Skin melanocytes: biology and development

Enhancement strategies for transdermal drug delivery systems: current trends and applications

Transdermal drug delivery systems have become an intriguing research topic in pharmaceutical technology area and one of the most frequently developed pharmaceutical products in global market. The use of these systems can overcome associated drawbacks of other delivery routes, such as oral and parenteral. The authors will review current trends, and future applications of transdermal technologies, with specific focus on providing a comprehensive understanding of transdermal drug delivery systems and enhancement strategies. This article will initially discuss each transdermal enhancement method used in the development of first-generation transdermal products. These methods include drug/vehicle interactions, vesicles and particles, stratum corneum modification, energy-driven methods and stratum corneum bypassing techniques. Through suitable design and implementation of active stratum corneum bypassing methods, notably microneedle technology, transdermal delivery systems have been shown to deliver both low and high molecular weight drugs. Microneedle technology platforms have proven themselves to be more versatile than other transdermal systems with opportunities for intradermal delivery of drugs/biotherapeutics and therapeutic drug monitoring. These have shown that microneedles have been a prospective strategy for improving transdermal delivery systems.

Effects of Electromagnetic Waves with LTE and 5G Bandwidth on the Skin Pigmentation In Vitro

With the rapid growth of wireless communication devices, the influences of electromagnetic fields (EMF) on human health are gathering increasing attention. Since the skin is the largest organ of the body and is located at the outermost layer, it is considered a major target for the health effects of EMF. Skin pigmentation represents one of the most frequent symptoms caused by various non-ionizing radiations, including ultraviolet radiation, blue light, infrared, and extremely low frequency (ELF). Here, we investigated the effects of EMFs with long-term evolution (LTE, 1.762 GHz) and 5G (28 GHz) bandwidth on skin pigmentation in vitro. Murine and Human melanoma cells (B16F10 and MNT-1) were exposed to either LTE or 5G for 4 h per day, which is considered the upper bound of average smartphone use time. It was shown that neither LTE nor 5G exposure induced significant effects on cell viability or pigmentation. The dendrites of MNT-1 were neither lengthened nor regressed after EMF exposure. Skin pigmentation effects of EMFs were further examined in the human keratinocyte cell line (MNT-1-HaCaT) co-culture system, which confirmed the absence of significant hyper-pigmentation effects of LTE and 5G EMFs. Lastly, MelanoDerm™, a 3D pigmented human epidermis model, was irradiated with LTE (1.762 GHz) or 5G (28 GHz), and image analysis and special staining were performed. No changes in the brightness of MelanoDerm™ tissues were observed in LTE- or 5G-exposed tissues, except for only minimal changes in the size of melanocytes. Collectively, these results imply that exposure to LTE and 5G EMFs may not affect melanin synthesis or skin pigmentation under normal smartphone use condition.

Molecular and Biochemical Basis of Fluoroquinolones-Induced Phototoxicity-The Study of Antioxidant System in Human Melanocytes Exposed to UV-A Radiation

Phototoxicity of fluoroquinolones is connected with oxidative stress induction. Lomefloxacin (8-halogenated derivative) is considered the most phototoxic fluoroquinolone and moxifloxacin (8-methoxy derivative) the least. Melanin pigment may protect cells from oxidative damage. On the other hand, fluoroquinolone–melanin binding may lead to accumulation of drugs and increase their toxicity to skin. The study aimed to examine the antioxidant defense system status in normal melanocytes treated with lomefloxacin and moxifloxacin and exposed to UV-A radiation. The obtained results demonstrated that UV-A radiation enhanced only the lomefloxacin-induced cytotoxic effect in tested cells. It was found that fluoroquinolones alone and with UV-A radiation decreased superoxide dismutase (SOD) activity and SOD1 expression. UV-A radiation enhanced the impact of moxifloxacin on hydrogen peroxide-scavenging enzymes. In turn, lomefloxacin alone increased the activity and the expression of catalase (CAT) and glutathione peroxidase (GPx), whereas UV-A radiation significantly modified the effects of drugs on these enzymes. Taken together, both analyzed fluoroquinolones induced oxidative stress in melanocytes, however, the molecular and biochemical studies indicated the miscellaneous mechanisms for the tested drugs. The variability in phototoxic potential between lomefloxacin and moxifloxacin may result from different effects on the antioxidant enzymes.

A Series of RET Fusion Spitz Neoplasms With Plaque-Like Silhouette and Dyscohesive Nesting of Epithelioid Melanocytes

ABSTRACT

Two distinct studies have shown that RET fusions are found in 3%-4% of Spitz neoplasms. RET fusions have been well described in papillary thyroid cancer, non-small-cell lung cancer, breast cancer, and soft-tissue mesenchymal tumors as well as some other neoplasms. However, there are no comprehensive descriptions to date of the characteristic morphologic, clinical, or genomic findings in RET fusion Spitz neoplasms. In this study, we identified 5 cases of RET fusion Spitz neoplasms. These tumors showed characteristic morphologic features which included plaque-like silhouette and monotonous epithelioid cytology with expansile and dyscohesive nesting. Four of 5 patients including 1 diagnosed as Spitz melanoma had clinical follow-up all of which was uneventful. Furthermore, we describe the genomic sequences in 4 of these cases, 2 of which have previously described KIF5B-RET fusion and 2 of which had a novel LMNA-RET fusion. We believe this report significantly contributes to our current knowledge regarding Spitz neoplasms and describes characteristics features which can help with recognition of the RET subgroup of Spitz.

Exosomes: Emerging Diagnostic and Therapeutic Targets in Cutaneous Diseases

Skin is the largest human organ and is continuously exposed to various exogenous and endogenous trigger factors affecting body homeostasis. A number of mechanisms, including genetic, inflammatory and autoimmune ones, have been implicated in the pathogenesis of cutaneous diseases. Recently, there has been considerable interest in the role that extracellular vesicles, particularly exosomes, play in human diseases, through their modulation of multiple signaling pathways. Exosomes are nano-sized vesicles secreted by all cell types. They function as cargo carriers shuttling proteins, nucleic acids, lipids etc., thus impacting the cell-cell communications and transfer of vital information/moieties critical for skin homeostasis and disease pathogenesis. This review summarizes the available knowledge on how exosomes affect pathogenesis of cutaneous diseases, and highlights their potential as future targets for the therapy of various skin diseases.

Effects of Fluoride Exposure on Primary Human Melanocytes from Dark and Light Skin

Fluoride exposure has adverse effects on human health that have been studied in vitro in cell culture systems. Melanocytes are the melanin pigment-producing cells that have a significant role in the regulation of the process of melanogenesis, which provides several health benefits. Melanocytes are present in the oral cavity, skin, brain, lungs, hair, and eyes. However, to date, there has been no study on the effects of fluoride exposure on melanocytes. Hence, in the current study, we have studied the effects of sodium fluoride (NaF) exposure on neonatal human epidermal melanocytes (HEMn) derived from two different skin phototypes, lightly pigmented (LP) and darkly pigmented (DP). We have assessed the impact of a 24 h and 72 h NaF exposure on metabolic activity and membrane integrity of these cells. In addition, we have evaluated whether NaF exposure might have any impact on the physiological functions of melanocytes associated with the production of melanin, which is regulated by activity of the enzyme tyrosinase. We have also assessed if NaF exposure might induce any oxidative stress in LP and DP melanocytes, by evaluation of production of reactive oxygen species (ROS) and measurement of mitochondrial membrane potential (MMP) levels. Our results showed that HEMn-LP cells showed a higher sensitivity to NaF cytotoxicity than HEMn-DP cells, with significant cytotoxicity at concentrations >1 mM, while concentration range 0.25–1 mM were nontoxic and did not lead to oxidative stress, and also did not alter the levels of intracellular melanin or cellular tyrosinase activity, indicating that treatment up to 1 mM NaF is generally safe to melanocytes from both pigmentation phototypes.

Application of adipose-derived stem cells in photoaging: basic science and literature review

Photoaging is mainly induced by continuous exposure to sun light, causing multiple unwanted skin characters and accelerating skin aging. Adipose-derived stem cells(ADSCs) are promising in supporting skin repair because of their significant antioxidant capacity and strong proliferation, differentiation, and migration ability, as well as their enriched secretome containing various growth factors and cytokines. The identification of the mechanisms by which ADSCs perform these functions for photoaging has great potential to explore therapeutic applications and combat skin aging. We also review the basic mechanisms of UV-induced skin aging and recent improvement in pre-clinical applications of ADSCs associated with photoaging. Results showed that ADSCs are potential to address photoaging problem and might treat skin cancer. Compared with ADSCs alone, the secretome-based approaches and different preconditionings of ADSCs are more promising to overcome the current limitations and enhance the anti-photoaging capacity.

A Framework of Major Tumor-Promoting Signal Transduction Pathways Implicated in Melanoma-Fibroblast Dialogue

Simple Summary

Melanoma cells reside in a complex stromal microenvironment, which is a critical component of disease onset and progression. Mesenchymal or fibroblastic cell type are the most abundant cellular element of tumor stroma. Factors secreted by melanoma cells can activate non-malignant associated fibroblasts to become melanoma associate fibroblasts (MAFs). MAFs promote tumorigenic features by remodeling the extracellular matrix, supporting tumor cells proliferation, neo-angiogenesis and drug resistance. Additionally, environmental factors may contribute to the acquisition of pro-tumorigenic phenotype of fibroblasts. Overall, in melanoma, perturbed tissue homeostasis contributes to modulation of major oncogenic intracellular signaling pathways not only in tumor cells but also in neighboring cells. Thus, targeted molecular therapies need to be considered from the reciprocal point of view of melanoma and stromal cells.

Abstract

The development of a modified stromal microenvironment in response to neoplastic onset is a common feature of many tumors including cutaneous melanoma. At all stages, melanoma cells are embedded in a complex tissue composed by extracellular matrix components and several different cell populations. Thus, melanomagenesis is not only driven by malignant melanocytes, but also by the altered communication between melanocytes and non-malignant cell populations, including fibroblasts, endothelial and immune cells. In particular, cancer-associated fibroblasts (CAFs), also referred as melanoma-associated fibroblasts (MAFs) in the case of melanoma, are the most abundant stromal cells and play a significant contextual role in melanoma initiation, progression and metastasis. As a result of dynamic intercellular molecular dialogue between tumor and the stroma, non-neoplastic cells gain specific phenotypes and functions that are pro-tumorigenic. Targeting MAFs is thus considered a promising avenue to improve melanoma therapy. Growing evidence demonstrates that aberrant regulation of oncogenic signaling is not restricted to transformed cells but also occurs in MAFs. However, in some cases, signaling pathways present opposite regulation in melanoma and surrounding area, suggesting that therapeutic strategies need to carefully consider the tumor–stroma equilibrium. In this novel review, we analyze four major signaling pathways implicated in melanomagenesis, TGF-β, MAPK, Wnt/β-catenin and Hyppo signaling, from the complementary point of view of tumor cells and the microenvironment.

Primary Ciliary Signaling in the Skin-Contribution to Wound Healing and Scarring

Primary cilia (PC) are solitary, post-mitotic, microtubule-based, and membrane-covered protrusions that are found on almost every mammalian cell. PC are specialized cellular sensory organelles that transmit environmental information to the cell. Signaling through PC is involved in the regulation of a variety of cellular processes, including proliferation, differentiation, and migration. Conversely, defective, or abnormal PC signaling can contribute to the development of various pathological conditions. Our knowledge of the role of PC in organ development and function is largely based on ciliopathies, a family of genetic disorders with mutations affecting the structure and function of PC. In this review, we focus on the role of PC in their major signaling pathways active in skin cells, and their contribution to wound healing and scarring. To provide comprehensive insights into the current understanding of PC functions, we have collected data available in the literature, including evidence across cell types, tissues, and animal species. We conclude that PC are underappreciated subcellular organelles that significantly contribute to both physiological and pathological processes of the skin development and wound healing. Thus, PC assembly and disassembly and PC signaling may serve as attractive targets for antifibrotic and antiscarring therapies.

Immunotherapies in cutaneous pathologies: an overview

Skin is a vital protective organ, the main role of which is to provide a physical barrier and to prevent the entry of pathogens. Various pathologies, such as atopic dermatitis (AD), psoriasis (PSO), or skin cancers, can affect the skin, and all show a high and increasing prevalence. Many antibodies are currently used in the treatment of these diseases. However, various studies are underway for the development of new biologics directed against specific targets. In this review, we describe current biologics used in skin pathologies as well as antibodies in development. We also discuss various immunotherapy examples that use new delivery technologies, such as microneedle patch, nanoparticles (NPs), liposomes, or gel formulation.

Inhibitory insights of strawberry (Fragaria × ananassa var. Seolhyang) root extract on tyrosinase activity using computational and in vitro analysis

The strawberry (Fragaria × ananassa var. seolhyang) is commonly used as fruit but medicinal importance for the non-edible roots which contained a pool of bioactive compounds are not yet studied against tyrosinase inhibition. This study demonstrates the potential of bioactive compounds in root and rhizome of strawberry against tyrosinase inhibition using in silico and in vitro approaches. ADMET profiling and molecular docking analysis show druglikeness for the major bioactive compounds in strawberry root extract (SRE), i.e. procyanidin, procyanidin trimer, kaempferol 3-O-(4-O-p-coumaroyl)-glucoside, neochlorogenic acid, procyanidin tetramer, and quercetin-3-O-pentoside, and docking score between -7.8 to -6.3 kcal/mol with tyrosinase, respectively. Also, these docked complexes exhibit substantial stability contributed by strong hydrogen bonding, hydrophobic interactions, and polar interactions in 100 ns molecular dynamics simulation; further supported by essential dynamics and dynamic cross-correlation matrix analysis. Also, in vitro functional assays support in silico predicted results in terms of substantial cytoprotective and cellular antioxidant potential in Raw 264.7 macrophages challenged by H₂O₂ as well as non-significant toxicity in zebrafish. SRE exhibits the lowest (5.8%) and highest (42.8%) inhibition of tyrosinase at 100 and 500 μg/ml concentrations, respectively. These results advocated functional properties and tyrosinase inhibition potential of SRE; and hence, SRE can be used in medicinal or cosmetic applications.

Enhancement of the antioxidant and skin permeation properties of eugenol by the esterification of eugenol to new derivatives

The aim of the study was to determine the antioxidant activity and assess the lipophilicity and skin penetration of eugenyl chloroacetate (EChA), eugenyl dichloroacetate (EDChA), and eugenyl trichloroacetate (ETChA). Identification of the obtained products was based on gas chromatography (GC), infrared spectroscopy (FTIR/ATR), gas chromatography coupled with mass spectrometry (GC-MS), and the analysis of 13C-NMR and 1H-NMR spectra. The antioxidative capacity of the derivatives obtained was determined by the DPPH free radical reduction method, while the octanol/water partition coefficient (shake-flask method) was tested to determine the lipophilicity of these compounds. In the next stage of testing EDChA and ETChA-(compounds characterized by the highest degree of free radical scavenging), the penetration of DPPH through pig skin and its accumulation in the skin were evaluated. For comparison, penetration studies of eugenol alone as well as dichloroacetic acid (DChAA) and trichloroacetic acid (TChAA) were also carried out. The antioxidant activity (DPPH, ABTS, and Folin-Ciocalteu methods) of the fluid that penetrated through pig skin was also evaluated. The in vitro pig skin penetration study showed that eugenol derivatives are particularly relevant for topical application. The obtained derivatives were characterized by a high level of antioxidant activity estimated after 24 h of conducting the experiment, which indicates long-term protection against reactive oxygen species (ROS) in the deeper layers of the skin.

Melanosome transport and regulation in development and disease

Melanosomes are specialized membrane-bound organelles that synthesize and organize melanin, ultimately providing color to the skin, hair, and eyes. Disorders in melanogenesis and melanosome transport are linked to pigmentary diseases, such as Hermansky-Pudlak syndrome, Chediak-Higashi syndrome, and Griscelli syndrome. Clinical cases of these pigmentary diseases shed light on the molecular mechanisms that control melanosome-related pathways. However, only an improved understanding of melanogenesis and melanosome transport will further the development of diagnostic and therapeutic approaches. Herein, we review the current literature surrounding melanosomes with particular emphasis on melanosome membrane transport and cytoskeleton-mediated melanosome transport. We also provide perspectives on melanosome regulatory mechanisms which include hormonal action, inflammation, autophagy, and organelle interactions.

Genetic Alterations in the INK4a/ARF Locus: Effects on Melanoma Development and Progression

Genetic alterations in the INK4a/ARF (or CDKN2A) locus have been reported in many cancer types, including melanoma; head and neck squamous cell carcinomas; lung, breast, and pancreatic cancers. In melanoma, loss of function CDKN2A alterations have been identified in approximately 50% of primary melanomas, in over 75% of metastatic melanomas, and in the germline of 40% of families with a predisposition to cutaneous melanoma. The CDKN2A locus encodes two critical tumor suppressor proteins, the cyclin-dependent kinase inhibitor p16^INK4a and the p53 regulator p14^ARF. The majority of CDKN2A alterations in melanoma selectively target p16^INK4a or affect the coding sequence of both p16^INK4a and p14^ARF. There is also a subset of less common somatic and germline INK4a/ARF alterations that affect p14^ARF, while not altering the syntenic p16^INK4a coding regions. In this review, we describe the frequency and types of somatic alterations affecting the CDKN2A locus in melanoma and germline CDKN2A alterations in familial melanoma, and their functional consequences in melanoma development. We discuss the clinical implications of CDKN2A inactivating alterations and their influence on treatment response and resistance.

Dedifferentiation of human epidermal melanocytes in vitro by long-term trypsinization

Human epidermal melanocytes can be induced to form melanocyte spheroids and revert to immature characteristics by long-term trypsinization (LTT). To further explore the biological characteristics of melanocytes after LTT and to study the underlying mechanism. Melanocytes were subjected to long-term (2 h) trypsinization in this study, after which their viability, proliferation and autophagy were characterized. The expression of melanocyte markers [human melanoma black45 (HMB45), tyrosinase (TYR) and Nestin] was detected and relative expression levels of mRNAs encoding TYR, Nestin, c-Kit and microphthalmia-associated transcription factor (MITF) were determined. After LTT, more short spindle-shaped melanocytes appeared and viability assays demonstrated that most melanocytes survived that treatment but had decreased proliferation rates compared to the untreated controls. There was a significant increase in autophagy of melanocytes after LTT and the expression of TYR was decreased compared with untreated control melanocytes. There were no significant differences in the expression of HMB45 or Nestin between the two groups. Compared with untreated melanocytes, levels of message ribonucleic acid (mRNAs) encoding TYR, c-Kit and MITF were decreased after LTT, while Nestin mRNA levels were increased. These results clarified that Long-term treatment with trypsin causes the dedifferentiation of mature epidermal melanocytes in vitro.

Skin colour and vitamin D: An update

Homo sapiens evolved in East Africa and had dark skin, hair, and eyes, in order to protect against deleterious consequences of intensive UV radiation at equatorial latitudes. Intensive skin pigmentation was thought to bear the risk of inefficient vitamin D3 synthesis in the skin. This initiated the hypothesis that within the past 75 000 years, in which humans migrated to higher latitudes in Asia and Europe, the need for vitamin D3 synthesis served as an evolutionary driver for skin lightening. In this review, we summarize the recent archeogenomic reconstruction of population admixture in Europe and demonstrate that skin lightening happened as late as 5000 years ago through immigration of lighter pigmented populations from western Anatolia and the Russian steppe but not primarily via evolutionary pressure for vitamin D3 synthesis. We show that variations in genes encoding for proteins being responsible for the transport, metabolism and signalling of vitamin D provide alternative mechanisms of adaptation to a life in northern latitudes without suffering from consequences of vitamin D deficiency. This includes hypotheses explaining differences in the vitamin D status and response index of European populations.

Chloroacridine derivatives as potential anticancer agents which may act as tricarboxylic acid cycle enzyme inhibitors

PURPOSE

This paper concerns the cytotoxicity of 9-chloro-1-nitroacridine (1a) and 9-chloro-4-methyl-1-nitroacridine (1b) against two biologically different melanoma forms: melanotic and amelanotic. Melanomas are tumors characterized by high heterogeneity and poor susceptibility to chemotherapies. Among new analogs synthesized by us, compound 1b exhibited the highest anticancer potency. Because of that, in this study, we analyzed the mechanism of action for 1a and its 4-methylated derivative, 1b, against a pair of biological melanoma forms, with regard to proliferation, cell death mechanism and energetic state.

METHODS

Cytotoxicity was evaluated by XTT assay. Cell death was estimated by plasma membrane structure changes (phosphatidylserine externalization), caspase activation, and ROS presence. The energetic state of cells was estimated based on NAD and ATP levels, and the activity of tricarboxylic acid cycle enzymes (pyruvate dehydrogenase complex, aconitase, isocitrate dehydrogenase).

RESULTS

The chloroacridines affect biological forms of melanoma in different ways. Amelanotic (Ab) melanoma (with inhibited melanogenesis and higher malignancy) was particularly sensitive to the action of the chloroacridines. The Ab melanoma cells died through apoptosis and through death without caspase activation. Diminished activity of TAC enzymes was noticed among Ab melanoma cells together with ATP/NAD depletion, especially in the case of 1b.

CONCLUSION

Our data show that the biological forms of the tumors responded to 1a and its 4-methylated analog in different ways. 1a and 1b could be inducers of regulated melanoma cell death, especially the amelanotic form. Although the mechanism of the cell death is not fully understood, 1b may act by interfering with the TAC enzymes and blocking specific pathways leading to tumor growth. This could encourage further investigation of its anticancer activity, especially against the amelanotic form of melanoma.

Insufficient Sun Exposure Has Become a Real Public Health Problem

This article aims to alert the medical community and public health authorities to accumulating evidence on health benefits from sun exposure, which suggests that insufficient sun exposure is a significant public health problem. Studies in the past decade indicate that insufficient sun exposure may be responsible for 340,000 deaths in the United States and 480,000 deaths in Europe per year, and an increased incidence of breast cancer, colorectal cancer, hypertension, cardiovascular disease, metabolic syndrome, multiple sclerosis, Alzheimer's disease, autism, asthma, type 1 diabetes and myopia. Vitamin D has long been considered the principal mediator of beneficial effects of sun exposure. However, oral vitamin D supplementation has not been convincingly shown to prevent the above conditions; thus, serum 25(OH)D as an indicator of vitamin D status may be a proxy for and not a mediator of beneficial effects of sun exposure. New candidate mechanisms include the release of nitric oxide from the skin and direct effects of ultraviolet radiation (UVR) on peripheral blood cells. Collectively, this evidence indicates it would be wise for people living outside the tropics to ensure they expose their skin sufficiently to the sun. To minimize the harms of excessive sun exposure, great care must be taken to avoid sunburn, and sun exposure during high ambient UVR seasons should be obtained incrementally at not more than 5-30 min a day (depending on skin type and UV index), in season-appropriate clothing and with eyes closed or protected by sunglasses that filter UVR.

Laminin-511-E8 promotes efficient in vitro expansion of human limbal melanocytes

Limbal melanocytes, located in the basal epithelial layer of the corneoscleral limbus, represent essential components of the corneal epithelial stem cell niche, but, due to difficulties in their isolation and cultivation, their biological roles and potential for stem cell-based tissue engineering approaches have not been comprehensively studied. Here, we established a protocol for the efficient isolation and cultivation of pure populations of human limbal melanocytes, which could be expanded at high yield by using recombinant laminin (LN)-511-E8 as culture substrate. Co-cultivation of limbal melanocytes with limbal epithelial stem/progenitor cells on fibrin hydrogels pre-incubated with LN-511-E8 resulted in multilayered stratified epithelial constructs within ten days. By reproducing physiological cell–cell and cell–matrix interactions of the native niche environment, these biomimetic co-culture systems provide a promising experimental model for investigating the functional roles of melanocytes in the limbal stem cell niche and their suitability for developing advanced epithelial grafts for ocular surface surface reconstruction.

Oncogenic BRAF, endoplasmic reticulum stress, and autophagy: Crosstalk and therapeutic targets in cutaneous melanoma

BRAF is a member of the RAF family of serine/threonine-specific protein kinases. Oncogenic BRAF, in particular, BRAF V600E, can disturb the normal protein folding machinery in the endoplasmic reticulum (ER) leading to accumulation of unfolded/misfolded proteins in the ER lumen, a condition known as endoplasmic reticulum (ER) stress. To alleviate such conditions, ER-stressed cells have developed a highly robust and adaptable signaling network known as unfolded protein response (UPR). UPR is ordinarily a cytoprotective response and usually operates through the induction of autophagy, an intracellular lysosomal degradation pathway that directs damaged proteins, protein aggregates, and damaged organelles for bulk degradation and recycling. Both ER stress and autophagy are involved in the progression and chemoresistance of melanoma. Melanoma, which arises as a result of malignant transformation of melanocytes, exhibits exceptionally high therapeutic resistance. Many mechanisms of therapeutic resistance have been identified in individual melanoma patients and in preclinical BRAF-driven melanoma models. Recently, it has been recognized that oncogenic BRAF interacts with GRP78 and removes its inhibitory influence on the three fundamental ER stress sensors of UPR, PERK, IRE1α, and ATF6. Dissociation of GRP78 from these ER stress sensors prompts UPR that subsequently activates cytoprotective autophagy. Thus, pharmacological inhibition of BRAF-induced ER stress-mediated autophagy can potentially resensitize BRAF mutant melanoma tumors to apoptosis. However, the underlying molecular mechanism of how oncogenic BRAF elevates the basal level of ER stress-mediated autophagy in melanoma tumors is not well characterized. A better understanding of the crosstalk between oncogenic BRAF, ER stress and autophagy may provide a rationale for improving existing cancer therapies and identify novel targets for therapeutic intervention of melanoma.

Therapeutic Potential of Patient iPSC-Derived iMelanocytes in Autologous Transplantation

Induced pluripotent stem cells (iPSCs) are a promising melanocyte source as they propagate indefinitely and can be established from patients. However, the in vivo functions of human iPSC-derived melanocytes (hiMels) remain unknown. Here, we generated hiMels from vitiligo patients using a three-dimensional system with enhanced differentiation efficiency, which showed characteristics of human epidermal melanocytes with high sequence similarity and involved in multiple vitiligo-associated signaling pathways. A modified hair follicle reconstitution assay in vivo showed that MITF⁺PAX3⁺TYRP1⁺ hiMels were localized in the mouse hair bulb and epidermis and produced melanin up to 7 weeks after transplantation, whereas MITF⁺PAX3⁺TYRP1^- hiMelanocyte stem cells integrated into the bulge-subbulge regions. Overall, these data demonstrate the long-term functions of hiMels in vivo to reconstitute pigmented hair follicles and to integrate into normal regions for both mature melanocytes and melanocyte stem cells, providing an alternative source of personalized cellular therapy for depigmentation.

Central nervous system ganglioneuroblastoma harboring MYO5A-NTRK3 fusion

Central nervous system (CNS) ganglioneuroblastoma is a rare neuroectodermal neoplasm and little is known about its clinical and biological features. Herein, we report a pediatric case of CNS ganglioneuroblastoma harboring MYO5A-NTRK3 fusion. The patient, a 4-year-old boy, underwent a partial resection of a supratentorial tumor that was histopathologically diagnosed as a CNS ganglioneuroblastoma. Treatment with radiotherapy was started per the St Jude Medulloblastoma 03 (SJMB03) protocol; however, the tumor progressed rapidly and radiotherapy was temporally discontinued. Meanwhile, the patient underwent a second surgery, in which a gross total resection was successfully performed, following which he completed the remaining protocol-based therapy. Although an early focal recurrence was detected for which he received additional radiotherapy and oral temozolomide, the patient remained in complete remission for 14 months after the completion of the treatment. A central pathological review and molecular analysis were performed that revealed a MYO5A-NTRK3 fusion. Interestingly, the MYO5A-NTRK3 fusion has been recurrently detected in melanocytic tumors but not in other types of tumors. Therefore, it can be speculated that our case might partly share tumorigenesis mechanisms with MYO5A-NTRK3-positive melanocytic tumors. In addition, our case may enable an improved understanding of the pathogenesis and clinical features of CNS ganglioneuroblastomas.

PD-L1 produced by HaCaT cells under polyinosinic-polycytidylic acid stimulation inhibits melanin production by B16F10 cells

Skin forms a physical barrier that protects the body against outside agents. The deepest layer of the skin, the stratum basale, contains two cell types: agent-sensing keratinocytes, and melanin-producing melanocytes. Keratinocytes can sense both harmless commensal organisms and harmful pathogens via Toll-like receptors (TLRs), and keratinocytes subsequently drive immune responses. Activation of TLR3 is required for barrier repair because it stimulates essential genes, including tight junction genes, and inflammatory cytokines. Within the basal layer of the skin, resident melanocytes use their dendritic processes to connect with approximately 30–40 neighboring keratinocytes. Most studies have focused on the transfer of melanin-synthesizing melanosomes from melanocytes to keratinocytes, but the potential regulation of melanogenesis by soluble factor(s) produced by keratinocytes remains to be explored. Studying such regulation in vivo is challenging because of the keratinocyte:melanocyte ratio in the epidermis and the location of the cells within the skin. Therefore, in this study, we investigated whether keratinocytes affected melanocyte melanogenesis in vitro under normal or inflammatory conditions. We found that polyinosinic-polycytidylic acid [poly(I:C)] stimulation induced PD-L1 secretion from HaCaT cells and that poly(I:C)-induced PD-L1 inhibited melanin production by B16F10 cells. These data provide key evidence that keratinocytes can alter melanocyte melanogenesis via the production of soluble factors under inflammatory conditions.

Deciphering skin re-pigmentation patterns in vitiligo: an update on the cellular and molecular events involved

Current treatment of vitiligo is still a great challenge, since most cases of vitiligo have variable re-pigmentation outcomes due to their unpredictable responses to existing therapeutic regimens. There is an urgent need to identify this re-pigmentation process and to develop novel therapies. This review illustrates the most current research and latest understanding of vitiligo skin re-pigmentation and related regulatory mechanisms. Literature was collected from PubMed until January 2020, using the search terms including "vitiligo," "re-pigmentation," "phototherapy," "narrow-band ultraviolet B, " "excimer," "fractional carbon dioxide laser," and "melanocyte stem cells." Literature was mainly derived from English articles. Article type was not limited. Emerging evidence suggests that patients with vitiligo present various re-pigmentation patterns following ultraviolet B phototherapy, which relies on different cell reservoirs from the perilesional margins and/or from uninvolved hair follicles to replenish functional melanocytes that are lost in vitiliginous skin. The following events are likely to be involved in this re-pigmentation process, including: 1) changes in the paracrine secretion and distribution of transforming growth factor-β1 in the bulge area and in the epidermis; 2) the enhanced transfer of dermal pro-melanogenic growth factors to the epidermis; and 3) the induction of a C-X-C motif chemokine ligand (CXCL) 12-enriched micro-environment that efficiently recruits CXCR4- or CXCR7-positive melanocytes. Ongoing studies on the cellular and molecular events underlying vitiligo re-pigmentation will help design new therapeutic strategies to improve treatment outcomes.

Childhood vitiligo in Egypt: Clinico-epidemiologic Profile of 483 patients

BACKGROUND

Childhood vitiligo is commonly encountered. Pattern and distribution of childhood vitiligo were not clearly described in past.

AIMS

To study clinical characteristics of vitiligo among Egyptian children in relation to epidemiological data and compare them with those of adolescents and adults.

PATIENTS AND METHODS

Recruited clinically diagnosed vitiligo patients were categorized into three groups: I (children): <12 years old (yo), II (adolescents): 12-18 yo, and III (adults): 18-30 yo. Patients were subjected to history taking, general and dermatological examination to determine skin phototype, type, presentation, and distribution of vitiligo, percentage of body area involved using vitiligo extent score (VES), associated mucosal involvement, presence of leukotrichia, koebnerization, and halo nevi.

RESULTS

A total of 483 vitiligo patients were included: 220 children, 123 adolescents, and 140 adults. The most common form of vitiligo was nonsegmental vitiligo (NSV). Segmental and active vitiligo were more common in children than in adolescents and adults. The most common site of distribution of NSV in children was the face (periocular) vs arms and forearms in adults followed by thighs and legs in both. The mean age of onset of vitiligo in children was 6.18 (SD 2.93) yo, while mean duration of disease was 2.12 (SD 2.21) y. Face was the most common site of onset of vitiligo in children and adolescents vs arms and forearms in adults.

CONCLUSIONS

Childhood vitiligo differs from adult onset vitiligo regarding several features as type, site of onset, distribution, extent, and activity of disease.

Non-Cytotoxic Sulfated Heterorhamnan from Gayralia brasiliensis Green Seaweed Reduces Driver Features of Melanoma Metastatic Progression

Melanoma is a form of skin cancer with high mortality owing to its fast progression and metastatic capacity. The treatments available nowadays are only palliative in advanced stages of the disease. Thus, alternative therapies for cancer treatment are in demand, and molecules from natural sources, such as polysaccharides, could represent new possible therapeutic approaches. Polysaccharides of freshwater and marine algae with biological activities, such as antitumor properties, are greatly reported in the scientific literature. In the present study, a sulfated heterorhamnan obtained from the green seaweed Gayralia brasiliensis (Gb1 fraction) was chemically characterized and its biological activities in the B16-F10 murine melanoma cell line were evaluated. The Gb1 polysaccharidic fraction tested concentrations presented low or absence of cytotoxicity to B16-F10 cells and neither cell proliferation nor cell cycle were altered. Interestingly, Gb1 treatment decreased B16-F10 cells migration and invasion capabilities and CD44 labeling, showing to be a promising compound for further in vitro and in vivo antitumor studies.

p-Hydroxybenzoic Acid β-d-Glucosyl Ester and Cimidahurinine with Antimelanogenesis and Antioxidant Effects from Pyracantha angustifolia via Bioactivity-Guided Fractionation

This study evaluated bioactivity-guided fractionation as a means to identify therapeutic phytochemicals from Pyracantha angustifolia that can attenuate melanogenesis and oxidation. Seven compounds with inhibitory effects on melanin production and tyrosinase (TYR) activity, and ABTS and DPPH radical-scavenging activities, which have not been reported as whitening materials, were isolated from the n-butanol fraction from P. angustifolia leaves (PAL). Among the seven compounds, p-hydroxybenzoic acid β-d-glucosylester (HG), and cimidahurinine (CH) had strong inhibitory effects on melanin production and TYR activity, as well as ABTS and DPPH radical-scavenging activities. Western blot analysis showed that HG and CH suppressed tyrosinase-related protein (TYRP)-1 and TYRP-2 expression. Moreover, HG and CH inhibited reactive oxygen species (ROS) generation in tert-butyl hydroperoxide (t-BHP)-treated B16F10 cells. These results suggest that P. angustifolia containing active compounds, such as HG and CH, is a potent therapeutic candidate for the development of hypopigmenting agents.

Particulate mediators of the bystander effect linked to suicide and interferon-β transgene expression in melanoma cells

In the context of comparative oncology, melanoma cells derived from companion animal tumors are good models for optimizing and predicting their in vivo response to therapeutic strategies. Here, we report that human, canine, and feline melanoma cells driven to death by bleomycin, interferon-β gene, or herpes simplex virus thymidine kinase/ganciclovir suicide gene (SG) treatment significantly increased their internal granularity. This fact correlated with the release of a heterogeneous collection of nano- and micro-sized granules as revealed by transmission electron microscopy. While killing lipofected cells, the expressed transgenes and their derived products were incorporated into these granules that were isolated by differential centrifugation. These particulate factors (PFs) were able to transfer, in a dose- and time-dependent manner, appreciable levels of therapeutic genes, related proteins, and drugs. Thus, when recipient cells of SG-carrying PFs were exposed to ganciclovir, this prodrug was efficiently activated, eliminating them. These PFs kept the functionality of their cargo, even after being subjected to adverse conditions, such as the presence of DNase, freezing, or heating. Since our in vitro system did not include any of the immune mechanisms that could provide additional antitumor activity, the chemo-gene treatments amplified by these delivery bags of therapeutic agents offer a great clinical potential.

The Role of Memory CD8+ T Cells in Vitiligo

Vitiligo is an autoimmune skin disease mediated by autoreactive CD8⁺ T cells that destroy the pigment-producing cells of the epidermis, melanocytes, leading to areas of depigmentation. Patients with vitiligo require lifelong treatment to regain and maintain their pigment. Clinical observations uncovered the importance of autoimmune memory in vitiligo because cessation of treatment frequently led to relapse of disease at the site of previous lesions. A subset of memory T cells known as CD8⁺ resident memory T cells (T_RM) are long-lived, nonmigratory memory cells that persist in most nonlymphoid tissues, including the skin. Recent reports describe the presence of CD8⁺ T_RM in lesional vitiligo patient skin and suggest their role as active players in disease maintenance. In this review, we will discuss the role of skin CD8⁺ T_RM in maintaining disease in vitiligo and the opportunity to target this population to induce a long-lasting reversal of disease.

Deconvoluting Wavelengths Leading to Fluorescent Light Induced Inflammation and Cellular Stress in Zebrafish (Danio rerio)

Fluorescent light (FL) has been shown to induce a cellular immune and inflammatory response that is conserved over 450 MY of evolutionary divergence and among vertebrates having drastically different lifestyles such as Mus musculus, Danio rerio, Oryzias latipes and Xiphophorus maculatus. This surprising finding of an inflammation and immune response to FL not only holds for direct light receiving organs (skin) but is also observed within internal organs (brain and liver). Light responsive genetic circuitry initiated by the IL1B regulator induces a highly conserved acute phase response in each organ assessed for all of biological models surveyed to date; however, the specific light wavelengths triggering this response have yet to be determined so investigation of mechanisms and/or light specific molecule(s) leading to this response are difficult to assess. To understand how specific light wavelengths are received in both external and internal organs, zebrafish were exposed to specific 50 nm light wavebands spanning the visible spectrum from 300–600 nm and the genetic responses to each waveband exposure were assessed. Surprisingly, the induced cellular stress response previously observed following FL exposure is not triggered by the lower “damaging” wavelengths of light (UVB and UVA from 300–400 nm) but instead is maximally induced by higher wavelengths ranging from 450–500 nm in skin to 500–600 nm in both brain and liver).

Misregulation of ELK1, AP1, and E12 Transcription Factor Networks Is Associated with Melanoma Progression

Melanoma is among the most malignant cutaneous cancers and when metastasized results in dramatically high mortality. Despite advances in high-throughput gene expression profiling in cancer transcriptomic studies, our understanding of mechanisms driving melanoma progression is still limited. We present here an in-depth bioinformatic analysis of the melanoma RNAseq, chromatin immunoprecipitation (ChIP)seq, and single-cell (sc)RNA seq data to understand cancer progression. Specifically, we have performed a consensus network analysis of RNA-seq data from clinically re-grouped melanoma samples to identify gene co-expression networks that are conserved in early (stage 1) and late (stage 4/invasive) stage melanoma. Overlaying the fold-change information on co-expression networks revealed several coordinately up or down-regulated subnetworks that may play a critical role in melanoma progression. Furthermore, by incorporating histone lysine-27 acetylation information and highly expressed genes identified from the single-cell RNA data from melanoma patient samples, we present a comprehensive list of pathways, putative protein-protein interactions (PPIs) and transcription factor (TF) networks that are driving cancer progression. From this analysis, we have identified Elk1, AP1 and E12 TF networks that coordinately change expression in late melanoma when compared to early melanoma, implicating these TFs in melanoma progression. Additionally, the sumoylation-associated interactome is upregulated in invasive melanoma. Together, this bioinformatic analysis potentially implicates a combination of TF networks and PPIs in melanoma progression, which if confirmed in the experimental systems, could be used as targets for drug intervention in melanoma.

The impact of NBUVB on microbial community profiling in the lesional skin of vitiligo subjects

BACKGROUND

The impact of NBUVB on the cutaneous microbiota of vitiligo patients remains to be fully elucidated.

METHODS

To characterize the cutaneous microbiota in vitiligo patients, cutaneous samples from 60 patients with vitiligo and after NBUVB irradiation were profiled using the Illumina MiSeq platform. Alpha diversity estimations revealed higher microbiota diversity in samples from patients with lesional skin. Beta diversity (Principal Component Analysis (PCA)) analysis showed that the bacterial community structure segregated differently between different groups.

RESULTS

There was a statistically significant increase in the Sobs, ACE, and Chao indices in the NB group compared with NF group, as determined by t-test. The alpha diversity have no significant difference between NF and DB group. At the phylum level, Firmicutes, Proteobacteria and Actinobacteria were the most predominant phyla. Propionibacterium and Pseudomonas were the most predominant genera in each group. In addition, Staphylococcus, Bacillus and Prevotella were enriched in DF group compared to DB group. Propionibacterium was enriched in DB group compared to DF group.

CONCLUSIONS

Our studies indicate differences in microbial community dynamics of the lesional and non-lesional sites of vitiligo subjects, with greater diversity and higher association between microbial communities of the unaffected site. And NBUVB irradiation might eliminate these differences.

Melochia corchorifolia extract inhibits melanogenesis in B16F10 mouse melanoma cells via activation of the ERK signaling

BACKGROUND

Numerous researches have focused on discovering available inhibitors of melanogenesis from natural medicinal plants with stable efficacy and safety to resolve cutaneous hyperpigmentary problems. Melochia corchorifolia Linn. (MC) has been used as folk medicine to treat various diseases. However, the effect of MC on melanogenesis remains unknown.

AIM

In this study, we investigated the effect of MC extract on melanogenesis and its underlying mechanisms in B16F10 mouse melanoma cells.

METHODS

B16F10 cells were treated with MC extract, and then, cell viability, melanin content, and tyrosinase activity were analyzed. The mRNA and protein expression of tyrosinase and microphthalmia-associated transcription factor (MITF) were evaluated using real-time quantitative polymerase chain reaction (RT-qPCR) and Western blotting, respectively. Phosphorylated or total protein levels in MC extract-induced signaling pathways were analyzed by Western blotting.

RESULTS

Treatment of B16F10 cells with MC extract inhibited melanin synthesis and intracellular tyrosinase activity in a dose-dependent manner with no cytotoxicity. Protein and mRNA expressions of tyrosinase and MITF were also significantly decreased by MC extract treatment. In addition, phosphorylated level of extracellular signal-regulated kinase (ERK) was obviously increased by MC extract, but AKT pathway was not activated. Inhibited ERK phosphorylation by pretreatment with a selective ERK inhibitor PD98059 significantly reversed the decreased melanin content induced by treatment with MC extract in B16F10 cells.

CONCLUSION

MC extract inhibits melanogenesis in B16F10 mouse melanoma cells through suppression of MITF-tyrosinase signaling pathway by ERK activation.

Dissimilar Appearances Are Deceptive-Common microRNAs and Therapeutic Strategies in Liver Cancer and Melanoma

: In this review, we summarize the current knowledge on miRNAs as therapeutic targets in two cancer types that were frequently described to be driven by miRNAs-melanoma and hepatocellular carcinoma (HCC). By focusing on common microRNAs and associated pathways in these-at first sight-dissimilar cancer types, we aim at revealing similar molecular mechanisms that are evolved in microRNA-biology to drive cancer progression. Thereby, we also want to outlay potential novel therapeutic strategies. After providing a brief introduction to general miRNA biology and basic information about HCC and melanoma, this review depicts prominent examples of potent oncomiRs and tumor-suppressor miRNAs, which have been proven to drive diverse cancer types including melanoma and HCC. To develop and apply miRNA-based therapeutics for cancer treatment in the future, it is essential to understand how miRNA dysregulation evolves during malignant transformation. Therefore, we highlight important aspects such as genetic alterations, miRNA editing and transcriptional regulation based on concrete examples. Furthermore, we expand our illustration by focusing on miRNA-associated proteins as well as other regulators of miRNAs which could also provide therapeutic targets. Finally, design and delivery strategies of miRNA-associated therapeutic agents as well as potential drawbacks are discussed to address the question of how miRNAs might contribute to cancer therapy in the future.

Premature cell senescence in human skin: Dual face in chronic acquired pigmentary disorders

Although senescence was originally described as an in vitro acquired cellular characteristic, it was recently recognized that senescence is physiologically and pathologically involved in aging and age-related diseases in vivo. The definition of cellular senescence has expanded to include the growth arrest caused by various cellular stresses, including DNA damage, inadequate mitochondria function, activated oncogene or tumor suppressor genes and oxidative stress. While senescence in normal aging involves various tissues over time and contributes to a decline in tissue function even with healthy aging, disease-induced premature senescence may be restricted to one or a few organs triggering a prolonged and more intense rate of accumulation of senescent cells than in normal aging. Organ-specific high senescence rate could lead to chronic diseases, especially in post-mitotic rich tissue. Recently, two opposite acquired pathological conditions related to skin pigmentation were described to be associated with premature senescence: vitiligo and melasma. In both cases, it was demonstrated that pathological dysfunctions are not restricted to melanocytes, the cell type responsible for melanin production and transport to surrounding keratinocytes. Similar to physiological melanogenesis, dermal and epidermal cells contribute directly and indirectly to deregulate skin pigmentation as a result of complex intercellular communication. Thus, despite senescence usually being reported as a uniform phenotype sharing the expression of characteristic markers, skin senescence involving mainly the dermal compartment and its paracrine function could be associated with the disappearance of melanocytes in vitiligo lesions and with the exacerbated activity of melanocytes in the hyperpigmentation spots of melasma. This suggests that the difference may arise in melanocyte intrinsic differences and/or in highly defined microenvironment peculiarities poorly explored at the current state of the art. A similar dualistic phenotype has been attributed to intratumoral stromal cells as cancer-associated fibroblasts presenting a senescent-like phenotype which influence the behavior of neoplastic cells in either a tumor-promoting or tumor-inhibiting manner. Here, we present a framework dissecting senescent-related molecular alterations shared by vitiligo and melasma patients and we also discuss disease-specific differences representing new challenges for treatment.

The accuracy of elastographic strain ratio and ultrasound thickness in the differentiation of thin and thick cutaneous melanoma

Background

Cutaneous melanoma is the most deadly of skin neoplasms. Few studies have investigated the role of elastography characteristics so the ability of elastography in the differentiation of thin and thick cutaneous melanoma is still narrow.

Purpose

To investigate the accuracy of elastography in differentiating thin and thick melanoma, by measuring strain ratio (SR) between the lesion and adjacent dermis and hypodermis.

Material and Methods

We investigated by ultrasound and elastography 52 melanoma lesions in 49 patients. The receiver operating characteristic (ROC) curve method was used to investigate the accuracy of ultrasound and elastographic measurement of SR to surrounding tissue, in the differentiation of thin and thick melanomas. The histopathological measurement of lesions depth called Breslow index was the golden standard test.

Results

Areas under the curve (AUC) showed low accuracy for SR to hypodermis in distinguishing between thin melanomas and others (AUC = 0.739, 95% confidence interval [CI] = 0.508–0.970]) with a cut-off value of 0.950, being the only statistically significant result in matter of elastographic measurements. Highly statistically significant results were obtained for B-mode ultrasound depth measurements of the lesion, with an AUC = 0.970 (95% CI = 0.927–1.0) in discriminating thin melanomas of others and 0.951 (95% CI = 0.869–1.0) in discriminating thick melanomas of other types.

Conclusion

Despite the appearance that SR may correlate with the depth of the lesion, elastography, by measuring the SRs to dermis and hypodermis, does not have enough accuracy in distinguishing thin and thick melanoma.

Melanoma Metabolism: Cell Survival and Resistance to Therapy

Cutaneous melanoma is one of the most aggressive types of cancer, presenting the highest potential to form metastases, both locally and distally, which are associated with high death rates of melanoma patients. A high somatic mutation burden is characteristic of these tumours, with most common oncogenic mutations occurring in the BRAF, NRAS and NF1 genes. These intrinsic oncogenic pathways contribute to the metabolic switch between glycolysis and oxidative phosphorylation metabolisms of melanoma, facilitating tumour progression and resulting in a high plasticity and adaptability to unfavourable conditions. Moreover, melanoma microenvironment can influence its own metabolism and reprogram several immune cell subset functions, enabling melanoma to evade the immune system. The knowledge of the biology, molecular alterations and microenvironment of melanoma has led to the development of new targeted therapies and the improvement of patient care. In this work, we reviewed the impact of melanoma metabolism in the resistance to BRAF and MEK inhibitors and immunotherapies, emphasizing the requirement to evaluate metabolic alterations upon development of novel therapeutic approaches. Here we summarized the current understanding of the impact of metabolic processes in melanomagenesis, metastasis and microenvironment, as well as the involvement of metabolic pathways in the immune modulation and resistance to targeted and immunocheckpoint therapies.

Transcriptional Differences of Coding and Non-Coding Genes Related to the Absence of Melanocyte in Skins of Bama Pig

Skin is the body’s largest organ, and the main function of skin is to protect underlying organs from possible external damage. Melanocytes play an important role in skin pigmentation. The Bama pig has a “two-end-black” phenotype with different coat colors across skin regions, e.g., white skin (without melanocytes) and black skin (with melanocytes), which could be a model to investigate skin-related disorders, specifically loss of melanocytes. Here, we generated expression profiles of mRNAs and long noncoding RNAs in Bama pig skins with different coat colors. In total, 14,900 mRNAs and 7549 lncRNAs were expressed. Overall, 2338 mRNAs/113 lncRNAs with FDR-adjusted p-value ≤ 0.05 were considered to be differentially expressed (DE) mRNAs/lncRNAs, with 1305 down-regulated mRNAs and 1033 up-regulated mRNAs in white skin with|log₂(fold change)| > 1. The genes down-regulated in white skin were associated with pigmentation, melanocyte–keratinocyte interaction, and keratin, while up-regulated ones were mainly associated with cellular energy metabolisms. Furthermore, those DE lncRNAs were predicted to be implicated in pigmentation, keratin synthesis and cellular energy metabolism. In general, this study provides insight into the transcriptional difference involved in melanocyte-loss-induced keratinocyte changes and promotes the Bama pig as a biomedical model in skin research.

Thymosin β4 Regulates Focal Adhesion Formation in Human Melanoma Cells and Affects Their Migration and Invasion

Thymosin β4 (Tβ4), a multifunctional 44-amino acid polypeptide and a member of actin-binding proteins (ABPs), plays an important role in developmental processes and wound healing. In recent years an increasing number of data has been published suggesting Tβ4's involvement in tumorigenesis. However, Tβ4's role in melanoma tumor development still remains to be elucidated. In our study we demonstrate that Tβ4 is crucial for melanoma adhesion and invasion. For the purpose of our research we tested melanoma cell lines differing in invasive potential. Moreover, we applied shRNAs to silence TMSB4X (gene encoding Tβ4) expression in a cell line with high TMSB4X expression. We found out that Tβ4 is not only a component of focal adhesions (FAs) and interacts with several FAs components but also regulates FAs formation. We demonstrate that Tβ4 level has an impact on FAs' number and morphology. Moreover, manipulation with TMSB4X expression resulted in changes in cells' motility on non-coated and Matrigel^TM (resembling basement membrane composition)-coated surfaces and drastically decreased invasion abilities of the cells. Additionally, a correlation between Tβ4 expression level and exhibition of mesenchymal-like [epithelial-mesenchymal transition (EMT)] features was discovered. Cells with lowered TMSB4X expression were less EMT-progressed than control cells. Summarizing, obtained results show that Tβ4 by regulating melanoma cells' adhesion has an impact on motility features and EMT. Our study not only contributes to a better understanding of the processes underlying melanoma cells' capacity to create metastases but also highlights Tβ4 as a potential target for melanoma management therapy.

A Review of Key Biological and Molecular Events Underpinning Transformation of Melanocytes to Primary and Metastatic Melanoma

Melanoma is a major public health concern that is responsible for significant morbidity and mortality, particularly in countries such as New Zealand and Australia where it is the commonest cause of cancer death in young adults. Until recently, there were no effective drug therapies for patients with advanced melanoma however significant advances in our understanding of the biological and molecular basis of melanoma in recent decades have led to the development of revolutionary treatments, including targeted molecular therapy and immunotherapy. This review summarizes our current understanding of the key events in the pathway of melanomagenesis and discusses the role of genomic analysis as a potential tool for improved diagnostic evaluation, prognostication and treatment strategies. Ultimately, it is hoped that a continued deeper understanding of the mechanisms of melanomagenesis will lead to the development of even more effective treatments that continue to provide better outcomes for patients with melanoma.

Literature review of Notch melanoma receptors

Despite the immunotherapeutics and target therapy agents, the survival of patients with advanced melanoma is still low. Notch signaling is able to regulate many aspects of melanomagenesis. Comparative analyses of common melanocytic nevi, dysplastic nevi and melanomas demonstrated increased expression of Notch1, Notch2 and their ligands, indicating that a positive regulation of these components may be related to the progression of melanoma. Some strategies such as gamma-secretase inhibitors (GSI) have been explored in patients with refractory metastatic disease or locally advanced disease of solid tumors. Two major classes of Notch inhibitors are currently in clinical development: GSI and monoclonal antibodies against Notch receptors or their ligands. Inhibition of Notch by GSI has been shown to decrease melanoma growth. GSI RO4929097 co-administered with cisplatin, vinblastine and temozolomide promotes greater elimination of tumor cells. The Notch pathway needs to be explored in the treatment of melanoma.

Enlarging melanocytic lesions with peripheral globular pattern: a dermoscopic and confocal microscopy study

BACKGROUND

Enlarging melanocytic lesions with peripheral globular pattern (EMLPGP) are a pitfall in dermoscopy. Our aim was to evaluate the meaning of EMLPGP and to assess the use of dermoscopy and reflectance confocal microscopy (RCM) in order to improve the clinical management of this subtype of melanocytic lesions.

METHODS

A total of 135 EMLPGP were recruited and, accordingly to the dermoscopy features, were removed; later, an expert dermoscopist reviewed the lesions blinded to histology. Moreover, a subgroup of 63 lesions who underwent also to RCM, were reviewed by an expert confocalist.

RESULTS

Patients had a median age of 41 years old and a female prevalence (61.5%). The main anatomic site was the trunk (86%). Histology of the 135 excised EMLPGP disclosed 116 nevi (86%; P<0.0001) and 19 melanomas (14%). On dermoscopy, statistical significance was detected for small globules that were observed in 106 cases (78.5%; P<0.0001), while globules distribution and color did not impact the diagnosis prediction, as well as age, sex or any other patient profile. Considering the RCM, atypical cytology and irregular architecture were detected in 100% of melanomas (P<0.0001).

CONCLUSIONS

Our study shows that EMLPGPs are detectable in every age and can be a pitfall in especially in high risk patients with an over-excision of lesions. The presence of peripheral globules should be evaluated considering the overall dermoscopic features. RCM can contribute significantly in the management of lesions trough the detection of cyto-architectural atypia. Therefore, RCM in combination with dermoscopy can optimize the reduction of harmless lesions.