Comparison of cellular lethality in DNA repair-proficient or -deficient cell lines resulting from exposure to 70 MeV/n protons or 290 MeV/n carbon ions

Genet, Stefan C.; Maeda, Jun; Fujisawa, Hiroshi; Yurkon, Charles R.; Fujii, Yukihiko; Romero, Ashley; Genik, Paula C.; Fujimori, A.; Kitamura, Hisashi; Kato, Takamitsu A.

doi:10.3892/or.2012.1982

Cited by 16 publications

(22 citation statements)

References 31 publications

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“…Thus, these highly clustered foci represent a hall mark of high LET radiation. The presence of larger and persistent γH2AX foci after high LET damage and the dependency on NHEJ for repair has been reported previously, although detailed analysis of their complexity has not been hitherto described [5], [18], [19], [21], [33], [34], [35]. Perhaps surprisingly, we also observed some foci clustering following exposure to X-rays although such clustered foci were much smaller, less complex and distinct in nature to that observed after high LET irradiation.…”

Section: Discussionsupporting

confidence: 79%

Visualisation of γH2AX Foci Caused by Heavy Ion Particle Traversal; Distinction between Core Track versus Non-Track Damage

et al. 2013

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Heavy particle irradiation produces complex DNA double strand breaks (DSBs) which can arise from primary ionisation events within the particle trajectory. Additionally, secondary electrons, termed delta-electrons, which have a range of distributions can create low linear energy transfer (LET) damage within but also distant from the track. DNA damage by delta-electrons distant from the track has not previously been carefully characterised. Using imaging with deconvolution, we show that at 8 hours after exposure to Fe (∼200 keV/µm) ions, γH2AX foci forming at DSBs within the particle track are large and encompass multiple smaller and closely localised foci, which we designate as clustered γH2AX foci. These foci are repaired with slow kinetics by DNA non-homologous end-joining (NHEJ) in G1 phase with the magnitude of complexity diminishing with time. These clustered foci (containing 10 or more individual foci) represent a signature of DSBs caused by high LET heavy particle radiation. We also identified simple γH2AX foci distant from the track, which resemble those arising after X-ray exposure, which we attribute to low LET delta-electron induced DSBs. They are rapidly repaired by NHEJ. Clustered γH2AX foci induced by heavy particle radiation cause prolonged checkpoint arrest compared to simple γH2AX foci following X-irradiation. 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.

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Section: Discussionsupporting

confidence: 79%

Visualisation of γH2AX Foci Caused by Heavy Ion Particle Traversal; Distinction between Core Track versus Non-Track Damage

et al. 2013

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“…In the present study, the biological effect of irradiation with the SOBP beam region of C ions was assessed using the OptiCell™ culture system, as reported previously (10,11), and used to construct a three-dimensional geometric in vitro experiment. The results of the present study demonstrated that a 6 cm wide SOBP C beam consists of various monoenergetic Bragg peak beams, which cause rapid build-up of radiation dosage at a depth of 8 cm, a gradual decrease until the proximal boundary and a rapid decrease at 14 cm.…”

Section: Discussionmentioning

confidence: 99%

“…The cell survival assay using OptiCell culture chambers was performed as described previously (10,11). For the OptiCell survival assay following irradiation with SOBP C ions, 10 ml of culture medium containing between 400 and 600 cells was added to each chamber ~3 h prior to irradiation.…”

Section: Methodsmentioning

confidence: 99%

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Investigation of the relative biological effectiveness and uniform isobiological killing effects of irradiation with a clinical carbon SOBP beam on DNA repair deficient CHO cells

Sunada¹,

Cartwright²,

Hirakawa³

et al. 2017

Oncology Letters

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Abstract. Spread-out Bragg peak (SOBP) C ions have been used clinically in charged particle radiation therapy for years. An SOBP beam consists of various monoenergetic Bragg peaks; however, the biological effect of irradiation with an SOBP beam track has not been well-studied. In order to determine the clinically prospective molecular targets, radiosensitivity to the beam track in DNA repair deficient cell lines was investigated. A total of four distinct Chinese hamster ovary (CHO) cell lines, including CHO10B2 (wild-type), V3 (protein kinase DNA-activated catalytic polypeptide deficient), 51D1 (RAD51 paralog D deficient) and PADR9 [poly(ADP-ribose) polymerase (PARP) deficient], were irradiated with gamma-rays, C ions (290 MeV/n) and Fe ions (500 MeV/n), in order to compare cellular lethality. An OptiCell™ culture system was used to evaluate the lethality at distinct depths of SOBP C ions. Relative biological effectiveness (RBE) values of C ions (linear energy transfer (LET), 13 and 70 keV/µm) and Fe ions (LET, 200 keV/µm) were calculated from cell survival using colony formation assay with standard cell dishes. All cell lines exhibited similar sensitivity to 70 keV/µm C ions and 200 keV/ µm Fe ions. Furthermore, V3 cells did not exhibit increased sensitivity to high LET C ions and Fe ions, compared with low LET gamma-rays and C ions, and 51D1 cells irradiated with 13 keV/µm C ions exhibited relatively high RBE values among the tested cell lines. Conversely, PADR9 cells exhibited low RBE values for 13 keV/µm C ions and high RBE values for 70 keV/µm C ions. Obtained using the OptiCell system, the survival fractions in the SOBP region were uniform for wild-type and PADR9 cells. Conversely, V3 and 51D1 cells exhibited decreased cell death in the distal region of the SOBP. These results indicated that PARP is a more effective target for clinical beam therapy, compared with the non-homologous end joining repair and homologous recombination repair pathways. PARP deficiency may be an optimal target for C ion therapy and the results of the present study may contribute to the development of a more effective heavy ion radiation therapy. IntroductionHeavy ion radiation therapy began in the 1970s in the USA as a more efficient radiation therapy compared with classical X-ray therapy (1,2). Heavy ion therapy is gaining prevalence, and has been increasingly utilized in Japan, China, Germany and Italy (1,2). Heavy ions exhibit three advantageous cancer cell killing characteristics when compared with X-rays. Heavy ions exhibit a more efficient dose distribution in cancer tissues due to the Bragg peak. The phenomenon allows for the majority of the dose to be deposited within the cancer tissues, avoiding unnecessary radiation exposure to normal tissues. In addition, heavy ions form complex DNA lesions within the cell due to the large amount of energy deposited during particle/DNA interactions. Heavy ions are able to produce more complex DNA lesions compared with X-rays and gamma-rays (1,2). Complex DNA damage lesions are more diff...

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“…A review of the literature suggests a trend for a higher proton RBE in x-ray–resistant versus x-ray–sensitive cells [20–23]. However, in studies using wild-type and DNA-PKcs–deficient or DNA-PKcs–inhibited cells (or other key constituents of NHEJ), a significant proton RBE difference between sensitive and resistant cells has generally not been observed [15, 16, 24, 25]. …”

Section: Introductionmentioning

confidence: 99%

The Relative Biological Effect of Spread-Out Bragg Peak Protons in Sensitive and Resistant Tumor Cells

Lin

Chen

et al. 2017

International Journal of Particle Therapy

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Purpose Variations in the radiosensitivity of tumor cells within and between tumors impact tumor response to radiation, including the dose required to achieve permanent local tumor control. The increased expression of DNA-PKcs, a key component of a major DNA damage repair pathway in tumors treated by radiation, suggests that DNA-PKcs–dependent repair is likely a cause of tumor cell radioresistance. This study evaluates the relative biological effect of spread-out Bragg-peak protons in DNA-PKcs–deficient cells and the same cells transfected with a functional DNA-PKcs gene. Materials and Methods A cloned radiation-sensitive DNA-PKcs–deficient tumor line and its DNA-PKcs–transfected resistant counterpart were used in this study. The presence of functional DNA-PKcs was evaluated by DNA-PKcs autophosphorylation. Cells to be proton irradiated or x-irradiated were obtained from the same single cell suspension and dilution series to maximize precision. Cells were concurrently exposed to 6-MV x-rays or mid 137-MeV spread-out Bragg peak protons and cultured for colony formation. Results The surviving fraction data were well fit by the linear-quadratic model for each of 8 survival curves. The results suggest that the relative biological effectiveness of mid spread-out Bragg peak protons is approximately 6% higher in DNA-PKcs–mediated resistant tumor cells than in their DNA-PKcs–deficient and radiation-sensitive counterpart. Conclusion DNA-PKcs–dependent repair of radiation damage is less capable of repairing mid spread-out Bragg peak proton lesions than photon-induced lesions, suggesting protons may be more efficient at sterilizing DNA-PKcs–expressing cells that are enriched in tumors treated by conventional fractionated dose x-irradiation.

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Comparison of cellular lethality in DNA repair-proficient or -deficient cell lines resulting from exposure to 70 MeV/n protons or 290 MeV/n carbon ions

Cited by 16 publications

References 31 publications

Visualisation of γH2AX Foci Caused by Heavy Ion Particle Traversal; Distinction between Core Track versus Non-Track Damage

Visualisation of γH2AX Foci Caused by Heavy Ion Particle Traversal; Distinction between Core Track versus Non-Track Damage

Investigation of the relative biological effectiveness and uniform isobiological killing effects of irradiation with a clinical carbon SOBP beam on DNA repair deficient CHO cells

The Relative Biological Effect of Spread-Out Bragg Peak Protons in Sensitive and Resistant Tumor Cells

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