Initial Damage or Repair as the Major Determinant of Cellular Radiosensitivity?

Peacock, John; Eady, John J.; Edwards, Stephen M.; Holmes, A.; McMillan, Trevor J.; Steel, G. Gordon

doi:10.1080/09553008914551711

Cited by 47 publications

(11 citation statements)

References 6 publications

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“…These sensitive neuroblastoma cell lines are certainly not recovery deficient and therefore may not be deficient in repair of DNA lesions. In this regard the neuroblastoma cells differ from ataxia telangiectasia fibroblasts which, although they are similarly radiosensitive, show less recovery after irradiation than their normal counterpart (Cox, 1982;Peacock et al, 1989). The results that we have obtained indicate the contrast between 'recovery capacity' (which we would identify with the value of P) and 'dose recovery' in a fractionation or low dose-rate treatment.…”

Section: Discussioncontrasting

confidence: 49%

The radiation dose-rate effect in two human neuroblastoma cell lines

Holmes

McMillan²,

Peacock³

et al. 1990

Br J Cancer

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Summary The current use of targeted radiotherapy in the treatment of neuroblastoma has generated a requirement for further information on the radiobiology of these cells. Here we report on studies of the dose-rate effect in two human neuroblastoma cell lines (HX138 and HX142) and the recovery that they demonstrate in split-dose experiments. The sensitivity of the two cell lines to high dose-rate irradiation was confirmed. Surviving fractions at 2 Gy were 0.083 for HX138 anc' 0.11 for HX142. There was little evidence of a dose-rate effect above 2 cGy min-' but significant sparing was seen at lower dose rates. Substantial recovery was seen in split-dose experiments on both cell lines, to an extent that was consistent with the linear quadratic equation. The data were used to derive values for the P parameter of the linear-quadratic equation; the values for the neuroblastomas were higher than for any of the other human tumour cell lines that we have investigated to date. Thus, despite their high sensitivity to ionising radiation HX138 and HX142 do exhibit substantial levels of cellular recovery, suggesting that they may have a significant capacity for repair of radiation-induced lesions.Human neuroblastoma is a childhood tumour which is generally regarded as being radioresponsive even though external-beam radiotherapy plays a minor role in its management (Jacobson et al., 1983). As a result of the relatively specific uptake into these tumours of MIBG, the treatment of patients with systemically-administered '1I-MIBG is increasingly being performed (Pinkerton, 1990). There is therefore a need for more detailed understanding of the response to ionising radiation in neuroblastoma.Recent work in this department has drawn attention to the fact that radiosensitive human tumour cells may not be recovery-deficient (Peacock et al., 1988) and that radiation split-dose recovery increases continuously with dose. We have therefore set out in this study to compare the results of low dose-rate and multiple-dose-level split-dose experiments in two neuroblastoma cell lines. This is the final report of a project from which parts of the data have appeared in an interim form (Peacock et al., 1988. tubes (Falcon). After allowing the agar to set on ice, the cultures were gassed in a 3%, 02, 5% CO2, 92% N2 atmosphere for a minimum of 2 hours and sealed.All Comparison of the data with mathematical models was carried out using methods described previously (Steel et al., 1987). Results Materials and methods Cell linesThe two cell lines used here, HX138 and HX142 were established from xenografted tumour tissue by Dr J.M. Deacon in this department The data on HX142 are at five reduced dose rates ( Figure 3). Again, there is little dose-rate effect for rates in excess of I cGy min-'.Each set of data has been fitted with the linear quadratic equation and the resulting parameters are shown in Table I. Comparison between the cell lines is facilitated by plotting isoeffect curves; Figure 4 shows the dose (DO.01) required to produce a surviving fr...

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Section: Discussioncontrasting

confidence: 49%

The radiation dose-rate effect in two human neuroblastoma cell lines

Holmes

McMillan²,

Peacock³

et al. 1990

Br J Cancer

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“…These have been proposed to be due to differences in non-protein thiol levels (Malaise, 1983), but radiochemical considerations suggest that this is unlikely (Ward, 1990). Radiation hypersensitive AT5BIVA cells do not exhibit increased initial damage (Peacock et al, 1989); instead their radiation sensitivity is considered to be due to a recombination defect (Taylor et al, 1994). Their inclusion in this study was prompted by a desire to provide a contrast to the other cell lines, since the (presuimably) fundamentally different mechanism governing their radiosensitivity should provide an exception to any relationship with GSH we observe in the other cell lines.…”

mentioning

confidence: 99%

Glutathione determination by the Tietze enzymatic recycling assay and its relationship to cellular radiation response

Eady

Orta²,

Dennis³

et al. 1995

Br J Cancer

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S_rnuary Large fluctuations in glutathione content were observed on a daily basis using the Tietze enzyme recycling assay in a panel of six human cell lines of varying radiosensitivity. Glutathione content tended to increase to a maximum during exponential cell proliferation, and then decreased at different rates as the cells approached plateau phase. By reference to high-performance liquid chromatography and flow cytometry of the fluorescent bimane derivative we were able to verify that these changes were real. However, the Tietze assay was occasionally unable to detect glutathione in two of our cell lines (MGH-Ul and AT5BIVA), although the other methods indicated its presence. The existence of an inhibitory activity responsible for these anomalies was confirmed through spiking our samples with known amounts of glutathione. We were unable to detect a direct relationship between cellular glutathione concentration and aerobic radiosensitivity in our panel of cell lines.Keyworid glutathione; radiosensitivity; Tietze assay; high-performance liquid chromatography For at least the past decade the tripeptide sulphydryl compound glutathione (GSH) has been the subject of intensive investigation regarding its role in mediating both radiationand drug-induced responses in living cells. GSH has been proposed to act in a vast number of different cellular processes, amongst them the maintenance of a suitable intracellular reductive environment, protection against harmful xenobiotics, a catalyst of or reactant in several metabolic schemes and an intracellular store of cysteine (Nygaard and Simic, 1983;Mitchell and Russo, 1987). Its potential importance for radiobiology has been recognised ever since the development of the competition model for radiation cell killing, a mathematical consequence of the reaction rates for competing reactions (Alper and Howard-Flanders, 1956). DNA radicals produced by irradiation are considered to be subject to a competition between oxidising (or electronaffinic) agents, leading to damage fixation and ultimate cell death, and reducing species (such as sulphydryl compounds) which, through hydrogen atom donation would facilitate damage repair and so lead to continued cell viability, against a background of the intramolecular decay of DNA radicals to render them non-restorable (Koch, 1983). Since the rate of reaction between oxygen and DNA radicals is far greater than that between GSH and DNA radicals (Bump and Brown, 1990), the competition theory predicts that under normal aerobic conditions the former reaction would dominate, rendering unimportant any changes in GSH content. However GSH may nevertheless play a significant role in the aerobic radiation response, its protective effects mediated through other processes limiting radiation damage, for instance the detoxification of radiation-induced hydroperoxides (Dethmers and Meister, 1981;Biaglow et al., 1984).Cells may be depleted of GSH by treatment with the specific enzyme inhibitor DL-buthionine-S,R-sulphoximine (BSO) which prevents GSH synthesi...

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“…DNA double strand breaks (dsbs) are considered to be closely related to cell death because it is suggested that they can lead directly to chromosome aberration and the loss of genetic material [22]. To date, the correlation between radiosensitivity and DNA damage in many tumor cell lines has been studied [25,[27][28][29][30][31]36]. The various experimental approaches used for the detection of DNA strand breaks are filter elution, constant field gel electrophoresis, pulsed-field gel electrophoresis (PFGE) and the comet assay [25].…”

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The Relationship between Cellular Radiosensitivity and Radiation-Induced DNA Damage Measured by the Comet Assay

Wada

Kurahayashi

Kobayashi

et al. 2003

The Journal of Veterinary Medical Science

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ABSTRACT. The relationship between deoxyribonucleic acid (DNA) damage and the cell death induced by γ-irradiation was examined in three kinds of cells, Chinese hamster ovary fibroblast CHO-K1, human melanoma HMV-II and mouse leukemia L5178Y. Cell survival was determined by a clonogenic assay. The induction and rejoining of DNA strand breaks induced by radiation were measured by the alkaline and neutral comet assays. L5178Y cells were the most radiosensitive, while CHO-K1 cells and HMV-II cells were radioresistant. There was an inverse relationship between the survival fraction at 2 Gy (SF2) and the yield of initial DNA strand breaks per unit dose under the alkaline condition for the comet assay, and also a relationship between SF2 and the residual DNA strand breaks (for 4 hr after irradiation) under the neutral condition for the comet assay, the latter being generally considered to be relative to cellular radiosensitivity. In the present analysis, it was considered that the alkaline condition for the comet assay was optimal for evaluating the initial DNA strand breaks, while the neutral condition was optimal for evaluating the residual DNA strand breaks. Since the comet assay is simpler and more rapid than other methods for detecting radiation-induced DNA damage, this assay appears to be a useful predictive assay for evaluating cellular clonogenic radiosensitivity of tumor cells. KEY WORDS: comet assay, DNA strand break, γ-irradiation, predictive assay, radiosensitivity.J. Vet. Med. Sci. 65(4): 471-477, 2003 Different types of cell lines show different radiosensitivities. In addition, even a tumor of the same origin and pathology, can show radiosensitivity over quite a wide range [4], and therefore, understanding the radiosensitivity of an individual tumor is of great importance in the clinical situation. Knowledge of the intrinsic radiosensitivities of cells from a tumor biopsy can help produce an optimized radiotherapy protocol for individual patients.Reproductive death measured by a clonogenic assay is an important index for the cell death induced by radiation, and the cellular radiosensitivities of fibroblasts and tumor cells have been evaluated by a clonogenic assay [13,17]. A good correlation was found between the reproductive death of fibroblasts measured by the clonogenic assay and the severity of late normal tissue effects, such as fibrosis and erythema, after radiotherapy [7,14]. However, this clonogenic assay consumes a lot of time, and the cells must be proliferated in vitro [4,14]. Hence this assay is not optimal for routine clinical use, and thus there is now much interest in exploiting a more rapid and simple assay to evaluate cellular radiosensitivity [8,25].It is said that the cell death caused by radiation is due to deoxyribonucleic acid (DNA) damage [29]. DNA double strand breaks (dsbs) are considered to be closely related to cell death because it is suggested that they can lead directly to chromosome aberration and the loss of genetic material [22]. To date, the correlation between radiose...

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Initial Damage or Repair as the Major Determinant of Cellular Radiosensitivity?

Cited by 47 publications

References 6 publications

The radiation dose-rate effect in two human neuroblastoma cell lines

The radiation dose-rate effect in two human neuroblastoma cell lines

Glutathione determination by the Tietze enzymatic recycling assay and its relationship to cellular radiation response

The Relationship between Cellular Radiosensitivity and Radiation-Induced DNA Damage Measured by the Comet Assay

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