持续低剂量率照射对化学致癌物质诱发小鼠肺肿瘤的干预作用

The interfering effect of persistent low dose rate irradiation on tumor formation in mice by chemical carcinogen

目的 研究致癌物氨基甲酸己酯作用下 ,持续低剂量率γ射线照射 (PLDRR)对两代小鼠肺肿瘤形成的干预作用和肿瘤细胞增殖、p5 3抗癌基因表达的调节。方法 2 0 μGy min× 42d1 3 7Csγ射线照射两代昆明种小鼠 ,化学致癌物单次腹部皮下注射量为 :2 0 0 0mg kg ,观察肺肿瘤的形成 ,免疫组化分析肺肿瘤组织PCNA和p5 3抗癌基因。结果 PLDRR并未明显干预化学致癌物对肺肿瘤的形成 ,实验组与对照组肺肿瘤发生率分别为 94%和 95 83 % ,差异无显著性 (P >0 0 5 χ2 =0 0 0 4) ,但在PLDRR下受精、怀孕及出生后仍在该环境中生长发育的仔代小鼠肺肿瘤发生率仅为 5 6 6 0 % ,明显低于祖代小鼠肺肿瘤发生率 (P <0 0 1χ2 =2 0 81) ,瘤体直径和平均发瘤数也低于祖代小鼠。仔鼠突变型p5 3蛋白产物和PCNA的表达显著下降。结论 PLDRR可诱发仔代小鼠对肺肿瘤的“适应性反应” ,仔代小鼠肿瘤细胞增殖能力降低。

Objective\ This paper studies the interfering effect of persistent low dose rate irradiation of γ\|rays on the formation of lung tumors in mice of two generations and on the regulation of the proliferation of tumor cells as well as p53 gene under the effect of ethyl carbamare,a chemical carcinogenic substance. Methods Kunming mice were subjected to irradiation of 1\^20 Gy 137 Cs γ rays(dose rate:20 μGy/min) and the single abdominal subcutaneous injection dose of chemical carcinogentic substance was 2 000 mg/kg.The formation of lung tumor cells was observed and lung and lung tumor tissue PCNA and p53 anti\|cancer gene were analysed by means of immunohistochemical method of biotin marker. Results\ Persistent low dose irradiation did not markedly interfere with the effect of chemical carcinogenic substances on formation of lung tumor and the incidence of lung tumor of mice in the experimental and control group was 94% and 95 83%,respectively,with no significant difference (χ\+2=0 004, P >0 05).The incidence of tumor in the offspring mice,whose sterilization,pregnancy and growth were all under persistent low dose rate irradiation,was 56 6%,being evidently lower than that of parental mice (χ\+2=20 81, P <0 01).In addition,the diameter of tumor and the average number of tumors in offspring mice was also smaller than those of parental mice,the mutation of p53 in offspring mice and the expression of PCAN were greatly reduced. Conclusion\ Persistent low dose rate irradiation can induce an “adaptive reaction” of offspring mice to lung tumor for mation and reduce the proliferation of tumor cells in offspring mice.\;