Microphthalmia-associated Transcription Factor Expression Research Articles

YTHDF2 Regulates Advanced Glycation End Products-Induced Melanogenesis through Inhibiting A20 Expression in Human Dermal Fibroblasts.

Fibroblast A20 suppresses advanced glycation end products (AGEs)-induced melanogenesis by inhibiting NLRP3 inflammasome activation. AGEs repress A20 expression and significantly m6A-methylate A20 mRNA in fibroblasts. YTHDF2 is the most studied m6A reader protein and can accelerate degradation of m6A-modified mRNA. Whether YTHDF2 regulates AGEs-induced A20 expression and pigmentation is unknown. In this study, we confirmed that YTHDF2 inversely regulated AGEs-BSA-inhibited A20 expression but facilitated AGEs-BSA-activated NF-κB signaling and NLRP3 inflammasome in fibroblasts via YTHDF2 knockdown and overexpression experiments. Mechanistically, YTHDF2 bound to m6A-modified A20 mRNA induced by AGEs-BSA and increased its degradation. Moreover, fibroblast YTHDF2 robustly promoted AGEs-BSA-induced IL-18 level in coculture supernatants and melanin content, tyrosinase activity, and expression of microphthalmia-associated transcription factor and tyrosinase in melanocytes, which were significantly blocked by IL-18 binding protein. Further, fibroblast YTHDF2 markedly increased AGEs-BSA-induced epidermal melanin level in cocultured ex vivo skin and MAPKs activation in melanocytes. Importantly, upregulated dermal YTHDF2 expression was negatively correlated with dermal A20 level and positively associated with both epidermal melanin and dermal AGEs content in sun-exposed skin and lesions of melasma and solar lentigo. These findings suggest that fibroblast YTHDF2 positively regulates AGEs-induced melanogenesis mainly via A20/ NF-κB /NLRP3 inflammasome/ IL-18 /MAPKs axis in an m6A-dependent manner and functions in photoaging-induced hyperpigmentation skin disorders.

Kunzea Ericoides (Kanuka) Leaf Extracts Show Moisturisation, Antioxidant, and UV Protection Effects in HaCaT Cells and Anti-melanogenesis Effects in B16F10 Cells.

Kunzea ericoides (kanuka) products are well-known for their potent medicinal values in antioxidant and anti-inflammatory applications. The present study identified various compounds, such as chlorogenic acid, gallic acid, quercetin, and (E)-ferulic acid in the kanuka leaf extract, showing its potential use in maintaining skin health. The influence of kanuka leaf extract upon epidermal cells concerning cytotoxicity and in vitro activities of moisturisation, antioxidation, UV protection, and anti-melanogenesis effects were explored in the study. Kanuka leaf extract demonstrated significant promotion in the proliferation of HaCaT and B16F10 cells. After incubation with kanuka leaf extract, the content of ROS and DPPH in HaCaT was significantly decreased; at the same time, more SOD was produced. Furthermore, hyaluronidase-1 (HYAL-1) and HYAL-4 expressions were inhibited, while the aquaporin 3 (AQP-3) content was significantly increased in HaCaT. Kanuka leaf extract also inhibited the expressions of matrix metalloproteinases-1 (MMP-1) and MMP-14 in UV-induced HaCaT cells. In the B16F10 cell line, melanin and tyrosinase production were decreased under the presence of kanuka leaf extract, and the expressions of microphthalmia-associated transcription factor (MITF), tyrosinase-related protein-1 (TYRP-1), and TYRP-2 were also inhibited. The study validated kanuka leaf extract as an effective natural product against photoaging and melanogenesis.

Cytocompatibility of electrospun poly-L-lactic acid membranes for Bruch's membrane regeneration using human embryonic stem cell-derived retinal pigment epithelial cells.

Cell replacement therapy is under development for dry age-related macular degeneration (AMD). A thin membrane resembling the Bruch's membrane is required to form a cell-on-membrane construct with retinal pigment epithelial (RPE) cells. These cells have been differentiated from human embryonic stem cells (hESCs) in vitro. A carrier membrane is required for cell implantation, which is biocompatible for cell growth and has dimensions and physical properties resembling the Bruch's membrane. Here a nanofiber electrospun poly-L-lactic acid (PLLA) membrane is tested for capacity to support cell growth and maturation. The requirements for laminin coating of the membrane are identified here. A porous electrospun nanofibrous PLLA membrane of ∼50 nm fiber diameter was developed as a prototype support for functional RPE cells grown as a monolayer. The need for laminin coating applied to the membrane following treatment with poly-L-ornithine (PLO), was identified in terms of cell growth and survival. Test membranes were compared in terms of hydrophilicity after laminin coating, mechanical properties of surface roughness and Young's modulus, porosity and ability to promote the attachment and proliferation of hESC-RPE cells in culture for up to 8 weeks. Over this time, RPE cell proliferation, morphology, and marker and gene expression, were monitored. The functional capacity of cell monolayers was identified in terms of transepithelial electrical resistance (TEER), phagocytosis of cells, as well as expression of the cytokines, vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF). PLLA polymer fibers are naturally hydrophobic, so their hydrophilicity was improved by pretreatment with PLO for subsequent coating with the bioactive protein laminin. They were then assessed for amount of laminin adsorbed, contact angle and uniformity of coating using scanning electron microscopy (SEM). Pretreatment with 100% PLO gave the best result over 10% PLO treatment or no treatment prior to laminin adsorption with significantly greater surface stiffness and modulus. By 6 weeks after cell plating, the coated membranes could support a mature RPE monolayer showing a dense apical microvillus structure and pigmented 3D polygonal cell morphology. After 8 weeks, PLO (100%)-Lam coated membranes exhibited the highest cell number, cell proliferation, and RPE barrier function measured as TEER. RPE cells showed the higher levels of specific surface marker and gene expression. Microphthalmia-associated transcription factor expression was highly upregulated indicating maturation of cells. Functionality of cells was indicated by expression of VEGF and PEDF genes as well as phagocytic capacity. In conclusion, electrospun PLLA membranes coated with PLO-Lam have the physical and biological properties to support the distribution and migration of hESC-RPE cells throughout the whole structure. They represent a good membrane candidate for preparation of hESC-RPE cells as a monolayer for implantation into the subretinal space of AMD patients.

The Antioxidant and Whitening Effect of Miracle Fruit (Synsepalum dulcificum) Seed and Leaf Methanol Extracts

The seed and leaf 70% methanol extracts of miracle fruit (Synsepalum dulcificum) were investigated for its whitening activity for application as a functional ingredient in cosmetic products. At the leaf extract concentration of 100 mg/ml, the DPPH radical scavenging activity was found to be 94.58%, the ABTS+ radical scavenging activity was 36.62%. The total polyphenolic content of seed and leaf extract was 18.76 mgGAE/g, 71.42 mgGAE/g, respectively. The seed and leaf extracts reduced both tyrosinase activity and L-DOPA oxidation in a concentration-dependent manner. In B16F10 mouse melanoma cells, leaf extract inhibited 30% of melanin synthesis at 100 mg/ml. Miracle fruit seed and leaf extracts also inhibited the expression of melanogenesis genes such as microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein (TRP)-1. Moreover, reverse transcription-polymerase chain reaction of the extract showed that the mRNA expression of MITF, tyrosinase, and TRP-1 was decreased. The data suggested a protective role for the Synsepalum dulcificum seed and leaf extracts against melanogenesis.

Inhibitory Effects of Fermented Sprouted Oat Extracts on Oxidative Stress and Melanin Overproduction.

Hyperpigmentation occurs due to irregular secretion of melanin pigment in the skin. This can affect quality of life depending on its severity, so prevention and management are essential. Oats (Avena sativa L.), a grain consumed worldwide, are known to offer improved health benefits upon germination and fermentation. This study is aimed to investigate the protective effects of lactobacilli-fermented sprouted oat extracts on oxidative stress and melanin overproduction in vitro. The anti-melanogenic effect was investigated using melanin content and tyrosinase activity assays in B16F10 cells, as well as a mushroom tyrosinase-based enzyme inhibition assay. The results showed that L. casei-fermented oat extracts were the most effective for reducing melanin formation by reducing the mRNA expression of microphthalmia-associated transcription factor, tyrosinase, and tyrosinase-related protein 2. Furthermore, L. casei fermentation was effective in improving the total phenolic, flavonoid, and avenanthramide A contents of sprouted oat extracts. The results also demonstrated the antioxidant effects of L. casei-fermented sprouted oat extracts in promoting DPPH radical-scavenging activity, superoxide dismutase-like activity, and reduction in reactive oxygen species levels. Overall, the findings indicate that fermented sprouted oat extracts are promising candidates for antioxidant and anti-hyperpigmentation treatments.

Abstract 5425: MITF/TFE regulatory programs in neural crest migration are co-opted in melanoma metastasis

Abstract Introduction: Microphthalmia-associated transcription factor (MITF) is a critical regulator of melanocyte differentiation and melanoma oncogenesis. Melanoma expression profiling has revealed a strong trend between low MITF expression levels and invasive behavior. However, it is unclear how low levels of MITF are connected to invasive behavior. Preliminary data from our lab has identified transcription factor E3 (TFE3), a MITF paralog, as a transcriptional regulator in MITF-low melanoma states. We hypothesize that in melanoma cells with low MITF levels, TFE3 promotes invasion. To assess the possibility that the antagonistic regulatory interaction between MITF and a paralog was coopted from the embryo, we examine migratory behavior of neural crest cells in zebrafish embryos that are wild-type, mitfa loss-of-function (LOF) mutants, tfec (TF3 ortholog) LOF mutants, or mitfa/tfec double LOF embryos. Methods: We evaluated TFE3 levels by Western blot in a panel of melanoma cell lines known to express a range of MITF expression levels. We mutated TFE3 exon 4, which encodes the DNA binding domain, using a single guide RNA, and assessed cellular invasive potential using an in vitro transwell invasion assay. CUT&RUN sequencing was used to profile TFE3 genomic binding. Zebrafish embryos were generated in which the mitfa promoter drove expression of RNA encoding green fluorescent protein (GFP), and of the genotypes mentioned above. From transgenic wild-type and mitfa LOF mutant embryos we isolated GFP-expressing cells and conducted single cell-RNA sequencing. We assessed migration of GFP-labeled cells by fluorescent microscopy in 20-48 hour post fertilization zebrafish embryos of all genotypes mentioned above. Results: We found that melanoma cell lines with high levels of MITF (SKMEL3 and SKMEL28) had low levels of TFE3 protein, and those with low levels of MITF (A375 and RPMI 7952) had high levels of TFE3 protein. The TFE3-high cell lines were more invasive in vitro than the TFE3-low cell lines. TFE3-high cell lines depleted of TFE3 were less in invasive in vitro than parental cells. CUT&RUN profiling of TFE3 demonstrates that TFE3 binds mesenchymal-like enhancers in MITF-low cell lines. Single cell RNA sequencing revealed that in a melanocyte precursor cluster present in both wild types and in mitfa mutants, expression of tfec was higher in the latter. Finally, migration of GFP-expressing cells was higher in mitfa LOF mutant embryos than in mitfa/tfec double LOF mutant embryos. Conclusion: These data indicate that reduction of MITF expression up-regulates TFE3 expression in melanoma and tfec in zebrafish melanocytes, although the mechanism of this regulation is unclear. They also show that TFE3 and Tfec promote migration of metastatic melanoma and melanocyte precursors, respectively. Because regulatory mechanisms in cancer are often coopted from embryonic cells, studying the embryo may illuminate cancer pathogenesis. Citation Format: Jeremy Chang, Katelyn Campbell, Rachel Moore, Robert Cornell, Colin Kenny. MITF/TFE regulatory programs in neural crest migration are co-opted in melanoma metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5425.

MITF regulates the subcellular location of HIF1α through SUMOylation to promote the invasion and metastasis of daughter cells derived from polyploid giant cancer cells.

High concentrations of cobalt chloride (CoCl2) can induce the formation of polyploid giant cancer cells (PGCCs) in various tumors, which can produce daughter cells with strong proliferative, migratory and invasive abilities via asymmetric division. To study the role of hypoxia‑inducible factor (HIF) 1α in the formation of PGCCs, colon cancer cell lines Hct116 and LoVo were used as experimental subjects. Western blotting, nuclear and cytoplasmic protein extraction and immunocytochemical experiments were used to compare the changes in the expression and subcellular localization of HIF1α, microphthalmia‑associated transcription factor (MITF), protein inhibitor of activated STAT protein4 (PIAS4) and von Hippel‑Lindau disease tumor suppressor (VHL) after treatment with CoCl2. The SUMOylation of HIFα was verified by co‑immunoprecipitation assay. After inhibiting HIF1α SUMOylation, the changes in proliferation, migration and invasion abilities of Hct116 and LoVo were compared by plate colony formation, wound healing and Transwell migration and invasion. In addition, lysine sites that led to SUMOylation of HIF1α were identified through site mutation experiments. The results showed that CoCl2 can induce the formation of PGCCs with the expression level of HIF1α higher in treated cells than in control cells. HIF1α was primarily located in the cytoplasm of control cell. Following CoCl2 treatment, the subcellular localization of HIF1α was primarily in the nuclei of PGCCs with daughter cells (PDCs). After treatment with SUMOylation inhibitors, the nuclear HIF1α expression in PDCs decreased. Furthermore, their proliferation, migration and invasion abilities also decreased. After inhibiting the expression of MITF, the expression of HIF1α decreased. MITF can regulate HIF1α SUMOylation. Expression and subcellular localization of VHL and HIF1α did not change following PIAS4 knockdown. SUMOylation of HIF1α occurs at the amino acid sites K391 and K477 in PDCs. After mutation of the two sites, nuclear expression of HIF1α in PDCs was reduced, along with a significant reduction in the proliferation, migration and invasion abilities. In conclusion, the post‑translation modification regulated the subcellular location of HIF1α and the nuclear expression of HIF1α promoted the proliferation, migration and invasion abilities of PDCs. MITF could regulate the transcription and protein levels of HIF1α and participate in the regulation of HIF1α SUMOylation.

Ginsenoside Rf in wild ginseng adventitious roots extract inhibits melanogenesis via cAMP/PKA and NO/cGMP signalling pathways in α-melanocyte-stimulating hormone-stimulated B16F10 mouse melanoma cells and zebrafish

The scarcity of more effective wild ginseng has severely limited its use, culturing of adventitious roots from wild ginseng were its good substitute. In this study, we found ginsenoside Rf as the special component in adventitious roots extract significantly decreased melanin levels and tyrosinase activity in B16F10 cells and zebrafish, and suppressed the expression of microphthalmia-associated transcription factor and melanogenic enzymes in B16F10 cells. Notably, Rf treatment of B16F10 cells led to reduced cell levels of adenosine cyclic 3′, 5′-monophosphate (cAMP), nitric oxide (NO), and guanoside cyclic 3′, 5′-monophosphate (cGMP), and reduced activities of adenylate cyclase (AC), protein kinase A (PKA), guanylate cyclase (GC), and protein kinase G (PKG), which suggest Rf anti-melanogenic activity potentially involved inhibition of AC/cAMP/PKA and NO/GC/cGMP/PKG signalling pathway. This work provides experimental basis for skin-lightening effect of wild ginseng adventitious roots and their functional part.

Chemical Composition and Skin-Whitening Activities of Siegesbeckia glabrescens Makino Flower Absolute in Melanocytes

Siegesbeckia glabrescens Makino (SGM) has been traditionally used to treat many disorders, including rheumatoid arthritis, hypertension, and acute hepatitis. However, the biological activities of SGM in skin remain unclear. The present study explored the effects of SGM flower absolute (SGMFAb) on skin-whitening-linked biological activities in B16BL6 cells. SGMFAb was extracted using hexane, and its composition was analyzed through gas chromatography/mass spectrometry analysis. The biological effects of SGMFAb on B16BL6 melanoma cells were detected via WST and BrdU incorporation assays, ELISA, and immunoblotting. SGMFAb contained 14 compounds. In addition, SGMFAb was noncytotoxic, attenuated the serum-induced proliferation of, and inhibited melanin synthesis and tyrosinase activity in α-MSH-exposed B16BL6 cells. SGMFAb also reduced the expressions of MITF (microphthalmia-associated transcription factor), tyrosinase, tyrosinase-related protein (TRP)-1, and TRP-2 in α-MSH-exposed B16BL6 cells. Moreover, SGMFAb downregulated the activation of p38 MAPK, ERK1/2, and JNK in α-MSH-stimulated B16BL6 cells. In addition, SGMFAb reduced the expressions of three melanosome-transport-participating proteins (myosin Va, melanophilin, and Rab27a) in α-MSH-stimulated B16BL6 cells. These results indicate that SGMFAb positively influences skin whitening activities by inhibiting melanogenesis and melanosome-transport-related events in B16BL6 cells, and suggest that SGMFAb is a promising material for developing functional skin whitening agents.

Prognostic significance of melanogenesis pathway and its association with the ultrastructural characterisation of melanosomes in uveal melanoma

BackgroundPigmentation could be a relevant prognostic factor in uveal melanoma (UM) development. Microphthalmia-associated transcription factor (MITF) regulates melanin synthesis by activating tyrosinase-related protein 2 (TYRP2) and silver protein (SILV) that...

Potential role of the cell-penetrating peptide-conjugated soluble N-ethylmaleimide-sensitive factor attachment protein receptor motif of vesicle-associated membrane protein 2-patterned peptide in novel cosmeceutical skin product development.

This study aimed to investigate and verify the effect of cell-penetrating peptide (CPP)-conjugated soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) motif of vesicle-associated membrane protein 2 (VAMP2)-patterned peptide (INCI name: Acetyl sh-Oligopeptide-26 sh-Oligopeptide-27 SP, trade name: M.Biome-BT) on improving skin function in vitro. The cytotoxicity of CPP-conjugated SNARE motif of VAMP2-patterned peptide (CVP) was investigated using the 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyl tetrazolium bromide (MTT) assay against B16-F10 cells and human dermal fibroblasts (HDFs) and a reconstructed skin irritation test. The anti-wrinkle activity of M.Biome-BT was determined by assessing the release of norepinephrine and dopamine in PC-12 cells via ELISA. The skin-whitening effects of CVP were assessed in B16-F10 cells by measuring the intra- and extracellular melanin contents and expression levels of melanin production-related genes, such as microphthalmia-associated transcription factor (MITF), tyrosinase (TYR), tyrosinase-related protein-1 (TRP-1), and TRP-2. CVP is not cytotoxic to B16-F10 cells and HDFs, and no skin irritation was observed. CVP treatment considerably diminished K+ -induced norepinephrine and dopamine secretion compared with the non-treated control group (62% and 40%, respectively). Additionally, the inhibition ability of CVP on norepinephrine and dopamine release was comparable to that of botulinum neurotoxin type A (BoNT/A). CVP also increased intracellular melanin content in a dose-dependent manner, whereas extracellular melanin content decreased (76%-85%). However, CVP treatment did not affect the mRNA expression of MITF, TYR, TRP-1, and TRP-2. These results suggest that CVP does not inhibit melanin production; however, it may induce a whitening effect by inhibiting melanin transport. Taken together, our findings indicate that CVP could be used as an active and safe cosmeceutical ingredient for antiaging applications.

A20 ameliorates advanced glycation end products-induced melanogenesis by inhibiting NLRP3 inflammasome activation in human dermal fibroblasts

BackgroundAdvanced glycation end products (AGEs) promote melanogenesis through activating NLRP3 inflammasome in fibroblasts. Although A20 has been highlighted to inhibit NLRP3 inflammasome activation, its roles and mechanisms remain elusive in photoaging-associated pigmentation. ObjectivesTo determine the significance of fibroblast A20 in AGEs-induced NLRP3 inflammasome activation and pigmentation. MethodsThe correlation between A20 and AGEs or melanin was studied in sun-exposed skin and lesions of melasma and solar lentigo. We then investigated A20 level in AGEs-treated fibroblast and the effect of fibroblast A20 overexpression or knockdown on AGEs-BSA-induced NLRP3 inflammasome activation and pigmentation, respectively. Finally, the severity of NLRP3 inflammasome activation and pigmentation was evaluated after mice were injected intradermally with A20-overexpression adeno-associated virus and AGEs-BSA. ResultsDermal A20 expression was decreased and exhibited negative correlation with either dermal AGEs deposition or epidermal melanin level in sun-exposed skin and pigmentary lesions. Moreover, both AGEs-BSA and AGEs-collagen robustly decreased A20 expression via binding to RAGE in fibroblasts. Further, A20 overexpression or depletion significantly decreased or augmented AGEs-BSA-induced activation of NF-κB pathway and NLRP3 inflammasome and IL-18 production and secretion in fibroblasts, respectively. Importantly, fibroblast A20 potently repressed AGEs-BSA-stimulated melanin content，tyrosinase activity，and expression of microphthalmia-associated transcription factor and tyrosinase in melanocytes. Particularly, fibroblast A20 significantly abrogated AGEs-BSA-promoted melanogenesis in ex vivo skin and mouse models. Additionally, fibroblast A20 inhibited AGEs-BSA-activated MAPKs in melanocytes and the epidermis of ex vivo skin. ConclusionsFibroblast A20 suppresses AGEs-stimulate melanogenesis in photoaging-associated hyperpigmentation disorders by inhibiting NLRP3 inflammasome activation.

Atractylodes lancea rhizome derived exosome-like nanoparticles prevent alpha-melanocyte stimulating hormone-induced melanogenesis in B16-F10 melanoma cells

Aberrant melanin overproduction can significantly impact an individual's appearance and cause mental and psychological distress. Current inhibitors of melanin production exert harmful side effects due to inadequate selectivity; thus a need to develop more selective melanin synthesis inhibitors is necessary. Extracellular vesicles are important agents of intercellular signalling in prokaryotes and eukaryotes. Recently, plant-derived nanoparticles, similar to mammalian exosomes, have attracted attention for their use in health research. In this study, to investigate the potential of plant-derived exosome-like nanoparticles (ELNs) as inhibitors of melanin production, we used hot water to extract ELNs from the rhizome of Atractylodes lancea (A-ELNs). The size of A-ENLs ranged from 34 to 401 nm and carried three microRNA: ath-miR166f, ath-miR162a-5p, and ath-miR162b-5p. These A-ENLs were applied to B16-F10 melanoma cells treated with α-melanocyte-stimulating hormone (α-MSH). After A-ELNs were taken up by B16-F10 cells, their melanin levels were significantly reduced. Furthermore, A-ELNs significantly reduced tyrosinase activity in B16-F10 cells and mRNA expression of microphthalmia-associated transcription factor (Mitf), tyrosinase, tyrosinase-related protein 1, and DOPA chrome tautomerase. These results suggest that A-ELN suppresses melanogenic enzymes expression by downregulating Mitf, thereby inhibiting melanin synthesis. Hence, A-ELN can be developed into a novel topical drug after additional studies and optimization.

Histone acetylation regulates BMMCs recognition of foot-and-mouth disease virus-like particles.

Foot-and-mouth disease (FMD) is one of the most economically and socially devastating diseases affecting animal agriculture worldwide. Foot-and-mouth disease virus (FMDV) virus-like particles (VLPs) have been widely studied as a candidate vaccine. Mast cells (MCs) are highly versatile innate immunity cells that perform various functions in regulating innate and adaptive immune responses. Recently, we found that MCs can recognize recombinant FMDV VP1-VP4 protein to produce various cytokines with differential expression, suggesting that this may be epigenetically regulated. In this study, we evaluated the effect of trichostatin A (TSA), a histone deacetylase inhibitor, on bone marrow-derived mast cells (BMMCs) recognition of FMDV-VLPs in vitro. BMMCs can recognize FMDV-VLPs via mannose receptors (MRs) and resulted in enhanced expression and secretion of tumour necrosis factor α (TNF-α) and interleukin (IL)-13. Nevertheless, BMMCs recognition of FMDV-VLPs to secrete IL-6 was irrelevant to MRs, and MRs may play a negative regulation for IL-10 secretion. Pre-treatment with TSA caused decreased expression of IL-6, TNF-α and IL-13, and increased expression of IL-10. Furthermore, the expression of nuclear factor-kappa B (NF-κB) was supressed in TSA treated BMMCs, suggesting histone acetylation may alter NF-κB expression to influence the TNF-α and IL-13 secretion. Pre-treatment with TSA had no influence on the expression of microphthalmia-associated transcription factor (MITF) and GATA-2. These data therefore suggest that altered histone acetylation regulates the immune responses induced by BMMCs recognition of FMDV-VLPs, providing an understanding and theory basis for the prevention and control of FMD based MCs.

Role of microphthalmia-associated transcription factor in uveal melanoma and its association with clinicopathological parameters.

153 Background: High melanin content could lead to high metastatic potential in Uveal Melanoma (UM). In the Asian population, Microphthalmia-Associated Transcription Factor (MITF) regulates the melanogenesis pathway and activates Silver Protein (SILV) for eumelanin synthesis. MITF also stimulates the hypoxia–inducible factor 1-alpha (HIF-1α) gene that regulates hypoxia around the tumor microenvironment. Although their oncogenic potential has been observed in a variety of malignancies, MITF and SILV have not been investigated in UM in the Asian population. Therefore, our study aimed to detect the prognostic significance of MITF, SILV, and HIF1-α gene/protein expression levels in UM patients. Methods: Immunohistochemistry of MITF, SILV & HIF-1 α was performed on 82 UM tissue samples. Western blot of all three markers was carried out on representative cases. The mRNA expression level was done by qRT-PCR in 70 fresh UM cases. Cox proportional hazard model and log-rank test were used to determine the prognostic outcome of these markers. Results: MITF and SILV proteins were expressed in 56% and 70% of cases, respectively. High pigmentation, BAP1 loss, and HIF-1α expression were statistically correlated with MITF and SILV protein expression. Upregulation of both genes was found in more than 50% of cases at the mRNA level. This was also statistically significant with high pigmentation and HIF-1α mRNA expression. High expression of MITF protein showed reduced disease-free survival. Conclusions: Our study highlighted the fact that MITF and SILV could be potential biomarkers in UM development. Hence, it might play a key role in future therapeutic target.

EGCG, GCG, TFDG, or TSA Inhibiting Melanin Synthesis by Downregulating MC1R Expression

Without affecting cell viability, epigallocatechin gallate (EGCG), gallocatechin gallate (GCG), theaflavine-3,3′-digallate (TFDG), or theasinensin A (TSA) have been found to effectively reduce intracellular melanin content and tyrosinase (TYR) activity. However, studies on the anti-melanogenic mechanism of the above samples remain weak, and the activities of these samples in regulating melanogenesis at the molecular level lack comparison. Using B16F10 cells with the α-melanocyte-stimulating hormone (α-MSH) stimulation and without the α-MSH stimulation as models, the effects of EGCG, GCG, TFDG, or TSA on cell phenotypes and expression of key targets related to melanogenesis were studied. The results showed that α-MSH always promoted melanogenesis with or without adding the four samples. Meanwhile, the anti-melanogenic activities of the four samples were not affected by whether the α-MSH was added in the medium or not and the added time of the α-MSH. On this basis, the 100 µg/mL EGCG, GCG, TFDG, or TSA did not affect the TYR catalytic activity but inhibited melanin formation partly through downregulating the melanocortin 1 receptor (MC1R), microphthalmia-associated transcription factor (MITF), and the TYR family. The downregulation abilities of catechins on the TYR family and MITF expression were stronger than those of dimers at both the transcription and translation levels, while the ability of dimers to downregulate the MC1R expression was stronger than that of catechins at both the transcription and translation levels to some extent. The results of molecular docking showed that these four samples could stably bind to MC1R protein. Taken together, this study offered molecular mechanisms for the anti-melanogenic activity of the EGCG, GCG, TFDG, and TSA, as potential effective components against the UV-induced tanning reactions, and a key target (MC1R) was identified.

Ginsenoside Re inhibits melanogenesis and melanoma growth by downregulating microphthalmia-associated transcription factor

Panax ginseng, also known as Korean ginseng, is a traditional remedy widely used in Asian countries. Its major active compounds are ginsenosides, specifically triterpenoid saponins. Among them, one notable ginsenoside called Re has shown various biological effects, including anti-cancer and anti-inflammatory properties. However, the potential beneficial effects of Re on melanogenesis and skin cancer remain poorly understood. To investigate this, we conducted a comprehensive study using biochemical assays, cell-based models, a zebrafish pigment formation model, and a tumor xenograft model. Our results revealed that Re effectively inhibited melanin biosynthesis in a dose-dependent manner by competitively inhibiting the activity of tyrosinase, an enzyme involved in melanin production. Moreover, Re significantly reduced the mRNA expression levels of microphthalmia-associated transcription factor (MITF), a key regulator of melanin biosynthesis and melanoma growth. Furthermore, Re decreased the protein expression of MITF and its target genes, including tyrosinase, TRP-1, and TRP-2, through a partially ubiquitin-dependent proteasomal degradation mechanism, mediated by the AKT and ERK signaling pathways. These findings indicate that Re exerts its hypopigmentary effects by directly inhibiting tyrosinase activity and suppressing its expression via MITF. Additionally, Re demonstrated inhibitory effects on skin melanoma growth and induced tumor vascular normalization in our in vivo experiments. This study represents the first evidence of Re-mediated inhibition of melanogenesis and skin melanoma, shedding light on the underlying mechanisms. These promising preclinical findings warrant further investigation to determine the suitability of Re as a natural agent for treating hyperpigmentation disorders and skin cancer.

Silver Carp (Hypophthalmichthys molitrix) Scale Collagen Peptides-1 (SCPs1) Inhibit Melanogenesis through Downregulation of the cAMP-CREB Signaling Pathway.

The mechanism of silver carp scale collagen peptides (SCPs1) on melanogenesis and its mechanism of action were examined in mouse melanoma cells (B16). The cell viability and effects of SCPs1 on intracellular tyrosinase (TYR) activity and melanin, reactive oxygen species (ROS), glutathione (GSH) and cyclic adenosine monophosphate (cAMP) content were examined. The regulatory mechanism of SCPs1 on the cAMP response element-binding protein (CREB) signaling pathway was analyzed. The cell viability of the SCPs1 group was >80% (0.01-1 mg/mL) and the inhibitory rate of SCPs1 on B16 cell melanin increased in a dose-dependent manner. The highest inhibitory rate of SCPs1 on melanin content reaching 80.24%. SCPs1 significantly increased the GSH content and decreased the tyrosinase activity, as well as the content of ROS and cAMP. Western blot analysis showed that SCPs1 significantly inhibited melanocortin-1 receptor (MC1R) expression and CREB phosphorylation in the cAMP-CREB signaling pathway, leading to downregulation of microphthalmia-associated transcription factor (MITF) and the expression of TYR, TYR-related protein-1 (TRP-1) and TRP-2. SCPs1 also inhibited the expression of MC1R, MITF, TYR, TRP-1 and TRP-2 at the transcriptional level. Taken together, SCPs1 inhibited melanin synthesis through the downregulation of the cAMP-CREB signaling pathway. Fish-derived collagen peptides could potentially be applied in skin whitening products.

Administration Of 30% Robusta Coffee (Coffea canephora) Silverskin Ethyl Acetate Fraction Cream Inhibited The Increase Of MITF Expression And Melanin Amount In The Skin Of Male Adult Guinea Pig (Cavia porcellus) Exposed To Ultraviolet B Ray

Background: Melanin is produced through melanogenesis which involves several molecular processes with microphthalmia-associated transcription factor (MITF) as the main regulator of melanin synthesis. Hyperpigmentation is one of aging sign that happens due to melanin buildup in the skin. Hyperpigmentation can be caused by many factors, and one of the most frequent cause is ultraviolet (UV) ray exposure. Robusta coffee silverskin is a thin layer on a green coffee bean that is detached from the bean through roasting process, and is a waste product of coffee production. However, coffee silverskin contains high amount of phenolic and flavonoid compounds, and is categorized as strong antioxidant. The purpose of this study was to prove that administration of 30% Robusta coffee silverskin ethyl acetate fraction cream inhibited the increase of MITF expression and melanin amount in the skin of male adult guinea pig exposed to UVB ray. Methods: This study used randomized post-test only control group design. Subjects used in this study were healthy male guinea pigs with age ranging from 3-4 months and average weight 300-350g. Total samples used in this study were 36 guinea pigs divided evenly into two groups, Group K that were only exposed to UVB ray, and Group P that were exposed to UVB ray and 30% Robusta coffee silverskin ethyl acetate fraction cream. Total UV ray used during two weeks were 390mJ/cm2. 30% Robusta coffee silverskin ethyl acetate fraction cream was applied twice a day on guinea pigs at the days they were not exposed to UVB ray, and at the days they were exposed to UVB ray, the cream was applied 20 minutes before and 4 hours after the exposure. MITF expression was examined under the microscope with MITF antibody kit, and melanin amount was examined with Masson-Fontana staining. Results: Result of the experiment showed higher MITF expression and melanin amount in the Group K. Comparison analysis with 2 independent samples t-test shows average MITF expression in the Group K and Group P 27.833 vs 15.422 % MITF, and 16.828 vs 7.822 % pixel melanin for the melanin amount. The differences between two variables were meaningful as the p value <0.001. Conclusions: Conclusion for this experiment is that 30% Robusta coffee silverskin ethyl acetate fraction cream inhibited the increase of MITF expression and melanin amount in adult male guinea pigs exposed to UVB.

Microphthalmia-Associated Transcription Factor: A Differentiation Marker in Uveal Melanoma.

Microphthalmia-associated transcription factor (MITF) is an important regulator of melanogenesis and melanocyte development. In cutaneous melanoma, MITF loss has been linked to an increased expression of stem cell markers, a shift in epithelial-to-mesenchymal transition (EMT)-related factors, and increased inflammation. We explored the role of MITF in Uveal Melanoma (UM) using a cohort of 64 patients enucleated at the Leiden University Medical Center. We analysed the relation between MITF expression and clinical, histopathological and genetic features of UM, as well as survival. We performed differential gene expression and gene set enrichment analysis using mRNA microarray data, comparing MITF-low with MITF-high UM. MITF expression was lower in heavily pigmented UM than in lightly pigmented UM (p = 0.003), which we confirmed by immunohistochemistry. Furthermore, MITF was significantly lower in UM with monosomy 3/BAP1 loss than in those with disomy 3/no BAP1 loss (p < 0.001) and with 8q gain/amplification 8q (p = 0.02). Spearman correlation analysis showed that a low MITF expression was associated with an increase in inflammatory markers, hallmark pathways involved in inflammation, and epithelial-mesenchymal transition. Similar to the situation in cutaneous melanoma, we propose that MITF loss in UM is related to de-differentiation to a less favourable EMT profile and inflammation.