The Studies of Radiation Sensitivity of Tumor Cells by Using Determinating Method of DNA Damage and Repair

The effects of ⁶⁰Co r-rays and its combination with hyperthermia on DNA strand breaks and their repair in L5078Y cells were studied using alkaline elution technique. When cells were heated at 43℃ for 30 min there was obvious inhibition of its repair in DNA damage caused by r-irradiation. The inhibiting effect of hyperthermia before irradiation was better. The effects of radiation on DNA strand breaks and its repair in HL-60 cells and HL-60(VCR) cells were analyzed by using technique of hydroxylapatite chromatography. The extent of DNA strand breaks in HL-60 cells and HL-60(VCR) cells induced by irradiation was no markedly different. But the repair ratio of strand breaks in HL-60(VCR) cells was higher than that in HL-60 cells, The difference was obvious. The results suggest that the heterogeneity of radiosensitivity of leukemia cells is correlated with its drug resistance.