人肝癌细胞BEL-7402非常规照射模式生物效应探讨

目的 探讨不同照射模式对人肝癌细胞株BEL-7402生物效应变化影响及其与人肝细胞株QSG-7701放射敏感度差异。方法 6MV X线两种模式照射BEL-7402细胞(包括0、1、2、3、5、7、9、10Gy共8个吸收剂量点，剂量率3Gy/min)：(1)急速照射组，照射完成时间0~4min；(2)模拟三维适形照射组：照射完成时间：12~15min。成克隆分析法计算存活分数，多靶单击数学模型拟合曲线，求出SF2、D0、Dq等参数值；6MV X线单次5Gy照射体外培养的BEL-7402、QSG-7701 细胞, 采用MTT 比色法、流式细胞术测定细胞受照后不同时间存活率、凋亡率、细胞周期。结果 BEL-7402细胞模拟急速照射组和三维适形照射组D0、Dq、SF2值分别为1.78和1.69、1.45和1.54、0.625和0.654；QSG-7701 细胞照后24 h 凋亡率最高(18 %)，而BEL-7402细胞照后12h凋亡率最高(32 %)，存活率最低(65%)，两株细胞照后12 h 凋亡率和存活率差异最大（P<0.01）。结论 三维适形照射模式下分次照射时间延长，生物效应下降；BEL-7402及QSG-7701两株细胞在照后存在放射敏感度差异。

Preliminary Study of Radiobiological Effects on Human Hepatocarcinoma Cells BEL-7402 by Different Irradiation Model

Objective To investigate the radiobiological effects of two irradiation protocols on human hepatocarcinoma cells BEL-7402 and hepatic cells QSG 7701. Methods BEL-7402 cells were irradiated by total doses of 0 Gy,1 Gy,2 Gy,3 Gy,5 Gy,7 Gy,9 Gy,10Gy at a dose rate of 3Gy/min. Two different delivery patterns were acute irradiation model with the fraction delivery time was 0~4 min; and 3-Dimensional conformal radiation therapy (3DCRT) model with the fraction-delivery-time was lasted 13~15 min. The surviving fractions were determined by classical colony forming assay. The radiobiological parameters were calculated, and cell survival curves were plotted according to “the single hit multi-target model”. The survivability, apoptosis and cell cycles of BEL-7402 and QSG-7701 cells irradiated by 6MV X-ray with a single dose of 5 Gy, were assessed by methyl thiazole tetrazolium (MTT) assay and flow cytometry ( FCM ). Results The values of D0, Dq, SF2 of BEL-7402 cell line in acute irradiation pattern and 3DCRT irradiation pattern were 1.69 and 1.78, 1.45 and 1.54, 0.625 and 0.654 respectively. The number of apoptotic BEL-7402 cells reached a peak (32%) and showed a lowest survival (65%) at the 12h after irradiation, while irradiated apoptotic rate in QSG-7701 cells showed highest (18%) at the 24h. Apoptosis and survival between the two cell lines at 12h induced by radiation were significant different（P<0.01）. Conclusion The radiobiological effectiveness were able to be influenced by prolonged fraction delivery time for 3DCRT. Radiosensitivity was markedly various from cancer and normal cellular line.