Search Results (340)

Skin dullness contributes to a fatigued and aged appearance, often exceeding one’s biological age. It is a common dermatological concern influenced by aging and poor lifestyle habits, regardless of ethnicity or age. This study aimed to examine advanced glycation end products (AGEs) and their receptor (receptor for AGEs [RAGE]) as contributing factors to skin dullness. AGEs themselves have a yellowish hue, contributing to “yellow dullness.” Additionally, AGE–RAGE signaling promotes melanin production in melanocytes and impairs keratinocyte differentiation as a result of inflammation. Therefore, regulating the AGE–RAGE interaction may help reduce skin dullness. Through screening various natural ingredients, we found that peony root extract (PRE) inhibits AGE formation and blocks AGE–RAGE binding. Furthermore, the presence of PRE leads to the suppression of AGE-induced melanin production in melanocytes and the restoration of impaired keratinocyte differentiation in glycated basement membrane components. In a human clinical study, topical application of a 1% PRE-containing lotion for 2 weeks significantly reduced melanin content, with a trend toward decreased AGE accumulation and visible spots on the cheeks. These findings support the potential of PRE as a multifunctional cosmetic ingredient that comprehensively addresses skin dullness by modulating the AGE–RAGE interaction. Full article

Background/Objectives: Cutaneous melanoma is one of the aggressive forms of skin cancer originating from melanocytes. The high incidence of melanoma metastasis continues to rise, partly due to the complex nature of the molecular mechanisms driving its progression. While melanomas generally arise from melanocytes, we investigated whether aberrant keratinocyte differentiation pathways—like cornified envelope formation—discriminate primary melanoma from metastatic melanoma, revealing novel biomarkers in progression. Methods: In the present study, we retrieved four datasets (GSE15605, GSE46517, GSE8401, and GSE7553) associated with primary and metastatic melanoma tissues and identified differentially expressed genes (DEGs). Thereafter, an integrated meta-analysis and functional enrichment analysis of the DEGs were performed to evaluate the molecular mechanisms involved in melanoma metastasis, such as immune cell deconvolution and protein-protein interaction (PPI) network construction. Hub genes were identified based on four topological methods, including ‘Betweenness’, ‘MCC’, ‘Degree’, and ‘Bottleneck’. We validated the findings using the TCGA-SKCM cohort. Drug-gene interactions were evaluated using the DGIdb, whereas structural druggability was assessed using the ProteinPlus and AlphaFold databases. Results: We identified a total of eleven hub genes associated with melanoma progression. These included members of the keratin gene family (e.g., KRT5, KRT6A, KRT6B, etc.). Except for the gene CDH1, all the hub genes were downregulated in metastatic melanoma tissues. From a prognostic perspective, these hub genes were associated with poor prognosis (i.e., unfavorable). Using the Human Protein Atlas (HPA), immunohistochemistry evaluation revealed mostly undetected levels in metastatic melanoma. Additionally, the cornified envelope formation was the most enriched pathway, with a gene ratio of 17/33. The tumor microenvironment (TME) of metastatic melanomas was predominantly enriched in NK cell–associated signatures. Finally, several hub genes demonstrated favorable druggable potential for immunotherapy. Conclusions: Through integrated meta-analysis, this study identifies transcriptional, immunological, and structural pathways to melanoma metastasis and highlights keratin family genes as promising biomarkers for therapeutic targeting. Full article

Aldehyde dehydrogenase 2 (ALDH2) is a crucial detoxifying enzyme that eliminates toxic aldehydes. ALDH2 deficiency has been linked to various human diseases, including certain cancers. We have previously reported ALDH2 downregulation in human melanoma tissues. Here, we further investigated the biological significance of ALDH2 downregulation in this malignancy. Analysis of TCGA dataset revealed that low ALDH2 expression correlates with poorer survival in metastatic melanoma. Examination of human metastatic melanoma cell lines confirmed that most had ALDH2 downregulation (ALDH2-low) compared to primary melanocytes. In contrast, a small subset of metastatic melanoma cell lines exhibited normal ALDH2 levels (ALDH2-normal). CRISPR/Cas9-mediated ALDH2 knockout in ALDH2-normal A375 cells promoted tumor growth and MAPK/ERK activation. Given the pivotal role of MAPK/ERK signaling in melanoma and cellular response to acetaldehyde, we compared A375 with ALDH2-low SK-MEL-28 and 1205Lu cells. ALDH2-low cells were intrinsically resistant to BRAF and MEK inhibitors, whereas A375 cells were not. However, A375 cells acquired resistance upon ALDH2 knockout. Furthermore, melanoma cells with acquired resistance to these inhibitors displayed further ALDH2 downregulation. Our findings indicate that ALDH2 downregulation contributes to melanoma progression and therapy resistance in BRAF-mutated human metastatic melanoma cells, highlighting ALDH2 as a potential prognostic marker and therapeutic target in metastatic melanoma. Full article

Background: Melanoma is a malignant tumor of melanocytes with an increasing incidence worldwide. Plant-based products are rich in bioactive compounds, offering low toxicity and accessible alternatives for melanoma treatment. A biotechnological approach to obtaining plant-derived produce ensures continuous and high-yield production of medicinally valuable biomass. Objectives: This study aimed to induce and optimize the growth of homogenous callus cultures of Kickxia elatine (L.) Dumort., consequently established a cell suspension culture with a high biomass growth rate, analyzed the phytochemical compositions, and assessed the cytotoxic activity against melanoma cells. Methods/Results: Callus cultures were induced under controlled in vitro conditions on Murashige and Skoog (MS) media supplemented with 2.0 mg L⁻¹ Dicamba and 2.0 mg L⁻¹ 2,4-Dichlorophenoxyacetic acid. The selected callus lines exhibited a high growth index (351.71% ± 27.77) and showed a homogeneous morphology, beige colour, and had friable and watery characteristics. A combination of auxin and cytokinin was found to enhance biomass production significantly. Phytochemical investigations putatively annotated major compounds, including benzoic acid derivatives, phenolic glycosides, phenylpropanoic acids, hydroxycinnamic acid derivatives, and tyrosol derivatives. Methanolic extract (KE-Ex) and 40% methanolic fraction (KE-40Fr) were prepared and tested for cytotoxicity against human fibroblast (MRC-5) and melanoma (MeWo) cell lines using direct cell counting and MTT assay. The crude extract exhibited the strongest cytotoxicity effect on MeWo cells, with IC₅₀ values of 125 ± 8 µg mL⁻¹ after 48 h and 117 ± 7 µg mL⁻¹ after 72 h of treatment. Conclusions: The extract demonstrated a time- and dose-dependent cytotoxic effect, making it a potential candidate for melanoma treatment. Full article

Human cutaneous malignant melanoma is a skin cancer that develops from melanocytes, the cells specialised in the production of eu- and pheomelanin. A growing body of evidence suggests that pheomelanin in particular is involved in melanoma development. The aim of this study was to develop a new method enabling the determination of the pheomelanin in formalin-fixed paraffin-embedded (FFPE) tissue specimens of human nodular (NM) and superficial spreading (SSM) melanomas. The pheomelanin level was evaluated in a small amount of material obtained from FFPE melanoma samples (less than 1 mg), using a multi-step procedure of paraffin removal, tissue rehydration, and homogenisation, omitting the melanin isolation step. The obtained product was studied for pheomelanin content using the Py-GC/MS/MS method operating in a multiple reaction monitoring (MRM) mode. The results of our research confirmed the presence of all the pheomelanin markers in the FFPE human melanoma specimens and showed that the tissues analysed contained different amounts of pheomelanin isomers (5-S-cysteinylDOPA and 2-S-cysteinylDOPA). The developed Py-GC/MS/MS procedure enables sensitive quantification of pheomelanin in FFPE human melanoma samples, facilitating broader studies on its role in melanoma development and progression. This method opens new avenues for investigating pheomelanin’s involvement in melanoma malignancy. Full article

Background/Objectives: Telomerase plays a vital role in preserving telomere length, a key process in cancer development. Human telomerase reverse transcriptase (hTERT) is commonly expressed in various cancers, including melanoma. This study evaluated hTERT protein expression in melanomas compared to melanocytic nevi. Methods: In total, we examined 75 melanocytic lesions using TERT immunohistochemistry on paraffin-embedded tissues; 36 of them were thin melanomas (Breslow index ≤ 1 mm) and 39 melanocytic nevi. Results: The TERT expression differed with statistical significance between the two studied groups, melanomas and melanocytic nevi, in all three aspects examined: percentage of staining (p = 0.006), intensity of staining (p = 0.035), and localisation of staining (p = 0.012). Three quarters of the melanomas stained in over 50% of the cells at cytoplasmic level, 52.78% of the melanomas exhibited an intensity of 3+, and all melanomas were stained at the cytoplasmic level, except for the two negative cases. The values were lower in the melanocytic nevi group. Still, the diagnostic values were relatively low (sensitivity = 75%, specificity = 58.97%, PPV = 62.79%, NPV = 71.88%, and ACC = 66.67%). Conclusions: TERT immunohistochemistry differed between the two studied groups; however, the diagnostic utility is low in our study. Combining with other immunohistochemical antibodies would probably increase the diagnostic power. Full article

Although melanin is viewed as a natural sunscreen that protects pigmented cells against the adverse effects of solar radiation, recent studies have demonstrated that, under certain conditions, the pigment can actually contribute to light-induced oxidative damage of the cells. However, the main issue with such studies is finding natural pigments without photooxidative modifications. Recently, melanin obtained from melanocytes, generated from human induced pluripotent stem cells (hiPSC-Mel), was suggested as a promising source of the pigment without significant photooxidation. Although different studies have demonstrated the feasibility of the above-mentioned technique to obtain melanin-producing cells, no thorough analysis of the physicochemical properties of the pigment has been performed. To address this issue, we examined the key physicochemical parameters, including the aerobic photoreactivity of melanin isolated from hiPSC-Mel and compared them with those of melanin from other known sources of the pigment, such as bovine retinal pigment epithelium (bRPE) and phototype V (PT-V) hair. Electron paramagnetic resonance (EPR) spectroscopy, dynamic light scattering, UV–Vis absorption and HPLC analysis of melanin degradation products were used. The ability of the examined melanins to photogenerate reactive oxygen species was determined by employing EPR oximetry, EPR spin-trapping and time-resolved singlet oxygen phosphorescence. Although the results of such measurements demonstrated that melanin obtained from hiPSC-Mel exhibited the physicochemical properties typical for eumelanin, a contribution from pheomelanin with a substantial presence of benzothiazine subunits, was also evident. Importantly, the hiPSC-Mel pigment had significantly lower photoreactivity compared to bRPE melanin and PT-V hair melanin. Our findings indicate that hiPSC-Mel could be an excellent source of high-quality pigment for photoprotection studies. Full article

Background/Objectives: This study aims to investigate the effects of 5,7-dihydroxy-4-methylcoumarin (5,7D-4MC) on melanogenesis in B16F10 murine melanoma cells and to evaluate its safety as a potential ingredient for functional cosmetics and therapeutic agents targeting pigmentation-related disorders. Method: The cytotoxicity of 5,7D-4MC was assessed using an MTT assay, and melanin content and tyrosinase activity were measured at different concentrations (25, 50, 100 µM). Western blot analyses were conducted to evaluate the expression of key melanogenesis-related proteins (TYR, TRP-1, TRP-2, and MITF) and to investigate the regulation of major signaling pathways, including PKA/cAMP, GSK3β, and PI3K/AKT. Additionally, a human primary skin irritation test was performed on 32 participants to assess the dermatological safety of 5,7D-4MC. Results: 5,7D-4MC did not affect cell viability at concentrations below 100 µM and significantly promoted melanin production in a dose-dependent manner. Tyrosinase activity and the expression levels of melanogenic proteins increased significantly following 5,7D-4MC treatment. PKA and GSK3β pathways were activated, while the PI3K/AKT pathway was downregulated. The skin irritation test showed that 5,7D-4MC exhibited low irritation potential at concentrations of 50 µM and 100 µM. Conclusions: 5,7D-4MC enhances melanogenesis and demonstrates low skin irritation, making it a promising candidate for therapeutic applications in treating hypopigmentation disorders, such as vitiligo, as well as a functional cosmetic ingredient. However, further studies involving human melanocytes and clinical trials are required to validate their efficacy. Full article

Background/Objectives: Oleuropein (OLP), the key bioactive in olive leaf extracts, has demonstrated various biological benefits. We previously reported on the pro-melanogenic action with increased dendricity of a patented olive leaf extract (Benolea^®) that was standardized to 16–24% OLP. In this study, purified OLP was evaluated to identify if it might be the bioactive responsible for the stimulating effects on melanocytes. Moreover, previous studies on OLP have never reported the effects on melanocyte dendricity or melanin export in the medium. Methods: Herein, the effect of OLP on melanogenesis was first evaluated using the B16F10 cell model and validated using the physiological model of normal human melanocytes from Caucasian (lightly pigmented; LP) and Asian (moderately pigmented; MP) skin. The effects of OLP on melanin export in LP and MP cells were indirectly evaluated by dendricity indices. Results: OLP lowered the intracellular melanin content in B16F10 cells by 26.36%, 24.48%, and 27.71% at 100, 150, and 200 µg/mL (all p < 0.01), respectively, with no effect on the intracellular melanin contents of LP or MP cells. OLP treatment did not influence tyrosinase activity in B16F10 cells or MP cells but significantly enhanced the activity in LP cells. The measurement of extracellular melanin showed significantly higher levels for all three cells, although the levels were considerably higher in MP cells, after the adjustment for OLP autoxidation observed in the cell-free system, which caused melanin-like brown coloration. Furthermore, OLP induced morphological alterations of extended dendrites of B16F10 cells that were retained in LP and MP cells. The quantitation of the dendricity of cells treated with OLP at 200 μg/mL revealed that the total dendrite length was increased by 35.24% (p < 0.05) in LP cells and by 58.45% (p < 0.001) in MP cells without any change in the dendrite number. Conclusions: This is the first study to demonstrate the novel finding that OLP possesses a hitherto unreported unique capacity to stimulate melanocyte dendricity, hence establishing the efficacy for use in increasing human pigmentation. Our findings show significance, with a potential application of the compound OLP for addressing human hypopigmentation disorders in clinical settings or for cosmetic uses related to sunless tanning. Full article

Melanoma is one of the most lethal cancers originating from melanocytes. Its incidence and mortality have been rising rapidly for several decades and have posed a serious threat to human health. Current melanoma treatments are hindered by the scope of application, low efficiency, high cost, and toxic side effects. Due to their affordability and minimal side effects, natural bioactive compounds derived from plants are promising candidates for melanoma treatment. This study aims to delve into the isolation, purification, and characterization of potato proteins and to explore their potential in melanoma treatment. Two potato proteins, patatin PP-1 and aspartate protease inhibitor PP-2, were isolated and purified by a newly developed method in this work, and their physicochemical properties were systematically characterized. Both potato proteins showed great antiproliferative activities and migration inhibition effects on melanoma cells. Meanwhile, Western blotting results illustrated that they could induce endogenous cell apoptosis by regulating the Bax/Bcl-2 pathway. Notably, aspartate protease inhibitor PP-2 demonstrated the best performance in inhibiting the growth and migration of melanoma cells, which might be attributed to the combined effect of its significant antioxidative activity and the inhibition effect of certain necessary protease activities in melanoma. This study provides valuable insights for developing nutraceuticals and therapeutic strategies against melanoma, which can lead to breakthroughs in melanoma treatment. Full article

Background/Objectives: Flavones, a class of plant-based flavonoids, have demonstrated conflicting anti-melanogenic activities in mouse and human melanocytes. Sinensetin (SNT), a polymethoxyflavone, has shown pro-melanogenic activity in B16F10 mouse melanoma (MM) cells, while eupatilin (EU) and jaceosidin (JAC), two flavones that are structural analogs of SNT, have not been evaluated for their effects on melanogenesis yet. Methods: Herein, the effects of SNT, EU, and JAC on melanogenesis in MNT-1 cells (human melanoma) and HEMn-DP cells (primary human melanocytes) have been examined. The mushroom tyrosinase (TYR) activity was tested in cell-free conditions, followed by examination of the cytotoxicity of the compounds via the Alamar Blue (AB) assay. Cellular melanin production and TYR activity were estimated in MNT-1 cells. The compounds were further examined in primary human melanocytes for melanin production, TYR activity, and protein levels. Results: Our findings show that SNT was a potent inhibitor of TYR activity in a cell-free assay, while EU and JAC had no effect. However, both SNT and EU were shown to exhibit anti-melanogenic activity (that was reversible) in human cells, while JAC was ineffective and cytotoxic. Conclusions: SNT and EU are potential novel candidates for hyperpigmentation treatment without cytotoxicity. Additional studies are warranted to elucidate the signaling mechanisms that govern their anti-melanogenesis action. Future research is necessary to assess the anti-melanogenic effectiveness of SNT/EU using 3D skin tissue equivalents and to select the optimal candidate. Full article

Cell culture in two dimensions has been the main instrument in cellular and molecular biology. But there are limitations to two-dimensional culture when it comes to tissue engineering and in vivo reproduction. Tissue engineering technology enabled the creation of biomedical scaffolds, which are mostly utilized to biofabricate different artificial human organs. Tissue architecture that encourage cell proliferation can be produced using direct bioprinting technology. The development of bioinks for 3D bioprinting is consistently seen as a problem in the domains of biofabrication and tissue engineering. This study aimed to determine if Fibroblasts and Keratinocytes could grow on hydrogel scaffolds as efficiently as they can in the culture plates. Melanocytes were co-cultured, and the production of melanin was assessed in a two- and three-dimensional culture system. Scaffolds were fabricated using 8% alginate and 6% gelatin and 3D-printed using a cell link printer. FTIR was used to determine the precise composition of the gels. SEM analysis was performed for the cells present in gel and the topology of the cells. In addition, 8% alginate and 6% alginate gel scaffolds were analyzed for swelling and degradation over time in the cell growth medium and PBS. Furthermore, a gene expression study of cell cultures on scaffolds was performed through qPCR. A live/dead assay was performed to determine cell viability for cells grown on scaffolds for 7, 14, and 21 days. Most of the cells were shown to be viable, similar to the control cells grown on a plate. The findings from the SEM showed that cells were grown on the gel surface, remained viable even after 21 days, and displayed circular cells stacked three-dimensionally on the gel surface in the 3D scaffold. The MTT assay was performed to check the viability of cells cultured on a 3D-printed scaffold for 1, 5, and 15 days. We observed about 40% viable cells after 15 days, as shown by the MTT assay. Furthermore, a co-culture study with Melanocyte showed an increased production of melanin in a 3D culture as compared to a 2D culture. Our findings suggest that an alginate and gelatin polymer can be used as a cellular matrix for epithelial cell culture. Further, in vivo and ex vivo experiments are needed to validate the results for future applications in tissue engineering for wound healing and other tissue engineering domains. Full article

(1) Malignant melanoma is the most aggressive type of malignant tumor caused by a dysfunction of melanocytes. Despite progress in the treatment of melanoma, further research and search for new potential drugs are necessary to optimize the therapy. (2) The aim of this study was to evaluate the antiproliferative activity of eight selected monoterpenes by MTT and LDH assays on four malignant melanoma cell lines. (3) Myrcene, rhodinol and nerol did not show any significant anticancer effect on melanoma cell lines, but citral, carvacrol, citronellol, thymol and geraniol showed a significant anti-viability effect. Our studies have shown that the most effective terpene among those tested in inhibiting melanoma cell viability was carvacrol, with the lowest IC50 in the range of 0.05 ± 0.00 to 0.06 ± 0.01 mM. Moreover, it did not negatively affect normal human keratinocyte cells. (4) Metastatic melanoma is very difficult to treat, and some terpenes have the ability to sensitize cells to other chemicals; so, it is worth investigating their antimelanoma potential, as terpenes could become an adjuvant to traditional treatment. Full article

Hair graying is one of the common visible signs of human aging, resulting from decreased or abolished melanogenesis due to the depletion of melanocyte stem cells through excess accumulation of oxidative stress. Cell-free therapy using a conditioned medium (CM) of mesenchymal stem cells has been highlighted in the field of regenerative medicine owing to its potent therapeutic effects with lower regulatory hurdles and safety risk. Recently, we demonstrated that a CM of an immortalized stem cell line from human exfoliated deciduous teeth (SHED) has protective effects against a mouse model of ulcer formation via antioxidative and angiogenic activities mediated by HGF and VEGF. However, to date, no effective treatments for hair graying have been developed, and the effect of SHED-CM on hair graying remains unknown. In this study, we have investigated the effect of SHED-CM on a hair graying mouse model caused by X-ray irradiation. Repetitive subcutaneous administrations of SHED-CM greatly suppressed the development of hair graying, when compared to control medium, resulting in reduced cutaneous expression of 8-hydroxy-2′-deoxyguanosine, the major product of DNA damage induced by reactive oxygen species. Consistent with these in vivo results, SHED-CM significantly inhibited the cell death caused by X-ray irradiation in melanoma cell line B16F10 cells. Immunodepletion of HGF or VEGF in the SHED-CM revealed that this inhibition was due to suppression of the generation of reactive oxygen species, which was mainly mediated by HGF and probably VEGF. These results suggest that SHED-CM has protective effects against hair graying via its antioxidative activity. Full article

Little is known about the anti-graying effects of antioxidants on hair. The anti-graying effects of three antioxidants (luteolin, hesperetin, and diosmetin) on hair were investigated according to the sequential processes of hair graying that were previously clarified in model mice [Ednrb(+/−);RET-mice]. External treatment with luteolin, but not that with hesperetin or diosmetin, alleviated hair graying in Ednrb(+/−);RET-mice. Internal treatment with luteolin also mitigated hair graying in the mice. Although both luteolin treatments had very limited effects on hair cycles, the treatments suppressed the increase in p16^ink4a-positive cells in bulges [senescent keratinocyte stem cells (KSCs)]. Both of the treatments also suppressed decreases in the expression levels of endothelins in KSCs and their receptor (Ednrb) in melanocyte stem cells (MSCs) and alleviated hair graying in the mice. Luteolin is a special antioxidant with an anti-graying potency through improvement of age-related dysfunction in signaling between endothelins in KSCs and their receptor in MSCs. Luteolin for topical and oral use is commercially available to people in the form of supplements. Similar processes of hair graying in Ednrb(+/−);RET-mice and humans have been reported. These results are encouraging for the practical application of luteolin as a medicine with an anti-graying effect on hair in humans. Full article