The melanoma revolution: from UV carcinogenesis to a new era in therapeutics

Ultrafast excited-state energy dissipation pathway of diethylamino hydroxybenzoyl hexyl benzoate (DHHB) via the nanoparticles

The organic UVA filter is popularized in sunscreen cosmetics due to the advantages of excellent light stability and high molar extinction coefficient. However, the poor water solubility of organic UV filters has been a common problem. Given that nanoparticles (NPs) can significantly improve the water solubility of organic chemicals. Meanwhile, the excited-state relaxation pathways of NPs might differ from their solution. Here, the NPs of diethylamino hydroxybenzoyl hexyl benzoate (DHHB), a popular organic UVA filter, were prepared by an advanced ultrasonic micro-flow reactor. The surfactant (sodium dodecyl sulfate) was selected as an effective stabilizer to prevent the self-aggregation of the NPs for DHHB. Femtosecond transient ultrafast spectroscopy (fs-TA) and theoretical calculations were utilized to trace and explain the excited-state evolution of DHHB in NPs suspension and its solution. The results reveal that the surfactant-stabilized NPs of DHHB reserve a similarly good performance of ultrafast excited-state relaxation. The stability characterization experiments demonstrate that the strategy of surfactant-stabilized NPs for sunscreen chemicals can maintain its stability and enhance the water solubility of DHHB compared with that of the solution phase. Therefore, the surfactant-stabilized NPs of organic UV filters are an effective method to improve water solubility and keep the stability from aggregation and photoexcitation.

A self-monitoring microneedle patch for light-controlled synergistic treatment of melanoma

Melanoma is the most aggressive and malignant form of skin cancer. Current melanoma treatment methods generally suffer from frequent drug administration as well as difficulty in direct monitoring of drug release. Here, a self-monitoring microneedle (MN)-based drug delivery system, which integrates a dissolving MN patch with aggregation-induced emission (AIE)-active PATC microparticles, is designed to achieve light-controlled pulsatile chemo-photothermal synergistic therapy of melanoma. The PATC polymeric particles, termed D/I@PATC, encapsulate both of chemotherapeutic drug doxorubicin (DOX) and the photothermal agent indocyanine green (ICG). Upon light illumination, PATC gradually dissociates into smaller particles, causing the release of encapsulated DOX and subsequent fluorescence intensity change of PATC particles, thereby not only enabling direct observation of the drug release process under light stimuli, but also facilitating verification of drug release by fluorescence recovery after light trigger. Moreover, encapsulation of ICG in PATC particles displays significant improvement of its photothermal stability both in vitro and in vivo. In a tumor-bearing mouse, the application of one D/I@PATC MN patch combining with two cycles of light irradiation showed excellent controllable chemo-photothermal efficacy and exhibited ∼97% melanoma inhibition rate without inducing any evident systemic toxicity, suggesting a great potential for skin cancer treatment in clinics.

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

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

Identification of SNPs in MITF associated with beak color of duck

Introduction: Beak color-a pigment-related trait-is an important feature of duck breeds. Recently, little research has addressed genetic mechanism of the beak colors in poultry, whereas the process and the regulation factors of melanin deposition have been well described. Methods: To investigate the genetic mechanism of beak colors, we conducted an integrated analysis of genomic selection signatures to identify a candidate site associated with beak color. For this, we used black-billed (Yiyang I meat duck synthetic line H1, H2, H3&HF) and yellow-billed ducks (Cherry Valley ducks and white feather Putian black duck). Quantitative real-time PCR and genotyping approaches were used to verify the function of the candidate site. Results: We identified 3,895 windows containing 509 genes. After GO and KEGG enrichment analysis, nine genes were selected. Ultimately, MITF was selected by comparing the genomic differentiation (FST). After loci information selection, 41 extreme significantly different loci were selected, which are all located in intron regions of MITF and are in almost complete linkage disequilibrium. Subsequently, the site ASM874695v1:10:g.17814522T > A in MITF was selected as the marker site. Furthermore, we found that MITF expression is significantly higher in black-beaked ducks than in yellow-beaked ducks of the F2 generation (p < 0.01). After genotyping, most yellow-billed individuals are found with homozygous variant; at the same time, there are no birds with homozygous variant in black-billed populations, while the birds with homozygous and heterozygous variant share the same proportion. Conclusion: MITF plays a very critical role in the melanogenesis and melanin deposition of duck beaks, which can effectively affect the beak color. The MITF site, ASM874695v1:10:g.17814522T > A could be selected as a marker site for the duck beak color phenotype.

Human-Hair-Derived Natural Particles as Multifunctional Sunscreen for Effective UV Protection

Excessive ultraviolet (UV) radiation can lead to a series of skin problems. Although commercial sunscreens can protect skin from UV-induced damage to an extent, the side effects caused by such products are still worrisome. Here, inspired by the natural photoprotection effect of human hair, we extracted the multifunctional particles from human hair as sunscreens for UV protection. Both in vitro and in vivo results indicate that hair-derived particles (HDPs) could effectively protect skin from UV radiation. Besides, HDPs retain the antioxidant capability of melanin in hair, which avoids UV-induced oxidative damage. In addition, the unique shape of HDPs can prevent them from penetrating into the skin, thus avoiding potential toxicity. Moreover, owing to their mesoporous structure, the particles can also be used as drug carriers. With the loading of octocrylene, the particles are more effective in blocking UV radiation. This study provides an ingenious tactic for the design and development of sunscreens from a natural substance.

Melanocortin 1 Receptor (MC1R): Pharmacological and Therapeutic Aspects

Melanocortins play crucial roles in regulating the stress response, inflammation, and skin pigmentation. In this review, we focus on the melanocortin 1 receptor (MC1R), a G protein-coupled receptor primarily known for regulating skin pigmentation and exhibiting anti-inflammatory effects. First, we provide an overview of the structure, signaling pathways, and related diseases of MC1R. Next, we discuss the potential therapeutic use of synthetic peptides and small molecule modulators of MC1R, highlighting the development of various drugs that enhance stability through amino acid sequence modifications and small molecule drugs to overcome limitations associated with peptide characteristics. Notably, MC1R-targeted drugs have applications beyond skin pigmentation-related diseases, which predominantly affect MC1R in melanocytes. These drugs can also be useful in treating inflammatory diseases with MC1R expression present in various cells. Our review underscores the potential of MC1R-targeted drugs to treat a wide range of diseases and encourages further research in this area.

A novel cell-wall polysaccharide derived from the stipe of Agaricus bisporus inhibits mouse melanoma proliferation and metastasis

Malignant melanoma is an invasive and highly aggressive skin cancer that-if diagnosed-poses a serious threat to the patient's health and life. In this work, a novel purified cell-wall polysaccharide (termed Abwp) was obtained from the discarded stipe of Agaricus bisporus (A. bisporus) and characterized to be a novel homogeneous polysaccharide consisted of a β-(1 → 4)- glucosyl backbone with β-(1 → 2) and (1 → 6)-d-glucosyl side-chains. The anti-melanoma effects of Abwp and its associated mechanisms in mice were then explored using in vitro and in vivo approaches. In vitro results showed that Abwp inhibited B16 melanoma cell proliferation and promoted their apoptosis in both time- and dose-dependent manners. In B16 cells induced with tumor necrosis factor (TNF-α), Abwp significantly decreased the protein expression of inflammatory-related signaling pathway (e.g., p38 MAPK and NF-κB) in time-, concentration-, and dose-dependent manners. Moreover, Abwp blocked nuclear entry of NF-κB-p65. In an in vivo mouse model featuring neoplasm transplantation with B16 melanoma cells, Abwp significantly inhibited the growth and proliferation of mouse melanoma. Hematoxylin staining showed that the invasion of melanoma cells into the lung tissue of the Abwp-treated group was significantly reduced. Immunohistochemical analysis showed that the expression of proliferation cell nuclear antigen (PCNA), N-cadherin, MMP-9, and Snail in the lung of mouse was significantly inhibited. Immunofluorescence showed that Abwp significantly interfered with the nuclear transcription of NF-κB-p65 in a dose-dependent manner. Collectively, these results showed that Abwp mediated p38 MAPK and NF-κB signaling pathways to inhibit the inflammatory response and malignant proliferation and metastasis of melanoma in mice.

Pharmacological inhibition of EZH2 by ZLD1039 suppresses tumor growth and pulmonary metastasis in melanoma cells in vitro and in vivo

The incidence and mortality rate of malignant melanoma are increasing worldwide. Metastasis reduces the efficacy of current melanoma therapies and leads to poor prognosis for patients. EZH2 is a methyltransferase that promotes the proliferation, metastasis, and drug resistance of tumor cells by regulating transcriptional activity. EZH2 inhibitors could be effective in melanoma therapies. Herein, we aimed to investigate whether the pharmacological inhibition of EZH2 by ZLD1039, a potent and selective S-adenosyl-l-methionine-EZH2 inhibitor, suppresses tumor growth and pulmonary metastasis in melanoma cells. Results showed that ZLD1039 selectively reduced H3K27 methylation in melanoma cells by inhibiting EZH2 methyltransferase activity. Additionally, ZLD1039 exerted excellent antiproliferative effects on melanoma cells in 2D and 3D culture systems. Administration of ZLD1039 (100 mg/kg) by oral gavage caused antitumor effects in the A375 subcutaneous xenograft mouse model. RNA sequencing and GSEA revealed that the ZLD1039-treated tumors exhibited changes in the gene sets enriched from the "Cell Cycle" and "Oxidative Phosphorylation", whereas the "ECM receptor interaction" gene set had a negative enrichment score. Mechanistically, ZLD1039 induced G0/G1 phase arrest by upregulating p16 and p27 and inhibiting the functions of the cyclin D1/CDK6 and cyclin E/CDK2 complexes. Moreover, ZLD1039 induced apoptosis in melanoma cells via the mitochondrial reactive oxygen species apoptotic pathway, consistent with the changes in transcriptional signatures. ZLD1039 also exhibited excellent antimetastatic effects on melanoma cells in vitro and in vivo. Our data highlight that ZLD1039 may be effective against melanoma growth and pulmonary metastasis and thus could serve as a therapeutic agent for melanoma.

3D Spheroid Configurations Are Possible Indictors for Evaluating the Pathophysiology of Melanoma Cell Lines

To study the molecular mechanisms responsible for inducing the spatial proliferation of malignant melanomas (MM), three-dimension (3D) spheroids were produced from several MM cell lines including SK-mel-24, MM418, A375, WM266-4, and SM2-1, and their 3D architectures and cellular metabolisms were evaluated by phase-contrast microscopy and Seahorse bio-analyzer, respectively. Several transformed horizontal configurations were observed within most of these 3D spheroids, and the degree of their deformity was increased in the order: WM266-4, SM2-1, A375, MM418, and SK-mel-24. An increased maximal respiration and a decreased glycolytic capacity were observed within the lesser deformed two MM cell lines, WM266-4 and SM2-1, as compared with the most deformed ones. Among these MM cell lines, two distinct cell lines, WM266-4 and SK-mel-24, whose 3D appearances were the closest and farthest, respectively, from being horizontally circular-shaped, were subjected to RNA sequence analyses. Bioinformatic analyses of the differentially expressed genes (DEGs) identified KRAS and SOX2 as potential master regulatory genes for inducing these diverse 3D configurations between WM266-4 and SK-mel-24. The knockdown of both factors altered the morphological and functional characteristics of the SK-mel-24 cells, and in fact, their horizontal deformity was significantly reduced. A qPCR analysis indicated that the levels of several oncogenic signaling related factors, including KRAS and SOX2, PCG1α, extracellular matrixes (ECMs), and ZO1 had fluctuated among the five MM cell lines. In addition, and quite interestingly, the dabrafenib and trametinib resistant A375 (A375DT) cells formed globe shaped 3D spheroids and showed different profiles in cellular metabolism while the mRNA expression of these molecules that were tested as above were different compared with A375 cells. These current findings suggest that 3D spheroid configuration has the potential for serving as an indicator of the pathophysiological activities associated with MM.

Cryptochrome 1 activation inhibits melanogenesis and melanosome transport through negative regulation of cAMP/PKA/CREB signaling pathway

Cutaneous pigmentation was recently shown to be an event regulated by clock proteins. Cryptochrome (CRY) is a key protein composing the feedback loop of circadian clock, however, the function of CRY in melanocytes remains unclear. Here, we found that KL001, a synthetic small molecule modulator of CRY1, inhibited melanin synthesis, as well as reduced melanocyte dendrite elongation and melanosome transport. In addition, the dominant role of CRY1 in KL001-induced anti-melanogenesis was revealed by small interfering RNA transfection. Cellular tyrosinase activity and expression level of melanogenic proteins, including tyrosinase, TRP-1, TRP-2, and transport proteins like Rab27a, Cdc42 and Myosin Va induced by α-MSH were remarkably reversed after KL001 treatment. Mechanistically, CRY1 activation inhibited melanogenesis through CREB-dependent downregulation of MITF and CREB phosphorylation was mediated by classical cAMP/PKA pathway. In addition, the other CRY1 activator, KL044 also suppressed cAMP/PKA/CREB pathway and inhibited melanogenesis. Finally, anti-melanogenic efficacy of KL001 was confirmed by determination of melanin contents in UVB-tanning model of brown guinea pigs, which indicated that targeting CRY1 activity, via topical application of small molecule activator, can be utilized therapeutically to manage human pigmentary disorders.

Serum Neu5Gc biomarkers are elevated in primary cutaneous melanoma

Cutaneous melanoma is one of the most aggressive and deadly types of skin cancer and rates of disease are continuing to increase worldwide. Currently, no serum biomarkers exist for the early detection of cutaneous melanoma. Normal human cells cannot make the sialic acid sugar, Neu5Gc, yet human tumor cells express Neu5Gc and Neu5Gc-containing glycoconjugates have been proposed as tumor biomarkers. We engineered a Neu5Gc-specific lectin based on the pentameric B-subunit of the Shiga toxigenic Escherichia coli subtilase cytotoxin, termed SubB2M. We have detected elevated Neu5Gc-containing biomarkers in the sera of ovarian and breast cancer patients in a highly sensitive surface plasmon resonance (SPR)-based assay using our SubB2M lectin. Here, we used the SubB2M-SPR assay to investigate Neu5Gc-containing glycoconjugates in the serum of cutaneous melanoma patients. We found elevated total serum Neu5Gc levels in primary (n = 24) and metastatic (n = 38) patients compared to cancer-free controls (n = 34). Serum Neu5Gc levels detected with SubB2M can distinguish cutaneous melanoma patients from cancer-free controls with high sensitivity and specificity as determined by ROC curve analysis. These data indicate that serum Neu5Gc-containing glycoconjugates are a novel class of biomarkers for cutaneous melanoma, particularly for primary melanoma, and have the potential to contribute to the early diagnosis of this disease.

Research landscape and trends of melanoma immunotherapy: A bibliometric analysis

Background

Immunotherapy for lung cancer has been a hot research area for years. This bibliometric analysis was intended to present research trends on melanoma immunotherapy.

Method

On April 1, 2022, the authors identified 2,109 papers on melanoma immunotherapy using the Web of Science and extracted their general information and the total number of citations. The authors then conducted a bibliometric analysis to present the research landscape, clarify the research trends, and determine the most cited papers (top-papers) as well as major journals on melanoma immunotherapy. Subsequently, recent research hotspots were identified by analyzing the latest articles in major journals.

Results

The total and median number of citations of these 2,109 papers on melanoma immunotherapy was 137,686 and 11, respectively. "Improved survival with ipilimumab in patients with metastatic melanoma" by Hodi et al. was the most cited paper (9,824 citations). Among the journals, the top-paper number (16), average citations per paper (2,510.7), and top-papers rate (100%) of New England Journal of Medicine were the highest. Corresponding authors represented the USA took part in most articles (784). Since 2016, the hottest research area has changed from CTLA-4 to PD-1.

Conclusions

This bibliometric analysis comprehensively and quantitatively presents the research trends and hotspots based on 2,109 relevant publications, and further suggests future research directions. The researchers can benefit in selecting journals and in finding potential collaborators. This study can help researchers gain a comprehensive impression of the research landscape, historical development, and current hotspots in melanoma immunotherapy and can provide inspiration for future research.

A unique hyperdynamic dimer interface permits small molecule perturbation of the melanoma oncoprotein MITF for melanoma therapy

Microphthalmia transcription factor (MITF) regulates melanocyte development and is the "lineage-specific survival" oncogene of melanoma. MITF is essential for melanoma initiation, progression, and relapse and has been considered an important therapeutic target; however, direct inhibition of MITF through small molecules is considered impossible, due to the absence of a ligand-binding pocket for drug design. Here, our structural analyses show that the structure of MITF is hyperdynamic because of its out-of-register leucine zipper with a 3-residue insertion. The dynamic MITF is highly vulnerable to dimer-disrupting mutations, as we observed that MITF loss-of-function mutations in human Waardenburg syndrome type 2 A are frequently located on the dimer interface and disrupt the dimer forming ability accordingly. These observations suggest a unique opportunity to inhibit MITF with small molecules capable of disrupting the MITF dimer. From a high throughput screening against 654,650 compounds, we discovered compound TT-012, which specifically binds to dynamic MITF and destroys the latter's dimer formation and DNA-binding ability. Using chromatin immunoprecipitation assay and RNA sequencing, we showed that TT-012 inhibits the transcriptional activity of MITF in B16F10 melanoma cells. In addition, TT-012 inhibits the growth of high-MITF melanoma cells, and inhibits the tumor growth and metastasis with tolerable toxicity to liver and immune cells in animal models. Together, this study demonstrates a unique hyperdynamic dimer interface in melanoma oncoprotein MITF, and reveals a novel approach to therapeutically suppress MITF activity.

Retinoblastoma-Binding Protein 5 Regulates H3K4 Methylation Modification to Inhibit the Proliferation of Melanoma Cells by Inactivating the Wnt/β-Catenin and Epithelial-Mesenchymal Transition Pathways

Histone 3 lysine 4 methylation (H3K4me), especially histone 3 lysine 4 trimethylation (H3K4me3), is one of the most extensively studied patterns of histone modification and plays crucial roles in many biological processes. However, as a part of H3K4 methyltransferase that participates in H3K4 methylation and transcriptional regulation, retinoblastoma-binding protein 5 (RBBP5) has not been well studied in melanoma. The present study sought to explore RBBP5-mediated H3K4 histone modification and the potential mechanisms in melanoma. RBBP5 expression in melanoma and nevi specimens was detected by immunohistochemistry. Western blotting was performed for three pairs of melanoma cancer tissues and nevi tissues. In vitro and in vivo assays were used to investigate the function of RBBP5. The molecular mechanism was determined using RT-qPCR, western blotting, ChIP assays, and Co-IP assays. Our study showed that RBBP5 was significantly downregulated in melanoma tissue and cells compared with nevi tissues and normal epithelia cells (P < 0.05). Reducing RBBP5 in human melanoma cells leads to H3K4me3 downregulation and promotes cell proliferation, migration, and invasion. On the one hand, we verified that WSB2 was an upstream gene of RBBP5-mediated H3K4 modification, which could directly bind to RBBP5 and negatively regulate its expression. On the other hand, we also confirmed that p16 (a cancer suppressor gene) was a downstream target of H3K4me3, the promoter of which can directly bind to H3K4me3. Mechanistically, our data revealed that RBBP5 inactivated the Wnt/β-catenin and epithelial-mesenchymal transition (EMT) pathways (P < 0.05), leading to melanoma suppression. Histone methylation is rising as an important factor affecting tumorigenicity and tumor progression. Our findings verified the significance of RBBP5-mediated H3K4 modification in melanoma and the potential regulatory mechanisms of melanoma proliferation and growth, suggesting that RBBP5 is a potential therapeutic target for the treatment of melanoma.

PIK3R2 predicts poor outcomes for patients with melanoma and contributes to the malignant progression via PI3K/AKT/NF-κB axis

BACKGROUND

Melanoma is an aggressive form of skin cancer worldwide. Phosphoinositide-3-kinase regulatory subunit 2 (PIK3R2) exerts carcinogenic roles in various tumors. So far, the function and mechanism of PIK3R2 in melanoma are not been fully clarified.

OBJECTIVE

We aimed to clarify the role of PIK3R2 in melanoma.

METHODS

PIK3R2 expressions in melanoma clinical tissues and melanoma cells were measured using quantitative real-time PCR and Western blot. In addition, PIK3R2 expressions in different tumor stages of melanoma were determined by immunohistochemistry assay. Meanwhile, PIK3R2 function was evaluated using loss or gain-of-function assays, Cell Counting Kit-8 assay, flow cytometry, and Transwell analysis. Furthermore, PIK3R2 mechanism in melanoma was assessed by a series of rescue experiments.

RESULTS

PIK3R2 was highly expressed in melanoma tissues and cells, and PIK3R2 expressions were the highest in Stage IV. Functionally, PIK3R2 knockdown repressed melanoma cell proliferation, invasion, epithelial-mesenchymal transition, and facilitated cell apoptosis. Also, PIK3R2 overexpression produced an opposite trend. Mechanistically, PIK3R2 facilitated melanoma progression by activating PI3K/AKT/NF-κB pathway. Furthermore, PIK3R2 knockdown restrained the melanoma tumor growth in vivo.

CONCLUSIONS

PIK3R2 aggravated melanoma by activating PI3K/AKT/NF-κB pathway, prompting that PIK3R2 might be a therapeutic target for melanoma.

Targeting Wnt/β-Catenin Signaling Exacerbates Ferroptosis and Increases the Efficacy of Melanoma Immunotherapy via the Regulation of MITF

Melanoma is the most lethal form of skin cancer, resulting from the malignant transformation of epidermal melanocytes. Recent revolutionary progress in targeted therapy and immunotherapy has prominently improved the treatment outcome, but the survival of melanoma patients remains suboptimal. Ferroptosis is greatly involved in cancer pathogenesis and can execute the outcome of immunotherapy. However, the detailed regulatory mechanisms of melanoma cell ferroptosis remain elusive. Herein, we report that Wnt/β-catenin signaling regulates ferroptosis and melanoma immunotherapy efficacy via the regulation of MITF. First of all, we found that Wnt/β-catenin signaling was prominently suppressed in melanoma cell ferroptosis. Then, we proved that targeting β-catenin exacerbated melanoma cell ferroptosis by promoting the generation of lipid peroxidation both in vitro and in vivo. Subsequent mechanistic studies revealed that MITF mediated the effect of Wnt/β-catenin signaling on melanoma cell ferroptosis, and PGC1α and SCD1 were documented as two main effectors downstream of Wnt/β-catenin-MITF pathway. Ultimately, pharmacological inhibition of β-catenin or MITF increased the efficacy of anti-PD-1 immunotherapy in preclinical xenograft tumor model by promoting ferroptosis. Taken together, Wnt/β-catenin signaling deficiency exacerbates ferroptosis in melanoma via the regulation of MITF. Targeting Wnt/β-catenin-MITF pathway could be a promising strategy to potentiate ferroptosis and increase the efficacy of anti-PD-1 immunotherapy.

Current understanding of epigenetics role in melanoma treatment and resistance

Melanoma is the most aggressive form of skin cancer resulting from genetic mutations in melanocytes. Several factors have been considered to be involved in melanoma progression, including genetic alteration, processes of damaged DNA repair, and changes in mechanisms of cell growth and proliferation. Epigenetics is the other factor with a crucial role in melanoma development. Epigenetic changes have become novel targets for treating patients suffering from melanoma. These changes can alter the expression of microRNAs and their interaction with target genes, which involves cell growth, differentiation, or even death. Given these circumstances, we conducted the present review to discuss the melanoma risk factors and represent the current knowledge about the factors related to its etiopathogenesis. Moreover, various epigenetic pathways, which are involved in melanoma progression, treatment, and chemo-resistance, as well as employed epigenetic factors as a solution to the problems, will be discussed in detail.

Terminalia catappa leaf extracts inhibited metastasis of A2058 and A375 melanoma cells via downregulating p-Src and β-catenin pathway in vitro

Background: Melanoma is a highly aggressive, lethal, and malignant cancer. Once diagnosed early, it can be easily removed and cured with satisfaction. Although many methods such as surgery, chemotherapy, radiotherapy, and immunotherapy have been used to treat this disease at an advanced stage, the outcomes are poor. Terminalia catappa leaves have been shown to have various biological benefits, including antitumor activity. The specific effects and molecular mechanisms of Terminalia catappa leaf in treating A2058 and A375 melanoma cells in vitro need to be clarified.

Methods: The A2058 and A375 melanoma cancer cells were treated with Terminalia catappa leaf extracts, and then the effect of Terminalia catappa leaf extracts on migration and invasion was examined. The cell migration/invasion capacities of A2058 and A375 cells were investigated by a modified Boyden chamber assay. Zymography was used to clarify the activities of matrix metalloproteinases-2 and urinary type plasminogen activator. We performed a Western blot to verify the related expression of phospho-Src (Tyr416), phospho-Focal adhesion kinase (Tyr397), Vimentin, and β-catenin.

Results: Modified Boyden chamber assays demonstrated that treatment of Terminalia catappa leaf extracts significantly inhibited A2058 and A375 cell migration/invasion capacities. In the zymography results, we showed that Terminalia catappa leaf extracts negatively modulated the activities of matrix metalloproteinases-2 and urinary type plasminogen activator. Western blot indicated that Terminalia catappa leaf extracts reduced the expression of phospho-Src (Tyr416), phospho-Focal adhesion kinase (Tyr397), Vimentin, and β-catenin.

Conclusion:Terminalia catappa leaf extracts affected the antimetastasis of the A2058 and A375 melanoma cell lines by inhibiting the Focal adhesion kinase/Src interaction and Wingless-int1/β-catenin pathways in vitro. Terminalia catappa leaf extracts may serve as an effective chemopreventive agent against metastasis of melanoma cancer.

Comprehensive characterisation of immunogenic cell death in melanoma revealing the association with prognosis and tumor immune microenvironment

Increasing evidence has highlighted the critical functions of immunogenic cell death (ICD) within many tumors. However, the therapeutic possibilities and mechanism of utilizing ICD in melanoma are still not well investigated. Melanoma samples involved in our study were acquired from The Cancer Genome Atlas (TCGA) and the Gene Expression Omnibus (GEO) databases. First, pan-cancer analysis of ICD systematically revealed its expression characteristics, prognostic values, mutation information, methylation level, pathway regulation relationship in multiple human cancers. The non-negative matrix factorization clustering was utilized to separate the TCGA-melanoma samples into two subtypes (i.e. C1 and C2) with different prognosis and immune microenvironment based on the expression traits of ICD. Then, LASSO-Cox regression analysis was utilized to determine an ICD-dependent risk signature (ICDRS) based on the differentially expressed genes (DEGs) between the two subtypes. Principal component analysis and t-distributed stochastic neighbor embedding analysis of ICDRS showed that high- and low-risk subpopulations could be clearly distinguished. Survival analysis and ROC curves in the training, internal validation, and external validation cohorts highlighted the accurate prognosis evaluation of ICDRS. The obvious discrepancies of immune microenvironment between the different risk populations might be responsible for the different prognoses of patients with melanoma. These findings revealed the close association of ICD with prognosis and tumor immune microenvironment. More importantly, ICDRS-based immunotherapy response and targeted drug prediction might be beneficial to different risk subpopulations of patients with melanoma. The innotative ICDRS could function as a marker to determine the prognosis and tumor immune microenvironment in melanoma. This will aid in patient classification for individualized melanoma treatment.

Melanosomal targeting via caveolin-1 dependent endocytosis mediates ZN(II) phthalocyanine phototoxic action in melanoma cells

Melanosomes have been considered crucial targets in melanoma treatments. In this study we explored the role of melanosomes in photodynamic therapy (PDT), employing the synthetic Zn(II) phthalocyanine Pc13, a potent photosensitizer that promotes melanoma cell death after irradiation. Phototoxic action is mediated by reactive oxygen species increase. The internalization mechanism of Pc13 and its consequent subcellular localization were evaluated in melanotic B16-F0 cells. Pharmacological inhibitors of dynamin or caveolae, but not of clathrin, decreased Pc13 cellular uptake and phototoxicity. Similar results were obtained when cells over-expressed dominant negative mutants of dynamin-2 and caveolin-1, indicating that Pc13 is internalized by caveolae-mediated endocytosis. Confocal microscopy analysis revealed that Pc13 targets melanosomes and damage of these structures after irradiation was demonstrated by transmission electron microscopy. Treatment of pigmented B16-F0 and WM35 melanoma cells with the melanin synthesis inhibitor phenylthiourea for 48 h led to cell depigmentation and enhanced cell death after irradiation, whereas a 3-h period of inhibition did not modify melanin content but produced a marked reduction of Pc13 phototoxicity, together with a decrease of oxidative melanin synthesis intermediates. In contrast, the effect of Pc13 in amelanotic A375 cells was not altered by phenylthiourea treatment. These results provide evidence that melanosomes have a dual role in the efficacy of PDT. While melanin antagonizes the phototoxic action of Pc13, the release of cytotoxic synthetic intermediates to cytosol after irradiation and melanosome damage is conducive to the phototoxic response. Based on these findings, we demonstrate that melanosome-targeted PDT could be an effective approach for melanoma treatment.

Melanoma Tumour Vascularization and Tissue-Resident Endothelial Progenitor Cells

The aggressiveness of solid cancers, such as melanoma, relies on their metastatic potential. It has become evident that this key cause of mortality is largely conferred by the tumour-associated stromal cells, especially endothelial cells. In addition to their essential role in the formation of the tumour vasculature, endothelial cells significantly contribute to the establishment of the tumour microenvironment, thus enabling the dissemination of cancer cells. Melanoma tumour vascularization occurs through diverse biological processes. Vasculogenesis is the formation of de novo blood vessels from endothelial progenitor cells (EPCs), and recent research has shown the role of EPCs in melanoma tumour vascularization. A more detailed understanding of the complex role of EPCs and how they contribute to the abnormal vessel structures in tumours is of importance. Moreover, anti-angiogenic drugs have a limited effect on melanoma tumour vascularization, and the role of these drugs on EPCs remains to be clarified. Overall, targeting cancer vasculature remains a challenge, and the role of anti-angiogenic drugs and combination therapies in melanoma, a focus of this review, is an area of extensive exploration.

Skin-Aging Pigmentation: Who Is the Real Enemy?

Skin aging is induced and sustained by chronological aging and photoaging. Aging skin pigmentation such as mottled pigmentation (senile lentigo) and melasma are typical signs of photoaging. The skin, like other human organs, undergoes cellular senescence, and senescent cells in the skin increase with age. The crosstalk between melanocytes as pigmentary cells and other adjacent types of aged skin cells such as senescent fibroblasts play a role in skin-aging pigmentation. In this review, we provide an overview of cellular senescence during the skin-aging process. The discussion also includes cellular senescence related to skin-aging pigmentation and the therapeutic potential of regulating the senescence process.

The molecular mechanisms of vulpinic acid induced programmed cell death in melanoma

BACKGROUNDS

Malignant melanoma is an aggressive skin tumor with a rapidly increasing incidence and there is not yet a successful treatment strategy. Vulpinic acid (VA) is derived from secondary metabolites from lichen species. In the current study, we, for the first time, investigated the anti-cancer effects of VA and the underlying mechanism VA induced programmed cell death in melanoma.

METHODS

The anti-cancer effects of VA on melanoma cells were evaluated by the xCELLigence system, flow cytometry, caspase-3 activity and RT-PCR analysis.

RESULTS

Our results showed that VA had a strong anti-proliferative effect on A-375 melanoma cells without damaging human epidermal melanocyte cells. Additionally, VA promoted apoptotic cell death through G2/M arrest and the activation of both intrinsic and extrinsic apoptosis pathways according to the analysis of 88 genes associated with apoptosis by qRT-PCR.

CONCLUSIONS

Our findings suggest that VA could become an alternative topical and transdermal treatment strategy in the treatment of maligned melanoma cancer. However, further investigations are needed to assess the underlying molecular mechanism of VA mediated apoptotic cell death in the treatment of melanoma.

Vegetable-derived indole enhances the melanoma-treating efficacy of chemotherapeutics

Food-drug interaction is an important but overlooked issue. For example, little is known concerning whether or not the chemotherapy of cancers is affected by the well-defined dietary chemicals such as 2-(indol-3-ylmethyl)-3,3'-diindolylmethane (LTr1) derived from daily consumed cruciferous vegetables. This work, inspired by the described melanogenesis reduction by certain indoles, presents that LTr1 mitigates the melanogenesis and thus potentiates the in vitro and in vivo anti-melanoma effectiveness of different chemotherapeutic agents including dacarbazine, vemurafenib, and sorafenib. In B16 melanoma cells, LTr1 was shown to inhibit the melanogenesis by acting towards the regulatory (R) subunit of protein kinase A (PRKAR1a) associated with the phosphorylation of cAMP-response element binding protein (CREB). This allows LTr1 to reduce the expression of melanogenesis-related enzymes such as tyrosinase (TYR), tyrosinase-related protein 1 (TYRP1), and tyrosinase-related protein 2 (TYRP2). Furthermore, LTr1 was addressed to bind to the aryl hydrocarbon receptor (AhR) and up-regulate the expression of CYP1A1 encoding cytochrome P450 1A1, leading to the escalation of reactive oxygen species (ROS) level. The increased ROS generation promotes the cysteine-to-cystine transformation to inhibit the pheomelanogenesis in melanomas. Collectively, the work identifies LTr1 as a new melanogenesis inhibitor that modulates the PKA/CREB/MITF and AhR/CYP1A1/ROS pathways, thereby providing a new option for (re)sensitizing melanomas to chemotherapeutics.

Survival from cutaneous malignant melanoma is improving, but is it because of a trend in decreasing melanoma thickness or the advent of new 'revolutionary' therapeutics?

Linked Article: Zamagni et al. Br J Dermatol 2022; 187:52–63 .

Nanoparticle delivery of miR-21-3p sensitizes melanoma to anti-PD-1 immunotherapy by promoting ferroptosis

Background

Although anti-programmed cell death protein 1 (PD-1) immunotherapy is greatly effective in melanoma treatment, low response rate and treatment resistance significantly hinder its efficacy. Tumor cell ferroptosis triggered by interferon (IFN)-γ that is derived from tumor-infiltrating CD8⁺ T cells greatly contributes to the effect of immunotherapy. However, the molecular mechanism underlying IFN-γ-mediated ferroptosis and related potentially promising therapeutic strategy warrant further clarification. MicroRNAs (miRNAs) participate in ferroptosis execution and can be delivered systemically by multiple carriers, which have manifested obvious therapeutic effects on cancer.

Methods

MiRNAs expression profile in IFN-γ-driven ferroptosis was obtained by RNA sequencing. Biochemical assays were used to clarify the role of miR-21-3p in IFN-γ-driven ferroptosis and the underlying mechanism. MiR-21-3p-loaded gold nanoparticles were constructed and systemically applied to analyze the role of miR-21-3p in anti-PD-1 immunotherapy in preclinical transplanted tumor model.

Results

MiRNAs expression profile of melanoma cells in IFN-γ-driven ferroptosis was first obtained. Then, upregulated miR-21-3p was proved to facilitate IFN-γ-mediated ferroptosis by potentiating lipid peroxidation. miR-21-3p increased the ferroptosis sensitivity by directly targeting thioredoxin reductase 1 (TXNRD1) to enhance lipid reactive oxygen species (ROS) generation. Furthermore, miR-21-3p overexpression in tumor synergized with anti-PD-1 antibody by promoting tumor cell ferroptosis. More importantly, miR-21-3p-loaded gold nanoparticles were constructed, and the systemic delivery of them increased the efficacy of anti-PD-1 antibody without prominent side effects in preclinical mice model. Ultimately, ATF3 was found to promote miR-21-3p transcription in IFN-γ-driven ferroptosis.

Conclusions

MiR-21–3 p upregulation contributes to IFN-γ-driven ferroptosis and synergizes with anti-PD-1 antibody. Nanoparticle delivery of miR-21–3 p is a promising therapeutic approach to increase immunotherapy efficacy without obvious systemic side effects.

Portuguese Propolis Antitumoral Activity in Melanoma Involves ROS Production and Induction of Apoptosis

Melanoma is the most aggressive and life-threatening skin cancer type. The melanoma genome is the most frequently mutated, with the BRAF mutation present in 40–60% of melanoma cases. BRAF-mutated melanomas are characterized by a higher aggressiveness and progression. Adjuvant targeted treatments, such as BRAF and MEK inhibitors, are added to surgical excision in BRAF-mutated metastatic melanomas to maximize treatment effectiveness. However, resistance remains the major therapeutic problem. Interest in natural products, like propolis, for therapeutic applications, has increased in the last years. Propolis healing proprieties offer great potential for the development of novel cancer drugs. As the activity of Portuguese propolis has never been studied in melanoma, we evaluated the antitumoral activity of propolis from Gerês (G18.EE) and its fractions (n-hexane, ethyl acetate (EtOAc), and n-butanol) in A375 and WM9 melanoma cell lines. Results from DPPH•/ABTS• radical scavenging assays indicated that the samples had relevant antioxidant activity, however, this was not confirmed in the cell models. G18.EE and its fractions decreased cell viability (SRB assay) and promoted ROS production (DHE/Mitotracker probes by flow cytometry), leading to activation of apoptotic signaling (expression of apoptosis markers). Our results suggest that the n-BuOH fraction has the potential to be explored in the pharmacological therapy of melanoma.

Disruption of Redox Homeostasis by Alterations in Nitric Oxide Synthase Activity and Tetrahydrobiopterin along with Melanoma Progression

Cutaneous melanoma emerges from the malignant transformation of melanocytes and is the most aggressive type of skin cancer. The progression can occur in different stages: radial growth phase (RGP), vertical growth phase (VGP), and metastasis. Reactive oxygen species contribute to all phases of melanomagenesis through the modulation of oncogenic signaling pathways. Tetrahydrobiopterin (BH4) is an important cofactor for NOS coupling, and an uncoupled enzyme is a source of superoxide anion (O2•-) rather than nitric oxide (NO), altering the redox homeostasis and contributing to melanoma progression. In the present work, we showed that the BH4 amount varies between different cell lines corresponding to distinct stages of melanoma progression; however, they all presented higher O2•- levels and lower NO levels compared to melanocytes. Our results showed increased NOS expression in melanoma cells, contributing to NOS uncoupling. BH4 supplementation of RGP cells, and the DAHP treatment of metastatic melanoma cells reduced cell growth. Finally, Western blot analysis indicated that both treatments act on the PI3K/AKT and MAPK pathways of these melanoma cells in different ways. Disruption of cellular redox homeostasis by the altered BH4 concentration can be explored as a therapeutic strategy according to the stage of melanoma.

MUC21 controls melanoma progression via regulating SLITRK5 and hedgehog signaling pathway

Mucins are heavily glycosylated proteins secreted by various cell types, to protect the epithelial surface of the gastrointestinal tract from damage. Currently, increasing studies provided evidence to suggest that mucins play an essential role in regulating tumor progression. However, the role of mucins and the underpinning mechanism of how mucins drive melanoma progression remains elusive. In this study, we first demonstrated that mucin 21 (MUC21) expression was significantly upregulated in metastatic melanoma tissues, and a higher MUC21 expression resulted in poor overall survival in melanoma patients by The Cancer Genome Atlas database analysis. In vitro, MUC21 overexpression markedly promoted proliferative properties and aggressive behavior of melanoma cell A375 and A875, as assessed by Cell Counting Kit-8 and transwell assay. In mechanism, we proved that MUC21 suppressed expression of SLITRK5, an integral membrane protein, leading to activation of prosurvival hedgehog pathway and sustained melanoma development. More importantly, we found that combination of hedgehog pathway inhibitor cyclopamine and chemotherapy revealed an improved anticancer effect in MUC21 overexpression xenograft model. Altogether, our study described a novel role of MUC21 in regulating tumor progression, which offers a promising target for melanoma diagnosis and therapy.

Novel Therapeutic Approaches with DNA Damage Response Inhibitors for Melanoma Treatment

Targeted therapies against components of the mitogen-activated protein kinase (MAPK) pathway and immunotherapies, which block immune checkpoints, have shown important clinical benefits in melanoma patients. However, most patients develop resistance, with consequent disease relapse. Therefore, there is a need to identify novel therapeutic approaches for patients who are resistant or do not respond to the current targeted and immune therapies. Melanoma is characterized by homologous recombination (HR) and DNA damage response (DDR) gene mutations and by high replicative stress, which increase the endogenous DNA damage, leading to the activation of DDR. In this review, we will discuss the current experimental evidence on how DDR can be exploited therapeutically in melanoma. Specifically, we will focus on PARP, ATM, CHK1, WEE1 and ATR inhibitors, for which preclinical data as single agents, taking advantage of synthetic lethal interactions, and in combination with chemo-targeted-immunotherapy, have been growing in melanoma, encouraging the ongoing clinical trials. The overviewed data are suggestive of considering DDR inhibitors as a valid therapeutic approach, which may positively impact the future of melanoma treatment.

A Cohort Study: Comorbidity and Stage Affected the Prognosis of Melanoma Patients in Taiwan

Background

Comorbidities and stages may influence the prognosis of melanoma patients in Taiwan and need to be determined.

Methods

We performed a retrospective cohort study by using the national health insurance research database in Taiwan. Patients with a primary diagnosis of melanoma by the Taiwan Cancer Registry from 2009 to 2017 were recruited as the study population. The comparison group was never diagnosed with melanoma from 2000 to 2018. The Charlson comorbidity index was conducted to calculate the subjects’ disease severity. The Cox proportional hazards model analysis was used to estimate the hazard ratio of death.

Results

We selected 476 patients, 55.5% of whom had comorbidity. A higher prevalence of comorbidity was associated with a more advanced cancer stage. The mortality rate increased with an increasing level of comorbidity in both cohorts and was higher among melanoma patients. The interaction between melanoma and comorbidity resulted in an increased mortality rate.

Conclusion

An association between poorer survival and comorbidity was verified in this study. We found that the level of comorbidity was strongly associated with mortality. A higher risk of mortality was found in patients who had localized tumors, regional metastases, or distant metastases with more comorbidity scores. Advanced stage of melanoma patients with more comorbidities was significantly associated with the higher risk of mortality rate.

Suppression of RNA editing by miR-17 inhibits the stemness of melanoma stem cells

More and more evidence suggests that microRNA (miRNA) and RNA editing play key roles in the development and progression of tumor. However, the influence of miRNA-mediated RNA editing on tumor stem cells remains unclear. In this study, the results demonstrated that miR-17, which was downregulated in melanoma stem cells, acted as a tumor inhibitor by suppressing the stemness of melanoma stem cells and promoting cell differentiation. MiR-17 targeted ADAR2 (adenosine deaminase acting on RNA 2), a gene encoding an editing enzyme required for the maintenance of melanoma stem cell stemness. In melanoma stem cells, ADAR2 was responsible for DOCK2 mRNA editing, which was able to increase the stability of DOCK2 mRNA. The in vitro and in vivo data demonstrated that DOCK2 mRNA editing upregulated the expressions of stemness and anti-apoptotic genes by activating Rac1 and then phosphorylating Akt and NF-κB, thus leading to oncogenesis of melanoma stem cells. Our findings contribute new perspectives to miRNA-regulated RNA editing in tumor progression.

Zinc-metal–organic frameworks with tunable UV diffuse-reflectance as sunscreens

Background

UV exposure continues to induce many health issues, though commercial sunscreens are available. Novel UV filters with high safety and efficacy are urgently needed. Metal–organic frameworks (MOFs) could be a suitable platform for UV filter development, due to their tunable optical, electrical, and photoelectric properties by precise controlled synthesis.

Results

Herein, four zinc-based MOFs with various bandgap energies were chose to investigate their optical behaviors and evaluate their possibility as sunscreens. Zeolitic imidazolate framework-8 (ZIF-8) was found to possess the highest and widest UV reflectance, thereby protecting against sunburn and DNA damage on mouse skin and even achieving a comparable or higher anti-UV efficacy relative to the commercially available UV filters, TiO2 or ZnO, on pig skin, a model that correlates well with human skin. Also, ZIF-8 exerted appealing characteristics for topical skin use with low radical production, low skin penetration, low toxicity, high transparency, and high stability.

Conclusion

These results confirmed ZIF-8 could potentially be a safe and effective sunscreen surrogate for human, and MOFs could be a novel source to develop more effective and safe UV filters.

Graphical Abstract

Epigenetic Modification of PD-1/PD-L1-Mediated Cancer Immunotherapy against Melanoma

Malignant melanoma is one of the representative skin cancers with unfavorable clinical behavior. Immunotherapy is currently used for the treatment, and it dramatically improves clinical outcomes in patients with advanced malignant melanoma. On the other hand, not all these patients can obtain therapeutic efficacy. To overcome this limitation of current immunotherapy, epigenetic modification is a highlighted issue for clinicians. Epigenetic modification is involved in various physiological and pathological conditions in the skin. Recent studies identified that skin cancer, especially malignant melanoma, has advantages in tumor development, indicating that epigenetic manipulation for regulation of gene expression in the tumor can be expected to result in additional therapeutic efficacy during immunotherapy. In this review, we focus on the detailed molecular mechanism of epigenetic modification in immunotherapy, especially anti-PD-1/PD-L1 antibody treatment for malignant melanoma.

ZC3H15 Correlates with a Poor Prognosis and Tumor Progression in Melanoma

Zinc figure CCCH-type containing 15 (ZC3H15), also called developmentally regulated GTP-binding protein 1 (DRG1) family regulatory protein 1 (DFRP1), is a zinc finger containing protein. Despite playing a role in cellular signaling, it is found overexpressed in acute myeloid leukemia and also an independent prognostic marker in hepatocellular carcinoma patients. However, the biological effect of ZC3H15 in malignant melanoma (MM) remains unexplored. The expression of ZC3H15 in patients was analyzed using the R2: Genomics Analysis and Visualization Platform database. Immunohistochemical analysis, western blot, and qRT-PCR were used to detect ZC3H15 expression in melanoma tissues and cell lines. MTT, BrdU, flow cytometry assay, transwell, and western blot were performed to explore the proliferation, cell cycle, invasion, and migration of melanoma cells. We undertaken colony formation assay in vitro and tumor xenograft in vivo to detect the tumorigenicity of melanoma cells. In the present study, ZC3H15 was demonstrated highly expressed in melanoma tissues and cells. Elevated ZC3H15 impairs the survival of melanoma patients. Meanwhile, attenuation of ZC3H15 in melanoma cells inhibited cell proliferation and induced cycle arrest at G0/G1 phase. Consistently, the expression of cell cycle-related proteins cyclin dependent kinase 4 (CDK4), CDK6, and cyclin D1 (CCND1) was decreased while p21 was upregulated. Furthermore, we found the migration and invasion abilities were inhibited in ZC3H15-knockdown melanoma cells. In addition, downregulation of ZC3H15 resulted in inhibition of colony formation abilities in vitro and tumorigenesis in vivo. ZC3H15 promotes proliferation, migration/invasion, and tumorigenicity of melanoma cells. As a promising biomarker and therapeutic target in MM, ZC3H15 is worthy of further exploration.

The Effects of Hedgehog Signaling Pathway on the Proliferation and Apoptosis of Melanoma Cells

BACKGROUND

Studies have found that the abnormality of the Hedgehog signaling pathway is related to the occurrence and development of a variety of tumors, but the effect of this signaling pathway on melanoma cells is still unclear.

METHODS

This study aimed to discuss the effect of Hedgehog signaling pathway on the proliferation and apoptosis of human malignant melanoma A375 cells and explore its possible mechanism in the proliferation and apoptosis of melanoma cells. Different concentrations of Hedgehog signaling pathway inhibitor cyclopamine (5, 10, 20 and 40 μM) were used to treat human melanoma A375 cells for 24, 48, and 72 h, and set a blank control group (0 μM). Trypan blue cell counting method was used to detect cell viability. MTT method was used to detect the inhibition rate of cell proliferation. Transwell was used to detect cell invasion, and flow cytometry was used to detect cell apoptosis.

RESULTS

Through the trypan blue cell counting method and MTT experiment, it was found that the Hedgehog signaling pathway inhibitor cyclopamine has an inhibitory effect on the proliferation and viability of melanoma A375 cells (P < 0.05), and the proliferation inhibitory effect is enhanced with prolonged action time in a dose- and time-dependent manner. Transwell experiment showed that compared with the blank control group, the invasion and migration ability of the treated melanoma A375 cells are significantly reduced, and the difference is statistically significant (P < 0.05). Cell apoptosis experiment showed that compared with the blank control group, the apoptosis rate of A375 cells is significantly higher after treated by 40 μM cyclopamine for 24 h, and the difference is statistically significant (P < 0.05). Gli1 and Bcl-2 protein are highly expressed in melanoma A375 cells, and their expressions show a downward trend (P < 0.05) after being treated by cyclopamine.

CONCLUSION

Cyclopamine inhibits cell proliferation and induces cell apoptosis by downregulating Gli1. Hedgehog signaling pathway can be used as a new target for the treatment of malignant melanoma, and multiple measures can be used to inhibit the signaling pathway to achieve a therapeutic effect.

Signal pathways of melanoma and targeted therapy

Melanoma is the most lethal skin cancer that originates from the malignant transformation of melanocytes. Although melanoma has long been regarded as a cancerous malignancy with few therapeutic options, increased biological understanding and unprecedented innovations in therapies targeting mutated driver genes and immune checkpoints have substantially improved the prognosis of patients. However, the low response rate and inevitable occurrence of resistance to currently available targeted therapies have posed the obstacle in the path of melanoma management to obtain further amelioration. Therefore, it is necessary to understand the mechanisms underlying melanoma pathogenesis more comprehensively, which might lead to more substantial progress in therapeutic approaches and expand clinical options for melanoma therapy. In this review, we firstly make a brief introduction to melanoma epidemiology, clinical subtypes, risk factors, and current therapies. Then, the signal pathways orchestrating melanoma pathogenesis, including genetic mutations, key transcriptional regulators, epigenetic dysregulations, metabolic reprogramming, crucial metastasis-related signals, tumor-promoting inflammatory pathways, and pro-angiogenic factors, have been systemically reviewed and discussed. Subsequently, we outline current progresses in therapies targeting mutated driver genes and immune checkpoints, as well as the mechanisms underlying the treatment resistance. Finally, the prospects and challenges in the development of melanoma therapy, especially immunotherapy and related ongoing clinical trials, are summarized and discussed.

Attenuation Effect of Radiofrequency Irradiation on UV-B-Induced Skin Pigmentation by Decreasing Melanin Synthesis and through Upregulation of Heat Shock Protein 70

Excess melanin deposition in the skin causes cosmetic problems. HSP70 upregulation decreases microphthalmia-associated transcription factor (MITF) expression, which eventually decreases tyrosinase activity and melanogenesis. Ultraviolet (UV) radiation upregulates p53, which increases the melanocortin receptor (MC1R) and MITF. Furthermore, HSP70 decreases p53 and radiofrequency irradiation (RF) increases HSP70. We evaluated whether RF increased HSP70 and decreased p53, consequently decreasing the MITF/tyrosinase pathway and melanogenesis in UV-B radiated animal skin. Various RF combinations with 50, 100, and 150 ms and 5, 10, and 15 W were performed on the UV-B radiated mouse skin every 2 d for 28 d. When RF was performed with 100 ms/10 W, melanin deposition, evaluated by Fontana–Masson staining, decreased without skin crust formation in the UV-B radiated skin. Thus, we evaluated the effect of RF on decreasing melanogenesis in the HEMn and UV-B radiated skin at a setting of 100 ms/10 W. HSP70 expression was decreased in the UV-B radiated skin but was increased by RF. The expression of p53, MC1R, and MITF increased in the UV-B radiated skin but was decreased by RF. The expression of p53, MC1R, and MITF increased in the α-MSH treated HEMn but was decreased by RF. The decreasing effects of RF on p53, MC1R, CREB and MITF were higher than those of HSP70-overexpressed HEMn. The decreasing effect of RF on p53, MC1R, CREB, and MITF disappeared in the HSP70-silenced HEMn. MC1R, CREB, and MITF were not significantly decreased by the p53 inhibitor in α-MSH treated HEMn. RF induced a greater decrease in MC1R, CREB, and MITF than the p53 inhibitor. Therefore, RF may have decreased melanin synthesis by increasing HSP70 and decreasing p53, thus decreasing MC1R/CREB/MITF and tyrosinase activity.

Silencing FYVE, RhoGEF, and PH domain containing 1 (FGD1) suppresses melanoma progression by inhibiting PI3K/AKT signaling pathway

Cutaneous melanoma is the leading cause of death among skin cancers despite the availability of diverse treatments. FGD1 plays an important role in multiple cancers, but how it works in cutaneous melanoma has not been illustrated. Thus, this study was intended to investigate the roles of FGD1 and its underlying mechanisms in cutaneous melanoma. Bioinformatics tools and quantitative real-time polymerase chain reaction (qRT-PCR) were used to analyze the expression of FGD1 in cutaneous melanoma. After the knockdown of FGD1 in melanoma cells, the proliferation, migration, and invasion of cells were analyzed by cell counting kit-8 (CCK8) assay, colony formation assays and transwell assays. Western blot was used to check the expression of key factors in PI3K/AKT pathway. In addition, nude mice models were used to study the role of FGD1 in melanoma development and metastasis in vivo. The data demonstrated that FGD1 was up-regulated and predicted a poor clinical outcome for cutaneous melanoma patients. Knockdown of FGD1 inhibited melanoma cell proliferation, migration, and invasion. The expressions of p-PI3K and p-AKT were significantly decreased, while the expressions of PI3K and AKT showed no marked difference in the knockdown group. Meanwhile, knockdown of FGD1 suppressed the development of melanoma in vivo. This study suggested that knockdown of FGD1 could block melanoma formation and proliferation by inhibiting PI3K/AKT signaling pathway. FGD1 might be a promising therapeutic target for melanoma.

Expression and Significance of AQP3 in Cutaneous Lesions

Aquaporin 3 (AQP3) is the membrane channel of water and involved in fluid homeostasis. The aim of this study was to reveal the expression and significance of AQP3 in cutaneous lesions. We analyzed AQP3 mRNA levels using RT-PCR in 311 cutaneous lesions and confirmed AQP3 expression in these lesions by immunohistochemistry. AQP3 mRNA was detected in normal epidermis, seborrheic keratosis, solar keratosis, Bowen's disease, squamous cell carcinoma, eccrine poroma, apocrine carcinoma, and sebaceoma; however, AQP3 mRNA was absent in basal cell carcinoma, nevocellular nevus, or malignant melanoma. By immunohistochemistry, diffuse AQP3 expression was seen in all keratotic lesions including seborrheic keratosis, verruca vulgaris, molluscum contagiosum, solar keratosis, Bowen's disease, and squamous cell carcinoma. Diffuse AQP3 expression was also present in all extramammary Paget's disease. No AQP3 staining was obtained in basal cell carcinoma. Positive AQP3 staining was seen in sweat gland tumors including hidradenoma, eccrine poroma, and apocrine carcinoma. Among sebaceous tumors, AQP3 expressed diffusely in all sebaceous hyperplasia and sebaceous adenoma, but not in sebaceous carcinomas. Only focal AQP3 staining was seen in nevocellular nevus and no AQP3 staining in melanoma. Our findings indicate the function of AQP3 maintained in most skin tumors. AQP3 may be used for differential diagnosis in skin tumors.

Ketoprofen Combined with UVA Irradiation Exerts Higher Selectivity in the Mode of Action against Melanotic Melanoma Cells than against Normal Human Melanocytes

Malignant melanoma is responsible for the majority of skin cancer-related deaths. The methods of cancer treatment include surgical removal, chemotherapy, immunotherapy, and targeted therapy. However, neither of these methods gives satisfactory results. Therefore, the development of new anticancer therapeutic strategies is very important and may extend the life span of people suffering from melanoma. The aim of this study was to examine the effect of ketoprofen (KTP) and UVA radiation (UVAR) therapy on cell proliferation, apoptosis, and cell cycle distribution in both melanotic melanoma cells (COLO829) and human melanocytes (HEMn-DP) in relation to its supportive effect in the treatment of melanoma. The therapy combining the use of pre-incubation with KTP and UVAR causes a significant increase in the anti-proliferative properties of ketoprofen towards melanoma cells and the co-exposure of melanotic melanoma cells induced apoptosis shown as the mitochondrial membrane breakdown, cell-cycle deregulation, and DNA fragmentation. Moreover, co-treatment led to GSH depletion showing its pro-apoptotic effect dependent on ROS overproduction. The treatment did not show a significant effect on normal cells—melanocytes—which indicates its high selectivity. The results suggest a possible benefit from the use of the ketoprofen and ultraviolet A irradiation as a new concept of melanotic melanoma therapy.

Effects of substituent position on aminobenzoate relaxation pathways in solution

The negative effects of ultraviolet radiation (UVR) on human skin have led to the widespread use of sunscreens, i.e. skincare products containing UV filters to absorb, reflect or otherwise block UVR. The mechanisms by which UV filters dissipate energy following photoexcitation, i.e. their photodynamics, can crucially determine a molecule's performance as a sunscreen UV filter. In this work, we evaluate the effects of substituent position on the in-solution relaxation pathways of two derivates of methyl anthranilate (an ortho compound that is a precursor to the UV filter meradimate), meta- and para-methyl anthranilate, m-MA and p-MA, respectively. The photodynamics of m-MA were found to be sensitive to solvent polarity: its emission spectra show larger Stokes shifts with increasing polarity, and both the fluorescence quantum yield and lifetimes for m-MA increase in polar solvents. While the Stokes shifts for p-MA are much milder and more independent of solvent environment than those of m-MA, we find its fluorescence quantum yields to be sensitive not only to solvent polarity but to the hydrogen bonding character of the solvent. In both cases (m- and p-MA) we have found common computational methods to be insufficient to appropriately model the observed spectroscopic data, likely due to an inability to account for explicit solvent interactions, a known challenge in computational chemistry. Therefore, apart from providing insight into the photodynamics of anthranilate derivatives, the work presented here also provides a case study that may be of use to theoretical chemists looking to improve and develop explicit solvent computational methods.

Difference in Sun Exposure Habits Between Individuals with High and Low Risk of Skin Cancer

Background

Skin cancer incidence is rapidly increasing. The main risk factor, sun exposure, can be modified. Informational campaigns can be effective in raising skin cancer awareness and target the high-risk population. Still, sun exposure habits in people at high risk of skin cancer are not well-known.

Objective

To investigate if and how sun exposure habits differ between low-risk and high-risk individuals.

Methods

During the Swedish Euromelanoma campaign of 2018, questionnaires were collected containing information regarding sun exposure habits and risk factors for skin cancer. Data on 4,141 participants was used to investigate the association between risk factors and sun exposure habits.

Results

A fair skin type and a previous history of skin cancer were significantly associated with enhanced sun protective behavior. Family history of skin cancer, childhood sunburns and the presence of large/atypical nevi had no effect on sun exposure habits. Going on sunny holidays were particularly unaffected by being at high risk of skin cancer.

Conclusion

Individuals at high risk of developing skin cancer showed suboptimal sun exposure habits and harmful traveling behaviors. We suggest that future skin cancer campaigns inform on accurate sun protection behavior during sunny holidays and associated risk factors. Risk factors such as childhood sunburns, numerous common and large/atypical nevi, as well as family history of skin cancer seem to be less recognized by the population.

Grape Extract Promoted α-MSH-Induced Melanogenesis in B16F10 Melanoma Cells, Which Was Inverse to Resveratrol

Melanin is a natural pigment produced by cells to prevent damage caused by ultraviolet radiation. Previously, resveratrol was shown to reduce melanin synthesis. As a natural polyphenol with various biological activities, resveratrol occurs in a variety of beverages and plant foods, such as grapes. Therefore, we investigated whether grape extracts containing resveratrol also had the ability to regulate melanin synthesis. In this study, we used mouse B16F10 melanoma cells as a model for melanin synthesis with the melanogenesis-inducing α-melanocyte-stimulating hormone (α-MSH) as a positive control. Our results confirmed previous reports that resveratrol reduces melanin synthesis by reducing the activity of the rate-limiting enzyme tyrosinase. In contrast, the grape extract could not reduce melanin synthesis, and in fact promoted melanogenesis in the presence of α-MSH. The expression of genes related to melanin synthesis, such as tyrosinase, tyrosinase-related protein-1, tyrosinase-related protein-2, and microphthalmia-associated transcription factor, also supports these phenomena, which means that even in the presence of resveratrol, grape extract will strengthen the function of α-MSH in promoting melanin synthesis. Therefore, these results also provide a point of view for research on cosmetics.

Immune Check Point Inhibitors in Primary Cutaneous T-Cell Lymphomas: Biologic Rationale, Clinical Results and Future Perspectives

Primary cutaneous T-cell lymphomas (PCTCL) are the most common types of cutaneous lymphomas, with Mycosis fungoides as the most frequent subtype. Besides early stages which usually have a good prognosis, advanced stages remain a great therapeutic challenge with low survival rates. To date, none of the currently available therapeutic options have significantly improved the outcomes of advanced cutaneous lymphomas. Recent studies have demonstrated that immune-checkpoint molecules, such as PD-1 and CTLA-4, play part in the proliferation pathways of neoplastic T-cells, as well as in other tumors. Hence, the potential role of immune-checkpoint-inhibitors in treating cutaneous lymphomas has been investigated in the last years. Herein, we outline the current knowledge regarding the role of immune-checkpoint molecules in PCTCL, their signaling pathways, microenvironment and therapeutic inhibition rationale. Moreover, we review the published data on immunotherapies in PCTCL and summarize the currently ongoing clinical trials in this field.

Metastatic Melanoma Progression Is Associated with Endothelial Nitric Oxide Synthase Uncoupling Induced by Loss of eNOS:BH4 Stoichiometry

Melanoma is the most aggressive type of skin cancer due to its high capability of developing metastasis and acquiring chemoresistance. Altered redox homeostasis induced by increased reactive oxygen species is associated with melanomagenesis through modulation of redox signaling pathways. Dysfunctional endothelial nitric oxide synthase (eNOS) produces superoxide anion (O2-•) and contributes to the establishment of a pro-oxidant environment in melanoma. Although decreased tetrahydrobiopterin (BH4) bioavailability is associated with eNOS uncoupling in endothelial and human melanoma cells, in the present work we show that eNOS uncoupling in metastatic melanoma cells expressing the genes from de novo biopterin synthesis pathway Gch1, Pts, and Spr, and high BH4 concentration and BH4:BH2 ratio. Western blot analysis showed increased expression of Nos3, altering the stoichiometry balance between eNOS and BH4, contributing to NOS uncoupling. Both treatment with L-sepiapterin and eNOS downregulation induced increased nitric oxide (NO) and decreased O2• levels, triggering NOS coupling and reducing cell growth and resistance to anoikis and dacarbazine chemotherapy. Moreover, restoration of eNOS activity impaired tumor growth in vivo. Finally, NOS3 expression was found to be increased in human metastatic melanoma samples compared with the primary site. eNOS dysfunction may be an important mechanism supporting metastatic melanoma growth and hence a potential target for therapy.

The anti-melanogenic effects of 3-O-ethyl ascorbic acid via Nrf2-mediated α-MSH inhibition in UVA-irradiated keratinocytes and autophagy induction in melanocytes

3-O-ethyl ascorbic acid (EAA) is an ether-derivative of ascorbic acid, known to inhibit tyrosinase activity, and is widely used in skincare formulations. Nevertheless, the molecular mechanisms underlying the EAA's effects are poorly understood. Here, the anti-melanogenic activity of EAA was demonstrated through Nrf2-mediated α-MSH inhibition in UVA-irradiated keratinocytes (HaCaT) and autophagy induction and inhibition of α-MSH-stimulated melanogenesis in melanocytes (B16F10). EAA pretreatment increased the HaCaT cell viability but suppressed ROS-mediated p53/POMC/α-MSH pathways in UVA-irradiated cells. Further, the conditioned medium from EAA-pretreated and UVA-irradiated HaCaT cells suppressed the MITF-CREB-tyrosinase pathways leading to the inhibition of melanin synthesis in B16F10 cells. EAA treatment increased nuclear Nrf2 translocation via the p38, PKC, and ROS pathways leading to HO-1, γ-GCLC, and NQO-1 antioxidant expression in HaCaT cells. However, Nrf2 silencing reduced the EAA-mediated anti-melanogenic activity, evidenced by impaired antioxidant gene expression and uncontrolled ROS (H₂0₂) generation following UVA irradiation. In B16F10 cells, EAA-induced autophagy was shown by enhanced LC3-II levels, AVO formation, Beclin-1 upregulation, and activation of p62/SQSTM1. Further, EAA-induced anti-melanogenic activity was substantially decreased in autophagy inhibitor (3-MA) pretreated or LC3 knockdown B16F10 cells. Notably, transmission electron microscopy data showed increased melanosome-engulfing autophagosomes in EAA-treated B16F10 cells. Moreover, EAA also down-regulated MC1R, TRP-1/-2, tyrosinase expressions, and melanin synthesis by suppressing the cAMP-CREB-mediated MITF expression in B16F10 cells stimulated with α-MSH. In vivo studies on the zebrafish model further confirmed that EAA inhibited tyrosinase expression/activity and endogenous pigmentation. In conclusion, 3-O-ethyl ascorbic acid is an effective skin-whitening agent and could be used as a topical agent for cosmetic purposes.

The Role of Glycosylation in Melanoma Progression

Malignant melanoma is the most aggressive form of skin cancer, which originates from the malignant transformation of melanocytes, the melanin-producing cells of the skin. Melanoma progression is typically described as a stepwise process in which metastasis formation ensues late during disease. A large body of evidence has shown that the accumulation of genetic and epigenetic alterations drives melanoma progression through the different steps. Mortality in melanoma is associated with metastatic disease. Accordingly, early-stage melanoma can be cured in the majority of cases by surgical excision, while late-stage melanoma is a highly lethal disease. Glycosylation is a post-translational modification that involves the transfer of glycosyl moieties to specific amino acid residues of proteins to form glycosidic bonds through the activity of glycosyltransferases. Aberrant glycosylation is considered a hallmark of cancer as it occurs in the majority of tumor types, including melanoma. The most widely occurring glycosylation changes in melanoma are represented by sialylation, fucosylation, and N- and I-glycan branching. In this review, we discuss the role of glycosylation in melanoma and provide insights on the mechanisms by which aberrant glycosylation promotes melanoma progression through activation of invasion and metastasis, immune evasion and cell proliferation.

Topical delivery of gambogic acid assisted by the combination of low-frequency ultrasound and chemical enhancers for chemotherapy of cutaneous melanoma

Anti-cutaneous melanoma activity of the skin-delivered gambogic acid (GA) has been reported in our previous study. However, it is difficult for GA to diffuse passively through intact skin without any enhancement means. In this study, a combination of chemical enhancers (EN: azone and propylene glycol) and physical ultrasound (US) was used to improve the percutaneous permeation of GA and enhance the anti-melanoma activity. The enhancement effect of the combination of EN and US (EN-US) on GA in vitro and in vivo was studied, and the enhancement mechanism and skin irritation were also evaluated. We showed that the parameters of US application at a constant frequency (30 kHz) with a duty cycle of 100% and intensity of 1.75 W/cm² for 20 min were optimal. In vitro, EN-US showed a considerable enhancement of the permeation of GA, and the enhancement effect was stronger than that with the use of EN or US alone. In vivo antitumor study showed that the tumor growth was significantly inhibited after percutaneous administration of GA by EN-US, more than in the intravenous injection group. The penetration enhancement mechanism revealed that EN-US not only altered the structure of lipid bilayers and keratins to reduce the barrier effect of the stratum corneum but also produced diffusion channels in the skin under the cavitation effect of US, thereby promoting the skin penetration of GA. In addition, there was no observable skin irritation in mice after treatment with EN-US. Our study demonstrated that the combination of EN and US improved the skin permeation and retention of GA to enhance the anti-melanoma activity. This method also provides technical guidance for the future development of topical and transdermal therapeutic system of GA.