Gene expression profiling of hair-dying agent, para-phenylenediamine, in human keratinocytes (HaCaT) cells

Abstract

Para-phenylenediamine (PPD) is widely used in a variety of products, including hair dyes. Sensitization to PPD is a well-known cause of allergic contact dermatitis. However, the molecular mechanism of PPD-induced cellular toxicity remains unclear. We performed a genome-wide analysis of transcriptional responses of human HaCaT keratinocytes to an IC20 dose of PPD (60 mu M). PPD downregulated the expression of 650 genes and upregulated the expression of 854 genes in the keratinocytes. PPD-responsive genes were involved in inflammatory responses, responses to oxidative stress, Toll-like receptor signaling, and metabolism of xenobiotics by cytochrome P450. Our results indicate that changes in gene expression are associated with PPD-induced skin toxicity, and the genes identified may be promising biomarkers of PPD-induced skin toxicity. Possible roles of the responsive genes and related pathways in PPD-induced cellular responses are discussed. This study helps to elucidate cellular changes in transcriptional regulation in response to PPD exposure.