Supraadditive apoptotic response of R3327-G rat prostate tumors to androgen ablation and radiation

被引:105
作者
Joon, DL
Hasegawa, M
Sikes, C
Khoo, VS
Terry, NHA
Zagars, GK
Meistrich, ML
Pollack, A
机构
[1] UNIV TEXAS,MD ANDERSON CANCER CTR,DEPT CLIN RADIAT ONCOL,HOUSTON,TX 77030
[2] UNIV TEXAS,MD ANDERSON CANCER CTR,DEPT EXPT RADIAT ONCOL,HOUSTON,TX 77030
来源
INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS | 1997年 / 38卷 / 05期
关键词
prostate cancer; apoptosis; androgen ablation; radiation;
D O I
10.1016/S0360-3016(97)00303-9
中图分类号
R73 [肿瘤学];
学科分类号
100214 ;
摘要
Purpose: Androgen ablation is often combined with radiation in the treatment of patients with prostate cancer, yet, the optimal sequencing and the mechanisms governing the interaction are not understood, The objectives were to determine if cell killing via apoptosis is enhanced when the combined treatment is administered and to define the relationship of changes in this form of cell killing to tumor volume growth delay, Materials and Methods: Dunning R3327-G rat prostate tumors, grown in the flanks of Copenhagen rats, were used at a volume of approximately 1 cc. Androgen ablation was initiated by castration, and androgen restoration was achieved with 0.5 cm silastic tube implants containing testosterone, Co-60 was used for irradiation, The terminal deoxynucleotidyl transferase (TUNEL) histochemical assay was used to quantify apoptosis, Results: Tumors from intact and castrate unirradiated control rats had average apoptotic indices (percent of apoptotic cells) of 0.4 and 1.0%, respectively. The apoptotic index varied only slightly over time (3 h to 28 days) after castration (range 0.75-1.43%). Irradiation of intact rats to 7 Gy resulted in a peak apoptotic response at 6 h of 2.3%, A supraadditive apoptotic response was seen when castration was initiated 3 days prior to 7 Gy radiation, with peak levels of about 10.1%, When the radiation was administered at increasing times beyond 3 days after castration, the apoptotic response gradually diminished and was back to levels seen in intact rats by 28 days after castration. Tumor volume growth delay studies were consistent with, but not conclusive proof of, a supraadditive effect when the combination was used, Discussion: A supraadditive apoptotic response was seen when androgen ablation and radiation were used to treat androgen sensitive R3327-G rat prostate tumors, This supraadditive effect was dependent on the timing of the two treatments, Further studies are required to more fully define the optimal timing and administration of androgen ablation and radiation. (C) 1997 Elsevier Science Inc.
引用
收藏
页码:1071 / 1077
页数:7
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