title: MDR1 (ABCB1) gene polymorphism C3435T is associated with P-glycoprotein activity in B-cell chronic lymphocytic leukemia.
abstract: Functional single nucleotide polymorphism (SNP) C3435T in exon 26 of the MDR1 ( ABCB1 ) gene encoding the xenobiotic transporter P-glycoprotein (P-gp, MDR1, ABCB1) may influence susceptibility to several diseases as well as clinical outcome of treatment with P-gp substrates. Exposure to environmental chemicals is thought to be involved in the pathogenesis of B-cell chronic lymphocytic leukemia (B-CLL) and P-gp-transported drugs are used in its treatment; however, little is known about the impact of the C3435T MDR1 SNP in B-CLL. In this study, 110 Caucasian B-CLL patients and 201 healthy controls were genotyped for the MDR1 C3435T SNP. Additionally, P-gp activity was assessed in malignant lymphocytes of 22 untreated B-CLL patients. We observed a higher frequency of carriers of at least one 3435T allele (3435CT and 3435TT genotypes) among B-CLL patients as compared to normal individuals (76% vs . 63%, p=0.027). The genotypes 3435CT and 3435TT were associated with B-CLL, (odds ratio=1.8, 95% confidence interval = 1.1-3.0). Moreover, P-gp activity in B-CLL cells depended on MDR1 genotype, with the highest P-gp activity in 3435CC homozygotes, intermediate in 3435CT heterozygotes and the lowest in 3435TT homozygotes (p=0.042). P-gp activity was also significantly lower in carriers of the T-allele (3435CT/TT genotype) as compared to the non-carriers (3435CC genotype), (p=0.029). Taken together, these data indicate that the MDR1 C3435T SNP may carry an increased risk of developing B-CLL, possibly by virtue of decreased protection against P-gp-substrate carcinogens. The differences in P-gp activity in B-CLL tumor cells related to MDR1 genotype may have implications to the response to chemotherapy with P-gp transported anticancer agents.
authors.affiliation: Department of Hematology, Medical University of Łódź,, Ciołkowskiego 2, PL 93-510 Łódź, Poland.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Jamroziak
authors.forename: Ewa
authors.initials: E
authors.lastname: Balcerczak
authors.forename: Piotr
authors.initials: P
authors.lastname: Smolewski
authors.forename: Robert W
authors.initials: RW
authors.lastname: Robey
authors.forename: Barbara
authors.initials: B
authors.lastname: Cebula
authors.forename: Mariusz
authors.initials: M
authors.lastname: Panczyk
authors.forename: Monika
authors.initials: M
authors.lastname: Kowalczyk
authors.forename: Anna
authors.initials: A
authors.lastname: Szmigielska-Kapłon
authors.forename: Marek
authors.initials: M
authors.lastname: Mirowski
authors.forename: Susan E
authors.initials: SE
authors.lastname: Bates
authors.forename: Tadeusz
authors.initials: T
authors.lastname: Robak
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics* / Q000378:metabolism*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018432:Drug Resistance, Multiple / Q000235:genetics; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1