[Preheating decrease the sensitivity of K562 cell to chemotherapeutic drugs]

Hyperthermia is a powerful tool for enhancing the effect of many chemical drugs on killing cells, but too many times of hyperthermia could decrease the effect and increase the ability of tumor cell against chemical drugs. Heat stress protein 70(HSP70) mRNA of K562 cell was analyzed by RT-PCR, and the chemosensitivity of K562 cell was tested by MTT method before and after heat-exposure. The results showed that HSP70 mRNA increased greatly after K562 cells exposed to 40 degrees C for 30 min and then it went to the top after 120 min heat-exposure. The sensitivity of K562 cell to adriamycin (ADM) and cyclophosphamide (CTX) in a usual dosage (1/250 of one dosage in clinical use) was in middle degree before exposed to heat, and the sensitivity dramatically went down after K562 cell being heat-stressed. The sensitivity of heat-stressed tumor cells to chemotherapeutic drugs was decreased, which may come from the increased expression of stress proteins in cells.