Analysis of Thermotolerance of Cancer by Introduction of Oncogeges

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Hyperthermia is introduced as a new modality of cancer treatment. As thermosensitivity varies to tumors in ten times, all tumors can not be applied to hyperthermia. Oncogenesis of cells is induced by expression of mutated oncogenes. We introduced oncogenes to normal cells and obtained transformed cells, and examined thermosensitivity of cells, analyzing oncogenes which determine thermosensitivity. This study will predict results of cancer treatment by hyperthermia before its treatment, and most effective treatment would be selected.In this study, mouse cultured cells, NIH3T3, were used for normal cells. Following oncogenes were introduced to normal cells and obtained transformed cells : myc, Ki-ras, N-ras, H-ras, int-2, fgr, sis, and src.Thermosensitivity of transformed cells as well as normal cells to 44ﾟC was examined. The transformed cells by Ki-ras showed resistant to hyperthermia. This means that tumors induced by Ki-ras is not desirable to treat by hyperthermia.Thermotolerance induced by the treatment of 44ﾟC,for 15 min was examined for above transformed cells. The thermotolerant ratio analyzed at 4 hour-interval was 2.06 for transformed cells by Ha-ras which was the smallest in examined cells. This means that tumors induced by Ha-ras is desirable to treat by fractionated hyperthermia.