A preliminary study on nonylphenol toxicity in human intestinal epithelial cells.

Nonylphenol (NP) is a common contaminant of aquatic environments known to possess estrogenic properties. Due to its high stability and lipid solubility, it accumulates in fish and it has also been detected in drinking water and vegetables. Consequently, humans are constantly exposed to NP by ingestion of contaminated food and water. Since NP effects on human intestine have poorly been explored, we aimed to characterize toxic effects of NP in an intestinal epithelial cell line (Caco-2) of human origin. We observed that, in the presence of low doses (less of 1 μM) of NP, cell number decreased of about 25% after 24 h and of 40% after 72 h. We also found that a treatment of 24 h with NP caused a reduction of 30% of cells able to enter into S-phase, as revealed by nuclear bromodeoxyuridine incorporation. Instead, we registered an increase of cell apoptosis, as revealed by a TUNEL assay. Finally, we found an increase of GRP78 protein expression which indicates a possible involvement of ER-stress in NPinduced apoptosis, as already reported for other cell models. Our preliminary findings support the hypothesis that chronic exposure to NP may exert a damaging effect at the level of intestinal mucosa, thus possibly affecting its digestive and barrier functions