Exposure of murine tumor cells of immune origin to THC in vitro leads to a reduction in cell viability and induction of apoptosis.

(A) The effect of THC on tumor-cell viability was determined by culturing EL-4, LSA, and P815 tumor cells for 24 hours in medium containing 5% FCS in the presence of various concentrations of THC (1, 10, and 20 μM) or the vehicle. The viable cell number was determined by trypan blue dye exclusion. The data were expressed as percentage of control viable cell number. (B) The effect of THC on the induction of apoptosis in EL-4, LSA, and P815 tumor cells was determined by culturing the tumor cells for 24 hours in medium containing 5% FCS in the presence of 20 μM THC (filled histogram) or the vehicle (empty histogram). Apoptosis was quantified using the TUNEL method, and the cells were analyzed using a flow cytometer.