Thalidomide radiosensitization of normal murine hematopoietic but not squamous cell carcinoma or multiple myeloma tumor cell lines

Background: Thalidomide (TL), due to its antiangiogenic effects, has been postulated to be a potential radiosensitizer of multiple myeloma and squamous tumors in vivo. Materials and Methods: To determine whether TL was a radiosensitizer, 32D cl 3 cells (hematopoietic progenitor) as well as SCC-VII (squamous cell carcinoma), OPM1 or OPM2 (multiple myeloma) tumor cells were irradiated to doses ranging from 0 to 8 Gy and then plated in 0, 50 or 150 mu M TL in each of three protocols: i) 1 hour before irradiation; ii) 1 hour before irradiation and also in medium following irradiation; or iii) placed in TL containing medium following irradiation. Results: Using 150 mu M TL (which did not stimulate cell growth) the 32D cl 3 cells had increased radiation sensitivity compared to the control irradiated cells. In contrast, the SCC-VII, OPM1 or OPM2 cells showed no detectable radiosensitization when incubated in TL before, during or after irradiation compared to the control irradiated cells. Conclusion: These results demonstrated that TL may be a selective radiosensitizer.