灵芝酸A对人肝癌细胞的辐射增敏效应的初步研究

本研究旨在初步探讨灵芝酸A(GAA)对人肝癌细胞系HepG2在高LET中子和低LET的γ射线条件下的辐射敏感性的影响及差异。研究中,我们用CCK-8方法检测不同浓度GAA对HepG2增殖抑制作用。选取低浓度(5μmol/L)GAA预处理细胞24 h,分别给予不同剂量的中子辐照或γ射线辐照,分别检测克隆存活率、细胞凋亡和γH2AX蛋白的foci的形成。结果表明:在不加GAA的情况下,高LET中子辐射比低LET的γ射线对细胞产生的凋亡比例高;在添加了GAA后,与未加GAA对照组相比,诱导细胞凋亡的比例明显增加;另外,加GAA处理后,细胞增殖抑制率也随着辐照剂量的增加而增高。即GAA能增加HepG2细胞的辐射敏感性,而在同样GAA剂量下,HepG2细胞对高LET中子辐射比低LET的γ射线更敏感。由此,这项研究说明灵芝酸或可开发成为一种天然辐射增敏剂,从而为癌症特别是肝癌的放疗提供新的辅助治疗方法。

Preliminary Research on the Radiation Sensitizing Effect of Ganoderic acid A on Human Hepatoma Cells

The aim of this study was to investigate the effect of ganoderic acid A (GAA) on the radiosensitivity of human hepatoma cell line HepG2 for high-LET neutron and low-LET gamma-ray radiations. In this research, the CCK-8 method was used to detect the inhibition of proliferation of HepG2 cells treated by GAA. It was found that 5 μmol/L GAA treatment had weak proliferation inhibition effect on HepG2 cells, and so this concentration of GAA was applied to the cells for 24 h in the subsequent experiments. CCK8 assay, clone formation assay, apoptosis assay, and the foci formation of $\gamma $H2AX were detected after irradiated by different doses of either neutron or $\gamma $-ray. The experiments showed that the high-LET neutron irradiation had a higher proportion of apoptosis than the low-LET γ ray irradiation for the cells without GAA treatment, while for the cells with GAA treatment, the proportion of apoptosis also decreased significantly for the cells under $\gamma $-ray irradiation. After treated with GAA, the proportion of induced apoptosis was significantly increased compared to the control group without GAA treatment. Besides, after GAA treatment, the cell proliferation inhibition rate also increased with the increase of irradiation dose. Therefore, these results suggest that GAA can increase the radiosensitivity of HepG2 cells, and HepG2 cells are more sensitive to the high-LET neutron irradiation than low-LET $\gamma $-ray irradiation. As such, this study suggests that GAA not only may serve as a natural radiosensitizer, but also may provide a new radio-therapy method which may be suitable for cancers, or particularly, liver cancers.