title: Modulation of the tumor disposition of vinca alkaloids by PSC 833 in vitro and in vivo.
abstract: PSC 833, a nonimmunosuppressive cyclosporin, is able to inhibit the efflux of antitumor drugs mediated by P-glycoprotein (P-gp). The purpose of the present study is to compare the effect of PSC 833 on the tumor disposition of [3H]vincristine ([3H]VCR) and [3H]vinblastine ([3H]VBL) in in vitro and in vivo experiments from a pharmacokinetic point of view. In in vitro experiments, the effect of PSC 833 was investigated on the cellular uptake of [3H]VCR and [3H]VBL by HCT-15 and COLO 205, human colorectal tumor cell lines with extensive and minimal expression of P-gp, respectively. PSC 833 (2 microM) increased the cellular uptake of [3H]VCR and [3H]VBL by HCT-15 cells, but not that by COLO 205 cells, 8- and 6-fold, respectively, without affecting the initial influx rates. In addition, 2 microM PSC 833 reduced the efflux of [3H]VCR from HCT-15 cells to a level comparable with that from COLO 205 cells. Furthermore, the effect of PSC 833 on the tumor disposition of intravenously administered [3H]VCR and [3H]VBL was studied in tumor inoculated mice. Infusion of PSC 833 (10 microg/hr/mouse) increased the HCT-15 tumor disposition of [3H]VBL and [3H]VCR in vivo to a level comparable with that observed in vitro. These findings demonstrate that PSC 833 enhances the tumor disposition of vinca alkaloids by inhibition of P-gp-mediated efflux not only in vitro but also in vivo in a solid tumor model.
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Song
authors.forename: H
authors.initials: H
authors.lastname: Suzuki
authors.forename: T
authors.initials: T
authors.lastname: Terasaki
authors.forename: M
authors.initials: M
authors.lastname: Lemaire
authors.forename: Y
authors.initials: Y
authors.lastname: Sugiyama
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000032:analysis / Q000096:biosynthesis*; D000818:Animals; D000970:Antineoplastic Agents / Q000378:metabolism*; D003524:Cyclosporins / Q000494:pharmacology*; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D014407:Tumor Cells, Cultured; D014747:Vinblastine / Q000378:metabolism*; D014750:Vincristine / Q000378:metabolism*
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000970:Antineoplastic Agents; D003524:Cyclosporins; D014750:Vincristine; D014747:Vinblastine; C070272:valspodar