engleski

Assessment of irinotecan genotoxicity using the comet assay

Genotoxic effects of two therapeutic concentrations of irinotecan were investigated on isolated human lymphocytes in vitro using the alkaline and neutral comet assay. Using fluorescent staining with ethidium bromide and acridine orange it was found out that irinotecan in vitro causes significant increase of apoptotic cells compared to control, as well as that concentration of 350 mg/m2 of drug caused significantly higher incidence of apoptotic and necrotic cells compared to lower one (180 mg/m2). Four comet parameters: tail length, tail intensity, tail moment and total area were studied and the results indicated that in irinotecan-treated samples they all were increased compared to corresponding controls. DNA damage and repair depend on time as well as on the cell proliferation status. Apoptoses also significantly contributed to the damage levels recorded. Results obtained on lymphocytes indicate that quiescent cells are also susceptible to damage caused by irinotecan, althugh it usually causes S-phase specific cell killing by poisoning the topoisomerase I. Comparison of comet total areas has shown that irinotecan causes similar levels of primary lymphocyte DNA damage, independently of the concentration used, and that its mechanism but not the dosis, was responsiblče for the genotoxicity observed. Both modifications of the comet assay were established as a highly sensitive technique for detection of primary DNA damage and repair. Results obtained also indicate the possibility of their use in preclinical research of antineoplastic drugs.

comet assay; genotoxicity; irinotecan

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