title: RNAi-mediated targeting of noncoding and coding sequences in DNA repair gene messages efficiently radiosensitizes human tumor cells.
abstract: Human tumor cell death during radiotherapy is caused mainly by ionizing radiation (IR)-induced DNA double-strand breaks (DSB), which are repaired by either homologous recombination repair (HRR) or nonhomologous 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 show that combining an artificial miRNA (amiR) engineered to target 3'-untranslated regions of XRCC2 (an HRR factor) or XRCC4 (an NHEJ factor) along with an siRNA to target the gene coding region can improve silencing efficiencies to achieve more robust radiosensitization than a single approach 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.
authors.affiliation: Department of Neurosurgery, Provincial Hospital affiliated to Shandong University, Shandong University, Jinan, China.
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Zheng
authors.forename: Wooi Loon
authors.initials: WL
authors.lastname: Ng
authors.forename: Xiangming
authors.initials: X
authors.lastname: Zhang
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Olson
authors.forename: Chunhai
authors.initials: C
authors.lastname: Hao
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Curran
authors.forename: Ya
authors.initials: Y
authors.lastname: Wang
mesh_terms: D020413:3' Untranslated Regions; D045744:Cell Line, Tumor; D004260:DNA Repair / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D020868:Gene Silencing; D018390:Gene Targeting; D005909:Glioblastoma / Q000235:genetics* / Q000532:radiotherapy; D006801:Humans; D035683:MicroRNAs; D034622:RNA Interference; D020871:RNA Stability; D034741:RNA, Small Interfering; D011839:Radiation, Ionizing; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*
chemical_list: D020413:3' Untranslated Regions; D004268:DNA-Binding Proteins; D035683:MicroRNAs; D034741:RNA, Small Interfering; D011838:Radiation-Sensitizing Agents; C113187:XRCC2 protein, human; C101467:XRCC4 protein, human