TABLE 1.

The reversal effects of RN486 on ABCB1-mediated MDR in drug-selected resistant cells.

Treatment	IC50 ± SDa (RFb)
	KB-3-1 (μM)	KB-C2 (μM)
Doxorubicin	0.019 ± 0.004 (1.00)	1.898 ± 0.256 (101.39)
+RN486 (0.3 μM)	0.020 ± 0.008 (1.09)	0.434 ± 0.159 (23.19)*
+RN486 (1 μM)	0.019 ± 0.004 (1.00)	0.029 ± 0.009 (1.54)*
+RN486 (3 μM)	0.013 ± 0.003 (0.78)	0.012 ± 0.002 (0.63)*
+Verapamil (3 μM)	0.013 ± 0.002 (0.71)	0.036 ± 0.008 (1.93)*
Paclitaxel	0.003 ± 0.001 (1.00)	1.820 ± 0.198 (707.30)
+RN486 (0.3 μM)	0.003 ± 0.001 (1.12)	1.427 ± 0.321 (554.31)
+RN486 (1 μM)	0.003 ± 0.001 (1.11)	0.059 ± 0.015 (22.76)*
+RN486 (3 μM)	0.003 ± 0.001 (1.23)	0.003 ± 0.001 (1.30)*
+Verapamil (3 μM)	0.002 ± 0.001 (0.82)	0.062 ± 0.019 (23.96)*
Cisplatin	2.572 ± 0.684 (1.00)	4.108 ± 2.134 (1.60)
+RN486 (0.3 μM)	2.731 ± 0.637 (1.06)	4.460 ± 1.188 (1.73)
+RN486 (1 μM)	3.094 ± 1.140 (1.20)	3.718 ± 1.687 (1.45)
+RN486 (3 μM)	2.871 ± 0.817 (1.12)	4.476 ± 1.799 (1.74)
+Verapamil (3 μM)	2.865 ± 1.278 (1.11)	3.777 ± 0.765 (1.47)

^aIC₅₀ values represent mean ± standard deviation (SD) acquired from at least three independent experiments. ^bResistance fold (RF) was calculated from dividing the IC₅₀ values of parental or resistant cells in the presence or absence of RN486 or positive control inhibitor verapamil by the IC₅₀ values of parental cells without reversal reagent. ^∗p < 0.05 versus control treatment in the absence of reversal reagent.