^(12)C^(6+)重离子辐照对人肝细胞、肝癌细胞端粒酶活性表达的影响

The changes of telomerase activity of the human hepatocellular cells and carcinoma cells irradiated by ^(12)C^(6+) ions

为探索碳离子束辐照对细胞中端粒酶活性的变化,利用兰州近代物理研究所重离子研究装置(Heavy ion research facility in lanzhou,HIRFL)产生的碳离子(31MeV/μ12C6+),以人肝细胞HL-7702,肝癌细胞SMMC-7721为实验对象,用不同剂量1Gy、2Gy、3Gy、4Gy的重离子分别对两种细胞进行照射,用多聚酶链式反应-银染端粒重复序列扩增法(PCR-telomeric repeat amplification protocol,TRAP-PCR)银染端粒重复序列扩增法检测不同剂量下细胞端粒酶活性的变化。结果显示,人肝细胞HL-7702自身没有端粒酶活性,经1Gy辐照后也没有端粒酶活性,在2和3Gy处出现端粒酶活性,4Gy处端粒酶活性又消失。肝癌细胞SMMC-7721在1～3Gy处随着剂量的增大端粒酶活性升高,在4Gy处又开始下降;在1～3Gy处随着时间的推移端粒酶活性随着时间而加强(p<0.05)。分析得知,重离子辐射可以诱导人肝细胞产生端粒酶活性,也可以改变肝癌细胞的端粒酶活性。端粒酶参与细胞受辐照后DNA单链损伤的修复;辐照后DNA双链断裂导致端粒酶活性减弱。本实验使重离子在辐照治疗中的优势得以体现。

In this paper, the changes of telomerase activity in human liver cells after exposed to the heavy ion radiation were investigated. Irradiation was performed at the Heavy Ion Research Facility in Lanzhou （HIRFL）. The hepatocellular cells HL-7702 and the hepatocellular carcinoma cells SMMC-7721 used as model cell were exposed to ^12C^6＋ irradiation at 0, 1, 2, 3 and 4Gy and formal irradiated cell was re-cultured for 72h and later irradiated cell was re-cultured for 24h and 72h respectively. PCR based on telomeric repeat amplification protocol （TRAP-PCR） method was used to determine the telomerase activity in SMMC-7721 and HL-7702, respectively. It has been found that the HL-7702 cells don＇t express the telomerase activity at 0Gy, 1Gy and 4Gy while the cells exposed to 2Gy and 3Gy express the telomerase activity clearly （P〈0.05）. But when the SMMC-7721 cells are exposed to heavy ionizing radiation at 1-3Gy, the telomerase activity significantly increases in a dose and time dependent manner （p〈0.05）. From this experimental results it can be concluded that heavy ionizing radiation, as a high LET radiation, could induce changes of telomerase activity. It can also be indicated that telomerase participates in the repair process of DNA exposed by heavy ionizing radiation and ^12C^6＋ in tumor therapy could kill tumor cells more efficiently than that by the other low LET rays.