Protective role of metallothionein in benzo[a]pyrene-induced DNA damage

Serum metallothioneins in childhood tumours-a potential prognostic marker

Metallothioneins (MT) are low molecular weight, cysteine-rich proteins maintaining metal ions homeostasis. They play a role in carcinogenesis and may also cause chemoresistance. The aim of the study was to explore the importance of MT serum levels in children suffering from malignant tumours. This prospective study involves examination of 865 samples from 172 patients with malignant tumours treated from 2008 to 2011 at University Hospital Motol. MT serum levels were determined using differential pulse voltammetry-Brdicka reaction. Mean MT level was 2.7 ± 0.5 μM. There was no statistically significant difference between MT levels in different tumours. We also did not find any correlation between MT levels and response to therapy or clinical stages. However, we found a positive correlation between MT levels and age (p = 0.009) and a negative correlation with absolute lymphocyte number (p = 0.001). The fact that patients who had early disease recurrence had lower MT levels during the treatment (complete remission 2.67 vs. recurring 2.34, p = 0.001) seems to be important for clinical practice. Accordingly we believe that there is benefit in further studies of serum MT levels in tumours.

Investigation on the protective effects of cranberry against the DNA damage induced by benzo[a]pyrene

There are few reports that demonstrate the antigenotoxic potential of cranberries. Although the types of berry fruits consumed worldwide are many, this paper focuses on cranberries that are commonly consumed in Mexico (Vaccinium macrocarpon species). The purpose of the present study is to determine whether cranberry ethanolic extract (CEE) can prevent the DNA damage produced by benzo[a]pyrene (B[a]P) using an in vivo mouse peripheral blood micronucleus assay. The experimental groups were organized as follows: a negative control group (without treatment), a positive group treated with B[a]P (200 mg/kg), a group administered with 800 mg/kg of CEE, and three groups treated with B[a]P and CEE (200, 400, and 800 mg/kg) respectively. The CEE and benzo[a]pyrene were administered orally for a week, on a daily basis. During this period the body weight, the feed intake, and the determination of antigenotoxic potential were quantified. At the end of this period, we continued with the same determinations for one week more (recovery period) but anymore administration of the substances. The animals treated with B[a]P showed a weight increase after the first week of administration. The same phenomenon was observed in the lots combined with B[a]P and CEE (low and medium doses). The dose of 800 mg/kg of CEE showed similar values to the control group at the end of the treatment period. In the second part of the assay, when the substances were not administered, these experimental groups regained their normal weight. The dose of CEE (800 mg/kg) was not genotoxic nor cytotoxic. On the contrary, the B[a]P increases the frequency of micronucleated normochromatic erythrocytes (MNNE) and reduces the rate of polychromatic erythrocytes (PE) at the end of the treatment period. With respect to the combined lots, a significant decrease in the MN rate was observed from the sixth to the eighth day of treatment with the two high doses applied; the highest protection (60%) was obtained with 800 mg/kg of CEE. The same dose showed an anticytotoxic effect which corresponded to an improvement of 62.5% in relation to the animals administered with the B[a]P. In the second period, all groups reached values that have been seen in the control group animals. Our results suggest that the inhibition of clastogenicity of the cranberry ethanolic extract against B[a]P is related to the antioxidant capacity of the combination of phytochemicals present in its chemical composition.

Nuclear proteome analysis of benzo(a)pyrene-treated HeLa cells

Previously, we employed a proteomics-based 2-D gel electrophoresis assay to show that exposure to 10μM benzo(a)pyrene (BaP) during a 24 h frame can lead to changes in nuclear protein expression and alternative splicing. To further expand our knowledge about the DNA damage response (DDR) induced by BaP, we investigated the nuclear protein expression profiles in HeLa cells treated with different concentrations of BaP (0.1, 1, and 10μM) using this proteomics-based 2-D gel electrophoresis assay. We found 125 differentially expressed proteins in BaP-treated cells compared to control cells. Among them, 79 (63.2%) were down-regulated, 46 (36.8%) were up-regulated; 8 showed changes in the 1μM and 10μM BaP-treated groups, 2 in the 0.1μM and 10μM BaP-treated groups, 4 in the 0.1μM and 1μM BaP-treated groups, and only one showed changes in all three groups. Fifty protein spots were chosen for liquid chromatography-tandem mass spectrometry (LC-MS/MS) identification, and of these, 39 were identified, including subunits of the 26S proteasome and Annexin A1. The functions of some identified proteins were further examined and the results showed that they might be involved in BaP-induced DDR. Taken together, these data indicate that proteomics is a valuable approach in the study of environmental chemical-host interactions, and the identified proteins could provide new leads for better understanding BaP-induced mutagenesis and carcinogenesis.

Modulatory effects of Thymbra spicata L. different extracts against the mercury induced genotoxicity in human lymphocytes in vitro

Mercury, a xenobiotic metal, is a highly deleterious environmental pollutant. Moreover, in any form mercury is reported to be toxic. On the other hand, Thymbra spicata L., a member of the Lamiaceae family, has long been investigated popularly of biological roles; mainly antimicrobial and antioxidant activities. However, there are very scarce data on the cytogenetic effects of thyme species. The purpose of this study was to investigate the genetic safety of different extracts from T. spicata (water extract, methanol extract, and ethanol extract) and the effects of T. spicata on mercury (as HgCl(2)) induced genotoxicity. Sister chromatid exchange (SCE) and micronucleus (MN) assays were performed to assess DNA damages in cultured human lymphocytes (n = 5). Our results clearly revealed that, the SCE and MN rates induced by HgCl(2) were alleviated by the presence of T. spicata. As conclusion, this study demonstrated for the first time that the T. spicata provided increased resistance of DNA against HgCl(2) induced genetic damage in human lymphocytes. Based on the results of this study, it may be concluded that the T. spicata is a nontoxic material that could be used as a suppressor of heavy metal-induced genotoxicity.

Immunochemical detection of oxidatively damaged DNA

Oxidatively damaged DNA is implicated in various diseases, including neurodegenerative disorders, cancer, diabetes, cardiovascular and inflammatory diseases as well as aging. Several methods have been developed to detect oxidatively damaged DNA. They include chromatographic techniques, the Comet assay, (32)P-postlabelling and immunochemical methods that use antibodies to detect oxidized lesions. In this review, we discuss the detection of 8-oxo-7,8-dihydro-29-deoxyguanosine (8-oxodG), the most abundant oxidized nucleoside. This lesion is frequently used as a marker of exposure to oxidants, including environmental pollutants, as well as a potential marker of disease progression. We concentrate on studies published between the years 2000 and 2011 that used enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry to detect 8-oxodG in humans, laboratory animals and in cell lines. Oxidative damage observed in these organisms resulted from disease, exposure to environmental pollutants or from in vitro treatment with various chemical and physical factors.

Ganoderma applanatum terpenes protect mouse liver against benzo(α)pyren-induced oxidative stress and inflammation

Ganoderma applanatum terpenes (GAT) have been reported to have many benefits and medicinal properties. In this study, we evaluated the protective effect of GAT against benzo(a)pyrene (BaP) induced oxidative stress and inflammation in mouse liver, and explored the potential mechanism of its action. Our data showed that GAT significantly decreased levels of ALT and AST in serum and the liver histological injury in BaP-treated mice. GAT markedly decreased the levels of ROS, MDA and lowered the GSH/GSSG ratio in the liver of BaP-treated mice. Furthermore, GAT markedly inhibited the BaP-induced increase of Cu/Zn-SOD, CAT, GPx and GST activities in the mouse liver. Western blot analysis showed that GAT significantly inhibited inflammation by pressing the expression of IL-1β and COX-2 and inhibiting NF-κB translocation in the liver of BaP-treated mice. In conclusion, these results suggested that GAT could protect the mouse liver against BaP-induced injury by improving hepatic function, attenuating histopathologic changes, decreasing levels of ROS and MDA, renewing the activities of antioxidant enzymes and suppressing inflammatory response.