Inhibition of Melanogenesis by the Antidiabetic Metformin

• Published in: Journal of investigative dermatology Vol. 134; no. 10; pp. 2589 - 2597
• Main Authors: Lehraiki, Abdelali, Abbe, Patricia, Cerezo, Michael, Rouaud, Florian, Regazzetti, Claire, Chignon-Sicard, Bérengère, Passeron, Thierry, Bertolotto, Corine, Ballotti, Robert, Rocchi, Stéphane
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.10.2014; Elsevier Limited; Nature Publishing Group
• Subjects: Animals; Biopsy; Cancer; Cell Line, Tumor; Cell Proliferation; Cells, Cultured; Cyclic AMP - metabolism; Dose-Response Relationship, Drug; Humans; Hypoglycemic Agents - pharmacology; In Vitro Techniques; Life Sciences; Melanins - metabolism; Melanocytes - drug effects; Melanocytes - metabolism; Melanocytes - pathology; Melanoma - metabolism; Melanoma - pathology; Metformin - pharmacology; Mice; Mice, Inbred C57BL; Microphthalmia-Associated Transcription Factor - metabolism; Skin - drug effects; Skin - metabolism; Skin - pathology; Skin Neoplasms - metabolism; Skin Neoplasms - pathology; Skin Pigmentation - drug effects; Time Factors
• ISSN: 0022-202X; 1523-1747
• DOI: 10.1038/jid.2014.202

Several reports have demonstrated the inhibitory effect of metformin, a widely used drug in the treatment of type 2 diabetes, on the proliferation of many cancers including melanoma. Recently, it has been shown that metformin is able to modulate the cAMP level in the liver. As cAMP has a crucial role in melanin synthesis and skin pigmentation, we investigated the effect of metformin on melanogenesis both in vitro and in vivo. We showed that metformin led to reduced melanin content in melanoma cells and in normal human melanocytes by decreasing cAMP accumulation and cAMP-responsive element–binding protein phosphorylation. This inhibitory effect is correlated with decreased expression of master genes of melanogenesis, microphthalmia-associated transcription factor, tyrosinase, dopachrome tautomerase, and tyrosinase-related protein 1. Furthermore, we demonstrated that the antimelanogenic effect of metformin is independent of the AMPK pathway. Interestingly, topical application of metformin induced tail whitening in mice. Finally, we confirmed the antimelanogenic effect of metformin on reconstituted human epidermis and on human skin biopsies. These data emphasize the depigmenting effect of metformin and suggest a clinical strategy for using metformin in the topical treatment of hyperpigmentation disorders.