放射耐受性结肠癌细胞亚株的建立及其生物学特性

Establishment of radioresistant colorectal cancer cell-subline and its biological characteristics

背景与目的:结肠癌是消化系统的常见肿瘤,放疗是其重要的治疗手段之一。诱导并筛选具有放射耐受性的结肠癌细胞亚株,为研究结肠癌放射耐受的机制提供实验模型。方法:应用梯度递增剂量的γ射线对SW620细胞株进行诱导照射,筛选得到放射耐受细胞亚株SW620/R。观察细胞的形态变化和生长情况,通过CCK8法测定细胞增殖情况,流式细胞仪检测细胞照射的周期及凋亡的变化,克隆形成实验检测细胞克隆形成率和放射敏感性。结果:通过照射剂量梯度递增的诱导方法,成功建立了SW620/R细胞亚株。SW620/R细胞亚株形态与亲本细胞明显不同,并且在高剂量射线照射后仍能继续生长;鉴定实验显示SW620/R细胞亚株与亲本细胞相比倍增时间明显延长,克隆形成率显著下降;在细胞周期上S期的比例显著上升,并且在照射后未出现周期的阻滞现象,同时发现其自发凋亡率显著下降;克隆形成实验显示其放射耐受性明显升高。结论:成功建立了放射耐受的细胞亚株SW620/R,经鉴定其放射敏感性显著降低,且两者在增殖、克隆形成率、细胞周期和自发凋亡上差异有统计学意义(P<0.05)。

Background and purpose： Colorectal cancer is a common tumor of digestive system, radiation therapy is one of the important means of treatment. To explore the mechanism of colorectal cancer cell tolerated to radiation, radioresistant colorectal cancer cell-subline was induced and screened. Methods： Colorectal cancer SW620 cells were repeatedly given individual doses of y-rays to induce radiation resistance. After monoclonal cells being selected and extensively cultured, the cell subline was named SW620/R. Morphological changes and growth of the cells before and after illumination were observed. Cell proliferation was tested by CCK8 assay. The distribution of cells in different stages of the cell cycle and apoptosis were investigated by flow cytometry. The relative radiosensitivities of tumor cells were assessed by standard colony formation assays. Results： SW620/K cells were established by gradient of increasing radiation dose induction method. SW620/R showed significant morphological changes compared with the parent strain SW620. Proliferation experiments showed SW620/R cell line doubling time was longer than SW620, clonogenic capacity decreased significantly. The resistant cells showed a higher percentage of ceUs in S phase and didn＇t appear cell cycle retardation, and the apoptosis rates were also found large differences between two cell lines after irradiation. SW620/R showed lower radiosensitivity by colony-forming assay. Conclusion： Radioresistant colorectal cancer cell subline SW620/R was established and it has lower radiosensitivity than the parental cell line. Two cell lines also have significant differences in proliferation, the rate of colony formation, cell cycle and spontaneous apoptosis （P〈0.05）.