Abstract
Cell survival in response to doxorubicin (Dx) and cis-diammine-dichloroplatinum (cis-Pt) administration, either alone or combined with hyperthermic treatment, was analyzed in human osteosarcoma (U-2-OS), murine melanoma (B16V) and murine leukemia (P388) cell lines and in Dx-resistant sublines derived from B16V and P388. In all cell lines tested there was an enhancement of drug toxicity by hyperthermia. In U-2-OS, the increase was more pronounced for cis-Pt than for Dx. In B16V and in P388, the increase in Dx toxicity was of the same degree in Dx-senstitive and Dx-resistant sublines, whereas heat-induced sensitization to cis-Pt was higher in Dx-resistant sublines than in their Dx-sensitive counterpart. Analysis of the protein pattern in the various cell lines showed that the synthesis of heat-shock proteins induced by heat was not influenced by the combined use of drugs and heat. Moreover, in spite of some differences in the overall protein pattern, no significant differences in the basal levels of heat-shock protein synthesis or in the extent of its induction after heat shock were observed between murine cell lines relatively sensitive to Dx and their corresponding selected resistant cells.
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