Acquired mutations in the MXR/BCRP/ABCP gene alter substrate specificity in MXR/BCRP/ABCP-overexpressing cells

TY - JOUR

T1 - Acquired mutations in the MXR/BCRP/ABCP gene alter substrate specificity in MXR/BCRP/ABCP-overexpressing cells

AU - Honjo, Y

AU - Hrycyna, C A

AU - Yan, Q W

AU - Medina-Pérez, W Y

AU - Robey, R W

AU - van de Laar, A

AU - Litman, Thomas

AU - Dean, M

AU - Bates, S E

PY - 2001/9/15

Y1 - 2001/9/15

N2 - A disparity was noted in the transport of rhodamine 123 among nine MXR/BCRP/ABCP-overexpressing cells studied; all demonstrated mitoxantrone transport, whereas only two effluxed rhodamine 123. When the MXR/BCRP/ABCP gene was sequenced in the cell lines studied, differences were noted at amino acid 482, predicted to be at the start of the third transmembrane domain. Sequencing genomic DNA revealed wild-type MXR/BCRP/ABCP to have an arginine at position 482. Cells having a threonine or glycine at position 482 were able to efflux rhodamine 123, whereas cells having an arginine were not. A vaccinia virus expression system confirmed that rhodamine as well as doxorubicin efflux is observed with R482T or R482G but not with the wild-type R482; all three MXR/BCRP/ABCP forms transported mitoxantrone. Cross-resistance studies suggest that, compared with wild-type MXR/BCRP/ABCP, cells having an R482T mutation have higher anthracycline resistance, whereas an R482G mutation seems to confer relatively less resistance to SN-38 and topotecan. These results suggest that amino acid 482 has a crucial role in MXR/BCRP/ABCP function and that mutation of a single amino acid residue significantly changes substrate specificity, thus altering the drug resistance phenotype.

AB - A disparity was noted in the transport of rhodamine 123 among nine MXR/BCRP/ABCP-overexpressing cells studied; all demonstrated mitoxantrone transport, whereas only two effluxed rhodamine 123. When the MXR/BCRP/ABCP gene was sequenced in the cell lines studied, differences were noted at amino acid 482, predicted to be at the start of the third transmembrane domain. Sequencing genomic DNA revealed wild-type MXR/BCRP/ABCP to have an arginine at position 482. Cells having a threonine or glycine at position 482 were able to efflux rhodamine 123, whereas cells having an arginine were not. A vaccinia virus expression system confirmed that rhodamine as well as doxorubicin efflux is observed with R482T or R482G but not with the wild-type R482; all three MXR/BCRP/ABCP forms transported mitoxantrone. Cross-resistance studies suggest that, compared with wild-type MXR/BCRP/ABCP, cells having an R482T mutation have higher anthracycline resistance, whereas an R482G mutation seems to confer relatively less resistance to SN-38 and topotecan. These results suggest that amino acid 482 has a crucial role in MXR/BCRP/ABCP function and that mutation of a single amino acid residue significantly changes substrate specificity, thus altering the drug resistance phenotype.

KW - ATP-Binding Cassette Transporters

KW - Breast Neoplasms

KW - Camptothecin

KW - Doxorubicin

KW - Drug Resistance, Multiple

KW - Drug Resistance, Neoplasm

KW - Genes, MDR

KW - Genetic Vectors

KW - HeLa Cells

KW - Humans

KW - Mitoxantrone

KW - Mutation

KW - Neoplasm Proteins

KW - RNA, Messenger

KW - Rhodamine 123

KW - Substrate Specificity

KW - Topotecan

KW - Transfection

KW - Tumor Cells, Cultured

KW - Vaccinia virus

M3 - Journal article

C2 - 11559526

SN - 0008-5472

VL - 61

SP - 6635

EP - 6639

JO - Cancer Research

JF - Cancer Research

IS - 18

ER -