RNAi-mediated targeting of non-coding and coding sequences in DNA repair gene messages efficiently radiosensitizes human tumor cells
Menée in vitro, cette étude montre que l'utilisation d'ARNs interférents ciblant les ARNs messagers transcrits des régions codantes ou non codantes de gènes impliqués dans la réparation de l'ADN peut sensibiliser les cellules tumorales aux rayonnements ionisants
Human tumor cell death during radiotherapy is caused mainly by ionizing radiation (IR)-induced DNA double strand breaks (DSBs), which are repaired by either homologous recombination repair (HRR) or non-homologous end-joining (NHEJ). Although siRNA-mediated knockdown of DNA DSB repair genes can sensitize tumor cells to IR, this approach is limited by inefficiencies of gene silencing. In this study, we demonstrate that combining an artificial microRNA (amiR) engineered to target 3'-untranslated regions of XRCC2 (a HRR factor) or XRCC4 (a NHEJ factor) along with an siRNA to target the gene coding region can improve silencing efficiencies to achieve more robust radiosensitization than single approaches alone. Mechanistically, the combinatorial knockdown decreased targeted gene expression through both a reduction in mRNA stability and a blockade to mRNA translation. Together, our findings establish a general method of gene silencing that is more efficient and particularly suited for suppressing genes that are difficult to downregulate by amiR or siRNA based methods alone.
Cancer Research 2012