title: Functions of the breast cancer resistance protein (BCRP/ABCG2) in chemotherapy.
abstract: The breast cancer resistance protein, BCRP/ABCG2, is a half-molecule ATP-binding cassette transporter that facilitates the efflux of various anticancer agents from the cell, including 7-ethyl-10-hydroxycamptothecin, topotecan and mitoxantrone. The expression of BCRP can thus confer a multidrug resistance phenotype in cancer cells, and its transporter activity is involved in the in vivo efficacy of chemotherapeutic agents. Thus, the elucidation of the substrate preferences and structural relationships of BCRP is essential to understanding its in vivo functions during chemotherapeutic treatments. Single nucleotide polymorphisms (SNPs) have also been found to be key factors in determining the efficacy of chemotherapeutics, and those therapeutics that inhibit BCRP activity, such as the SNP that results in a C421A mutant, may result in unexpected side effects of the BCRP- anticancer drugs interaction even at normal dosages. In order to modulate the BCRP activity during chemotherapy, various compounds have been tested as inhibitors of this protein. Estrogenic compounds including estrone, several tamoxifen derivatives in addition to phytoestrogens and flavonoids have been shown to reverse BCRP-mediated drug resistance. Intriguingly, recently developed molecular targeted cancer drugs, such as the tyrosine kinase inhibitors imatinib mesylate, gefitinib and others, can also interact with BCRP. Since both functional SNPs and inhibitory agents of BCRP modulate the in vivo pharmacokinetics and pharmacodynamics of its substrate drugs, BCRP activity is an important consideration in the development of molecular targeted chemotherapeutics.
authors.affiliation: Division of Chemotherapy, Faculty of Pharmacy, Keio University, Tokyo, Japan.
authors.forename: Kohji
authors.initials: K
authors.lastname: Noguchi
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Katayama
authors.forename: Junko
authors.initials: J
authors.lastname: Mitsuhashi
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Sugimoto
mesh_terms: D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D000970:Antineoplastic Agents / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000627:therapeutic use; D001692:Biological Transport; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D004347:Drug Interactions; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D006801:Humans; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020641:Polymorphism, Single Nucleotide; D047428:Protein Kinase Inhibitors / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000627:therapeutic use; D013379:Substrate Specificity
chemical_list: C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D000970:Antineoplastic Agents; D009363:Neoplasm Proteins; D047428:Protein Kinase Inhibitors