Shigematsu N, Kawata T, Ihara N, Kawaguchi O, Kutsuki S, Ishibashi R, Kubo A, Ito H
Department of Radiology, School of Medicine, Keio University, 35-Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.
Anticancer Res. 2001 Jan-Feb;21(1A):325-8.
To improve the radiotherapy results, we evaluated etoposide as an effective radiosensitizer by using cultured cell-lines.
Four cell lines having different doubling times (DT) were used: V79 (Chinese hamster fibroblasts, DT = 9 hours), (1), T24 (human bladder cancer, DT = 19 hours) (2), MDA-MB231 (human breast cancer, DT = 25-30 hours) (3) and RMG1 (human ovarian cancer, DT = 50 hours) (4). Cell survival was determined by colony assay and cell cycle analysis was performed by flow-cytometry.
The survival curves showed RMG1 to be the most radiosensitive, followed by MDA-MB231, T24, and V79. V79 was most chemosensitive to etoposide, followed by T24, MDA-MB231 and RMG1. Neither 24-hours exposure to etoposide (< or = 0.05 microgram/ml) or 0.5-h exposure (< or = 1.0 microgram/ml) had any cell killing effect on any of the cell lines used. When the cells were irradiated after exposure to 1 microgram/ml of etoposide for 0.5 hours, no radiosensitization was observed in any of the cell lines except V79. Enhanced radiosensitivity was observed in V79 and T24 cells (which have a relatively short DT) when they were incubated with 0.05 microgram/ml etoposide for 24 hours but no enhanced effect was seen in MDA-MB231 or RMG1 cells (which have a relatively long DT).
It is suggested that a combination of radiation and etoposide may be useful in the treatment of rapidly growing cancer.
为提高放射治疗效果，我们通过培养细胞系评估依托泊苷作为一种有效的放射增敏剂。
使用了四种具有不同倍增时间（DT）的细胞系：V79（中国仓鼠成纤维细胞，DT = 9小时），（1），T24（人膀胱癌，DT = 19小时）（2），MDA - MB231（人乳腺癌，DT = 25 - 30小时）（3）和RMG1（人卵巢癌，DT = 50小时）（4）。通过集落测定法确定细胞存活率，并通过流式细胞术进行细胞周期分析。
存活曲线显示RMG1对辐射最敏感，其次是MDA - MB231、T24和V79。V79对依托泊苷最敏感，其次是T24、MDA - MB231和RMG1。24小时暴露于依托泊苷（≤0.05微克/毫升）或0.5小时暴露（≤1.0微克/毫升）对所使用的任何细胞系均无细胞杀伤作用。当细胞在暴露于1微克/毫升依托泊苷0.5小时后接受照射时，除V79外，在任何细胞系中均未观察到放射增敏作用。当V79和T24细胞（具有相对较短的DT）与0.05微克/毫升依托泊苷孵育24小时时，观察到放射敏感性增强，但在MDA - MB231或RMG1细胞（具有相对较长的DT）中未观察到增强作用。
提示放疗与依托泊苷联合应用可能对快速生长的癌症治疗有用。
