title: Arginine 482 to glycine mutation in ABCG2/BCRP increases etoposide transport             and resistance to the drug in HEK-293 cells.
abstract: Resistance to etoposide has been associated with the overexpression of P-glycoprotein             and MRP1 in human tumor cells. However, the role of BCRP in resistance to etoposide             has not been clearly established, especially the significance of arginine 482             mutations in drug transport (cellular uptake and efflux). Different levels of             resistance to etoposide have been recently observed in cells expressing BCRP in             terms of cytotoxicity. The aim of this work was to study the effects of these             mutations on the functional involvement of BCRP in etoposide transport. HEK293             cells were transfected with an empty vector (HEK/V), the vector bearing the wild-type             BCRP (HEK/R482), the mutant arginine-482-glycine (HEK/R482G) or the mutant arginine-482-threonine             (HEK/R482T). MTT assay was used to study the cytotoxic effect of etoposide and             [3H]-etoposide was used to determine cellular drug uptake and efflux. Data show             that HEK/R482G cells displayed the highest levels of resistance to etoposide.             Cellular [3H]-etoposide uptake was lower in HEK/R482, HEK/R482G and HEK/R482T             cells compared to HEK/V cells. In addition, cellular [3H]-etoposide uptake in             HEK/R482G was the lowest. Drug efflux measurements showed that fumitremorgin C             was able to increase the residual cellular [3H]-etoposide uptake in BCRP-transfected             cells and especially in HEK/R482G ones. Our data show that the R482G mutation             in BCRP is able to increase efflux of etoposide and that mutation analysis at             codon 482 may be of clinical importance in cancers treated with etoposide.
authors.affiliation: MEDyC Unité CNRS UMR6237, UFR de Pharmacie, IFR53, 51096 Reims,                     France.
authors.forename: Lahcen
authors.initials: L
authors.lastname: Eddabra
authors.forename: Thomas
authors.initials: T
authors.lastname: Wenner
authors.forename: Hassan
authors.initials: H
authors.lastname: El Btaouri
authors.forename: Thomas
authors.initials: T
authors.lastname: Baranek
authors.forename: Claudie
authors.initials: C
authors.lastname: Madoulet
authors.forename: Pascale
authors.initials: P
authors.lastname: Cornillet-Lefebvre
authors.forename: Hamid
authors.initials: H
authors.lastname: Morjani
mesh_terms: D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D000972:Antineoplastic Agents, Phytogenic / Q000378:metabolism*; D001120:Arginine / Q000235:genetics; D001692:Biological Transport / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005047:Etoposide / Q000378:metabolism*; D005434:Flow Cytometry; D005998:Glycine / Q000235:genetics; D057809:HEK293 Cells; D006801:Humans; D009363:Neoplasm Proteins / Q000235:genetics*; D017354:Point Mutation; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection
chemical_list: C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D000972:Antineoplastic Agents, Phytogenic; D009363:Neoplasm Proteins; D005047:Etoposide; D001120:Arginine; D005998:Glycine