Hypoxia-dependent drivers of melanoma progression

Deciphering oxygen distribution and hypoxia profiles in the tumor microenvironment: a data-driven mechanistic modeling approach

Objective. The distribution of hypoxia within tissues plays a critical role in tumor diagnosis and prognosis. Recognizing the significance of tumor oxygenation and hypoxia gradients, we introduce mathematical frameworks grounded in mechanistic modeling approaches for their quantitative assessment within a tumor microenvironment. By utilizing known blood vasculature, we aim to predict hypoxia levels across different tumor types.Approach. Our approach offers a computational method to measure and predict hypoxia using known blood vasculature. By formulating a reaction-diffusion model for oxygen distribution, we derive the corresponding hypoxia profile.Main results. The framework successfully replicates observed inter- and intra-tumor heterogeneity in experimentally obtained hypoxia profiles across various tumor types (breast, ovarian, pancreatic). Additionally, we propose a data-driven method to deduce partial differential equation models with spatially dependent parameters, which allows us to comprehend the variability of hypoxia profiles within tissues. The versatility of our framework lies in capturing diverse and dynamic behaviors of tumor oxygenation, as well as categorizing states of vascularization based on the dynamics of oxygen molecules, as identified by the model parameters.Significance. The proposed data-informed mechanistic method quantitatively assesses hypoxia in the tumor microenvironment by integrating diverse histopathological data and making predictions across different types of data. The framework provides valuable insights from both modeling and biological perspectives, advancing our comprehension of spatio-temporal dynamics of tumor oxygenation.

Rodent models of dermatological disorders

To assess the possible beneficial effects of drugs and drug candidates, different dermatological disease models are available in rodents. These models are able to mimic one or more characteristic features of the disorders, but not completely recapitulate the pathogenesis of the human skin diseases. Therefore, to improve the technology many new models have been developed both by genetic engineering and by chemical or physical induction. Currently the in vivo rodent models provide the physiologically most relevant approach to produce the pathology related to the majority of dermatological diseases. In this short review some widely used animal techniques (psoriasis, allergic contact dermatitis, atopic dermatitis, wound healing, melanoma and non-melanoma type skin cancers and UV erythema) are shown which are currently applied in pharmacological, pharmacokinetic, pharmaceutical and dermatological research. First the main points of the human pathomechanism are shown and afterwards the rodent models are briefly discussed. Finally critical evaluation is provided by the authors. However, according to the 3R rule the number of experimental animals is strongly suggested to be reduced, therefore the advanced in vitro and ex vivo techniques become more and more important contrary to in vivo preclinical methods also in dermatological research. As it is described in the outlook section, although the 2D/3D in vitro and skin on-a-chip techniques are promising and have many advantages they are not able to completely substitute the animal models in their vascular, immunological, secretory and neural complexity.

Notch signaling pathway in cancer: from mechanistic insights to targeted therapies

Notch signaling, renowned for its role in regulating cell fate, organ development, and tissue homeostasis across metazoans, is highly conserved throughout evolution. The Notch receptor and its ligands are transmembrane proteins containing epidermal growth factor-like repeat sequences, typically necessitating receptor-ligand interaction to initiate classical Notch signaling transduction. Accumulating evidence indicates that the Notch signaling pathway serves as both an oncogenic factor and a tumor suppressor in various cancer types. Dysregulation of this pathway promotes epithelial-mesenchymal transition and angiogenesis in malignancies, closely linked to cancer proliferation, invasion, and metastasis. Furthermore, the Notch signaling pathway contributes to maintaining stem-like properties in cancer cells, thereby enhancing cancer invasiveness. The regulatory role of the Notch signaling pathway in cancer metabolic reprogramming and the tumor microenvironment suggests its pivotal involvement in balancing oncogenic and tumor suppressive effects. Moreover, the Notch signaling pathway is implicated in conferring chemoresistance to tumor cells. Therefore, a comprehensive understanding of these biological processes is crucial for developing innovative therapeutic strategies targeting Notch signaling. This review focuses on the research progress of the Notch signaling pathway in cancers, providing in-depth insights into the potential mechanisms of Notch signaling regulation in the occurrence and progression of cancer. Additionally, the review summarizes pharmaceutical clinical trials targeting Notch signaling for cancer therapy, aiming to offer new insights into therapeutic strategies for human malignancies.

Targeting HIF-1α with Specific DNA Yokes for Effective Anticancer Therapy

Hypoxia, a ubiquitous hallmark in cancer, underscores the significance of targeting HIF-1α, the principal transcriptional factor of hypoxic responses, for effective cancer therapy. Herein, DNA yokes, a novel class of DNA nanomaterials harboring specific HIF-1α binding sequences (hypoxia response elements, HREs), are introduced as nanopharmaceuticals for cancer treatment. Comprising a basal tetrahedral DNA nanostructure and four HRE-bearing overhanging chains, DNA yokes exhibit exceptional stability and prolonged intracellular retention. The investigation reveals their capacity to bind HIF-1α, thereby disrupting its interaction with the downstream genomic DNAs and impeding transcriptional activity. Moreover, DNA yokes facilitate HIF-1α degradation via the ubiquitination pathway, thereby sequestering it from downstream targets and ultimately promoting its degradation. In addition, DNA yokes attenuate cancer cell proliferation, migration, and invasion under hypoxic conditions, while also displaying preferential accumulation within tumors, thereby inhibiting tumor growth and metastasis in vivo. This study pioneers a novel approach to cancer therapy through the development of DNA-based drugs characterized by high stability and low toxicity to normal cells, positioning DNA yokes as promising candidates for cancer treatment.

A signature of seven hypoxia-related lncRNAs is a potential biomarker for predicting the prognosis of melanoma

Melanoma is the most aggressive type of skin cancer and has a high mortality rate once metastasis occurs. Hypoxia is a universal characteristic of the microenvironment of cancer and a driver of melanoma progression. In recent years, long noncoding RNAs (lncRNAs) have attracted widespread attention in oncology research. In this study, screening was performed and revealed seven hypoxia-related lncRNAs AC008687.3, AC009495.1, AC245128.3, AL512363.1, LINC00518, LINC02416 and MCCC1-AS1 as predictive biomarkers. A predictive risk model was constructed via univariate Cox regression analysis, least absolute shrinkage and selection operator (LASSO), and multivariate Cox regression analyses. Patients were grouped according to the model risk score, and Kaplan-Meier analysis was performed to compare survival between groups. Functional and pathway enrichment analyses were performed to compare gene set enrichment between groups. Moreover, a nomogram was constructed with the risk score as a variable. In both the training and validation sets, patients in the low-risk group had better overall survival than did those in the high-risk group (P<0.001). The 3-, 5- and 10-year area under the curve (AUC) values for the nomogram model were 0.821, 0.795 and 0.820, respectively. Analyses of immune checkpoints, immunotherapy response, drug sensitivity, and mutation landscape were also performed. The results suggested that the low-risk group had a better response to immunotherapeutic. In addition, the nomogram can effectively predict the prognosis and immunotherapy response of melanoma patients. The signature of seven hypoxia-related lncRNAs showed great potential value as an immunotherapy response biomarker, and these lncRNAs might be treatment targets for melanoma patients.

Hypoxia-associated markers in the prognosis of oral canine melanoma

Canine oral malignant melanoma (COMM) is the most common neoplasm in the oral cavity characterized by local invasiveness and high metastatic potential. Hypoxia represents a crucial feature of the solid tumor microenvironment promoting cancer progression and drug resistance. Hypoxia-inducible factor-1α (HIF-1α) and its downstream effectors, vascular endothelial growth factor A (VEGF-A), glucose transporter isoform 1 (GLUT1), C-X-C chemokine receptor type 4 (CXCR4), and carbonic anhydrase IX (CAIX), are the main regulators of the adaptive response to low oxygen availability. The prognostic value of these markers was evaluated in 36 COMMs using immunohistochemistry. In addition, the effects of cobalt chloride-mediated hypoxia were evaluated in 1 primary COMM cell line. HIF-1α expression was observed in the nucleus, and this localization correlated with the presence or enhanced expression of HIF-1α-regulated genes at the protein level. Multivariate analysis revealed that in dogs given chondroitin sulfate proteoglycan-4 (CSPG4) DNA vaccine, COMMs expressing HIF-1α, VEGF-A, and CXCR4 were associated with shorter disease-free intervals (DFI) compared with tumors that were negative for these markers (P = .03), suggesting hypoxia can influence immunotherapy response. Western blotting showed that, under chemically induced hypoxia, COMM cells accumulate HIF-1α and smaller amounts of CAIX. HIF-1α induction and stabilization triggered by hypoxia was corroborated by immunofluorescence, showing its nuclear translocation. These findings reinforce the role of an hypoxic microenvironment in tumor progression and patient outcome in COMM, as previously established in several human and canine cancers. In addition, hypoxic markers may represent promising prognostic markers, highlighting opportunities for their use in therapeutic strategies for COMMs.

AIBI Modified Mesoporous Copper Sulfide Nanocomposites for Efficient Non-Oxygen Dependent Free Radicals-Assisted Photothermal Therapy in Uveal Melanoma

Uveal melanoma (UM) is an ocular cancer predominantly affecting adults, characterized by challenging diagnostic outcomes. This research endeavors to develop an innovative multifunctional nanocomposite system sensitive to near-infrared (NIR) radiation, serving as both a non-oxygen free-radical generator and a photothermal agent. The designed system combines azobis isobutyl imidazoline hydrochloride (AIBI) with mesoporous copper sulfide (MCuS) nanoparticles. MCuS harnesses NIR laser energy to induce photothermal therapy, converting light energy into heat to destroy cancer cells. Simultaneously, AIBI is activated by the NIR laser to produce alkyl radicals, which induce DNA damage in remaining cancer cells. This distinctive feature equips the designed system to selectively eliminate cancers in the hypoxic tumor microenvironment. MCuS is also beneficial to scavenge the overexpressed glutathione (GSH) in the tumor microenvironment. GSH generally consumes free radicals and hiders the PDT effect. To enhance control over AIBI release in cancer cells, 1-tetradecyl alcohol (TD), a phase-changing material, is introduced onto the surface of MCuS nanoparticles to create the final AMPT nanoparticle system. In vitro and in vivo experiments confirm the remarkable anti-tumor efficacy of AMPT. Notably, the study introduces an orthotopic tumor model for UM, demonstrating the feasibility of precise and effective targeted treatment within the ocular system.

Melanomas and mast cells: an ambiguous relationship

Mast cells (MCs) accumulate in a broad range of tumors, including melanomas. While MCs are potent initiators of immunity in infection, and in allergic inflammation, the function of MCs in anti-melanoma immunity is unclear. MCs have the potential to release tumoricidal cytokines and proteases, to activate antigen-presenting cells and to promote anti-tumor adaptive immunity. However, within the immunosuppressive tumor microenvironment (TME), MC activation may promote angiogenesis and contribute to tumor growth. In this review, the relationship between MCs and melanomas is discussed with a focus on the impact of the TME on MC activation.

Incorporating network diffusion and peak location information for better single-cell ATAC-seq data analysis

Single-cell assay for transposase-accessible chromatin using sequencing (scATAC-seq) data provided new insights into the understanding of epigenetic heterogeneity and transcriptional regulation. With the increasing abundance of dataset resources, there is an urgent need to extract more useful information through high-quality data analysis methods specifically designed for scATAC-seq. However, analyzing scATAC-seq data poses challenges due to its near binarization, high sparsity and ultra-high dimensionality properties. Here, we proposed a novel network diffusion-based computational method to comprehensively analyze scATAC-seq data, named Single-Cell ATAC-seq Analysis via Network Refinement with Peaks Location Information (SCARP). SCARP formulates the Network Refinement diffusion method under the graph theory framework to aggregate information from different network orders, effectively compensating for missing signals in the scATAC-seq data. By incorporating distance information between adjacent peaks on the genome, SCARP also contributes to depicting the co-accessibility of peaks. These two innovations empower SCARP to obtain lower-dimensional representations for both cells and peaks more effectively. We have demonstrated through sufficient experiments that SCARP facilitated superior analyses of scATAC-seq data. Specifically, SCARP exhibited outstanding cell clustering performance, enabling better elucidation of cell heterogeneity and the discovery of new biologically significant cell subpopulations. Additionally, SCARP was also instrumental in portraying co-accessibility relationships of accessible regions and providing new insight into transcriptional regulation. Consequently, SCARP identified genes that were involved in key Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways related to diseases and predicted reliable cis-regulatory interactions. To sum up, our studies suggested that SCARP is a promising tool to comprehensively analyze the scATAC-seq data.

A Review of Genes Involved in Wound Healing

Background

Gene therapy holds immense potential in the field of wound healing. However, we still do not recognize this procedure well enough to give oversight effectively to improve healing processes. A wide range of information has been achieved from the database for gene expression profiling by clinical trials, So we performed this study to gain a better understanding of the mechanisms behind wound healing and how it could be utilized to develop new therapies and treatments.

Methods

In this study, we have been focusing on wound-healing genes, conducting a thorough review to explore the various genes and pathways involved in this process. For this purpose, a total of 320 articles were collected. All experimental studies, systematic or narrative reviews, studies and clinical trials included in this paper were searched on PubMed, Medline, Embase, Science Direct, and Scopus databases in English using the following terms: Wound Healing, wound regeneration, Gene Transfer, and Gene Therapy were used to search the mentioned databases. Unfortunately, we didn't find a large sample cohort study on this topic. A total amount of 330 articles were collected based on the guidelines of the PRISMA method. Both inclusion and exclusion criteria were settled.

Results

During the last decade, different models of gene delivery have been introduced, which include viral transfection and Non-viral techniques. In this regard, TIMP-2 protein and VEGF mutants such as VEGF165, CARP, and HIF-1 are the genes that accelerate the rate of tissue repair.

Conclusion

The process of wound healing is mainly related to the change of expression of genes that have a role in the parts of inflammation and repair. In our study, some of the most suitable genes involved in the wound-healing process are mentioned.

The nexus of natural killer cells and melanoma tumor microenvironment: crosstalk, chemotherapeutic potential, and innovative NK cell-based therapeutic strategies

The metastasis of melanoma cells to regional lymph nodes and distant sites is an important contributor to cancer-related morbidity and mortality among patients with melanoma. This intricate process entails dynamic interactions involving tumor cells, cellular constituents, and non-cellular elements within the microenvironment. Moreover, both microenvironmental and systemic factors regulate the metastatic progression. Central to immunosurveillance for tumor cells are natural killer (NK) cells, prominent effectors of the innate immune system with potent antitumor and antimetastatic capabilities. Recognizing their pivotal role, contemporary immunotherapeutic strategies are actively integrating NK cells to combat metastatic tumors. Thus, a meticulous exploration of the interplay between metastatic melanoma and NK cells along the metastatic cascade is important. Given the critical involvement of NK cells within the melanoma tumor microenvironment, this comprehensive review illuminates the intricate relationship between components of the melanoma tumor microenvironment and NK cells, delineating their multifaceted roles. By shedding light on these critical aspects, this review advocates for a deeper understanding of NK cell dynamics within the melanoma context, driving forward transformative strategies to combat this cancer.

CAR NK Cell Therapy for the Treatment of Metastatic Melanoma: Potential & Prospects

Melanoma is among the most lethal forms of cancer, accounting for 80% of deaths despite comprising just 5% of skin cancer cases. Treatment options remain limited due to the genetic and epigenetic mechanisms associated with melanoma heterogeneity that underlie the rapid development of secondary drug resistance. For this reason, the development of novel treatments remains paramount to the improvement of patient outcomes. Although the advent of chimeric antigen receptor-expressing T (CAR-T) cell immunotherapies has led to many clinical successes for hematological malignancies, these treatments are limited in their utility by their immune-induced side effects and a high risk of systemic toxicities. CAR natural killer (CAR-NK) cell immunotherapies are a particularly promising alternative to CAR-T cell immunotherapies, as they offer a more favorable safety profile and have the capacity for fine-tuned cytotoxic activity. In this review, the discussion of the prospects and potential of CAR-NK cell immunotherapies touches upon the clinical contexts of melanoma, the immunobiology of NK cells, the immunosuppressive barriers preventing endogenous immune cells from eliminating tumors, and the structure and design of chimeric antigen receptors, then finishes with a series of proposed design innovations that could improve the efficacy CAR-NK cell immunotherapies in future studies.

Dihydroartemisinin inhibits melanoma migration and metastasis by affecting angiogenesis

Tumor angiogenesis is critical for tumor metastasis by providing oxygen, nutrients, and metastatic pathways. As a potential anti-angiogenic agent, Dihydroartemisinin (DHA) can effectively inhibit tumor metastasis. However, the mechanism how it regulates angiogenesis to affect tumor metastasis has not been fully clarified. To investigate the mechanisms of how DHA regulates melanoma progression. In this study, bioinformatics methods were used to analyze the correlation between angiogenesis and melanoma metastasis. Then, B16F10, A375, HUVECs and mouse metastasis models were adapted to clarify the inhibition of DHA in melanoma. GESA analysis revealed melanoma metastasis significantly positive correlated with angiogenesis. Meanwhile, DHA significantly decreased melanoma nodules and lung wet weight in metastatic tumor mice, and inhibited the expression of the angiogenic marker CD31 in vitro and in vivo. Similarly, DHA inhibited the expression of the angiogenic signal molecule VEGFR2 in A375 and B16F10 cells, and significantly suppressed the formation of their tubular structures. DHA-treated supernatants significantly inhibited the tubule-forming ability as well as lateral and longitudinal migration ability of HUVECs compared with untreated melanoma cell supernatants. Screening yielded the angiogenic pathways HIF-1α/VEGF, PI3K/ATK/mTOR associated with melanoma metastasis, and DHA may inhibit tumor metastasis by inhibiting these angiogenic pathways in melanoma cells to inhibit tumor metastasis. Further non-targeted metabolomics analysis revealed that DHA-treated model mice produced differential metabolites that were also associated with angiogenic pathways. DHA inhibits melanoma invasion and metastasis by mediating angiogenesis. These results have important implications for the potential use of DHA in treatment of melanoma.

On the treatment of melanoma: A mathematical model of oncolytic virotherapy

We develop and analyze a mathematical model of oncolytic virotherapy in the treatment of melanoma. We begin with a special, local case of the model, in which we consider the dynamics of the tumour cells in the presence of an oncolytic virus at the primary tumour site. We then consider the more general regional model, in which we incorporate a linear network of lymph nodes through which the tumour cells and the oncolytic virus may spread. The modelling also considers the impact of hypoxia on the disease dynamics. The modelling takes into account both the effects of hypoxia on tumour growth and spreading, as well as the impact of hypoxia on oncolytic virotherapy as a treatment modality. We find that oxygen-rich environments are favourable for the use of adenoviruses as oncolytic agents, potentially suggesting the use of complementary external oxygenation as a key aspect of treatment. Furthermore, the delicate balance between a virus' infection capabilities and its oncolytic capabilities should be considered when engineering an oncolytic virus. If the virus is too potent at killing tumour cells while not being sufficiently effective at infecting them, the infected tumour cells are destroyed faster than they are able to infect additional tumour cells, leading less favourable clinical results. Numerical simulations are performed in order to support the analytic results and to further investigate the impact of various parameters on the outcomes of treatment. Our modelling provides further evidence indicating the importance of three key factors in treatment outcomes: tumour microenvironment oxygen concentration, viral infection rates, and viral oncolysis rates. The numerical results also provide some estimates on these key model parameters which may be useful in the engineering of oncolytic adenoviruses.

In Vitro Experiments on the Effects of GP-2250 on BRAF-Mutated Melanoma Cell Lines and Benign Melanocytes

Enhanced glycolysis (Warburg effect) driven by the BRAF oncogene, dysregulated GAPDH expression, and activation of the PI3K/AKT/mTOR signaling pathway may significantly contribute to the resistance-targeted therapy of BRAF-mutated melanomas. Therefore, we aimed to study for the first time the anti-tumor activity of the GAPDH inhibitor GP-2250 in BRAF-mutated melanoma cell lines and benign melanocytes. We employed three melanoma cell lines and one primary melanocyte cell line (Ma-Mel-61a, Ma-Mel-86a, SH-4 and ATCC-PCS-200-013, respectively), which were exposed to different GP-2250 doses. GP-2250's effects on cell proliferation and viability were evaluated by means of the BrdU and MTT assays, respectively. The RealTime-Glo Annexin V Apoptosis and Necrosis Assay was performed for the evaluation of apoptosis and necrosis induction. RT-PCR and western blotting were implemented for the determination of AKT and STAT3 gene and protein expression analyses, respectively. The melanoma cell lines showed a dose-dependent response to GP-2250 during BrDU and MTT testing. The RealTime-Glo Annexin V assay revealed the heterogenous impact of GP-2250 on apoptosis as well as necrosis. With respect to the melanoma cell lines Ma-Mel-86a and SH-4, the responses and dosages were comparable to those used for the MTT viability assay. Using the same dose range of GP-2250 administered to melanoma cells, however, we observed neither the noteworthy apoptosis nor necrosis of GP-2250-treated benign melanocytes. The gene expression profiles in the melanoma cell lines for AKT and STAT3 were heterogenous, whereby AKT as well as STAT3 gene expression were most effectively downregulated using the highest GP-2250 doses. Immunoblotting revealed that there was a time-dependent decrease in protein expression at the highest GP-2250 dose used, whereas a time- as well as dose-dependent AKT decrease was predominantly observed in Ma-Mel-61a. The STAT3 protein expression of Ma-Mel-86a and SH-4 was reduced in a time-dependent pattern at lower and moderate doses. STAT3 expression in Ma-Me-61a was barely altered by GP-2250. In conclusion, GP-2250 has anti-neoplastic effects in BRAF-mutated melanoma cell lines regarding tumor cell viability, proliferation, and apoptosis/necrosis. GP-2250 is able to downregulate the gene and protein expression of aberrant tumorigenic pathways in melanoma cell lines. Since GP-2250 is a GAPDH inhibitor, the substance may be a promising combination therapy for tumors presenting the Warburg effect, such as melanoma.

Self-adaptive nanoassembly enabling turn-on hypoxia illumination and periphery/center closed-loop tumor eradication

Solid tumors are regarded as complex evolving systems rather than simple diseases. Self-adaptive synthetic therapeutics are required to cope with the challenges of entire tumors; however, limitations in accurate positioning and destruction of hypoxic niches seriously hinder complete tumor eradication. In this study, we engineer a molecular nanoassembly of sorafenib and a hypoxia-sensitive cyanine probe (CNO) to facilitate periphery/center synergistic cancer therapies. The self-adaptive nanoassembly with cascade drug release features not only effectively kills the peripheral tumor cells in normoxic rims but precisely illuminates hypoxic niches following the reduction of CNO by nitroreductase. More important, CNO is found to synergistically induce tumor ferroptosis with sorafenib via nicotinamide adenine dinucleotide phosphate (NADPH) depletion in hypoxic niches. As expected, the engineered nanoassembly demonstrates self-adaptive hypoxic illumination and periphery/center synergetic tumor eradication in colon and breast cancer BALB/c mouse xenograft models. This study advances turn-on hypoxia illumination and chemo-ferroptosis toward clinical applicability.

CA-IX-Expressing Small Extracellular Vesicles (sEVs) Are Released by Melanoma Cells under Hypoxia and in the Blood of Advanced Melanoma Patients

Cutaneous melanoma is a highly aggressive skin cancer, with poor prognosis. The tumor microenvironment is characterized by areas of hypoxia. Carbonic anhydrase IX (CA-IX) is a marker of tumor hypoxia and its expression is regulated by hypoxia-inducible factor-1 (HIF-1). CA-IX has been found to be highly expressed in invasive melanomas. In this study, we investigated the effects of hypoxia on the release of small extracellular vesicles (sEVs) in two melanoma in vitro models. We demonstrated that melanoma cells release sEVs under both normoxic and hypoxic conditions, but only hypoxia-induced sEVs express CA-IX mRNA and protein. Moreover, we optimized an ELISA assay to provide evidence for CA-IX protein expression on the membranes of the sEVs. These CA-IX-positive sEVs may be exploited as potential biomarkers for liquid biopsy.

Hypoxia in Skin Cancer: Molecular Basis and Clinical Implications

Skin cancer is one of the most prevalent cancers in the Caucasian population. In the United States, it is estimated that at least one in five people will develop skin cancer in their lifetime, leading to significant morbidity and a healthcare burden. Skin cancer mainly arises from cells in the epidermal layer of the skin, where oxygen is scarce. There are three main types of skin cancer: malignant melanoma, basal cell carcinoma, and squamous cell carcinoma. Accumulating evidence has revealed a critical role for hypoxia in the development and progression of these dermatologic malignancies. In this review, we discuss the role of hypoxia in treating and reconstructing skin cancers. We will summarize the molecular basis of hypoxia signaling pathways in relation to the major genetic variations of skin cancer.

Ethanol Metabolism and Melanoma

Malignant melanoma is the deadliest form of skin cancer. Despite significant efforts in sun protection education, melanoma incidence is still rising globally, drawing attention to other socioenvironmental risk factors for melanoma. Ethanol and acetaldehyde (AcAH) are ubiquitous in our diets, medicines, alcoholic beverages, and the environment. In the liver, ethanol is primarily oxidized to AcAH, a toxic intermediate capable of inducing tumors by forming adducts with proteins and DNA. Once in the blood, ethanol and AcAH can reach the skin. Although, like the liver, the skin has metabolic mechanisms to detoxify ethanol and AcAH, the risk of ethanol/AcAH-associated skin diseases increases when the metabolic enzymes become dysfunctional in the skin. This review highlights the evidence linking cutaneous ethanol metabolism and melanoma. We summarize various sources of skin ethanol and AcAH and describe how the reduced activity of each alcohol metabolizing enzyme affects the sensitivity threshold to ethanol/AcAH toxicity. Data from the Gene Expression Omnibus database also show that three ethanol metabolizing enzymes (alcohol dehydrogenase 1B, P450 2E1, and catalase) and an AcAH metabolizing enzyme (aldehyde dehydrogenase 2) are significantly reduced in melanoma tissues.

Phytochemicals as Immunomodulatory Agents in Melanoma

Cutaneous melanoma is an immunogenic highly heterogenic tumor characterized by poor outcomes when it is diagnosed late. Therefore, immunotherapy in combination with other anti-proliferative approaches is among the most effective weapons to control its growth and metastatic dissemination. Recently, a large amount of published reports indicate the interest of researchers and clinicians about plant secondary metabolites as potentially useful therapeutic tools due to their lower presence of side effects coupled with their high potency and efficacy. Published evidence was reported in most cases through in vitro studies but also, with a growing body of evidence, through in vivo investigations. Our aim was, therefore, to review the published studies focused on the most interesting phytochemicals whose immunomodulatory activities and/or mechanisms of actions were demonstrated and applied to melanoma models.

Metabolism heterogeneity in melanoma fuels deactivation of immunotherapy: Predict before protect

Malignant melanoma is widely acknowledged as the most lethal skin malignancy. The metabolic reprogramming in melanoma leads to alterations in glycolysis and oxidative phosphorylation (OXPHOS), forming a hypoxic, glucose-deficient and acidic tumor microenvironment which inhibits the function of immune cells, resulting in a low response rate to immunotherapy. Therefore, improving the tumor microenvironment by regulating the metabolism can be used to improve the efficacy of immunotherapy. However, the tumor microenvironment (TME) and the metabolism of malignant melanoma are highly heterogeneous. Therefore, understanding and predicting how melanoma regulates metabolism is important to improve the local immune microenvironment of the tumor, and metabolism regulators are expected to increase treatment efficacy in combination with immunotherapy. This article reviews the energy metabolism in melanoma and its regulation and prediction, the integration of immunotherapy and metabolism regulators, and provides a comprehensive overview of future research focal points in this field and their potential application in clinical treatment.

Tissue Biomarkers Predicting Lymph Node Status in Cutaneous Melanoma

Cutaneous melanoma is a severe neoplasm that shows early invasiveness of the lymph nodes draining the primary site, with increased risk of distant metastases and recurrence. The tissue biomarker identification could be a new frontier to predict the risk of early lymph node invasiveness, especially in cases considered by current guidelines to be at low risk of lymph node involvement and not requiring evaluation of the sentinel lymph node (SLN). For this reason, we present a narrative review of the literature, seeking to provide an overview of current tissue biomarkers, particularly vascular endothelium growth factors (VEGF), Tetraspanin CD9, lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1), D2-40, and gene expression profile test (31-GEP). Among these, 31-GEP seems to be able to provide a distinction between low or high risk for positive SLN classes. VEGF receptor-3 and CD9 expression may be independent predictors of positive SLN. Lastly, LYVE-1 and D2-40 allow an easier assessment of lymph vascular invasion, which can be considered a good predictor of SLN status. In conclusion, biomarkers to assess the lymph node status of cutaneous melanoma patients may play an important role in those cases where the clinician is in doubt whether or not to perform SLN biopsy.

Hypoxia-Nitric Oxide Axis and the Associated Damage Molecular Pattern in Cutaneous Melanoma

Hypoxia was intensively studied in cancer during the last few decades, being considered a characteristic of the tumor microenvironment. The aim of the study was to evaluate the capacity of tumor cells to adapt to the stress generated by limited oxygen tissue in cutaneous melanoma. We developed a case-control prospective study that included 52 patients with cutaneous melanoma and 35 healthy subjects. We focused on identifying and monitoring hypoxia, the dynamic of nitric oxide (NO) serum metabolites and posttranslational metabolic disorders induced by NO signaling according to the clinical, biological and tumoral characteristics of the melanoma patients. Our study showed high levels of hypoxia-inducible factor-1a (HIF-1a) and hypoxia-inducible factor-2a (HIF-2a) in the melanoma patients. Hypoxia-inducible factors (HIFs) control the capacity of tumor cells to adapt to low levels of oxygen. Hypoxia regulated the nitric oxide synthase (NOS) expression and activity. In the cutaneous melanoma patients, disorders in NO metabolism were detected. The serum levels of the NO metabolites were significantly higher in the melanoma patients. NO signaling influenced the tumor microenvironment by modulating tumoral proliferation and sustaining immune suppression. Maintaining NO homeostasis in the hypoxic tumoral microenvironment could be considered a future therapeutic target in cutaneous melanoma.

The construction of a hypoxia-based signature identified CA12 as a risk gene affecting uveal melanoma cell malignant phenotypes and immune checkpoint expression

Uveal melanoma (UM) is a deadly intraocular neoplasm in the adult population and harbors limited therapeutic effects from the current treatment. Here, we aimed to investigate the role of hypoxia in UM progress. We adopted the Cancer Genome Atlas data set as a training cohort and Gene Expression Omnibus data sets as validating cohorts. We first used consensus clustering to identify hypoxia-related subtypes, and the C1 subtype predicted an unfavorable prognosis and exhibited high infiltration of immunocytes and globally elevated immune checkpoint expression. Besides this, the patients with the C1 subtype were predicted to respond to the PD-1 treatment. By the least absolute shrinkage and selection operator algorithm, we constructed a hypoxia risk score based on the hypoxia genes and identified 10 genes. The risk score predicted patient survival with high performance, and the high-risk group also harbored high immunocyte infiltration and immune checkpoint expression. Furthermore, we confirmed that the risk genes were upregulated under hypoxia, and knockdown of CA12 inhibited the epithelial–mesenchymal transition process, clone formation ability, and G1/S phase transformation of the UM cells. The CD276 was also downregulated when CA12 knockdown was performed. These results validate the prognostic role of the hypoxia signature in UM and demonstrate that CA12 is a critical factor for UM cell progression as well as a target to improve immunotherapeutic effects. We believe our study contributes to the understanding of hypoxia’s roles in UM and provides a novel target that will benefit future therapeutic strategy development.

Hypoxia and Ezrin Expression in Primary Melanoma Have High Prognostic Relevance

Hypoxia affects tumor aggressiveness and activates pathways associated with epithelial mesenchymal transition (EMT) which are crucial for tumor progress. In this study, the correlation of hypoxia and EMT with sentinel lymph node status and tumor-specific survival was investigated in primary melanomas. CD34 for capillary count and Hypoxia inducible factor-1α (HIF-1α) as hypoxia indicators as well as Ezrin and L1-Cell Adhesion Molecule (L1CAM), both critical proteins contributing to EMT, were analyzed using immunohistochemistry in 49 melanoma patients with long follow-up (F/U, mean 110 months; range 12−263 months). We found a significant correlation between Breslow tumor thickness and Ezrin expression (p = 0.018). L1CAM expression in primary melanoma was significantly associated with HIF-1α expression (p < 0.0001) and sentinel lymph node metastasis (p = 0.011). Furthermore, low capillary count, reflecting hypoxic condition, was significantly associated with Ezrin expression (p = 0.047) and decreased tumor-specific survival (p = 0.035). In addition, patients with high Ezrin expression in their primary melanoma had a dramatic loss of life early in their F/U period (mean survival time 29 months; range 15−44 month). Our results highlight the relevance of Ezrin, L1CAM and HIF-1α as prognostic markers in melanoma patients. Additionally, we demonstrate that hypoxia in primary melanoma affects EMT and is at least partly responsible for early metastatic dissemination.

Construction and verification of a hypoxia-related nine-gene prognostic model in uveal melanoma based on integrated single-cell and bulk RNA sequencing analyses

Uveal melanoma (UM) is the most common primary intraocular tumor with high metastasis and poor prognosis among adults. Hypoxia participates in the metastasis process in various types of cancers. It is reported that the increased expression of hypoxia inducible factor 1 alpha subunit (HIF1A), a hypoxia-related molecule, is associated with worse prognoses of UM patients. Based on the integrated analysis of single-cell sequencing (scRNA-seq) dataset from Gene Expression Omnibus (GEO) and bulk RNA-seq dataset from the Cancer Genome Atlas (TCGA), we found hypoxia was the key feature in UM progression and identified 47 common hypoxia-related differentially expressed genes (DEGs) for the following research. Univariate cox analysis and LASSO-Cox regression analysis were performed to establish a nine-gene prognostic model. According to this model, UM patients could be divided into high- and low-risk groups, with a significant difference in overall survival and progression free survival between the two groups (P < 0.001). The accuracy of the predictive model was also verified on two other independent datasets. In addition, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses revealed that these hypoxia-related DEGs were enriched in immune and cancer related pathways. The proportion of immune infiltration and the expression of immune biomarkers were different between high- and low-risk UM patients, providing potential targets for UM immunotherapy. Hence, our hypoxia-related nine-gene model could efficiently predict the prognosis and guide personalized therapies for UM patients.

Hypoxia-responsive circRNAs: A novel but important participant in non-coding RNAs ushered toward tumor hypoxia

Given the rapid developments in RNA-seq technologies and bioinformatic analyses, circular RNAs (circRNAs) have gradually become recognized as a novel class of endogenous RNAs, characterized by covalent loop structures lacking free terminals, which perform multiple biological functions in cancer genesis, progression and metastasis. Hypoxia, a common feature of the tumor microenvironments, profoundly affects several fundamental adaptive responses of tumor cells by regulating the coding and non-coding transcriptomes and renders cancer's phenotypes more aggressive. Recently, hypoxia-responsive circRNAs have been recognized as a novel player in hypoxia-induced non-coding RNA transcriptomics to modulate the hypoxic responses and promote the progression and metastasis of hypoxic tumors. Moreover, via extracellular vesicles-exosomes, these hypoxia-responsive circRNAs could transmit hypoxia responses from cancer cells to the cells of surrounding matrices, even more distant cells of other organs. Here, we have summarized what is known about hypoxia-responsive circRNAs, with a focus on their interaction with hypoxia-inducible factors (HIFs), regulation of hypoxic responses and relevance with malignant carcinoma's clinical features, which will offer novel insights on the non-coding RNAs' regulation of cancer cells under hypoxic stress and might aid the identification of new theranostic targets and define new therapeutic strategies for those cancer patients with resistance to radiochemotherapy, because of the ubiquity of tumoral hypoxia.

Expression Differences in BCL2 Family Members between Uveal and Cutaneous Melanomas Account for Varying Sensitivity to BH3 Mimetics

Uveal melanoma (UM) is a subtype of melanoma. Although they share a melanocytic origin with cutaneous melanoma (CM), patients with UM have few treatment options. BCL2 homologous 3 mimetics are small-molecule drugs that mimic proapoptotic BCL2 family members. We compared BCL2 family member expression between UM and CM using immunoblot and The Cancer Genome Atlas transcriptomic analysis. UM has a unique signature of low BFL1 and high PUMA proteins compared with CM and 30 other cancer types, making them an attractive candidate for BCL2 homologous 3 protein mimetics. We tested the efficacy of a BCL2 inhibitor and MCL1 inhibitor (MCL1i) in UM, with viability assays, live-cell imaging, sphere assays, and mouse xenograft models. UM had a higher sensitivity to MCL1i than CM. Overexpression of BFL1 or knockdown of PUMA made the UM more resistant to MCL1i. In contrast, MAPK/extracellular signal‒regulated kinase inhibitor treatment in CM made them more sensitive to MCL1i. However, MCL1i-alone treatment was not very effective to reduce the UM initiating cells; to overcome this, we employed a combination of MCL1i with BCL2 inhibitor that synergistically inhibited UM initiating cell's capacity to expand. Overall, we identify a distinct expression profile of BCL2 family members for UM that makes them susceptible to BCL2 homologous 3 mimetics.

BIRC7 is Beneficial for Melanoma Progression and Hypoxic Response

Background

Cutaneous melanoma (CM) accounts for about 90% of all melanoma cases. HIF-1α overexpression is associated with poor prognosis in many cancers including CM. Hence, we characterized differentially expressed genes (DEGs) in the response of CM cells to normoxia and hypoxia.

Methods

We first successfully constructed cell hypoxia model and then performed RNA-seq to explore the changes of gene transcription in CM cells during hypoxia. The highest expression of the six genes was detected using qRT-PCR and Western blot assays. The binding sites between BIRC7 promoter and HIF-1α was explored by luciferase assay. Cellular function assays were used to observe the role of BIRC7 in the effect of hypoxia on tumor progression.

Results

Compared with the transcriptome data of the control group, a total of 2601 DEGs were identified in the hypoxic group. There were 1517 genes with significantly higher expression and 1084 genes with lower expression in the hypoxic group. Among them, OSCAR, BIRC7, HBA1, SFN, GOLT1A, and BEX2 were significantly up-regulated in the hypoxic group. BIRC7 expression was most significantly up-regulated and a downstream factor of HIF-1α. We highlighted that knockdown of BIRC7 reversed the positive effects of HIF-1α on A875 and M14 cells.

Conclusion

Our findings demonstrated that BIRC7 was a downstream factor of HIF-1α and reversed the effect of hypoxia on promoting tumor progression of CM cells.

Anti-Tumor Effect of IDF-11774, an Inhibitor of Hypoxia-Inducible Factor-1, on Melanoma

Melanoma is one of the most aggressive skin cancers. Hypoxia contributes to the aggressiveness of melanoma by promoting cancer growth and metastasis. Upregulation of cyclin D1 can promote uncontrolled cell proliferation in melanoma, whereas stimulation of cytotoxic T cell activity can inhibit it. Epithelial mesenchymal transition (EMT) plays a critical role in melanoma metastasis. Hypoxia-inducible factor-1α (HIF-1α) is a main transcriptional mediator that regulates many genes related to hypoxia. CoCl₂ is one of the most commonly used hypoxia-mimetic chemicals in cell culture. In this study, inhibitory effects of IDF-11774, an inhibitor of HIF-1α, on melanoma growth and metastasis were examined using cultured B16F10 mouse melanoma cells and nude mice transplanted with B16F10 melanoma cells in the presence or absence of CoCl₂-induced hypoxia. IDF-11774 reduced HIF-1α upregulation and cell survival, but increased cytotoxicity of cultured melanoma cells under CoCl₂-induced hypoxia. IDF-11774 also reduced tumor size and local invasion of B16F10 melanoma in nude mice along with HIF-1α downregulation. Expression levels of cyclin D1 in melanoma were increased by CoCl₂ but decreased by IDF-11774. Apoptosis of melanoma cells and infiltration of cytotoxic T cells were increased in melanoma after treatment with IDF-11774. EMT was stimulated by CoCl₂, but restored by IDF-11774. Overall, IDF-11774 inhibited the growth and metastasis of B16F10 melanoma via HIF-1α downregulation. The growth of B16F10 melanoma was inhibited by cyclin D1 downregulation and cytotoxic T cell stimulation. Metastasis of B16F10 melanoma was inhibited by EMT suppression.

Identification of Transcriptional Heterogeneity and Construction of a Prognostic Model for Melanoma Based on Single-Cell and Bulk Transcriptome Analysis

Melanoma is one of the most aggressive and heterogeneous life-threatening cancers. However, the heterogeneity of melanoma and its impact on clinical outcomes are largely unknown. In the present study, intra-tumoral heterogeneity of melanoma cell subpopulations was explored using public single-cell RNA sequencing data. Marker genes, transcription factor regulatory networks, and gene set enrichment analysis were further analyzed. Marker genes of each malignant cluster were screened to create a prognostic risk score, and a nomogram tool was further generated to predict the prognosis of melanoma patients. It was found that malignant cells were divided into six clusters by different marker genes and biological characteristics in which the cell cycling subset was significantly correlated with unfavorable clinical outcomes, and the Wnt signaling pathway-enriched subset may be correlated with the resistance to immunotherapy. Based on the malignant marker genes, melanoma patients in TCGA datasets were divided into three groups which had different survival rates and immune infiltration states. Five malignant cell markers (PSME2, ARID5A, SERPINE2, GPC3, and S100A11) were selected to generate a prognostic risk score. The risk score was associated with overall survival independent of routine clinicopathologic characteristics. The nomogram tool showed good performance with an area under the curve value of 0.802.

Tetraspanin CD9 Expression Predicts Sentinel Node Status in Patients with Cutaneous Melanoma

The tetraspanin CD9 is considered a metastasis suppressor in many cancers, however its role is highly debated. Currently, little is known about CD9 prognostic value in cutaneous melanoma. Our aim was to analyse CD9 expression in melanocytic nevi and primary cutaneous melanomas through immunohistochemistry and immunofluorescence approaches to determine its correlation with invasiveness and metastatic potential. CD9 displayed homogeneous staining in all melanocytic nevi. In contrast, it showed a complete loss of reactivity in all thin melanomas. Interestingly, CD9 was re-expressed in 46% of intermediate and thick melanomas in small tumor clusters predominantly located at sites of invasion near or inside the blood or lymphatic vessels. The most notable finding is that all CD9 stained melanomas presented sentinel node positivity. Additionally, a direct association between CD9 expression and presence of distant metastasis was reported. Finally, we confirm that CD9 expression is consistent with an early protective role against tumorigenesis, however, our data endorse in melanoma a specific function of CD9 in vascular dissemination during late tumor progression. The presence of CD9 hotspots could be essential for melanoma cell invasion in lymphatic and endothelial vessels. CD9 could be a valid prognostic factor for lymph node metastasis risk.

Bcl-2-like protein-10 increases aggressive features of melanoma cells

Aim:

B-cell lymphoma-2 (Bcl-2)-like protein-10 (Bcl2L10) is the less studied member of Bcl-2 family proteins, with the controversial role in different cancer histotypes. Very recently, Bcl2L10 expression in melanoma tumor specimens and its role in melanoma response to therapy have been demonstrated. Here, the involvement of Bcl2L10 on the in vitro and in vivo properties associated with melanoma aggressive features has been investigated.

Methods:

Endogenous Bcl2L10 protein expression was detected by western blotting analysis in a panel of patient-derived and commercially available human melanoma cells. In vitro assays to evaluate clonogenicity, cell proliferation, cell migration, cell invasion, and in vitro capillary-like structure formation [vasculogenic mimicry (VM)] have been performed by using human melanoma cells stably overexpressing Bcl2L10 or transiently transfected for loss/gain function of Bcl2L10, grown under two- or three-dimensional (3D) conditions Xenograft melanoma model was employed to evaluate in vivo tumor growth and angiogenesis.

Results:

Results demonstrated that Bcl2L10 acts as an inducer of in vitro cell migration, invasion, and VM, while in vitro cell proliferation, in vivo tumor growth, as well as colony formation properties were not affected. Dissecting different signaling pathways, it was found that Bcl2L10 positively affects the phosphorylation of extracellular-signal-regulated kinase (ERK) and the expression of markers of cell invasion, such as urokinase plasminogen activator receptor (uPAR) and matrix metalloproteinases (MMPs). Of note, Bcl2L10-dependent in vitro migration, invasion, and VM are linked to uPAR. Bcl2L10 also negatively regulates the intracellular calcium level. Finally, reduced invasion capability in 3D spheroid invasion assay of melanoma cells transiently overexpressing Bcl2L10 was observed after treatment with inhibitors of MMPs and uPAR.

Conclusions:

Overall, data reported in this paper provide evidence supporting a positive role of Bcl2L10 in melanoma aggressive features.

Tracking of Melanoma Cell Plasticity by Transcriptional Reporters

Clonal evolution and cellular plasticity are the genetic and non-genetic driving forces of tumor heterogeneity, which in turn determine tumor cell responses towards therapeutic drugs. Several lines of evidence suggest that therapeutic interventions foster the selection of drug-resistant neural crest stem-like cells (NCSCs) that establish minimal residual disease (MRD) in melanoma. Here, we establish a dual-reporter system, enabling the tracking of NGFR expression and mRNA stability and providing insights into the maintenance of NCSC states. We observed that a transcriptional reporter that contained a 1-kilobase fragment of the human NGFR promoter was activated only in a minor subset (0.72 ± 0.49%, range 0.3–1.5), and ~2–4% of A375 melanoma cells revealed stable NGFR mRNA. The combination of both reporters provides insights into phenotype switching and reveals that both cellular subsets gave rise to cellular heterogeneity. Moreover, whole transcriptome profiling and gene-set enrichment analysis (GSEA) of the minor cellular subset revealed hypoxia-associated programs that might serve as potential drivers of an in vitro switching of NGFR-associated phenotypes and relapse of post-BRAF inhibitor-treated tumors. Concordantly, we observed that the minor cellular subset increased in response to dabrafenib over time. In summary, our reporter-based approach provides insights into plasticity and identified a cellular subset that might be responsible for the establishment of MRD in melanoma.

The Impact of Hyaluronan on Tumor Progression in Cutaneous Melanoma

The incidence of cutaneous melanoma is rapidly increasing worldwide. Cutaneous melanoma is an aggressive type of skin cancer, which originates from malignant transformation of pigment producing melanocytes. The main risk factor for melanoma is ultraviolet (UV) radiation, and thus it often arises from highly sun-exposed skin areas and is characterized by a high mutational burden. In addition to melanoma-associated mutations such as BRAF, NRAS, PTEN and cell cycle regulators, the expansion of melanoma is affected by the extracellular matrix surrounding the tumor together with immune cells. In the early phases of the disease, hyaluronan is the major matrix component in cutaneous melanoma microenvironment. It is a high-molecular weight polysaccharide involved in several physiological and pathological processes. Hyaluronan is involved in the inflammatory reactions associated with UV radiation but its role in melanomagenesis is still unclear. Although abundant hyaluronan surrounds epidermal and dermal cells in normal skin and benign nevi, its content is further elevated in dysplastic lesions and local tumors. At this stage hyaluronan matrix may act as a protective barrier against melanoma progression, or alternatively against immune cell attack. While in advanced melanoma, the content of hyaluronan decreases due to altered synthesis and degradation, and this correlates with poor prognosis. This review focuses on hyaluronan matrix in cutaneous melanoma and how the changes in hyaluronan metabolism affect the progression of melanoma.

Vitamin D Enhances Anticancer Properties of Cediranib, a VEGFR Inhibitor, by Modulation of VEGFR2 Expression in Melanoma Cells

Regardless of the recent groundbreaking introduction of personalized therapy, melanoma continues to be one of the most lethal skin malignancies. Still, a substantial proportion of patients either fail to respond to the therapy or will relapse over time, representing a challenging clinical problem. Recently, we have shown that vitamin D enhances the effectiveness of classical chemotherapeutics in the human malignant melanoma A375 cell line. In search for new combination strategies and adjuvant settings to improve melanoma patient outcomes in the current study, the effects of cediranib (AZD2171), an oral tyrosine kinase inhibitor of VEGFR1-3, PDGFR, and c-KIT, used in combination either with 1,25(OH)₂D₃ or with low-calcemic analog calcipotriol were tested on four human malignant melanoma cell lines (A375, MNT-1, RPMI-7951, and SK-MEL-28). Melanoma cells were pretreated with vitamin D and subsequently exposed to cediranib. We observed a marked decrease in melanoma cell proliferation (A375 and SK-MEL-28), G2/M cell cycle arrest, and a significant decrease in melanoma cell mobility in experimental conditions used (A375). Surprisingly, concurrently with a very desirable decrease in melanoma cell proliferation and mobility, we noticed the upregulation of VEGFR2 at both protein and mRNA levels. No effect of vitamin D was observed in MNT-1 and RPMI-7951 melanoma cells. It seems that vitamin D derivatives enhance cediranib efficacy by modulation of VEGFR2 expression in melanoma cells expressing VEGFR2. In conclusion, our experiments demonstrated that vitamin D derivatives hold promise as novel adjuvant candidates to conquer melanoma, especially in patients suffering from vitamin D deficiency. However, further extensive research is indispensable to reliably assess their potential benefits for melanoma patients.

Acidic and Hypoxic Microenvironment in Melanoma: Impact of Tumour Exosomes on Disease Progression

The mechanisms of melanoma progression have been extensively studied in the last decade, and despite the diagnostic and therapeutic advancements pursued, malignant melanoma still accounts for 60% of skin cancer deaths. Therefore, research efforts are required to better define the intercellular molecular steps underlying the melanoma development. In an attempt to represent the complexity of the tumour microenvironment (TME), here we analysed the studies on melanoma in acidic and hypoxic microenvironments and the interactions with stromal and immune cells. Within TME, acidity and hypoxia force melanoma cells to adapt and to evolve into a malignant phenotype, through the cooperation of the tumour-surrounding stromal cells and the escape from the immune surveillance. The role of tumour exosomes in the intercellular crosstalk has been generally addressed, but less studied in acidic and hypoxic conditions. Thus, this review aims to summarize the role of acidic and hypoxic microenvironment in melanoma biology, as well as the role played by melanoma-derived exosomes (Mexo) under these conditions. We also present a perspective on the characteristics of acidic and hypoxic exosomes to disclose molecules, to be further considered as promising biomarkers for an early detection of the disease. An update on the use of exosomes in melanoma diagnosis, prognosis and response to treatment will be also provided and discussed.

The association of obstructive sleep apnea with melanoma incidence and mortality: a meta-analysis of 5,276,451 patients

BACKGROUND

Melanoma is the most aggressive and lethal form of skin cancer. While emerging in-vivo evidence suggests that intermittent hypoxia, a hallmark feature of obstructive sleep apnea (OSA), may induce melanoma tumorigenesis, the epidemiological association between OSA and melanoma has been inconsistent.

METHODS

We performed a literature search of PubMed, Embase, Scopus and Cochrane Library from inception until 6 June 2021. Two reviewers independently selected randomized trials or observational studies that reported the association of OSA with melanoma incidence or mortality in adults, in comparison to participants with no OSA. Two reviewers independently extracted relevant data and assessed the quality of evidence using the GRADE framework and the Newcastle-Ottawa Scale (NOS). We pooled data using an inverse variance-weighted meta-analysis and ran pre-specified subgrourp analyses.

RESULTS

The meta-analysis included six studies out of 1897 records, comprising a combined cohort of 5,276,451 patients. All studies were adjusted for covariates, with majority of studies adjusting for age (N=5) and sex (N = 4). Compared to those without OSA, patients with OSA had 71% higher pooled hazards of melanoma (HR = 1.71; 95% CI: 1.08-2.69, I² = 99%). Subgroup analyses for studies with (1) median follow-up duration of at least five years, (2) prospective study design, (3) adjustment for obesity yielded HRs of 1.88 (95%CI:1.32-2.67, N = 5), 1.11 (95%CI:0.77-1.60, N = 2) and 1.52 (95%CI:0.75-3.08, N = 3) respectively. One study investigating the relationship between OSA and melanoma mortality detected no association. There were insufficient studies to assess publication bias.

CONCLUSIONS

Meta-analysis of mainly retrospective observational studies, with significant heterogeneity, suggests increased melanoma incidence in OSA patients. Future studies should prospectively explore the differential risk of melanoma for varying OSA severity, and whether timely OSA treatment may mitigate this risk.

Heterogeneity of Melanoma Cell Responses to Sleep Apnea-Derived Plasma Exosomes and to Intermittent Hypoxia

Obstructive sleep apnea (OSA) is associated with increased cutaneous melanoma incidence and adverse outcomes. Exosomes are secreted by most cells, and play a role in OSA-associated tumor progression and metastasis. We aimed to study the effects of plasma exosomes from OSA patients before and after adherent treatment with continuous positive airway pressure (CPAP) on melanoma cells lines, and also to identify exosomal miRNAs from melanoma cells exposed to intermittent hypoxia (IH) or normoxia. Plasma-derived exosomes were isolated from moderate-to-severe OSA patients before (V1) and after (V2) adherent CPAP treatment for one year. Exosomes were co-incubated with three3 different melanoma cell lines (CRL 1424; CRL 1619; CRL 1675) that are characterized by genotypes involving different mutations in BRAF, STK11, CDKN2A, and PTEN genes to assess the effect of exosomes on cell proliferation and migration, as well as on pAMK activity in the presence or absence of a chemical activator. Subsequently, CRL-1424 and CRL-1675 cells were exposed to intermittent hypoxia (IH) and normoxia, and exosomal miRNAs were identified followed by GO and KEG pathways and gene networks. The exosomes from these IH-exposed melanoma cells were also administered to THP1 macrophages to examine changes in M1 and M2 polarity markers. Plasma exosomes from V1 increased CRL-1424 melanoma cell proliferation and migration compared to V2, but not the other two cell lines. Exposure to CRL-1424 exosomes reduced pAMPK/tAMPK in V1 compared to V2, and treatment with AMPK activator reversed the effects. Unique exosomal miRNAs profiles were identified for CRL-1424 and CRL-1675 in IH compared to normoxia, with six miRNAs being regulated and several KEGG pathways were identified. Two M1 markers (CXCL10 and IL6) were significantly increased in monocytes when treated with exosomes from IH-exposed CRL-1424 and CRL-1625 cells. Our findings suggest that exosomes from untreated OSA patients increase CRL-1424 melanoma malignant properties, an effect that is not observed in two other melanoma cell lines. Exosomal cargo from CRL-1424 cells showed a unique miRNA signature compared to CRL-1675 cells after IH exposures, suggesting that melanoma cells are differentially susceptible to IH, even if they retain similar effects on immune cell polarity. It is postulated that mutations in STK-11 gene encoding for the serine/threonine kinase family that acts as a tumor suppressor may underlie susceptibility to IH-induced metabolic dysfunction, as illustrated by CRL-1424 cells.

Artesunate Suppresses Choroidal Melanoma Vasculogenic Mimicry Formation and Angiogenesis via the Wnt/CaMKII Signaling Axis

Angiogenesis and vasculogenic mimicry (VM) are considered to be the main processes to ensure tumor blood supply during the proliferation and metastasis of choroidal melanoma (CM). The traditional antimalarial drug artesunate (ART) has some potential anti-CM effects; however, the underlying mechanisms remain unclarified. Recent studies have shown that the Wnt5a/calmodulin-dependent kinase II (CaMKII) signaling pathway has a close correlation with angiogenesis and VM formation. This study demonstrated that ART eliminated VM formation by inhibiting the aforementioned signaling pathway in CM cells. The microvessel sprouting of the mouse aortic rings and the microvessel density of chicken chorioallantoic membrane (CAM) decreased significantly after ART treatment. VM formation assay and periodic acid schiff (PAS) staining revealed that ART inhibited VM formation in CM. Moreover, ART downregulated the expression levels of the angiogenesis-related proteins vascular endothelial growth factor receptor (VEGFR) 2, platelet-derived growth factor receptor (PDGFR) and vascular endothelial growth factor (VEGF) A, and VM-related proteins ephrin type-A receptor (EphA) 2 and vascular endothelial (VE)-cadherin. The expression of hypoxia-inducible factor (HIF)-1α, Wnt5a, and phosphorylated CaMKII was also downregulated after ART treatment. In addition, we further demonstrated that ART inhibited the proliferation, migration, and invasion of OCM-1 and C918 cells. Collectively, our results suggested that ART inhibited angiogenesis and VM formation of choroidal melanoma likely by regulating the Wnt5a/CaMKII signaling pathway. These findings further supported the feasibility of ART for cancer therapy.

Special Issue "Precision Oncology in Melanoma Progression"

Melanoma represents the most malignant type of skin cancer, with increasing incidence worldwide [...].