PURPOSE: Low dose rate radioemitters, such as 125I, 103Pd, and 89Sr, have been used both for @entity263 . Most normal cells exposed to ionizing radiation characteristically activate cell cycle checkpoints, resulting in cell cycle arrest at the G1/S and G2/M transition points. @entity5 cells are typically quite sensitive to radiation killing late in the G2 phase of the replicative cell cycle. Furthermore, most @entity5 cells accumulating at the G2/M transition point as a result of low dose rate radiation exposure appear to become sensitive to further low dose rate irradiation. For this reason, protracted exposure of @entity5 cells to low dose rate radiation has been proposed to result in increased @entity5 cell killing as compared with brief exposures of @entity5 cells to high dose rate radiation. Since many @entity1 @entity263 contain somatic genome alterations targeting genes which affect the cell cycle and radiation-associated cell cycle checkpoints, we evaluated the effects of low dose rate radiation exposure on the cell cycle and on clonogenic survival for various @entity1 @entity263 cell lines. MATERIALS AND METHODS: @entity1 @entity263 cells from the LNCaP, DU 145, PC-3, PPC-1, and TSU- @entity35 cell lines were exposed to low dose rate (0.25 Gy/hour) or high dose rate (60 Gy/hour) radiation in vitro and then assessed for radiation @entity137 by clonogenic survival assay. Cell cycle perturbations following protracted exposure to low dose rate radiation were evaluated using flow cytometry. RESULTS: For LNCaP cells, low dose rate radiation exposure resulted in an accumulation of cells at both the G1/S and the G2/M cell cycle transition points. For DU 145, PC-3, PPC-1, and TSU- @entity35 cells, treatment with low dose rate radiation triggered G2/M cell cycle arrest, but not G1/S arrest. Unexpectedly, the cell cycle redistribution pattern phenotypes observed, G1/S and G2/M cell cycle arrest versus G2/M arrest alone, appeared to have little effect on low dose rate radiation survival. Furthermore, while PC-3, PPC-1, and TSU- @entity35 cells exhibited increased cytotoxic sensitivity to low dose rate versus fractionated high dose rate radiation treatment, DU 145 and LNCaP cells did not. CONCLUSIONS: Radiation-associated pertubations in replicative cell cycle progression were not dominant determinants of low dose rate radiation killing efficacy in @entity1 @entity263 cell lines in vitro.

Sensitivity of @entity1 XXXX cell lines to low dose rate radiation exposure.

@entity1 :: ('9606', 'Species') :: ['human', 'Human'] @entity137 :: ('MESH:D064420', 'Disease') :: ['cytotoxicity'] @entity263 :: ('MESH:D011471', 'Disease') :: ['prostatic carcinoma', 'prostate cancer', 'prostatic carcinomas', 'local and systemic treatment of prostate cancer'] @entity5 :: ('MESH:D009369', 'Disease') :: ['cancer', 'Cancer'] @entity35 :: ('10116', 'Species') :: ['Pr1']
@entity263 :: (MESH:D011471,Disease) :: ['prostatic carcinoma']
