Received for publication August 3, 2006.
Revised January 14, 2007.
Accepted for publication January 16, 2007.

Identification and Functional Assessment of BCRP Polymorphisms in a Korean Population

Abstract

The breast cancer resistance protein (BCRP) is a member of the ATP-binding cassette transporters. The aim of the present study was to identify genetic variants of BCRP in Koreans and to assess the functional consequences of BCRP polymorphisms. Twenty single nucleotide polymorphisms (SNPs), including four nonsynonymous SNPs, were identified by DNA sequencing of the BCRP gene in 92 Korean subjects. BCRP V12M, Q141K, P269S, and Q126Stop were detected at frequencies of 23%, 28%, 0.2%, and 1.9%, respectively. These four coding variants were also screened in Chinese and Vietnamese subjects, the allelic frequencies among the three populations were compared, and predictions were made as to the potential frequency of each variant. In vitro functional analyses of the P269S protein and the promoter SNP -19031C>T (mutated in the hypoxia inducible factor-1-binding site) were performed and compared with those of the wild-type. P269S exhibited 35-40% decrease in vesicular uptake of [³H]-estrone-3-sulfate (ES) and [³H]-methotrexate (MTX) compared to the wild-type. The promoter SNP -19031C>T did not affect BCRP promoter activity in either the presence or absence of chemical-induced hypoxic stress. Our results suggest that the P269S variant could be a functionally altered variant. Genotyping of this variant in clinical studies is needed to address its phenotypic role. Genetic polymorphisms of BCRP were found to be very common in Koreans, as well as in other ethnic groups. Comparative analyses among three Asian populations revealed different frequencies for the four functional BCRP variants.

Key words: ABC transporters, ethnic differences, genetic polymorphism, genotype, membrane transport, multi-drug resistance, pharmacogenetics, polymorphisms