Proteomic analysis to identify the cellular responses induced by hydroquinone in human embryonic lung fibroblasts

Hydroquinone (HQ), a major metabolite of benzene, is used widely as a reagent in photographic developers, as an antioxidant in the manufacture of rubber, as a polymerization inhibitor for acrylic and vinyl acetate monomers, and in cosmetic products as a skin-lightening agent. But the mechanism of its effect on human cells is far from clear. In the present work, we studied the cellular response induced by HQ using proteomic approaches. Human embryonic lung fibroblasts (HLFs) were treated with 100 mu M HQ for 24 h. This dose of HQ was found in assays to significantly decrease cell viability. After treatment, two-dimensional electrophoresis was performed using the Amersham Bioscience 2DE system following the manufacturer's instructions. Proteins were visualized by staining with colloidal coomassie blue. Fifteen protein spots showed significant changes after HQ treatment. Eleven protein spots were identified by peptide mass fingerprinting using MALDI-TOF or by peptide sequence tagging using MALDI-TOF-TOF. Among them are transaldolase, growth factor receptor-bound protein 2, mutant beta -actin, gamma -actin, Lasp-1, TAR DNA-binding protein, and a protein similar to neural precursor cell-expressed protein. These include proteins involved in oxidative stress, cellular signaling, RNA splicing, and cytoskeleton reconstruction. Most of their involvements in the cellular responses to HQ have not been reported. Therefore, our findings may offer new insights into the mechanisms of HQ cytotoxicity and these proteins may serve as new biomarkers for detecting exposure of human populations to HQ. It is suggested that proteomic approaches may provide new strategies to evaluate the toxicity of xenobiotics.