Assessment of bendamustine-induced genotoxicity in eukaryotic cells.

Bendamustine, an anticancer drug with alkylating properties, is widely used to treat hematological malignancies. Since the nitrogen mustard family alkylators induce DNA damages and have been associated with an elevated risk of second malignancy, current study evaluates the cytotoxic, mutagenic, and recombinogenic effects of bendamustine by using, respectively the mitotic index assay, the in vitro mammalian cell micronucleus test (Mnvit) and the chromosome aberration (CA) test in human peripheral lymphocytes, and the in vivo homozygotization assay in Aspergillus nidulans, which detects the loss of heterozygosity (LOH) due to somatic recombination. Bendamustine (6.0 µg/ml, 9.0 µg/ml, and 12.0 µg/ml) induced a statistically significant concentration-related increase in the frequencies of micronuclei and a significant reduction in the cytokinesis block proliferation index (CBPI) rates when compared to negative control. In the CA test, bendamustine significantly increased the frequencies of structural aberrations at the three tested concentrations when compared to the negative control. Aspergillus nidulans diploids, obtained after bendamustine treatment (6.0 µg/ml, 12.0 µg/ml, and 24.0 µg/ml), produced, after haploidization, homozygotization index (HI) rates higher than 2.0 and significantly different from the negative control. Since bendamustine showed genotoxic effects in all tested concentrations, two of them corresponding to the peak plasma concentrations observed in cancer patients treated with bendamustine, data provided in the current research work may be useful to identify the most appropriate dosage regimen to achieve the efficacy and safety of this anticancer medication.

Genotoxic investigation of a thiazolidinedione PPARγ agonist using the in vitro micronucleus test and the in vivo homozygotization assay.

Pioglitazone (PTZ) is an oral antidiabetic agent whose anti-cancer properties have been described recently. Since PTZ increases the production of reactive oxygen species in mammalian cells, the aim of current study was to evaluate the cytotoxic, mutagenic and recombinogenic effects of PTZ using respectively the in vitro mitotic index assay and the in vitro mammalian cell micronucleus test in human peripheral lymphocytes, and the in vivo homozygotization assay in Aspergillus nidulans, which detects the loss of heterozygosity due to somatic recombination. Although the lowest PTZ concentrations (4-36 µM) did not show any significant rise in the micronucleus production, the higher PTZ concentration (108 µM) produced a statistically higher number of micronuclei than the negative control and significantly altered the cell-proliferation kinetics, demonstrating the mutagenic and antiproliferative effects of PTZ, respectively. The recombinogenic activity of PTZ, demonstrated here for the first time, was observed at the highest tested concentration (400 µM) through the homozygotization index rates significantly different from the negative control. Taken together, our results show that PTZ is genotoxic at a concentration higher than the therapeutic plasma concentration. This PTZ genotoxicity may be a potential benefit to its previously described antitumour activity.