Neural stem cells inhibit melanin production by activation of Wnt inhibitors

Insik Hwang, Ju Hwang Park, Hang Soo Park, Kyung Ah Choi, Ki Cheon Seol, Seung Ick Oh, Seongman Kang, Sunghoi Hong

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)


Background: Melanin for skin pigmentation is synthesized from tyrosine via an enzymatic cascade that is controlled by tyrosinase (TYR), tyrosinase-related protein 1 (TRP1), and dopachrome tautomerase/tyrosinase related protein 2 (Dct/TRP2), which are the targets of microphthalmia-associated transcription factor (MITF). MITF is a master regulator of pigmentation and a target of β-catenin in Wnt/β-catenin signaling during melanocyte differentiation. Stem cells have been used in skin pigmentation studies, but the mechanisms were not determined for the conditioned medium (CM)-mediated effects. Objectives: In this study, the inhibition and mechanisms of melanin synthesis were elucidated in B16 melanoma cells and UV-B irradiated C57/BL-6 mice that were treated with human neural stem cell-conditioned medium (NSC-CM). Methods: B16-F10 melanoma cells (1.5×104cells/well) and the shaved dorsal skin of mice were pretreated with various amount (5, 10, 20, 50, and 100%) of NSC-CM. Melanin contents and TYR activity were measured by a Spectramax spectrophotometer. The expression of TYR, TRP1, Dct/TRP2, MITF, β-catenin and Wnt inhibitors were evaluated by RT-PCR and western blot. The dorsal skin samples were analyzed by immunofluorescence with various antibodies and compared with that control of tissues. Results: Marked decreases were evident in melanin content and TYR, TRP1, DCT/TRP2, MITF, and β-catenin expression in B16 cells and C57/BL-6 mice. NSC-CM negatively regulated Wnt/β-catenin signaling by decreasing the expression of β-catenin protein, which resulted from robust expression of Wnt inhibitors Dickkopf-1 (DKK1) and secreted frizzled-related protein 2 (sFRP2). Conclusions: These results demonstrate that NSC-CM suppresses melanin production in vitro and in vivo, suggesting that factors in NSC-CM may play an important role in deregulation of epidermal melanogenesis.

Original languageEnglish
Pages (from-to)274-283
Number of pages10
JournalJournal of Dermatological Science
Issue number3
Publication statusPublished - 2013 Dec

Bibliographical note

Funding Information:
This work was supported by grants from Korea University ( K1131492 ), the National Research Foundation of Korea (NRF) ( 20100020349 and 2012M3A9C6050131 ) and the Korea Ministry of Health and Welfare ( A120392 ).


  • MITF
  • Melanin
  • Neural stem cell-conditioned medium
  • Tyrosinase
  • Wnt inhibitors

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Dermatology


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