title: Influence of single-nucleotide polymorphisms in the multidrug resistance-1 gene on the cellular export of nelfinavir and its clinical implication for highly active antiretroviral therapy.
abstract: Protease inhibitors (PIs) such as nelfinavir (NFV) suppress HIV replication. PIs are substrates of P-glycoprotein (P-gp), the product of the multidrug-resistance-1 (MDR1) gene. Three single-nucleotide polymorphisms (SNPs) are present in exons of the MDR1 gene: MDR1 1236, MDR1 2677 and MDR1 3435. We speculated that these genetic polymorphisms affected PI concentration in the cell. To verify this hypothesis, we first genotyped these SNPs in 79 Japanese patients by the SNaPshot method and found incomplete linkage disequilibrium between the SNPs. Because the SNP at MDR1 3435 has been reported to be associated with P-gp expression, we evaluated the effect of that SNP on the export of NFV from HIV-positive patients' lymphoblastoid cell lines by measuring time-dependent decrease in the amount of intracellular NFV by high-performance liquid chromatography. We found the intracellular concentration of NFV in lymphoblastoid cell lines (LCLs) with the homozygous T/T genotype at MDR1 3435 were higher than that with C/C genotype with statistical significance. This suggests that the activity of P-gp in patients' LCL cells with the MDR1 3435 T/T genotype was lower. In a retrospective study we evaluated the effect of the SNPs on CD4 cell count recovery in response to antiretroviral treatment with PIs, and obtained statistically significant evidence that suggested marginal association of the SNP at MDR1 1236 but not at MDR1 2677 or MDR1 3435. As in vitro results were not consistent with the clinical evaluation, clinical importance of MDR1 genotyping for antiretroviral therapy remains to be investigated in a larger, case-controlled study.
authors.affiliation: Division of Infectious Diseases, Advanced Clinical Research Centre, Institute of Medical Science, University of Tokyo, Tokyo, Japan.
authors.forename: Dayong
authors.initials: D
authors.lastname: Zhu
authors.forename: Hitomi
authors.initials: H
authors.lastname: Taguchi-Nakamura
authors.forename: Mieko
authors.initials: M
authors.lastname: Goto
authors.forename: Takashi
authors.initials: T
authors.lastname: Odawara
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Nakamura
authors.forename: Harumi
authors.initials: H
authors.lastname: Yamada
authors.forename: Hajime
authors.initials: H
authors.lastname: Kotaki
authors.forename: Wataru
authors.initials: W
authors.lastname: Sugiura
authors.forename: Aikichi
authors.initials: A
authors.lastname: Iwamoto
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kitamura
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics* / Q000378:metabolism; D023241:Antiretroviral Therapy, Highly Active; D018791:CD4 Lymphocyte Count; D002472:Cell Transformation, Viral; D019450:Genes, MDR; D015658:HIV Infections / Q000188:drug therapy / Q000821:virology; D017320:HIV Protease Inhibitors / Q000008:administration & dosage / Q000378:metabolism* / Q000627:therapeutic use; D015497:HIV-1; D004854:Herpesvirus 4, Human; D006801:Humans; D007564:Japan; D008214:Lymphocytes / Q000378:metabolism*; D019888:Nelfinavir / Q000008:administration & dosage / Q000378:metabolism* / Q000627:therapeutic use; D020641:Polymorphism, Single Nucleotide
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D017320:HIV Protease Inhibitors; D019888:Nelfinavir