TY - JOUR

T1 - Molecular cloning of cDNAs which are highly overexpressed in mitoxantrone-resistant cells

T2 - demonstration of homology to ABC transport genes

AU - Miyake, K

AU - Mickley, L

AU - Litman, Thomas

AU - Zhan, Z

AU - Robey, R

AU - Cristensen, B

AU - Brangi, M

AU - Greenberger, L

AU - Dean, M

AU - Fojo, T

AU - Bates, S E

N1 - Our discovery of MXR / ABCG2 / BCRP

PY - 1999/1/1

Y1 - 1999/1/1

N2 - Reports of multiple distinct mitoxantrone-resistant sublines without overexpression of P-glycoprotein or the multidrug-resistance associated protein have raised the possibility of the existence of another major transporter conferring drug resistance. In the present study, a cDNA library from mitoxantrone-resistant S1-M1-80 human colon carcinoma cells was screened by differential hybridization. Two cDNAs of different lengths were isolated and designated MXR1 and MXR2. Sequencing revealed a high degree of homology for the cDNAs with Expressed Sequence Tag sequences previously identified as belonging to an ATP binding cassette transporter. Homology to the Drosophila white gene and its homologues was found for the predicted amino acid sequence. Using either cDNA as a probe in a Northern analysis demonstrated high levels of expression in the S1-M1-80 cells and in the human breast cancer subline, MCF-7 AdVp3000. Levels were lower in earlier steps of selection, and in partial revertants. The gene is amplified 10-12-fold in the MCF-7 AdVp3000 cells, but not in the S1-M1-80 cells These studies are consistent with the identification of a new ATP binding cassette transporter, which is overexpressed in mitoxantrone-resistant cells.

AB - Reports of multiple distinct mitoxantrone-resistant sublines without overexpression of P-glycoprotein or the multidrug-resistance associated protein have raised the possibility of the existence of another major transporter conferring drug resistance. In the present study, a cDNA library from mitoxantrone-resistant S1-M1-80 human colon carcinoma cells was screened by differential hybridization. Two cDNAs of different lengths were isolated and designated MXR1 and MXR2. Sequencing revealed a high degree of homology for the cDNAs with Expressed Sequence Tag sequences previously identified as belonging to an ATP binding cassette transporter. Homology to the Drosophila white gene and its homologues was found for the predicted amino acid sequence. Using either cDNA as a probe in a Northern analysis demonstrated high levels of expression in the S1-M1-80 cells and in the human breast cancer subline, MCF-7 AdVp3000. Levels were lower in earlier steps of selection, and in partial revertants. The gene is amplified 10-12-fold in the MCF-7 AdVp3000 cells, but not in the S1-M1-80 cells These studies are consistent with the identification of a new ATP binding cassette transporter, which is overexpressed in mitoxantrone-resistant cells.

KW - ATP-Binding Cassette Transporters

KW - Antineoplastic Agents

KW - Base Sequence

KW - Cloning, Molecular

KW - DNA, Complementary

KW - Drug Resistance, Neoplasm

KW - Gene Expression Regulation, Neoplastic

KW - Humans

KW - Mitoxantrone

KW - Molecular Sequence Data

KW - Sequence Analysis, DNA

KW - Tumor Cells, Cultured

KW - ABCG2

KW - ABCG2/BCRP

KW - MXR

M3 - Journal article

C2 - 9892175

VL - 59

SP - 8

EP - 13

JO - Cancer Research

JF - Cancer Research

SN - 0008-5472

IS - 1

ER -