[Cytotoxic effect of hyperthermia and nitrocaphane on malignant HEp-2 cells]

Cytotoxic effect of hyperthermia combined with Nitrocaphane (NC) on HEp-2 cells was detected by colony formation assay. The results showed: 1. There was significant synergetic effect on survival fraction of HEp-2 cells when the heat was at 43 degrees C and 44 degrees C and NC at 0.5-4.0 micrograms/ml; 2. There was almost no effect on the cell survival when the heat was at 39 degrees C and 41 degrees C for 1 hr without NC; however, the cytotoxicity of NC (1.0 micrograms/ml) was enhanced when temperature was at 39 degrees C and 41 degrees C; 3. The sequence between heat and NC could influence the synergism. When the heat at 43 degrees C, 60 min and NC at 1.0 micrograms/ml were used simultaneously, the cytotoxicity was the strongest (SF = 0.025). When the heat was given 1-4 hr before or after the drug, the cytotoxicity was decreased. These results suggest that, over the range of 39-44 degrees C, the synergetic effects of hyperthermia and NC on malignant HEp-2 cells provide certain cell biologic basis for clinical application of local or systemic hyperthermia combined with NC.