Effects of 2, 2-dimethylthiazolidine hydrochloride on the radiosensitivity of transplantable mouse tumors

This paper presents the effects of 2,2-dimethylthiazolidine-HCI (DMTD), a radioprotective agent, on cancer radiosensitivity. The weights of tumor masses of sarcoma 180, measured 1d after the completion of irradiation, showed no difference between DMTD-protected and nonprotected groups. The regression of S180 was observed in 2/7 DMTD-protected mice 2 wk after the completion of exposure. Meanwhile, the average weights (g) of tumor masses of S180 were 4.6±(SD) 2.8 and 8.4±2.4 (P<0.05) in DMTD-protected and nonprotected mice, 14.1±3.0 and 18.3±4.6. (P<0.05) in DMTD-treated and controlled mice, respectively after death. The death rates (%) of Ehrlich ascites tumor cells (EAC) were 16.5±10.6 and 7.6±4.0 (P<0.01) in DMTD-protected and nonprotected mice, respectively, and 9.4±4.7 and4.7±2.9 (P<0.01) in DMTD-treated and controlled mice, respectively. The weights (g) of ascitic fluid were 1.7±1.4 and 2.4± 1.5 (P>0.05) in DMTD-protected and nonprotected mice, respectively, 6.5±2.8 and 7.4±3.5 (P>0.05) in DMTD-treated and controlled mice, respectively. DMTD showed no significant effect on the weight of spleen and the average survival time in reticular-cell leukemia of mice (L615). These data suggest that DMTD neither decreased the radiosensitivity of S180, EAC and L616, nor enhanced the growth of these transplantable mouse tumors. On the contrary, DMTD exerted some inhibitory effects on tumor cell growth of S180 and EAC, and rendered the tumor cells more sensitive to irradiation.