Evaluation of radioinduced damage and repair capacity in blood lymphocytes of breast cancer patients

Abstract

Genetic damage caused by ionizing radiation and repair capacity of blood lymphocytes from 3 breast cancer patients and 3 healthy donors were investigated using the comet assay. The comets were analyzed by two parameters: comet tail length and visual classification. Blood samples from the donors were irradiated in vitro with a 60 Co source at a dose rate of 0.722 Gy/min, with a dose range of 0.2 to 4.0 Gy and analyzed immediately after the procedure and 3 and 24 h later. The basal level of damage and the radioinduced damage were higher in lymphocytes from breast cancer patients than in lymphocytes from healthy donors. The radioinduced damage showed that the two groups had a similar response when analyzed immediately after the irradiations. Therefore, while the healthy donors presented a considerable reduction of damage after 3 h, the patients had a higher residual damage even 24 h after exposure. The repair capacity of blood lymphocytes from the patients was slower than that of lymphocytes from healthy donors. The possible influence of age, disease stage and mutations in the BRCA1 and BRCA2 genes are discussed. Both parameters adopted proved to be sensitive and reproducible: the doseresponse curves for DNA migration can be used not only for the analysis of cellular response but also for monitoring therapeutic interventions. Lymphocytes from the breast cancer patients presented an initial radiosensitivity similar to that of healthy subjects but a deficient repair mechanism made them more vulnerable to the genotoxic action of ionizing radiation. However, since lymphocytes from only 3 patients and 3 normal subjects were analyzed in the present paper, additional donors will be necessary for a more accurate evaluation.

Potential use of the comet assay in the clinical management of cancer

“…With respect to radiation, several studies have demonstrated higher initial and/or residual DNA damage and lower repair rate following irradiation of PBL in vitro as compared to controls (68,69,(74)(75)(76). Likewise, several studies have shown similar increases in DNA damage and decreases in repair efficiency in response to in vitro treatment with chemical mutagens such as doxorubicin (77), N-methyl N-nitro N-nitrosoguanidine (70), bleomycin (78,79) and benzo(a)pyrene diolepoxide (72).…”

DNA damage induced in human peripheral blood lymphocytes by industrial solid waste and municipal sludge leachates

“…This technique is simple, rapid, relatively inexpensive, and capable of detecting the DNA damage produced by a variety of mutagens in both plant and animal tissues [Tice et al, 2000;Kim et al, 2002]. It has been used for studies in DNA repair [Kim et al, 2002], radiation biology [Nascimento et al, 2001], apoptosis [Singh, 2000], human biomonitoring [Kassie et al, 2000;Dhawan et al, 2001;Faust et al, 2004;Bajpayee et al, 2005, and genetic toxicology [Dhawan et al, 2002;Siddique et al, 2005;Undeger and Basaran, 2005].…”

DNA damage in lymphocytes of rural Indian women exposed to biomass fuel smoke as assessed by the Comet assay

“…The assay is increasingly used in biomonitoring and epidemiological studies [Betti et al, 1994[Betti et al, , 1995Collins et al, 1997;Kassie et al, 2000;Dhawan et al, 2001;Bajpayee et al, 2002;Faust et al, 2004], where it is most often used to detect DNA damage in peripheral lymphocytes. Using the Comet assay, higher levels of DNA damage have been reported among persons exposed to a variety of chemicals [Hartmann et al, 1995;Yuspa and Shields, 1997;Awara et al, 1998;Andreoli et al, 1999;Lei et al, 2004] and ionizing radiation [Singh et al, 1995;Nascimento et al, 2001]. The DNA damage detected by the Comet assay also has been reported to vary with gender [Bajpayee et al, 2002], age [Singh et al, 1990[Singh et al, , 1991, habits, and lifestyle [Betti et al, 1994[Betti et al, , 1995Piperakis et al, 1998;Dhawan et al, 2001;Park et al, 2003;Hininger et al, 2004].…”