Reduced tumorigenicity and pathogenicity of cervical carcinoma SiHa cells selected for resistance to cidofovir

Table 1 Growth inhibition of SiHa _parental and SiHa _CDV after incubation with CDV, PMEG, cPr-PMEDAP or Ara-C

Compound	Cell line	CC₅₀(μM)			Fold-resistance at day 7
		Day 3	Day 5	Day 7
CDV	SiHa_parental	77.1 ± 22.5.1	15.2 ± 13.6	6.3 ± 6.0	>100
CDV	SiHa_CDV	>634.7	>634.7	>634.7	>100
PMEG	SiHa_parental	0.85 ± 1.14	0.16 ± 0.16	0.10 ± 0.07	2.3
PMEG	SiHa_CDV	1.79 ± 2.34	0.39 ± 0.33	0.23 ± 0.016	2.3
cPr-PMEDAP	SiHa_parental	1.22 ± 0.67	0.21 ± 0.15	0.21 ± 0.06	2.9
cPr-PMEDAP	SiHa_CDV	3.44 ± 0.52	1.22 ± 0.34	0.61 ± 0.09	2.9
Ara-C	SiHa_parental	0.08 ± 0.04	0.06 ± 0.02	0.13 ± 0.02	8.8
	SiHa_CDV	1.15 ± 0.37	0.99 ± 0.37	1.15 ± 0.49

Cells were seeded at a density of 2.5 x 10³ cells per well in a volume of 0.1 ml into 96-well microtiter plates and allowed to proliferate for 24 h. At this time, media containing different drug concentrations (tested in duplicate) were added (100 μl/well). After 3, 5, and 7 days of incubation, the cells were trypsinized and the number of cells was determined with a Coulter Counter. Antiproliferative effects were expressed as CC₅₀ (50% cytostatic concentration), or concentration required to reduce cell growth by 50% (relative to the number of cells in the untreated control cell cultures). Data are mean ± standard deviation of at least two independent experiments. Fold-resistance was calculated as the ratio CC₅₀ for SiHa_CDV to CC₅₀ for SiHa_parental.

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