TABLE 1

IC₅₀ concentrations for 5-azacytidine in cancer cell lines and normal fibroblast Wi38 cells after 72 hours of treatment

Cells were incubated for 72 hours with increasing concentrations of 5-azacytidine. The effect of NBTI or dipyridamole was determined by preincubation of cells for 20 minutes before drug treatment. Cell viability was determined with CellTiter-Blue assay, and the IC₅₀ concentrations were calculated as the nucleoside analog concentration required to reduce cell viability by 50%. Every data point was measured in quadruplicate, and every experiment was reproduced independently at least once.

Cell Line	IC₅₀
Cell Line	5-Azacytidine	5-Azacytidine Preincubated with 10 µM NBTI	5-Azacytidine Preincubated with 1 µM Dipyridamole
	nM
U937	45 ± 8	2101 ± 186^*	306 ± 100**
K562	160 ± 55	243 ± 88***	571 ± 21^*
ML1	276 ± 48	24,862 ± 4420^*	12,603 ± 2846^*
HL60	110 ± 25	640 ± 32^*	1495 ± 299^*
Jurkat	444 ± 48.1	1983 ± 164^*	3849 ± 561^*
KG-1	265 ± 86	524 ± 82**	859 ± 125^*
HCT116	513 ± 41	5376 ± 909^*	11,031 ± 3264^*
PC3	731 ± 169	23,079 ± 5917^*	21,366 ± 8256**
Wi38	2845 ± 762	19,094 ± 4752^*	16,469 ± 3612^*

↵* P < 0.001; **P < 0.01; and ***P = 0.1 compared with IC₅₀ concentrations from the corresponding cell line in the absence of inhibitor.