title: The novel anticancer drug KRN5500 interacts with, but is hardly transported by, human P-glycoprotein.
abstract: The interaction of the novel anticancer drug KRN5500, a spicamycin derivative, with human P-glycoprotein (P-gp) was analyzed from the viewpoint of cellular pharmacokinetics, i.e. by means of [3H]azidopine photoaffinity labeling, cellular accumulation and transcellular transport experiments. In this study, P-gp-overexpressing LLC-GA5-COL150 cells, porcine kidney epithelial LLC-PK1 cells transformed with human MDR1 cDNA, were used, since this cell line constructs monolayers with tight junctions, and would provide sufficient information for analyzing the cellular pharmacokinetics. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay revealed that the growth-inhibitory effect of KRN5500 in LLC-GA5-COL150 cells was comparable to that in LLC-PK1 cells (IC50 = 79.4 and 72.7 nM, respectively), but the inhibition of [3H]azidopine binding by KRN5500 was concentration-dependent in the membrane fraction of LLC-GA5-COL150 cells. The cellular accumulation of [14C]KRN5500 after its basal application in LLC-GA5-COL150 cells was slightly lower than that in LLC-PK1 cells, and was restored by the multidrug resistance (MDR) modulator SDZ PSC 833. The basal-to-apical transport of [14C]KRN5500 in LLC-GA5-COL150 cells was also slightly higher than that in LLC-PK1 cells, and was inhibited by SDZ PSC 833. However, the basal-to-apical transport of [14C]KRN5500 in LLC-GA5-COL150 cells was only a little higher than the apical-to-basal transport. Consequently, these results demonstrated that KRN5500 interacted with, but was hardly transported via, P-gp. These observations suggested that KRN5500 may be useful even for the treatment of tumors exhibiting P-gp-mediated MDR.
authors.affiliation: Department of Hospital Pharmacy, School of Medicine, Kobe University.
authors.forename: K
authors.initials: K
authors.lastname: Takara
authors.forename: Y
authors.initials: Y
authors.lastname: Tanigawara
authors.forename: F
authors.initials: F
authors.lastname: Komada
authors.forename: K
authors.initials: K
authors.lastname: Nishiguchi
authors.forename: T
authors.initials: T
authors.lastname: Sakaeda
authors.forename: K
authors.initials: K
authors.lastname: Okumura
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000502:physiology*; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000493:pharmacokinetics*; D001386:Azides / Q000378:metabolism; D001692:Biological Transport; D002455:Cell Division / Q000187:drug effects; D004095:Dihydropyridines / Q000378:metabolism; D006801:Humans; D019920:Photoaffinity Labels; D011684:Purine Nucleosides / Q000493:pharmacokinetics / Q000494:pharmacology; D013552:Swine
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000903:Antibiotics, Antineoplastic; D001386:Azides; D004095:Dihydropyridines; D019920:Photoaffinity Labels; D011684:Purine Nucleosides; C041130:azidopine; C092296:KRN 5500