Hydroquinone is used as a skin-lightening agent, it is also present in different chemical products and cigarette smoke. It is believed to inhibit melanin production in melanocytes by inhibiting the key enzyme tyrosinase. In the present study, we show that hydroquinone had severe effects on microtubules and actin filaments in cultured Xenopus laevis melanophores as studied by immunohistochemistry. It affected the intracellular transport of melanosomes, induced bundling of microtubules and disassembly of actin filaments at 10 and 50？μM, and at 100？μM proper adhesion to the substrate was lost. Effects occurred at lower concentrations than what previously has been stated to be cytotoxic, and the results show that tyrosinase is not the only cellular target. The cytoskeleton is of utmost importance for the function of all cells and across species. Our data has therefore to be considered in the discussions about the use of hydroquinone for bleaching of skin. 1. Introduction Hydroquinone (HQ) is a synthetically produced and naturally occurring chemical that is used for example in cosmetics as a skin-lightening agent, as a reagent in photographic developers, and in rubber manufacture [1]. It is also present in significant levels in cigarette smoke [2]. Genomic and proteomic analyses have shown that HQ treatment induces changes in proteins that are involved in for instance oxidative stress, focal adhesion, cellular signalling, and cytoskeleton reconstruction [1–3]. As a skin-lightening agent, HQ is believed to act by inhibition of the enzyme tyrosinase, thereby reducing the conversion of dihydroxybenzoic acid (DOPA) to melanin [4, 5]. Administration of HQ induces reduced pigmentation in mammals [6] and has been suggested to have a selective melanotoxic action. Using melanocytes and nonmelanotic cells, it has been demonstrated that sensitivity to the cytotoxic effects of HQ is associated with the presence of tyrosinase activity [7], and cytotoxicity is increased when cells are exposed to UVA radiation [8]. Uncontrolled use of HQ-containing bleaching products has resulted in an epidemic of postinflammatory hyperpigmentation (exogenous ochronosis) in South Africa [9, 10]. Due to the toxicological side effects the use of HQ in cosmetics has been banned in the European Union [11], but it is still allowed in many countries. In order to gain further insight in potential mechanism(s) of action and cellular effects of HQ, we have used immortalized melanophores from the African clawed frog, Xenopus laevis. Melanophores derive from the neural crest and are cells specialized
References
[1]
X. Li, Z. Zhuang, J. Liu, H. Huang, Q. Wei, and X. Yang, “Proteomic analysis to identify the cellular responses induced by hydroquinone in human embryonic lung fibroblasts,” Toxicology Mechanisms and Methods, vol. 16, no. 1, pp. 1–6, 2006.
[2]
O. Alcazar, A. M. Hawkridge, T. S. Collier et al., “Proteomics characterization of cell membrane blebs in human retinal pigment epithelium cells,” Molecular and Cellular Proteomics, vol. 8, no. 10, pp. 2201–2211, 2009.
[3]
S. N. Sarma, Y.-J. Kim, and J.-C. Ryu, “Differential gene expression profiles of human leukemia cell lines exposed to benzene and its metabolites,” Environmental Toxicology and Pharmacology, vol. 32, no. 2, pp. 285–295, 2011.
[4]
B. Kasraee, “Peroxidase-mediated mechanisms are involved in the melanocytotoxic and melanogenesis-inhibiting effects of chemical agents,” Dermatology, vol. 205, no. 4, pp. 329–339, 2002.
[5]
Y. M. Olumide, A. O. Akinkugbe, D. Altraide et al., “Complications of chronic use of skin lightening cosmetics,” International Journal of Dermatology, vol. 47, no. 4, pp. 344–353, 2008.
[6]
T.-J. Yoon, T. C. Lei, Y. Yamaguchi, J. Batzer, R. Wolber, and V. J. Hearing, “Reconstituted 3-dimensional human skin of various ethnic origins as an in vitro model for studies of pigmentation,” Analytical Biochemistry, vol. 318, no. 2, pp. 260–269, 2003.
[7]
C. J. Smith, K. B. O'Hare, and J. C. Allen, “Selective cytotoxicity of hydroquinone for melanocyte-derived cells is mediated by tyrosinase activity but independent of melanin content,” Pigment Cell Research, vol. 1, no. 6, pp. 386–389, 1988.
[8]
Z. M. Hu, Q. Zhou, T.-C. Lei, S.-F. Ding, and S.-H. Xu, “Effects of hydroquinone and its glucoside derivatives on melanogenesis and antioxidation: biosafety as skin whitening agents,” Journal of Dermatological Science, vol. 55, no. 3, pp. 179–184, 2009.
[9]
P. G. Engasser and H. I. Maibach, “Cosmetics and dermatology: bleaching creams,” Journal of the American Academy of Dermatology, vol. 5, no. 2, pp. 143–147, 1981.
[10]
P. R. Hull and P. R. Procter, “The melanocyte: an essential link in hydroquinone-induced ochronosis,” Journal of the American Academy of Dermatology, vol. 22, no. 3, pp. 529–531, 1990.
[11]
S. Briganti, E. Camera, and M. Picardo, “Chemical and instrumental approaches to treat hyperpigmentation,” Pigment Cell Research, vol. 16, no. 2, pp. 101–110, 2003.
[12]
S. Aspengren, H. N. Sk？ld, and M. Wallin, “Different strategies for color change,” Cellular and Molecular Life Sciences, vol. 66, no. 2, pp. 187–191, 2009.
[13]
S. Aspengren, L. Wielbass, and M. Wallin, “Effects of acrylamide, latrunculin, and nocodazole on intracellular transport and cytoskeletal organization in melanophores,” Cell Motility and the Cytoskeleton, vol. 63, no. 7, pp. 423–436, 2006.
[14]
D. Hedberg and M. Wallin, “Effects of Roundup and glyphosate formulations on intracellular transport, microtubules and actin filaments in Xenopus laevis melanophores,” Toxicology in Vitro, vol. 24, no. 3, pp. 795–802, 2010.
[15]
S. L. Rogers and V. I. Gelfand, “Myosin cooperates with microtubule motors during organelle transport in melanophores,” Current Biology, vol. 8, no. 3, pp. 161–164, 1998.
[16]
S. D. Blystone, “Integrating an integrin; a direct route to actin,” Biochimica et Biophysica Acta, vol. 1692, no. 2-3, pp. 47–54, 2004.
[17]
M. Wallin and B. Hartley-Asp, “Effects of potential aneuploidy inducing agents on microtubule assembly in vitro,” Mutation Research, vol. 287, no. 1, pp. 17–22, 1993.
[18]
Y. J. Kim, H. D. Woo, B. M. Kim et al., “Risk assessment of hydroquinone: differential responses of cell growth and lethality correlated to hydroquinone concentration,” Journal of Toxicology and Environmental Health: Part A, vol. 72, no. 21-22, pp. 1272–1278, 2009.
[19]
N. Strunnikova, C. Zhang, D. Teichberg et al., “Survival of retinal pigment epithelium after exposure to prolonged oxidative injury: a detailed gene expression and cellular analysis,” Investigative Ophthalmology and Visual Science, vol. 45, no. 10, pp. 3767–3777, 2004.
[20]
M. Pons, S. W. Cousins, K. G. Csaky, G. Striker, and M. E. Marin-Casta？o, “Cigarette smoke-related hydroquinone induces filamentous actin reorganization and heat shock protein 27 phosphorylation through p38 and extracellular signal-regulated kinase 1/2 in retinal pigment epithelium: implications for age-related macular degeneration,” American Journal of Pathology, vol. 177, no. 3, pp. 1198–1213, 2010.
[21]
K. Kageyama, Y. Onoyama, and E. Kano, “Effects of methyl mercuric chloride and sulfhydryl inhibitors on phospholipid synthetic activity of lymphocytes,” Journal of Applied Toxicology, vol. 6, no. 1, pp. 49–53, 1986.
[22]
D.-X. Shen, X. Shi, J.-L. Fu, Y.-M. Zhang, and Z.-C. Zhou, “The role of thiol reduction in hydroquinone-induced apoptosis in HEK293 cells,” Chemico-Biological Interactions, vol. 145, no. 2, pp. 225–233, 2003.
[23]
C. H. Martenson, A. Odom, M. P. Sheetz, and D. G. Graham, “The effect of acrylamide and other sulfhydryl alkylators on the ability of dynein and kinesin to translocate microtubules in vitro,” Toxicology and Applied Pharmacology, vol. 133, no. 1, pp. 73–81, 1995.
[24]
W. Chavin, “Effects of hydroquinone and of the hypophysectomy upon the pigment cells of black goldfish,” Journal of Pharmacology and Experimental Therapeutics, vol. 142, pp. 275–290, 1963.
[25]
F. Hu, “The influence of certain hormones and chemicals on mammalian pigment cells,” Journal of Investigative Dermatology, vol. 46, no. 1, pp. 117–124, 1966.
[26]
S. Aspengren, D. Hedberg, and M. Wallin, “Studies of pigment transfer between Xenopus laevis melanophores and fibroblasts in vitro and in vivo,” Pigment Cell Research, vol. 19, no. 2, pp. 136–145, 2006.
[27]
J. T. Bagnara, “Comparative anatomy and physiology of pigment cells in nonmammalian tissues,” in The Pigmentary System, pp. 9–40, Oxford University Press, Oxford, UK, 1998.
[28]
R. E. Boissy, “Melanosome transfer to and translocation in the keratinocyte,” Experimental Dermatology, vol. 12, no. 2, pp. 5–12, 2003.
[29]
M. E. Hadley and W. C. Quevedo, “The role of epidermal melanocytes in adaptive color changes in amphibians,” in Advances in Biology of Skin, pp. 337–358, Pergamon Press, Glasgow, UK, 1967.
[30]
K. Jimbow and S. Sugiyama, “Melanosomal translocation and transfer,” in The Pigmentary System, pp. 107–114, Oxford University Press, Oxford, UK, 1998.
[31]
M. Seiberg, “Keratinocyte-melanocyte interactions during melanosome transfer,” Pigment Cell Research, vol. 14, no. 4, pp. 236–242, 2001.
[32]
R. M. Halder and G. M. Richards, “Topical agents used in the management of hyperpigmentation,” Skin Therapy Letter, vol. 9, no. 6, pp. 1–3, 2004.
[33]
A. P. DeCaprio, “The toxicology of hydroquinone—relevance to occupational and environmental exposure,” Critical Reviews in Toxicology, vol. 29, no. 3, pp. 283–330, 1999.
[34]
D. A. Dickinson, D. R. Moellering, K. E. Iles et al., “Cytoprotection against oxidative stress and the regulation of glutathione synthesis,” Biological Chemistry, vol. 384, no. 4, pp. 527–537, 2003.
[35]
J. L. Bolognia, S. A. Sodi, M. P. Osber, and J. M. Pawelek, “Enhancement of the depigmenting effect of hydroquinone by cystamine and buthionine sulfoximine,” British Journal of Dermatology, vol. 133, no. 3, pp. 349–357, 1995.
[36]
G. Bellomo and F. Mirabelli, “Oxidative stress and cytoskeletal alterations,” Annals of the New York Academy of Sciences, vol. 663, pp. 97–109, 1992.
