Molecular radiobiologyHypoxia down-regulates DNA double strand break repair gene expression in prostate cancer cells
Section snippets
Prostate cell cultures and hypoxic or CoCl2 treatments
The human malignant prostate cell lines DU145 and PC3 were purchased from American Type Culture Collection (ATCC; Manassas, VA) and the 22RV-1 cell line was a kind gift of Dr Yoni Pinthus (PMH). These cell lines were supplemented with 10% fetal calf serum and 1% l-Glutamine in α-Modified Eagles Medium (MEM), Ham's F12K and RPMI1640, respectively. The normal diploid fibroblast strain GM05757 was purchased from Coriell Cell Repository (Camden, NJ). The SV40-immortalized, benign prostatic
Results
Initial experiments confirmed the gas hypoxic response (0.2 or 2.0% O2 concentrations) in logarithmically-growing normal (normal diploid fibroblast strain, GM05757) and malignant (DU145 prostate cancer) cell cultures. Fig. 1 demonstrates up-regulation of VEGF RNA and increased expression of HIF1α protein at 48 and 72 h for both GM05757 and DU145 cells. Repeated experiments showed similar induction at times ranging from 24 to 72 h for all cultures tested at 0.2% and 2% oxygen gassing conditions
Discussion
To our knowledge, this is the first report that documents gene expression relating to members of the HR and NHEJ pathways following hypoxia in normal, immortalized and malignant cells. We observed decreases in HR-related DNA-dsb repair protein expression within several immortalized and malignant prostate cell lines following gas hypoxia, but not CoCl2-treatment. In our study, the HIF1α-induced gene expression induced by CoCl2 was insufficient to alter RAD51 protein expression. In a previous
Acknowledgements
The authors would like to thank Drs D. Hedley, R.P. Hill and M. Milosevic for helpful discussions and encouragement. These studies are supported by operating grants to R.G.B. from the Terry Fox Foundation (Hypoxia Project Program Grant), Ontario Cancer Research Network PMH Foundation, US Army DOD Prostate Cancer Program and a grant to P.M.G. from the NIH (ES05775). R.S.B. was supported by NIH Medical Scientist Training Grant (GM07205). R.G.B. is a Canadian Cancer Society Research Scientist.
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