Melanocytes in development and cancer

Melanin Biopolymers in Pharmacology and Medicine-Skin Pigmentation Disorders, Implications for Drug Action, Adverse Effects and Therapy

Melanins are biopolymeric pigments formed by a multi-step oxidation process of tyrosine in highly specialized cells called melanocytes. Melanin pigments are mainly found in the skin, iris, hair follicles, and inner ear. The photoprotective properties of melanin biopolymers have been linked to their perinuclear localization to protect DNA, but their ability to scavenge metal ions and antioxidant properties has also been noted. Interactions between drugs and melanins are of clinical relevance. The formation of drug-melanin complexes can affect both the efficacy of pharmacotherapy and the occurrence of adverse effects such as phototoxic reactions and discoloration. Because the amount and type of melanin synthesized in the body is subject to multifactorial regulation-determined by both internal factors such as genetic predisposition, inflammation, and hormonal balance and external factors such as contact with allergens or exposure to UV radiation-different effects on the melanogenesis process can be observed. These factors can directly influence skin pigmentation disorders, resulting in hypopigmentation or hyperpigmentation of a genetic or acquired nature. In this review, we will present information on melanocyte biology, melanogenesis, and the multifactorial influence of melanin on pharmacological parameters during pharmacotherapy. In addition, the types of skin color disorders, with special emphasis on the process of their development, symptoms, and methods of treatment, are presented in this article.

Final results of urelumab, an anti-CD137 agonist monoclonal antibody, in combination with cetuximab or nivolumab in patients with advanced solid tumors

BACKGROUND

Resistance to immune checkpoint inhibitors and targeted treatments for cancer is common; thus, novel immunotherapy agents are needed. Urelumab is a monoclonal antibody agonist that binds to CD137 receptors expressed on T cells. Here, we report two studies that evaluated urelumab in combination with cetuximab or nivolumab in patients with select, advanced solid tumors.

METHODS

CA186-018: Patients with metastatic colorectal cancer or metastatic squamous cell carcinoma of the head and neck (SCCHN) were treated in a dose-evaluation phase with urelumab 0.1 mg/kg (urelumab-0.1) every 3 weeks (Q3W)+cetuximab 250 mg/m2 (cetuximab-250) weekly; and in a dose-expansion phase with urelumab 8 mg flat dose (urelumab-8) Q3W+cetuximab-250 weekly. CA186-107: The dose-escalation phase included patients with previously treated advanced solid tumors (or treated or treatment-naive melanoma); patients received urelumab 3 mg flat dose (urelumab-3) or urelumab-8 every 4 weeks+nivolumab 3 mg/kg (nivolumab-3) or 240 mg (nivolumab-240) every 2 weeks. In the expansion phase, patients with melanoma, non-small cell lung cancer, or SCCHN were treated with urelumab-8+nivolumab-240. Primary endpoints were safety and tolerability, and the secondary endpoint included efficacy assessments.

RESULTS

CA186-018: 66 patients received study treatment. The most frequent treatment-related adverse events (TRAEs) were fatigue (75%; n=3) with urelumab-0.1+cetuximab-250 and dermatitis (45%; n=28) with urelumab-8+cetuximab-250. Three patients (5%) discontinued due to TRAE(s) (with urelumab-8+cetuximab-250). One patient with SCCHN had a partial response (objective response rate (ORR) 5%, with urelumab-8+cetuximab-250).CA186-107: 134 patients received study treatment. Fatigue was the most common TRAE (32%; n=2 with urelumab-3+nivolumab-3; n=1 with urelumab-8+nivolumab-3; n=40 with urelumab-8+nivolumab-240). Nine patients (7%) discontinued due to TRAE(s) (n=1 with urelumab-3+nivolumab-3; n=8 with urelumab-8+nivolumab-240). Patients with melanoma naive to anti-PD-1 therapy exhibited the highest ORR (49%; n=21 with urelumab-8+nivolumab-240). Intratumoral gene expression in immune-related pathways (CD3, CD8, CXCL9, GZMB) increased on treatment with urelumab+nivolumab.

CONCLUSIONS

Although the addition of urelumab at these doses was tolerable, preliminary response rates did not indicate an evident additive benefit. Nevertheless, the positive pharmacodynamics effects observed with urelumab and the high response rate in treatment-naive patients with melanoma warrant further investigation of other anti-CD137 agonist agents for treatment of cancer.

TRIAL REGISTRATION NUMBERS

NCT02110082; NCT02253992.

Microrheological comparison of melanoma cells by atomic force microscopy

Melanoma is one of the most severe cancers due to its great potential to form metastasis. Recent studies showed the importance of mechanical property assessment in metastasis formation which depends on the cytoskeleton dynamics and cell migration. Although cells are considered purely elastic, they are viscoelastic entities. Microrheology atomic force microscopy (AFM) enables the assessment of elasticity and viscous properties, which are relevant to cell behavior regulation. The current work compares the mechanical properties of human neonatal primary melanocytes (HNPMs) with two melanoma cell lines (WM793B and 1205LU cells), using microrheology AFM. Immunocytochemistry of F-actin filaments and phosphorylated focal adhesion kinase (p-FAK) and cell migration assays were performed to understand the differences found in microrheology AFM regarding the tumor cell lines tested. AFM revealed that HNPMs and tumor cell lines had distinct mechanical properties. HNPMs were softer, less viscous, presenting a higher power-law than melanoma cells. Immunostaining showed that metastatic 1205LU cells expressed more p-FAK than WM793B cells. Melanoma cell migration assays showed that WM73B did not close the gap, in contrast to 1205LU cells, which closed the gap at the end of 23 h. These data seem to corroborate the high migratory behavior of 1205LU cells. Microrheology AFM applied to HNPMs and melanoma cells allowed the quantification of elasticity, viscous properties, glassy phase, and power-law properties, which have an impact in cell migration and metastasis formation. AFM study is important since it can be used as a biomarker of the different stages of the disease in melanoma.

Re-examining the evidence that ivermectin induces a melanoma-like state in Xenopus embryos

Modeling metastasis in animal systems has been an important focus for developing cancer therapeutics. Xenopus laevis is a well-established model, known for its use in identifying genetic mechanisms underlying diseases and disorders in humans. Prior literature has suggested that the drug, ivermectin, can be used in Xenopus to induce melanocytes to convert into a metastatic melanoma-like state, and thus could be ideal for testing possible melanoma therapies in vivo. However, there are notable inconsistencies between ivermectin studies in Xenopus and the application of ivermectin in mammalian systems, that are relevant to cancer and melanoma research. In this review, we examine the ivermectin-induced phenotypes in Xenopus, and we explore the current uses of ivermectin in human research. We conclude that while ivermectin may be a useful drug for many biomedical purposes, it is not ideal to induce a metastatic melanocyte phenotype in Xenopus for testing the effects of potential melanoma therapeutics.

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.

Whole-exome sequencing reveals mutational profiles of anorectal and gynecological melanoma

Mucosal melanoma is a rare and highly malignant type of melanoma. Among the sites that mucosal melanoma arises, anorectal and gynecological melanoma has more aggressive behavior and worse prognosis. There was no effective therapy for mucosal melanoma at present. Only a small number of mucosal melanoma patients which harbor mutations in BRAF or KIT benefit from targeted therapy. So it's an urgent need to identify more actionable mutations in mucosal melanoma. To identify more potential therapeutic targets in mucosal melanoma, 48 samples were collected from 44 patients with anorectal or gynecological melanoma and subjected to whole-exome sequencing. The tumor mutation burden was low with a median of 1.75 mutations per Mb. In chromosomal level, 1q, 6p and 8q of mucosal melanoma were significantly amplified while 9p, 10p, 10q, 16p and 16q were significantly deleted. Muc16 was the most frequently mutated oncogene in our samples(25%). The mutation frequency of KIT(20%) was comparable to the "triple-wild" genes-NRAS(20%), NF1(20%), and BRAF(11%). KMT2D mutation was found in 18.18% patients, which is previously unidentified. MAPK signaling pathway and lysine degradation were the most frequently mutated pathways. Moreover, patients with TP53 mutations tend to have worse clinical outcome (median survival time 19 vs. 50 months, log-rank P = 0.006). 2000 ore mutated genes involved in MAPK signaling pathway were identified, which expand the patients potentially benefit from ample MAPK inhibitors. KMT2D could be a potential therapeutic target. Moreover, TP53 could be a potential prognosis marker for mucosal melanoma.

Effects of Nanosecond Pulsed Electric Field on Immune Checkpoint Receptors in Melanoma Cells

Checkpoint molecules such as PD-1, LAG-3, and TIM-3 are currently under extensive investigation for their roles in the attenuation of the immune response in cancer. Various methods have been applied to overcome the challenges in this field. This study investigated the effects of nanosecond pulsed electric field (nsPEF) treatment on the expression of immune checkpoint molecules in A375 and C32 melanoma cells. The researchers found that the nsPEF treatment was able to enhance membrane permeabilization and morphological changes in the cell membrane without being cytotoxic. We found that the effects of nsPEFs on melanoma included (1) the transport of vesicles from the inside to the outside of the cells, (2) cell contraction, and (3) the migration of lipids from inside the cells to their peripheries. The treatment increased the expression of PD-1 checkpoint receptors. Furthermore, we also observed potential co-localization or clustering of MHC class II and PD-1 molecules on the cell surface and the secretion of cytokines such as TNF-α and IL-6. These findings suggest that nsPEF treatment could be a viable approach to enhance the delivery of therapeutic agents to cancer cells and to modulate the tumor microenvironment to promote an antitumor immune response. Further studies are needed to explore the mechanisms underlying these effects and their impacts on the antitumor immune response, and to investigate the potential of nsPEF treatment in combination with immune checkpoint inhibitors to improve clinical outcomes for cancer patients.

Preparation of chitosan nanoparticles for simultaneous drug delivery of dacarbazine and enoxaparin in melanoma

The aim of this study was to investigate the anti-melanoma and anti-angiogenic effects of enoxaparin surface-coated dacarbazine-loaded chitosan nanoparticles (Enox-Dac-Chi NPs). The prepared Enox-Dac-Chi NPs had a particle size of 367.95 ± 1.84 nm, zeta potential of -7.12 ± 0.25 mV, efficiency of drug loading (DL%) of 73.90 ± 3.84 %, and attached enoxaparin percentage of 98.53 ± 0.96 %. Both drugs had extended-release profiles and approximately 96 % of enoxaparin and 67 % dacarbazine were released within 8 h. The Enox-Dac-Chi NPs with IC₅₀ of 59.60 ± 1.25 μg/ml were the most cytotoxic against melanoma cancer cells compared with chitosan nanoparticles containing only dacarbazine (Dac-Chi NPs) and free dacarbazine. There was no significant difference between the cellular uptake of Chi NPs and enoxaparin coated Chi NPs (Enox-Chi NPs) in B16F10 cells. Enox-Chi NPs with an average anti-angiogenic score of 1.75 ± 0.125 had more anti-angiogenic effect than enoxaparin. The results showed that simultaneous delivery of dacarbazine and enoxaparin by chitosan nanoparticles can enhance the anti-melanoma effect of dacarbazine. Additionally, enoxaparin can prevent the melanoma metastasis by its anti-angiogenic activity. Thus, the designed nanoparticles can be introduced as effective drug delivery vehicles for the treatment and prevention of metastatic melanoma.

Neurosarcomatous amelanotic transformation of malignant melanoma presenting as malignant periopheral nerve sheath tumor: Rare case report

RATIONALE

Malignant melanoma (MM) is notorious for its remarkable morphological variation and aberrant histopathological patterns. In addition, Malignant Periopheral Nerve Sheath Tumor (MPNST) is an uncommon but aggressive soft tissue sarcoma. Because of the common embryological origin of melanocytes and Schwann cells in the neural crest, discriminating between a particular type of MM and MPNST can be difficult, particularly when they are amelanotic. Our goal is to increase awareness among clinicians of the rare variations of MM and the importance of medical history in improving the accuracy of the final clinical diagnosis.

PATIENT CONCERNS

A 68-year-old man was admitted to the hospital due to pain in his right ankle, which had persisted for 8 months, along with swelling for 4 months. Medical history revealed delayed healing of right plantar for 5 years after a traumatic injury.

DIAGNOSES

The ankle mass was initially diagnosed as MPNST through biopsy. After reviewing the patient's medical history and receiving the final pathological report following amputation, we have revised the diagnosis to metastatic amelanotic desmoplastic melanoma in the ankle part and lentigo maligna melanoma in the plantar part. This is due to both lesions displaying positive markers or mutated genes in immunohistology and Gene Mutation Detection, indicating homology between the 2 tumors.

INTERVENTIONS

Due to the malignant characteristics of the tumor and the patient's wishes, amputation of the right lower leg was carried out.

OUTCOMES

Subsequently, the patient was treated with interferon-γ and immunosuppressant PD-1 inhibitor, and survived for 1 year after amputation.

LESSONS

Clinical data, immunohistochemisty biomarkers and genes detection results can serve as valuable evidence for pathologists and clinicians in identifying the disease process. Collaborative efforts between clinicians and scientists are crucial in order to identify specific markers that can effectively differentiate between the 2 tumors, thereby enhancing the conclusiveness of the diagnosis.

Transformer-Based Approach to Melanoma Detection

Melanoma is a malignant cancer type which develops when DNA damage occurs (mainly due to environmental factors such as ultraviolet rays). Often, melanoma results in intense and aggressive cell growth that, if not caught in time, can bring one toward death. Thus, early identification at the initial stage is fundamental to stopping the spread of cancer. In this paper, a ViT-based architecture able to classify melanoma versus non-cancerous lesions is presented. The proposed predictive model is trained and tested on public skin cancer data from the ISIC challenge, and the obtained results are highly promising. Different classifier configurations are considered and analyzed in order to find the most discriminating one. The best one reached an accuracy of 0.948, sensitivity of 0.928, specificity of 0.967, and AUROC of 0.948.

A comprehensive review on novel targeted therapy methods and nanotechnology-based gene delivery systems in melanoma

Melanoma, a malignant form of skin cancer, has been swiftly increasing in recent years. Although there have been significant advancements in clinical treatment underlying a well-understanding of melanoma-susceptible genes and the molecular basis of melanoma pathogenesis, the permanency of response to therapy is frequently constrained by the emergence of acquired resistance and systemic toxicity. Conventional therapies, including surgical resection, chemotherapy, radiotherapy, and immunotherapy, have already been used to treat melanoma and are dependent on the cancer stage. Nevertheless, ineffective side effects and the heterogeneity of tumors pose major obstacles to the therapeutic treatment of malignant melanoma through such strategies. In light of this, advanced therapies including nucleic acid therapies (ncRNA, aptamers), suicide gene therapies, and gene therapy using tumor suppressor genes, have lately gained immense attention in the field of cancer treatment. Furthermore, nanomedicine and targeted therapy based on gene editing tools have been applied to the treatment of melanoma as potential cancer treatment approaches nowadays. Indeed, nanovectors enable delivery of the therapeutic agents into the tumor sites by passive or active targeting, improving therapeutic efficiency and minimizing adverse effects. Accordingly, in this review, we summarized the recent findings related to novel targeted therapy methods as well as nanotechnology-based gene systems in melanoma. We also discussed current issues along with potential directions for future research, paving the way for the next-generation of melanoma treatments.

An epigenetic switch controls an alternative NR2F2 isoform that unleashes a metastatic program in melanoma

Metastatic melanoma develops once transformed melanocytic cells begin to de-differentiate into migratory and invasive melanoma cells with neural crest cell (NCC)-like and epithelial-to-mesenchymal transition (EMT)-like features. However, it is still unclear how transformed melanocytes assume a metastatic melanoma cell state. Here, we define DNA methylation changes that accompany metastatic progression in melanoma patients and discover Nuclear Receptor Subfamily 2 Group F, Member 2 - isoform 2 (NR2F2-Iso2) as an epigenetically regulated metastasis driver. NR2F2-Iso2 is transcribed from an alternative transcriptional start site (TSS) and it is truncated at the N-terminal end which encodes the NR2F2 DNA-binding domain. We find that NR2F2-Iso2 expression is turned off by DNA methylation when NCCs differentiate into melanocytes. Conversely, this process is reversed during metastatic melanoma progression, when NR2F2-Iso2 becomes increasingly hypomethylated and re-expressed. Our functional and molecular studies suggest that NR2F2-Iso2 drives metastatic melanoma progression by modulating the activity of full-length NR2F2 (Isoform 1) over EMT- and NCC-associated target genes. Our findings indicate that DNA methylation changes play a crucial role during metastatic melanoma progression, and their control of NR2F2 activity allows transformed melanocytes to acquire NCC-like and EMT-like features. This epigenetically regulated transcriptional plasticity facilitates cell state transitions and metastatic spread.

A Comprehensive Analysis of Cutaneous Melanoma Patients in Greece Based on Multi-Omic Data

Cutaneous melanoma (CM) is the most aggressive type of skin cancer, and it is characterised by high mutational load and heterogeneity. In this study, we aimed to analyse the genomic and transcriptomic profile of primary melanomas from forty-six Formalin-Fixed, Paraffin-Embedded (FFPE) tissues from Greek patients. Molecular analysis for both germline and somatic variations was performed in genomic DNA from peripheral blood and melanoma samples, respectively, exploiting whole exome and targeted sequencing, and transcriptomic analysis. Detailed clinicopathological data were also included in our analyses and previously reported associations with specific mutations were recognised. Most analysed samples (43/46) were found to harbour at least one clinically actionable somatic variant. A subset of samples was profiled at the transcriptomic level, and it was shown that specific melanoma phenotypic states could be inferred from bulk RNA isolated from FFPE primary melanoma tissue. Integrative bioinformatics analyses, including variant prioritisation, differential gene expression analysis, and functional and gene set enrichment analysis by group and per sample, were conducted and molecular circuits that are implicated in melanoma cell programmes were highlighted. Integration of mutational and transcriptomic data in CM characterisation could shed light on genes and pathways that support the maintenance of phenotypic states encrypted into heterogeneous primary tumours.

Redundancy analysis, genome-wide association studies and the pigmentation of brown trout (Salmo trutta L.)

The association of molecular variants with phenotypic variation is a main issue in biology, often tackled with genome-wide association studies (GWAS). GWAS are challenging, with increasing, but still limited, use in evolutionary biology. We used redundancy analysis (RDA) as a complimentary ordination approach to single- and multitrait GWAS to explore the molecular basis of pigmentation variation in brown trout (Salmo trutta) belonging to wild populations impacted by hatchery fish. Based on 75,684 single nucleotide polymorphic (SNP) markers, RDA, single- and multitrait GWAS allowed the extraction of 337 independent colour patterning loci (CPLs) associated with trout pigmentation traits, such as the number of red and black spots on flanks. Collectively, these CPLs (i) mapped onto 35 out of 40 brown trout linkage groups indicating a polygenic genomic architecture of pigmentation, (ii) were found to be associated with 218 candidate genes, including 197 genes formerly mentioned in the literature associated to skin pigmentation, skin patterning, differentiation or structure notably in a close relative, the rainbow trout (Onchorhynchus mykiss), and (iii) related to functions relevant to pigmentation variation (e.g., calcium- and ion-binding, cell adhesion). Annotated CPLs include genes with well-known pigmentation effects (e.g., PMEL, SLC45A2, SOX10), but also markers associated with genes formerly found expressed in rainbow or brown trout skins. RDA was also shown to be useful to investigate management issues, especially the dynamics of trout pigmentation submitted to several generations of hatchery introgression.

Genomics and Epigenomics in the Molecular Biology of Melanoma-A Prerequisite for Biomarkers Studies

Melanoma is a common and aggressive tumor originating from melanocytes. The increasing incidence of cutaneous melanoma in recent last decades highlights the need for predictive biomarkers studies. Melanoma development is a complex process, involving the interplay of genetic, epigenetic, and environmental factors. Genetic aberrations include BRAF, NRAS, NF1, MAP2K1/MAP2K2, KIT, GNAQ, GNA11, CDKN2A, TERT mutations, and translocations of kinases. Epigenetic alterations involve microRNAs, non-coding RNAs, histones modifications, and abnormal DNA methylations. Genetic aberrations and epigenetic marks are important as biomarkers for the diagnosis, prognosis, and prediction of disease recurrence, and for therapeutic targets. This review summarizes our current knowledge of the genomic and epigenetic changes in melanoma and discusses the latest scientific information.

Cutaneous and acral melanoma cross-OMICs reveals prognostic cancer drivers associated with pathobiology and ultraviolet exposure

Ultraviolet radiation (UV) is causally linked to cutaneous melanoma, yet the underlying epigenetic mechanisms, known as molecular sensors of exposure, have not been characterized in clinical biospecimens. Here, we integrate clinical, epigenome (DNA methylome), genome and transcriptome profiling of 112 cutaneous melanoma from two multi-ethnic cohorts. We identify UV-related alterations in regulatory regions and immunological pathways, with multi-OMICs cancer driver potential affecting patient survival. TAPBP, the top gene, is critically involved in immune function and encompasses several UV-altered methylation sites that were validated by targeted sequencing, providing cost-effective opportunities for clinical application. The DNA methylome also reveals non UV-related aberrations underlying pathological differences between the cutaneous and 17 acral melanomas. Unsupervised epigenomic mapping demonstrated that non UV-mutant cutaneous melanoma more closely resembles acral rather than UV-exposed cutaneous melanoma, with the latter showing better patient prognosis than the other two forms. These gene-environment interactions reveal translationally impactful mechanisms in melanomagenesis.

Activity of ROCKII not ROCKI promotes pulmonary metastasis of melanoma cells via modulating Smad2/3-MMP9 and FAK-Src-VEGF signalling

Rho-associated coiled-coil kinase (ROCK) inhibition decreases tumourogenic growth, proliferation and angiogenesis. Multifaceted evidences are there about the role of ROCK in cancer progression, but isoform specific analysis in secondary pulmonary melanoma is still unaddressed. This study explored the operating function of ROCK in the metastasis of B16F10 mice melanoma cell line. Inhibition by KD-025 indicated dual wielding role of ROCKII as it is associated with the regulation of MMP9 activity responsible for extra-cellular matrix (ECM) degradation as well as angiogenic invasion as an effect of Src-FAK-STAT3 interaction dependent VEGF switching. We found the assisting role of ROCKII, not ROCKI in nuclear localization of Smads that effectively increased MMP9 expression and activity (p < 0.01). This cleaved the protein components of ECM thereby played a crucial role in tissue remodeling at secondary site during establishment of metastatic tumour. ROCKII phosphorylation at Ser¹³⁶⁶ as an activation of the same was imprinted essential for oncogenic molecular bagatelle leading to histo-architectural change of pulmonary tissue with extracellular matrix degradation as a consequence of invasion. Direct correlation of pROCKIISer¹³⁶⁶ with MMP9 as well as VEGF expression in vivo studies cue to demonstrate the importance of pROCKIISer¹³⁶⁶ inhibition in the context of angiogenesis, and metastasis suggesting ROCKII signaling as a possible target for the treatment of secondary lung cancer specially in metastatic melanoma.

lncRNA AGAP2-AS1 Facilitates Tumorigenesis and Ferroptosis Resistance through SLC7A11 by IGF2BP2 Pathway in Melanoma

Long noncoding RNAs (lncRNAs) stand as indispensable regulators of initiation and development in melanoma (melanoma). However, the action molecular mechanisms linked to melanoma remain unclear. In the current study, the findings revealed that AGAP2-AS1 was considerably greater in melanoma than in healthy tissues and that the level of AGAP2-AS1 in cancer tissue was significantly linked to the cancerous TNM stage of patients. Individuals with high AGAP2-AS1 had a considerably shorter survival duration than patients with low AGAP2-AS1, regardless of progression-free survival or overall survival. Functionally, downregulating the expression of AGAP2-AS1 can inhibit the growth of melanocytes. Compared with the control group, AGAP2-AS1 knockdown increased Erastin-mediated iron death in melanoma cells. However, iron death inhibitor FERSINT-1 restored this effect, while Erastin induced melanoma cell death. Besides, intracellular iron and Fe2+ levels increased after AGAP2-AS1 knockdown in melanoma cells treated with Erastin compared with the si-NC group. In addition, AGAP2-AS1 silencing resulted in a significant decrease in glutathione (GSH) content in Erastin-treated melanoma cells. The mechanistic results suggest AGAP2-AS1 increases SLC7A11 mRNA stability through the IGF2BP2 pathway. In this investigation, we discovered new activities for AGAP2-AS1 and firstly discovered its mechanistic basis in ferroptosis and melanoma formation that might help in the search for potential therapy options in melanoma.

HDAC2 Is Involved in the Regulation of BRN3A in Melanocytes and Melanoma

The neural crest transcription factor BRN3A is essential for the proliferation and survival of melanoma cells. It is frequently expressed in melanoma but not in normal melanocytes or benign nevi. The mechanisms underlying the aberrant expression of BRN3A are unknown. Here, we investigated the epigenetic regulation of BRN3A in melanocytes and melanoma cell lines treated with DNA methyltransferase (DNMT), histone acetyltransferase (HAT), and histone deacetylase (HDAC) inhibitors. DNMT and HAT inhibition did not significantly alter BRN3A expression levels, whereas panHDAC inhibition by trichostatin A led to increased expression. Treatment with the isoform-specific HDAC inhibitor mocetinostat, but not with PCI-34051, also increased BRN3A expression levels, suggesting that class I HDACs HDAC1, HDAC2, and HDAC3, and class IV HDAC11, were involved in the regulation of BRN3A expression. Transient silencing of HDACs 1, 2, 3, and 11 by siRNAs revealed that, specifically, HDAC2 inhibition was able to increase BRN3A expression. ChIP-Seq analysis uncovered that HDAC2 inhibition specifically increased H3K27ac levels at a distal enhancer region of the BRN3A gene. Altogether, our data suggest that HDAC2 is a key epigenetic regulator of BRN3A in melanocytes and melanoma cells. These results highlight the importance of epigenetic mechanisms in regulating melanoma oncogenes.

Upregulated Guanine Deaminase Is Involved in Hyperpigmentation of Seborrheic Keratosis via Uric Acid Release

Seborrheic keratosis, which is a benign tumor composed of epidermal keratinocytes, develops common in the elderly. Uric acid generated by upregulated guanine deaminase (GDA) has been identified to cause UV-induced keratinocyte senescence in seborrheic keratosis. Seborrheic keratosis is also frequently pigmented. Growing evidences indicate that hyperuricemia is a risk factor of acanthosis nigricans, an acquired skin hyperpigmentation. The objective of this study was to investigate role of GDA and its metabolic end product, uric acid, in hyperpigmentation of patients with seborrheic keratosis using their lesional and non-lesional skin specimen sets and cultured primary human epidermal keratinocytes with or without GDA overexpression or uric acid treatment. GDA-overexpressing keratinocytes or their conditioned media containing uric acid increased expression levels of MITF and tyrosinase in melanocytes. Uric acid released from keratinocytes was facilitated by ABCG2 transporter with the help of PDZK1 interaction. Released uric acid was taken by URAT1 transporter in melanocytes, stimulating melanogenesis through p38 MAPK activation. Overall, GDA upregulation in seborrheic keratosis plays a role in melanogenesis via its metabolic end product uric acid, suggesting that seborrheic keratosis as an example of hyperpigmentation associated with photoaging.

The Role of the Vitamin D Receptor in the Pathogenesis, Prognosis, and Treatment of Cutaneous Melanoma

Melanoma is the malignant transformation of melanocytes and represents the most lethal form of skin cancer. While early-stage melanoma localized to the skin can be cured with surgical excision, metastatic melanoma often requires a multi-pronged approach and even then can exhibit treatment resistance. Understanding the molecular mechanisms involved in the pathogenesis of melanoma could lead to novel diagnostic, prognostic, and therapeutic strategies to ultimately decrease morbidity and mortality. One emerging candidate that may have value as both a prognostic marker and in a therapeutic context is the vitamin D receptor (VDR). VDR is a nuclear steroid hormone receptor activated by 1,25 dihydroxy-vitamin D3 [calcitriol, 1,25(OH)₂D3]. While 1,25 dihydroxy-vitamin D3 is typically thought of in relation to calcium metabolism, it also plays an important role in cell proliferation, differentiation, programmed-cell death as well as photoprotection. This review discusses the role of VDR in the crosstalk between keratinocytes and melanocytes during melanomagenesis and summarizes the clinical data regarding VDR polymorphisms, VDR as a prognostic marker, and potential uses of vitamin D and its analogs as an adjuvant treatment for melanoma.

High anticancer efficacy of solid lipid nanoparticles containing Zataria multiflora essential oil against breast cancer and melanoma cell lines

Background

The cancer burden is rising rapidly worldwide, and it annually causes about 8.8 million deaths worldwide. Due to chemical drugs’ side effects and the emergence of resistance, the development of new green drugs has received much attention. We aimed to investigate whether solid-lipid nanoparticles containing essential oil of Zataria multiflora (ZMSLN) enhanced the anticancer efficacy of the essential oil against breast cancer (MDA-MB-468) and melanoma (A-375) cells.

Results

ZMSLN was prepared by the high-pressure homogenizer method; particle size 176 ± 8 nm, polydispersity index 0.22 ± 0.1, entrapment efficiency 67 ± 5%. The essential oil showed a dose-dependent antiproliferative effect on MDA-MB-468 and A-375 cells at all examined concentrations (75, 150, 300, 600, and 1200 μg/mL). Interestingly, after treating both cells with 75 μg/mL of ZMSLN, their viabilities were reduced to under 13%.

Conclusion

The finding showed that ZMSLN had a distinct antiproliferative efficacy; it could thus be considered a green anticancer candidate for further in vivo and in vivo studies.

PITX1 inhibits the growth and proliferation of melanoma cells through regulation of SOX family genes

Melanoma is one of the most aggressive types of cancer wherein resistance to treatment prevails. Therefore, it is important to discover novel molecular targets of melanoma progression as potential treatments. Here we show that paired-like homeodomain transcription factor 1 (PITX1) plays a crucial role in the inhibition of melanoma progression through regulation of SRY-box transcription factors (SOX) gene family mRNA transcription. Overexpression of PITX1 in melanoma cell lines resulted in a reduction in cell proliferation and an increase in apoptosis. Additionally, analysis of protein levels revealed an antagonistic cross-regulation between SOX9 and SOX10. Interestingly, PITX1 binds to the SOX9 promoter region as a positive regulatory transcription factor; PITX1 mRNA expression levels were positively correlated with SOX9 expression, and negatively correlated with SOX10 expression in melanoma tissues. Furthermore, transcription of the long noncoding RNA (lncRNA), survival-associated mitochondrial melanoma-specific oncogenic noncoding RNA (SAMMSON), was decreased in PITX1-overexpressing cells. Taken together, the findings in this study indicate that PITX1 may act as a negative regulatory factor in the development and progression of melanoma via direct targeting of the SOX signaling.

PERK mediates resistance to BRAF inhibition in melanoma with impaired PTEN

Targeting mutant BRAF in patients with melanomas harboring this oncogene has been highly successful as a first-line treatment, but other mutations may affect its efficacy and alter the route of acquired resistance resulting in recurrence and poor prognosis. As an evolving strategy, melanoma treatment needs to be expanded to include targets based on newly discovered emerging molecules and pathways. We here show that PERK plays a critical role in BRAF inhibitor-acquired resistance in melanoma with impaired PTEN. Inhibition of PERK by either shRNA or a pharmacological inhibitor blocked the growth of BRAF inhibitor-resistant melanoma with impaired PTEN in vitro and in vivo, suggesting an effective approach against melanomas with mutant BRAF and PTEN deficiency. Our current findings, along with our previous discovery that the AXL/AKT axis mediates resistance to BRAF inhibition in melanoma with wild-type PTEN, provide new insights toward a strategy for combating BRAF inhibition-acquired resistance in BRAF mutant melanoma with different PTEN statuses.

Chitosan nanoparticles containing limonene and limonene-rich essential oils: potential phytotherapy agents for the treatment of melanoma and breast cancers

BACKGROUND

Melanoma and breast cancers are two common cancers worldwide. Due to the side effects of chemotherapy drugs and the occurring resistance against them, the development of green drugs has been received more attention.

METHODS

The anticancer effects of three essential oils from the Citrus family and their identified major constituents (limonene) were first investigated against melanoma and breast cancer cell lines (A-375 and MDA-MB-468). By preparing chitosan nanoparticles containing them, an attempt was then made to improve their effectiveness.

RESULTS

Chitosan nanoparticles containing Citrus sinensis and Citrus limon essential oils with IC₅₀s of 0.03 and 0.124 μg/mL on A-375 cells, and 23.65 and 40.32 μg/mL on MDA-MB-468 showed distinct anticancer efficacies.

CONCLUSION

The prepared formulations could thus be considered as green anticancer agents in complementary medicine and therapies.

Development and in vivo evaluation of fused benzazole analogs of anti-melanoma agent HA15

Background: In line with our recent discovery of an efficient anticancer thiazolebenzenesulfonamide framework HA15 (1) based on a remarkable endoplasmic reticulum stress inducement mode of action, we report herein a series of innovative constrained HA15 analogs, featuring four types of bicylic derivatives. Results: The structure-activity relationship analysis, using a cell line assay, led us to identify a novel version of HA15: a new benzothiazole derivative (10b) exhibiting important anti-melanoma effect against sensitive and resistant melanoma cells. Meanwhile, compound 10b induced a significant tumor growth inhibition in vivo with no apparent signs of toxicity. Conclusion: These results consistently open new directions to improve and develop more powerful anticancer therapeutics harboring this type of fused framework.

A Review of Epidemiology and Cancer Biology of Malignant Melanoma

Malignant melanoma is a neoplasm originating in the melanocytes in the skin. Although malignant melanoma is the third most common cutaneous cancer, it is recognized as the main cause of skin cancer-related mortality, and its incidence is rising. The natural history of malignant melanoma involves an inconsistent and insidious skin cancer with great metastatic potential. Increased ultra-violet (UV) skin exposure is undoubtedly the greatest risk factor for developing cutaneous melanoma; however, a plethora of risk factors are now recognized as causative. Moreover, modern oncology now considers melanoma proliferation a complex, multifactorial process with a combination of genetic, epigenetic, and environmental factors all known to be contributory to tumorgenesis. Herein, we wish to outline the epidemiological, molecular, and biological processes responsible for driving malignant melanoma proliferation.

Methoxy-Substituted Tyramine Derivatives Synthesis, Computational Studies and Tyrosinase Inhibitory Kinetics

Targeting tyrosinase for melanogenesis disorders is an established strategy. Hydroxyl-substituted benzoic and cinnamic acid scaffolds were incorporated into new chemotypes that displayed in vitro inhibitory effects against mushroom and human tyrosinase for the purpose of identifying anti-melanogenic ingredients. The most active compound 2-((4-methoxyphenethyl)amino)-2-oxoethyl (E)-3-(2,4-dihydroxyphenyl) acrylate (Ph9), inhibited mushroom tyrosinase with an IC₅₀ of 0.059 nM, while 2-((4-methoxyphenethyl)amino)-2-oxoethyl cinnamate (Ph6) had an IC₅₀ of 2.1 nM compared to the positive control, kojic acid IC₅₀ 16700 nM. Results of human tyrosinase inhibitory activity in A375 human melanoma cells showed that compound (Ph9) and Ph6 exhibited 94.6% and 92.2% inhibitory activity respectively while the positive control kojic acid showed 72.9% inhibition. Enzyme kinetics reflected a mixed type of inhibition for inhibitor Ph9 (K_i 0.093 nM) and non-competitive inhibition for Ph6 (K_i 2.3 nM) revealed from Lineweaver–Burk plots. In silico docking studies with mushroom tyrosinase (PDB ID:2Y9X) predicted possible binding modes in the catalytic site for these active compounds. Ph9 displayed no PAINS (pan-assay interference compounds) alerts. Our results showed that compound Ph9 is a potential candidate for further development of tyrosinase inhibitors.

Melanoma of the central nervous system: A report of three cases

Melanomas within the Central Nervous System (CNS) are most commonly metastatic lesions, with primary melanomas comprising only 0.05-0.07% of all brain tumors. We report three cases of primary CNS melanoma. The patients were young adults. There were two females and one male. On preoperative investigations, two cases were misdiagnosed to be angiomas on Magnetic Resonance Imaging (MRI). The melanotic nature of the lesion was an intraoperative observation. Pathologic examination showed features of malignancy with invasion of tumor cells into the brain parenchyma. In two patients, presence of systemic lesions were ruled out after surgery by whole-body Positron Emission Tomography (PET) scan. These patients were subject to adjuvant radiotherapy, while one patient succumbed immediately post-surgery. Primary CNS melanomas are rare with no defined treatment protocols. Histopathology diagnosis is crucial to rule out pigmented mimics.

From Conventional Therapies to Immunotherapy: Melanoma Treatment in Review

Simple Summary

Here, we review the current state of knowledge in the field of cancer immunotherapy, focusing on the scientific rationale for the use of oncolytic viruses, checkpoint inhibitors and their combination to combat melanomas. Attention is also given to the immunological aspects of cancer therapy and the shift from conventional therapy towards immunotherapy. This review brings together information on how immunotherapy can be applied to support other cancer therapies in order to maximize the efficacy of melanoma treatment and improve clinical outcomes.

Abstract

In this review, we discuss the use of oncolytic viruses and checkpoint inhibitors in cancer immunotherapy in melanoma, with a particular focus on combinatory therapies. Oncolytic viruses are promising and novel anti-cancer agents, currently under investigation in many clinical trials both as monotherapy and in combination with other therapeutics. They have shown the ability to exhibit synergistic anticancer activity with checkpoint inhibitors, chemotherapy, radiotherapy. A coupling between oncolytic viruses and checkpoint inhibitors is a well-accepted strategy for future cancer therapies. However, eradicating advanced cancers and tailoring the immune response for complete tumor clearance is an ongoing problem. Despite current advances in cancer research, monotherapy has shown limited efficacy against solid tumors. Therefore, current improvements in virus targeting, genetic modification, enhanced immunogenicity, improved oncolytic properties and combination strategies have a potential to widen the applications of immuno-oncology (IO) in cancer treatment. Here, we summarize the strategy of combinatory therapy with an oncolytic vector to combat melanoma and highlight the need to optimize current practices and improve clinical outcomes.

Mining Database for the Clinical Significance and Prognostic Value of ESRP1 in Cutaneous Malignant Melanoma

BACKGROUND

Epithelial splicing regulatory protein 1 (ESRP1) has been described as an RNA-binding protein involved in cancer development. However, the expression and regulatory network of ESRP1 in cutaneous malignant melanoma (CMM) remain unclear.

METHODS

From the sequencing data of 103 CMM samples in The Cancer Genome Atlas database, the expression level of ESRP1 and its correlation with the clinicopathological characteristics were analyzed using the Oncomine 4.5, Gene Expression Profiling Interactive Analysis (GEPIA), and UALCAN tools, while LinkedOmics was used to identify differential gene expression with ESRP1 and to analyze Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Gene enrichment analysis examined target networks of kinases, miRNAs, and transcription factors. Finally, TIMER was used to analyze the relationship between ESRP1 and tumor immune cell infiltration.

RESULTS

We found that ESRP1 was lowly expressed in CMM tissues, and a low level of ESRP1 expression correlated with better overall survival. Expression of this gene was linked to functional networks involving the condensed chromosomes, epidermal development, and translation initiation. Functional network analysis suggested that ESRP1 regulated ribosome metabolism, drug metabolism, and chemical carcinogenesis via pathways involving several cancer-related kinases, miRNAs, and transcription factors. Furthermore, our results suggested that ESRP1 played an important role in regulating tumor-associated macrophage polarization, dendritic cell infiltration, Treg cells, and T cell exhaustion.

CONCLUSION

Our study demonstrates ESRP1 expression, prognostic value, and potential regulatory networks in CMM, thereby shedding light on the clinical significance of ESRP1, and provides a novel biomarker for determining prognosis and immune infiltration in CMM.

STAT3 transcription factor as target for anti-cancer therapy

STATs constitute a large family of transcription activators and transducers of signals that have an important role in many cell functions as regulation of proliferation and differentiation of the cell also regulation of apoptosis and angiogenesis. STAT3 as a member of that family, recently was discovered to have a vital role in progression of different types of cancers. The activation of STAT3 was observed to regulate multiple gene functions during cancer-like cell proliferation, differentiation, apoptosis, metastasis, inflammation, immunity, cell survival, and angiogenesis. The inhibition of STAT3 activation has been an important target for cancer therapy. Inhibitors of STAT3 have been used for a long time for treatment of many types of cancers like leukemia, melanoma, colon, and renal cancer. In this review article, we summarize and discuss different drugs inhibiting the action of STAT3 and used in treatment of different types of cancer.

Loss of Two-Pore Channel 2 (TPC2) Expression Increases the Metastatic Traits of Melanoma Cells by a Mechanism Involving the Hippo Signalling Pathway and Store-Operated Calcium Entry

Melanoma is one of the most aggressive and treatment-resistant human cancers. The two-pore channel 2 (TPC2) is located on late endosomes, lysosomes and melanosomes. Here, we characterized how TPC2 knockout (KO) affected human melanoma cells derived from a metastatic site. TPC2 KO increased these cells’ ability to invade the extracelullar matrix and was associated with the increased expression of mesenchymal markers ZEB-1, Vimentin and N-Cadherin, and the enhanced secretion of MMP9. TPC2 KO also activated genes regulated by YAP/TAZ, which are key regulators of tumourigenesis and metastasis. Expression levels of ORAI1, a component of store-operated Ca²⁺ entry (SOCE), and PKC-βII, part of the HIPPO pathway that negatively regulates YAP/TAZ activity, were reduced by TPC2 KO and RNA interference knockdown. We propose a cellular mechanism mediated by ORAI1/Ca²⁺/PKC-βII to explain these findings. Highlighting their potential clinical significance, patients with metastatic tumours showed a reduction in TPC2 expression. Our research indicates a novel role of TPC2 in melanoma. While TPC2 loss may not activate YAP/TAZ target genes in primary melanoma, in metastatic melanoma it could activate such genes and increase cancer aggressiveness. These findings aid the understanding of tumourigenesis mechanisms and could provide new diagnostic and treatment strategies for skin cancer and other metastatic cancers.

Deep tissue volumetric optoacoustic tracking of individual circulating tumor cells in an intracardially perfused mouse model

Widespread metastasis is the major cause of death from melanoma and other types of cancer. At present, the dynamic aspects of the metastatic cascade remain enigmatic. The feasibility to track circulating melanoma cells deep within living intact organisms can greatly impact our knowledge on tumor metastasis, but existing imaging approaches lack the sensitivity, spatio-temporal resolution or penetration depth to capture flowing tumor cells over large fields of view within optically-opaque biological tissues. Vast progress with the development of optoacoustic tomography technologies has recently enabled two- and three-dimensional imaging at unprecedented frame rates in the order of hundreds of Hertz, effectively mapping up to a million image voxels within a single volumetric snapshot. Herein, we employ volumetric optoacoustic tomography for real-time visualization of passage and trapping of individual B16 melanoma cells in the whole mouse brain. Detection of individual circulating melanoma cells was facilitated by substituting blood with an artificial cerebrospinal fluid that removes the strong absorption background in the optoacoustic images. The approach can provide new opportunities for studying trafficking and accumulation of metastatic melanoma cells in different organs.

Automatic diagnosis of melanoma using hyperspectral data and GoogLeNet

BACKGROUND

Melanoma is a type of superficial tumor. As advanced melanoma has a poor prognosis, early detection and therapy are essential to reduce melanoma-related deaths. To that end, there is a need to develop a quantitative method for diagnosing melanoma. This paper reports the development of such a diagnostic system using hyperspectral data (HSD) and a convolutional neural network, which is a type of machine learning.

MATERIALS AND METHODS

HSD were acquired using a hyperspectral imager, which is a type of spectrometer that can simultaneously capture information about wavelength and position. GoogLeNet pre-trained with Imagenet was used to model the convolutional neural network. As many CNNs (including GoogLeNet) have three input channels, the HSD (involving 84 channels) could not be input directly. For that reason, a "Mini Network" layer was added to reduce the number of channels from 84 to 3 just before the GoogLeNet input layer. In total, 619 lesions (including 278 melanoma lesions and 341 non-melanoma lesions) were used for training and evaluation of the network.

RESULTS AND CONCLUSION

The system was evaluated by 5-fold cross-validation, and the results indicate sensitivity, specificity, and accuracy of 69.1%, 75.7%, and 72.7% without data augmentation, 72.3%, 81.2%, and 77.2% with data augmentation, respectively. In future work, it is intended to improve the Mini Network and to increase the number of lesions.

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

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

Melanoma in the Eyes of Mechanobiology

Skin is the largest organ of the human body with several important functions that can be impaired by injury, genetic or chronic diseases. Among all skin diseases, melanoma is one of the most severe, which can lead to death, due to metastization. Mechanotransduction has a crucial role for motility, invasion, adhesion and metastization processes, since it deals with the response of cells to physical forces. Signaling pathways are important to understand how physical cues produced or mediated by the Extracellular Matrix (ECM), affect healthy and tumor cells. During these processes, several molecules in the nucleus and cytoplasm are activated. Melanocytes, keratinocytes, fibroblasts and the ECM, play a crucial role in melanoma formation. This manuscript will address the synergy among melanocytes, keratinocytes, fibroblasts cells and the ECM considering their mechanical contribution and relevance in this disease. Mechanical properties of melanoma cells can also be influenced by pigmentation, which can be associated with changes in stiffness. Mechanical changes can be related with the adhesion, migration, or invasiveness potential of melanoma cells promoting a high metastization capacity of this cancer. Mechanosensing, mechanotransduction, and mechanoresponse will be highlighted with respect to the motility, invasion, adhesion and metastization in melanoma cancer.

Opsin3 Downregulation Induces Apoptosis of Human Epidermal Melanocytes via Mitochondrial Pathway

G protein‐coupled receptors (GPCRs) are core switches connecting excellular survival or death signals with cellular signaling pathways in a context‐dependent manner. Opsin 3 (OPN3) belongs to the GPCR superfamily. However, whether OPN3 can control the survival or death of human melanocytes is not known. Here, we try to investigate the inherent function of OPN3 on the survival of melanocytes. Our results demonstrate that OPN3 knockdown by RNAi‐OPN3 in human epidermal melanocytes leads to cell apoptosis. The downregulation of OPN3 markedly reduces intracellular calcium levels and decreases phosphorylation of BAD. Attenuated BAD phosphorylation and elevated BAD protein level alter mitochondria membrane permeability, which trigger activation of BAX and inhibition of BCL‐2 and raf‐1. Activated BAX results in the release of cytochrome c and the loss of mitochondrial membrane potential. Cytochrome c complexes associate with caspase 9, forming a postmitochondrial apoptosome that activate effector caspases including caspase 3 and caspase 7. The release of apoptotic molecules eventually promotes the occurrence of apoptosis. In conclusion, we hereby are the first to prove that OPN3 is a key signal responsible for cell survival through a calcium‐dependent G protein‐coupled signaling and mitochondrial pathway.

Directed vertical cell migration via bifunctionalized nanomaterials in 3D step-gradient nanocomposite hydrogels

Step-gradient scaffolds promote healthy cell migration, while inhibit the migration of cancerous cells in the XZ plane of the ²GradNS.

Overexpression of RACK1 Predicts Poor Prognosis in Melanoma

Melanoma is a highly malignant skin cancer with limited treatment options, the mechanism of the occurrence and development of melanoma is still unclear till now. Receptor for activated C kinase 1 (RACK1) is a scaffolding protein that mediates multiple signaling pathways; it interconnects distinct signaling pathways to control essential cellular processes. RACK1 was reported as an oncogene in human tumorigenesis, but little is known about its role in melanoma. This study aimed to investigate the expression of RACK1 in patients with melanoma and to reveal its possible functions in melanoma cells. The expression profiles of RACK1 detected in tumor tissues from melanoma patients showed that RACK1 was higher in tumor tissues, and its expression level was well associated with the clinical progression of melanoma (TNM stage, P=0.009). Furthermore, RNA interfering (RNAi) knockdown of RACK1 could efficiently suppress the proliferation, migration and invasion of A375 and A875 cells and promote their apoptosis. Taken together, these results suggest that RACK1 may be a poor prognostic factor in human melanoma, and it may be a new therapeutic target for melanoma treatment.

Hydroxyl substituted benzoic acid/cinnamic acid derivatives: Tyrosinase inhibitory kinetics, anti-melanogenic activity and molecular docking studies

The inhibition of tyrosinase is an established strategy for treating hyperpigmentation. Our previous findings demonstrated that cinnamic acid and benzoic acid scaffolds can be effective tyrosinase inhibitors with low toxicity. The hydroxyl substituted benzoic and cinnamic acid moieties of these precursors were incorporated into new chemotypes that displayed in vitro inhibitory effect against mushroom tyrosinase. The most active compound, (2-(3-methoxyphenoxy)-2-oxoethyl (E)-3-(4-hydroxyphenyl) acrylate) 6c, inhibited tyrosinase with an IC₅₀ of 5.7 µM, while (2-(3-methoxyphenoxy)-2-oxoethyl 2, 4-dihydroxybenzoate) 4d had an IC₅₀ of 23.8 µM. In comparison, the positive control, kojic acid showed tyrosinase inhibition with an IC₅₀ = 16.7 µM. Analysis of enzyme kinetics revealed that 6c and 4d displayed noncompetitive reversible inhibition of the second tyrosinase enzymatic reaction with K_i values of 11 µM and 130 µM respectively. In silico docking studies with mushroom tyrosinase (PDB ID 2Y9X) predicted possible binding modes in the catalytic site for these active compounds. The phenolic para-hydroxy group of the most active compound 6c is predicted to interact with the catalytic site Cu⁺⁺ ion. The methoxy part of this compound is predicted to form a hydrogen bond with Arg 268. Compound 6c had no observable toxic effects on cell morphology or cell viability at the highest tested concentration of 91.4 µM. When dosed at 91.4 µM onto B16F10 melanoma cells in vitro6c showed anti-melanogenic effects equivalent to kojic acid at 880 µM. 6c displayed no PAINS (pan-assay interference compounds) alerts. Our results show that compound 6c is a more potent tyrosinase inhibitor than kojic acid and is a candidate for further development. Our exposition of the details of the interactions between 6c and the catalytic pocket of tyrosinase provides a basis for rational design of additional potent inhibitors of tyrosinase, built on the cinnamic acid scaffold.

Insights into Fibroblast Plasticity: Cellular Communication Network 2 Is Required for Activation of Cancer-Associated Fibroblasts in a Murine Model of Melanoma

Tumor stroma resembles a fibrotic microenvironment, being characterized by the presence of myofibroblast-like cancer-associated fibroblasts (CAFs). In wild-type mice injected with melanoma cells, we show that the stem cell transcription factor Sox2 is expressed by tumor cells and induced in CAFs derived from synthetic fibroblasts. These fibroblasts were labeled postnatally with green fluorescent protein using mice expressing a tamoxifen-dependent Cre recombinase under the control of a fibroblast-specific promoter/enhancer. Conversely, fibroblast activation was impaired in mice with a fibroblast-specific deletion of cellular communication network 2 (Ccn2), associated with reduced expression of α-smooth muscle actin and Sox2. Multipotent Sox2-expressing skin-derived precursor (SKP) spheroids were cultured from murine back skin. Using lineage tracing and flow cytometry, approximately 40% of SKPs were found to be derived from type I collagen-lineage cells and acquired multipotency in culture. Inhibition of mechanotransduction pathways prevented myofibroblast differentiation of SKPs and expression of Ccn2. In SKPs deleted for Ccn2, differentiation into a myofibroblast, but not an adipocyte or neuronal phenotype, was also impaired. In human melanoma, CCN2 expression was associated with a profibrotic integrin alpha (ITGA) 11-expressing subset of CAFs that negatively associated with survival. These results suggest that synthetic dermal fibroblasts are plastic, and that CCN2 is required for the differentiation of dermal progenitor cells into a myofibroblast/CAF phenotype and is, therefore, a therapeutic target in melanoma.

Dnmt3a is required for the tumor stemness of B16 melanoma cells

The relationship of carcinogenesis and DNA methyltransferases has attracted extensive attention in tumor research. We reported previously that inhibition of de novo DNA methyltransferase 3a (Dnmt3a) in murine B16 melanoma cells significantly suppressed tumor growth and metastasis in xenografted mouse model. Here, we further demonstrated that knockdown of Dnmt3a enhanced the proliferation in anchor-independent conditions of B16 cells, but severely disrupted its multipotent differentiation capacity in vitro. Furthermore, transforming growth factor β1, a key trigger in stem cell differentiation and tumor cell epithelial-mesenchymal transition (EMT), mainly induced apoptosis, but not EMT in Dnmt3a-deficient B16 cells. These data suggested that Dnmt3a is required for maintaining the tumor stemness of B16 cells and it assists B16 cells to escape from death during cell differentiation. Thus it is hypothesized that not only extraordinary self-renewal ability, but also the capacity of multipotent differentiation is necessary for the melanoma tumorigenesis. Inhibition of multipotent differentiation of tumor cells may shed light on the tumor treatment.

Differentiation of adipose-derived stem cells to functional CD105neg CD73low melanocyte precursors guided by defined culture condition

Background

The generation of functional human epidermal melanocytes (HEM) from stem cells provides an unprecedented source for cell-based therapy in vitiligo. Despite the important efforts exerted to obtain melanin-producing cells from stem cells, pre-clinical results still lack the safety and scalability characteristics essential for their translational application.

Methods

Here, we report a rapid and efficient protocol based on defined culture conditions capable of differentiating adult adipose-derived stem cells (ADSC) to scalable amounts of proliferative melanocyte precursors (PreMel) within 30 days. PreMel were characterized in vitro through qPCR, Western blot, flow cytometry, biochemical assays, and in vivo assays in immunocompromised mice (NOD.Cg-Prkdc^scid Il2rg^tm1Wjl/SzJ, or NSG).

Results

After 30 days of differentiation, the stem cell-derived PreMel were defined as CD105^neg CD73^low according to immunophenotypic changes in comparison with parental stem cell markers. In addition, expression of microphthalmia-associated transcription factor (MITF), active tyrosinase (TYR), and the terminal differentiation-involved premelanosome protein (PMEL) were detected. Furthermore, PreMel had the potential to synthesize melanin and package it into melanosomes both in vitro and in vivo in NSG mice skin.

Conclusions

This study proposes a rapid and scalable protocol for the generation of proliferative melanocyte precursors (PreMel) from ADSC. These PreMel display the essential functional characteristics of bona fide HEM, opening a new path for an autologous cellular therapy for vitiligo patients.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1364-0) contains supplementary material, which is available to authorized users.

Extraction, isolation and in vitro evaluation of affinisine from Tabernaemontana catharinensis in human melanoma cells

Plant compounds have been identified as new drug prototypes. In this line, this work aimed to isolate the indole alkaloid affinisine from Tabernaemontana catharinensis and test its antitumor activity. The alkaloid was isolated by silica gel open column chromatography from the ethanolic extract of the stem of T. catharinensis. Afterwards, this molecule was characterized by high-resolution mass spectrometry and nuclear magnetic resonance. In the next step, the cytotoxicity of the compound was tested against human melanoma cell lines (A375, WM1366 and SK-MEL-28) and a normal skin cell line (CCD-1059Sk) using a MTT (3-4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Cells treated with affinisine were evaluated by flow cytometry to analyze apoptosis and the induction of cell cycle arrest, to evaluate the dead mechanism. The metabolite was isolated in a 0.2% yield relative to the extract. Cytotoxic activity of the molecule was observed at 48 h, resulting in considerable growth inhibition rates in melanoma cells, especially in WM1366, which had the lowest IC₅₀ (32.86 ± 2.54 µg/mL). The apoptosis rate was lower in A375 (56.66 and 86.71% with 57 and 65 µg/mL, respectively). Moreover, affinisine was able to significantly induce cell cycle arrest in different phases in the A375 and WM1366 cell lines. However, in SK-MEL-28 cells, cycle arrest was not observed. In summary, this compound significantly decreased the viability of tumor cells in a dose- and time-dependent manner for all evaluated lineages, reduced cell viability by the apoptosis mechanism and presented prominent activities of cell cycle arrest. In this way, the use of antineoplastic agents is among the most widely used therapeutic measures for the control and treatment of cancer. Affinisine is a promising prototype in the search for new drugs to treat cancer.

Characteristics of Brazilian melanomas: real-world results before and after the introduction of new therapies

Objective

This study is a characterization of the treatment patterns and outcomes of a Brazilian melanoma cohort collected of 1848 patients enrolled between 1996 and 2015.

Results

The superficial spreading subtype (35.1%) was the most prevalent, and the favoured anatomical location was the trunk (32.8%). The most common clinical stage was I (27.6%). The most frequent initial treatment was surgery (84.7%). Sentinel node biopsy was positive in 23.3% of cases. Chemotherapy was used to treat 298 patients (16.1%), immunotherapy for 67 (3.6%) and targeted therapy for 19 (1.0%). Distant recurrence was commonly observed (22.5%) and the mutation status of the BRAF gene was verified in 132 cases, with 42.4% positivity in this subset of patients. The melanoma specific actuarial 5-year survival for the cohort was 68.8%. There was a higher 5-year survival observed in metastatic melanoma patients who received immunotherapy and/or targeted therapy (34.2%) compared patients treated with just chemotherapy (20.0%). The survival analysis showed that sex, age, Breslow, clinical stage and distant recurrence were significant prognostic factors. This study provides a real-world description of how the introduction of new therapies such as immunotherapy and BRAF inhibitors is changing treatment strategies for melanoma in developing countries.

Electronic supplementary material

The online version of this article (10.1186/s13104-019-4336-7) contains supplementary material, which is available to authorized users.