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. Author manuscript; available in PMC: 2014 Jun 1.
Published in final edited form as: Anal Biochem. 2013 Mar 5;437(1):77–87. doi: 10.1016/j.ab.2013.02.018

Fig.6.

Fig.6

Heat map of inhibition responses for seven inhibitors against fluorescent substrates in each of the ABC transporter-overexpressing cell lines. Values are represented as IC50 values without error values for the sake of clarity. ABCB1 (CCRF-ADR 5000) demonstrated the highest number of effluxed fluorescent substrates of the three tested transporter pumps. Mometasone and nicardipine inhibition was observed for all of the shown substrates, which included some of the lowest IC50 values. For example, sub-micromolar inhibition of the cyanine DiOC6(3) (D273) was observed with both mometasone (0.3 ± 0.1 μM) and nicardipine (0.8 ± 0.9 μM). Pimozide and verapamil were also shown to be inhibitors of a majority of the substrates, albeit with higher IC50 values. No activity was seen with niclosamide in ABCB1, and only BODIPY FL EDA (D2390) was inhibited by lasalocid (IC50 = 9.0 ± 6.2 μM). Similar inhibitory activity was seen in ABCC1 (SupT1-Vin) as compared with ABCB1 with the BODIPY, cyanine, and single fluorescein substrates. Of the rhodamine/rosamine substrates shown, only CellTracker Orange CMTMR (C2927), rhodamine B, hexyl ester, perchlorate (R6, R648MP), and tetramethylrosamine chloride (T639) were shown to have inhibitable efflux activity. As in ABCB1, mometasone, nicardipine, pimozide, and verapamil were the common inhibitors. Again, no activity was seen with niclosamide in ABCC1, and only D2390 was inhibited by lasalocid (IC50 = 13.5 ± 2.1 μM). Much less activity was seen in ABCG2 (Ig-MXP3), and except for the three-pump cross-substrate JC-1 (T3168), the inhibition profiles seemed to be more selective. T3168 efflux was inhibited by lasalocid, mometasone,nicardipine, and pimozide in a range of IC50 values. Interestingly, T3168 in ABCG2 was the only substrate efflux inhibited by niclosamide (IC50 = 0.8 ± 0.6 μM). The remaining active substrates were all members of the BODIPY fluorophore subset and included the nicardipine-inhibited three-pump cross-substrates BODIPY FL histamine (B22461), BODIPY FL prazosin (B7433), and BODIPY FL forskolin (B7469). Once again, D2390 was inhibited by lasalocid (IC50 = 4.2 ± 2.4 μM).