title: Mechanism of pigmentation by minocycline in murine B16 melanoma cells.
abstract: Long-term treatment with minocycline is known to induce pigmentation or discoloration in tissues but how remains unclear. We investigated the mechanism of pigmentation using B16 melanoma cells. First, we confirmed that intracellular melanin levels increased on minocycline treatment. Then, using the reverse transcriptase-polymerase chain reaction (RT-PCR), we found the expression of mRNA of tyrosinase, tyrosinase-related protein (TRP)-1 and TRP-2, to also be significantly increased by treatment with minocycline at 5 µg/ml for 72 h. These results suggest that the minocycline-induced stimulation of melanogenesis occurs at the transcriptional level. Western-blotting revealed slight phosphorylation of extracellular signal-regulated kinase (ERK) 30-60 min after the minocycline treatment. The mitogen-activated protein kinase kinase 1/2 (MEK1/2) inhibitor U0126 and the p38 inhibitor SB203580 were used to examine the signaling pathway associated with the mRNA expression of tyrosinase, TRP-1, or TRP-2 when B16 melanoma cells were treated with minocycline. The SB203580 inhibited the mRNA expression of tyrosinase and TRP-1, suggesting the minocycline-induced melanogensis occurred via a p38 signaling pathway.
authors.affiliation: Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda, Chiba, Japan.
authors.forename: Emi
authors.initials: E
authors.lastname: Sato
authors.forename: Mitsutoshi
authors.initials: M
authors.lastname: Tsukimoto
authors.forename: Noriko
authors.initials: N
authors.lastname: Shimura
authors.forename: Akira
authors.initials: A
authors.lastname: Awaya
authors.forename: Shuji
authors.initials: S
authors.lastname: Kojima
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000009:adverse effects*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D007370:Interferon Type I / Q000378:metabolism; D019746:Intramolecular Oxidoreductases / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000502:physiology; D008543:Melanins / Q000378:metabolism*; D008546:Melanoma, Experimental / Q000378:metabolism*; D051379:Mice; D008911:Minocycline / Q000009:adverse effects*; D014442:Monophenol Monooxygenase / Q000378:metabolism; D010858:Pigmentation / Q000187:drug effects*; D011257:Pregnancy Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
chemical_list: D000900:Anti-Bacterial Agents; D007370:Interferon Type I; D008543:Melanins; D011257:Pregnancy Proteins; C020947:interferon tau; D014442:Monophenol Monooxygenase; D048049:Extracellular Signal-Regulated MAP Kinases; D019746:Intramolecular Oxidoreductases; C042501:dopachrome isomerase; D008911:Minocycline