Treatment with proteasome inhibitor bortezomib decreases organic anion transporting polypeptide (OATP) 1B3-mediated transport in a substrate-dependent manner
HEK293-OATP1B3 cells were seeded in 24-well plates at a density of 1.2 x 105 cells/well and were cultured for 48 h prior to treatment. Human SCH were cultured as described in the Materials and Methods section. Cells were pretreated with chloroquine (CQ) (25 μM, 5 h) or vehicle control (CTL) prior to immunoblotting for OATP1B3 in HEK293-OATP1B3 cells (A) and in day 1 human SCH (B). β-actin served as the loading control in both A and B. OATP1B3 protein levels determined by densitometry were normalized to levels of β-actin. Fold changes of total protein levels of OATP1B3 in chloroquine (CQ) -treated cells vs. vehicle control treatment (CTL) were expressed as mean ± SD (n = 3).