Inhibitory effect of Phalaenopsis orchid extract on WNT1-induced immature melanocyte precursor differentiation in a novel in vitro solar lentigo model

• Published in: Bioscience, biotechnology, and biochemistry Vol. 80; no. 7; pp. 1321 - 1326
• Main Authors: Yamada, Takaaki, Hasegawa, Seiji, Inoue, Yu, Kunita, Mayumi, Ohsumi, Kazuhisa, Sakaida, Tsutomu, Yashiro, Youichi, Nakata, Satoru
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis 01.07.2016
• Subjects: Antigens, Surface - genetics; Antigens, Surface - metabolism; Cell Differentiation - drug effects; Cell Differentiation - radiation effects; Cell Line, Tumor; Cell Survival - drug effects; Cell Survival - radiation effects; Coculture Techniques; differentiation; Gene Expression Regulation; Humans; Keratinocytes - cytology; Keratinocytes - drug effects; Keratinocytes - metabolism; Keratinocytes - radiation effects; Lentigo - prevention & control; melanocyte stem cell; Melanocytes - cytology; Melanocytes - drug effects; Melanocytes - metabolism; Melanocytes - radiation effects; Models, Biological; Orchidaceae - chemistry; pigmentation; Plant Extracts - chemistry; Protective Agents - isolation & purification; Protective Agents - pharmacology; Signal Transduction; solar lentigo; Ultraviolet Rays - adverse effects; Wnt1 Protein - antagonists & inhibitors; Wnt1 Protein - genetics; Wnt1 Protein - metabolism; pigmentation; differentiation; solar lentigo; melanocyte stem cell
• ISSN: 0916-8451; 1347-6947
• DOI: 10.1080/09168451.2016.1153952

Recently, it has been reported that increased expression of WNT1 accelerates the differentiation of melanocyte stem cells (McSCs) in solar lentigines (SLs), hyperpigmented maculae commonly seen on sun-exposed areas of the skin. In this study, to establish an in vitro SL model, human epidermal squamous carcinoma cell line HSC-1, which expresses higher levels of WNT1 than normal human epidermal keratinocytes, was co-cultured with early passage normal human epidermal melanocytes (NHEMs) as an in vitro McSC model. As a result, mRNA expression levels of melanocyte differentiation-related genes MITF and TYR in NHEMs were significantly increased by co-culturing with HSC-1 cells. Furthermore, Phalaenopsis orchid extract (Phex) inhibited McSCs differentiation by suppressing WNT1 expression via down-regulation of DLX2, a transcriptional activator of WNT1, in HSC-1 cells. Therefore, our finding suggested that extracts such as Phex, which suppresses WNT1 expression, may be useful as a novel treatment of SLs. Phalaenopsis orchid extract (Phex) suppressed McSC differentiation (A) by inhibiting WNT1 expression via down-regulation of DLX2 (B).