Celastrol pretreatment as a therapeutic option against cisplatin-induced nephrotoxicity.

Celastrol is a natural bioactive compound extracted from the medicinal plant Tripterygium wilfordii Hook F. It exhibits immunosuppressive, anti-inflammatory, and antioxidant activities. Cisplatin is a commonly used chemotherapeutic drug in the treatment of a wide range of tumors. Although very effective therapeutically, it can cause nephrotoxicity leading to dose reduction or discontinuation of treatment. This study aims to clarify the therapeutic potential of celastrol in cisplatin-induced nephrotoxicity. The possible protective effects of celastrol pretreatment against cisplatin-induced oxidative stress and genotoxicity were investigated. A rat kidney epithelial cell line NRK-52E was pretreated with the desired concentrations of celastrol (200 nM, 100 nM, and 50 nM) for 24 h. The cells were treated with 50 µM cisplatin for a further 24 h to see whether cisplatin caused the same or less toxicity compared to the vehicle control group. Alkaline comet assay was performed for genotoxicity assessment. Genotoxicity evaluation revealed that celastrol caused a statistically significant reduction in DNA damage. Oxidative stress parameters were evaluated by measuring the glutathione (GSH) and protein carbonyl (PC) levels and also by measuring the enzyme activities of glutathione peroxidase (GPx), glutathione reductase (GR), catalase (CAT) and superoxide dismutase (SOD) enzymes. Celastrol pretreatment increased the GSH content of the cells and ameliorated the protein carbonylation level. Likewise, celastrol pretreatment improved the GR and CAT activities. However, no significant difference was observed in GPx and SOD activities. In the light of these findings, celastrol treatment could be a therapeutic option to reduce cisplatin-induced nephrotoxicity. Further studies are needed for the clarification of its therapeutic potential.

Stanozolol administration combined with exercise leads to decreased telomerase activity possibly associated with liver aging.

Anabolic agents are doping substances which are commonly used in sports. Stanozolol, a 17α­alkylated derivative of testosterone, has a widespread use among athletes and bodybuilders. Several medical and behavioral adverse effects are associated with anabolic androgenic steroids (AAS) abuse, while the liver remains the most well recognized target organ. In the present study, the hepatic effects of stanozolol administration in rats at high doses resembling those used for doping purposes were investigated, in the presence or absence of exercise. Stanozolol and its metabolites, 16­ß­hydroxystanozolol and 3'­hydroxystanozolol, were detected in rat livers using liquid chromatography­mass spectrometry (LC­MS). Telomerase activity, which is involved in cellular aging and tumorigenesis, was detected by examining telomerase reverse transcriptase (TERT) and phosphatase and tensin homolog (PTEN) expression levels in the livers of stanozolol­treated rats. Stanozolol induced telomerase activity at the molecular level in the liver tissue of rats and exercise reversed this induction, reflecting possible premature liver tissue aging. PTEN gene expression in the rat livers was practically unaffected either by exercise or by stanozolol administration.

How Does Infection with Human Papillomavirus 16 and 18 Impact on DNA Damage and Repair in Cervical Cells and Peripheral Blood?

Human papillomavirus (HPV) infection is one of the most common sexually transmitted diseases worldwide and a prime cause of cervical cancer. The HPV DNA is detected in approximately 80-90% of all cervical cancers, with HPV 16 and 18 being the high risk conferring human carcinogens. DNA damage and diminished DNA repair mechanisms are potential biological surrogates of HPV infection that warrant further research in different tissues and populations. Notably, we do not know the extent to which the high risk HPV 16 and 18 differentially affect cervical cells versus other systems such as peripheral blood lymphocytes (PBLs). We evaluated DNA damage and repair in women who tested positive for HPV 16 or HPV 18 and healthy control women without HPV 16 or HPV 18 infection. We found that the DNA damage as measured by the Comet assay was markedly greater in cervical cells of women with HPV 16 (mean: 8.1 as% DNA in tail, 95% CI: 7.6-8.7) or HPV 18 infection (mean: 9.6, 95% CI: 8.9-10.2) than controls (mean: 6.7, 95% CI: 6.2-7.4) (p < 0.05). By contrast, in PBLs, we did not find a significant difference in DNA damage between women with HPV 16 or 18 infection versus controls, as measured by the Comet assay or the Conventional Chromosomal Aberration analysis (p > 0.05). We observed, however, the DNA repair capacity, as measured by the X-ray induced challenge (XRC) assay, was significantly impaired in PBLs from women with HPV 16 or 18 infection compared to controls (p < 0.05). This is the first comparative study, to the best of our knowledge, suggesting that the cervical swab cells might be better suited than peripheral lymphocytes as biosamples for detection of HPV 16 or 18 biological effects on DNA damage. In addition, these findings suggest that the Comet assay performed only in PBLs may potentially lead to false negative diagnosis of DNA damage. Taken together, these observations contribute to development of future diagnostic innovation and precision sampling strategies for robust detection of the biological effects of HPV 16 or 18 in women. We conclude by a brief discussion of implications for HPV clinical diagnostics and precision medicine innovation.

Effects of 3-monochloropropane-1,2-diol (3-MCPD) and its metabolites on DNA damage and repair under in vitro conditions.

3-monochloropropane-1,2-diol (3-MCPD) is a food contaminant that occurs during industrial production processes and can be found mainly in fat and salt containing products. 3-MCPD has exhibited mutagenic activity in vitro but not in vivo, however, a genotoxic mechanism for the occurrence of kidney tumors has not so far been excluded. The main pathway of mammalian 3-MCPD metabolism is via the formation of ß--chlorolactatic acid and formation of glycidol has been demonstrated in bacterial metabolism. The aim of this study was to investigate genotoxic and oxidative DNA damaging effects of 3-MCPD and its metabolites, and to provide a better understanding of their roles in DNA repair processes. DNA damage was assessed by alkaline comet assay in target rat kidney epithelial cell lines (NRK-52E) and human embryonic kidney cells (HEK-293). Purine and pyrimidine base damage, H2O2 sensitivity and DNA repair capacity were assessed via modified comet assay. The results revealed in vitro evidence for increased genotoxicity and H2O2 sensitivity. No association was found between oxidative DNA damage and DNA repair capacity with the exception of glycidol treatment at 20 µg/mL. These findings provide further insights into the mechanisms underlying the in vitro genotoxic potential of 3-MCPD and metabolites.

Risk assessment for children exposed to DDT residues in various milk types from the Greek market.

The occurrence of residues of DDT and its metabolites was monitored in 196 cow milk samples of various pasteurized commercial types collected from the Greek market. Residue levels were determined by GC-MS analysis. In 97.4% of the samples at least one DDT isomer or one of the DDT metabolites was detected, in levels not exceeding the maximum permitted residue level by the EU. Hazard Index for both carcinogenic and non-carcinogenic effects was estimated under two assumptions: a) using DDT concentrations from positive samples and b) imputing LOD/2 as an arbitrary concentration for negative samples. No statistically significant differences in detected or summed residue (p > 0.05) concentrations between different milk types were observed, with the exception of specific metabolites of DDT in some milk types. Exposure assessment scenarios were developed for children aged 1, 3, 5, 7 and 12 years old based on estimated body weights and daily milk consumption. Hazard Indices for non-carcinogenic effects were below 0.109 covering also carcinogenic effects according to WHO approach. The cancer risk values for carcinogenic effects according to the US EPA Cancer Benchmark Concentration approach, ranged from 0.4 to 18. For both effects the highest values were calculated for the 1- to 3-year-old age groups.

Assessment of individual susceptibility to baseline DNA and cytogenetic damage in a healthy Turkish population: evaluation with lifestyle factors.

BACKGROUND: Cytogenetic biomarkers are most frequently used well-established endpoints in human population studies with their sensitivity for measuring exposure to genotoxic agents. They have an important role as early predictors of cancer risk. Identification of individual genotypes of metabolic gene polymorphisms helps to understand the modulation of cancer susceptibility by environmental exposures, such as cigarette smoking and other lifestyle factors. AIM: To evaluate individual susceptibility to chemicals, we determined individual DNA damage related to glutathione S-transferase (GST) genotypes (GSTM1, GSTT1, and GSTP1) in a Turkish population. METHODS: Peripheral blood lymphocytes (PBL) and DNA samples of 127 subjects were analyzed for the presence of DNA damage, using single-cell gel electrophoresis (the Comet assay), and for cytogenetic parameters (chromosomal aberrations [CAs], bleomycin-induced CA, and a cytokinesis-blocked micronucleus assay), and the polymerase chain reaction/restriction fragment length polymorphism method, respectively. RESULTS: Individuals carrying a GSTT1-null allele showed higher frequencies of CA and micronucleus (MN) (p=0.026, p=0.003, respectively), whereas the GSTM1-null and GSTP1 mutant genotypes did not show any differences in cytogenetic parameters. Our findings demonstrated that none of the lifestyle factors (smoking, alcohol drinking, dietary habits, vitamin intake, and physical activity), except for vitamin intake (p=0.002), were significantly associated with the studied cytogenetic parameters. CONCLUSION: Our results suggest that the GSTT1 gene polymorphism may influence the baseline cytogenetic frequency in a healthy population.

Assessment of DNA damage in postmenopausal women under hormone replacement therapy.

OBJECTIVE: To evaluate the possible DNA damage in peripheral blood leukocytes of postmenopausal women under different hormone replacement therapies (HRT), comet assay, a standard method for assessing genotoxicity has been used. METHOD: 46 women were categorized in three groups-Group A: 15 surgical menopausal women who underwent surgery for benign conditions, receiving conjugated equine estrogen, 0.625 mg/day (CEE) for 2.3 +/- 1.5 years, Group B: 16 spontaneous menopausal women receiving conjugated equine estrogen, 0.625 mg/day plus medroxyprogesteron acetate, 5mg/day (CEE + MPA) for 2.4 +/- 1.0 years and Group C: 15 spontaneous menopausal women receiving tibolone, 2.5mg/day for 2.4 +/- 1.3 years. Control group consisted of 15 spontaneous menopausal women who never had HRT. RESULTS: Significant differences in terms of DNA damage were observed between Group A and B with controls as mean total comet scores 23.93 +/- 5.84, 19.44 +/- 6.19 and 10.07 +/- 2.40, but no significance (P > 0.05) were detected between Group C and controls as mean total comet scores 12.07 +/- 3.65 and 10.07 +/- 2.40, respectively. CONCLUSION: Reduced DNA damage were observed with tibolone compared to CEE or CEE + MPA therapy. Studies of this approach are needed.