Inhibition of α-melanocyte-stimulating hormone-induced melanogenesis and molecular mechanisms by polyphenol-enriched fraction of Tagetes erecta L. flower.

BACKGROUND: The pursuit for safe and efficacious skin-whitening agents has prompted a dedicated exploration of plant-derived compounds. Notably, Tagetes erecta L. flowers have been used as a medicinal extract and possessed in vitro mushroom tyrosinase activity. However, whether polyphenol-enriched fraction extracted from T. erecta L. flowers (TE) regulates melanogenesis within cellular and animal models has not yet been investigated. PURPOSE: This study aimed to investigate the effect of TE as a prospective inhibitor of melanogenesis. METHODS: Through advanced UPLC-QTof/MS analysis, the components of TE were analyzed. Anti-melanogenic effects of TE were evaluated in α-melanocyte-stimulating hormone (α-MSH)-stimulated B16F10 melanoma cells by measuring cell viability assay, extracellular and intracellular melanin biosynthesis, cyclic adenosine monophosphate (cAMP) production, and melanogenesis-related gene and protein expression. Zebrafish larvae were employed for in vivo studies, assessing both heart rate and melanogenesis. Furthermore, molecular docking analyses were employed to predict the interaction between TE components and the melanocortin 1 receptor (MC1R). Direct binding activity of TE components to MC1R was compared with [Nle4, d-Phe7]-MSH (NDP-MSH). RESULTS: TE was found to contain significant phenolic compounds such as patulitrin, quercetagetin, kaempferol, patuletin, and isorhamnetin. This study revealed that TE effectively inhibits melanin biosynthesis in both in vitro and in vivo models. This inhibition was attributed to interference of TE with the cAMP-cAMP response element-binding protein (CREB)-microphthalmia-associated transcription factor (MITF)-tyrosinase pathway, which plays a pivotal role in regulating melanogenesis. Importantly, TE exhibited the remarkable ability to curtail α-MSH-induced melanogenesis in zebrafish larvae without impacting heart rates. Molecular docking analyses predicted that the components of TE possibly interact with the melanocortin 1 receptor, suggesting their role as potential inhibitors of melanin biosynthesis. However, through the direct binding activity compared with NDP-MSH, any TE components did not directly bind to MC1R, suggesting that TE inhibits α-MSH-induced melanogenesis by inhibiting the cAMP-mediated intracellular signaling pathway. The assessment of anti-melanogenic activity, conducted both in vitro and in vivo, revealed that patulitrin and patuletin exhibited significant inhibitory effects on melanin formation, highlighting their potency as major contributors. DISCUSSION: This investigation demonstrated the considerable potential of TE as a natural remedy endowed with remarkable anti-melanogenic properties. The demonstrated capacity of TE to attenuate melanin production by modulating the cAMP-CREB-MITF-tyrosinase pathway underscores its central role in management of disorders associated with excessive pigmentation. Importantly, the implications of these findings extend to the cosmetics industry, where TE emerges as a prospective and valuable ingredient for the formulation of skin-whitening products. The elucidated interactions between TE components and MC1R not only provide insight into a potential mechanism of action but also elevate the significance of this study. In summary, this study not only contributes to our comprehension of pigmentation-related conditions but also firmly establishes TE as a secure and natural strategy for the regulation of melanin production. The innovative aspects of TE propel it into the forefront of potential interventions, marking a noteworthy advancement in the pursuit of effective and safe solutions for pigmentation disorders.

Brown Macroalgae Sargassum cristaefolium Extract Inhibits Melanin Production and Cellular Oxygen Stress in B16F10 Melanoma Cells.

The brown macroalgae Sargassum has been reported for its anti-UV and photoprotective potential for industrial applications. This study evaluated the melanin inhibition activity of Sargassum cristaefolium (SCE) ethanol extract. Melanogenesis inhibition by SCE was assessed in vitro with B16-F10 melanoma cell models and in silico against melanin regulatory proteins Tyrosinase (TYR) and Melanocortin 1 Receptor (MC1R). The regulatory properties evaluated were the melanin content, intracellular tyrosinase activity and cellular antioxidant activities. In addition, the bioactive compounds detected in SCE were subjected to molecular docking against TYR and MC1R. Based on the results, 150 µg/mL SCE effectively inhibited the production of melanin content and intracellular tyrosinase activity. Cellular tyrosinase activity was reduced by SCE-treated cells in a concentration-dependent manner. The results were comparable to the standard tyrosinase inhibitor kojic acid. In addition, SCE effectively decreased the intracellular reactive oxygen species (ROS) levels in B16-F10 cells. The antioxidant properties may also contribute to the inhibition of melanogenesis. In addition, LCMS UHPLC-HR-ESI-MS profiling detected 33 major compounds. The results based on in silico study revealed that the bioactive compound putative kaurenoic acid showed a strong binding affinity against TYR (-6.5 kcal/mol) and MC1R (-8.6 kcal/mol). However, further molecular analyses are needed to confirm the mechanism of SCE on melanin inhibition. Nevertheless, SCE is proposed as an anti-melanogenic and antioxidant agent, which could be further developed into cosmetic skin care products.

Sunlight exposure exerts immunomodulatory effects to reduce multiple sclerosis severity.

Multiple sclerosis (MS) disease risk is associated with reduced sun-exposure. This study assessed the relationship between measures of sun exposure (vitamin D [vitD], latitude) and MS severity in the setting of two multicenter cohort studies (nNationMS = 946, nBIONAT = 990). Additionally, effect-modification by medication and photosensitivity-associated MC1R variants was assessed. High serum vitD was associated with a reduced MS severity score (MSSS), reduced risk for relapses, and lower disability accumulation over time. Low latitude was associated with higher vitD, lower MSSS, fewer gadolinium-enhancing lesions, and lower disability accumulation. The association of latitude with disability was lacking in IFN-ß-treated patients. In carriers of MC1R:rs1805008(T), who reported increased sensitivity toward sunlight, lower latitude was associated with higher MRI activity, whereas for noncarriers there was less MRI activity at lower latitudes. In a further exploratory approach, the effect of ultraviolet (UV)-phototherapy on the transcriptome of immune cells of MS patients was assessed using samples from an earlier study. Phototherapy induced a vitD and type I IFN signature that was most apparent in monocytes but that could also be detected in B and T cells. In summary, our study suggests beneficial effects of sun exposure on established MS, as demonstrated by a correlative network between the three factors: Latitude, vitD, and disease severity. However, sun exposure might be detrimental for photosensitive patients. Furthermore, a direct induction of type I IFNs through sun exposure could be another mechanism of UV-mediated immune-modulation in MS.

25-Hydroxyvitamin D in Patients With Melanoma and Factors Associated With Inadequate Levels. / Niveles de 25-hidroxivitamina D en pacientes con melanoma y factores asociados con su insuficiencia.

INTRODUCTION AND OBJECTIVES: Patients with melanoma appear to take extreme sun-protection measures, which could influence 25-hydroxyvitamin D [25(OH)D] levels. The aim of this study was to measure 25(OH)D levels in patients with cutaneous melanoma and identify factors associated with inadequate levels. MATERIAL AND METHODS: Over a period of 1 year, we prospectively measured serum 25(OH)D in patients with cutaneous melanoma and used logistic regression analysis to identify environmental, phenotypic, and genotypic factors that were associated with insufficient and deficient levels. RESULTS: Of 215 patients analyzed, 8.8% had deficient 25(OH)D levels (<10ng/mL) and just 24.7% had normal levels. Insufficient levels (<30ng/mL) were associated with obesity (odds ratio [OR], 4.2; 95% confidence interval [CI], 1.3-13.3) and blood sampling in autumn/winter (OR, 2.1; 95% CI, 1.1-4). Deficient levels (<10ng/mL) were associated with obesity (OR, 7.1; 95% CI, 1.1-46.9), blood sampling in autumn/winter (OR, 9.0; 95% CI, 1.7-47.0), absence of freckles (OR, 5.4; 95% CI, 1.2-23.4), and, with marginal significance, the presence of fewer than 2 nonsynonymous melanocortin-1 receptor (MC1R) polymorphisms (OR, 5.0; 95% CI, 0.9-28.9). LIMITATIONS: Some factors related to 25(OH)D levels, such as food, were not included in the analyses. CONCLUSIONS: 25(OH)D levels should be monitored in patients with melanoma and the need for oral supplements should be contemplated where appropriate.

Regulation of melanocortin 1 receptor in allergic rhinitis in vitro and in vivo.

BACKGROUND: α-melanocyte-stimulating hormone (α-MSH) was shown to inhibit allergic airway inflammation and exert suppressive effects on human basophils. OBJECTIVE: This study aims to extend our current knowledge on the melanocortin 1 receptor (MC1R) expression in nasal tissue of patients with allergic rhinitis (AR) and functional effects of α-MSH in human basophils especially from patients with allergic rhinitis. METHODS: MC1R expression before and after nasal allergen provocation was studied in nasal mucosal tissue of AR patients and in a mouse model of allergic airway inflammation using immunofluorescence. In vitro regulation of the MC1R and CD203c surface expression on whole-blood basophils of patients with AR and controls was assessed with flow cytometry. Functional effects of α-MSH on isolated basophils were analysed regarding apoptosis with flow cytometry and chemotaxis using a Boyden chamber assay. RESULTS: We detected an accumulation of MC1R-positive basophils in nasal mucosa tissue of patients with AR 24 h after nasal allergen provocation. Such accumulation was not present in mucosa sections from healthy controls. In mice with allergic airway inflammation, we found a clear accumulation of MC1R-positive basophils in the nasal tissue compared to control mice. MC1R expression was inducible in AR patients and controls by stimulation with anti-IgE. α-MSH inhibited anti-IgE and grass pollen induced upregulation of CD203c, but had no effect on chemotaxis or apoptosis of basophils in vitro. CONCLUSIONS AND CLINICAL RELEVANCE: MC1R-positive basophils accumulate in the nasal mucosa of patients with AR after nasal allergen provocation. Since α-MSH suppresses proinflammatory effector functions in human basophils via the MC1R, it constitutes an interesting novel target for modulating the allergic inflammatory response.

An in Vitro and in Vivo Investigation of Bivalent Ligands That Display Preferential Binding and Functional Activity for Different Melanocortin Receptor Homodimers.

Pharmacological probes for the melanocortin receptors have been utilized for studying various disease states including cancer, sexual function disorders, Alzheimer's disease, social disorders, cachexia, and obesity. This study focused on the design and synthesis of bivalent ligands to target melanocortin receptor homodimers. Lead ligands increased binding affinity by 14- to 25-fold and increased cAMP signaling potency by 3- to 5-fold compared to their monovalent counterparts. Unexpectedly, different bivalent ligands showed preferences for particular melanocortin receptor subtypes depending on the linker that connected the binding scaffolds, suggesting structural differences between the various dimer subtypes. Homobivalent compound 12 possessed a functional profile that was unique from its monovalent counterpart providing evidence of the discrete effects of bivalent ligands. Lead compound 7 significantly decreased feeding in mice after intracerebroventricular administration. To the best of our knowledge, this is the first report of a melanocortin bivalent ligand's in vivo physiological effects.

Biased agonism as a novel strategy to harness the proresolving properties of melanocortin receptors without eliciting melanogenic effects.

There is a need for novel approaches to control pathologies with overexuberant inflammatory reactions. Targeting melanocortin (MC) receptors represents a promising therapy for obesity and chronic inflammation, but lack of selectivity and safety concerns limit development. A new way to increase selectivity of biological effects entails the identification of biased agonists. In this study, we characterize the small molecule AP1189 as a biased agonist at receptors MC1 and MC3. Although not provoking canonical cAMP generation, AP1189 addition to MC1 or MC3, but not empty vector, transfected HEK293 cells caused ERK1/2 phosphorylation, a signaling responsible for the proefferocytic effect evoked in mouse primary macrophages. Added to macrophage cultures, AP1189 reduced cytokine release, an effect reliant on both MC1 and MC3 as evident from the use of Mc1r(-/-) and Mc3r(-/-) macrophages. No melanogenesis was induced by AP1189 in B16-F10 melanocytes. In vivo, oral AP1189 elicited anti-inflammatory actions in peritonitis and, upon administration at the peak of inflammation, accelerated the resolution phase by ∼3-fold. Finally, given the clinical efficacy of adrenocorticotropin in joint diseases, AP1189 was tested in experimental inflammatory arthritis, where this biased agonist afforded significant reduction of macroscopic and histological parameters of joint disruption. These proof-of-concept analyses with AP1189, an active oral anti-inflammatory and resolution-promoting compound, indicate that biased agonism at MC receptors is an innovative, viable approach to yield novel anti-inflammatory molecules endowed with a more favorable safety profile.

Melanocortin 1 receptor-signaling deficiency results in an articular cartilage phenotype and accelerates pathogenesis of surgically induced murine osteoarthritis.

Proopiomelanocortin-derived peptides exert pleiotropic effects via binding to melanocortin receptors (MCR). MCR-subtypes have been detected in cartilage and bone and mediate an increasing number of effects in diathrodial joints. This study aims to determine the role of MC1-receptors (MC1) in joint physiology and pathogenesis of osteoarthritis (OA) using MC1-signaling deficient mice (Mc1re/e). OA was surgically induced in Mc1re/e and wild-type (WT) mice by transection of the medial meniscotibial ligament. Histomorphometry of Safranin O stained articular cartilage was performed with non-operated controls (11 weeks and 6 months) and 4/8 weeks past surgery. µCT-analysis for assessing epiphyseal bone architecture was performed as a longitudinal study at 4/8 weeks after OA-induction. Collagen II, ICAM-1 and MC1 expression was analysed by immunohistochemistry. Mc1re/e mice display less Safranin O and collagen II stained articular cartilage area compared to WT prior to OA-induction without signs of spontaneous cartilage surface erosion. This MC1-signaling deficiency related cartilage phenotype persisted in 6 month animals. At 4/8 weeks after OA-induction cartilage erosions were increased in Mc1re/e knees paralleled by weaker collagen II staining. Prior to OA-induction, Mc1re/e mice do not differ from WT with respect to bone parameters. During OA, Mc1re/e mice developed more osteophytes and had higher epiphyseal bone density and mass. Trabecular thickness was increased while concomitantly trabecular separation was decreased in Mc1re/e mice. Numbers of ICAM-positive chondrocytes were equal in non-operated 11 weeks Mc1re/e and WT whereas number of positive chondrocytes decreased during OA-progression. Unchallenged Mc1re/e mice display smaller articular cartilage covered area without OA-related surface erosions indicating that MC1-signaling is critical for proper cartilage matrix integrity and formation. When challenged with OA, Mc1re/e mice develop a more severe OA-pathology. Our data suggest that MC1-signaling protects against cartilage degradation and subchondral bone sclerosis in OA indicating a beneficial role of the POMC system in joint pathophysiology.

Minireview: Central Sirt1 regulates energy balance via the melanocortin system and alternate pathways.

In developed nations, the prevalence of obesity and its associated comorbidities continue to prevail despite the availability of numerous treatment strategies. Accumulating evidence suggests that multiple inputs from the periphery and within the brain act in concert to maintain energy metabolism at a constant rate. At the central level, the hypothalamus is the primary component of the nervous system that interprets adiposity or nutrient-related inputs; it delivers hormonal and behavioral responses with the ultimate purpose of regulating energy intake and energy consumption. At the molecular level, enzymes called nutrient energy sensors mediate metabolic responses of those tissues involved in energy balance ( 1 ). Two key energy/nutrient sensors, mammalian target of rapamycin and AMP-activated kinase, are involved in the control of food intake in the hypothalamus as well as in peripheral tissues ( 2 , 3 ). The third more recently discovered nutrient sensor, Sirtuin1 (Sirt1), a nicotinamide adenine dinucleotide-dependent deacetylase, functions to maintain whole-body energy homeostasis. Several studies have highlighted a role for both peripheral and central Sirt1 in regulating body metabolism, but its central role is still heavily debated. Owing to the opaqueness of central Sirt1's role in energy balance are its cell-specific functions. Because of its robust central expression, targeting cell-specific downstream mediators of Sirt1 signaling may help to combat obesity. However, when placed in the context of a physiologically relevant model, there is compelling evidence that central Sirt1 inhibition in itself is sufficient to promote negative energy balance in both the lean and diet-induced obese state.

Alpha-melanocyte stimulating hormone ameliorates disease activity in an induced murine lupus-like model.

Alpha-melanocyte stimulating hormone (α-MSH) is a neuropeptide exhibiting anti-inflammatory activity in experimental models of autoimmune diseases. However, no studies thus far have examined the effects of α-MSH on systemic lupus erythematosus (SLE). This study aimed to determine the effects of an α-MSH agonist in induced murine lupus. Here we employed female Balb/cAn mice in which lupus was induced by pristane. Groups of lupus animals were treated daily with the α-MSH analogue [Nle4, DPhe7]-α-MSH (NDP-MSH) (1·25 mg/kg) injected intraperitoneally or saline for 180 days. Normal animals comprised the control group. Arthritis incidence, plasma immunoglobulin (Ig)G isotypes, anti-nuclear antibodies (ANA) and plasma cytokines were evaluated. Renal function was assessed by proteinuria and histopathological lesion. Glomerular levels of IgG, α-smooth muscle actin (α-SMA), inducible nitric oxide synthase (iNOS), C3, CD3, melanocortin receptors (MCR)1, corticotrophin-releasing factor (CRF) and α-MSH was estimated by immunohistochemistry. When compared with normal controls, lupus animals exhibited increased arthritis, IgG levels, ANA, interleukin (IL)-6, IL-10, proteinuria and mesangial cell proliferation together with glomerular expression of α-SMA and iNOS. Glomerular expression of MCR1 was reduced in lupus animals. NDP-MSH treatment reduced arthritis scores by 70% and also diminished IgG1 and IgG2a levels and ANA incidence. In the glomerulus, NDP-MSH treatment reduced cellularity by 50% together with reducing IgG deposits, and expression levels of α-SMA, iNOS and CRF were also all decreased. Taken together, our results suggest for the first time that α-MSH treatment improves several parameters of SLE disease activity in mice, and indicate that this hormone is an interesting potential future treatment option.

Arthrophytum scoparium inhibits melanogenesis through the down-regulation of tyrosinase and melanogenic gene expressions in B16 melanoma cells.

Melanin performs a crucial role in protecting the skin against harmful ultraviolet light. However, hyperpigmentation may lead to aesthetic problems and disorders such as solar lentigines (SL), melasma, postinflammatory hyperpigmentation and even melanoma. Arthrophytum scoparium grows in the desert in the North African region, and given this type of environment, A. scoparium exhibits adaptations for storing water and produces useful bioactive factors. In this study, the effect of A. scoparium ethanol extract (ASEE) on melanogenesis regulation in B16 murine melanoma cells was investigated. Cells treated with 0.017% (w/v) ASEE showed a significant inhibition of melanin biosynthesis in a time-dependent manner without cytotoxicity. To clarify the mechanism behind the ASEE-treated melanogenesis regulation, the expressions of tyrosinase enzyme and melanogenesis-related genes were determined. Results showed that the expression of tyrosinase enzyme was significantly decreased and Tyr, Trp-1, Mitf and Mc1R mRNA expressions were significantly down-regulated. LC-ESI-TOF-MS analysis of the extract identified the presence of six phenolic compounds: coumaric acid, cinnamic acid, chrysoeriol, cyanidin, catechol and caffeoylquinic acid. The melanogenesis inhibitory effect of ASEE may therefore be attributed to its catechol and tetrahydroisoquinoline derivative content. We report here that ASEE can inhibit melanogenesis in a time-dependent manner by decreasing the tyrosinase protein and Tyr, Trp-1, Mitf and Mc1R mRNA expressions. This is the first report on the antimelanogenesis effect of A. scoparium and on its potential as a whitening agent.

BacMam system for FRET-based cAMP sensor expression in studies of melanocortin MC1 receptor activation.

Cyclic adenosine monophosphate (cAMP) is a second messenger of many G-protein-coupled receptors (GPCRs) and a useful readout molecule to estimate the biological activity of various GPCR-specific agents. Here we report the development and use of a Förster resonance energy transfer (FRET) biosensor for cAMP (Epac2-camps) combined with a baculovirus-based BacMam transduction system. The constructed BacMam-Epac2-camps viral transduction system is a simple and robust tool for ligand screening at the second-messenger level in a variety of mammalian cell lines. The level of biosensor protein expression can easily be adjusted in a dose-dependent manner depending on the multiplicity of viral infection. For setting up the assay, we used a B16F10 murine melanoma cell line with endogenous expression of melanocortin-1 receptor (MC(1)R). The receptor activation was characterized by a set of MC(1)R full and partial agonists. Bivalent ions Ca(2+) as well as Mg(2+) modulated ligand potencies, whereas the effect was ligand and ion specific. Results obtained for MC(1)R indicate that the BacMam-Epac2-camps system may also be applicable for studying the activation of other GPCRs and may be implemented in routine analysis as well as in high-throughput screening.

Melanocortin-1 receptor-mediated signalling pathways activated by NDP-MSH and HBD3 ligands.

Binding of melanocortin peptide agonists to the melanocortin-1 receptor of melanocytes results in eumelanin production, whereas binding of the agouti signalling protein inverse agonist results in pheomelanin synthesis. Recently, a novel melanocortin-1 receptor ligand was reported. A ß-defensin gene mutation was found to be responsible for black coat colour in domestic dogs. Notably, the human equivalent, ß-defensin 3, was found to bind with high affinity to the melanocortin-1 receptor; however, the action of ß-defensin as an agonist or antagonist was unknown. Here, we use in vitro assays to show that ß-defensin 3 is able to act as a weak partial agonist for cAMP signalling in human embryonic kidney (HEK) cells expressing human melanocortin-1 receptor. ß-defensin 3 is also able to activate MAPK signalling in HEK cells stably expressing either wild type or variant melanocortin-1 receptors. We suggest that ß-defensin 3 may be a novel melanocortin-1 receptor agonist involved in regulating melanocyte responses in humans.

Neonatal blue light phototherapy and melanocytic nevi: a twin study.

BACKGROUND: Neonatal blue light phototherapy (NBLP) has been widely and successfully used for the treatment of neonatal jaundice to reduce the plasma concentration of bilirubin and, hence, to prevent kernicterus. Only a few and controversial data are available in the literature as to how NBLP influences melanocytic nevus development. OBJECTIVE: Our goal was to conduct a twin study with the aim of better understanding the role of NBLP in melanocytic nevus development. We also investigated the roles of other environmental and constitutional factors in nevus formation. METHODS: Fifty-nine monozygotic and dizygotic twins were included in this cross-sectional study. One of the twin members received NBLP, and the other did not. A whole-body skin examination was performed to determine the density of melanocytic skin lesions. The prevalence of benign pigmented uveal lesions was evaluated during a detailed ophthalmologic examination. A standardized questionnaire was used to assess data relating to constitutional, sun-exposure, and other variables. To search for possible gene-environmental interactions involved in the appearance of pigmented lesions, the melanocortin 1 receptor variants and the I439V polymorphism of histidine ammonia-lyase genes were also determined in the enrolled twins. RESULTS: NBLP was associated with a significantly higher prevalence of both cutaneous and uveal melanocytic lesions. No association was found between the examined gene polymorphisms and the number of pigmented alterations in the examined study group. CONCLUSIONS: Our data suggest that NBLP could well be a risk factor for melanocytic nevus development. Phototherapy with blue-light lamps is a standard and essential therapeutic modality in neonatal care; therefore, additional in vivo and in vitro studies are necessary to establish its potential long-term adverse effects.

Antioxidant and antimelanogenic behaviors of Paeonia suffruticosa.

Antioxidant properties of eight Paeonia suffruticosa (Ps) extracts (Ps-1 to Ps-8) were evaluated. The respective half maximally effective concentration (EC(50)) values of Ps-1 ~ 8 were 10.0, 9.8, 63.6, >100, 3.8, 85.1, 6.9, and 0.7 µg/ml for 1,1-diphenyl-2-picrylhydrazyl radical (DPPH·) radical scavenging efficiency and 22.9, 11.4, 53.1, >100, 7.5, 97.6, 43.7, 4.2 µg/ml for 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS·(+)) radical scavenging capacity. The Ps-8 exhibited high free radical scavenging capacity, ion-chelating ability, reducing power, and inhibition of lipid peroxidation, which may have been attributable to its abundant phenolic and flavonoid content. In Hs68 and B16 cells treated with 100 µg/ml Ps-1, Ps-3, Ps-4 and Ps-6, expressions of toxic activities were lower than those in cells treated with arbutin and ascorbic acid. The antimelanogenesis properties were also tested in B16 cells. Extract Ps-1, and particularly extract Ps-6, considerably inhibited cellular tyrosinase and 3,4-dihydroxyphenylalanine (DOPA) oxidase activity and also reduced melanin content in B16 cells by down-expression of melanocortin-1 receptor (MC1R), microphthalmia-associated transcription factor (MITF), tyrosinase, and tyrosinase-related proteins-1 (TRP-1). The results suggest that P. suffruticosa extracts have antioxidant and antimelanogenesis activities with potential applications in cosmetic materials or food additives.

Comprehensive field synopsis and systematic meta-analyses of genetic association studies in cutaneous melanoma.

BACKGROUND: Although genetic studies have reported a number of loci associated with cutaneous melanoma (CM) risk, a comprehensive synopsis of genetic association studies published in the field and systematic meta-analysis for all eligible polymorphisms have not been reported. METHODS: We systematically annotated data from all genetic association studies published in the CM field (n = 145), including data from genome-wide association studies (GWAS), and performed random-effects meta-analyses across all eligible polymorphisms on the basis of four or more independent case-control datasets in the main analyses. Supplementary analyses of three available datasets derived from GWAS and GWAS-replication studies were also done. Nominally statistically significant associations between polymorphisms and CM were graded for the strength of epidemiological evidence on the basis of the Human Genome Epidemiology Network Venice criteria. All statistical tests were two-sided. RESULTS: Forty-two polymorphisms across 18 independent loci evaluated in four or more datasets including candidate gene studies and available GWAS data were subjected to meta-analysis. Eight loci were identified in the main meta-analyses as being associated with a risk of CM (P < .05) of which four loci showed a genome-wide statistically significant association (P < 1 × 10(-7)), including 16q24.3 (MC1R), 20q11.22 (MYH7B/PIGU/ASIP), 11q14.3 (TYR), and 5p13.2 (SLC45A2). Grading of the cumulative evidence by the Venice criteria suggested strong epidemiological credibility for all four loci with genome-wide statistical significance and one additional gene at 9p23 (TYRP1). In the supplementary meta-analyses, a locus at 9p21.3 (CDKN2A/MTAP) reached genome-wide statistical significance with CM and had strong epidemiological credibility. CONCLUSIONS: To the best of our knowledge, this is the first comprehensive field synopsis and systematic meta-analysis to identify genes associated with an increased susceptibility to CM.

Ov-16 [4-(3,4-dihydroxybenzoyloxymethyl)phenyl-O-ß-D-glucopyranoside] inhibits melanin synthesis by regulating expressions of melanogenesis-regulated gene and protein.

Ov-16 (4-(3,4-dihydroxybenzoyloxymethyl)phenyl-O-ß-D-glucopyranoside), a polyphenolic glycoside that is isolated from oregano (Origanum vulgare L.), can scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals. This investigation is the first to study in detail the hypopigmentary properties of Ov-16. It demonstrates that 0-1000 µg/ml Ov-16 inhibits the activity of mushroom tyrosinase (Tyr) in a concentration-dependent manner. The inhibitionary Tyr kinetics of Ov-16 towards the oxidation of L-DOPA was found to be uncompetitive. Following the treatment of human skin premalignant kerationcyte HaCaT cells, human skin fibroblast Hs68 cells and mice melanoma B16 cells with Ov-16 (0-100 µg/ml), cell viability was >98%, suggesting that Ov-16 is non-toxic. Ov-16 can reduce cellular Tyr activity, DOPA oxidase activity and melanin synthesis in B16 cells that are stimulated by the α-melanocyte-stimulating hormone (α-MSH). Moreover, Ov-16 inhibited the production of melanin in Streptomyces bikiniensis without affecting the growth of the microorganism. The treatment of B16 cells with Ov-16 considerably reduced the gene expressions of melanocortin-1 receptor (Mc1r), microphthalmia-associated transcription factor (Mitf), Tyr, tyrosinase-related proteins-2 (Trp-2) and Trp-1, as determined by RT-PCR. The expressions of Mc1r, Mift, Tyr, Trp-2 and TrpP-1 protein in Ov-16-treated B16 cells were also significantly reduced, as determined by western blotting and fluorescent staining analysis. These results suggest that Ov-16 exhibits hypopigmentary performance.

Glutathione S-transferase M1 (GSTM1) genotype but not GSTT1 or MC1R genotype influences erythemal sensitivity to narrow band (TL-01) UVB phototherapy.

OBJECTIVES: Although a majority of psoriasis patients respond to treatment with narrow band ultraviolet B radiation (TL-01) phototherapy, it is currently not possible to predict erythemal sensitivity, or to identify treatment responders. A variety of antioxidant enzymes, including the polymorphic glutathione S-transferase GSTM1 and GSTT1 genes, protect the cell from UVR-induced oxidative challenge. GSTM1 and GSTT1 are deleted in approximately 50 and 20% of the Caucasian population, respectively, and GST null genotype has been associated with increased sunburn sensitivity and reduced minimal erythemal dose (MED) after broadband UVR exposure in healthy volunteers and with susceptibility to skin cancer. Another polymorphic determinant of UVR sensitivity is the melanocortin 1 receptor (MC1R), which protects cells from UVR-induced apoptosis and photodamage. Our aim was therefore to investigate whether GST or MC1R genotype influenced erythemal sensitivity to narrow band (TL-01) ultraviolet B radiation phototherapy in patients with psoriasis. METHODS: We used TaqMan quantitative gene copy and allelic discrimination assays to determine GST and MC1R genotypes, and looked for possible associations between genotype and threshold erythemal sensitivity (MED) and treatment outcomes in patients with psoriasis (n=256). RESULTS: We showed that GSTM1 genotype, but not GSTT1 or MC1R genotype influences erythemal sensitivity to TL-01 phototherapy, with a significantly lower MED observed in GSTM1 null individuals [χ(2 d.f.)=8.862, P=0.012]. None of the genotypes studied were associated with TL-01 treatment outcomes or relapse rates. CONCLUSION: GSTM1 genotype may have clinical utilityin the prediction of photosensitivity and/or in identifying patients at increased risk of treatment-related side effects.

Inhibitory effect of Elephantopus mollis H.B. and K. extract on melanogenesis in B16 murine melanoma cells by downregulating microphthalmia-associated transcription factor expression.

In this study, the inhibitory effect of Elephantopus mollis H.B. and K. extract on melanogenesis in B16 murine melanoma cells was examined and possible mechanisms were elucidated. The melanin content in B16 cells decreased when they were treated with E. mollis extract. Inhibition was accompanied by reduced expression of tyrosinase (TYR) and tyrosinase-related protein 1 (TRP1). Furthermore, the expression level of microphthalmia-associated transcription factor (MITF), a major transcriptional regulator of genes encoding melanogenic enzymes such as Tyr and Trp1, decreased as assessed by western blotting and quantitative reverse transcriptase polymerase chain reaction (RT-PCR). These results suggest that E. mollis extract reduces melanogenesis by downregulating Mitf expression, leading to reduced expression of Tyr and Trp1. In addition, melanocortin-1 receptor (MC1R) expression was downregulated by E. mollis extract, suggesting desensitization to α-melanocyte-stimulating hormone (α-MSH) of cells treated with the extract.