p-Phenylenediamine induces p53-mediated apoptosis in Mardin-Darby canine kidney cells.

The mechanism of toxicity p-phenylenediamine (p-PD), a component of human permanent hair dye and a suspected carcinogen, on the growth of Mardin-Darby canine kidney cells (MDCK) was investigated. With the analysis of flow cytometry, a dose-dependent accumulation of the sub-G1 peak and the G0/G1-phase arrested in cell cycle, and time-dependent induction of apoptosis after staining with Annexin V-Fluorescein and propidium iodide were observed. After the treatment of cells with p-PD, dose dependent DNA fragmentation shown by gel electrophoresis, the reduction of membrane potential (DeltaPsim) by mitochondria membrane depolarization and the increase of the expression of p53 protein in cells, suggested that the effect of p-PD on overall viability and cell numbers is mediated by an increase in apoptosis.