Anja Haverić

The HUman MicroNucleus project on eXfoLiated buccal cells (HUMNXL): The role of life-style, host factors, occupational exposures, health status, and assay protocol

The human buccal micronucleus cytome assay (BMCyt) is one of the most widely used techniques to measure genetic damage in human population studies. Reducing protocol variability, assessing the role of confounders, and estimating a range of reference values are research priorities that will be addressed by the HUMN(XL) collaborative study. The HUMN(XL) project evaluates the impact of host factors, occupation, life-style, disease status, and protocol features on the occurrence of MN in exfoliated buccal cells. In addition, the study will provide a range of reference values for all cytome endpoints. A database of 5424 subjects with buccal MN values obtained from 30 laboratories worldwide was compiled and analyzed to investigate the influence of several conditions affecting MN frequency. Random effects models were mostly used to investigate MN predictors. The estimated spontaneous MN frequency was 0.74‰ (95% CI 0.52-1.05). Only staining among technical features influenced MN frequency, with an abnormal increase for non-DNA-specific stains. No effect of gender was evident, while the trend for age was highly significant (p<0.001). Most occupational exposures and a diagnosis of cancer significantly increased MN and other endpoints frequencies. MN frequency increased in heavy smoking (≥40cig/day, FR=1.37; 95% CI 1.03-.82) and decreased with daily fruit consumption (FR=0.68; 95% CI 0.50-0.91). The results of the HUMN(XL) project identified priorities for validation studies, increased the basic knowledge of the assay, and contributed to the creation of a laboratory network which in perspective may allow the evaluation of disease risk associated with MN frequency.

Micronuclei frequencies in peripheral blood and buccal exfoliated cells of young smokers and non-smokers

Cytogenetic biomarkers, such as micronuclei in peripheral blood or oral mucosa, are widely used for evaluation of exposure to genotoxins or carcinogens. Tobacco is one of the strongest carcinogens, responsible for development of different types of cancers. The aim of this study was to assess the genotoxicity of cigarette consumption in young smokers and to correlate results of cytogenetic analysis in peripheral blood lymphocytes and exfoliated buccal cells. The study was conducted on samples taken from 43 smokers and 44 non-smokers, young individuals from Bosnia and Herzegovina. Significantly higher frequency of micronuclei in peripheral blood lymphocytes was observed in smokers (p < 0.05). No significant correlations were found for age, duration and intensity of smoking, and frequency of micronuclei in lymphocytes. Significantly higher frequency of degenerated (apoptotic) buccal cells was also revealed in smokers (p < 0.05). The frequency of apoptotic cells in smokers was significantly influenced by the age of participants (F = 8.649; p < 0.01) and duration of smoking (F = 5.389; p < 0.05). Results of cytogenetic analysis conducted in peripheral blood and exfoliated buccal cells are in significant positive correlation, indicating complementarities of those analyses.

Effects of dipotassium trioxohydroxytetrafluorotriborate (K2[B3O3F4OH]) on genetic material and inhibition of cell division in human cell cultures

We have examined antiproliferative, cytotoxic, and genotoxic potential of a halogenated boroxine dipotassium trioxohydroxytetrafluorotriborate [K2(B3O3F4OH)]. The impact on cell growth was evaluated by alamarBlue assay in basal cell carcinoma culture. Cytostatic, cytotoxic, and genotoxic potential were evaluated in lymphocytes culture, applying cytokinesis-block micronucleus cytome assay and chromosome aberrations analysis. Tested concentrations (0.05, 0.1, 0.2, and 0.4 mg/mL) were correlated with inhibition of cell growth in basal cell carcinoma culture and with the lymphocytes proliferation. Clastogenic activity has been confirmed, without evidences of aneugenic activity, in human lymphocytes.

Inhibitory effects of delphinidin and luteolin on genotoxicity induced by K2(B3O3F4OH) in human lymphocytes in vitro

Abstract The genotoxicity of halogenated boroxine [K2(B3O3F4OH)], a novel compound with the potential for prevention and/or treatment of various skin changes, has been confirmed in human lymphocytes. The potential of luteolin and delphinidin in inhibition of the genotoxic and cytotoxic effects of halogenated boroxine in vitro was analyzed applying the chromosome aberration analysis and the cytokinesis-block micronucleus cytome assay in human lymphocyte cultures. The in vitro treatments included addition of boroxine and flavonoids independently, and combined treatments of boroxine with luteolin or delphinidin. In the concentration of 50 μM, luteolin significantly decreased the frequency of micronuclei and nuclear buds. Delphinidin suppressed the occurrence of aberrant cells in the presence of the halogenated boroxine, but also affected their induction in respective delphinidin treatment. Detection of endoreduplications in combined treatments indicated that these flavonoids are potential inhibitors of cell cycle or topoisomerase II activity. The obtained results have confirmed antigenotoxic activity of selected bioflavonoids in vitro. The side effects of potential therapeutic applications of halogenated boroxine may be inhibited in the presence of bioflavonoids in appropriate dosage.

Antioxidant and antiproliferative activities of Helleborus odorus Waldst. & Kit, H. multifidus Vis. and H. hercegovinus Martinis

This study was undertaken in order to evaluate possible antioxidative and antiproliferative activities of three Helleborus taxa. The dry leaves and roots of three Helleborus taxa were extracted with ethanol and water. A phytochemical evaluation of the selected extracts was performed using spectrophotometric methods and a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity assay was used for measuring the antioxidative activity of extracts. The antiproliferative activity of the three Helleborus taxa was studied using Burkitts lymphoma B cells (BJAB) cell lines. The phytochemical evaluation showed that the leaves contain high levels of total phenolic and flavonoid content. Results from the DPPH assay indicated that the activity of the ethanol and water extracts of the leaves was higher than that of positive control (thymol). Extracts from the roots of H. odorus also displayed higher antioxidant activity than the positive probe, while H. mulifidus and H. hercegovinus root extracts were less effective. A statistically significant correlation between total phenolic content and antioxidative properties indicates that these compounds contribute to the antioxidant activity. The highest percentage of cell growth inhibition was observed when testing the water root extracts of H. multifidus (50.14%) and H. hercegovinus (49.04%). In contrast, the water leaf extract of H. hercegovinus exhibited the lowest inhibition of cell growth (8.59%), although it showed strong antioxidant activity.

Cytogenetic evaluation of paracetamol effects in human lymphocytes culture.

Paracetamol is a common analgesic and antipyretic drug. It has been recognized as one of the most ordinary medications taken in overdoses. We examined the possible genotoxic effects of high paracetamol concentrations expected to occur after overdose. Paracetamol was added to the cultures at the beginning of the cultivation period. Separate cultures for three tested concentrations of paracetamol (50 μg/mL, 100 μg/mL, and 200 μg/mL) were set. Effects of paracetamol were evaluated by micronucleus cytokinesis-block assay, chromosome aberration analysis, and nuclear division index. Results demonstrate that paracetamol concentration of 200 μg/mL expresses certain genotoxic effects in human peripheral blood lymphocytes.

Cytotoxic and genotoxic activity of some Helleborus species.

Despite their known toxic properties, various Helleborus species are used as medicaments in folk medicine to treat some diseases and health conditions. As the main mechanism of many cytostatic drugs is based on their cytotoxic activity, there is potential for the toxicity of hellebore to be used in anticancer therapy. This study tested the geno- and cytotoxic effects of extracts of three hellebore taxa (Helleborus odorus, Helleborus multifidus and Helleborus hercegovinus) on meristemic onion (Alliumcepa L.) cells and human lymphocytes. Treatments with Helleborus extracts induced cytotoxic and cytostatic effects in meristemic onion cells as well as in cultivated cytokinesis-blocked human lymphocytes. Cytokinesis-block micronucleus cytome assay indicated that treatments with hellebore extracts induce genotoxic effects in human lymphocytes, and that the significant mechanism of their antiproliferative activity is apoptosis induction.

Effects of dipotassium-trioxohydroxytetrafluorotriborate, K2[B3O3F4OH], on cell viability and gene expression of common human cancer drug targets in a melanoma cell line.

Abstract Recently it was found that dipotassium-trioxohydroxytetrafluorotriborate, K2(B3O3F4OH), is a potent and highly specific inhibitor of precancerous cell processes. We conducted gene expression profiling of human melanoma cells before and after treatment with two concentrations (0.1 and 1 mM) of this boron inorganic derivative in order to assess its effects on deregulation of genes associated with tumor pathways. Parallel trypan blue exclusion assay was performed to assess the cytotoxicity effects of this chemical. Treatment with K2(B3O3F4OH) induced a significant decrease of cell viability in melanoma cellline at both tested concentrations. Furthermore, these treatments caused deregulation of more than 30 genes known as common anti-tumor drug targets. IGF-1 and hTERT were found to be significantly downregulated and this result may imply potential use of K2(B3O3F4OH) as an inhibitor or human telomerase and insulin-like growth factor 1, both of which are associated with various tumor pathways.

Genotoxicity and cytotoxicity analysis of curcumin and sunset yellow in human lymphocyte culture

Genotoxic and cytotoxic effects of curcumin and sunset yellow were tested by the chromosome aberration analysis and cytokinesis-block micronucleus cytome assay in human lymphocyte culture. Water solutions of food dyes, in concentrations of 1, 2, 4 and 8 mM, were added to the cultures at the beginning of the cultivation period. Concentrations of 4 and 8 mM of sunset yellow induced significant increase in frequencies of cells with chromosome aberrations. Tested concentrations of sunset yellow significantly associated with frequencies of structural aberrations, chromatid-type aberrations, total aberrant cells and micronuclei showing considerable dose dependent clastogenic activity. In higher analyzed concentrations, curcumin significantly increased only nuclear buds frequency, suggesting its potential genotoxicity, while sunset yellow showed dose-dependent genotoxic potential. Obtained results point toward favorization of natural coloring agents in food consumption and emphasize the need of controlled use of food colorants.

Genotoxicity Evaluation of Dipotassium -Trioxohydroxytetrafluorotriborate, K2(B3O3F4OH), in Human Lymphocyte Cultures and Mice Reticulocytes

Genotoxic effects of inorganic molecule dipotassium-trioxohydroxytetrafluorotriborate, K2(B3O3F4OH), a promising new therapeutic for the epidermal changes treatment, have been evaluated. In vitro analysis included evaluation of genotoxic and cytotoxic potential of K2(B3O3F4OH) in concentrations of 0.01, 0.02, 0.05 and 0.06 mg/mL applying cytokinesis-block micronucleus cytome assay in human lymphocyte culture. With the increase of concentration the frequency of micronuclei elevated but the differences were not significant. Also, there were no significant differences among the frequencies of nuclear buds and nucleoplasmic bridges between controls and treated cultures. Nuclear division index and nuclear division cytotoxycity index values did not reveal significant cytotoxic effect of K2(B3O3F4OH). In vivo genotoxic effects were analyzed on BALB/c mice applying reticulocytes micronucleus assay. K2(B3O3F4OH) was administrated intraperitoneally in final concentrations of 10, 20, 50 and 55 mg/kg. Significant decrease of reticulocytes ratio and increase of micronuclei frequencies against pre-treatments were found for both sampling periods of 48 and 72 hours of the highest applied concentration. This study confirmed that K2(B3O3F4OH) is not genotoxic in tested concentrations in vitro as well as in concentrations lower than 55 mg/kg in vivo. This study presents a reliable basis for further pre-clinical and potential clinical investigations.