MicroRNAs role as potential biomarkers and key regulators in melanoma

Sex-dependent interaction of PTGS2 with miR-146a as risk factor for melanoma and the impact of sex hormones in gene expression in skin cells

Gender disparity in melanoma is a complex issue where sex hormones could be engaged. Differences in genetic variations are important in understanding the mechanisms of sex disparity in melanoma. Post-transcriptional regulation of prostaglandin-endoperoxide synthase (PTGS2) mRNA occurs through a complex interplay of specific trans-acting RNA-binding proteins and microRNAs. MiR-146a is a key player in melanoma, modulating immune responses and tumor microenvironment (TME). Polymorphisms in PTGS2 gene rs20415GC have been associated with an increased risk of melanoma. Epistasis between polymorphisms rs20415GC was investigated by genotyping 453 melanoma patients and 382 control individuals. The effects of testosterone and 17β-estradiol were analyzed in keratinocytes and two melanoma cell lines. The rs2910164GG showed a higher risk in the presence of the genotype rs20417CC in the male population. Testosterone and 17β-estradiol act differently on PTGS2 and miR-146a expression, depending on the cell type. Testosterone augments PTGS2 gene expression in keratinocytes and miR-146a in melanoma cells. While 17β-estradiol only increases miR-146a expression in HaCaT cells. The present study indicates a sex-specific relation between miR-146a and PTGS2 polymorphisms with melanoma cancer risk. Testosterone and 17β-estradiol act differently on the expression of PTGS2 and miR-146a depending on the skin cell type.

Investigating the tumor-immune microenvironment through extracellular vesicles from frozen patient biopsies and 3D cultures

Melanomas are highly immunogenic tumors that have been shown to activate the immune response. Nonetheless, a significant portion of melanoma cases are either unresponsive to immunotherapy or relapsed due to acquired resistance. During melanomagenesis, melanoma and immune cells undergo immunomodulatory mechanisms that aid in immune resistance and evasion. The crosstalk within melanoma microenvironment is facilitated through the secretion of soluble factors, growth factors, cytokines, and chemokines. In addition, the release and uptake of secretory vesicles known as extracellular vesicles (EVs) play a key role in shaping the tumor microenvironment (TME). Melanoma-derived EVs have been implicated in immune suppression and escape, promoting tumor progression. In the context of cancer patients, EVs are usually isolated from biofluids such as serum, urine, and saliva. Nonetheless, this approach neglects the fact that biofluid-derived EVs reflect not only the tumor, but also include contributions from different organs and cell types. For that, isolating EVs from tissue samples allows for studying different cell populations resident at the tumor site, such as tumor-infiltrating lymphocytes and their secreted EVs, which play a central anti-tumor role. Herein, we outline the first instance of a method for EV isolation from frozen tissue samples at high purity and sensitivity that can be easily reproduced without the need for complicated isolation methods. Our method of processing the tissue not only circumvents the need for hard-to-acquire freshly isolated tissue samples, but also preserves EV surface proteins which allows for multiplex surface markers profiling. Tissue-derived EVs provide insight into the physiological role of EVs enrichment at tumor sites, which can be overlooked when studying circulating EVs coming from different sources. Tissue-derived EVs could be further characterized in terms of their genomics and proteomics to identify possible mechanisms for regulating the TME. Additionally, identified markers could be correlated to overall patient survival and disease progression for prognostic purposes.

Circulating microRNAs as diagnostic biomarkers for melanoma: a systematic review and meta-analysis

BACKGROUND

Recent studies have shown that circulating microRNAs (miRNAs) can be used as diagnostic biomarkers for melanoma. This study aimed to evaluate the diagnostic value of circulating miRNAs for melanoma.

METHODS

A comprehensive literature search was conducted and the quality of the included literature was evaluated using QUADAS-2 (Quality Assessment for diagnostic accuracy studies), and the diagnostic accuracy was assessed by pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under the curve (AUC). We used Deeks' funnel plot to evaluate publication bias.

RESULTS

The meta-analysis included 10 articles covering 16 studies, and the results showed that circulating miRNAs provide high diagnostic accuracy for melanoma. The overall pooled sensitivity was 0.87 (95% CI: 0.82-0.91), specificity was 0.81 (95% CI: 0.77-0.85), PLR was 4.6 (95% CI: 3.7-5.8), NLR was 0.16 (95% CI: 0.11-0.23), DOR was 29 (95% CI: 18-49), and AUC was 0.90 (95% CI: 0.87-0.92), respectively. Subgroup analysis showed better diagnostic value in miRNA clusters, European population, plasma miRNAs, and upregulated miRNAs compared to other subgroups.

CONCLUSIONS

The results indicated that circulating microRNAs can be used as a non-invasive biomarker for the diagnosis of melanoma.

Circular RNA, hsa_circRNA_102049, promotes colorectal cancer cell migration and invasion via binding and suppressing miRNA-455-3p

Colorectal cancer (CRC) is the second most prevalent malignant gastrointestinal tumor type worldwide, displaying poor prognosis. Accumulating studies have reported the significance of circular RNAs (circRNAs) and microRNAs (miRNAs) in CRC carcinogenesis and development. At present, the functions and mechanisms of action underlying the circular RNA, hsa_circRNA_102049, in CRC are not completely understood. The present study aimed to establish the involvement of hsa_circRNA_102049 in CRC, as well as the associated mechanisms. The expression levels of hsa_circRNA_102049 and miRNA-455-3p were measured in CRC cell lines and tissues via reverse transcription-quantitative PCR. CRC progression was evaluated by performing Cell Counting Kit-8, flow cytometry, wound healing and Transwell invasion assays. The results demonstrated that hsa_circRNA_102049 was highly expressed in both CRC tissues and cell lines, which was associated with enhanced CRC cell proliferation, migration and invasion. Furthermore, miR-455-3p expression was downregulated in CRC cells and served as a target of has_circRNA_102049, which was validated by performing the dual luciferase reporter assay. hsa_circRNA_102049 knockdown significantly increased miR-455-3p expression, which was significantly reversed by co-transfection with the miR-455-3p inhibitor. Notably, miRNA-455-3p overexpression alleviated hsa_circRNA_102049-mediated induction of CRC cell proliferation, migration and invasion. The present study clearly demonstrated that miRNA-455-3p was a target of hsa_circRNA_102049. Moreover, the results indicated that the circular RNA, hsa_circRNA_102049, may function as a tumor promoter in CRC via directly sponging miRNA-455-3p.

MicroRNA-365 promotes apoptosis in human melanoma cell A375 treated with hydatid cyst fluid of Echinococcus granulosus sensu stricto

Hydatid cyst fluid (HCF)-based therapeutics has experimentally targeted approaches for treating human cancer cell lines. MicroRNA-365 (miR-365) has been reported to be an important tumor suppressor miRNA in cancers. However, it remains unknown, how miR-365 plays a pivotal role in inducing apoptosis in HCF-treated cancer cells in vitro. The fertile/infertile HCF was aspirated from liver of infected sheep and in terms of molecular taxonomy was identified as G1 genotype of Echinococcus granulosus sensu stricto. A375 human melanoma cancer cells were cultured into two groups: fertile and infertile HCF-treated A375 cells. To assess the cytotoxicity of various concentrations of HCF on melanoma cells, cell viability was determined by using MTT assay. The IC50 value of HCF on A375 cells was determined 85 μg/mL. Caspase-3 enzymatic activity was evaluated by fluorometric assay in the HCF-treated melanoma cells. In addition, the mRNA expression of Bax, Bcl-2, Caspase-9 and miR-365 were determined by qRT-PCR. Findings of MTT assay showed that concentrations 85 μg/mL to 100 μg/mL of fertile HCF have the highest mortality (50%-52%) on A375 cells during 24 h. The fold change of Bax/Bcl-2 ratio, Caspase-9, miR-365 and Caspase-3 activity was higher in the fertile HCF-treated melanoma cells compared to infertile fluid treated A375 cells and human normal epithelial cell (as control cell). In conclusion, we over-expressed the miR-365 in melanoma A375 cells, via treatment of fertile HCF. Our findings suggested that inducing high expression of miR-365 might be a negative regulator of melanoma growth through activation of pro-apoptotic Bax, Caspase-9 and Caspase-3 that are essential to intrinsic apoptotic pathway. These findings provide new insights into the use of Echinococcus HCF-derived metabolites in the design of drug therapies and in vivo tumor cell vaccine to combat melanoma progression.

MicroRNA‑195 suppresses cell proliferation, migration and invasion in epithelial ovarian carcinoma via inhibition of the CDC42/CCND1 pathway

Epithelial ovarian carcinoma (EOC) is the most common cause of gynecological cancer mortality, and poses a threat to women. MicroRNA-195 (miR-195) has been reported to induce apoptosis of human OVCAR-3 cells by inhibiting the VEGFR2/AKT pathway. However, the role of miR-195 in EOC remains unknown. A previous study reported that cell division cycle 42 (CDC42) can serve as a target gene of miR-195 and mediate malignant progression of esophageal squamous cell carcinoma (ESCC). The aim of the present study was to investigate the role of miR-195 in EOC and the regulation in CDC42/CCND1 pathway. Tissues samples and clinical materials were collected from 78 enrolled patients with EOC to analyze the expression and clinical significance of miR-195, CDC42 and cyclin D1 (CCND1). Human EOC cell lines OVCA420, OVCAR-3, A2780 and SKOV3 cell lines were used to assess the expression and function of miR-195, CDC42 and CCND1 in vitro. Cell proliferation, the cell cycle and apoptosis, as well as the cell migratory and invasive abilities were detected in vitro using BrdU incorporation, colony formation, wound healing and Transwell invasion assays, along with flow cytometry. miR-195 was downregulated, while CDC42 and CCND1 were upregulated in human EOC tissues and cells, and the aberrant expression of both was associated with increased EOC malignancy. Moreover, miR-195 expression was negatively correlated with CDC42 and CCND1 expression levels, and negatively regulated these expression levels. Thus, it was suggested that miR-195 functions as a tumor suppressor, but CDC42 and CCND1 act as tumor promoters based their abilities to enhance cell proliferation, cell cycle entry, migration and invasion, as well as decrease apoptosis in OVCAR-3 cells. the present results demonstrated that miR-195 inhibited human EOC progression by downregulating CDC42 and CCND1 expression. Furthermore, it was identified that miR-195, CDC42 and CCND1 may be effective biomarkers for EOC diagnosis and treatment.

Mechanisms of JAK-STAT signaling pathway mediated by CXCL8 gene silencing on epithelial-mesenchymal transition of human cutaneous melanoma cells

Effect of CXCL8 gene silencing-mediated JAK-STAT signaling pathway on epithelial-mesenchymal transition (EMT) of human cutaneous melanoma cells was explored. Eighty patients with cutaneous melanoma were enrolled in the study. Cells were transfected accordingly and divided into five groups: The blank group (human cutaneous melanoma cells), NC group (human cutaneous melanoma cells + blank vector plasmid transfection), CXCL8 siRNA group (human cutaneous melanoma cells + CXCL8 silent expression vector plasmid transfection), AG490 group (human cutaneous melanoma cells + JAK-STAT signal pathway inhibitor transfection), CXCL8 siRNA + AG490 group (human cutaneous melanoma cells + JAK-STAT signaling pathway inhibitor + CXCL8 silent expression vector plasmid transfection). The expression levels of CXCL8, JAK2, STAT3, epithelial cadherin (E-cadherin), neurotrophic cadherin (N-cadherin) and vimentin in tissues and cells were detected by RT-qPCR and western blot analysis. CCK-8 and flow cytometry were used to detect cell proliferation and apoptosis. Compared with adjacent normal tissues, the expression of E-cadherin in human cutaneous melanoma tissues was significantly decreased, whereas the expression of CXCL8, JAK2, STAT3, vimentin and N-cadherin was significantly increased (P<0.05). Compared with the blank group, CXCL8 siRNA group and CXCL8 siRNA + AG490 group had significantly lower expression of CXCL8 (P<0.05). Compared with the blank group, the expression levels of JAK2, STAT3, vimentin and N-cadherin in CXCL8 siRNA group, AG490 group and CXCL8 siRNA + AG490 group were decreased, the expression of E-cadherin was increased, the cell proliferation ability was decreased and apoptosis was increased (P<0.05). Compared with CXCL8 siRNA group, the expression of JAK2, STAT3, vimentin and N-cadherin in CXCL8 siRNA + AG490 group were significantly decreased, the expression of E-cadherin was significantly increased, cell proliferation ability was decreased and apoptosis was increased (P<0.05). In conclusion, CXCL8 gene expression silencing may inhibit EMT and cell proliferation while promoting cell apoptosis of human cutaneous melanoma cells by inhibiting the activation of JAK-STAT signaling pathway.

The differential expression of micro-RNAs 21, 200c, 204, 205, and 211 in benign, dysplastic and malignant melanocytic lesions and critical evaluation of their role as diagnostic biomarkers

Overlapping histological features between benign and malignant lesions and a lack of firm diagnostic criteria for malignancy result in high rates of inter-observer variation in the diagnosis of melanocytic lesions. We aimed to investigate the differential expression of five miRNAs (21, 200c, 204, 205, and 211) in benign naevi (n = 42), dysplastic naevi (n = 41), melanoma in situ (n = 42), and melanoma (n = 42) and evaluate their potential as diagnostic biomarkers of melanocytic lesions. Real-time PCR showed differential miRNA expression profiles between benign naevi; dysplastic naevi and melanoma in situ; and invasive melanoma. We applied a random forest machine learning algorithm to classify cases based on their miRNA expression profiles, which resulted in a ROC curve analysis of 0.99 for malignant melanoma and greater than 0.9 for all other groups. This indicates an overall very high accuracy of our panel of miRNAs as a diagnostic biomarker of benign, dysplastic, and malignant melanocytic lesions. However, the impact of variable lesion percentage and spatial expression patterns of miRNAs on these real-time PCR results was also considered. In situ hybridisation confirmed the expression of miRNA 21 and 211 in melanocytes, while demonstrating expression of miRNA 205 only in keratinocytes, thus calling into question its value as a biomarker of melanocytic lesions. In conclusion, we have validated some miRNAs, including miRNA 21 and 211, as potential diagnostic biomarkers of benign, dysplastic, and malignant melanocytic lesions. However, we also highlight the crucial importance of considering tissue morphology and spatial expression patterns when using molecular techniques for the discovery and validation of new biomarkers.

MicroRNAs as Key Players in Melanoma Cell Resistance to MAPK and Immune Checkpoint Inhibitors

Advances in the use of targeted and immune therapies have revolutionized the clinical management of melanoma patients, prolonging significantly their overall and progression-free survival. However, both targeted and immune therapies suffer limitations due to genetic mutations and epigenetic modifications, which determine a great heterogeneity and phenotypic plasticity of melanoma cells. Acquired resistance of melanoma patients to inhibitors of BRAF (BRAFi) and MEK (MEKi), which block the mitogen-activated protein kinase (MAPK) pathway, limits their prolonged use. On the other hand, immune checkpoint inhibitors improve the outcomes of patients in only a subset of them and the molecular mechanisms underlying lack of responses are under investigation. There is growing evidence that altered expression levels of microRNAs (miRNA)s induce drug-resistance in tumor cells and that restoring normal expression of dysregulated miRNAs may re-establish drug sensitivity. However, the relationship between specific miRNA signatures and acquired resistance of melanoma to MAPK and immune checkpoint inhibitors is still limited and not fully elucidated. In this review, we provide an updated overview of how miRNAs induce resistance or restore melanoma cell sensitivity to mitogen-activated protein kinase inhibitors (MAPKi) as well as on the relationship existing between miRNAs and immune evasion by melanoma cell resistant to MAPKi.

Clinical Relevance of Liquid Biopsy in Melanoma and Merkel Cell Carcinoma

Melanoma and Merkel cell carcinoma are two aggressive skin malignancies with high disease-related mortality and increasing incidence rates. Currently, invasive tumor tissue biopsy is the gold standard for their diagnosis, and no reliable easily accessible biomarker is available to monitor patients with melanoma or Merkel cell carcinoma during the disease course. In these last years, liquid biopsy has emerged as a candidate approach to overcome this limit and to identify biomarkers for early cancer diagnosis, prognosis, therapeutic response prediction, and patient follow-up. Liquid biopsy is a blood-based non-invasive procedure that allows the sequential analysis of circulating tumor cells, circulating cell-free and tumor DNA, and extracellular vesicles. These innovative biosources show similar features as the primary tumor from where they originated and represent an alternative to invasive solid tumor biopsy. In this review, the biology and technical challenges linked to the detection and analysis of the different circulating candidate biomarkers for melanoma and Merkel cell carcinoma are discussed as well as their clinical relevance.

miRNAs in the Diagnosis and Prognosis of Skin Cancer

Skin cancer is, at present, the most common type of malignancy in the Caucasian population. Its incidence has increased rapidly in the last decade for both melanoma and non-melanoma skin cancer. Differential expression profiles of microRNAs (miRNAs) have been reported for a variety of different cancers, including skin cancers. Since miRNAs’ discovery as regulators of gene expression, their importance grew in the field of oncology. miRNAs can post-transcriptionally regulate gene expression, tumor initiation, development progression, and aggressiveness. Nowadays, these short regulatory RNAs are perceived as one of the epigenetic markers for the identification of new diagnostic and/or prognostic molecular markers. Moreover, as miRNAs can drive tumorigenesis, they might eventually represent new therapy targets. Some miRNAs are pleiotropic, such as miR-214, which was found deregulated in several other tumors besides skin cancers. Some others are specific for one or more skin cancer types, like miR-21 and miR-221 for cutaneous melanoma and cutaneous squamous carcinoma or miR-155 for melanoma and cutaneous lymphoma. The goal of this review was to summarize some of the main miRNA detection technologies that are used to evaluate miRNAs in tissues and body fluids. Furthermore, their quantification limits, conformity, and robustness are discussed. Aberrant miRNA expression is analyzed for cutaneous melanoma, cutaneous squamous cell carcinoma (CSCC), skin lymphomas, cutaneous lymphoma, and Merkel cell carcinoma (MCC). In this type of disease, miRNAs are described as potential biomarkers to diagnose early lesion and/or early metastatic disease. In the future, whether in tissue or circulating in body fluids, miRNAs will gain their place in skin cancer diagnosis, prognosis, and future therapeutic targets.

The Expression of MIR17HG Protein as a Potential Therapeutic Target in Meningioma

BACKGROUND

MIR17 host gene (MIR17HG) is a potential therapeutic target for some cancer types. The aim of this study was to assess MIR17HG protein levels in patients with meningioma who had not been reported previously in the literature and comparing with normal meninges tissues.

METHODS

MIR17HG protein levels were measured in 46 samples including 25 meningioma tissues procured during surgery and 21 normal meninges tissues obtained within 4 hours of death during autopsy procedures. Each sample was stored at -80°C until the evaluation of MIR17HG protein using a sandwich enzyme-linked immunoassay principle. Results were compared between the groups.

RESULTS

MIR17HG protein levels were significantly higher in meningioma tissues compared with controls and difference was statistically significant (P = 0.012). Both World Health Organization grade I and grade II meningiomas had higher MIR17HG protein levels compared with controls and differences were statistically significant (P = 0.026 for grade I and P = 0.042 for grade II). Receiver operating characteristic curve analysis was performed to determine the cutoff of MIR17HG protein value in differentiating meningioma and control groups. At the cutoff value for MIR17HG protein of >0.0998 ng/mL, the sensitivity was 73.91%, 71.43%, and 77.78% and area under the curve was 0.756, 0.753, and 0.761 for meningioma group, grade I, and grade II subgroups, respectively, and specificity was 69.23% for each group.

CONCLUSIONS

MIR17HG protein expression was found to have a higher level in meningiomas than in normal meninges tissues in our study. Considering the recurrence and irresectability for some meningiomas, which require further treatment, MIR17HG may be a new target for treatment in meningiomas and our study will shed light on further studies.

Dissimilar Appearances Are Deceptive-Common microRNAs and Therapeutic Strategies in Liver Cancer and Melanoma

In this review, we summarize the current knowledge on miRNAs as therapeutic targets in two cancer types that were frequently described to be driven by miRNAs—melanoma and hepatocellular carcinoma (HCC). By focusing on common microRNAs and associated pathways in these—at first sight—dissimilar cancer types, we aim at revealing similar molecular mechanisms that are evolved in microRNA-biology to drive cancer progression. Thereby, we also want to outlay potential novel therapeutic strategies. After providing a brief introduction to general miRNA biology and basic information about HCC and melanoma, this review depicts prominent examples of potent oncomiRs and tumor-suppressor miRNAs, which have been proven to drive diverse cancer types including melanoma and HCC. To develop and apply miRNA-based therapeutics for cancer treatment in the future, it is essential to understand how miRNA dysregulation evolves during malignant transformation. Therefore, we highlight important aspects such as genetic alterations, miRNA editing and transcriptional regulation based on concrete examples. Furthermore, we expand our illustration by focusing on miRNA-associated proteins as well as other regulators of miRNAs which could also provide therapeutic targets. Finally, design and delivery strategies of miRNA-associated therapeutic agents as well as potential drawbacks are discussed to address the question of how miRNAs might contribute to cancer therapy in the future.

Circulating cell-free microRNAs in cutaneous melanoma staging and recurrence or survival prognosis

Cutaneous melanoma is a skin cancer with increasing incidence. Identification of novel clinical biomarkers able to detect the stage of disease and suggest prognosis could improve treatment and outcome for melanoma patients. Cell-free microRNAs (cf-miRNAs) are the circulating copies of short non-coding RNAs involved in gene expression regulation. They are released into the interstitial fluid, are detectable in blood and other body fluids and have interesting features of ideal biomarker candidates. They are stable outside the cell, tissue specific, vary along with cancer development and are sensitive to change in the disease course such as progression or therapeutic response. Moreover, they are accessible by non-invasive methods or venipuncture. Some articles have reported different cf-miRNAs with the potential of diagnostic tools for melanoma staging, recurrence and survival prediction. Although some concordance of results is already emerging, differences in analytical methods, normalization strategies and tumour staging still will require further research and standardization prior to clinical usage of cf-miRNA analysis. This article reviews this literature with the aim of contributing to a shared focusing on these new promising tools for melanoma treatment and care.

Correlation of MicroRNA 17-92 Cluster Host Gene (MIR17HG) Polymorphisms With Susceptibility and Prognosis for Multiple Myeloma

PURPOSE

To explore the correlation of MIR17HG polymorphism with susceptibility and prognosis of multiple myeloma (MM).

PATIENTS AND METHODS

A total of 217 MM patients treated with high-dose melphalan combined with autologous peripheral blood stem-cell transplantation at our hospital were enrolled as the case group, and 220 healthy people were included as the control group. Sequenom MassARRAY iPLEX Gold single nucleotide polymorphism genotyping was used to detect polymorphisms of MIR17HG, including rs7336610, rs17735387, rs4284505, and rs1428.

RESULTS

An increased risk of MM was found in patients who carried the rs7336610 T allele and rs4284505 G allele, and the higher the Durie-Salmon and International Staging System stages were, the more MM patients carrying rs7336610 CT + TT genotype and rs4284505 AG + GG genotype (all P < .05). Haplotype AC (rs4284505-rs1428) and CA (rs7336610-rs4284505) evidently reduce MM risk, whereas haplotype GC (rs4284505-rs1428) significantly elevated MM risk (all P < .05). Kaplan-Meier curve analysis demonstrated that rs7336610 CC genotype carriers had higher 5-year survival rate than CT + TT genotype carriers (P = .034), and the AA genotype carriers of rs4284505 had higher 5-year survival rate than AG + GG genotype carriers (P < .001).

CONCLUSION

Polymorphisms of MIR17HG rs7336610 and rs1428 were correlated with MM risk and prognosis.

Role of miRNAs in Melanoma Metastasis

Tumour metastasis is a multistep process. Melanoma is a highly aggressive cancer and metastasis accounts for the majority of patient deaths. microRNAs (miRNAs) are non-coding RNAs that affect the expression of their target genes. When aberrantly expressed they contribute to the development of melanoma. While miRNAs can act locally in the cell where they are synthesized, they can also influence the phenotype of neighboring melanoma cells or execute their function in the direct tumour microenvironment by modulating ECM (extracellular matrix) and the activity of fibroblasts, endothelial cells, and immune cells. miRNAs are involved in all stages of melanoma metastasis, including intravasation into the lumina of vessels, survival during circulation in cardiovascular or lymphatic systems, extravasation, and formation of the pre-metastatic niche in distant organs. miRNAs contribute to metabolic alterations that provide a selective advantage during melanoma progression. They play an important role in the development of drug resistance, including resistance to targeted therapies and immunotherapies. Distinct profiles of miRNA expression are detected at each step of melanoma development. Since miRNAs can be detected in liquid biopsies, they are considered biomarkers of early disease stages or response to treatment. This review summarizes recent findings regarding the role of miRNAs in melanoma metastasis.

Dicer1 is required for pigment cell and craniofacial development in zebrafish

The multidomain RNase III endoribonuclease DICER is required for the generation of most functional microRNAs (miRNAs). Loss of Dicer affects developmental processes at different levels. Here, we characterized the zebrafish Dicer1 mutant, dicer1^sa9205, which has a single point mutation induced by N-ethyl-N-nitrosourea mutagenesis. Heterozygous dicer1^sa9205 developed normally, being phenotypically indistinguishable from wild-type siblings. Homozygous dicer1^sa9205 mutants display smaller eyes, abnormal craniofacial development and aberrant pigmentation. Reduced numbers of both iridophores and melanocytes were observed in the head and ventral trunk of dicer1^sa9205 homozygotes; the effect on melanocytes was stronger and detectable earlier in development. The expression of microphthalmia-associated transcription factor a (mitfa), the master gene for melanocytes differentiation, was enhanced in dicer1-depleted fish. Similarly, the expression of SRY-box containing gene 10 (sox10), required for mitfa activation, was higher in mutants than in wild types. In silico and in vivo analyses of either sox10 or mitfa 3'UTRs revealed conserved potential miRNA binding sites likely involved in the post-transcriptional regulation of both genes. Based on these findings, we propose that dicer1 participates in the gene regulatory network governing zebrafish melanocyte differentiation by controlling the expression of mitfa and sox10.

miR-625-5p/PKM2 negatively regulates melanoma glycolysis state

PKM2 plays an important role in cancer glycolysis, however, the link of PKM2 and microRNAs (miRNAs) in melanoma is still unclear. The study will investigate the role of miRNAs in regulating PKM2 mediated melanoma cell glycolysis. We found that high PKM2 expression in melanoma tissues and cell lines was positively associated with glycolysis. Further study indicated that miR-625-5p regulated PKM2 expression on mRNA and protein levels in melanoma cells. There was a negative relationship between miR-625-5p and PKM2 expression in the clinical melanoma samples. These findings provide an evidence that miR-625-5p/PKM2 plays a role in melanoma cell glucose metabolism.

MicroRNA-143-3p inhibits growth and invasiveness of melanoma cells by targeting cyclooxygenase-2 and inversely correlates with malignant melanoma progression

Malignant melanoma is one of the most leading form of skin cancer associated with a low patient survival rate. Increasing evidence revealed that microRNAs (miRNAs) play a crucial role in the occurrence and development of several form of cancer including melanoma. In this study, we aimed at investigating the expression and role of miR-143-3p in human malignant melanoma. Our results showed that the expression of miR-143-3p was lower in human melanoma cells, as well as human biopsy specimens, when compared to normal human melanocytes. Ectopic expression of miR-143-3p in human melanoma cells inhibited proliferation, migration, invasion and promoted apoptosis acting through a molecular mechanism that, at least in part, is dependent on inhibition of cyclooxygenase-2 (COX-2) gene. Collectively, these results demonstrate that miR-143-3p could represent at the same time, a new early diagnostic marker and therapeutic target acting as tumor suppressor in melanoma cancer.

miR‑590‑5p inhibits tumor growth in malignant melanoma by suppressing YAP1 expression

The microRNAs (miRNAs/miRs) involved in the carcinogenesis and progression of malignant melanoma (MM) remain unclear. In the present study, miR-590-5p was identified to be upregulated in MM cells compared with human melanocytes using a reverse transcription-quantitative polymerase chain reaction to screen established oncogenic and tumor suppressor miRNAs. miR-590-5p was demonstrated to inhibit the cell proliferation and tumor growth of MM cells in vitro and in vivo by performing Cell Counting Kit-8 and tumour xenograft assays, respectively. In addition, flowcytometry assays indicated that miR-590-5p induced cell apoptosis and cell cycle arrest at the G1 stage in MM cells. Finally, luciferase assays and western blot analysis results confirmed that the transcriptional regulator Yes-associated protein 1 (YAP1) is upregulated and inversely associated with miR-590-5p expression in MM cells, and is the direct target and functional mediator of miR-590-5p in MM. Altogether these results reveal the functional and mechanistic link between miR-590-5p and YAP1 in the progression of MM. Therefore, miR-590-5p is a potential therapeutic target in MM.

miR‑30a‑5p inhibits the proliferation, migration and invasion of melanoma cells by targeting SOX4

MicroRNA (miR)‑30a‑5p has been reported to suppress the progression of hepatocellular cancer, renal cell carcinoma, oral cancer and gastric cancer. However, whether miR‑30a‑5p is involved in the regulation of melanoma remains unclear. The present study revealed that miR‑30a‑5p was downregulated in melanoma tissues and cell lines. Overexpression of miR‑30a‑5p significantly inhibited the proliferation, migration and invasion of melanoma cells in vitro. In addition, ectopic expression of miR‑30a‑5p delayed tumor growth in vivo. In terms of mechanism, miR‑30a‑5p targeted sex determining region Y‑box 4 (SOX4) and impeded the expression of SOX4 in melanoma cells. In addition, SOX4 was upregulated in melanoma tissues and cell lines when compared with normal tissues or cells. Furthermore, overexpression of SOX4 significantly rescued the proliferation, migration and invasion of melanoma cells transfected with miR‑30a‑5p mimics. Taken together, the results of the present study demonstrated that miR‑30a‑5p suppressed the proliferation, migration and invasion of melanoma cells in SOX4‑dependent manner.

MicroRNAs in cutaneous melanoma: Role as diagnostic and prognostic biomarkers

Melanoma is the leading cause of skin cancer deaths in the United States, and its incidence has been rising steadily for the past 30 years (Aftab, Dinger, & Perera, 2014). A more complete understanding of the molecular mechanisms that drive melanomagenesis is crucial to improve diagnosis, prognostication, and treatment of this disease. Given that melanoma survival rates are better when the disease is detected early, precise diagnostic tests for early melanoma detection would be extremely useful. In addition, as survival rates decrease drastically when the disease becomes metastatic, improved tools to more precisely identify high-risk patients as well as to predict treatment response are necessary. The role of microRNAs (miRNAs) in melanoma biology could be the key. miRNA expression profiling has identified several miRNAs that play a crucial role in melanoma cell proliferation, migration, and invasion, as well as miRNAs involved in apoptosis and in the immune response. Here we review the most current data on the miRNAs involved in melanoma as well as their potential roles as diagnostic and prognostic biomarkers of this disease.

MicroRNA-365 Inhibits Cell Growth and Promotes Apoptosis in Melanoma by Targeting BCL2 and Cyclin D1 (CCND1)

BACKGROUND MicroRNA-365 (miR-365) is involved in the development of a variety of cancers. However, it remains largely unknown if and how miRNAs-365 plays a role in melanoma development. MATERIAL AND METHODS In this study, we overexpressed miR-365 in melanoma cell lines A375 and A2058, via transfection of miR-365 mimics oligos. We then investigated alterations in a series of cancer-related phenotypes, including cell viability, cell cycle, apoptosis, colony formation, and migration and invasion capacities. We also validated cyclin D1 (CCND1) and BCL2 apoptosis regulator (BCL2) as direct target genes of miR-365 by luciferase reporter assay and investigated their roles in miR-365 caused phenotypic changes. To get a more general view of miR-365's biological functions, candidate target genes of miR-365 were retrieved via searching online databases, which were analyzed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses for potential biological functions. We then analyzed The Cancer Genome Atlas (TCGA) Skin Cutaneous Melanoma (SKCM) dataset for correlation between miR-365 level and clinicopathological features of patients, and for survival of patients with high and low miR-365 levels. RESULTS We found that miR-365 was downregulated in melanoma cells. Overexpression of miR-365 remarkably suppressed cell proliferation, induced cell cycle arrest and apoptosis, and compromised the migration and invasion capacities in A375 and A2058 cell lines. We also found that the phenotypic alterations by miR-365 were partially due to downregulation of CCND1 and BCL2 oncogenes. The bioinformatics analysis revealed that predicted targets of miR-365 were widely involved in transcriptional regulation and cancer-related signaling pathways. However, analysis of SKCM dataset failed to find differences in miR-365 level among melanoma patients at different clinicopathologic stages. The Kaplan-Meier analysis also failed to discover significant differences in overall survival and disease-free survival between patients with high and low miR-365 levels. CONCLUSIONS Our findings suggested that miR-365 might be an important novel regulator for melanoma formation and development, however, the in vivo roles in melanoma developments need further investigation.

Circulating MicroRNA Biomarkers in Melanoma: Tools and Challenges in Personalised Medicine

Effective management of melanoma depends heavily on early diagnosis. When detected in early non-metastatic stages, melanoma is almost 100% curable by surgical resection, however when detected in late metastatic stages III and IV, 5-year survival rates drop to ~50% and 10–25%, respectively, due to limited efficacy of current treatment options. This presents a pressing need to identify biomarkers that can detect patients at high risk of recurrence and progression to metastatic disease, which will allow for early intervention and survival benefit. Accumulating evidence over the past few decades has highlighted the potential use of circulating molecular biomarkers for melanoma diagnosis and prognosis, including lactate dehydrogenase (LDH), S100 calcium-binding protein B (S100B) and circulating tumor DNA (ctDNA) fragments. Since 2010, circulating microRNAs (miRNAs) have been increasingly recognised as more robust non-invasive biomarkers for melanoma due to their structural stability under the harsh conditions of the blood and different conditions of sample processing and isolation. Several pre-analytical and analytical variables challenge the accurate quantification of relative miRNA levels between serum samples or plasma samples, leading to conflicting findings between studies on circulating miRNA biomarkers for melanoma. In this review, we provide a critical summary of the circulating miRNA biomarkers for melanoma published to date.

Integrated Analysis Reveals That miR-193b, miR-671, and TREM-1 Correlate With a Good Response to Treatment of Human Localized Cutaneous Leishmaniasis Caused by Leishmania braziliensis

Localized cutaneous leishmaniasis (LCL) is a chronic disease characterized by ulcerated skin lesion(s) and uncontrolled inflammation. The mechanisms underlying the pathogenesis of LCL are not completely understood, and little is known about posttranscriptional regulation during LCL. MicroRNAs (miRNAs) are non-coding small RNAs that regulate gene expression and can be implicated in the pathogenesis of LCL. We investigated the involvement of miRNAs and their targets genes in human LCL using publicly available transcriptome data sets followed by ex vivo validation. Initial analysis highlighted that miRNA expression is altered during LCL, as patients clustered separately from controls. Joint analysis identified eight high confidence miRNAs that had altered expression (−1.5 ≤ fold change ≥ 1.5; p < 0.05) between cutaneous ulcers and uninfected skin. We found that the expression of miR-193b and miR-671 are greatly associated with their target genes, CD40 and TNFR, indicating the important role of these miRNAs in the expression of genes related to the inflammatory response observed in LCL. In addition, network analysis revealed that miR-193b, miR-671, and TREM1 correlate only in patients who show faster wound healing (up to 59 days) and not in patients who require longer cure times (more than 60 days). Given that these miRNAs are associated with control of inflammation and healing time, our findings reveal that they might influence the pathogenesis and prognosis of LCL.

Integrative analysis of competing endogenous RNA network focusing on long noncoding RNA associated with progression of cutaneous melanoma

Cutaneous melanoma (CM) is the most malignant tumor of skin cancers because of its rapid development and high mortality rate. Long noncoding RNAs (lncRNAs), which play essential roles in the tumorigenesis and metastasis of CM and interplay with microRNAs (miRNAs) and mRNAs, are hopefully considered to be efficient biomarkers to detect deterioration during the progression of CM to improve the prognosis. Bioinformatics analysis was fully applied to predict the vital lncRNAs and the associated miRNAs and mRNAs, which eventually constructed the competing endogenous RNA (ceRNA) network to explain the RNA expression patterns in the progression of CM. Further statistical analysis emphasized the importance of these key genes, which were statistically significantly related to one or few clinical features from the ceRNA network. The results showed the lncRNAs MGC12926 and LINC00937 were verified to be strongly connected with the prognosis of CM patients.

MicroRNA-Directed Cancer Therapies: Implications in Melanoma Intervention

Acquired tumor resistance to cancer therapies poses major challenges in the treatment of cancers including melanoma. Among several signaling pathways or factors that affect neocarcinogenesis, cancer progression, and therapies, altered microRNAs (miRNAs) expression has been identified as a crucial player in modulating the key pathways governing these events. While studies in the miRNA field have grown exponentially in the last decade, much remains to be discovered, particularly with respect to their roles in cancer therapies. Since immune and nonimmune signaling cascades prevail in cancers, identification and evaluation of miRNAs, their molecular mechanisms and cellular targets involved in the underlying development of cancers, and acquired therapeutic resistance would help in devising new strategies for the prognosis, treatment, and an early detection of recurrence. Importantly, in-depth validation of miRNA-targeted molecular events could lead to the development of accurate progression-risk biomarkers, improved effectiveness, and improved patient responses to standard therapies. The current review focuses on the roles of miRNAs with recent updates on regulated cell cycle and proliferation, immune responses, oncogenic/epigenetic signaling pathways, invasion, metastasis, and apoptosis, with broader attention paid to melanomagenesis and melanoma therapies.

Age-related common miRNA polymorphism associated with severe toxicity in lung cancer patients treated with platinum-based chemotherapy

Platinum-based chemotherapy toxicity severely impedes successful treatment in lung cancer patients. MicroRNAs (miRs) have a significant impact on the occurrence and survival rate of lung cancer. The purpose of this study was to investigate the association between common miRNA variants and platinum-based chemotherapy toxicity in lung cancer patients. A total of eight functional single nucleotide polymorphisms (SNPs) of miRNA were genotyped in 408 lung cancer patients by MALDI-TOF mass spectrometry. All the patients were histologically confirmed as lung cancer, and were treated with platinum-based chemotherapy for at least two cycles. It was found that the polymorphism rs2042553 of miR-5197 had a significant association with overall severe toxicity in both additive (P=.031, odds ratio [OR]=1.41, 95% confidence interval [CI] 1.03-1.93) and dominant (P=.009, OR=1.80, 95% CI 1.16-2.80) models. MiR-605 rs2043556 was significantly related to severe hepatotoxicity in dominant model (P=.022, OR=2.51, 95% CI 1.12-4.14). In addition, rs2910164 of miR-146a had marginal statistical effect on severe hepatotoxicity in additive model (P=.054). The subgroup analyses showed that miR-27a rs895819 was related to gastrointestinal toxicity in age >56 years old, smoking and non-smoking patients. Taken together, our results revealed that polymorphisms of miR-5197, miR-605, miR-146a, and miR-27a contributed to the chemotherapy toxicity of lung cancer, which may serve as a predictive tool for toxicity evaluation of platinum-based chemotherapy in lung cancer patients.

Low expression of microRNA-320b correlates with tumorigenesis and unfavorable prognosis in glioma

Accumulating evidence demonstrates that dysregulated microRNAs (miRNAs) play a critical role in tumorigenesis and progression of various cancers. miR-320b, a member of miR‑320 family, was revealed downregulated in numerous human cancers, including nasopharyngeal carcinoma and colorectal cancer. However, the function of miR‑320b in human glioma remained poorly defined. In this study, we report that miR‑320b was lowly expressed in glioma tissues and cell lines in contrast with controls, being closely correlated with histological malignancy of glioma. Furthermore, patients with low expression of miR‑320b were associated with poor prognostic outcomes. In vitro functional assays indicated that overexpression of miR‑320b could markedly enhance cell apoptosis rate and suppress cell proliferation, migration and invasion. miR-320b mimic impaired cell cycle and metastasis through inhibiting the expression of G1/S transition key regulator Cyclin D1 as well as decreasing the expression level of MMP2 and MMP9. Additionally, upregulation of miR‑320b could markedly promote apoptosis by increasing the level of Bax and reducing Bcl-2 expression in glioma. Taken together, our data suggested that miR‑320b might serve as a novel prognostic marker and potential therapeutic target for glioma.

Circulating microRNA-194 regulates human melanoma cells via PI3K/AKT/FoxO3a and p53/p21 signaling pathway

In the present study, we analyzed the role of microRNA-194 circulating regulated human melanoma cell growth. We found that microRNA-194 expression was markedly suppressed in human melanoma patients, compared with negative control group. Next, disease-free survival (DFS) and overall survival (OS) of high expression in human melanoma patients was higher than those of low expression in human melanoma patients. MicroRNA-194 overexpression inhibited cell proliferation, induced apoptosis, increased caspase-3/-9 activities and promoted Bax/Bcl-2 of human melanoma cells. Furthermore, microRNA-194 overexpression also suppressed PI3K/AKT/FoxO3a signaling pathway and induced p53/p21 signaling pathway. PI3K inhibitor, suppressed PI3K, phosphorylation-AKT, FoxO3a protein expression and increased the effects of microRNA-194 overexpression on cell growth, apoptosis, caspase-3/-9 activities and Bax/Bcl-2 protein expression of human melanoma cells through the induction of p53/p21 signaling pathway. Taken together, these data indicate that circulating microRNA-194 regulated human melanoma cells via PI3K/AKT/FoxO3a and p53/p21 signaling pathway.

Deep Illumina sequencing reveals conserved and novel microRNAs in grass carp in response to grass carp reovirus infection

Background

The grass carp hemorrhagic disease caused by the grass carp reovirus (GCRV) is a major disease that hampers the development of grass carp aquaculture. The mechanism underlying GCRV pathogenesis and hemorrhagic symptoms is still unknown. MicroRNAs (miRNAs) are key regulators involved in various biological processes. The aim of this study was to identify conserved and novel miRNAs in grass carp in response to GCRV infection, as well as attempt to reveal the mechanism underlying GCRV pathogenesis and hemorrhagic symptoms.

Results

Grass carp were infected with GCRV, and spleen samples were collected at 0 (control), 1, 3, 5, 7, and 9 days post-infection (dpi). These samples were used to construct and sequence small RNA libraries. A total of 1208 miRNAs were identified, of which 278 were known miRNAs and 930 were novel miRNAs. Thirty-six miRNAs were identified to exhibit differential expression when compared with the control, and 536 target genes were predicted for the 36 miRNAs. GO and KEGG enrichment analyses of these target genes showed that many of the significantly enriched terms were associated with immune response, blood coagulation, hemostasis, and complement and coagulation cascades, especially the GO term “blood coagulation” and pathway “complement and coagulation cascades.” Ten representative target genes involved in “complement and coagulation cascades” were selected for qPCR analysis, and the results showed that the expression patterns of these target genes were significantly upregulated at 7 dpi, suggesting that the pathway “complement and coagulation cascades” was strongly activated.

Conclusion

Conserved and novel miRNAs in response to GCRV infection were identified in grass carp, of which 278 were known miRNAs and 930 were novel miRNAs. Many of the target genes involved in immune response, blood coagulation, hemostasis, and complement and coagulation cascades. Strong activation of the pathway “complement and coagulation cascades” may have led to endothelial-cell and blood-cell damage and hemorrhagic symptoms. The present study provides a new insight into understanding the mechanism underlying GCRV pathogenesis and hemorrhagic symptoms.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-017-3562-4) contains supplementary material, which is available to authorized users.

MicroRNAs miR-7 and miR-340 predict response to neoadjuvant chemotherapy in breast cancer

PURPOSE

miRNAs have been linked to chemosensitivity of breast cancer cells in vitro. In patients, however, there is no clinically validated method for predicting chemotherapy response. The aim of this study was to assess whether (I) a specific pattern of miRNA expression in pretherapeutic biopsies can predict response to neoadjuvant chemotherapy, and (II) differential miRNA expression in residual tumor after completion of chemotherapy allows further prognostic stratification of non-responding patients.

METHODS

Sixty-four patients with newly diagnosed large (≥3 cm) or locally advanced primary breast cancers who underwent neoadjuvant anthracycline/taxane-based chemotherapy were included. Relative expression of 10 miRNAs likely to be associated with chemotherapy response (miR-7,-21,-29a,-29b,-34a,-125b,-155,-200c,-340,-451) was determined by quantitative RT-PCR from pretherapeutic biopsies (n = 64) and residual invasive tumor after chemotherapy (n = 42). Pathologic complete response (pCR) defined by absence of invasive tumor served as reference standard. In addition, miRNA expression was compared with disease-free and overall survival.

RESULTS

Nine (14%) of 64 patients achieved pCR. High expression of miR-7 and low expression of miR-340 in pretherapeutic biopsies predicted pCR with a negative predictive value of 96 and 97%, respectively (specificity 54 and 57%). The combined profile of miR-7^high/miR-340^low demonstrated improved specificity of 86% while maintaining a high negative predictive value (96%) to identify non-responders. Pretherapeutic expression of miR-200c and miR-155 showed prognostic information, and low expression was associated with increased overall survival (115 vs. 90 months, p ≤ 0.03). After chemotherapy, the overall survival of patients with residual invasive tumor was better for those demonstrating low miR-7 or high miR-125b (p = 0.01).

CONCLUSIONS

Intratumoral expression of miR-7 and miR-340 prior to neoadjuvant chemotherapy could be used to predict pCR and a profile of miR-7^low or miR-340^high identified patients unlikely to achieve pCR who might benefit from alternative treatment options including earlier surgery. Our study identifies miRNAs as promising predictive biomarkers, which could aid in optimization of breast cancer management and treatment stratification.