DNA methylation analysis in rat kidney epithelial cells exposed to 3-MCPD and glycidol

Abstract

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 48 mM and 41.39 mM, whereas IC₅₀ value of glycidol was 1.67 mM and 1.13 mM by MTT and NRU test, respectively. Decreased global DNA methylation at the concentrations of 100 μM and 1000 μM for 3-MCPD and 100 μM and 500 μM 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.

Keywords:

• 3-MCPD
• glycidol
• DNA methylation
• cytotoxicity
• NRK-52 cells

Acknowledgements

This work was supported partly by Scientific Research Projects Coordination Unit of Istanbul University (Project numbers: UDP-45004, ONAP-37505; BYP-46016) and TUBITAK (Project no. 2210-C/2014–2, Grant for Mine Senyildiz).

Declaration of interest

The authors report no declarations of interest. The authors alone are responsible for the content and writing of the paper.