放射敏感性与染色体诱导易位的线形关系及其应用研究

应用荧光原位杂交（FISH）方法，研究人类恶性肿瘤细胞放射敏感性与照射后染色体易位畸变关系及其临床应用的可行性。采用3个放射敏感性不同的人类恶性肿瘤细胞株：鼻咽鳞癌（CNE）、肺腺癌（SPC－A1）和乳腺腺癌（MCF－7）。用常规集落形成方法，测定不同照射剂量下、不同敏感性肿瘤细胞的存活率。经秋水仙素阻断细胞分裂周期，低渗、固定等常规染色体制片过程和采用2，8号染色体涂染探针及FISH方法，测定照射后24h肿瘤细胞2，8号染色体内在的和辐射诱导的易位畸变量。结果发现，未照射的对照细胞内，2，8号染色体都存在不同程度的内在易位畸变。经分别照射2，4，6Gy后24h,CNE,SPC-A1和MCF－7细胞诱导生成的残存染色体易位畸变与照射剂量相关性强，能够反映细胞的放射敏感性；此外，所有细胞株中诱导生成的2，8号染色体易位畸变与细胞存活率也存在良好相关性，相关系数分别为0.97和0.98。该结果同时表明照射诱导易位畸变存在染色体簇性，与染色体大小无关。由此可见，诱导的残存染色体易位畸变与照射剂量呈线形关系。采用FISH方法计数照射诱导的残存染色体易位畸变，在预测不同的肿瘤细胞放射敏感性差异方面具有重要的临床意义。

The Linear Relationship Between Chromosome Induced-Translocation And Radiosensitivity of Human Tumor Cells

Fluorescence in situ hybridization (FISH) was used to investigate the relationship between induced-translocation of chromosome af ter radiation and radiosensitivity of tumor cells and to see whether the r esult can be used to predict the radiosensitivity of human tumor cell lines, and thereby to provide a potential means of assessing cell radiosensitivity. Three human cell lines with different radiosensitivity, i.e. a nasopharyngeal cell lin e (CNE), a lung adenocarcinoma cell line (SPC-A1) and a breast adenocarcinoma ce ll line(MCF-7), were used and assessed for clonogenic cell survival after radia tion with 1, 2, 4, 6 and 8 Gy and for radiation-induced aberrations in two chro mosomes(number 2 and 8) 24 h after irradiation with 2, 4and 6 Gy . The number of radiation-induced aberration in chromosome 2 and chromosome 8 remaining 24 h after irradiation could reflect the radiosensitivity of th e cells, and there was a good relationship between induced aberrations in chromo some 2 and chromosome 8 and cell survival for all the three cell lines with the related coefficients 0.97 and 0.98 respectively. Thus, the induced-aberration, observed by means of the method ofFISH, can be used to predict the radiosensitivity oftumor cells.