van Rijn J, van den Berg J, Wiegant F A, van Wijk R
Department of Radiotherapy, Free University Hospital, Amsterdam, The Netherlands.
Radiat Environ Biophys. 1995 Aug;34(3):169-75. doi: 10.1007/BF01211544.
In this study we compared sensitization to x-rays by heat or sodium arsenite and the effect of an induced heat or arsenite resistance on radiosensitization. Treatment of Reuber H35 hepatoma cells with either heat or arsenite causes a dose-dependent radiosensitization. Based on a comparison of isosurvival doses for arsenite and heat, arsenite causes a stronger enhancement of the radiosensitivity. Radiosensitization increases exponentially with increasing sensitizer dose. It is gradually lost when the time interval between irradiation and treatment with heat or arsenite increases, depending on the treatment sequence. For x-rays prior to heat, radiosensitization disappears approximately twice as fast as in the reverse case. Arsenite radiosensitization shows approximately the same kinetics for an isoeffective combination, but slightly longer times are needed for the complete clearance of the interaction. As with heat, an exposure to arsenite induces a stress response in cultured cells which results in the development of an increased tolerance towards a second exposure. Heat and arsenite induce self- as well as cross-tolerance. The reduction in arsenite or heat toxicity in tolerant cells is correlated with a reduction in radiosensitization. The mechanisms for heat and arsenite cytotoxicity appear to be different. A combination of non-toxic doses of heat and arsenite has a synergistic effect on the cytotoxicity. One hour incubation with 0.02 mM arsenite at 41 degrees C has the same cytotoxicity as 0.2 mM after 3 h incubation at 37 degrees C, and the amount of radiosensitization induced by these treatments is approximately the same.
在本研究中，我们比较了热或亚砷酸钠对X射线的致敏作用以及诱导产生的耐热性或抗砷性对放射致敏作用的影响。用热或亚砷酸钠处理鲁伯H35肝癌细胞会导致剂量依赖性放射致敏。基于对亚砷酸钠和热的等存活剂量的比较，亚砷酸钠对放射敏感性的增强作用更强。放射致敏作用随致敏剂剂量的增加呈指数增加。当照射与热或亚砷酸钠处理之间的时间间隔增加时，放射致敏作用会逐渐消失，这取决于处理顺序。对于先热后X射线照射的情况，放射致敏作用消失的速度大约是相反情况的两倍。对于等效组合，亚砷酸钠放射致敏作用表现出大致相同的动力学，但完全消除相互作用所需的时间略长。与热一样，暴露于亚砷酸钠会在培养细胞中诱导应激反应，从而导致对第二次暴露的耐受性增加。热和亚砷酸钠会诱导自身耐受性以及交叉耐受性。耐受性细胞中亚砷酸钠或热毒性的降低与放射致敏作用的降低相关。热和亚砷酸钠的细胞毒性机制似乎不同。无毒剂量的热和亚砷酸钠组合对细胞毒性具有协同作用。在41℃下用0.02 mM亚砷酸钠孵育1小时与在37℃下用0.2 mM亚砷酸钠孵育3小时具有相同的细胞毒性，并且这些处理诱导的放射致敏作用量大致相同。
