http://hdl.handle.net/20.500.12627/208 2026-05-01T03:38:43Z 2026-05-01T03:38:43Z Ozden, Sibel Mally, Angela Kara, Neslihan Turgut Chen, Tao Alpertunga, Buket Chipman, J. Kevin Durasi, Ilknur Melis Sezerman, Osman Uğur Demirel, Goksun http://hdl.handle.net/20.500.12627/1086 2020-09-29T08:04:54Z 2015-01-01T00:00:00Z

Assessment of global and gene-specific DNA methylation in rat liver and kidney in response to non-genotoxic carcinogen exposure Ozden, Sibel; Mally, Angela; Kara, Neslihan Turgut; Chen, Tao; Alpertunga, Buket; Chipman, J. Kevin; Durasi, Ilknur Melis; Sezerman, Osman Uğur; Demirel, Goksun Altered expression of tumor suppressor genes and oncogenes, which is regulated in part at the level of DNA methylation, is an important event involved in non-genotoxic carcinogenesis. This may serve as a marker for early detection of non-genotoxic carcinogens. Therefore, we evaluated the effects of non-genotoxic hepatocarcinogens, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), hexachlorobenzene (HCB), methapyrilene (MPY) and male rat kidney carcinogens, d-limonene, p-dichlorobenzene (DCB), chloroform and ochratoxin A (OTA) on global and CpG island promoter methylation in their respective target tissues in rats. No significant dose-related effects on global DNA hypomethylation were observed in tissues of rats compared to vehicle controls using LC-MS/MS in response to short-term non-genotoxic carcinogen exposure. Initial experiments investigating gene-specific methylation using methylation-specific PCR and bisulfite sequencing, revealed partial methylation of p16 in the liver of rats treated with HCB and TCDD. However, no treatment related effects on the methylation status of Cx32, e-cadherin, VHL, c-myc, Igfbp2, and p15 were observed. We therefore applied genome-wide DNA methylation analysis using methylated DNA immunoprecipitation combined with microarrays to identify alterations in gene-specific methylation. Under the conditions of our study, some genes were differentially methylated in response to MPY and TCDD, whereas d-limonene, DCB and chloroform did not induce any methylation changes. 90-day OTA treatment revealed enrichment of several categories of genes important in protein kinase activity and mTOR cell signaling process which are related to OTA nephrocarcinogenicity. (C) 2015 Elsevier Inc. All rights reserved.

2015-01-01T00:00:00Z Ozcagli, Eren Alpertunga, Buket Tsatsakis, Aristidis M. Fenga, Concettina Tsıtsımpıkou, Christina Wilks, Martin F. Berktas, Mehmet http://hdl.handle.net/20.500.12627/1085 2020-09-29T08:04:54Z 2016-01-01T00:00:00Z

Effects of 3-monochloropropane-1,2-diol (3-MCPD) and its metabolites on DNA damage and repair under in vitro conditions Ozcagli, Eren; Alpertunga, Buket; Tsatsakis, Aristidis M.; Fenga, Concettina; Tsıtsımpıkou, Christina; Wilks, Martin F.; Berktas, Mehmet 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 - 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 mu g/mL. These findings provide further insights into the mechanisms underlying the in vitro genotoxic potential of 3-MCPD and metabolites. (C) 2016 Elsevier Ltd. All rights reserved.

2016-01-01T00:00:00Z Ozden, Sibel Senyildiz, Mine Alpertunga, Büket http://hdl.handle.net/20.500.12627/1084 2020-09-29T08:04:54Z 2017-01-01T00:00:00Z

DNA methylation analysis in rat kidney epithelial cells exposed to 3-MCPD and glycidol Ozden, Sibel; Senyildiz, Mine; Alpertunga, Büket 3-Monochloropropane-1,2-diol (3-MCPD) is a well-known food processing contaminant that has been regarded as a rat carcinogen, which is known to induce Leydig-cell and mammary gland tumors in males, as well as kidney tumors in both genders. 3-MCPD is highly suspected to be a non-genotoxic carcinogen. 2,3-Epoxy-1-propanol (glycidol) can be formed via dehalogenation from 3-MCPD. We aimed to investigate the cytotoxic effects of 3-MCPD and glycidol, then to demonstrate the possible epigenetic mechanisms with global and gene-specific DNA methylation in rat kidney epithelial cells (NRK-52E). IC50 value of 3-MCPD was determined as 48mM and 41.39 mM, whereas IC50 value of glycidol was 1.67mM and 1.13mM by MTT and NRU test, respectively. Decreased global DNA methylation at the concentrations of 100 mM and 1000 mu M for 3-MCPD and 100 mu M and 500 mu M for glycidol were observed after 48 h exposure by using 5-methylcytosine (5-mC) ELISA kit. Methylation changes were detected in promoter regions of c-myc and Rassf1a in 3-MCPD and glycidol treated NRK-52E cells by using methylation-specific PCR (MSP), whereas changes on gene expression of c-myc and Rassf1a were observed by using real-time PCR. However, e-cadherin, p16, VHL and p15 genes were unmethylated in their CpG promoter regions in response to treatment with 3-MCPD and glycidol. Alterations in DNA methylation might be key events in the toxicity of 3-MCPD and glycidol. Alterations in DNA methylation might be key events in the toxicity of 3-MCPD and glycidol.

2017-01-01T00:00:00Z