Melanoma Cell Proliferation Research Articles

CRISPR-Cas9 screening identified novel subtypes of cutaneous melanoma based on essential cancer genes.

Our primary objective was to identify genes critical for cutaneous melanoma (CM) and related typing, based on essential genes, to generate novel insights for clinical management and immunotherapy of patients with CM. We analyzed RNA sequencing (RNA-seq) data from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx), and sequencing data of 29 CM cell line from Cancer Cell Line Encyclopedia (CCLE) databases. Combined with DepMap database, 406 CM essential cancer genes were finally obtained. Based on the expression of essential genes in cancer, the patients included in TCGA and Gene Expression Omnibus (GEO) databases were divided into three different molecular subtypes (C1, C2, and C3) by the NMF algorithm. Data analysis from TCGA and GEO datasets revealed that subtype C3 had the poorest prognosis, while subtype C1 exhibited the best prognosis. Combined with the CIBERSORT, ESTIMATE and ssGSEA algorithm, patients with different molecular subtypes can be divided into two immune subtypes (hot and cold). We found that subtype C1 was characterized by hot tumors, in contrast to subtypes C2 and C3, which were characterized by cold tumors. Then, we used univariate Cox regression, LASSO, and multifactor Cox regression analysis to select risk genes and constructed a prognostic model based on eight genes: RABIF, CDCA8, FOXM1, SPRR2E, AIP, CAP1, CTSW, and IFITM3. All patients were divided into two risk subtypes (high and low ) according to the median of risk scores. We found that most hot tumor subtypes were found in the low-risk subtypes and most patients with this subtype survived for longer. Ultimately, we selected RABIF, which exhibits the highest risk coefficient, for histological and cytological verification. The results showed that RABIF was overexpressed in melanoma. Inhibition of RABIF expression could suppress the proliferation and invasion of melanoma cells and promote the apoptosis of melanoma cells. In conclusion, we used CRISPR-Cas9 screening to verify the association between molecular subtypes (C1, C2, and C3), immune subtypes (hot and cold), and risk subtypes (high and low) in patients with CM, particularly in distinguishing survival and prognosis. These findings can be used to guide clinical management and immunotherapy of patients with CM.

Swimming upregulates APOL3 through regulating macrophage polarization to inhibit glycolysis and the development of melanoma.

This study investigated the role of swimming exercise in regulating melanoma tumour growth and glycolysis in cancer cells, the specific mechanism involved was also studied. In our study, a murine melanoma tumour model was established to assess the impact of swimming on tumour growth. The mRNA and protein expressions were assessed using qRT-PCR, western blot, and IHC. The metabolic behavior of melanoma cells was examined through lactic acid level measurements and glucose consumption assessments. CCK-8 and colony formation assays were used to detect cell viability and proliferation. ELISA was employed to determine the levels of cytokines secreted by macrophages. The interaction between APOL3 and STAT3 was analyzed by dual luciferase reporter gene and ChIP assays. Our results demonstrated that swimming exercise suppressed melanoma growth in mice by suppressing glycolysis, which might be related to APOL3 upregulation. In addition, downregulation of APOL3 in melanoma was associated with poor prognosis, and APOL3 overexpression markedly suppressed melanoma cell proliferation by reducing glucose uptake and lactate production in vitro. Mechanistically, STAT3 directly down-regulated APOL3 transcription. Swimming upregulated APOL3 by inactivating the IL-6R-STAT3 signaling axis in melanoma cells by inhibiting the secretion of IL-6 by M2 macrophages. As expected, IL-6 secreted by M2 macrophages promoted glycolysis in melanoma cells by reducing APOL3 expression. In summary, swimming inactivated the IL-6R/STAT3 signaling axis in melanoma cells by inhibiting the secretion of IL-6 by M2 macrophages, which could suppress the growth of melanoma in the body by upregulating APOL3 to inhibit glycolysis.

CTNND2 gene expression in melanoma tissues and its effects on the malignant biological functions of melanoma cells.

The catenin delta 2 (CTNND2) gene has been implicated in the progression of various cancers, but its specific role in melanoma has not yet been thoroughly investigated. This study sought to explore the expression and biological function of CTNND2 in malignant melanoma tissues to identify new targets or biomarkers for melanoma diagnosis and treatment. Immunohistochemistry was used to examine the levels of CTNND2 in melanoma and adjacent non-tumor tissues. A Western blot analysis was performed to quantify the expression levels of CTNND2 in human immortalized keratinocytes and melanoma cell lines. The Cell Counting Kit-8 (CCK-8) assay, plate colony formation assay, cell adhesion assay, scratch test, and Transwell assay were used to assess the effects of CTNND2 knockdown on the proliferation, adhesion, migration, and invasion of melanoma cells. The Harmonizome database was used to research the biological processes (BPs) involved in CTNND2. In the melanoma tissues, CTNND2 expression was substantially upregulated and its levels were closely linked with the pathological features of patients. The CTNND2 levels were notably more increased in the melanoma cell lines than the immortalized keratinocytes. The suppression of the CTNND2 gene substantially impeded the capacity of the melanoma cells to proliferate, migrate, and invade, and also significantly decreased their potential to attach to collagen I and IV, and fibronectin. The Harmonizome database results revealed a strong correlation between the BPs controlled by CTNND2 and the focal adhesion signaling pathway of the cells. The inhibition of the CTNND2 gene in melanoma cells resulted in a significant decrease in the phosphorylation of focal adhesion kinase (FAK) and the production of paxillin protein. In the melanoma cells, the reduction of CTNND2 did not have a significant effect on the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway. However, it did considerably prevent the activation of mitogen-activated extracellular signal-regulated kinase 1/2 (MEK1/2) and its downstream molecule extracellular signal-regulated protein kinase 1/2 (ERK1/2). The expression of the CTNND2 gene is increased in melanoma tissues, which enhances the ability of melanoma cells to proliferate both in vivo and in vitro. Additionally, the CTNND2 gene is crucial in controlling the adhesion process of melanoma cells. This mechanism is associated with the regulation of the FAK and MEK1/2/ERK1/2 signaling pathways. Based on our findings, CTNND2 could be used as an oncogene target for melanoma and a new treatment target or diagnostic biomarker.

ATF3 regulates CDC42 transcription and influences cytoskeleton remodeling, thus inhibiting the proliferation, migration and invasion of malignant skin melanoma cells.

Cutaneous malignant melanoma (CMM) is one of the most aggressive and lethal types of skin cancer. Cytoskeletal remodeling is a key factor in the progression of CMM. Previous research has shown that activating transcription factor 3 (ATF3) inhibits metastasis in bladder cancer by regulating actin cytoskeleton remodeling through gelsolin. However, whether ATF3 plays a similar role in cytoskeletal remodeling in CMM cells remains unknown. Various gene and protein expression analyses were performed using techniques such as reverse transcription quantitative PCR, western blot, immunofluorescent staining, and immunohistochemical staining. CMM viability, migration, and invasion were examined through cell counting kit-8 and transwell assays. The interactions between cell division cycle 42 (CDC42) and ATF3 were investigated using chromatin immunoprecipitation and dual-luciferase reporter assays. CDC42 was upregulated in CMM tissues and cells. Cytoskeletal remodeling of CMM cells, as well as CMM cell proliferation, migration, and invasion, were inhibited by CDC42 or ATF3. ATF3 targeted the CDC42 promoter region to regulate its transcriptional activity. ATF3 suppresses cytoskeletal remodeling in CMM cells, thereby inhibiting CMM progression and metastasis through CDC42. This research may provide a foundation for using ATF3 as a therapeutic target for CMM.

Metformin regulates the proliferation and motility of melanoma cells by modulating the LINC00094/miR-1270 axis.

Melanoma is an aggressive tumor with a high mortality rate. Metformin, a commonly prescribed diabetes medication, has shown promise in cancer prevention and treatment. Long noncoding RNAs (lncRNAs) are non-protein-coding RNA molecules that play a key role in tumor development by interacting with cellular chromatins. Despite the benefits of metformin, the anticancer mechanism underlying its effect on the regulation of lncRNAs in melanoma remains unclear. We investigated the lncRNA profiles of human melanoma cells with and without metformin treatment using a next-generation sequencing approach (NGS). Utilizing public databases, we analyzed the expression levels and clinical impacts of LINC00094 and miR-1270 in melanoma. The expression levels of LINC00094 and miR-1270 were verified in human cell lines and clinical samples by real-time PCR and in situ hybridization. The biological roles of LINC00094 and miR-1270 in cell growth, proliferation, cell cycle, apoptosis, and motility were studied using in vitro assays. We identify a novel long noncoding RNA, namely LINC00094, whose expression considerably decreased in melanoma cells after metformin treatment. In situ hybridization analysis revealed substantially higher expression of LINC00094 in cutaneous melanoma tissue compared with adjacent normal epidermis and normal control tissues (P < 0.001). In nondiabetic patients with melanoma, the overall survival of high LINC00094 expression group was shorter than the low LINC00094 expression group with borderline statistical significance (log-rank test, P = 0.057). Coexpression analysis of LINC00094 indicated its involvement in the mitochondrial respiratory pathway, with its knockdown suppressing genes associated with mitochondrial oxidative phosphorylation, glycolysis, antioxidant production, and metabolite levels. Functional analysis revealed that silencing-LINC00094 inhibited the proliferation, colony formation, invasion, and migration of melanoma cells. Cell cycle analysis following LINC00094 knockdown revealed G1 phase arrest with reduced cell cycle protein expression. Combined TargetScan and reporter assays revealed a direct link between miR-1270 and LINC00094. Ectopic miR-1270 expression inhibited melanoma cell growth and motility while inducing apoptosis. Finally, through in silico analysis, we identified two miR-1270 target genes, CD276 and centromere protein M (CENPM), which may be involved in the biological functions of LINC00094. Overall, LINC00094 expression may regulate melanoma cell growth and motility by modulating the expression of miR-1270, and targeting genes of CD276 and CENPM indicating its therapeutic potential in melanoma treatment.

Abstract A042: Desmosome mutations in the microenvironment regulate melanoma proliferation

Abstract Desmosomes are transmembrane protein complexes critical for cell-cell adhesion in epithelial tissues and other cell types. In skin cancers like melanoma, epithelial cells called keratinocytes are the predominant cells in the primary melanoma microenvironment, yet it remains largely unknown whether this cell type is subject to genetic alterations during melanoma development and its role in early melanoma progression. In this study, using an integrative analysis of tumor mutations and protein biophysical interactions, we identify a high frequency of genetic alterations in desmosome-related genes in human cancers, with the highest occurrences in cutaneous melanoma. Notably, over 70% of cutaneous melanoma cases exhibit mutations in desmosome genes and desmosome gene mutations are associated with lowered expression of the desmosome complex in melanoma. Using spatial transcriptomics and immunohistochemistry analyses, we find that the decrease in desmosome gene expression predominantly occurs in keratinocytes within the tumor microenvironment rather than in the melanoma cells themselves. To study the functional significance of this alteration in melanoma development, we used a human melanoma/keratinocyte co-culture system using primary melanoma cell lines. Our studies show that knockdown of desmosome genes in keratinocytes markedly increased proliferation of adjacent melanoma cells in melanoma/keratinocyte co-cultures. Additionally, melanoma cell proliferation is enhanced when exposed to media preconditioned by desmosome-deficient keratinocytes. These observations suggest that the gradual accumulation of mutations in desmosome genes within neighboring keratinocytes may create a conducive environment that primes melanoma cells for neoplastic transformation. This study underscores the critical role of genetic alterations in the tumor microenvironment in melanoma progression and highlights the potential for targeting desmosome-related pathways in therapeutic strategies against melanoma. Citation Format: Mohita Tagore. Desmosome mutations in the microenvironment regulate melanoma proliferation [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr A042.

Treatment of Melanoma Cells with Chloroquine and Everolimus Activates the Apoptosis Process and Alters Lipid Redistribution.

The balance between apoptosis and autophagy plays a key role in cancer biology and treatment strategies. The aim of this study was to assess the effect of the mTOR kinase inhibitor everolimus and chloroquine on the regulation of proliferation, caspase-3 activation, and apoptosis in melanoma cells. We studied the activity of caspase-3 and the levels of caspase-3 and -9 using the Western blot technique. Cellular apoptosis was examined using a DNA fragmentation assay, and changes in the cell nucleus and cytoskeleton were examined using fluorescence microscopy DAPI, OA/IP. We also studied the rearrangement of lipid structures using fluorescent dyes: Nile Red and Nile Blue. A low nanomolar concentration of the mTOR kinase inhibitor everolimus in combination with chloroquine activated the apoptosis process and decreased cell proliferation. These changes were accompanied by an obvious change in cell morphology and rearrangement of lipid structures. Alterations in lipid redistribution accompanying the process of apoptosis and autophagy are among the first to occur in the cell and can be easily monitored in in vitro studies. The combination of mTOR inhibitors and chloroquine represents a promising area of research in cancer therapy. It has the potential to enhance treatment efficacy through complementary mechanisms.

TIPE2 inhibits melanoma progression through MEK/ERK signaling

Recent studies have uncovered that TIPE2 is involved in the development of cancer. However, less research has been conducted on the role of TIPE2 in melanoma. Our study aims to elucidate the mechanism of action of TIPE2 in the development of melanoma. We examined TIPE2 expression in paracarcinoma tissue and melanoma tissues and found that TIPE2 expression was downregulated in melanoma tissue compared with paracarcinoma tissue. Overexpression of TIPE2 significantly inhibited the proliferation of melanoma cells in vitro and even inhibited tumor formation in vivo. The CCK8 assay results indicated that TIPE2 overexpression suppressed the proliferation of melanoma cells. The colony-forming ability and wound healing ability of TIPE2-overexpressing melanoma cells were significantly reduced compared with those of control cells. Moreover, immunohistochemistry experiments using a nude mouse tumor model showed consistent results. TIPE2 inhibited the phosphorylation of MEK and ERK. In summary, TIPE2 suppresses the proliferation and migration of melanoma cells by affecting proliferation-related factors and possibly by regulating the MEK/ERK pathway. TIPE2 could be used to inhibit melanoma growth and is a potential drug target for future drug development.

Effect of gedunin on cell proliferation and apoptosis in skin melanoma cells A431 via the PI3K/JNK signaling pathway.

Melanoma is an aggressive skin malignancy with rapid metastasis and high morbidity. Gedunin (GN) is a tetranortriterpenoid belonging to the Meliaceae family, described for its anticancer, antiproliferative and apoptotic properties. In the present study, we investigated the effect of GN on A431 melanoma cell proliferation and apoptosis. The inflammatory proteins (tumor necrosis factor alpha (TNF-α), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), cycloxygenase 2 (COX-2), inducible nitric oxide synthase (iNOS), and interleukin 6 (IL-6)) apoptosis-related proteins, such as Bax, Bcl-2 and caspase-3, and alterations in the PI3K/JNK and p38 pathways in A431 cells after GN treatment were examined. The cytotoxicity assay and cell apoptosis of GN activity on A431 cells were assessed using MTT assay, acridine orange/ethidium bromide (AO/EB), DAPI (4',6-diamidino-2-phenylindole), propidium iodide (PI), enzyme-linked immunosorbent assay (ELISA), reverse transcription polymerase chain reaction (RT-PCR) and western blot analyses. The findings demonstrated that GN (10 and 15 μM/mL) inhibits the growth of melanoma cells, triggers apoptosis by enhancing Bax and caspase, and reduces Bcl-2, cyclin-D1, c-myc, and survivin in a concentration-reliant manner. Additionally, GN attenuated the protein expression of inflammatory proteins (TNF-α, NF-κB, COX-2, iNOS, and IL-6) and the cell proliferative PI3K/JNK/p38 signaling pathway. Due to the imbalance in the Bax/Bcl-2 ratio, apoptosis is promoted, and the caspase cascade and Cyt-c are activated. This led us to conclude that GN treatment inhibited Bcl-2, cyclin-D1, c-myc, and survivin activity through the TNF-α/NF-κB and PI3K/JNK/p38 signaling pathways, further preventing the proliferation and stimulation of apoptosis, which contributes to growth arrest in melanoma cells. Gedunin has been shown to promote melanoma cell death in vitro, suggesting that it could be used as a future treatment for malignant melanoma. Our findings suggested that GN might be applied as a preventative measure in the management of skin melanoma cells.

MCM4 Promotes the Progression of Malignant Melanoma by Activating the PI3K/AKT Pathway.

This study aims to elucidate the role of minichromosome maintenance protein 4 (MCM4) in malignant melanoma (MM) and explore the underlying mechanism. Initially, data from The Cancer Genome Atlas (TCGA) database and the Molecular Signature Database (MSigDB) were used to investigate the biological impact of MCM4 on MM. Further, a prognostic model using Cox regression analysis was developed to predict the overall survival (OS) rate in the MM patients. The effects of MCM4 on the proliferation, migration, and invasion abilities of MM (B16F0 and A375) cells were demonstrated using the CCK-8, colony formation, EDU, wound scratch, and Transwell assays. In subcutaneous tumor models in C57BL/6 mice invivo, the expression levels of MCM4 in MM cells and tumors were detected using Western blot and immunofluorescence approaches. The bioinformatics analysis indicated that MCM4 was expressed higher in MM tissues than in the normal tissues (p < 0.05). The established OS prediction model could significantly contribute to devising follow-up strategies and treating MM patients. MCM4 knockdown resulted in reduced proliferation, migration, and invasion abilities of MM cells, which were reversed by MCM4 overexpression (p < 0.05). Moreover, MCM4 could activate the phosphatidylinositol 3'-kinase (PI3K)/AKT pathway in MM cells. The PI3K inhibitor (LY294002) could reverse the effects of MCM4 on MM cells. MCM4 could substantially prompt the tumor growth of MM in mice through the PI3K/AKT pathway invivo. In summary, MCM4 prompted the development and metastasis of MM by activating the PI3K/AKT pathway.

PHGDH Induction by MAPK is Essential for Melanoma Formation and Creates an Actionable Metabolic Vulnerability.

Overexpression of PHGDH, the rate-limiting enzyme in the serine synthesis pathway, promotes melanomagenesis, melanoma cell proliferation, and survival of metastases in serine-low environments such as the brain. Here, we found that PHGDH is universally increased in melanoma cells and required for melanomagenesis. While PHGDH amplification explained PHGDH overexpression in a subset of melanomas, oncogenic BRAFV600E also promoted PHGDH transcription through mTORC1-mediated translation of ATF4. Importantly, depletion of PHGDH in genetic mouse melanoma models blocked tumor formation. In addition to BRAFV600E-mediated upregulation, PHGDH was further induced by exogenous serine restriction. Surprisingly, BRAFV600E inhibition diminished serine restriction-mediated PHGDH expression by preventing ATF4 induction. Consequently, melanoma cells could be specifically starved of serine by combining BRAFV600E inhibition with exogenous serine restriction, which promoted cell death in vitro and attenuated melanoma growth in vivo. In summary, this study identified that PHGDH is essential for melanomagenesis and regulated by BRAFV600E, revealing a targetable vulnerability in BRAFV600E-mutant melanoma.

Lnc NEAT1 facilitates the progression of melanoma by targeting the miR-152-3p/CDK6 axis: An observational study.

Long noncoding (Lnc) RNAs are novel regulators in melanoma. Lnc nuclear enriched autosomal transcript 1 (NEAT1) was reportedly upregulated in melanoma; however, the functional roles and mechanisms of Lnc NEAT1 need further investigation. Therefore, we used quantitative real-time PCR to determine the mRNA levels of Lnc NEAT1, miR-152-3p, and cyclin-dependent protein kinase 6 (CDK6). The protein level of CDK6 was determined by Western blot. Cell counting kit 8 and colony formation assays were used to assess cell proliferation. Cell migration was measured by wound healing and Transwell assays. Direct binding of the indicated molecules was verified by an RNA-binding protein immunoprecipitation assay and a dual luciferase reporter assay. The results revealed that Lnc NEAT1 and CDK6 were elevated, while miR-152-3p was downregulated in melanoma. Furthermore, Lnc NEAT1 was positively correlated with CDK6 expression and negatively correlated with miR-152-3p level. Furthermore, Lnc NEAT1 facilitated proliferation, migration, and invasion of melanoma cells. The underlying mechanism is that Lnc NEAT1 serves as a sponge for miR-152-3p to suppress the inhibitory effect of miR-152-3p on CDK6. Furthermore, the miR-152-3p/ CDK6 axis was implicated in the progression of melanoma accelerated by Lnc NEAT1. Taken together, Lnc NEAT1 may promote melanoma development by serving as an endogenous sponge of miR-152-3p, increasing CDK6 expression, and identifying a new target for the treatment of melanoma.

DTL promotes the growth and migration of melanoma cells through the ERK/E2F1/BUB1 axis

Melanoma is the most dangerous form of skin cancer. Hence, a better understanding of molecular mechanisms in melanoma pathogenesis is urgently needed, which provides a new insight into the therapy of melanoma. DTL gene is screened out in melanoma pathogenesis by integrated bioinformatics analysis, and its expression is validated in the tissue and cell samples of melanoma. Forced DTL expression facilitates the proliferation, invasion, migration and EMT of melanoma cells, while DTL knockdown suppresses the biological behavior of melanoma cells. In addition, DTL promotes the malignancy of melanoma in vivo. Mechanistically, BUB1 is the crucial downstream target of DTL. Reduced DTL expression suppresses BUB1 expression, while enhanced DTL expression induces BUB1 upregulation. Rescue experiments showed that growing and migrating of melanoma cells induced by DTL are partially impaired by BUB1 inhibition. In addition, the expression of phosphorylated ERK (p-ERK) and the downstream transcription factor E2F1 are reduced when DTL expression is blocked. Meanwhile, BUB1 levels are decreased when the expression of p-ERK or E2F1 is repressed. Notably, the growth and migration of melanoma cells by inhibition of ERK and knockdown of E2F1 was rescued by overexpressing BUB1. DTL gene may be a prognosis marker and represent a unique potential target for melanoma patients. DTL supports the biologically malignant activity of melanoma cells via the ERK/E2F1/BUB1 axis.

Tubulin-Targeted Therapy in Melanoma Increases the Cell Migration Potential by Activation of the Actomyosin Cytoskeleton─An In Vitro Study.

One of the most dangerous aspects of cancers is their ability to metastasize, which is the leading cause of death. Hence, it holds significance to develop therapies targeting the eradication of cancer cells in parallel, inhibiting metastases in cells surviving the applied therapy. Here, we focused on two melanoma cell lines─WM35 and WM266-4─representing the less and more invasive melanomas. We investigated the mechanisms of cellular processes regulating the activation of actomyosin as an effect of colchicine treatment. Additionally, we investigated the biophysical aspects of supplement therapy using Rho-associated protein kinase (ROCK) inhibitor (Y-27632) and myosin II inhibitor ((-)-blebbistatin), focusing on the microtubules and actin filaments. We analyzed their effect on the proliferation, migration, and invasiveness of melanoma cells, supported by studies on cytoskeletal architecture using confocal fluorescence microscopy and nanomechanics using atomic force microscopy (AFM) and microconstriction channels. Our results showed that colchicine inhibits the migration of most melanoma cells, while for a small cell population, it paradoxically increases their migration and invasiveness. These changes are also accompanied by the formation of stress fibers, compensating for the loss of microtubules. Simultaneous administration of selected agents led to the inhibition of this compensatory effect. Collectively, our results highlighted that colchicine led to actomyosin activation and increased the level of cancer cell invasiveness. We emphasized that a cellular pathway of Rho-ROCK-dependent actomyosin contraction is responsible for the increased invasive potential of melanoma cells in tubulin-targeted therapy.

DNA-Binding Protein A Is Actively Secreted in a Calcium-and Inflammasome-Dependent Manner and Negatively Influences Tubular Cell Survival.

DNA-binding protein A (DbpA) belongs to the Y-box family of cold shock domain (CSD) proteins that bind RNA/DNA and exert intracellular functions in cell stress, proliferation, and differentiation. Given the pattern of DbpA staining in inflammatory glomerular diseases, without adherence to cell boundaries, we hypothesized extracellular protein occurrence and specific functions. Lipopolysaccharide and ionomycin induce DbpA expression and secretion from melanoma and mesangial cells. Unlike its homologue Y-box-binding protein 1 (YB-1), DbpA secretion requires inflammasome activation, as secretion is blocked upon the addition of a NOD-like receptor protein-3 (NLRP3) inhibitor. The addition of recombinant DbpA enhances melanoma cell proliferation, migration, and competes with tumor necrosis factor (TNF) binding to its receptor (TNFR1). In TNF-induced cell death assays, rDbpA initially blocks TNF-induced apoptosis, whereas at later time points (>24 h), cells are more prone to die. Given that CSD proteins YB-1 and DbpA fulfill the criteria of alarmins, we propose that their release signals an inherent danger to the host. Some data hint at an extracellular complex formation at a ratio of 10:1 (DbpA:YB-1) of both proteins.

Anticancer Activity of Vitamin D, Lumisterol and Selected Derivatives against Human Malignant Melanoma Cell Lines.

Despite the recent development of improved methods of treating melanoma such as targeted therapy, immunotherapy or combined treatment, the number of new cases worldwide is increasing. It is well known that active metabolites of vitamin D3 and lumisterol (L3) exert photoprotective and antiproliferative effects on the skin, while UV radiation is a major environmental risk factor for melanoma. Thus, many natural metabolites and synthetic analogs of steroidal and secosteroidal molecules have been tested on various cancer cells and in animal models. In this study, we tested the anti-melanoma properties of several natural derivatives of vitamin D3 and L3 in comparison to 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). A significant decrease in melanoma cell proliferation and cell mobility was observed for selected derivatives, with (25R)-27-hydroxyL3 showing the highest potency (lowest IC50) in A375 cells but lower potency in SK-MEL-28 cells, whereas the parent L3 failed to inhibit proliferation. The efficacy (% inhibition) by 1,24,25(OH)3D3 and 1,25(OH)2D3 were similar in both cell types. 1,25(OH)2D3 showed higher potency than 1,24,25(OH)3D3 in SK-MEL-28 cells, but lower potency in A375 cells for the inhibition of proliferation. As for 1,25(OH)2D3, but not the other derivatives tested, treatment of melanoma cells with 1,24,25(OH)3D3 markedly increased the expression of CYP24A1, enhanced translocation of the vitamin D receptor (VDR) from the cytoplasm to the nucleus and also decreased the expression of the proliferation marker Ki67. The effects of the other compounds tested were weaker and occurred only under certain conditions. Our data indicate that 1,24,25(OH)3D3, which has undergone the first step in 1,25(OH)2D3 inactivation by being hydroxylated at C24, still shows anti-melanoma properties, displaying higher potency than 1,25(OH)2D3 in SK-MEL-28 cells. Furthermore, hydroxylation increases the potency of some of the lumisterol hydroxy-derivatives, as in contrast to L3, (25R)-27(OH)L3 effectively inhibits proliferation and migration of the human malignant melanoma cell line A375.

NOD2 reduces the chemoresistance of melanoma by inhibiting the TYMS/PLK1 signaling axis

AbstractNucleotide-binding oligomerization domain 2 (NOD2) is an immune sensor crucial for eliciting the innate immune responses. Nevertheless, discrepancies exist regarding the effect of NOD2 on different types of cancer. This study aimed to investigate these function of NOD2 in melanoma and its underlying mechanisms. We have validated the tumor suppressor effect of NOD2 in melanoma. NOD2 inhibited the proliferation of melanoma cells, hindering their migration and invasion while promoting the onset of apoptosis. Our study showed that NOD2 expression is closely related to pyrimidine and folate metabolism. NOD2 inhibits thymidylate synthase (TYMS) expression by promoting K48-type ubiquitination modification of TYMS, thereby decreasing the resistance of melanoma cells to 5-fluorouracil (5-FU) and capecitabine (CAP). TYMS was identified to form a complex with Polo-like Kinase 1 (PLK1) and activate the PLK1 signaling pathway. Furthermore, we revealed that the combination of the PLK1 inhibitor volasertib (BI6727) with 5-FU or CAP had a synergistic effect repressing the proliferation, migration, and autophagy of melanoma cells. Overall, our research highlights the protective role of NOD2 in melanoma and suggests that targeting NOD2 and the TYMS/PLK1 signaling axis is a high-profile therapy that could be a prospect for melanoma treatment.

Repurposing of Antidiarrheal Loperamide for Treating Melanoma by Inducing Cell Apoptosis and Cell Metastasis Suppression In vitro and In vivo.

Melanoma is the most common skin tumor worldwide and still lacks effective therapeutic agents in clinical practice. Repurposing of existing drugs for clinical tumor treatment is an attractive and effective strategy. Loperamide is a commonly used anti-diarrheal drug with excellent safety profiles. However, the affection and mechanism of loperamide in melanoma remain unknown. Herein, the potential anti-melanoma effects and mechanism of loperamide were investigated in vitro and in vivo. In the present study, we demonstrated that loperamide possessed a strong inhibition in cell viability and proliferation in melanoma using MTT, colony formation and EUD incorporation assays. Meanwhile, xenograft tumor models were established to investigate the anti-melanoma activity of loperamide in vivo. Moreover, the effects of loperamide on apoptosis in melanoma cells and potential mechanisms were explored by Annexin V-FITC apoptosis detection, cell cycle, mitochondrial membrane potential assay, reactive oxygen species level detection, and apoptosis-correlation proteins analysis. Furthermore, loperamide-suppressed melanoma metastasis was studied by migration and invasion assays. What's more, immunohistochemical and immunofluorescence staining assays were applied to demonstrate the mechanism of loperamide against melanoma in vivo. Finally, we performed the analysis of routine blood and blood biochemical, as well as hematoxylin- eosin (H&E) staining, in order to investigate the safety properties of loperamide. Loperamide could observably inhibit melanoma cell proliferation in vitro and in vivo. Meanwhile, loperamide induced melanoma cell apoptosis by accumulation of the sub-G1 cells population, enhancement of reactive oxygen species level, depletion of mitochondrial membrane potential, and apoptosis-related protein activation in vitro. Of note, apoptosis-inducing effects were also observed in vivo. Subsequently, loperamide markedly restrained melanoma cell migration and invasion in vitro and in vivo. Ultimately, loperamide was witnessed to have an amicable safety profile. These findings suggested that repurposing of loperamide might have great potential as a novel and safe alternative strategy to cure melanoma via inhibiting proliferation, inducing apoptosis and cell cycle arrest, and suppressing migration and invasion.

Inhibitory Effect of Tanshinone IIA Extracted from Radix Salviae miltiorrhizae on Melanoma B16F10 Cells

In this study, we investigate the inhibitory effects of Tanshinone IIA on the proliferation and migration of B16F10 melanoma cells and its potential mechanism of action. We cultured B16F10 melanoma cells in vitro and treated them with varying concentrations of tanshinone IIA. The inhibitory effect of tanshinone IIA on B16F10 cells was assessed using the CCK-8 assay, employing methyl thiazolyl tetrazolium. Melanin content was determined by the NaOH cleavage method, while expression levels of melanin-related proteins were analyzed by Western blotting, and migration-related proteins were quantified using ELISA. When the concentration of Tanshinone IIA reached 20 and 40 μg/mL, there was a decrease in the survival rate of B16F10 melanoma cells. The proliferation inhibition rate of B16F10 melanoma cells gradually increased with the duration of drug action and the concentration of Tanshinone IIA. After 48 hours, there was an increase in melanin content. A comparison of melanin synthesis at the three concentrations yielded an F value of 61.820 and P &lt;0.001. The relative expression levels of TYR, TRP-1, TRP-2, and MITF increased when treated with different concentrations of Tanshinone IIA (P &lt; 0.05). MMP-2 and MMP-9 were downregulated when the concentration of Tanshinone IIA was at 40 and 80 μg/mL respectively (P &lt;0.05). In conclusion, our study demonstrated the inhibitory effects of Tanshinone IIA on growth, proliferation, migration, and melanin synthesis in B16F10 melanoma cells. However, further research is needed to elucidate the specific signal transduction pathway activated by Tanshinone IIA.

A new cannabigerol derivative, LE-127/2, induces autophagy mediated cell death in human cutaneous melanoma cells

Despite the targeted- and immunotherapies used in the past decade, survival rate among patients with metastatic melanoma remains low, therefore, melanoma is responsible for the majority of skin cancer-related deaths. The ongoing investigation of natural antitumor agents, the nonpsychoactive cannabinoid, cannabigerol (CBG) found in Cannabis sativa is emerging as a promising candidate. CBG offers a potential therapeutic role in the treatment of melanoma demonstrating cell growth inhibition in some tumors. Its low water solubility and bioavailability hinder the potential effectiveness. To address these challenges, a modified CBG, namely LE-127/2 was synthesized by Mannich-type reaction. The aim was to investigate the effect of this novel compound on cell proliferation as well as the mechanism of cell death with a particular focus on autophagy and apoptosis. Human cutan melanoma cell lines, WM35, A2058 and WM3000 were utilized for the present study. Cell proliferation of the cells after the treatment with LE-127/2, parent CBG or vemurafenib was assessed by Cell Titer Blue Assay. Cells were treated with a 1.25–80 µM of the above-mentioned compounds, and it was found that at 20 μM of all drugs showed a comparable effective inhibition of cell proliferation, however, vemurafenib and CBG proved to be more effective than LE-127/2. In addition, clonogenic cell survival assays were performed to examine the inhibitory effect of LE-127/2 on the colony formation ability of melanoma cell lines. Cells treated with 20 µM of LE-127/2 for 14 days showed about a 50% suppression of clonogenic cell survival. LE-127/2 exerted the most intensive inhibition on A2058 cell colonies. Furthermore, notably, LDH cytotoxicity assay performed on HaCaT cell line, proved LE-127/2 to be cytotoxic only at higher concentration, such as 80 μM, while the parent CBG was cytotoxic at concentration as low as 5 μM, suggesting that the new CBG derivative as a drug candidate may be applied in human pharmacotherapy without causing a substantial damage in intact epidermal cells. Analysis of protein expression revealed the impact of LE-127/2 on the expression of basic proteins (LC-3, Beclin-1 and p62) involved in the process of autophagy in the three different melanoma cell lines studied. Elevated expression of these proteins was detected as a result of LE-127/2 (20 µM) treatment. LE-127/2 also induced the expression of some proteins involved in apoptosis, and it is particularly noteworthy the increased level of cleaved PARP. Based on the results obtained, it can be concluded that LE-127/2 induced autophagy could lead to the inhibition of cell proliferation and death in melanoma cells.