Pentoxifylline sensitizes human cervical tumor cells to cisplatin-induced apoptosis by suppressing NF-kappa B and decreased cell senescence

Table 2 Cytotoxic effect of PTX and CIS either alone or in combination on HeLa, SiHa and HaCaT cells.

Agent/combination	Concentration	Surviving fraction	CI
HeLa cells
Pentoxifylline (mM)	2	0.95
	4	0.44
	8	0.23
	16	0.00
Cisplatin (μM)	1	0.97
	2	0.87
	4	0.80
	8	0.08
Pentoxifylline + Cisplatin	2 + 1	0.85	0.795
	4 + 2	0.68	0.605
	8 + 4	0.20	0.974
	16 + 8	0.05	1.766
SiHa cells
Pentoxifylline (mM)	2	0.95
	4	0.54
	8	0.23
	16	0.14
Cisplatin (μM)	1	0.94
	2	0.72
	4	0.65
	8	0.10
Pentoxifylline + Cisplatin	2 + 1	0.70	0.753
	4 + 2	0.56	0.380
	8 + 4	0.28	0.970
	16 + 8	0.005	0.840
HaCaT Cells
Pentoxifylline (mM)	2	0.90
	4	0.87
	8	0.83
	16	0.75
Cisplatin (μM)	1	0.90
	2	0.80
	4	0.78
	8	0.40
Pentoxifylline + Cisplatin	2 + 1	0.86	1.013
	4 + 2	0.75	1.010
	8 + 4	0.80	1.090
	16 + 8	0.05	0.760

Clonogenic assays were assayed for the cytotoxic effects of PTX or CIS or PTX + CIS. Subconfluent cultures were exposed to the drugs for 6 hours. Then the cells were washed, trypsinized and plated in 6-well plates. After 15 days of incubation, the colonies were stained and counted manually. In each case results are expressed as the surviving fraction. The drug interaction was analyzed according to Chou and Talalay determining a combination index (CI). CI < or > 1 indicated synergy or antagonism respectively, whereas a CI value of 1 indicates additivity. The results represent the mean of three independent experiments carried out in triplicate.

ISSN: 1471-2407