PILOCARPINE, A SALIVARY-GLAND RADIOPROTECTANT, DOES NOT INHIBIT CYTOTOXIC EFFECT OF GAMMA-RADIATION ON SQUAMOUS-CELL CARCINOMA IN-VITRO

Purpose: Pilocarpine, a salivary stimulant, has been shown to protect salivary glands from gamma-radiation-induced damage during the radioth erapy of head and neck tumors, This study was performed to determine w hether pilocarpine affects the survival of squamous carcinoma cells, l ine SCC-25, following gamma-radiation treatment, Methods and Materials : The survival of squamous carcinoma tumor cells, line SCC-25, followi ng the exposure of cells to pilocarpine at concentration of 0-100 ng/m l given for 0-1 h prior to radiation at dose of 0-20 Gy was determined by an in vitro colony-formation assay, Results: The survival fraction s of SCC-25 cells were identical for the control and pilocarpine-treat ed samples at all tested conditions, Calculated Do and Dq values did n ot depend on the presence of pilocarpine and were not affected by the time of incubation prior to irradiation, Conclusion: Pilocarpine, at c linically relevant concentrations, given to the SCC-25 cells 1 h prior to or at the time of irradiation did not affect survival of SCC-25 ce lls in vitro, Pilocarpine does not sensitize or protect these tumor ce lls from the effects of gamma-radiation, suggesting that this agent sh ould not compromise the tumoricidal effects of radiotherapy. (C) 1997 Elsevier Science Inc.