Search Results (25)

Melanoma is a malignant tumor that originates in pigment-producing cells called melanocytes. This type of cancer remains a major public health challenge due to its high metastatic potential and resistance to treatment. Autophagy is a catabolic process that enables the controlled degradation of damaged cellular organelles and unnecessary or abnormal macromolecules. Its primary function is to maintain intracellular homeostasis and cell survival. There are three main types of autophagy: macroautophagy, microautophagy and chaperone-mediated autophagy (CMA). The role of autophagy in oncogenesis is multifaceted and context-dependent—depending on the type of cancer and its stage of development. Autophagy can either promote tumor progression or act as a tumor-suppressive mechanism. Factors influencing the role of autophagy in cancer include inflammation, crosstalk with apoptosis and resistance to anticancer therapies. Current research is focused on the use of both autophagy inhibitors and autophagy inducers as potential strategies to improve the effectiveness of melanoma treatment. Full article

Ultraviolet A (UVA) radiation disrupts the redox balance of melanocytes and may lead to the development of melanoma, highlighting the need for new skin protection strategies. This study assessed the effect of phytocannabinoids [cannabigerol (CBG), cannabidiol (CBD), and CBG + CBD] on redox homeostasis in control and UVA-exposed melanocytes and in melanoma cells (SK-Mel-5). UVA radiation increased the activity of prooxidant enzymes in both melanocytes and SK-Mel-5 cells and, consequently, the level of reactive oxygen species (ROS) (approx. 2-fold). It also activated nuclear factor erythroid 2 (Nrf2), as reflected by increased expression of heme oxygenase 1 (HO-1) (melanocytes approx. 2-fold; SK-Mel-5 approx. 7-fold). Concomitantly, antioxidant mechanisms were impaired, as demonstrated by reduced superoxide dismutase (SOD1/SOD2) activity and impaired glutathione and thioredoxin function. These changes were accompanied by increased levels of oxidative damage markers (isoprostanes, 4-hydroxynonenal-4-HNE, and 4-HNE-protein adducts) (43–100%) and increased inflammatory signaling, including increased expression of nuclear factor kappa B (NF-κB) subunits (melanocytes: p52 ~2-fold, p65 ~75%; SK-Mel-5: ~4–4.5-fold) and tumor necrosis factor alpha (TNF-α; ~30%). Phytocannabinoid treatment modulated these UVA-induced changes. In SK-Mel-5 cells, phytocannabinoids normalized the activity of prooxidant enzymes and consequently reduced ROS levels (~30%). They also reduced Nrf2 activation and HO-1 expression; however, CBG increased HO-1 level in melanocytes (~25–40%). Furthermore, phytocannabinoids enhanced antioxidant defense by increasing SOD activity, particularly in melanocytes (~10–40%), and restoring the glutathione and thioredoxin systems. Markers of oxidative damage were reduced by approximately 23–37% after treatment. Furthermore, phytocannabinoids attenuated NF-κB activation (p52 ~18–28%, p65 ~25–29% in melanocytes; ~20% in SK-Mel-5), while TNF-α levels remained unchanged. The effects in non-irradiated cells were modest (<15%). These results suggest that phytocannabinoid-mediated modulation of redox balance may stabilize melanocytes exposed to UVA radiation and potentially reduce the risk of neoplastic transformation. However, the observed protective effects in SK-Mel-5 cells require further investigation and detailed molecular analysis. Full article

Background: Chromosome 3p (chr3p) is frequently deleted in multiple cancers, indicating the presence of shared tumor suppressors. In aggressive uveal melanomas (UVM), this deletion often co-occurs with chr8q amplification (8q+), suggesting strong selection pressure during UVM evolution. Methods: To understand the pattern of genomic alterations mediated by chr3p deletion, we have developed an algorithm for detecting isochromosomes in 10,632 TCGA cancer patients. We further perform integrative genomics analysis to investigate how chr3p deletion could affect subsequent cancer genome evolution and synthetic lethality in UVM. Results: Analysis of genomic alterations in 33 different cancer types implicates the deletion or deleterious mutations of SET-domain-containing 2 (SETD2) at chr3p21 in significantly facilitating the formation of isochromosomes, thereby promoting genomic instability conducive to rapid cancer genome evolution. Fracturing of dicentric isochromosomes during cell division is pervasive and follows the dynamic fragmentation pattern of solids under impulse. In the most aggressive UVM subtype, chr3 deletion includes MITF, a master regulator of melanocyte survival and differentiation, and co-occurs with 8q+. We demonstrate that MITF is a master transcriptional regulator of GNAQ/GNA11 and associated synthetic-lethal genes in UVM. MITF maintains MAPK and calcium homeostasis in UVM, and its hemizygous deletion is thus accidental, likely creating an early crisis during oncogenesis. We further show that MITF, MYC, and GNAQ/GNA11 form coupled regulatory feedback loops in the melanocyte lineage, and MITF deletion in UVM creates acute dependency on MYC-mediated rescue via 8q+. The discovered feedback loops predict both overall and relapse-free patient survival within the most aggressive UVM subtype, explain sensitivity to therapeutic gene perturbations, and inform effective combinatorial therapies. Conclusions: SETD2 deletion potentiates isochromosome formation across diverse cancers. Combinatorial targeting of MITF together with a previously identified synthetic lethal gene may benefit UVM patients harboring both chr3 deletion and 8q+. Full article

Skin pigmentation results from the melanin production by melanocytes, an essential process for protection against ultraviolet radiation and for maintaining cutaneous homeostasis. Disruptions in this balance lead to pigmentary disorders, such as hyperpigmentation, which is characterized by localized or diffuse darkening of the skin. Its most prevalent forms include melasma, post-inflammatory hyperpigmentation, and solar lentigines, often driven by hormonal, inflammatory, and environmental factors, particularly sun exposure. Despite being clinically benign, these conditions have a significant impact on self-esteem and quality of life. Conventional treatments rely on depigmenting agents such as hydroquinone, retinoids, and corticosteroids, as well as chemical peels, and laser or light-based therapies, frequently used in combination. However, limited efficacy, prolonged treatment durations, and potential adverse effects underscore the need for safer and more effective alternatives. In recent years, research has focused on developing novel approaches, with nanotechnology-based delivery systems and minimally invasive techniques, such as microneedling, standing out as particularly promising fields. In parallel, the growing number of interventional clinical trials reflects an increasing interest in optimizing topical depigmenting strategies. This review summarizes the main types of hyperpigmentation, the depigmenting substances currently used, and emerging therapeutic approaches with potential clinical impact. Full article

Cutaneous malignant melanoma remains one of the most aggressive forms of skin cancer, characterized by high metastatic potential and resistance to standard therapies. Emerging evidence suggests that transient receptor potential (TRP) channels, non-selective cation channels involved in calcium homeostasis, and cellular stress responses play a pivotal role in melanoma development and progression. This review highlights the physiological expression of key TRP subfamilies (TRPM1, TRPM7, TRPM8, TRPV1, TRPV4, and TRPM2) in melanocytes and discusses their dysregulation in melanoma cells. TRPM1 is implicated as a tumor suppressor, whereas TRPM7, TRPV1, and TRPV4 often function as both melanoma suppressor or oncogenic drivers, modulating proliferation, apoptosis, and metastasis. TRPM2, which is responsive to oxidative stress, supports melanoma cell survival under metabolic stress. The potential of TRP channels as diagnostic biomarkers and therapeutic targets is evaluated, with attention paid to current pharmacological approaches and research challenges. The complexity and context-dependency of TRP function in melanoma underscore the need for isoform-specific modulation and personalized therapeutic strategies. Full article

Autoimmune CD8⁺ T cell-driven melanocyte destruction constitutes a key pathogenic mechanism in the development of vitiligo. Therefore, the pharmacological inhibition of CD8⁺ T cell effector functions and skin trafficking is a clinically viable therapeutic strategy. This study investigates leflunomide (LEF), an immunomodulatory drug with established safety in autoimmune diseases, for its therapeutic potential in a tyrosine-related protein (TRP) 2-180-induced vitiligo mouse model. Through flow cytometry, immunofluorescence, ELISA, and histopathological analyses, we systematically evaluated LEF’s effects on T cell regulation, chemokine expression, and cytokine profiles. Key findings demonstrated that LEF (20 mg/kg/day) significantly attenuated depigmentation by reducing CD8⁺ T cell infiltration and suppressing the IFN-γ-driven expression of CXCL9/10. Furthermore, LEF restored CD4⁺/CD8⁺ T cell homeostasis and rebalanced pro-inflammatory (IFN-γ, TNF-α, IL-2) and anti-inflammatory (IL-4, IL-10) cytokines, inducing a shift from Th1 to Th2. These results position LEF as an effective immunomodulator that disrupts the IFN-γ-CXCL9/10 axis and re-establishes immune balance, offering a promising repurposing strategy for halting vitiligo progression. Full article

Lysine, butyric acid, and zinc play important roles in skin homeostasis, which involves aging, inflammation, and prevention of skin barrier disruption. This bioactivity spectrum is not replicated by any one topical compound currently in use. Our purpose in this study was to characterize a novel compound, zinc dibutyroyllysinate (ZDL), consisting of zinc with lysine and butyric acid moieties. We used RNA-seq to evaluate its effect on gene expression in a full-thickness skin model. We show that lysine alone has minimal effects on gene expression, whereas ZDL had greater transcriptional bioactivity. The effects of ZDL included an increased expression of genes promoting epidermal differentiation and retinol metabolism, along with a decreased expression of microphthalmia-associated transcription factor (MITF) and other melanogenesis genes. These effects were not replicated by an alternative salt compound (i.e., calcium dibutyroyllysinate). ZDL additionally led to a dose-dependent increase in skin fibroblast extracellular matrix proteins, including collagen I, collagen IV, and prolidase. Loss of melanin secretion was also seen in ZDL-treated melanocytes. These results provide an initial characterization of ZDL as a novel topical agent. Our findings support a rationale for the development of ZDL as a skincare ingredient, with potential applications for diverse conditions, involving melanocyte hyperactivity, pigmentation, inflammation, or aging. Full article

Keratinocytes are major cellular components of the skin and are strongly involved in its homeostasis. Oncogenic events, starting mainly from excessive sun exposure, lead to the dysregulation of their proliferation and differentiation programs and promote the initiation and progression of non-melanoma skin cancers (NMSCs). Primary melanomas, which originate from melanocytes, initiate and develop in close interaction with keratinocytes, whose role in melanoma initiation, progression, and immune escape is currently being explored. Recent studies highlighted, in particular, unexpected modes of communication between melanocytic cells and keratinocytes, which may be of interest as sources of new biomarkers in melanomagenesis or potential therapeutic targets. This review aims at reporting the various contributions of keratinocytes in skin basal cell carcinoma (BCC), cutaneous squamous cell carcinoma (cSCC), and melanoma, with a greater focus on the latter in order to highlight some recent breakthrough findings. The readers are referred to recent reviews when contextual information is needed. Full article

Post-burn hypertrophic scars often exhibit abnormal pigmentation. Exosomes play important roles in maintaining normal physiological homeostasis and in the pathological development of diseases. This study investigated the effects of the exosomes derived from hypertrophic scar fibroblasts (HTSFs) on melanocytes, which are pigment-producing cells. Normal fibroblasts (NFs) and HTSFs were isolated and cultured from normal skin and hypertrophic scar (HTS) tissue. Both the NF- and HTSF-exosomes were isolated from a cell culture medium and purified using a column-based technique. The normal human epidermal melanocytes were treated with both exosomes at a concentration of 100 μg/mL at different times. The cell proliferation, melanin content in the medium, apoptotic factors, transcription factors, melanin synthesis enzymes, signaling, signal transduction pathways, and activators of transcription factors (STAT) 1, 3, 5, and 6 were investigated. Compared with the Dulbecco’s phosphate-buffered saline (DPBS)-treated controls and NF-exosomes, the HTSF-exosomes decreased the melanocyte proliferation and melanin secretion. The molecular patterns of apoptosis, proliferation, melanin synthesis, Smad and non-Smad signaling, and STATs were altered by the treatment with the HTSF-exosomes. No significant differences were observed between the DPBS-treated control and NF-exosome-treated cells. HTSF-derived exosomes may play a role in the pathological epidermal hypopigmentation observed in patients with HTS. Full article

Limbal epithelial progenitor cells (LEPC) rely on their niche environment for proper functionality and self-renewal. While extracellular vesicles (EV), specifically small EVs (sEV), have been proposed to support LEPC homeostasis, data on sEV derived from limbal niche cells like limbal mesenchymal stromal cells (LMSC) remain limited, and there are no studies on sEVs from limbal melanocytes (LM). In this study, we isolated sEV from conditioned media of LMSC and LM using a combination of tangential flow filtration and size exclusion chromatography and characterized them by nanoparticle tracking analysis, transmission electron microscopy, Western blot, multiplex bead arrays, and quantitative mass spectrometry. The internalization of sEV by LEPC was studied using flow cytometry and confocal microscopy. The isolated sEVs exhibited typical EV characteristics, including cell-specific markers such as CD90 for LMSC-sEV and Melan-A for LM-sEV. Bioinformatics analysis of the proteomic data suggested a significant role of sEVs in extracellular matrix deposition, with LMSC-derived sEV containing proteins involved in collagen remodeling and cell matrix adhesion, whereas LM-sEV proteins were implicated in other cellular bioprocesses such as cellular pigmentation and development. Moreover, fluorescently labeled LMSC-sEV and LM-sEV were taken up by LEPC and localized to their perinuclear compartment. These findings provide valuable insights into the complex role of sEV from niche cells in regulating the human limbal stem cell niche. Full article

Alpha-melanocyte-stimulating hormone (α-MSH) and its binding receptors (the melanocortin receptors) play important roles in maintaining ocular tissue integrity and immune homeostasis. Particularly extensive studies have demonstrated the biological functions of α-MSH in both immunoregulation and cyto-protection. This review summarizes the current knowledge of both the physiological and pathological roles of α-MSH and its receptors in the eye. We focus on recent developments in the biology of α-MSH and the relevant clinical implications in treating ocular diseases. Full article

Hypertension is known to be a multifactorial disease associated with abnormalities in neuroendocrine, metabolic, and hemodynamic systems. Poorly controlled hypertension causes more than one in eight premature deaths worldwide. Hydrochlorothiazide (HCT) and furosemide (FUR), being first-line drugs in the treatment of hypertension, are among others the most frequently prescribed drugs in the world. Currently, many pharmacoepidemiological data associate the use of these diuretics with an increased risk of adverse phototoxic reactions that may induce the development of melanoma and non-melanoma skin cancers. In this study, the cytotoxic and phototoxic potential of HCT and FUR against skin cells varied by melanin pigment content was assessed for the first time. The results showed that both drugs reduced the number of metabolically active normal skin cells in a dose-dependent manner. UVA irradiation significantly increased the cytotoxicity of HCT towards fibroblasts by approximately 40% and melanocytes by almost 20% compared to unirradiated cells. In the case of skin cells exposed to FUR and UVA radiation, an increase in cytotoxicity by approximately 30% for fibroblasts and 10% for melanocytes was observed. Simultaneous exposure of melanocytes and fibroblasts to HCT or FUR and UVAR caused a decrease in cell viability, and number, which was confirmed by microscopic assessment of morphology. The phototoxic effect of HCT and FUR was associated with the disturbance of redox homeostasis confirming the oxidative stress as a mechanism of phototoxic reaction. UVA-irradiated drugs increased the generation of ROS by 10–150%, and oxidized intracellular thiols. A reduction in mitochondrial potential of almost 80% in melanocytes exposed to HCT and UVAR and 60% in fibroblasts was found due to oxidative stress occurrence. In addition, HCT and FUR have been shown to disrupt the cell cycle of normal skin cells. Finally, it can be concluded that HCT is the drug with a stronger phototoxic effect, and fibroblasts turn out to be more sensitive cells to the phototoxic effect of tested drugs. Full article

Melanocytes are essential for skin homeostasis and protection, and their loss or misfunction leads to a wide spectrum of diseases. Cell therapy utilizing autologous melanocytes has been used for years as an adjunct treatment for hypopigmentary disorders such as vitiligo. However, these approaches are hindered by the poor proliferative capacity of melanocytes obtained from skin biopsies. Recent advances in the field of human pluripotent stem cells have fueled the prospect of generating melanocytes. Here, we have developed a well-characterized method to produce a pure and homogenous population of functional and proliferative melanocytes. The genetic stability and potential transformation of melanocytes from pluripotent stem cells have been evaluated over time during the in vitro culture process. Thanks to transcriptomic analysis, the molecular signatures all along the differentiation protocol have been characterized, providing a solid basis for standardizing the protocol. Altogether, our results promise meaningful, broadly applicable, and longer-lasting advances for pigmentation disorders and open perspectives for innovative biotherapies for pigment disorders. Full article

Melanogenesis is a major part of the environmental responses and tissue development of the integumentary system. The balance between reduction and oxidation (redox) governs pigmentary responses, for which coordination among epidermal resident cells is indispensable. Here, we review the current understanding of melanocyte biology with a particular focus on the “master regulator” of oxidative stress responses (i.e., the Kelch-like erythroid cell-derived protein with cap‘n’collar homology-associated protein 1-nuclear factor erythroid-2-related factor 2 system) and the autoimmune pigment disorder vitiligo. Our investigation revealed that the former is essential in pigmentogenesis, whereas the latter results from unbalanced redox homeostasis and/or defective intercellular communication in the interfollicular epidermis (IFE). Finally, we propose a model in which keratinocytes provide a “niche” for differentiated melanocytes and may “imprint” IFE pigmentation. Full article

The discovery of melanocortins in 1916 has resulted in more than 100 years of research focused on these peptides. Extensive studies have elucidated well-established functions of melanocortins mediated by cell surface receptors, including MSHR (melanocyte-stimulating hormone receptor) and ACTHR (adrenocorticotropin receptor). Subsequently, three additional melanocortin receptors (MCRs) were identified. Among these five MCRs, MC3R and MC4R are expressed primarily in the central nervous system, and are therefore referred to as the neural MCRs. Since the central melanocortin system plays important roles in regulating energy homeostasis, targeting neural MCRs is emerging as a therapeutic approach for treating metabolic conditions such as obesity and cachexia. Early efforts modifying endogenous ligands resulted in the development of many potent and selective ligands. This review focuses on the ligands for neural MCRs, including classical ligands (MSH and agouti-related peptide), nonclassical ligands (lipocalin 2, β-defensin, small molecules, and pharmacoperones), and clinically approved ligands (ACTH, setmelanotide, bremelanotide, and several repurposed drugs). Full article