Synergism between mild hyperthermia and interferon-β gene expression

In the present study, the synergistic effect of mild hyperthermia in combination with gene expression of interferon-β (IFN-β) was examined in vitro in the human glioma cell line U87MG. The cells transiently expressed the IFN-β gene under the control of the mouse mammary tumor virus promoter and were then subjected to temperature elevation (41°C for 1 h). In terms of the cell killing effect, the optimum scheme was obtained by transfection for 4 days before hyperthermia, i.e. rate in the time course of IFN-β gene expression. The relative specific growth rate decreased to 32% compared with the control while it was only 40% under the hyperthermic conditions. These observations suggest that IFNβ expression was able to enhance the sensitivity of transfected glioma cells to mild hyperthermia.