Induction of heat shock protein 70 in drug-resistant cells by anticancer drugs and hyperthermia.

The altered constitutive and inducible levels of heat shock proteins 70 (Hsp70) in drug-resistant cells may influence the efficiency of combined hyperthermia and anticancer drug treatment. In the present study, the constitutive levels of Hsp70 and induction of these proteins by hyperthermia and two anticancer drugs (used for resistance development) were determined in cervical and laryngeal carcinoma cells. The levels of Hsp70 were quantified by Western blot. Constitutive levels of Hsp70 were similar in parental and drug-resistant cells suggesting that Hsp70 is not involved in drug-resistance. Hyperthermic treatment induced Hsp70 in all examined cell lines but with different kinetics between drug-resistant and parental cells. Following the treatment with anticancer drugs, Hsp70 was induced only in cisplatin-resistant laryngeal cells. Kinetics of Hsp70 induction (stress-type and cell-type specific) was different in drug-resistant cells as compared to parental cells. The observed alterations in Hsp70 induction in drug resistant and parental cells should be taken into account when combined treatments (i. e. hyperthermia and anticancer drugs) are planned.