Expression Levels Of Tyrosinase Research Articles

Tyrosinase regulates the motility of human melanoma cell line A375 through its hydroxylase enzymatic activity

Melanoma, originating from melanocytes, is a highly aggressive tumor. Tyrosinase is involved in melanin production in melanocytes, and its overexpression is noted in malignant melanomas. However, the role of tyrosinase in melanomas remains unclear. Therefore, this study aimed to evaluate the potential functions of tyrosinase in the human melanoma cell line A375. The expression level of tyrosinase in A375 cells was undetectable. However, markedly increased expression level was observed in the mouse melanoma cell line B16F10 and the human melanoma cell line WM266-4. Subsequently, we investigated the effect of ectopic tyrosinase expression on A375 cell motility using wound-healing assay. The overexpression of tyrosinase resulted in enhanced cell migration in both stable and transient tyrosinase expression cells. The levels of filamentous actin were decreased in tyrosinase-expressing A375 cells, suggesting that tyrosinase regulates cell motility by modulating actin polymerization. Histidine residues in tyrosinase are important for its enzymatic activity for synthesizing melanin. Substitution of these histidine residues to alanine residues mitigated the promotion of tyrosinase-induced A375 cell metastasis. Furthermore, melanin treatment enhanced A375 cell metastasis and phosphorylation of Cofilin. Thus, our findings suggest that tyrosinase increases the migration of A375 cells by regulating actin polymerization through its enzymatic activity.

Maltol has anti-cancer effects via modulating PD-L1 signaling pathway in B16F10 cells.

Introduction: Among skin cancers, melanoma has a high mortality rate. Recent advances in immunotherapy, particularly through immune checkpoint modulation, have improved the clinical treatment of melanoma. Maltol has various bioactivities, including anti-oxidant and anti-inflammatory properties, but the anti-melanoma property of maltol remains underexplored. The aim of this work is to explore the anti-melanoma potential of maltol through regulating immune checkpoints. Methods: The immune checkpoint PD-L1 was analyzed using qPCR, immunoblots, and immunofluorescence. Melanoma sensitivity towards T cells was investigated via cytotoxicity, cell viability, and IL-2 assays employing CTLL-2 cells. Results: Maltol was found to reduce melanin contents, tyrosinase activity, and expression levels of tyrosinase and tyrosinase-related protein 1. Additionally, maltol suppressed the proliferative capacity of B16F10 and induced cell cycle arrest. Maltol increased apoptotic rates by elevating cleaved caspase-3 and PARP. The co-treatment with maltol and cisplatin revealed a synergistic effect on inhibiting growth and promoting apoptosis. Maltol suppressed IFN-γ-induced PD-L1 and cisplatin-upregulated PD-L1 by attenuating STAT1 phosphorylation, thereby enhancing cisplatin's cytotoxicity against B16F10. Maltol augmented sensitivity to CTLL-2 cell-regulated melanoma destruction, leading to an increase in IL-2 production. Discussion: These findings demonstrate that maltol restricts melanoma growth through the downregulation of PD-L1 and elicits T cell-mediated anti-cancer responses, overcoming PD-L1-mediated immunotherapy resistance of cisplatin. Therefore, maltol can be considered as an effective therapeutic agent against melanoma.

Hydrolyzed Conchiolin Protein (HCP) Extracted from Pearls Antagonizes both ET-1 and α-MSH for Skin Whitening.

Pearl powder is a famous traditional Chinese medicine that has a long history in treating palpitations, insomnia, convulsions, epilepsy, ulcers, and skin lightining. Recently, several studies have demonstrated the effects of pearl extracts on protection of ultraviolet A (UVA) induced irritation on human skin fibroblasts and inhibition of melanin genesis on B16F10 mouse melanoma cells. To further explore the effect we focused on the whitening efficacy of pearl hydrolyzed conchiolin protein (HCP) on human melanoma MNT-1 cells under the irritation of alpha-melanocyte-stimulating hormone (α-MSH) or endothelin 1 (ET-1) to evaluate the intracellular tyrosinase and melanin contents, as well as the expression levels of tyrosinase (TYR), tyrosinase related protein 1 (TRP-1), and dopachrome tautomerase (DCT) genes and related proteins. We found that HCP could decrease the intracellular melanin content by reducing the activity of intracellular tyrosinase and inhibiting the expression of TYR, TRP-1, DCT genes and proteins. At the same time, the effect of HCP on melanosome transfer effect was also investigated in the co-culture system of immortalized human keratinocyte HaCaT cells with MNT-1. The result indicated that HCP could promote the transfer of melanosomes in MNT-1 melanocytes to HaCaT cells, which might accelerate the skin whitening process by quickly transferring and metabolizing melanosomes during keratinocyte differentiation. Further study is needed to explore the mechanism of melanosome transfer with depigmentation.

A Novel Furocoumarin Derivative, 5-((diethylamino)me-13 thyl)-3-phenyl-7H-furo [3,2-g] chromen-7-one Upregulates Melanin Synthesis via the Activation of cAMP/PKA and MAPKs Signal Pathway: In Vitro and In Vivo Study.

Psoralen, a major furocoumarin component of the Fructus Psoralen (FP), in combination with ultraviolet radiation, cures abnormal pigmentation disorder. In a previous study, we synthesized a series of linear furocoumarins with different substituents, out of which 5-((diethylamino)methyl)-3-phenyl-7H-furo [3,2-g] chromen-7-one (encoded as 5D3PC) showed better pigmenting effect than others in B16 cells. In this study, we examined the mechanism underlying the melanogenic effect of 5D3PC both in vivo and in vitro. To examine the pigmentation effect, the B16 and human melanocyte cell lines, PIG1 and PIG3V melanocytes were incubated with 5D3PC. In animal experiments, C57BL/6 mice received 5% hydroquinone and were administrated with 5D3PC for 30 days. 5D3PC upregulated the melanin synthesis and tyrosinase in B16 cell, PIG1 and PIG3V. The expression level of tyrosinase (TYR), tyrosinase-related protein-1 (TRP-1) and tyrosinase-related protein-2 (TRP-2), microphthalmia-associated transcription factor (MITF), cyclic adenosine monophosphate (cAMP), phosphorylation of cAMP-responsive element binding protein (p-CREB), phosphorylation of p38 mitogen-activated protein kinase (MAPK), c- phosphorylation of Jun N-terminal kinase (p-JNK) was significantly higher in 5D3PC-treated B16 cells. The oral administration of 5D3PC attenuated the depigmentation of the C57BL/6 vitiligo mice model by increasing the numbers of melanin-containing hair follicles, melanogenic protein, and melanogenesis-relative genes expression in skin tissues.

UVB-Induced Secretion of IL-1β Promotes Melanogenesis by Upregulating TYR/TRP-1 Expression In Vitro.

Purpose Ultraviolet radiation (UVR) is one of the exogenous stimuli increasing melanogenesis. UV light, especially UVB, is also a potent inducer of epidermal cytokine release. This study is aimed at determining the underlying mechanisms by which UVB-induced cytokines in keratinocytes regulate melanin production in vitro. Methods Expression levels of mRNA for interleukin- (IL-) 1, IL-1β, IL-6, IL-10, IL-17, and tumor necrosis factor-alpha (TNF-α) were measured using RT-qPCR at various time points after UVB irradiation in C57BL/6 mice and HaCaT cells. NaOH lysis and L-dihydroxyphenylalanine (L-DOPA) oxidation method were used to measure melanin content and tyrosinase (TYR) activity, respectively, in melanoma B16 cells. RT-qPCR and Western blot were used to assess mRNA and protein levels of microphthalmia-associated transcription factor (MITF), TYR, tyrosine-related protein-1 (TRP-1), and tyrosine-related protein-2 (TRP-2) in B16 cells. Finally, expression levels of cyclooxygenase-2 (COX-2) mRNA and stem cell factor (SCF) in HaCaT cells were measured following knockdown of IL-1β using siRNA (siIL-1β). Results UVB irradiation increased IL-1β mRNA expression levels in both C57BL/6 mice and HaCaT cells. The melanin content, TYR activity, and expression levels of TYR and TRP-1 were all raised when B16 cells were treated with 4 pg/l of IL-1. Moreover, IL-1β also upregulated the expression levels of SCF and COX-2 in nonirradiated HaCaT cells. Conversely, knockdown of IL-1β attenuated UVB irradiation-induced upregulation of SCF and COX-2 expression in keratinocytes. Conclusions UVB-induced melanogenesis is mediated in part by IL-1β, leading to upregulation of the TYR/TRP1 expression in melanoma B16 cells. IL-1β can also stimulate the expression of COX-2 and SCF in HaCaT cells, which in turn increase melanin synthesis in melanocytes. These results suggest that anti-inflammatory approaches could possibly mitigate UVB-induced hyperpigmentation.

Melanogenesis Promoting Effect, Antioxidant Activity, and UPLC-ESI-HRMS Characterization of Phenolic Compounds of Argan Leaves Extract.

The use of natural products for the regulation of skin pigmentation is gaining popularity. In the present study, we evaluated the effect of argan leaves extract (ALE) on melanogenesis in B16 melanoma cells, determined its antioxidant activity, then quantified and identified its phenolic components. B16 cells were treated with various concentrations of ALE, then the cell viability and proliferation were assessed using MTT assay while the melanin content was determined using spectrophotometric methods. The expression level of tyrosinase (TYR), tyrosinase related protein-1 (TRP-1) and dopachrome tautomerase (DCT) was evaluated by Western blotting. The antioxidant activity of ALE was investigated using four different assays while UPLC-ESI-HRMS analysis was used to characterize the ALE phenolic profile. Fourteen phenolic compounds were identified, of which six are reported for the first time to be present in ALE. ALE treatment increases the melanin content of B16 cells in a dose-dependent manner without cytotoxicity. This was revealed by the observed ALE-increased expression level of TYR, DCT, and TRP-1. These bioactivities may be mainly attributed to its high flavonoids content. Argan leaves have the potential for use as a treatment for hypopigmentation disorders and as a bioactive component of cosmetic products that aim to increase pigmentation.

Anti-melanogenic property of ginsenoside Rf from Panax ginseng via inhibition of CREB/MITF pathway in melanocytes and ex vivo human skin

BackgroundGinsenosides of Panax ginseng are used to enhance skin health and beauty. The present study aimed to investigate the potential use of ginsenoside Rf (Rf) from Panax ginseng as a new anti-pigmentation agent. MethodsThe anti-melanogenic effects of Rf were explored. The transcriptional activity of the cyclic adenosine monophosphate (cAMP) response element binding protein (CREB) and the expression levels of tyrosinase, microphthalmia-associated transcription factor (MITF), and tyrosinase-related proteins (Tyrps) were evaluated in melanocytes and UV-irradiated ex vivo human skin. ResultsRf significantly inhibited Forskolin (FSK) or UV-stimulated melanogenesis. Consistently, cellular tyrosinase activity and levels of MITF, tyrosinase, and Tyrps were downregulated. Furthermore, Rf suppressed MITF promoter activity, which was stimulated by FSK or CREB-regulated transcription coactivator 3 (CRTC3) overexpression. Increased CREB phosphorylation and protein kinase A (PKA) activity induced by FSK were also mitigated in the presence of Rf. ConclusionRf can be used as a reliable anti-pigmentation agent, which has a scientifically confirmed and reproducible action mechanism, via inhibition of CREB/MITF pathway.

Melanosome-Targeting Near-Infrared Fluorescent Probe with Large Stokes Shift for in Situ Quantification of Tyrosinase Activity and Assessing Drug Effects on Differently Invasive Melanoma Cells.

Tyrosinase (TYR) plays a vital role in melanin biosynthesis and is widely regarded as a relatively specific marker for melanocytic lesions which involve vitiligo, malignant cutaneous melanoma, Parkinson's disease (PD), etc. However, the detection of TYR in living cells with fluorescent probes is usually interfered by diverse endogenous reactive oxygen species (ROS) and reactive nitrogen species (RNS). Herein, we synthesized a melanosome-targeting near-infrared (NIR) fluorescent probe (HB-NP) with a large Stokes shift (195 nm), achieving a highly sensitive and selective in situ detection for intracellular TYR, by incorporating a m-hydroxybenzyl moiety that recognizes TYR specifically and the morpholine unit which facilitates the probe accumulating in the melanosome into a salicyladazine skeleton. When treated with TYR, the probe itself with weak fluorescence is lit up via an inhibited photoinduced electron-transfer (PET) effect and HB-NP shows a strong fluorescence signal (nearly 48-fold enhancement) with a low detection limit of 0.5 U mL-1. HB-NP has been successfully applied in visualizing and in situ quantification of the intracellular TYR activity. Moreover, owing to the different expression levels of TYR, two human uveal melanoma cells with different invasive behaviors are distinguished by means of bioimaging and the effects of the inhibitor, kojic acid, and the up-regulating treatment, psoralen/ultraviolet A, on TYR activity of the two melanoma cells are evaluated. HB-NP is expected to be a useful tool to monitor diseases associated with the abnormal level of melanin and screen medicines for TYR disorder more effectively.

The effects of vitamin B6 compounds on cell proliferation and melanogenesis in B16F10 melanoma cells

B16F10 murine melanoma cells are frequently used for the study of cancer and melanogenesis. The cells are usually cultured in Dulbecco's Modified Eagle Medium, with the addition of 20 µM pyridoxal (PL) or pyridoxine (PN) for vitamin B6. The difference between these vitamin B6 compounds is thought not to affect cell proliferation, whereas their influence on other physiological effects is poorly understood. In the present study, the effects of PL and PN on cell proliferation and melanogenesis in B16F10 cells were compared. At 500 µM PL significantly suppressed cell growth but the growth inhibitory effect of PN was weak. Although neither of the vitamin B6 compounds affected cell growth at 20 µM, melanogenesis was suppressed by 20 µM PL compared with the effect of PN. In addition, the expression levels of tyrosinase, which is the rate-limiting enzyme, correlated with the melanin content. The results of the present study indicate that PL may be more useful for melanoma therapy and suppression of skin pigmentation than PN. The results also signify the importance of medium selection for cell culture.

Coptis chinensis inhibits melanogenesis increasing miR-340-mediated suppression of microphathalmia-associated transcription factor

BackgroundCoptis chinensis (C. chinensis) contains various antioxidants, including berberine, epiberberlin, ferulic acid, magnoflorine, palmatine, and worenine, which have antibacterial, anti-inflammatory, haemostatic, hypotensive, and anticancer effects. In the present study, the melanogenesis-inhibiting effects of C. chinensis were investigated and the molecular mechanisms were elucidated.MethodsThe melanogenesis-inhibiting effect of C. chinensis was verified by measuring melanin contents, melanogenesis-related tyrosinase activities, and mRNA and protein expression levels of tyrosinase and microphthalmia-associated transcription factor (MITF). In addition, changes in miR-340 expression by C. chinensis were verified, and the activity of the miR-340 binding site of the target MITF gene was determined using luciferase reporter assays.ResultsAssays of melanin contents showed that C. chinensis had a skin-whitening effect and controlled mRNA and protein expression levels of tyrosinase. However, C. chinensis controlled protein levels of MITF without affecting mRNA levels. Determinations of miR-340 expression, which directly influences MITF translation, showed increased miR-340 mRNA levels in the presence of C. chinensis. Finally, luciferase reporter assays of the binding site on MITF showed that C. chinensis inhibits melanogenesis by directly controlling the miR-340–MITF axis.ConclusionsThe results of the present study verified the skin-whitening effect of C. chinensis and its molecular mechanisms and indicated that C. chinensis has high potential as an ingredient in skin-whitening cosmetics.

Effects of bavachin and its regulation of melanin synthesis in A375 cells.

The aim of the present study was to investigate the effect of bavachin treatment on A375 cells and the regulation of melanin synthesis. The cultured A375 cells in vitro were treated with bavachin; and the effect of bavachin on cell activity, tyrosinase (TYR) activity and melanin synthesis were respectively tested by the MTT assay, L-dopa oxidation assay and the NaOH lysis assay. The expression levels of TYR and c-Jun N-terminal kinases (JNK) proteins were tested by western blot analysis. The expression levels of TYR, tyrosinase-related protein-1 (TRP-1), TRP-2, extracellular signal-regulated kinase 1 (ERK1), ERK2 and JNK2 mRNA were tested by the reverse transcription-polymerase chain reaction assay. Simultaneously, the effect of estrogen receptor inhibitor (ICI182780) and ERK pathway inhibitor (U0126) was also tested on A375 cells following bavachin. The safe dose of bavachin significantly inhibited melanin synthesis and TYR activity. Bavachin (10 µmol/l) inhibited the expression of TYR and JNK proteins, and the expression of TYR, TRP-1, TRP-2, ERK1, ERK2 and JNK2 mRNA in A375 cells. ICI182780 and U0126 could significantly reverse the bavachin treatment on the protein expression levels and the mRNA expression of TYR, TRP-1, TRP-2, ERK1, ERK2 and JNK2. In conclusion, bavachin inhibited the synthesis of melanin on A375 cells by inhibiting the protein and mRNA expression of TYR, TRP-1, TRP-2, ERK1, ERK2 and JNK2.

Novel cyclic pentapeptide H-15 induces differentiation and inhibits proliferation in murine melanoma B16 cells.

Sansalvamide A is a cyclic depsipeptide that is isolated from a marine fungus of the Fusarium genus. Sansalvamide A exhibits significant antitumor ability. The molecular formula and molecular weight of the novel sansalvamide A derivative H-15 are C29H44BrN5O6 and 637.2475, respectively. In the present study, H-15 was found to inhibit the proliferation and induce the differentiation of murine melanoma B16 cells. A sulforhodamine B colorimetric assay was used to measure the inhibitory effects of 0.1, 1, 10, 50 and 100 µM H-15 on the B16 cells, and the results revealed that the inhibitory effects of H-15 exerted on the B16 cells occurred in a concentration-dependent manner. In addition, the growth curve model of the B16 cells treated with 50 µM H-15 revealed that the effect of H-15 was also time-dependent. The differentiation morphology of the B16 cells was observed subsequent to treating the cells with H-15. An optical microscope was used to observe the differentiation morphology of the cells. In addition, melanin secretion increased in the B16 cells treated with 50 µM H-15. The expression levels of tyrosinase (TYR) were assayed by western blot analysis, and it was found that the cells treated with 50 µM H-15 for 48 h exhibited increased expression of TYR. The results of the present study indicated that H-15 may induce the differentiation of B16 cells.

Withaferin A abolishes the stem cell factor-stimulated pigmentation of human epidermal equivalents by interrupting the auto-phosphorylation of c-KIT in human melanocytes.

We characterized the mechanism(s) underlying the abrogating effect of withaferin A (WFA) on the stem cell factor (SCF)-stimulated pigmentation of human epidermal equivalents (HEEs). Increased gene and protein expression levels of tyrosinase, tyrosinase-related protein1, dopachrome tautomerase, PMEL17, c-KIT and their targeted transcription factor, microphthalmia-associated transcription factor (MITF) were significantly reversed at days 7 and 10, respectively, by treatment with WFA. In WFA-treated normal human melanocytes (NHMs), there was a marked deficiency in the SCF-stimulated series of phosphorylations of c-KIT, Shc, Raf-1, MEK, ERK, MITF and CREB. Treatment with dithiothreitol (DTT) distinctly abolished the suppressive effect of WFA on the SCF-stimulated phosphorylation of c-KIT in NHMs. On the other hand, even after incubation at 4 °C for 2 h with 5 nM SCF, followed by the removal of unbound SCF by washing and then raising the temperature to 37 °C to start the signaling reaction, c-KIT was distinctly phosphorylated to a similar extent by incubation for 15 min with SCF only or with SCF + WFA. These findings indicate that WFA attenuates the SCF-induced activation of c-KIT in NHMs by interrupting the auto-phosphorylation of c-KIT through DTT-suppressible Michael addition thioalkylation reactions without interrupting the binding of SCF to the c-KIT receptor.

Effect of cultured medium of human umbilical cord blood-derived mesenchymal stem cells on melanogenic enzyme activity in mouse B16 melanoma cells

The cultured medium of mesenchymal stem cell is a valuable resource for a variety of stem cell-derived cytokines and growth factors with a potential therapeutic effect on skin diseases. Here, we investigated the effect of the cultured medium of human umbilical cord blood-derived mesenchymal stem cell (CM-hCBSC) on melanogenesis in mouse B16 melanoma cells stimulated by α-melanocyte stimulating hormone (α-MSH). Our results show that CM-hCBSC inhibits melanin synthesis due to the decrease in cellular tyrosinase activity in B16 melanoma cells without cytotoxicity. The activity of melanogenic enzymes such as tyrosinase, tyrosinase-related protein-1 (TRP-1), and TRP-2 were evaluated by western blot and semi-quantitative RT-PCR. The CM-hCBSC down-regulated the protein and mRNA expression levels of tyrosinase and TRP-1 in a dose-dependent manner. In addition, TRP-2 protein and mRNA expression levels were found to be down-regulated to a lesser extent. We also measured the level of cytokines in CM-hCBSC using the Luminex total system. It was found that the top enriched cytokine in the CMhCBSC was interukine-6 (IL-6), known as a potent regulator of melanin synthesis together with IL-1α and tumor necrosis factor α (TNF- α). These results indicate that secretary factors including IL-6 in the CM-hCBSC may inhibit melanin synthesis by down-regulating the expression of tyrosinase and TRP1. This study suggests that CMhCBSC has a therapeutic effect as an anti-melanogenic agent and may be effective against hyperpigmentation disorders.

Anti-melanogenic activity of the novel herbal medicine, MA128, through inhibition of tyrosinase activity mediated by the p38 mitogen-activated protein kinases and protein kinase signaling pathway in B16F10 cells.

Background:Recently, our research group developed MA128, a novel herbal medicine, and demonstrated that MA128 is effective for the treatment of asthma and atopic dermatitis (AD). In particular, postinflammatory hyper-pigmentation in AD mice was improved with MA128 treatment. Thus, in this study, we determined the effect of MA128 on melanogenesis and its underlying mechanism in murine B16F10 melanoma cells.Materials and Methods:After treatment with MA128 at 100 and 250 μg/mL and/or alpha-melanocyte stimulating hormone (α-MSH) (1 μM), cellular melanin content and tyrosinase activity in B16F10 cells were measured. Using western blotting, expression levels of tyrosinase, tyrosinase-related protein-1 (TRP-1), TRP-2, microphthalmia-associated transcription factor (MITF), and activation of c-AMP-dependent protein kinase (PKA), c-AMP-related element binding protein (CREB) and mitogen-activated protein kinases (MAPKs) were examined.Results:MA128 significantly inhibited melanin synthesis and tyrosinase activity in a resting state as well as α-MSH-stimulating condition, and significantly decreased the expression of tyrosinase, TRP-1, TRP-2 and MITF. In addition, phosphorylation of PKA and CREB by α-MSH stimulation was efficiently blocked by MA128 pretreatment. Moreover, MA128 as an herbal mixture showed synergistic anti-melanogenic effects compared with each single constituent herb.Conclusion:MA128 showed anti-melanogenic activity through inhibition of tyrosinase activity mediated by p38 MAPK and PKA signaling pathways in B16F10 cells. These results suggest that MA128 may be useful as an herbal medicine for controlling hyper-pigmentation and as a skin-whitening agent.

Ssanghwa-tang, an oriental herbal cocktail, exerts anti-melanogenic activity by suppression of the p38 MAPK and PKA signaling pathways in B16F10 cells

BackgroundSsanghwa-tang (SHT) is a widely used medication for the treatment of fatigue, pain, inflammation, hypothermia, erectile dysfunction, cancer, and osteoporosis in Asia, however, role of SHT on the melanin synthesis has not been checked previously. Thus, the present study was designed to determine the effect of SHT on α-melanocyte stimulating hormone (α-MSH)-induced melanogensis and its mechanisms of action in murine B16F10 melanoma cells.MethodCellular melanin content and tyrosinase activity in murine B16F10 melanoma cells were determined after α-MSH stimulation with or without pre-treatment of SHT at the concentration of 250 and 500 μg/ml. Expression level of tyrosinase, tyrosinase-related protein 1 (TRP-1), TRP-2, microphthalmia-associated transcription factor (MITF), and activation of c-AMP-dependent protein kinase (PKA), c-AMP-related element binding protein (CREB), and mitogen-activated protein kinases (MAPKs) were examined by Western blot analysis.ResultsSHT significantly inhibited α-MSH-induced melanin synthesis and tyrosinase activity, and also decreased α-MSH-induced expression of MITF, tyrosinase, and TRP-1. In addition, SHT remarkably suppressed tyrosinase, CRE, and MITF luciferase reporter activity in a resting state as well as in α-MSH-stimulating condition. Phosphorylation of p38 MAPK by α-MSH stimulation was efficiently blocked by SHT pre-treatment. Moreover, SHT as an herbal cocktail showed synergistic anti-melanogenic effect compared with that of each single constituent herb.ConclusionSHT efficiently inhibited c-AMP-induced melanin synthesis in B16F10 cells via suppression of PKA and p38 MAPK signaling pathways and subsequently decreased the level of CREB phosphorylation, MITF, and melanogenic enzymes. These results indicate that SHT may be useful as herbal medicine for treating hyperpigmentation and cosmetics as a skin-whitening agent.

Abstract 5242: Effect of total saponins of Gynostemma pentaphyllum on melanogenesis and anti-melanoma effect in B16 cells.

Abstract Melanogenesis is a physiological process of melanin production in response to UV exposure, which is modulated through multi-signaling pathways including cAMP/PKA, Wnt/β-catenin and MAPK signaling cascades. In this study, we investigated both the melanogenesis and anti-melanoma effects of total saponins of Gynostemma pentaphyllum (GpS). Our results showed that non-toxic dosages of GpS stimulated tyrosinase activity and increased melanin content in a dose-dependent manner. Western blot analysis showed that GpS treatment significantly up-regulated the expression levels of the melanogenic proteins, tyrosinase (TYR) and microphthalmia-associated transcription factor (MITF) in a dose-dependent manner. The p-CREB, which is the down-stream target of PKA is also elevated upon GpS treatment. We further observed that H89, a PKA inhibitor, attenuated the GpS induced tyrosinase activity, melanin content, and the protein expression of p-CREB and the nuclear β-catenin. To identify the active saponins, GpS was fractionated in the MCI-CHP 20P column and eluted with methanol in a gradient of 50 to 100% . The resulting ten fractions were tested for their melanogensis activities. We found that Fractions 5 to 9 showed the strongest effect in melanin synthesis in B16 cultures, while up-regulated the expression levels of TYR and MITF, while Fractions 7 to 9 increased nucleus β-catenin protein expression. Further purification of GpS is under way. Our early works showed that GpS exhibits strong anti-cancer effects in both in cellular and animal model. We were wonder whether GpS would exert anti-cancer effect against melanoma. To address this question, we tested and showed that GpS inhibited B16 cells migration in a dose-dependent manner. Meanwhile, GpS also increased G1/S ratio of the GpS-treated B16 cells, suggesting that GpS may act as G1 inhibitor. Our study seems to be in line with the recent reports that stimulation of melanogenesis might be associated with the anti-melanoma effect by decreasing proliferation and invasiveness of melanoma (Chien, et al.,2009). Based on the above results, we proposed that GpS might exert the anti-melanoma effect by stimulating the melanogenesis through the activation of cAMP/PKA and Wnt/β-catenin signaling pathways. Citation Format: Ting Fung Tsang, William Chi Shing Tai, Wendy Wen Luan Hsiao. Effect of total saponins of Gynostemma pentaphyllum on melanogenesis and anti-melanoma effect in B16 cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5242. doi:10.1158/1538-7445.AM2013-5242

Activation of MITF by Argan Oil Leads to the Inhibition of the Tyrosinase and Dopachrome Tautomerase Expressions in B16 Murine Melanoma Cells

Argan (Argania spinosa L.) oil has been used for centuries in Morocco as cosmetic oil to maintain a fair complexion and to cure skin pimples and chicken pox pustules scars. Although it is popular, the scientific basis for its effect on the skin has not yet been established. Here, the melanogenesis regulatory effect of argan oil was evaluated using B16 murine melanoma cells. Results of melanin assay using B16 cells treated with different concentrations of argan oil showed a dose-dependent decrease in melanin content. Western blot results showed that the expression levels of tyrosinase (TYR), tyrosinase-related protein 1 (TRP1), and dopachrome tautomerase (DCT) proteins were decreased. In addition, there was an increase in the activation of MITF and ERK1/2. Real-time PCR results revealed a downregulation of Tyr, Trp1, Dct, and Mitf mRNA expressions. Argan oil treatment causes MITF phosphorylation which subsequently inhibited the transcription of melanogenic enzymes, TYR and DCT. The inhibitory effect of argan oil on melanin biosynthesis may be attributed to tocopherols as well as the synergistic effect of its components. The results of this study provide the scientific basis for the traditionally established benefits of argan oil and present its therapeutic potential against hyperpigmentation disorders.

Silencing of GPNMB by siRNA Inhibits the Formation of Melanosomes in Melanocytes in a MITF-Independent Fashion

BackgroundMelanosomes are specialized membrane-surrounded organelles, which are involved in the synthesis, storage and transport of melanin. Glycoprotein (transmembrane) non-metastatic melanoma protein b (GPNMB), a melanosome-specific structural protein, shares significant amino acid sequence homology with Pmel-17. Proteomic analysis demonstrated that GPNMB is present in all stages (I-IV) of melanosomes. However, little is known about the role of GPNMB in melanosomes.Methodology/Principal FindingsUsing real-time quantitative PCR, Western blotting and immunofluorescence analysis, we demonstrated that the expression of GPNMB in PIG1 melanocytes was up-regulated by ultraviolet B (UVB) radiation. Transmission electron microscopy analysis showed that the total number of melanosomes in PIG1 melanocytes was sharply reduced by GPNMB-siRNA transfection. Simultaneously, the expression levels of tyrosinase (Tyr), tyrosinase related protein 1 (Trp1), Pmel17/gp100 and ocular albinism type 1 protein (OA1) were all significantly attenuated. But the expression of microphthalmia-associated transcription factor (MITF) was up-regulated. Intriguingly, in GPNMB silenced PIG1 melanocytes, UVB radiation sharply reduced MITF expression.ConclusionOur present work revealed that the GPNMB was critical for the formation of melanosomes. And GPNMB expression down-regulation attenuated melanosome formation in a MITF-independent fashion.

Molecular cloning and expression analysis of tyrosinase gene in the skin of Jining gray goat (Capra hircus)

Tyrosinase is the key regulatory enzyme of melanogenesis and plays a major role in mammal coat color. For the first time, we have sequenced and characterized the tyrosinase (TYR) of Jining Gray Goat (Capra hircus), which is the world-famous fur-bearing animal with its special color and pattern. The full-length cDNA was cloned by a reverse-transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA end (RACE) method. As a result, one 2131-bp nucleotide sequence representing the full-length cDNA of TYR was obtained. The entire open reading frame (ORF) of the TYR is 1593 bp and encodes for 530 amino acids, which is well conserved compared with TYR of various species with higher degree of sequence similarity with other mammalian (74-99 %) than amphibian, aves, and fishes (56-73 %). The deduced amino acids contained one signal peptide, one transmembrane domain, five N-linked glycosylation sites, and two copper binding sites. The result of real-time quantitative PCR showed that the expression level of TYR was the highest in the dark-gray goats and the lowest in the light-gray ones, while the goats of dark-gray individuals have more than 50 % black fiber and light-gray ones less than 30 %. During the whole life of Jining gray goat, TYR expression level changes with certain regularity and their coat color will change correspondingly by investigating the expression level in ten development stages. After comparing the result and the coat phenotype, we presume that it seems to have a positive relationship between the color depth of coat and the expression level of TYR.