Ryuichi Okayasu

Summary

Affiliation: National Institute of Radiological Sciences
Country: Japan

Publications

  1. pmc DNA double-strand break induction in Ku80-deficient CHO cells following boron neutron capture reaction
    Yuko Kinashi
    Research Reactor Institute, Kyoto University, Sennan gun, Osaka, Japan
    Radiat Oncol 6:106. 2011
  2. ncbi request reprint Induction of DNA double strand breaks by arsenite: comparative studies with DNA breaks induced by X-rays
    Ryuichi Okayasu
    International Space Radiation Laboratory and Environmental Toxicological Research Group, National Institute of Radiological Sciences, 4 9 1 Anagawa, Inage Ku, Chiba 263 8555, Japan
    DNA Repair (Amst) 2:309-14. 2003
  3. ncbi request reprint Radiosensitization of normal human cells by LY294002: cell killing and the rejoining of DNA and interphase chromosome breaks
    Ryuichi Okayasu
    International Space Radiation Laboratory, National Institute of Radiological Sciences, Inage Ku, Chiba, Japan
    J Radiat Res 44:329-33. 2003
  4. doi request reprint Repair of DNA damage induced by accelerated heavy ions--a mini review
    Ryuichi Okayasu
    International Open Laboratory and Heavy ion Radiobiology Research Group, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Inage Ku, Chiba, Japan
    Int J Cancer 130:991-1000. 2012
  5. ncbi request reprint Repair of DNA damage induced by accelerated heavy ions in mammalian cells proficient and deficient in the non-homologous end-joining pathway
    Ryuichi Okayasu
    International Space Radiation Laboratory, National Institute of Radiological Sciences, Inage Ku, Chiba shi 263 8555, Japan
    Radiat Res 165:59-67. 2006
  6. doi request reprint Influence of track directions on the biological consequences in cells irradiated with high LET heavy ions
    Yoshihiro Fujii
    Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Inage, Chiba, Japan
    Int J Radiat Biol 89:401-10. 2013
  7. doi request reprint Sulforaphane induces DNA double strand breaks predominantly repaired by homologous recombination pathway in human cancer cells
    Emiko Sekine-Suzuki
    Heavy Ion Radiobiology Research Group, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4 9 1 Anagawa, Inage Ku, Chiba 263 8555, Japan
    Biochem Biophys Res Commun 377:341-5. 2008
  8. doi request reprint High LET heavy ion radiation induces lower numbers of initial chromosome breaks with minimal repair than low LET radiation in normal human cells
    Emiko Sekine
    Heavy Ion Radiobiology Research Group, National Institute of Radiological Sciences, 4 9 1 Anagawa, Inage Ku, Chiba shi 263 8555, Japan
    Mutat Res 652:95-101. 2008
  9. doi request reprint Rejoining kinetics of G1-PCC breaks induced by different heavy-ion beams with a similar LET value
    Chizuru Tsuruoka
    Heavy Ion Radiobiology Research Group, National Institute of Radiological Sciences, 4 9 1 Anagawa, Chiba 263 8555, Japan
    Mutat Res 701:47-51. 2010
  10. doi request reprint The difference in LET and ion species dependence for induction of initially measured and non-rejoined chromatin breaks in normal human fibroblasts
    Chizuru Tsuruoka
    Heavy Ion Radiobiology Research Group, National Institute of Radiological Sciences, 4 9 1 Anagawa, Chiba, Japan
    Radiat Res 170:163-71. 2008

Collaborators

Detail Information

Publications35

  1. pmc DNA double-strand break induction in Ku80-deficient CHO cells following boron neutron capture reaction
    Yuko Kinashi
    Research Reactor Institute, Kyoto University, Sennan gun, Osaka, Japan
    Radiat Oncol 6:106. 2011
    ..The purpose of this study is to verify that BNCR will increase cell killing and slow disappearance of repair protein-related foci to a greater extent in DNA repair-deficient cells than in wild-type cells...
  2. ncbi request reprint Induction of DNA double strand breaks by arsenite: comparative studies with DNA breaks induced by X-rays
    Ryuichi Okayasu
    International Space Radiation Laboratory and Environmental Toxicological Research Group, National Institute of Radiological Sciences, 4 9 1 Anagawa, Inage Ku, Chiba 263 8555, Japan
    DNA Repair (Amst) 2:309-14. 2003
    ..Based on these data, further mechanistic investigations including the involvement of DNA-DSB repair proteins are warranted in the recovery process from arsenic (As) exposure...
  3. ncbi request reprint Radiosensitization of normal human cells by LY294002: cell killing and the rejoining of DNA and interphase chromosome breaks
    Ryuichi Okayasu
    International Space Radiation Laboratory, National Institute of Radiological Sciences, Inage Ku, Chiba, Japan
    J Radiat Res 44:329-33. 2003
    ..These results suggest that the inhibition of DSB repair mediated the radiosensitizing effect of LY294002 at the dose level that we used...
  4. doi request reprint Repair of DNA damage induced by accelerated heavy ions--a mini review
    Ryuichi Okayasu
    International Open Laboratory and Heavy ion Radiobiology Research Group, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Inage Ku, Chiba, Japan
    Int J Cancer 130:991-1000. 2012
    ..Accelerated heavy ions have become valuable tools to investigate the molecular mechanisms underlying repair of DNA DSBs, the most crucial form of DNA damage induced by radiation and various chemotherapeutic agents...
  5. ncbi request reprint Repair of DNA damage induced by accelerated heavy ions in mammalian cells proficient and deficient in the non-homologous end-joining pathway
    Ryuichi Okayasu
    International Space Radiation Laboratory, National Institute of Radiological Sciences, Inage Ku, Chiba shi 263 8555, Japan
    Radiat Res 165:59-67. 2006
    ..This delay was further emphasized in NHEJ-defective 180BR cells. Our results indicate that high-LET radiation induces complex DNA damage that is not easily repaired or is not repaired by NHEJ even at low radiation doses such as 2 Gy...
  6. doi request reprint Influence of track directions on the biological consequences in cells irradiated with high LET heavy ions
    Yoshihiro Fujii
    Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Inage, Chiba, Japan
    Int J Radiat Biol 89:401-10. 2013
    ..The impact of the damage distribution to cellular survival and chromosomal aberrations following high Linear Energy Transfer (LET) radiation was investigated...
  7. doi request reprint Sulforaphane induces DNA double strand breaks predominantly repaired by homologous recombination pathway in human cancer cells
    Emiko Sekine-Suzuki
    Heavy Ion Radiobiology Research Group, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4 9 1 Anagawa, Inage Ku, Chiba 263 8555, Japan
    Biochem Biophys Res Commun 377:341-5. 2008
    ..G2/M arrest by SFN, a typical response for cells exposed to ionizing radiation was also observed. Our new data indicate the clear induction of DSBs by SFN and a useful anti-tumor aspect of SFN through the induction of DNA DSBs...
  8. doi request reprint High LET heavy ion radiation induces lower numbers of initial chromosome breaks with minimal repair than low LET radiation in normal human cells
    Emiko Sekine
    Heavy Ion Radiobiology Research Group, National Institute of Radiological Sciences, 4 9 1 Anagawa, Inage Ku, Chiba shi 263 8555, Japan
    Mutat Res 652:95-101. 2008
    ..These results at the chromosome level substantiate and extend the notion that high LET radiation produces complex-type DNA double strand breaks (DSBs)...
  9. doi request reprint Rejoining kinetics of G1-PCC breaks induced by different heavy-ion beams with a similar LET value
    Chizuru Tsuruoka
    Heavy Ion Radiobiology Research Group, National Institute of Radiological Sciences, 4 9 1 Anagawa, Chiba 263 8555, Japan
    Mutat Res 701:47-51. 2010
    ....
  10. doi request reprint The difference in LET and ion species dependence for induction of initially measured and non-rejoined chromatin breaks in normal human fibroblasts
    Chizuru Tsuruoka
    Heavy Ion Radiobiology Research Group, National Institute of Radiological Sciences, 4 9 1 Anagawa, Chiba, Japan
    Radiat Res 170:163-71. 2008
    ..This suggests that the LET-dependent structure in the biological effects is reflected in biological consequences of repair processes...
  11. doi request reprint Down regulation of BRCA2 causes radio-sensitization of human tumor cells in vitro and in vivo
    Dong Yu
    Heavy Ion Radiobiology Research Group, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4 9 1 Anagawa, Inage Ku, Chiba shi, 263 8555, Japan
    Cancer Sci 99:810-5. 2008
    ....
  12. doi request reprint Chemopreventive agent sulforaphane enhances radiosensitivity in human tumor cells
    Dong Yu
    Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Inage Ku, Chiba shi, Japan
    Int J Cancer 125:1205-11. 2009
    ..To the best of our knowledge, our study is the first report showing SFN-enhanced radiosensitivity of tumor cells in vitro and in vivo, which opens the door for a multitude of clinical applications for chemoradiotherapy using SFN...
  13. ncbi request reprint Inhibition of DNA-double strand break repair by antimony compounds
    Sentaro Takahashi
    Environmental and Toxicological Research Group, National Institute of Radiological Sciences, 4 9 1 Anagawa, Inage Ku, 263 8555, Chiba, Japan
    Toxicology 180:249-56. 2002
    ..This is the first report to indicate that antimony compounds may inhibit the repair of radiation-induced DNA DSB...
  14. doi request reprint ASPM influences DNA double-strand break repair and represents a potential target for radiotherapy
    Takamitsu A Kato
    Heavy Ion Radiobiology Research Group, Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4 9 1 Anagawa, Inage Ku, Chiba shi, Chiba, Japan
    Int J Radiat Biol 87:1189-95. 2011
    ..The roles of ASPM on radiosensitivity, however, have never been studied...
  15. pmc In vitro characterization of cells derived from chordoma cell line U-CH1 following treatment with X-rays, heavy ions and chemotherapeutic drugs
    Takamitsu A Kato
    Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4 9 1 Anagawa, Inage Ku, Chiba shi, 263 8555 Japan
    Radiat Oncol 6:116. 2011
    ..In order to overcome this situation, we successfully derived a cell line with a shorter doubling time from the first validated chordoma line U-CH1 and obtained invaluable cell biological data...
  16. doi request reprint Effectiveness of combined treatment using X-rays and a phosphoinositide 3-kinase inhibitor, ZSTK474, on proliferation of HeLa cells in vitro and in vivo
    Kazunori Anzai
    Heavy Ion Radiobiology Research Group, National Institute of Radiological Sciences, Chiba, Japan
    Cancer Sci 102:1176-80. 2011
    ..Combined treatment with X-rays and ZSTK474 has greater therapeutic potential than radiation or drug therapy alone, both in vitro and in vivo...
  17. ncbi request reprint The PCC assay can be used to predict radiosensitivity in biopsy cultures irradiated with different types of radiation
    Masao Suzuki
    Heavy Ion Radiobiology Research Group, National Institute of Radiological Sciences, Chiba 263, Japan
    Oncol Rep 16:1293-9. 2006
    ....
  18. doi request reprint Ascorbic acid gives different protective effects in human cells exposed to X-rays and heavy ions
    Yoshihiro Fujii
    Research Center for Charged Particle Therapy, Heavy Ion Radiobiology Research Group, National Institute of Radiological Sciences, Inage Ku, Chiba shi, Japan
    Mutat Res 699:58-61. 2010
    ..These findings provide new insight into the mechanism of DNA damage and repair produced by heavy ion irradiation...
  19. ncbi request reprint Inhibition of homologous recombination repair in irradiated tumor cells pretreated with Hsp90 inhibitor 17-allylamino-17-demethoxygeldanamycin
    Miho Noguchi
    Graduate School of Science and Technology, Chiba University, Inage Ku, Chiba 263 8522, Japan
    Biochem Biophys Res Commun 351:658-63. 2006
    ..Our data demonstrate for the first time that 17-AAG inhibits the HR repair process and could provide a new therapeutic strategy to selectively result in higher tumor cell killing...
  20. doi request reprint Contributions of direct and indirect actions in cell killing by high-LET radiations
    Ryoichi Hirayama
    Heavy Ion Radiobiology Research Group, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4 9 1 Anagawa, Inage Ku, Chiba 263 8555, Japan
    Radiat Res 171:212-8. 2009
    ..However, the peak value was much higher for RBE(D) (5.99) than RBE(I) (1.89). Thus direct action contributes more to the high RBE of high-LET radiations than indirect action does...
  21. doi request reprint Effects of carbon ion beam on putative colon cancer stem cells and its comparison with X-rays
    Xing Cui
    Heavy Ion Radiobiology Research Group, Research Center for Radiation Emergency Medicine, National Institute of Radiological Sciences NIRS, Chiba, Japan
    Cancer Res 71:3676-87. 2011
    ..Taken together, carbon ion beam therapy may have an advantage over photon beam therapy by improved targeting of putative colon cancer stem-like cells...
  22. doi request reprint Ionizing radiation downregulates ASPM, a gene responsible for microcephaly in humans
    Akira Fujimori
    Cellular and Molecular Biology Team, National Institute of Radiological Sciences, Heavy Ion Radiobiology Research Group, Research Center for Charged Particle Therapy, 4 9 1 Anagawa, Inage, Chiba 263 8555, Japan
    Biochem Biophys Res Commun 369:953-7. 2008
    ..A similar suppression was observed in the irradiated neurosphere cultures. This is the first report suggesting that the suppression of Aspm by IR could be the initial molecular target leading to the future microcephaly formation...
  23. ncbi request reprint Caffeine sensitizes nondividing human fibroblasts to x rays by inducing a high frequency of misrepair
    Tetsuya Kawata
    Department of Radiology, Graduate School of Medicine, Chiba, Japan
    Radiat Res 164:509-13. 2005
    ..Since most DNA repair in nongrowing G0 cells is believed to result from nonhomologous end joining (NHEJ), caffeine may influence the fidelity of the NHEJ pathway in irradiated G0 cells...
  24. doi request reprint Arsenic accumulation, elimination, and interaction with copper, zinc and manganese in liver and kidney of rats
    Xing Cui
    Environmental Health Sciences Division, National Institute for Environmental Studies, Ibaraki 305 8506, Japan
    Food Chem Toxicol 46:3646-50. 2008
    ..These data indicate that arsenic is widely distributed and significantly accumulated in various organs and influences on other trace elements, and also modulates MT-1 expression in the liver and kidney...
  25. ncbi request reprint Metabolism and the paradoxical effects of arsenic: carcinogenesis and anticancer
    Xing Cui
    Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Chiba 263 8555, Japan
    Curr Med Chem 15:2293-304. 2008
    ..We also summarize the clinical use of arsenic trioxide (As2O3) to date and discuss new therapeutic strategies such as concurrent arsenic-radiation therapy to achieve local tumor control and enhance the radiosensitivity of solid tumors...
  26. pmc Visualisation of γH2AX Foci Caused by Heavy Ion Particle Traversal; Distinction between Core Track versus Non-Track Damage
    Nakako Izumi Nakajima
    Research Center for Charged Particle Therapy and International Open Laboratory, National Institute of Radiological Sciences, Chiba, Japan
    PLoS ONE 8:e70107. 2013
    ..However, mitotic entry was observed when ∼10 clustered foci remain. Thus, cells can progress into mitosis with multiple clusters of DSBs following the traversal of a heavy particle. ..
  27. ncbi request reprint Extremely low dose ionizing radiation up-regulates CXC chemokines in normal human fibroblasts
    Akira Fujimori
    Environmental and Toxicological Sciences Research Group, Research Center for Radiation Safety, National Institute of Radiological Sciences, 4 9 1 Anagawa, Inage, Chiba, Japan
    Cancer Res 65:10159-63. 2005
    ..In addition, our comprehensive approach using a novel expression profiling method is a powerful strategy to explore biological functions associated with very low levels of toxic agents...
  28. ncbi request reprint Facilitated detection of chromosome break and repair at low levels of ionizing radiation by addition of wortmannin to G1-type PCC fusion incubation
    Maki Okada
    International Space Radiation Laboratory, Research Center for Radiation Safety, National Institute of Radiological Sciences, 4 9 1 Anagawa, Inage Ku, Chiba 263 8555, Japan
    Mutat Res 562:11-7. 2004
    ..Our chromosome repair assay is useful for evaluating the accuracy of other assays measuring DNA DSB repair at doses equal or less than 0.5 Gy of ionizing radiation...
  29. ncbi request reprint Cytotoxicity of cigarette smoke condensate is not due to DNA double strand breaks: Comparative studies using radiosensitive mutant and wild-type CHO cells
    Takamitsu Kato
    Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, USA
    Int J Radiat Biol 83:583-91. 2007
    ....
  30. pmc Roles of the major, small, acid-soluble spore proteins and spore-specific and universal DNA repair mechanisms in resistance of Bacillus subtilis spores to ionizing radiation from X rays and high-energy charged-particle bombardment
    Ralf Moeller
    German Aerospace Center, Institute of Aerospace Medicine, Radiation Biology Division, Department of Photo and Exobiology, Cologne, Germany
    J Bacteriol 190:1134-40. 2008
    ....
  31. doi request reprint Comparison of the induction and disappearance of DNA double strand breaks and gamma-H2AX foci after irradiation of chromosomes in G1-phase or in condensed metaphase cells
    Takamitsu A Kato
    Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, United States
    Mutat Res 639:108-12. 2008
    ..On the other hand, no difference was seen for the gel electrophoresis assay. Our data may suggest the limited accessibility of dephosphorylation enzyme in irradiated metaphase cells or trapped gamma-H2AX in condensed chromatin...
  32. ncbi request reprint Radio-sensitivity of the cells from amyotrophic lateral sclerosis model mice transfected with human mutant SOD1
    Reika Wate
    Department of Neurology, Kansai Medical University, Moriguchi, Japan
    J Radiat Res 46:67-73. 2005
    ....
  33. ncbi request reprint Enhancement of chromosomal aberrations in tumor cells with a non-labeled Cu-PTSM and irradiation with Cu K-shell monochromatic X rays
    Kaoru Takakura
    Physics Department, Division of Natural Sciences, International Christian University, Mitaka shi, Tokyo 181 8585, Japan
    Radiat Prot Dosimetry 122:188-94. 2006
    ..In this study, uniqueness in physical property such as Cu atom K-shell ionisation was applied for the enhancement of biological effects in cancer cells...
  34. ncbi request reprint DNA topoisomerase inhibitor, etoposide, enhances GC-box-dependent promoter activity via Sp1 phosphorylation
    Ichiro Niina
    Department of Molecular Biology, School of Medicine, University of Occupational and Environmental Health, Iseigaoka, Fukuoka, Japan
    Cancer Sci 98:858-63. 2007
    ..Taken together, these findings demonstrate a novel genomic response to anticancer agents that induce Sp1 phosphorylation, and might contribute to tumor progression and drug resistance...
  35. ncbi request reprint Silencing expression of the catalytic subunit of DNA-dependent protein kinase by small interfering RNA sensitizes human cells for radiation-induced chromosome damage, cell killing, and mutation
    Yuanlin Peng
    Department of Environmental and Radiological Health Sciences, Colorado State University Fort Collins, Colorado 80523 1681, USA
    Cancer Res 62:6400-4. 2002
    ....