siRNA Targeting NBS1 or XIAP Increases Radiation Sensitivity of Human Cancer Cells Independent of TP53 Status (original) (raw)
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1 September 2006 siRNA Targeting NBS1 or XIAP Increases Radiation Sensitivity of Human Cancer Cells Independent of TP53 Status
Ken Ohnishi,Zorica Scuric,Robert H. Schiestl,Noritomo Okamoto,Akihisa Takahashi,Takeo Ohnishi
Author Affiliations +
Ken Ohnishi,1 Zorica Scuric,2 Robert H. Schiestl,2 Noritomo Okamoto,3 Akihisa Takahashi,1 Takeo Ohnishi1,*
1aDepartment of Biology, Nara Medical University School of Medicine, 840 Shijo-cho, Kashihara, Nara 6
2cDepartments of Pathology, Environmental Health and Radiation Oncology, Geffen School of Medicine an
3bDepartment of Otorhinolaryngology, Nara Medical University School of Medicine, 840 Shijo-cho, Kashi
*Address for correspondence: Department of Biology, Nara Medical University School of Medicine, Kashihara, Nara 634-8521, Japan; tohnishi@naramed-u.ac.jp
Abstract
Ohnishi, K., Scuric, Z., Schiestl, R. H., Okamoto, N., Takahashi, A. and Ohnishi, T. siRNA Targeting NBS1 or XIAP Increases Radiation Sensitivity of Human Cancer Cells Independent of TP53 Status. Radiat. Res. 166, 454–462 (2006).
NBS1 is essential for the repair of radiation-induced DNA double-strand breaks (DSBs) in yeast and higher vertebrate cells. In this study, we examined whether suppressed NBS1 expression by small interference RNA (siRNA) could enhance radiation sensitivity in cancer cells with different TP53 status. We used human non-small cell lung cancer cells differing in TP53 gene status (H1299/wt_p53_ cells bearing wild-type TP53 or H1299/m_p53_ cells bearing mutant TP53). A DNA cassette expressing siRNA targeted for the NBS1 gene was transfected into those cell lines, and radiation sensitivity was examined with a colony-forming assay. Cellular levels of NBS1 and other proteins were analyzed using Western blotting. We found that the radiation sensitivity of H1299/wt_p53_ and H1299/m_p53_ cells was enhanced by transfection of the DNA cassette. In the _NBS1_-siRNA-transfected cells, we observed decreased constitutive expression of NBS1 protein and decreased radiation-induced accumulation of phosphorylated NBS1 protein. In addition, radiation-induced expression of the transcription factor NF-κB (NFKB) and XIAP (X-chromosome-linked inhibitor of apoptosis protein) was suppressed by _NBS1_-siRNA. Enhanced X-ray sensitivity after _NBS1_-siRNA transfection was achieved in TP53 wild-type cells and sensitivity was even more pronounced in TP53 mutant cells. The transfection of siRNA targeted for XIAP also enhanced X-ray sensitivity even more for TP53 mutant cells compared to TP53 wild-type cells. Our data suggest that the sensitization to radiation results from _NBS1_-siRNA-mediated suppression of DNA repair and/ or X-ray-induced cell survival signaling pathways through NFKB and XIAP. siRNA targeting appears to be a novel radiation-sensitizing agent, particularly in human TP53 mutant cancer cells.
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Ken Ohnishi, Zorica Scuric, Robert H. Schiestl, Noritomo Okamoto, Akihisa Takahashi, and Takeo Ohnishi "siRNA Targeting NBS1 or XIAP Increases Radiation Sensitivity of Human Cancer Cells Independent of TP53 Status," Radiation Research 166(3), 454-462, (1 September 2006). https://doi.org/10.1667/RR3606.1
Received: 7 February 2006; Accepted: 1 May 2006; Published: 1 September 2006
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