Irinotecan Toxicity to Human Blood Cells in vitro: Relationship between Various Biomarkers

Abstract

Toxic effects of the antineoplastic drug irinotecan on human blood cells at concentrations of 9.0 µ g/ml and 4.6 µ g/ml were evaluated in vitro . Using the alkaline and neutral comet assay significantly increased levels of primary DNA damage in lymphocytes were detected. The induction of apoptosis/necrosis, as determined by a fluorescent assay, was also notably increased. Cytogenetic outcomes of the treatment were assessed by the analysis of structural chromosome aberrations and fluorescence in situ hybridization. A significantly higher incidence of chromatid breaks and complex quadriradials was observed. Painted chromosomes 1, 2 and 4 were equally involved in translocations, but only the chromosome 1 was involved in the formation of quadriradials. Sister chromatid exchange analysis was performed in parallel with the analysis of lymphocyte proliferation kinetics. The higher concentration of irinotecan caused almost seven-time increase, while the lower one caused a five-time increase of the basal sister chromatid exchange frequency, accompanied with significant lowering of the lymphocyte proliferation index. Using the cytokinesis-block micronucleus assay, a dose-dependent increase in micronucleus frequency along with the formation of nuclear buds and nucleoplasmic bridges was noticed. Inhibitory effects of irinotecan on enzyme acetylcholinesterase (AChE) were studied in erythrocytes. An IC 50 value of 5.0 × 10 − 7 was established. Irinotecan was found to be strong inhibitor of the acetylcholine hydrolysis and to cause a continuous decrease of catalytic activity of AChE. The results obtained on a single donor may contribute to the understanding of irinotecan toxicity, but further in vitro and in vivo studies are essential in order to clarify remaining issues, especially on possible interindividual variability in genotoxic responses to the drug. Irinotecan (7-ethyl-10-[4-(1-piperidino)-1-piperidino] carbonyloxycamptothecin; CPT-11) is clearly one of the most important new anticancer drugs developed in the last few decades. It is a member of the camptothecin drug family [1]. Irinotecan is a pro-drug that is biotransformed by tissue and serum carboxylesterases to an active metabolite, SN-38 (7-ethyl-10-hydroxycamptothecin) that has a 100-1000-time higher cytotoxic and antitumour activity [2]. It acts as an inhibitor of the nuclear enzyme topoisomerase I, which is involved in cellular DNA replication and transcription. During replication, topoisomerase I mediates the relaxation of super-coiled DNA, and its inhibition results in breakage of the DNA chain and likely induces apoptosis. Irinotecan and SN-38 both bind to the topoisomerase I-DNA complex and prevent religation of single-strand breaks [3]. Irinotecan has undergone extensive clinical investigation worldwide and demonstrated potent activity against many types of human cancer, but is particularly active in the treatment of gastrointestinal and pulmonary malignancies [1][2][3][4].The principal dose-limiting toxicity of irinotecan is diarrhoea. It either...

Synergistic Effects of Irinotecan and Flavonoids on Ehrlich Ascites Tumour-Bearing Mice

“…It is reasonable to assume that mice surviving more than 50 days eliminated Ehrlich ascites tumour cells because of the combined activity of irinotecan and the beneficial effects of flavonoids, which, based on our results, possess immunomodulating activity. Immunomodulating activity of these compounds was also reported earlier [30–33].…”

“…As one of the most frequently used anti‐tumour drugs, it is particularly active in the treatment of gastrointestinal and pulmonary malignancies [1–4]. However, treatment with irinotecan is often accompanied by side effects, especially those related with cholinergic effects in the gastrointestinal tract and haematological toxicity [31].…”

“…As one of the most frequently used anti-tumour drugs, it is particularly active in the treatment of gastrointestinal and pulmonary malignancies [1][2][3][4]. However, treatment with irinotecan is often accompanied by side effects, especially those related with cholinergic effects in the gastrointestinal tract and haematological toxicity [31]. Our main goal was to establish whether the administration of quercetin and naringin might overcome the negative influences of chemotherapy with irinotecan in Ehrlich ascites tumour-bearing mice and also to find possible synergistic effects of these dietary phytochemicals with a known antitumour drug.…”

Assessment of Cyto/Genotoxicity of Irinotecan in V79 Cells Using the Comet, Micronucleus, and Chromosome Aberration Assay

“…Aydemir and Bilaloglu (33) found an increase in MN frequency in the bone marrow cells of mice treated with topotecan (an analogue of irinotecan). Kopjar et al (14) found a signifi cant increase in the MN frequency in human lymphocytes even at a lower dose of 4.6 µg mL -1 of irinotecan.…”

“…al. (14), tested the toxicity of 4.6 µg mL -1 and 9 µg mL -1 irinotecan on human blood cells, and also reported higher cytotoxicity at a lower dose of the drug. The other possible explanation for our results could be the apoptotic elimination of cells whose DNA was not repaired.…”