25, 0.5, 1.0, 2.0, and 4.0 μM) at different phases of the cell cycle based I-BET-762 in vitro on the protocol described by Cavalcanti et al. (2008) with minor modifications. Doxorubicin (0.5 μM) was used as a positive control. All experimental protocols were performed in the presence or absence of colchicine. In the experimental procedures adopted, when PHT was added after 24 h, cells in both G1 and S stages were exposed, while it can be assumed that when PHT was added after 69 h, cells in G2 stage were exposed. When PHT was added in same time of PHA stimulation (in begin of the culture, 0 h) cells were exposed in G1 stage. In order to obtain

a sufficient number of analyzable metaphases, colchicine was added at a final concentration of 0.0016%, 2 h prior to harvesting. The cells were harvested by centrifugation and treated with 0.075 M KCl at 37 °C for 20 min. The cells were then centrifuged and fixed in 1:3 (v/v) acetic acid:methanol. Finally, slides were prepared, air-dried and stained with 3% Giemsa solution (pH 6.8) for 8 min (Moorhead et al., 1960). Slides were analyzed with a light microscope, and structural and numerical CAs were examined in metaphases from the PHT-treated cultures and from the respective controls. The frequency of CAs (in 100 metaphases per culture) and the mitotic index (MI, number of metaphases per 2.000 lymphocytes per culture) MG-132 clinical trial were determined. The differences between experimental groups were compared by one-way analysis of variance

(ANOVA) followed by Tukey’s test. All analyses were performed using the Graphpad program (Intuitive Software for Science, San Diego, CA). The Alamar Blue assay was performed to evaluate the effect of PHT in human lymphocytes. Based on data collected from three independent experiments carried out in duplicate, the IC50 values obtained in human lymphocytes

for PHT and doxorubicin were 5.68 (4.17–7.28) and 1.78 (0.96–3.31) μM, respectively, after 72 h of incubation (Fig. 2). All subsequent experiments were conducted in human lymphocytes at concentrations of 0.25, 0.5, Quisqualic acid 1.0, 2.0, and 4.0 μM. The alkaline comet assay was used to evaluate induction of single-strand and double-strand breaks (DSB) in human lymphocytes. Fig. 3 shows the effect of PHT on the damage index and on damage frequency, as measured by effects on DNA. At 2.0 and 4.0 μM, PHT clearly produced a significant increase in damage index and damage frequency as compared to the control groups. In addition, this increase in damage score occurred in a dose-related manner. CA analysis was performed to evaluate the clastogenic effects of PHT during G1 (Table 1), G1/S transition (Table 2), and G2 (Table 3) of the cell cycle. In addition, the experimental protocols of the CAs were performed in the presence or absence of colchicine to evaluate the action of PHT in the mitotic phase. PHT was clastogenic in all phases of the cell cycle in the presence or absence of colchicine. Chromatid gaps and chromatid breaks were the most frequent CAs.