Abstract
RNAi is a process to knock down the expression of a specific gene by injecting double stranded RNA and first described in C. Elegance and other organisms. Recently, the application of this technique was extended to mammalian systems by introducing short interfering RNA (siRNA) which consists of double stranded 21 nucleotide RNA with two nucleotide 3'overhangs. In order to apply RNAi to radiation biology, we have succeeded in silencing a NHEJ related DNA-PKcs gene in normal human fibroblasts. As a result, normal cells were changed to radiosensitive cells by reducing the degree of DNA double strand break (DSB) repair (Peng et al 2002). We also have tired to knock down another NHEJ related gene, Ligase IV by using Hemagglutinating virus of Japan envelop (HVJ-E) and a partial success was obtained by increasing the radiosensitivty of normal cells. These results indicate that a strategy of transiently silencing a DSB repair gene may be useful in radiation therapy. [J Radiat Res 44:382 (2003)]
