Comparison of thermoradiosensitization in two human melanoma cell lines and one fibroblast cell line by concurrent mild hyperthermia and low-dose-rate irradiation.
Two human melanoma cell lines, one radioresistant (SK-MEL-3) and one radiosensitive (HT-144), and a normal human fibroblast line (AG1522) were evaluated for thermoradiosensitization of low-dose-rate irradiation by concurrent mild hyperthermia (39-41 degrees C). None of the cell lines expressed chronic thermotolerance during heating at 39-41 degrees C. The SK-MEL-3 cells were the most heat sensitive, while AG1522 and HT-144 cells had the same sensitivity at 39 and 40 degrees C but HT-144 cells were more sensitive at 41 degrees C. All cell lines expressed thermal enhancement of radiosensitivity with heating during irradiation which increased with heating temperature. The SK-MEL-3 cells, which were the most resistant to radiation and demonstrated the greatest repair of sublethal damage (SLD) during low-dose-rate irradiation, had the greatest thermal enhancement of radiosensitivity, while the HT144 cells, which were the most sensitive and expressed little repair of SLD during low-dose-rate irradiation, had the smallest thermal enhancement of radiosensitivity. These data show that concurrent mild hyperthermia during low-dose-rate irradiation may be most efficacious in radiation-resistant tumor cells which express resistance through an enhanced capacity for repair of SLD.
Raaphorst
G P
GP
Ottawa Regional Cancer Centre, Ontario, Canada.
Bussey
A
A
Heller
D P
DP
Ng
C E
CE
D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D005347:Fibroblasts / Q000528:radiation effects*; D006358:Hot Temperature; D006801:Humans; D008545:Melanoma / Q000473:pathology*; D011836:Radiation Tolerance; D013696:Temperature; D014407:Tumor Cells, Cultured