TABLE 1

Cell sensitivity of A549 and A549/Pt cells to different agents

Cell sensitivity to the different agents was assessed by growth-inhibition assay based on cell counting. Cells were exposed to drug for 72 hours and counted at the end of treatment. IC₅₀ is defined as the drug concentration inhibiting cell growth by 50%.

	IC₅₀		RI^{^a}
	A549	A549/Pt	RI^{^a}
	µM
Cisplatin	0.9 ± 0.1	7.6 ± 1.2	8.4
Topotecan	0.015 ± 0.003	0.029 ± 0.005	2.0
Gemcitabine	0.0045 ± 0.001	0.028 ± 0.003	6.2
Paclitaxel	0.019 ± 0.004	0.04 ± 0.002	2.1
Arsenic trioxide	7.8 ± 3	30.3 ± 6.5	3.9
Sanguinarine	1.45 ± 0.2	2.2 ± 0.15	1.5

↵a RI, resistance index, ratio between IC₅₀ of cisplatin-resistant and -sensitive cells.