Effect of protracted mild hyperthermia on polymerase activity in a human melanoma cell line

Abstract

Radioresistant human melanoma SkMel-3 was evaluated with its sensitivity to thermal cell killing and polymerase inactivation. Cells were heated from 40 to 45°C and demonstrated no thermal tolerance development for any of the temperatures tested. In addition, at 45°C the heat survival curve showed a large shoulder indicating capacity for accumulation of sublethal heat damage. Also at 45°C heating polymerase β was more sensitive than polymerase α+δ+ε. At 42°C, the polymerase sensitivities were nearly the same but at the lower temperatures (41 and 40°C) polymerase β became progressively more resistant than the polymerase α+δ+ε. Thus, mild hyperthermia effects may be different than high temperature hyperthermia and may be related to polymerase α+δ+ε activity.