Allam A, Taghian A, Gioioso D, Duffy M, Suit H D
Edwin L. Steele Laboratory of Radiation Biology, Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston 02114.
Int J Radiat Oncol Biol Phys. 1993 Sep 30;27(2):303-8. doi: 10.1016/0360-3016(93)90241-m.
To evaluate the extent of intratumoral heterogeneity of radiation sensitivity in malignant gliomas, by comparing the intrinsic radiation sensitivity of different glioma sublines derived from the same tumor.
The study was performed on five early established malignant gliomas (passage 3-10). Each specimen was quickly cut into three equal pieces (except for one specimen, where only two pieces were obtained). Each piece was processed independently, disintegrated into single cell suspension using a cocktail of enzymes. Survival curve assays, using colony formation as an end-point, were performed for each subline. Comparison between the intrinsic radiation sensitivity of sublines was calculated using the surviving fraction at 2 Gy and the mean inactivation dose as the measured parameters. The DNA content of the cell lines as well as their cell cycle analysis was determined using flow cytometry.
The mean calculated surviving fraction at 2 Gy of all the sublines was 0.37 +/- 0.14, the mean mean inactivation dose was 1.98 +/- 0.63. The intertumoral coefficient of variation for the calculated surviving fraction at 2 Gy of all cell lines was 38%, while that for intratumoral heterogeneity was 25%. Three of the 5 tumors showed a statistically significant difference in the surviving fraction at 2 Gy and mean inactivation dose values of their sublines (p < 0.05). This difference in radiation sensitivity between sublines of the same tumor was not attributed to a difference either in the ploidy status or in the distribution of cells in the cell cycle.
There is a significant intratumoral heterogeneity of radiation sensitivity in some malignant gliomas. This heterogeneity may limit the predictive power of surviving fraction at 2 Gy or mean inactivation dose, especially when their values are based upon a single measurement/single biopsy. In the meantime, this heterogeneity may be a factor in the discrepancy between unexpectedly sensitive tumor cell lines in vitro and their high clinical radiation resistance.
通过比较源自同一肿瘤的不同神经胶质瘤亚系的内在放射敏感性，评估恶性神经胶质瘤瘤内放射敏感性的异质性程度。
对5个早期建立的恶性神经胶质瘤（传代3 - 10）进行研究。每个标本迅速切成三等份（除了一个标本只得到两份）。每份独立处理，使用酶混合物分解成单细胞悬液。以集落形成作为终点，对每个亚系进行存活曲线分析。使用2 Gy时的存活分数和平均失活剂量作为测量参数，计算亚系之间内在放射敏感性的差异。使用流式细胞术测定细胞系的DNA含量及其细胞周期分析。
所有亚系在2 Gy时计算出的平均存活分数为0.37±0.14，平均平均失活剂量为1.98±0.63。所有细胞系在2 Gy时计算出的存活分数的肿瘤间变异系数为38%，而瘤内异质性的变异系数为25%。5个肿瘤中有3个在其亚系的2 Gy存活分数和平均失活剂量值上显示出统计学显著差异（p < 0.05）。同一肿瘤亚系之间放射敏感性的这种差异并非归因于倍性状态或细胞周期中细胞分布的差异。
一些恶性神经胶质瘤存在显著的瘤内放射敏感性异质性。这种异质性可能会限制2 Gy存活分数或平均失活剂量的预测能力，尤其是当其值基于单次测量/单次活检时。同时，这种异质性可能是体外意外敏感的肿瘤细胞系与其高临床放射抗性之间差异的一个因素。
