2 mouse mdr3 79 W208G EC 2 mouse mdr3 79 K209E EC 2 mouse mdr3 79 L210I TM 4 mouse mdr3 79 T211P TM 4 mouse mdr3 79 I214T TM 4 mouse mdr3 79 P223A TM 4 human MDR1 85 K285T IC 2 human MDR1 1 G288V IC 2 human MDR1 80 I299M, T319S, L322I, TM 5, EC3, IC 3 human MDR1 86 G324K, S351N V334 TM 6 human MDR1 1 F335A TM 6 human MDR1 25 F335 TM 6 human MDR1 87 V338A TM 6 human MDR1 88 G338A, A339P TM 6 hamster PGY 1 89,90 A339P TM 6 hamster PGY 1 90 G341V TM 6 human MDR1 88 K536R,Q N-NBD human MDR1 91 ERGA→DKGT N-NBD mouse mdr3 92 (aa 522-525) T578C N-NBD mouse mdr3 92 G812V IC 4 human MDR1 80 G830V IC 4 human MDR1 25,80 P866A TM 10 human MDR1 85 F934A TM 11 mouse mdr3 93 G935A TM 11 mouse mdr3 93 I936A TM 11 mouse mdr3 93 F938A TM 11 mouse mdr3 93 S939A TM 11 mouse mdr3 93 S939F TM 11 mouse mdr3 94,95 S941F TM 11 mouse mdr1 94,95 T941A TM 11 mouse mdr3 93 Q942A TM 11 mouse mdr3 93 Table 1-continued aaa Mutation Regionb Sourcec Reference A943G TM 11 mouse mdr3 93 Y946A TM 11 mouse mdr3 93 S948A TM 11 mouse mdr3 93 Y949A TM 11 mouse mdr3 93 C952A TM 11 mouse mdr3 93 F953A TM 11 mouse mdr3 93 F983A TM 12 human MDR1 96 L975A, V981A, F983A TM 12 human MDR1 96 M986A, V988A, TM 12 human MDR1 96 Q990A, V991A V981A, F983A TM 12 human MDR1 96 L975A, F983A TM 12 human MDR1 96 L975A, V981A TM 12 human MDR1 96 F978 TM 12 human MDR1 1 F978A TM 12 human MDR1 25 a aa, amino acid. Login to comment