@misc{oai:repo.qst.go.jp:00068927,
 author = {Yu, Dong and Sekine, Emiko and Fujimori, Akira and Okayasu, Ryuichi and 于 冬 and 関根 絵美子 and 藤森 亮 and 岡安 隆一},
 month = {Apr},
 note = {In order to understand the role of BRCA2 protein in homologous recombination (HR) repair and radio-sensitization, we utilized RNA interference (RNAi) strategy to knock down the expression of this protein in HeLa cells. HR and non-homologous end joining (NHEJ) are the two major pathways for repair of DNA double strand breaks (DSBs) in mammalian cells. HR pathway is known to work in late-S and G2 phases of the cell cycle, while NHEJ does not seem to depend on the cell cycle. HeLa cells were transfected with BRCA2 siRNA (Qiagen) as well as negative-control siRNA for 48 hours. After confirming the downregulations of BRCA2 mRNA by quantitative RT-PCR and the protein level by western blotting, the radiosensitivity of transfected Hela cells was examined by colony formation assay and DNA DSB repair was measured by constant field gel-electrophoresis technique. Immuno-staining method was used to study the expression and phosphorylation of key DSB repair proteins such as Rad51 (HR pathway), DNA-PKcs (NHEJ pathway) and gamma-H2AX. Our data clearly demonstrate that downregulation of BRCA2 leads to radio-sensitization through inhibition of DSB repair. Since Rad51 foci formation was significantly affected by BRCA2 siRNA without affecting DNA-PKcs phosphorylation, BRCA2 appears to play a major role in the HR pathway, but not in the NHEJ pathway. These results suggest the possibility of using BRCA2 siRNA as a new radiosensitizer for circulating tumor cells., AACR Annual Meeting 2007},
 title = {Down regulation of BRCA2 enhances tumor radio-sensitivity through inhibition of homologous recombination repair},
 year = {2007}
}