【摘要】 目的：研究及探讨快中子及X射线诱导人直肠癌细胞凋亡及其相关基因表达。方法：不同剂量X射线（0、2、4、6、8、10Gy）及具有同等放射生物学效应的相当于X射线1／3剂量的不同剂量快中子（0、0．67、1．34、2．01、2．68、3．34Gy）照射细胞，于37℃孵育6小时24小时48小时72小时后，进行Hoechest 33 342荧光染色，观察细胞凋亡形态并计数凋亡指数AI（凋亡细胞的百分数）；用电子显微镜观察凋亡细胞特有的形态学特征；此外，我们分别对不同剂量（0、2、4、6、8、10Gy） X射线及快中子（0、0．67、1．34、2．01、2．68、3．34Gy）照射后24小时的细胞用免疫组化方法进行基因表达（p53及bcl－2）的检测。结果：不同剂量X射线和快中子照射的细胞凋亡指数随着照射剂量和受照时间的延长而逐渐增加，在同一时间点，快中子诱导的细胞凋亡水平明显高于X射线；不同剂量X射线照射后的细胞，较阳性对照组，p53基因表达下调明显，bcl－2基因表达下调不明显；不同剂量快中子照射后的细胞，p53及bcl－2基因表达下调均不明显。结论：高能X射线和快中子诱导人直肠癌细胞的凋亡具有明确的时间－剂量相关性，随着受照后时间的延长和剂量的逐渐增大，凋亡指数渐趋升高，无明显变缓之势；快中子照射人直肠癌细胞，与X射更多还原

【Abstract】 Purpose To investigate apoptosis induced by x－ray fast－neutron－ray and its relevant gene expression in human rectal carcinoma cell line． Materials and Methods Cells were radiated by various dose of x－ray 0Gy 2Gy 4Gy 6Gy 8Gy 10Gy and that of fast－neutron－ray 0Gy 0．67Gy 1．34Gy 2．01Gy 3．34Gy which had the same effects of radiobiology as one－third of the equivalent dose of x－ray． After that cells were incubated for 6h 24h 48h72h in the constant temperature of 37℃． Fluorescent staining of DNA was used to detect the relation between apoptotic index percentage of apoptotic cells and irradiation dose of x－ray and fast－neutron－ray as the same time after radiation． The special morphological feature of apoptotic cells was observed with electron microscope． In addition we detected gene expression for cells radiated by various dose of x－ray 0 2 4 6 8 10Gy and fast－neutron－ray 0 0．67 1．34 2．01 2．68 3．34Gy． Results AI of cells radiated by various dose of x－ray and fast－neutron－ray gradually increased with the increase of the dose and time in human rectal cancer cell line． Furthermore at the same point of time AI of cells induced by fast－neutron－ray was higher than that induced by x－ray． For cells radiated by various dose of x－ray down－regulated expression of p53 protein was observed significantly but bel－2 protein was not． For cells radiated by various dose of fast－neutron－ray it was not observed that the significant down－regulated expression of p53 protein and bel－2 protein． Conclusion Our results indicate that the apoptic response induced by x－ray and fast－neutron－ray in rectal carcinoma cell line is time－dose dependent． The more time and dose increased the more AI increased with no appearance of plateau observed． The apoptotic response induced by fast－neutron－ray is higher than that by x－ray in human rectal cancer cell line． Additionally down－regulated expression of p53 protein and bel－2 protein has shown that p53 tumor suppressor gene and bel－2 protooncogene are both involved in the control of apoptotic gene expression．更多还原