Functional analysis of SNPs variants of BCRP/ABCG2.
OBJECTIVE
The aim of the current study was to identify the effect of single nucleotide polymorphisms (SNPs) in breast cancer resistance protein (BCRP/ABCG2) on its localization, expression level, and transport activity.


METHODS
The cellular localization was identified using the wild type and seven different SNP variants of BCRP (V12M, Q141K, A149P, R163K, Q166E, P269S, and S441N BCRP) after transfection of their cDNAs in plasmid vector to LLC-PK1 cells. Their expression levels and transport activities were determined using the membrane vesicles from HEK293 cells infected with the recombinant adenoviruses containing these kinds of BCRP cDNAs.


RESULTS
Wild type and six different SNP variants of BCRP other than S441N BCRP were expressed on the apical membrane, whereas S441N BCRP showed intracellular localization. The expression levels of Q141K and S441N BCRP proteins were significantly lower compared with the wild type and the other five variants. Furthermore, the transport activity of E1S, DHEAS, MTX, and PAH normalized by the expression level of BCRP protein was almost the same for the wild type, V12M, Q141K, A149P, R163K, Q166E, and P269S BCRP.


CONCLUSIONS
These results suggest that Q141K SNPs may associate with a lower expression level, and S441N SNPs may affect both the expression level and cellular localization. It is possible that subjects with these polymorphisms may have lower expression level of BCRP protein and, consequently, a reduced ability to export these substrates.
Kondo
Chihiro
C
School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Suzuki
Hiroshi
H
Itoda
Masaya
M
Ozawa
Shogo
S
Sawada
Jun-ichi
J
Kobayashi
Daisuke
D
Ieiri
Ichiro
I
Mine
Kazunori
K
Ohtsubo
Kenji
K
Sugiyama
Yuichi
Y
D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D001692:Biological Transport; D015153:Blotting, Western; D017931:DNA Primers; D005822:Genetic Vectors; D006801:Humans; D007150:Immunohistochemistry; D018374:LLC-PK1 Cells; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013552:Swine; D022161:Transport Vesicles / Q000378:metabolism
C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D017931:DNA Primers; D009363:Neoplasm Proteins