2002 Fiscal Year Final Research Report Summary
Inhibition of DNA-PK activity by phosphorothioate oligonucleotides
| Project/Area Number |
12470184
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Radiation science
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| Research Institution | The University of Tokyo |
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Principal Investigator |
HOSOI Yoshio Graduate School of Medcine, The University of Tokyo, Associate Professor, 大学院・医学系研究科, 助教授 (50238747)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUMOTO Yoshihisa Graduate Schod of Medicine, The University of Tokyo, Research associate, 大学院・医学系研究科, 助手 (20302672)
SUZUKI Norio Graduate School of Medcine, The University of Tokyo, Professor, 大学院・医学系研究科, 教授 (10010050)
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| Project Period (FY) |
2000 – 2002
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| Keywords | Ionizing radiation / DNA repair / Cancer |
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| Research Abstract |
Phosphorothioate oligonudeotides and suramin bind to heparin binding proteins including DNA polymerases, and inhibit their functions. In the present study, we report inhibition of DNA-dependent protein kinase (DNA-PK) activity by phosphorothioate oiigonucleotides, suramin and heparin. Inhibitory effect of phosphorothioate oligonudeotides on DNA-PK activity was increased with length and reached a plateau at 36-mer. The base composition of phosphorothioate digonucleotides did not affect the inhibitory effect The inhibitory effect by phosphorothioate oligodeoxycytidine 36-mer can be about 200-fold greater than that by the phosphodiester oligodeoxycytidine 36-mer. The inhibitory effect was also observed with purified DNA-PK, which suggests direct interaction between DNA-PK and phosphorothioate oligonucleotides. DNA-PK will have different binding positions for double-stranded DNA and phosphorothioate oligodeoxycytidine 36-mer because they were not competitive in DNA-PK activation. Suramin and heparin inhibited DNA-PK activity with IC_<50> of 1.7 μM and 0.27 μg/ml respectively. DNA-PK activities and DNA double-stranded breaks (DSBs) repair in cultured cells were significantly suppressed by the treatment with suramin in vivo. Our present observations suggest that suramin mav possibly result in sensitization of cells to ionizing radiation bv inactivation of DNA-PK and the impairment of DSBs repair.
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