1. 1. Chinese hamster V79 cells were synchronized by mitotic selection or by exposure to hydroxyurea, or excess thymidine. Autoradiography showed that each method yielded a high degree of synchrony. 2. 2. The responses to heat and radiation throughout the cell cycle for the three methods of cell synchronization were qualitatively the same. A complementary cell cycle response for heat and radiation treatments was observed. In S-phase, cells were most heat-sensitive and least radiosensitive while in g1 and G2-phase the opposite was true. The combined heat and radiation treatments resulted in a synergistic enhancement of radiosensitivity through the cell cycle, which was greatest in S-phase, thus eliminating the cell-cycle variation. 3. 3. These data show that cell-cycle responses to heat and radiation are independent of the method of cell synchronization and provide a rationale for overcoming cell-cycle-dependent problems for cell killing in cancer therapy.
All Science Journal Classification (ASJC) codes
- Agricultural and Biological Sciences(all)
- Developmental Biology
- Chinese hamster cells
- cell cycle
- excess thymidine
- mitotic selection