title: The mouse Bcrp1/Mxr/Abcp gene: amplification and overexpression in cell lines selected for resistance to topotecan, mitoxantrone, or doxorubicin.
abstract: Mouse fibroblast cell lines lacking functional Mdr1a, Mdr1b, and Mrp1 genes were selected for resistance to topotecan, mitoxantrone, or doxorubicin. Each of the resulting drug-resistant lines showed marked gene amplification of Bcrp1, the mouse homologue of the human ATP-binding cassette transporter gene BCRP/MXR/ABCP, and greatly elevated expression of Bcrp1 mRNA. All three of the resistant cell lines were highly cross-resistant to topotecan and mitoxantrone and, to a variable extent, doxorubicin. All showed greatly reduced cellular accumulation and greatly increased efflux of mitoxantrone that was dependent on cellular ATP and efficiently reversed by the compound GF120918. The mouse Bcrp1 cDNA encodes a 657-amino-acid protein with 81% identity (86% similarity) to the human breast cancer resistance protein (BCRP) and a virtually superimposable hydrophobicity profile. Our data argue strongly that mouse Bcrp1 is functionally comparable with human BCRP, conferring multidrug resistance to topotecan, mitoxantrone, doxorubicin, and related compounds. Mouse models and cell lines should, therefore, be highly informative in understanding the clinical, pharmacological, and physiological roles of BCRP.
authors.affiliation: Division of Experimental Therapy, The Netherlands Cancer Institute, Amsterdam.
authors.forename: J D
authors.initials: JD
authors.lastname: Allen
authors.forename: R F
authors.initials: RF
authors.lastname: Brinkhuis
authors.forename: J
authors.initials: J
authors.lastname: Wijnholds
authors.forename: A H
authors.initials: AH
authors.lastname: Schinkel
mesh_terms: D016475:3T3 Cells; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics; D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D018076:DNA, Complementary / Q000737:chemistry; D004317:Doxorubicin / Q000493:pharmacokinetics / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005784:Gene Amplification; D051379:Mice; D008942:Mitoxantrone / Q000493:pharmacokinetics / Q000494:pharmacology*; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000032:analysis; D019772:Topotecan / Q000493:pharmacokinetics / Q000494:pharmacology*
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018528:ATP-Binding Cassette Transporters; D018076:DNA, Complementary; D012333:RNA, Messenger; D019772:Topotecan; D004317:Doxorubicin; D008942:Mitoxantrone