Para-phenylenediamine induced DNA damage and apoptosis through oxidative stress and enhanced caspase-8 and -9 activities in Mardin-Darby canine kidney cells.

Para-phenylenediamine (p-PD), a suspected carcinogen, is a component of permanent hair dyes. In this study we examined the mechanism of cytotoxicity and genotoxicity in Mardin-Darby canine kidney cells (MDCK)-treated with p-PD. Our results showed that p-PD decreased cell viability in a dose- and time-dependent manner. In addition, p-PD induced DNA damage was confirmed by the comet and TUNEL assays. Pre-treatment of MDCK cells with antioxidants vitamin C or E significantly inhibited p-PD induced cytotoxicity and reactive oxygen species (ROS) generation. Furthermore, p-PD induced apoptosis through activated initiator caspase-8 and -9, and effector caspase-3/7. Based on these results, we suggested that p-PD induce apoptosis which was mediated with caspase-8, caspase-9 and caspase-3/7 activation via the involvement of ROS.