Modulations of DNMT1 and HDAC1 are involved in the OTA-induced cytotoxicity and apoptosis in vitro

Ochratoxin A (OTA) as a fungal metabolite is reported to induce cytotoxicity and apoptosis through the mechanism of oxidative stress. Oxidative stress could induce the epigenetic enzymes modifications. However, whether epigenetic enzymes modifications are involved in OTA-induced cytotoxicity and apoptosis has not been reported until now. Therefore, the objectives of this study were to verify OTA-induced cytotoxicity and apoptosis and to investigate the potential role of epigenetic enzymes in OTA-induced cytotoxicity and apoptosis in PK15 cells. The results demonstrated that OTA at 4 μg/ml treatment for 12 h and 24 h induced cytotoxicity and apoptosis as demonstrated by decreasing cell viability, increasing LDH release, Annexin V/PI staining, Bcl-2/Bax mRNA ratio and apoptotic nuclei in PK15 cells. OTA treatment up-regulated ROS production and down-regulated GSH levels. In addition, OTA treatment activated the epigenetics related enzymes DNA methyltransferase 1 (DNMT1) and Histone deacetylase 1 (HDAC1). Adding DNMT1 inhibitor (5-Aza-2dc) or HDAC1 inhibitor (LBH589) depressed the up-regulation of DNMT1 or HDAC1 expression, the decreases of GSH levels and increases of ROS production induced by OTA, respectively. Furthermore, inhibition of DNMT1 or HDAC1 by their inhibitor reversed the decreases of cell viability and increases of LDH activity and apoptosis induced by OTA, respectively. In conclusion, the observed effects indicate that the critical modulation of DNMT1 and HDAC1 is related to OTA-induced cytotoxicity and apoptosis.