诱导建立乳腺癌MCF-7放射耐受细胞亚株的实验研究

Inducing and Establishing Cell Sublines with Radiation Resistance in Human Breast Cancer MCF-7 Cells

目的:探索诱导并建立人乳腺癌MCF-7放射耐受细胞亚株的体外实验方法。方法:体外培养MCF-7细胞株,应用梯度递增的X线对MCF-7进行诱导照射,照射剂量达到59Gy时,得到放射耐受细胞亚株(MCF-7R),扫描电镜和透射电镜观察亲本株MCF-7与放射耐受细胞亚株MCF-7R细胞超微结构,流式细胞仪检测其细胞周期分布,集落形成实验检测其放射敏感性,并计算存活分数,多靶单击模型拟合细胞存活曲线。结果:与MCF-7相比,MCF-7R外形及细胞器均出现明显改变;G_2/M期比例明显降低;(13.32%vs.9.43%)放射敏感性参数SF_2即照射2 Gy时的细胞存活分数升高34%(P<0.001),准域剂量Dq值由2.261 Gy升高至3.695 Gy(P<0.05),平均致死剂量D_o值由1.215 Gy升高至1.834 Gy(P<0.05)。结论:照射剂量梯度递增法是可行的建立人乳腺癌放射耐受细胞亚株的方法,得到的放射耐受亚株细胞形态及细胞生物学特性与亲本株细胞相比较有明显差异。

Objectives： To induce and establish breast cancer cell sublines with radiation resistance in MCF-7. Methods： Breast cancer cell MCF-7 cells were repeatedly given individual doses of X-rays with liner accelerator to induce radiation resistance with adequate dosage, The intracellular ultrastructure of the strains was observed through scanning electron microscopy and transmission electron microscopy. The cell cycle distribution was examined by flow eytometry. Cell radiosensitivity as assayed by colony formation assay, and the survival fraction was calculated. The multi-target model that fit the cell survival curve was selected. Results： At the same irradiation condition and radiation dose, the radio-resistant sub-cell MCF-7R showed significant morphological changes, such as shape and organelles, compared with the parent strain MCF-7. Cell cycle analysis showed that MCF-7R had lower Percentage G2/M and slower proliferation tendency. Cell clone analysis demonstrated that MCF-7R had greater SF2 （ survival fraction after 2 Gy irradiation, increased by 34 %. P 〈 0.001 ）, Dq （ 2.261 to 3.695, P 〈 0.05 ） and Do （ 1.215 to 1.834, P 〈 0.05 ）. Conclusion： The method of radiating cell step by step and repeatedly is viable to establish radio-resistant breast cancer sub-cell line, and the radioresistant sub-cell line MCF-TR has conspicuous changes in morphological and biological characteristics compared with the parental cell line.