Mild hyperthermia-induced apoptosis is dependent on p53 in human lymphoid cells

Mild hyperthermia is known to enhance apoptosis. The p53 tumor-suppressor g ene product has been shown to function in apoptosis in response to genotoxi c stress. However, there is little information regarding the mechanism of p 53-dependent apoptosis induced by heat stress. In present study, a p53 cont ribution in mild hyperthermia-induced apoptosis was investigated in human l ymphoid system. After 30-minute exposure at 44 degrees C, the accumulation of p53 protein was clearly observed in TK6 and ML-1 cells. Using comet assa y, the more significant sensitivity to hyperthermic apoptosis was found in TK6 (wild-type p53) than in WI-L2-NS (mutated in p53). Furthermore, the sig nificantly rapid shifting from early apoptotic phase to late apoptotic was observed in heat-induced p53 TK6 cells. These findings suggest that p53-dep endent apoptosis is efficaciously induced by mild hyperthermia as non-genot oxic stress in human lymphoid system.