| 1. |
- Acheva, Anna, et al.
(författare)
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Presence of Stromal Cells Enhances Epithelial-to-Mesenchymal Transition (EMT) Induction in Lung Bronchial Epithelium after Protracted Exposure to Oxidative Stress of Gamma Radiation
- 2019
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Ingår i: Oxidative Medicine and Cellular Longevity. - : Hindawi Limited. - 1942-0900 .- 1942-0994. ; 2019
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to investigate the role of a microenvironment in the induction of epithelial-to-mesenchymal transition (EMT) as a sign of early stages of carcinogenesis in human lung epithelial cell lines after protracted low-dose rate gamma-radiation exposures. BEAS-2B and HBEC-3KT lung cell lines were irradiated with low-dose rate gamma-rays (Cs-137, 1.4 or 14 mGy/h) to 0.1 or 1 Gy with or without adding TGF-beta. TGF-beta-treated samples were applied as positive EMT controls and tested in parallel to find out if the radiation has a potentiating effect on the EMT induction. To evaluate the effect of the stromal component, the epithelial cells were irradiated in cocultures with stromal MRC-9 lung fibroblasts. On day 3 post treatment, the EMT markers: alpha-SMA, vimentin, fibronectin, and E-cadherin, were analyzed. The oxidative stress levels were evaluated by 8-oxo-dG analysis in both epithelial and fibroblast cells. The protracted exposure to low Linear Energy Transfer (LET) radiation at the total absorbed dose of 1 Gy was able to induce changes suggestive of EMT. The results show that the presence of the stromal component and its signaling (TGF-beta) in the cocultures enhances the EMT. Radiation had a minor cumulative effect on the TGF-beta-induced EMT with both doses. The oxidative stress levels were higher than the background in both epithelial and stromal cells post chronic irradiation (0.1 and 1 Gy); as for the BEAS-2B cell line, the increase was statistically significant. We suggest that the induction of EMT in bronchial epithelial cells by radiation requires more than single acute exposure and the presence of stromal component might enhance the effect through free radical production and accumulation.
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| 2. |
- Cheng, Lei, et al.
(författare)
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Comet assay reveals an interaction of DNA lesions and impairment of DNA repair in peripheral blood lymphocytes simultaneously exposed to alpha particles and X-rays
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The biological effectiveness of ionising radiation is related to the ionisation density which is defined by the linear energy transfer LET. Radiation quality factors are applied to calculate the equivalent dose in the field of radiation protection and the biologically effective dose in the field of radiotherapy. Additivity is assumed in exposure scenarios where radiations of different qualities are mixed. We have carried out a series of studies on the cytogenetic effect of exposing human peripheral blood lymphocytes to a mixed beam of the high LET alpha radiation and low LET X-rays and could demonstrate that both radiations interact in producing more chromosomal aberrations than expected based on additivity. The aim of the present investigation was to look at the mechanism of the interaction, especially with respect to the question if it is due to an augmented level of initial damage or impaired DNA repair. The level of DNA damage and the kinetics of damage repair was quantified by the alkaline comet assay. The levels of phosphorylated, key DNA damage response (DDR) proteins were also measured by Western blotting. The results revealed that alpha particles and X-rays interact in inducing DNA damage above the level predicted by assuming additivity and that the repair of damage occurs with a delay. Moreover, the activation levels of the key DDR proteins ATM, p53 and DNA PK were highest in cells exposed to mixed beams substantiating the idea exposure to mixed beams presents a challenge to the cellular DNA damage response system.
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| 3. |
- Cheng, Lei, et al.
(författare)
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Modulation of radiation-induced cytogenetic damage in human peripheral blood lymphocytes by hypothermia
- 2015
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Ingår i: Mutation research. Genetic toxicology and environmental mutagenesis. - : Elsevier BV. - 1383-5718 .- 1879-3592. ; 793:SI, s. 96-100
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Recent studies have shown that low temperature (hypothermia) at exposure can act in a radioprotective manner at the level of cytogenetic damage. The mechanisms of this phenomenon are not understood, but it was suggested to be due to hypothermia-induced perturbations of the cell cycle. The purpose of the present study was to detect whether a reduced frequency of micronuclei is observed in peripheral blood lymphocytes (PBL) irradiated at low temperature and harvested sequentially at 3 time points. Additionally, the level of apoptosis was estimated by microscopic analysis of the MN slides. Materials and methods: Experiments were carried out with blood drawn from three donors at the Stockholm University and from three donors at the Jan Kochanowski University. Prior to irradiation, blood samples were incubated for 20 mm and irradiated at the respective temperature (0 degrees C and 37 degrees C) with gamma rays. Whole blood cultures were set up, cytochalasin B was added after 44h of irradiation and the samples were harvested after 72,96 and 120 h of incubation time. Results and conclusions: The frequency of micronuclei was markedly lower in PBL harvested at 72h, 96 h and 120 h following irradiation at 0 degrees C as compared to 37 degrees C. This indicates that the temperature effect observed in peripheral blood lymphocytes after irradiation is not related to a temporary perturbation of the cell cycle. Also, it is not due to selective elimination of damaged cells by apoptosis.
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| 4. |
- Cheng, Lei, et al.
(författare)
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Simultaneous induction of dispersed and clustered DNA lesions compromises DNA damage response in human peripheral blood lymphocytes
- 2018
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 13:10
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Tidskriftsartikel (refereegranskat)abstract
- Due to its ability to induce DNA damage in a space and time controlled manner, ionising radiation is a unique tool for studying the mechanisms of DNA repair. The biological effectiveness of ionising radiation is related to the ionisation density which is defined by the linear energy transfer (LET). Alpha particles are characterised by high LET, while X-rays by low LET values. An interesting question is how cells react when exposed to a mixed beam of high and low LET radiation. In an earlier study carried out with human peripheral blood lymphocytes (PBL) we could demonstrate that alpha radiation X-rays interact in producing more chromosomal aberrations than expected based on additivity. The aim of the present investigation was to look at the mechanism of the interaction, especially with respect to the question if it is due to an augmented level of initial damage or impaired DNA repair. PBL were exposed to various doses of alpha particles, X-rays and mixed beams. DNA damage and the kinetics of damage repair was quantified by the alkaline comet assay. The levels of phosphorylated, key DNA damage response (DDR) proteins ATM, p53 and DNA-PK were measured by Western blotting and mRNA levels of 6 damage-responsive genes were measured by qPCR. Alpha particles and X-rays interact in inducing DNA damage above the level predicted by assuming additivity and that the repair of damage occurs with a delay. The activation levels of DDR proteins and mRNA levels of the studied genes were highest in cells exposed to mixed beams. The results substantiate the idea that exposure to mixed beams presents a challenge for the cellular DDR system.
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| 5. |
- Dang, Li, et al.
(författare)
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Radioprotective effect of hypothermia on cells - a multiparametric approach to delineate the mechanisms
- 2012
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Ingår i: International Journal of Radiation Biology. - : Informa UK Limited. - 0955-3002 .- 1362-3095. ; 88:7, s. 507-514
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Low temperature (hypothermia) during irradiation of cells has been reported to have a radioprotective effect. The mechanisms are not fully understood. This study further investigates the possible mechanisms behind hypothermia-mediated radioprotection. Materials and methods: Human lymphoblastoid TK6 cells were incubated for 20 min at 0.8 or 37 degrees C and subsequently exposed to 1 Gy of gamma- or X-rays. The influence of ataxia telangiectasia mutated (ATM)-mediated double-strand break signalling and histone deacetylase-dependent chromatin condensation was investigated using the micronucleus assay. Furthermore, the effect of hypothermia was investigated at the level of phosphorylated histone 2AX (gamma H2AX) foci, clonogenic cell survival and micronuclei in sequentially-harvested cells. Results: The radioprotective effect of hypothermia (called the temperature effect [TE]) was evident only at the level of micronuclei at a single fixation time, was not influenced by the inhibition of ATM kinase activity and completely abolished by the histone deacetylase inhibition. No TE was seen at the level of gamma H2AX foci and cell survival. Conclusions: We suggest that low temperature during irradiation can induce a temporary cell cycle shift, which could lead to a reduced micronucleus frequency. Future experiments focused on cell cycle progression are needed to confirm this hypothesis.
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| 6. |
- Danielsson, Daniel, et al.
(författare)
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Influence of genetic background and oxidative stress response on risk of mandibular osteoradionecrosis after radiotherapy of head and neck cancer
- 2016
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Ingår i: Head and Neck. - : Wiley. - 1043-3074 .- 1097-0347. ; 38:3, s. 387-393
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Tidskriftsartikel (refereegranskat)abstract
- Background: Osteoradionecrosis (ORN) of the mandible is a severe complication of head and neck radiotherapy (RT) treatment, where the impact of individual radiosensitivity has been a suggested explanation. Methods: A cohort of patients with stage II/III ORN was compared to matched controls. Blood was collected and irradiated in vitro to study the capacity to handle radiation-induced oxidative stress. Patients were also genotyped for 8 single-nucleotide polymorphisms (SNPs) in genes involved in the oxidative stress response. Results: A difference in 8-oxo-7,8-dihydro-2-deoxyguanosine (8-oxo-dG) levels was found between the patient cohorts (p = 0.01). The SNP rs1695 in glutathione s-transferase p1 (GSTP1) was also found to be more frequent in the patients with ORN (p = .02). Multivariate analysis of the clinical and biological factors revealed concomitant brachytherapy plus the 2 biomarkers to be significant factors which influense risk of mandibular osteoradionecrosis after radiotherapy of head and neck cancer. Conclusion: The current study indicates that oxidative stress response contributes to individual radiosensitivity and healthy tissue damage caused by RT and may be predicted by biomarker analysis.
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| 7. |
- Gałecki, Maciej, et al.
(författare)
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Precision of scoring radiation-induced chromosomal aberrations and micronuclei by unexperienced scorers
- 2019
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Ingår i: International Journal of Radiation Biology. - : Informa UK Limited. - 0955-3002 .- 1362-3095. ; 95:9, s. 1251-1258
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Dose assessment plays an important role in case of radiological accidents and can be performed by scoring structural changes of chromosome morphology induced in cells by ionizing radiation. The results of such a test are biased by scorer experience, therefore, simple to learn assays are recommended to be used when fast analysis of a large amount of data is needed. The aim of this study was to compare the performance of two radiobiological assays - chromosomal aberrations and micronuclei - by unexperienced scorers with the reference values generated by an expert.Materials and methods: Each participant of an EU-funded two-week radiobiology course was asked to score Chinese hamster ovary cells exposed to gamma radiation up to 4 Gy. The congruence of students' and expert's scores at each dose and the coherence of the dose-response curve parameters between the students were investigated.Results: Micronucleus test tended to be faster and easier to learn than scoring chromosomal aberrations. However, both assays carried out by inexperienced students showed reasonable dose-response curves.Conclusions: In the case of a large radiological accident involving many casualties, the unexperienced scorers would support the process of biodosimetric triage by cytogenetic biological dosimetry.
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| 8. |
- Lisowska, Halina, et al.
(författare)
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Hypothermia modulates the DNA damage response to ionizing radiation in human peripheral blood lymphocytes
- 2018
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Ingår i: International Journal of Radiation Biology. - : Informa UK Limited. - 0955-3002 .- 1362-3095. ; 94:6, s. 551-557
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Low temperature at exposure has been shown to act in a radioprotective manner at the level of cytogenetic damage. It was suggested to be due to an effective transformation of DNA damage to chromosomal damage at low temperature. The purpose of the study was to analyze the kinetics of aberration formation during the first hours after exposing human peripheral blood lymphocytes to ionizing radiation at 0.8 degrees C and 37 degrees C.Materials and methods: To this end, we applied the technique of premature chromosome condensation. In addition, DNA damage response was analyzed by measuring the levels of phosphorylated DNA damage responsive proteins ATM, DNA-PK and p53 and mRNA levels of the radiation-responsive genes BBC3, FDXR, GADD45A, XPC, MDM2 and CDKN1A.Results: A consistently lower frequency of chromosomal breaks was observed in cells exposed at 0.8 degrees C as compared to 37 degrees C already after 30minutes postexposure. This effect was accompanied by elevated levels of phosphorylated ATM and DNA-PK proteins and a reduced immediate level of phosphorylated p53 and of the responsive genes.Conclusions: Low temperature at exposure appears to promote DNA repair leading to reduced transformation of DNA damage to chromosomal aberrations.
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| 9. |
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| 10. |
- Sollazzo, Alice, 1981-, et al.
(författare)
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Alpha particles and X-rays interact in inducing DNA damage in U2OS cells
- 2017
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Ingår i: Radiation Research. - 0033-7587 .- 1938-5404. ; 188:4, s. 400-411
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Tidskriftsartikel (refereegranskat)abstract
- The survivors of atomic bomb explosions in Hiroshima and Nagasaki are monitored for health effect within the Life Span Study (LSS). The LSS results represent the most important source of knowledge about cancer effects of ionizing radiation and they form the basis for the radiation protection system. One uncertainty connected to deriving universal risk factors from these results is related to the problem of mixed radiation qualities. The atomic bomb explosions generated a mixed beam of the sparsely ionizing gamma radiation and densely ionizing neutrons and what is not taken into consideration is the problem of a possible interaction of the two radiation types in inducing biological effects. The existence of such interaction would suggest that the application of risk factors derived from the LSS to predict cancer effects after exposure to pure gamma radiation (such as in the Fukushima prefecture) leads to an overestimation of risk.In order to analyze the possible interaction of radiation types a mixed beam exposure facility was constructed where cells can be exposed to sparsely ionizing X-rays and densely ionizing alpha particles. U2OS cells were used, which are stably transfected with a plasmid coding for the DNA repair gene 53BP1 coupled to a gene coding for the green fluorescent protein GFP. Induction and repair of DNA damage which are known to be related to cancer induction were analyzed. The results suggest that alpha particles and X-rays interact, leading to cellular, and possibly cancer effects not predictable based on assuming simple additivity of the individual mixed beam components.
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