Combined cytotoxicity effect of hyperthermia and anthracycline antibiotics on human tumor cells.

The effects of temperature on the anthracycline antibiotics-induced cell kill of DND-1A human malignant melanoma (MM) and DND-39A Burkitt's lymphoma (BL) cell lines were studied by means of a clonogenic assay. The two cell lines differed in sensitivity when exposed to heat: The MM cells were unaffected by hyperthermia (42 degrees C), whereas BL cells were sensitive to this temperature. With the MM cells, hyperthermia potentiated the cytotoxic effects of doxorubicin (ADM), daunorubicin, mitoxantrone (DHAD), and quelamycin but did not enhance that of aclacinomycin (ACM). Conversely, the exposure of cells to the anthracycline compounds at 0 degree C resulted in almost complete disappearance of cell kill effects except with ACM; ACM retained substantial cell kill effects even at the given low temperature. For BL cells, ADM- or DHAD-induced cell lethality was also potentiated by hyperthermia; ACM produced only additive cell kill. At 0 degree C, ACM's effects virtually disappeared. These data indicate that human tumor cell lines have a substantial variety in heat sensitivity and that not every anthracycline antitumor agent is potentiated by temperature. ACM's thermoresponse is unique among anthracycline antibiotics studied. Additionally, it was shown that normothermic cell kill by ADM was not affected by hyperthermic preheating; however, preheating of appropriate duration produced important influence on subsequent hyperthermic ADM-induced cell kill.