Cell Biol Toxicol (2011) 27:69–81 DOI 10.1007/s10565-010-9171-5 Sodium fluoride influences the expression of keratins in cultured keratinocytes Euridice Prado & Tilmann Wurtz & Didier Ferbus & El-Hassan Shabana & Nadine Forest & Ariane Berdal Received: 14 December 2009 / Accepted: 8 July 2010 / Published online: 1 August 2010 # The Author(s) 2010. This article is published with open access at Springerlink.com Abstract Epithelia in lung, skin, and kidney are often exposed to fluoride, and tissue damage in lung and kidney due to fluoride is well documented. Neverthe- less, the biological effects of fluoride on epithelia are poorly investigated. In the present study, we report effects of sodium fluoride (NaF) on the differentiation of a human epithelial cell line, HaCaT. These cells may serve as a keratinocyte model, because they express a E. Prado (*) : T. Wurtz : D. Ferbus : E.-H. Shabana : N. Forest : A. Berdal Laboratoire de Physiopathologie oro faciale moléculaire, UMRS 872 Groupe 5, CRC, Université Paris 7, 15, rue de l’Ecole de Médecine, Paris Cedex 75006, France e-mail: euridice.prado@gmail.com E. Prado : T. Wurtz : D. Ferbus : E.-H. Shabana : A. Berdal Centre de Recherche des Cordeliers, Université Pierre et Marie Curie, Paris 6, UMRS 872, Paris 75006, France E. Prado : T. Wurtz : E.-H. Shabana : A. Berdal Université René Descartes, Paris 5, UMRS 872, Paris 75006, France E. Prado : T. Wurtz : D. Ferbus : E.-H. Shabana : A. Berdal INSERM, UMRS 872, Paris 75006, France T. Wurtz : E.-H. Shabana : N. Forest : A. Berdal Université Paris Denis Diderot, Paris 7, Paris 75005, France wide spectrum of keratins (Ks), and they associate into stratified tissue-like arrangements along with changes in their keratin pattern. NaF was added to the culture medium at concentrations of 0.5 and 5 mM. Cell proliferation remained intact, but cell functions were altered at high dose, and HSP70 was induced. Reverse transcription-polymerase chain reaction and Western blotting revealed that keratin (K) 15 mRNA and protein expression, associated with stratification of epithelia, were inhibited. Also, expression of keratins typical for terminal differentiation, K1 and K10, was decreased and so was the expression of the K1/10 regulating enhancer binding protein c/EBP alpha. Stratification of HaCaT cells was abolished at high fluoride dose, as assessed by electron microscopy. The changes in keratin expression were not reversed by withdrawal of fluoride. Taken together, NaF at high dose blocked terminal differenti- ation of HaCaT cells, visible by keratin expression and failing stratification. This effect may disturb tissue formation due to altered cell interactions. Keywords c/EBP alpha . Differentiation keratinocytes . Keratins . Sodium fluoride Abbreviations cDNA Complementary deoxyribonucleic acid FCS Fetal calf serum HRP Horseradish phosphate Igs Immunoglobulins IgG Immunoglobulin G