TABLE 1.

Sorafenib and vorinostat synergize in colony formation assays to kill colon cancer cells

Colon cancer (HCT116, SW480) cells were treated 12 h after plating as single cells (250-1500 cells/well) in sextuplicate with vehicle (DMSO), sorafenib (3.0-6.0 μM), vorinostat (250-500 nM), or with both drugs combined, as indicated at a fixed concentration ratio, to perform median dose-effect analyses for the determination of synergy. After drug exposure (48 h), the medium was changed, and cells were cultured in drug-free media for an additional 10 to 14 days. Cells were fixed and stained with crystal violet, and colonies of >50 cells/colony counted. Colony formation data were entered into the Calcusyn program, and CI values were determined. A CI value of less than 1.00 indicates synergy; a CI value of greater than 1.00 indicates antagonism.

Cell Line	Sorafenib	Vorinostat	CI
	μM	μM
HCT116	3.0	0.250	0.46
	4.5	0.375	0.59
	6.0	0.500	0.66
SW480	3.0	0.250	0.57
	4.5	0.375	0.59
	6.0	0.500	0.49