Repair of potentially lethal damage: its inhibition by hyperthermia in two human melanoma cell lines with different radio- and heat sensitivities.
The effect of hyperthermia on the inhibition of potentially lethal radiation damage repair (PLDR) was measured in two human melanoma cell lines of differing radiosensitivities. The HT144 cell line is radiation sensitive and has an exponential survival curve, while the SK-MEL-3 line is radiation resistant and has a shouldered survival curve. Both cell lines demonstrated a similar level of PLDR at isosurvival level radiation doses of 2.0 and 10 Gy for the HT144 and SK-MEL-3 lines, respectively. Hyperthermia (40-45 degrees C) could inhibit PLDR in both cell lines. This inhibition was greater in HT144 than in SK-MEL-3 at low temperatures (40 degrees C) and was reversed at higher temperatures (45 degrees C). There was also a sequence dependence of PLDR inhibition which showed a greater inhibition for heat before irradiation at 40 degrees C but the reverse for temperatures of 41 degrees, 43 degrees and 45 degrees C. These data show that hyperthermia can be an effective inhibitor of PLDR in both radiosensitive and resistant cell lines and that the degree of inhibition is not related to radiosensitivity.
Raaphorst
G P
GP
Ottawa Regional Cancer Centre, Ont, Canada.
Mao
J P
JP
Ng
C E
CE
D004307:Dose-Response Relationship, Radiation; D006361:Heating; D006801:Humans; D006979:Hyperthermia, Induced; D008545:Melanoma / Q000473:pathology / Q000532:radiotherapy* / Q000628:therapy*; D011836:Radiation Tolerance; D014407:Tumor Cells, Cultured / Q000528:radiation effects