Karuri A, Mukherji S
Department of Biophysics, Chittaranjan National Cancer Research Centre, Calcutta, India.
Neoplasma. 1989;36(3):321-6.
The murine ascites sarcoma 180 cells were used to test the in vivo effectiveness of mitomycin C (MMC) and gamma-radiation applied in combination. The action of intraperitoneal administration of MMC and/or whole-body gamma irradiation on sarcoma 180 tumor bearing Swiss albino mice was investigated by studying the template activity of isolated tumor chromatin. The Km value for transcription of 10 Gy-irradiated chromatin was found to decrease with time implying an increase in the template efficiency with respect to that of the unirradiated control. Maximum decrease in Km was observed after 24 h of irradiation. MMC treatment (7 mg/kg body weight of mouse) for 18 h resulted in an inhibition of the transcription rate. Severe inhibition in the template activity was found when cells were subjected to MMC treatment 18 h prior to irradiation with 10 Gy. Susceptibility of tumor chromatin to DNase II followed the same pattern as observed in the case of transcription indicating structural alteration of the treated chromatin. The data showed that DNA damage and its consequences produced in the ascites cells by prior treatment of MMC were not repaired during the 18 h period after which the application of radiation enhanced cytotoxicity.
使用小鼠腹水肉瘤180细胞来测试丝裂霉素C（MMC）与γ射线联合应用的体内有效性。通过研究分离的肿瘤染色质的模板活性，研究了腹腔注射MMC和/或全身γ射线对荷肉瘤180的瑞士白化病小鼠的作用。发现10 Gy照射染色质转录的Km值随时间降低，这意味着相对于未照射的对照，模板效率有所提高。照射后24小时观察到Km的最大降低。MMC处理（小鼠体重7 mg/kg）18小时导致转录速率受到抑制。当细胞在10 Gy照射前18小时接受MMC处理时，发现模板活性受到严重抑制。肿瘤染色质对DNase II的敏感性与转录情况遵循相同模式，表明处理后的染色质发生了结构改变。数据表明，MMC预处理在腹水细胞中产生的DNA损伤及其后果在18小时内未得到修复，在此之后施加辐射增强了细胞毒性。
