Pathogenesis Of Cutaneous Melanoma Research Articles

The development and experimental validation of hypoxia-related long noncoding RNAs prognostic signature in predicting prognosis and immunotherapy of cutaneous melanoma.

Cutaneous melanoma (CM) is widely acknowledged as a highly aggressive form of malignancy that is associated with a considerable degree of morbidity and poor prognosis. Despite this recognition, the precise role of hypoxia-related long noncoding RNAs (HRLs) in the pathogenesis of CM remains an area of active research. This study sought to elucidate the contribution of HRLs in CM by conducting a thorough screening and extraction of hypoxia-related genes (HRGs). In particular, we conducted univariate and multivariate Cox regression analyses to assess the independence of the prognostic signature of HRLs. Our results demonstrated that a novel risk model could be established based on five prognostic HRLs. Remarkably, patients with low-risk scores exhibited significantly higher overall survival rates compared to their high-risk counterparts, as confirmed by Kaplan-Meier survival analysis. Furthermore, we utilized consensus clustering analysis to categorize CM patients into two distinct subtypes, which revealed marked differences in their prognosis and immune infiltration landscapes. Our nomogram results confirmed that the HRLs prognostic signature served as an independent prognostic indicator, offering an accurate evaluation of the survival probability of CM patients. Notably, our findings from ESTIMATE and ssGSEA analyses highlighted significant disparities in the immune infiltration landscape between low- and high-risk groups of CM patients. Additionally, IPS and TIDE results suggested that CM patients in different risk subtypes may exhibit favorable responses to immunotherapy. Enrichment analysis and GSVA results indicated that immune-related signaling pathways may mediate the role of HRLs in CM. Finally, our tumor mutation burden (TMB) results indicated that patients with low-risk scores had a higher TMB status. In summary, the establishment of a risk model based on HRLs in this study provided an accurate prognostic prediction and correlated with the immune infiltration landscape of CM, thereby providing novel insights for the future clinical management of this disease.

Cutaneous Melanoma: A Review of Multifactorial Pathogenesis, Immunohistochemistry, and Emerging Biomarkers for Early Detection and Management.

Cutaneous melanoma (CM) is an increasingly significant public health concern. Due to alarming mortality rates and escalating incidence, it is crucial to understand its etiology and identify emerging biomarkers for improved diagnosis and treatment strategies. This review aims to provide a comprehensive overview of the multifactorial etiology of CM, underscore the importance of early detection, discuss the molecular mechanisms behind melanoma development and progression, and shed light on the role of the potential biomarkers in diagnosis and treatment. The pathogenesis of CM involves a complex interplay of genetic predispositions and environmental exposures, ultraviolet radiation exposure being the predominant environmental risk factor. The emergence of new biomarkers, such as novel immunohistochemical markers, gene mutation analysis, microRNA, and exosome protein expressions, holds promise for improved early detection, and prognostic and personalized therapeutic strategies.

Identification of genomic-wide genetic links between cutaneous melanoma and obesity-related physical traits via cFDR.

Both epidemiological and clinical studies have suggested the comorbidity between cutaneous melanoma (CM) and obesity-related physical traits. However, it remains unclear about their shared genetic architecture. To determine the shared genetic architecture between CM and obesity-related physical traits through conditional false discovery rate (cFDR) analysis. Quantile-quantile plots were firstly built to assess the pleiotropic enrichment of shared single nucleotide polymorphisms between CM and each trait. Then, cFDR and conjunctional cFDR (ccFDR) were used to identify the shared risk loci between CM and each trait. Moreover, the functional evaluation of shared risk genes was carried out through analyses of expression quantitative trait loci (eQTL), Kyoto Encyclopedia of Genes and Genomes and gene ontology, respectively. Finally, single-cell sequence analysis was performed to locate the expression of eQTL-mapped genes in tissues. Successive pleiotropic enrichment was found between CM and 5 obesity-related traits or height. 24 shared risk loci were identified between CM and 13 traits except appendicular lean mass using ccFDR analysis, with 17 novel and 4 validated loci. The functions of ccFDR-identified and eQTL-mapped genes were revealed to be mainly involved in cellular senescence, proliferation, meiotic nuclear division, cell cycle, and the metabolism of lipid, cholesterol and glucose. Single-cell sequence analysis showed that keratinocytes contribute to the occurrence and aggressiveness of CM through secreting paracrine cytokines. Our findings demonstrate the significant genetic correlation between CM and obesity-related physical traits, which may provide a novel genetical basis for the pathogenesis and treatment of CM.

Phosphatase and Tensin Homolog (PTEN) Expression as a Surrogate Biomarker Correlated With the Depth of Invasion in Cutaneous Malignant Melanoma.

Objective The aim of this study is to evaluate the expression of the phosphatase and tensin homolog (PTEN), which is a tumor suppressor gene that is implicated in the pathogenesis of cutaneous malignant melanoma, in normal skin and melanoma tissue samples. The study also aimed to correlate PTEN expression levels with various clinicopathological parameters of melanoma lesions, thus highlighting the utility of PTEN expression as a prognostic biomarker for melanoma. Study design Immunohistochemistry (IHC) staining was performed on tissue microarray samples representing normal skin and melanoma biopsies of different clinicopathological parameters. Tissue photomicrographs were evaluated with Aperio ImageScope, which has a positive-pixel-counting algorithm built in. Subsequently, a histochemical score (H-score) was derived from the percentage of positive cells (%-staining) and their staining intensity. The H-scores were averaged in groups of tissue samples representing the different melanomas' tumor (T), node (N), and distant metastasis (M), also known as TNM parameters, as set forth by the American Joint Committee on Cancer (AJCC) classification. The mean H-scores were statistically compared using a two-tailed unpaired t-test. Results The PTEN protein expression was measured by IHC and found to be correlated with tumor thickness (T), which is a reliable indicator for survival rates. Specifically, PTEN was significantly downregulated in tumors with a thickness over 2 mm (T3+T4) compared to tumors with a thickness at or below 2 mm (T1+T2). Conclusions The PTEN protein expression, as measured by immunohistochemistry, helped differentiate between tumors with a thickness over 2 mm and tumors with a thickness at or below 2 mm, suggesting PTEN as a potential surrogate marker for the melanoma's invasion depth along with possible prognostic implications. Longitudinal studies evaluating risk stratification based on the expression of PTEN are needed to establish the utility of this promising biomarker in the clinic as an adjunct for pathological examination.

Role of Single Nucleotide Polymorphism-Related Genes in Tumour Immune Cell Infiltration and Prognosis of Cutaneous Melanoma.

Advances in cancer research have allowed for early diagnosis and improved treatment of cutaneous melanoma (CM). However, its invasiveness and recurrent metastasis, along with rising resistance to newer therapies, have lent urgency to the search for novel biomarkers and the underlying molecular mechanisms of CM. Single nucleotide polymorphism- (SNP-) related genes were obtained from the sequencing data of 428 CM samples in The Cancer Genome Atlas. Functional enrichment of these genes was analysed in clusterProfiler. Additionally, a protein-protein interaction (PPI) network was constructed with the Search Tool for the Retrieval of Interacting Gene (STRING) database. Gene Expression Profiling Interactive Analysis (GEPIA) was used to identify the expression and prognostic value of mutated genes. Finally, the Tumour Immune Estimation Resource (TIMER) analysed the relationship between gene expression and immune cell infiltration. We constructed a PPI network from the top 60 SNP-related genes. Mutated genes were mainly involved in calcium and oxytocin signalling pathways, as well as circadian entrainment. In addition, three SNP-related genes, BRAF, FLG, and SORL1, were significantly associated with patient prognosis. BRAF and SORL1 were positively associated with infiltration abundance of B cells, CD8+ T cells, CD4+ T cells, neutrophils, and dendritic cells, whereas FLG expression was negatively associated. Furthermore, higher immune cell infiltration was positively correlated with good prognosis. Our study provides vital bioinformatic data and a relevant theoretical basis to further explore the molecular pathogenesis of CM and improve patient prognosis.

Aetiology and Pathogenesis of Cutaneous Melanoma: Current Concepts and Advances.

Melanoma develops from malignant transformations of the pigment-producing melanocytes. If located in the basal layer of the skin epidermis, melanoma is referred to as cutaneous, which is more frequent. However, as melanocytes are be found in the eyes, ears, gastrointestinal tract, genitalia, urinary system, and meninges, cases of mucosal melanoma or other types (e.g., ocular) may occur. The incidence and morbidity of cutaneous melanoma (cM) are constantly increasing worldwide. Australia and New Zealand are world leaders in this regard with a morbidity rate of 54/100,000 and a mortality rate of 5.6/100,000 for 2015. The aim of this review is to consolidate and present the data related to the aetiology and pathogenesis of cutaneous melanoma, thus rendering them easier to understand. In this article we will discuss these problems and the possible impacts on treatment for this disease.

Identification of novel biomarkers and candidate small-molecule drugs in cutaneous melanoma by comprehensive gene microarrays analysis.

Background: Melanoma is a pernicious skin cancer with high aggressiveness. This study aimed to identify potential novel biomarkers associated with the prognosis and pathogenesis of cutaneous melanoma and to explore new targeted drugs for melanoma. Methods: Two Gene Expression Omnibus (GEO) microarray datasets, GSE3189 and GSE7553 were combined to analyze the differentially expressed genes (DEGs). To better understand the DEGs in the melanoma pathogenesis, we performed gene enrichment analyses and established a protein-protein interaction network (PPI). The survival analyses for key genes were conducted based on the GEPIA platform. Finally, we mined the CMap database to explore potential small-molecule drugs to target the obtained DEGs. Results: In short, we identified 500 DEGs between cutaneous melanoma samples and normal samples. The PPI network was established with 349 nodes and 1251 edges. Signaling pathway analysis showed that these genes play a vital role in ECM-receptor interactions, the PPAR signaling pathway and pathways in cancer. Eight DEGs with a relatively high degree of connectivity (CDC45, CENPF, DTL, FANCI, GINS2, HJURP, TPX2 and TRIP13) were selected as hub-genes that remarkably correlated to a poor survival rate. Based on 500 DEGs, 20 small-molecule drugs that potentially target genes with abnormal expression in cutaneous melanoma were obtained from the CMap database. Among these compounds, we found that menadione has the greatest therapeutic value for melanoma. Conclusions: In conclusion, we identified the 8 candidate biomarkers and potential key signaling pathways in cutaneous melanoma through comprehensive microarray analyses. The identified candidate drugs have provided several directive significances for the synthesis medicine for melanoma.

BAP1 deletion abrogates growth and metastasis of murine cutaneous melanoma.

Although germline mutations in BRCA-associated protein-1 (BAP1) predispose to cutaneous melanoma (CM), BAP1 is rarely mutated in primary CM outside the familial context. The role of BAP1 in the pathogenesis of CM remains obscure. Here, we discovered an unexpected role of BAP1 in suppressing CM growth and metastasis. BAP1 deletion by CRISPR-Cas9 system severely compromises colony-forming capability of murine CM cell line B16-F10 and human CM cell lines, SK-MEL-28 and A375. Furthermore, BAP1 loss abrogates tumor growth and lung metastasis in murine syngeneic tumor models. Deletion of BAP1 in B16-F10 cells leads to preferential downregulation of genes accompanied with increased H2A ubiquitination at lysine 119. Transcriptomic characterization of BAP1 deletion reveals multiple deregulated cellular functions including extracellular matrix-receptor interaction and MAPK signaling pathway which may contribute to BAP1's effect on metastasis and proliferation. Our findings indicate that BAP1 could be a potential therapeutic target for CM.

Identification of key genes involved in the pathogenesis of cutaneous melanoma using bioinformatics analysis.

ObjectiveMalignant melanoma is a highly invasive cancer whose pathogenesis remains unclear. We analyzed the microarray dataset GDS1375 in the Gene Expression Omnibus database to search for key genes involved in the occurrence and development of melanoma.MethodsThe dataset included 52 samples (7 normal skin and 45 melanoma samples). We identified differentially expressed genes (DEGs) between the two groups and used integrated discovery databases for Gene Ontology (GO) and Kyoto Gene and Genome Encyclopedia (KEGG) pathway analyses. In addition, we used the STRING and MCODE plugins of Cytoscape to visualize the protein-protein interactions (PPI) for these DEGs.ResultsA total of 509 upregulated and 618 downregulated DEGs were identified, which were enriched in GO terms including integrin binding, protein binding, and structural constituent of cytoskeleton, and in KEGG pathways such as melanogenesis, prostate cancer, focal adhesion, and renin secretion. Three major modules from the PPI networks and 10 hub genes were identified, including CDC20, GNB2, PPP2R1A, AURKB, POLR2E, and AGTR1. Overall survival was low when these six hub genes were highly expressed.ConclusionThis bioinformatics analysis identified hub genes that may promote the development of melanoma and represent potential new biomarkers for diagnosis and treatment of melanoma.

NAV2 facilitates invasion of cutaneous melanoma cells by targeting SNAI2 through the GSK-3β/β-catenin pathway.

Previous studies have identified neuron navigator 2(NAV2) as an oncogene in several human tumors. However, the NAV2 gene expression changes and its role in the pathogenesis of cutaneous melanoma have not been clearly illustrated. Further investigations of NAV2 in cutaneous melanoma may provide new mechanistic insight and treatment strategy for this disease. Through immunohistochemistry assay and bioinformatics analysis, we found that melanoma tissues showed an upregulated expression of NAV2 which correlated with poor prognosis of cutaneous melanoma. To investigate the effect of NAV2 on the proliferation and invasion of melanoma, shNAV2 and NAV2-cDNA were transfected into melanoma cell lines. NAV2 overexpression significantly promoted melanoma cell proliferation, migration and invasion, while NAV2 silencing effectively inhibited this process. The potential underlying mechanisms were investigated using bioinformatics analysis, qRT-PCR, and western blot. Results showed that NAV2-mediated invasion of melanoma cells was driven by enhanced epithelial-mesenchymal transition, which was resulted from SNAI2 upregulation via the GSK-3β/β-catenin pathway. This study suggested that NAV2 could induce melanoma proliferation and invasion by epithelial-mesenchymal transition through the GSK-3β/β-catenin-SNAI2 pathway. Our findings on the pathological mechanisms of NAV2-associated cutaneous melanoma may contribute to the development of potential therapeutic strategy for melanoma.

EGFL7 silencing inactivates the Notch signaling pathway; enhancing cell apoptosis and suppressing cell proliferation in human cutaneous melanoma.

Melanoma is the main cause of death in patients with skin cancer. While the pathogenesis of cutaneous melanoma is poorly understood, increasing evidence shows that epidermal growth factor (EGF) may be involved. Herein, we tested the hypothesis that down-regulation of EGFL7 inhibits development and progression of human cutaneous melanoma (CM). Initially, we performed immunohistochemical analysis of EGFL7 in 130 specimens and the findings indicated that EGFL7 was highly expressed in CM. The expressions of EGFL7 and Notch signaling pathway-related genes in CM were then measured by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blot assay. In order to assess biological functions of EGFL7 in CM we up-regulated or down-regulated endogenous EGFL7 using EGFL7-OE or shRNA against EGFL7 in the A375 CM cell line. To better understand the pivotal role of Notch signaling pathway in CM, we blocked this pathway in A375 cells by inhibitor treatment. Finally, tumor xenograft in nude mice was performed to test the in vivo tumorigenesis of the transfected A375 cells. While EGFL7 activated the Notch signaling pathway in CM, gain- and loss-of-function studies established that decreased EGFL7 inhibited cell proliferation and promoted apoptosis in A375 cells. Moreover, down-regulated EGFL7 suppressed in vivo tumorigenesis. Most importantly, we determined that down-regulating EGFL7 inhibited CM development by suppressing the Notch signaling pathway. The combined findings define potential roles of decreased EGFL7 as inhibitors of CM development by suppressing the Notch signaling pathway, and EGFL7 may therefore be a novel therapeutic target in cutaneous melanoma patients.

Expression of Notch pathway receptors and ligands in cutaneous malignant melanoma

Objective To determine the expression of Notch pathway receptors (Notch1 and Notch4) and ligands (Jagged1 and Dll4) in cutaneous malignant melanoma (CMM) tissues, and to preliminarily explore the role of the Notch signaling pathway in the pathogenesis of CMM. Methods Immunohistochemical study was performed to determine the expression pattern and intensity of Notch1, Notch4, Jagged1 and Dll4 in 40 paraffin-embedded CMM specimens and 15 paraffin-embedded pigmented nevus specimens. Statistical analysis was carried out by chi-square test and Spearman rank correlation analysis with the SPSS 21.0 software. Results Notch1 was detected in 31 (77.5%) of 40 CMM specimens, as well as in 3 of 15 pigmented nevus specimens, and the positive rates significantly differed between the two groups (χ2= 15.281, P < 0.001) . However, no significant difference in the expression intensity of Notch1 was observed between 18 in situ melanoma tissues and 22 invasive melanoma tissues (χ2= 0.631, P= 0.427) . In addition, the positive rates of Notch4, Jagged1 and Dll4 were also significantly higher in the CMM group than those in the pigmented nevus group (all P < 0.05) , and the expression intensity of Notch4, Jagged1 and Dll4 significantly differed between in situ and invasive melanoma tissues (all P < 0.05) . In CMM tissues, the expression of Notch1 was positively correlated with that of Jagged1 (rs= 0.350, P= 0.027) and Dll4 (rs= 0.562, P < 0.001) , while the expression of Jagged1 was negatively correlated with that of Dll4 (rs=-0.734, P < 0.001) . Conclusion Abnormality of the Notch signaling pathway may be involved in the pathogenesis of melanoma, but further researches are still needed to elucidate the detailed mechanism. Key words: Nevi and melanomas; Receptors, Notch; Immunohistochemistry; Jagged1; Dll4

Long non-coding RNAs in cutaneous melanoma: clinical perspectives.

Metastatic melanoma of the skin has a high mortality despite the recent introduction of targeted therapy and immunotherapy. Long non-coding RNAs (lncRNAs) are defined as transcripts of more than 200 nucleotides in length that lack protein-coding potential. There is growing evidence that lncRNAs play an important role in gene regulation, including oncogenesis. We present 13 lncRNA genes involved in the pathogenesis of cutaneous melanoma through a variety of pathways and molecular interactions. Some of these lncRNAs are possible biomarkers or therapeutic targets for malignant melanoma.

Mitogen-Activated Protein Kinase Signaling Pathway in Cutaneous Melanoma: An Updated Review.

The mitogen-activated protein kinase (MAPK) signaling pathway is a cascade of protein kinases that act in a sequential and predominantly linear fashion, albeit displaying some cross talk with other signaling cascades. Mutations in proteins integral to the MAPK signaling pathway are present in more than 50% of cutaneous melanomas. The most frequently mutated protein is v-raf murine sarcoma viral oncogene homolog B (BRAF), followed by neuroblastoma Ras viral oncogene homolog (NRAS). Recently, the development of targeted drugs for the treatment of BRAF-mutant melanoma has led to the widespread implementation of molecular assays for the detection of specific BRAF mutations. There have been some attempts to standardize testing of BRAF mutations, but this has not been achieved so far. Here we provide an updated review on the role of the MAPK signaling pathway in the pathogenesis of cutaneous melanoma, focusing on several different BRAF mutations and their diagnostic and therapeutic implications.

The effect of solar ultraviolet radiation (UVR) on induction of skin cancers

Ultraviolet radiation is a physical mutagenic and cancerogenic factor. About 95% of ultraviolet A (UVA) (320-400 nm) and 5% of UVB (280-320 nm) reach the Earth's surface. Melanin is a natural skin protective factor against UV radiation. Skin cancers associated with long-term exposure to UV radiation are: basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and cutaneous malignant melanoma (CMM). The high risk of BCC development is related to acute and repeated exposure to UV causing sunburn. Molecular studies of BBC demonstrated disorders in sonic hedgehog (SHH) cell signaling regulation pathway, associated with the suppressor protein patched homolog 1 gene (PTCH1) mutations. The risk of the BCC development is related to the polymorphism of melanokortin-1 receptor gene (MC1R). Tumor P53 gene mutations observed in BCC cells has been classified as secondary genetic changes. In SCC cells UV-induced mutations were mostly related to P53 gene. Increased expression of cyclooxigenase- 2 gene (COX-2) plays a significant role in the development of SCC. Other pathogenetic factors include intensification of the synthesis of pro-inflammatory cytokines (tumor necrosis factor α (TNF-α), interleukin-1 α (IL-1α), IL-1β and IL-6). Currently, the role of UVB has been recognized in the pathogenesis of CMM. In CMM cells the following gene mutations were noted: cyclindependent kinase inhibitor 2A INK4A (p16INK4A), cyclin-dependent kinase 4 (CDK4), Ras, phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and proto-oncogene B-Raf (BRAF). The BRAF gene mutations were observed in ~50% of CMM cases. Mutations of P53 gene are not characteristic of CMM cells. Med Pr 2016;67(2):255-266.

Expressions of STAT3 and phosphorylated STAT3 in cutaneous malignant melanoma lesions

Objective To investigate expressions of STAT3 and phosphorylated STAT3 (p-STAT3) in cutaneous malignant melanoma (CMM) lesions, and to explore their significance. Methods The expressions of STAT3 and p-STAT3 were detected with an immunohistochemical method using polymer enzyme-labeled secondary antibodies in skin specimens from 22 CMM lesions and 23 pigmented nevus lesions. The effects of STAT3 and p-STAT3 expressions on lymph node metastasis of CMM were evaluated. Results The expression rate of STAT3 was significantly higher in CMM lesions than in pigmented nevus lesions (95.5% vs. 56.5%, χ2 = 9.23, P 0.05), while the elevated expression of p-STAT3 in CMM lesions was a predictive factor for lymph node metastasis in CMM (OR = 1.88, 95% CI: 1.05 - 3.38, P< 0.05). Conclusion Increased expression of STAT3 and p-STAT3 in CMM may play important roles in the pathogenesis of CMM, and elevated p-STAT3 expression may contribute to invasion and metastasis of CMM. Key words: Melanoma; STAT3 transcription factor; Lymphatic metastasis; p-STAT3

BAP1 Has a Survival Role in Cutaneous Melanoma

Although the pattern of BAP1 inactivation in ocular melanoma specimens and in the BAP1 cutaneous/ocular melanoma (CM/OM) predisposition syndrome suggests a tumor suppressor function, the specific role of this gene in the pathogenesis of cutaneous melanoma is not fully understood. We thus set out to characterize BAP1 in cutaneous melanoma and discovered an unexpected pro-survival effect of this protein. Tissue and cell lines analysis showed that BAP1 expression was maintained, rather than lost, in primary melanomas compared to nevi and normal skin. Genetic depletion of BAP1 in melanoma cells reduced proliferation and colony forming capability, induced apoptosis and inhibited melanoma tumor growth in vivo. On the molecular level, suppression of BAP1 led to a concomitant drop in the protein levels of survivin a member of anti-apoptotic proteins and a known mediator of melanoma survival. Restoration of survivin in melanoma cells partially rescued the growth-retarding effects of BAP1 loss. In contrast to melanoma cells, stable overexpression of BAP1 into immortalized but non-transformed melanocytes did suppress proliferation and reduce survivin. Taken together, these studies demonstrate that BAP1 may play a growth-sustaining role in melanoma cells, but that its impact on ubiquitination underpins a complex physiology which is context and cell dependent.

Histopathological atlas and proposed classification for melanocytic lesions in Tyr::NRasQ61K; Cdkn2a−/− transgenic mice

Reference EPFL-ARTICLE-188431doi:10.1111/pcmr.12115View record in Web of Science Record created on 2013-09-09, modified on 2017-05-12

Comparative microarray analysis of microRNA expression profiles in primary cutaneous malignant melanoma, cutaneous malignant melanoma metastases, and benign melanocytic nevi

Perturbations in microRNA (miRNA) expression profiles have been reported for cutaneous malignant melanoma (CMM) predominantly when examined in cell lines. Despite the rapidly growing number of newly discovered human miRNA sequences, the availability of up-to-date miRNA expression profiles for clinical samples of primary cutaneous malignant melanoma (PCMM), cutaneous malignant melanoma metastases (CMMM), and benign melanocytic nevi (BMN) is limited. Specimens excised from the center of tumors (lesional) from patients with PCMM (n=9), CMMM (n=4), or BMN (n=8) were obtained during surgery. An exploratory microarray analysis was performed by miRNA expression profiling based on Agilent platform screening for 1205 human miRNAs. The results from the microarray analysis were validated by TaqMan quantitative real-time polymerase chain reaction. In addition to several miRNAs previously known to be associated with CMM, 19 unidentified miRNA candidates were found to be dysregulated in CMM patient samples. Among the 19 novel miRNA candidates, the genes hsa-miR-22, hsa-miR-130b, hsa-miR-146b-5p, hsa-miR-223, hsa-miR-301a, hsa-miR-484, hsa-miR-663, hsa-miR-720, hsa-miR-1260, hsa-miR-1274a, hsa-miR-1274b, hsa-miR-3663-3p, hsa-miR-4281, and hsa-miR-4286 were upregulated, and the genes hsa-miR-24-1*, hsa-miR-26a, hsa-miR-4291, hsa-miR-4317, and hsa-miR-4324 were downregulated. The results of this study partially confirm previous CMM miRNA profiling studies identifying miRNAs that are dysregulated in CMM. However, we report several novel miRNA candidates in CMM tumors; these miRNA sequences require further validation and functional analysis to evaluate whether they play a role in the pathogenesis of CMM.

Aberrations in the micro‐RNA biogenesis machinery and the emerging roles of micro‐RNAs in the pathogenesis of cutaneous malignant melanoma

Micro-RNAs (miRNAs) are small noncoding RNAs that play roles in the posttranscriptional regulation of gene expression. Since the seminal discovery that aberrant miRNA expression has a causative role in leukemogenesis, the involvement of miRNAs in cancer initiation, propagation, and metastasis has been widely studied. In this review, we provide a comprehensive summary of the literature on miRNAs in melanoma, specifically focusing on aberrations in cellular miRNA biogenesis and processing. These aberrations include genetic and epigenetic changes at the chromosomal level, alterations in the level of the miRNA-processing enzyme DICER, and the existence of competitive endogenous RNAs that serve as decoys for miRNAs and thus modulate their effective intracellular concentrations. We also discuss miRNA profiling in melanoma, review several miRNAs implicated in invasion, metastasis, proliferation, and apoptosis, and briefly summarize the cross talk between miRNAs and microphthalmia-associated transcription factor, the master transcriptional regulator of the melanocyte lineage. Finally, we summarize recent studies of miRNA expression as prognostic and predictive biomarkers, as well as initial experiments on the use of miRNAs and small interfering RNAs as therapeutic agents in melanoma.