EFFECT OF PROTRACTED MILD HYPERTHERMIA ON POLYMERASE-ACTIVITY IN A HUMAN-MELANOMA CELL-LINE

Radioresistant human melanoma SkMel-5 was evaluated with its sensitivi ty to thermal cell killing and polymerase inactivation. Cells were hea ted from 40 to 45 degrees C and demonstrated no thermal tolerance deve lopment for any of the temperatures tested. In addition, at 45 degrees C the heat survival curve showed a large shoulder indicating capacity for accumulation of sublethal heat damage. Also at 45 degrees C heati ng polymerase beta was more sensitive than polymerase alpha+delta+epsi lon. At 42 degrees C, the polymerase sensitivities were nearly the sam e bht at the lower temperatures (41 and 40 degrees C) polymerase beta became progressively more resistant than the polymerase alpha+delta+ep silon. Thus, mild hyperthermia effects may be different than high temp erature hyperthermia and may be related to polymerase alpha+delta+epsi lon activity.