THE RADIOSENSITIVITY OF UVEAL MELANOMA-CELLS AND THE CELL-SURVIVAL CURVE

Background: No study of the radiosensitivity of uveal melanoma cells a nd their survival curve has been published. The purpose of this study was to investigate the sensitivity to different single radiation doses of SP6.5, a human uveal melanoma cell line. Methods: Cells were irrad iated with cobalt-60 at doses from 0 to 1200 cGy. Radiosensitivity was measured by three methods: soft-agar bilayer assay, tritiated thymidi ne incorporation, and bromodeoxyuridine (BrdU) incorporation. Results: The soft-agar bilayer assay, by assessing the colony-forming units, s howed that the D1 value was 470 cGy, the D(q) value was 400 cGy, and t he n value exceeded 10, thus indicating a broad, shoulder and relative radioresistance. The doubling time as estimated by [H-3]thymidine inc orporation was unaffected at doses below 600 cGy, another indication o f radioresistance. BrdU incorporation revealed no significant increase between 0 and 1000 cGy, indicating that the cell cycle was not interr upted. Conclusion: Cell survival, doubling time, and cell phases are p arameters of growth kinetics, and the results suggest that SP6.5 is ra dioresistant and virtually unaffected by single radiation doses lower than 600 cGy. Our data parallel published data for cutaneous melanomas .