脉冲式低剂量率照射对食管癌细胞及肺组织的影响

目的:评估脉冲式低剂量率照射（RLDR）对食管癌细胞及小鼠正常肺组织的影响。方法:针对人食管癌细胞系EC109和SPF级KM小鼠，进行4种模式照射:常规（CR, 5×2 Gy）、大分割（HR, 2×5 Gy）、PLDR［5×（10×0.2） Gy，当日每分次间隔3 min］、对照组（CG, 0 Gy）。分别于照射前、10 Gy照射后第1、3、5、7天使用CCK-8法检测EC109细胞增殖水平，第4周使用ELISA法检测小鼠血清转化生长因子β1（TGF-β1）水平以及H&E染色观察其肺组织形态。结果:EC109照射后第3天起各实验组的相对吸光度、细胞活力显著低于CG（P<0.05）；照射后第5、7天的CR与PLDR的相对吸光度、细胞活力均显著高于HR组（P<0.05）；CR与PLDR之间均无明显差异（P>0.05）。照射结束后第4周CR、HR小鼠肺组织出现肺泡壁增厚、较多炎细胞浸润，PLDR组小鼠肺组织较正常；且CR与HR小鼠血清TGF-β1水平明显高于CG与PLDR（P<0.05），PLDR与CG无统计学差异（P>0.05）。结论:与CR、HR相比，PLDR在有效抑制食管癌细胞增殖的同时可显著降低放射性肺损伤。

Effects of pulsed low-dose rate radiotherapy on esophageal cancer cells and lung tissues

Abstract: Objective To evaluate the responses of esophageal cancer cells and normal lung tissues in mice exposed to pulsed low-dose rate radiotherapy (PLDR). Methods Human esophageal cancer cell lines EC109 and KM mice (specific pathogen free) in 3 experiment groups were treated with conventional radiotherapy (CR, 5×2 Gy), hypo-fractionated radiotherapy (HR, 2×5 Gy), and PLDR ［5×(10×0.2) Gy, with a beam interval of 3 min］, respectively, and no radiation was delivered in control group (CG). CCK-8 was used to measure EC109 cell proliferation before irradiation and on days 1, 3, 5 and 7 after 10 Gy irradiation. At the 4th week after 10 Gy irradiation, the serum transforming growth factor-β1 (TGF-β1) level was detected using ELISA, and the lung tissue slices were stained with H&E to observe the morphologic changes. Results The relative optical densities and cell viabilities of EC109 cells in experimental groups were significantly lower than those in CG since the 3rd day after irradiation (P<0.05) and on days 5 and 7 after irradiation, the relative optical densities and cell viabilities of CR and PLDR groups were significantly higher than those in HR group (P<0.05) and there was no significant difference in relative optical densities and cell viabilities between CR and PLDR groups (P>0.05). At the 4th week after irradiation, CR and HR results in alveolar wall thickening and more inflammatory cells, but mice exposed to PLDR had normal lung tissues. CG and PLDR groups had similar serum TGF-β1 levels (P>0.05), which were lower than both CR and HR groups (P<0.05). Conclusion Compared with CR and HR, PLDR can significantly reduce radiation-induced lung injury while effectively inhibiting the proliferation of esophageal cancer cells.