Evaluation of cross-resistance between responses to cisplatin, hyperthermia, and radiation in human glioma cells and eight clones selected for cisplatin resistance

Human glioma tells were exposed to stepwise increasing concentrations of ci splatin and given a final, acute, high. concentration treatment of cisplati n. From the surviving cells, eight cisplatin resistant clones were selected . These clones demonstrated a range of cisplatin sensitivities that were re tained in the absence of cisplatin when cells were continually passaged. Th ese cells were tested for cross-resistance to radiation and hyperthermia at 42 and 45 degrees C. The data showed that seven of the eight clones were a lso more radioresistant than the parental line, while one was more radiosen sitive. The degree of cisplatin resistance was not related to the degree of radiation resistance. For hyperthermia at 42 and 45 degrees C, some of the clones were slightly more resistant than the parental line, while one clon e was much more sensitive. This was not the same clone that was radiosensit ive. In conclusion, there was no direct correlation between cisplatin resis tance, radiation resistance, and hyperthermia response, although some of th e clones were resistant to all three treatments. (C) 1999 Wiley-Liss, Inc.