Olomoucine II, but Not Purvalanol A, Is Transported by Breast Cancer Resistance Protein (ABCG2) and P-Glycoprotein (ABCB1)
Figure 5
Transport of purvalanol A at concentrations of 1 µM (A, B, C) and 10 µM (D, E, F) across monolayers of MDCKII-ABCG2 (A, D), MDCKII-ABCB1 (B, E) and MDCKII-par (C, F) cells.
5 µM fumitremorgin C (FTC) was used as a specific ABCG2 inhibitor in MDCKII-ABCG2 cells. 1 µM LY335979 (LY) was employed as a specific ABCB1 inhibitor in MDCKII-ABCB1 cells. Ratios of purvalanol A transport across cell monolayers (purvalanol A transport in basolateral to apical direction divided by transport in apical to basolateral direction) with or without inhibitor were calculated and statistically compared (see insets). Transport ratios were determined 6 h after purvalanol A addition. In basolateral to apical transport direction, purvalanol A was added into the basolateral compartment and its concentrations were determined in the apical compartment. In the opposite transport direction, purvalanol A was applied into the apical compartment and its concentrations were analyzed in the basolateral compartment. ▴, basolateral to apical transport without inhibitor; ▾, apical to basolateral transport without inhibitor; ▵, basolateral to apical transport with inhibitor; ▿, apical to basolateral transport with inhibitor. Data are expressed as means ± SD of three independent experiments.