Pardo F S, Bristow R G, Taghian A, Ong A, Borek C
Department of Radiation Oncology, Massachusetts General Hospital/Harvard Medical School, Boston 02114.
Proc Natl Acad Sci U S A. 1991 Dec 1;88(23):10652-6. doi: 10.1073/pnas.88.23.10652.
Transfected oncogenes have been reported to increase the radioresistance of rodent cells. Whether transfected nononcogenic DNA sequences and subsequent clonal selection can result in radioresistant cell populations is unknown. The present set of experiments describe the in vitro radiosensitivity and tumorigenicity of selected clones of primary rat embryo cells and human glioblastoma cells, after transfection with a neomycin-resistance marker (pSV2neo or pCMVneo) and clonal selection. Radiobiological data comparing the surviving fraction at 2 Gy (SF2) and the mean inactivation dose show the induction of radioresistance in two rat embryo cell clones and one glioblastoma clone, as compared to untransfected cells. Wild-type and transfectant clones were injected into three strains of immune-deficient mice (scid, NIH, and nu/nu) to assay for tumorigenicity and metastatic potential. Only the glioblastoma parent line and its transfectant clones were tumorigenic. None of the cells produced spontaneous or experimentally induced metastases. Flow cytometric analyses indicated that the induction of radioresistance could not be attributed to changes in cell kinetics at the time of irradiation. Our results show that transfection of a neomycin-resistance marker and clonal selection can impart radioresistance on both normal and tumor cells. The work also indicates that altered radiation sensitivity does not necessarily correlate with changes in cell-cycle kinetics at the time of irradiation, tumorigenicity, or altered metastatic potential. Our findings have critical implications for transfection studies investigating determinants of cellular radiosensitivity.
据报道，转染的致癌基因可增加啮齿动物细胞的辐射抗性。转染非致癌DNA序列并随后进行克隆选择是否会导致产生辐射抗性细胞群体尚不清楚。本系列实验描述了用新霉素抗性标记（pSV2neo或pCMVneo）转染并进行克隆选择后，原代大鼠胚胎细胞和人胶质母细胞瘤细胞选定克隆的体外辐射敏感性和致瘤性。比较2 Gy时存活分数（SF2）和平均失活剂量的放射生物学数据表明，与未转染细胞相比，两个大鼠胚胎细胞克隆和一个胶质母细胞瘤克隆诱导出了辐射抗性。将野生型和转染克隆注射到三株免疫缺陷小鼠（重度联合免疫缺陷小鼠、NIH小鼠和裸鼠）中，以检测其致瘤性和转移潜力。只有胶质母细胞瘤亲本系及其转染克隆具有致瘤性。没有细胞产生自发转移或实验诱导转移。流式细胞术分析表明，辐射抗性的诱导不能归因于照射时细胞动力学的变化。我们的结果表明，新霉素抗性标记的转染和克隆选择可赋予正常细胞和肿瘤细胞辐射抗性。这项研究还表明，辐射敏感性的改变不一定与照射时细胞周期动力学的变化、致瘤性或转移潜力的改变相关。我们的发现对研究细胞辐射敏感性决定因素的转染研究具有关键意义。
