Characterization of two novel small molecules targeting melanocyte development in zebrafish embryogenesis
ABSTRACT Melanocytes are pigment cells that are closely associated with many skin disorders, such as vitiligo, piebaldism, Waardenburg syndrome, and the deadliest skin cancer, melanoma. Through studies of model organisms, the genetic regulatory network of melanocyte development during embryogenesis has been well established. This network also seems to be shared with adult melanocyte regeneration and melanoma formation. To identify chemical regulators of melanocyte development and homeostasis, we screened a small-molecule library of 6000 compounds using zebrafish embryos and identified five novel compounds that inhibited pigmentation. Here we report characterization of two compounds, 12G9 and 36E9, which disrupted melanocyte development. TUNEL assay indicated that these two compounds induced apoptosis of melanocytes. Furthermore, compound 12G9 specifically inhibited the viability of mammalian melanoma cells in vitro. These two compounds should be useful as chemical biology tools to study melanocytes and could serve as drug candidates against melanocyte-related diseases.
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ABSTRACT: Cuscuta chinensis seeds have traditionally been used to treat freckles and melasma in Asia, although recent reports have revealed that Semen cuscutae is a promoter of melanogenesis. The present study aims to investigate the mechanism of this opposite effect of Semen cuscutae on melanogenesis. In accordance with traditional usage, the water fraction and the ethanol fraction from Semen cuscutae (WFSC/EFSC) were extracted to determine the herbal effects by examining The activity of mushroom tyrosinase, cellular melanin contents, tyrosinase activity assay, quantitative-reverse transcription polymerase chain reaction (qRT-PCR), and Western blot analysis for tyrosinase in B16F10 mouse melanoma cells. The melanocyte phenotypes of zebrafish larvae were observed while the in vivo melanin contents and tyrosinase activity were determined. The activity of mushroom tyrosinase assay shown that WFSC was an uncompetitive inhibitor of mushroom tyrosinase, while EFSC indicated dose-dependent activation of the mushroom tyrosinase activity. The WFSC markedly inhibited 3-isobutyl-1-methylxanthine (IBMX)-stimulated melanin synthesis and tyrosinase activity in vitro. However, the EFSC had an accelerant role in melanin synthesis and tyosinase activity. Neither fraction had any effect on the IBMX-induced expression of tyrosinase protein or mRNA. The WFSC strongly inhibited melanin synthesis and cellular tyrosinase activity in vivo. Furthermore, with the function of WFSC at a higher concentration, a punctate melanocyte pattern appeared that was similar to the pattern induced by arbutin or mequinol (MQ). The EFSC had no effect on the melanocytes of zebrafish larvae. It was discovered that WFSC did not show a stable inhibitory effect until it was extracted 1 month later. These results suggest that the opposite effects of Cuscuta chinensis seeds were caused by the extraction methods and that time has an important role in the effect of WFSC. Both WFSC and EFSC significant influence melanogenesis by regulating enzymatic activity of tyrosinase. In addition, the data indicate that wildtype (WT) zebrafish may be an ideal model for testing inhibitors of melanogenesis from clinically active herbs.Journal of ethnopharmacology 04/2014; DOI:10.1016/j.jep.2014.04.016 · 2.94 Impact Factor
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ABSTRACT: Fish melanoma models are increasingly used in studies of both spontaneous and induced melanoma formation. The melanoma Xiphophorus model was the first genetic model of melanoma available to researchers since the 1920s (Klin Wochenschrift 7:1561–1562, 1928; Z Indukt Abstammungs 44:253–257, 1927). Recently, transgenesis has been used to develop zebrafish and medaka models for melanoma research (Methods Mol Biol 461:521–539, 2008). These models are now starting to produce a wealth of novel information on the genetics of melanoma (including somatic mutations), signaling pathways and molecular mechanisms, immune responses, and determinants of metastasis. Moreover, the models are extremely well suited for drug/small-molecule screens aimed at discovering new therapeutic strategies in general treatment and personalized medicine and for the study of cancer-immune cell interactions. This review provides a summary of current and prospective studies in fish models of melanoma and pinpoints the translational potentials of melanoma models in fish.06/2014; 2(2). DOI:10.1007/s40139-014-0043-1