Analysis by alkaline comet assay of cancer patients with severe reactions to radiotherapy: Defective rejoining of radioinduced dna strand breaks in lymphocytes of breast cancer patients

Abstract

Therapeutic exposure to ionising radiation reveals interindividual variations in normal tissue responses. To examine whether a defect in DNA repair capacity might be involved in such hypersensitive phenotypes, we analysed, using the alkaline comet assay, the response as a function of time to in vitro irradiation at 5 Gy of lymphocytes from 17 breast cancer and 9 Hodgkin's disease patients who developed severe reactions to radiotherapy in comparison with 22 patients with ''average'' reactions and 24 healthy donors. A difference between breast cancer over-reactors and both patients with normal reactions and healthy donors was observed 30 and 60 min after exposure. A subgroup of breast cancer over-reactors (7/17) reproducibly demonstrated increased levels of residual damage. When the kinetic analyses were prolonged to 120 min, results were in favour of delayed kinetics of rejoining in these patients. Among Hodgkin's disease over-reactors, only one patient showed defective repair. Interestingly, all patients with the most severe complications (grade 4 RTOG/ EORTC), i.e., 5 breast cancer and 1 Hodgkin's disease, showed impaired rejoining. Our results suggest that impairment in DNA strand break processing may be associated, in specific subgroups of breast cancer patients, with an individual risk of major toxicity of radiation therapy. Thus, the alkaline comet assay appears to be useful for documenting the DNA repair phenotype in cancer patients. Int. J. Cancer 83:83-90, 1999.1999 Wiley-Liss, Inc.

Radiosensitivity in breast cancer assessed by the Comet and micronucleus assays

“…There was a trend toward an increased background level in the cells from both groups of cancer patients, but this failed to reach statistical significance. The Comet data obtained here are in agreement with the findings that the baseline DNA damage levels in nonirradiated peripheral blood lymphocytes from patients with multiple tumours (Müller-Vogt et al, 2003), lung cancer (Rajaee-Behbahani et al, 2001) and breast cancer (Alapetite et al, 1999) are similar to healthy controls. Our results, although without accounting for BRCA1 and BRCA2 mutations, but on a sizeable sample (n ¼ 50) of unselected BC patients, are also in line with the finding of Rothfuß et al (2000) that the Comet assay has not revealed any difference between the in vitro-irradiated cells from four patients with BRCA1 mutation and those from four control subjects.…”

“…In addition, using the Comet assay, we have found the background and induced DNA damage in the peripheral blood lymphocytes from BC patients to be similar to that in control individuals (Djuzenova et al, 1999). Consistent with these data, nonirradiated lymphocytes from patients with multiple tumours (Müller-Vogt et al, 2003), lung cancer (Rajaee-Behbahani et al, 2001) and BC (Alapetite et al, 1999) have also been reported to exhibit the same range of DNA damage as control cells. Similarly, no difference has been revealed by the Comet assay between cells from control subjects and patients with BRCA1 mutation, after irradiation with 2 Gy in vitro (Rothfuß et al, 2000).…”

“…Thus, the TM values of 7.74 and 14.67 in nonirradiated cells from control and BC patients, respectively, obtained by Colleu-Durel et al (2004) are larger some 20 -30-fold than the TM values of 0.47 and 0.45 presented here in Figure 1A. For comparison, the TM values of 1.4 and 1.21 have been found, respectively, for bladder cancer patients and controls (Schabath et al, 2003), whereas TM values of about three have been obtained for both breast cancer patients and controls by Alapetite et al (1999).…”

“…The reasons for the discrepancy might reside in the patients' and controls' cohorts, cancer stage, treatment prior to blood sampling, arbitrary determined cut off values, experimental protocols as well as in interlaboratory variability. Thus, in contrast to the present and several other studies (Alapetite et al, 1999;Rothfuß et al, 2000;Müller-Vogt et al, 2003), in which healthy individuals were used as references, the control group in Hussien et al (2005) includes patients with the benign breast disease. Besides this, even if the same version of the alkaline Comet assay (Singh et al, 1988) was used here and elsewhere (Colleu-Durel et al, 2004;Hussien et al, 2005), the quantitative TM data appear to differ greatly between laboratories.…”

Multiplexed DNA repair assays for multiple lesions and multiple doses via transcription inhibition and transcriptional mutagenesis

“…For personalized disease prevention, FM-HCR might be applied to human blood cells to identify individuals who may have a higher risk of disease. In terms of personalized treatment, the assays might be used to measure DRC in blood cells to predict patient tolerance for a particular cancer therapy (55), or to measure DRC in cancer cells to predict the efficacy of treatment with DNA-damaging chemotherapeutic agents in a manner analogous to using MGMT promoter methylation to predict the response of cancers to alkylating chemotherapy agents, such as temozolomide (56). Indeed, the data in Fig.…”