单次、分次照射与125I 粒子低剂量率照射对人喉鳞癌 Hep2细胞的抑制作用

目的：探讨125I 粒子持续低剂量率照射与分次照射、单次照射对人喉鳞癌细胞 Hep2的抑制作用及其作用机制。方法实验分为无照射对照组（Ctrl 组）、单次照射组（SDR 组）、分次照射组（FDR 组）和125I 粒子持续低剂量率照射组（125I-CLDR 组）四组。采用细胞克隆形成实验法检测 Hep2细胞在不同照射条件下细胞克隆的形成能力；用流式细胞仪检测细胞凋亡和细胞周期阻滞情况；用蛋白印迹法检测不同照射条件后 Hep2细胞总γ-H2AX、CyclinB1、Caspase3蛋白表达的变化。结果经2 Gy、4 Gy、6 Gy 的剂量照射，125I-CLDR 组 Hep2细胞克隆形成率均低于 SDR 组和 FDR 组。经4 Gy 的剂量照射后，125I-CLDR 组 Hep2细胞出现 G2/M 期阻滞，且阻滞效应较 SDR 组及 FDR 组的细胞强；125I-CLDR 组 Hep2细胞的凋亡比例明显高于 SDR 组及 FDR 组；三个照射组γ-H2AX、CyclinB1、Caspase3、NF-κB、P21和 Cdk1的表达水平上调，125I-CLDR 组 p-Cdc25c 蛋白表达水平低于 SDR 组和 FDR 组。结论在本实验条件下，125I 粒子持续低剂量率照射较单次照射、分次照射能够诱发更多 Hep2细胞出现 DNA 损伤、引起持续的 G2/M 期阻滞、诱导细胞凋亡并抑制细胞的再增殖。

The inhibition effects of different irradiation methods on human laryngeal squamous carcinoma cell line Hep2

Objective To investigate the inhibition effects of different irradiation methods on the proliferation of Hep2, which is the human laryngeal squamous carcinoma cell line, and the corresponding mechanisms. Method Four groups of patients receiving different irradiations were compared in our experiment, which were non-radiation control group (Ctrl), high dose rate single dose radiation group (SDR), high dose rate fractionated dose radiation group (FDR), and iodine-125 seeds continuous low dose rate radiation group (125I-CLDR), respectively. Colony forma-tion assay was used to determine the radiosensitivity of Hep2 cells to each radiation, and flow cytometry was applied for detecting cell apoptosis and cell cycle arrest, while the protein expression levels of γ-H2AX, CyclinB1 and Cas-pase3 were detected with Western blot. Result The capability of clone formation of Hep2 cells after 2 Gy, 4 Gy, 6 Gy irradiation was lower in 125I-CLDR group compare with SDR and FDR group. After 4 Gy irradiation, 125I-CLDR induced the most significant Hep2 cells arrest effect of G2/M among the three groups. And the highest cell apoptosis proportion was seen in 125I-CLDR group either. The expression levels of γ-H2AX, CyclinB1, Caspase3, NF- κB, P21 and Cdk1 increased among three treatment groups. While p-Cdc25c expressed the least in 125I-CLDR group. Conclu-sion In the context of this study, 125I-CLDR obviously reduces cellular DNA repair capacity, induces cell apoptosis and G2/M arrest, and inhibits cell reproliferation.