MicroRNA dysregulation 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.

A Tumor and Immune-Related Micro-RNA Signature Predicts Relapse-Free Survival of Melanoma Patients Treated with Ipilimumab

Despite the unprecedented advances in the treatment of melanoma with immunotherapy, there continues to be a major need for biomarkers of clinical benefits and immune resistance associated with immune checkpoint inhibitors; microRNA could play a vital role in these efforts. This study planned to identify differentially expressed miRNA molecules that may have prognostic value for clinical benefits. Patients with surgically operable regionally advanced melanoma were treated with neoadjuvant ipilimumab (10 mg/kg intravenously every 3 weeks × two doses) bracketing surgery. Tumor biospecimens were obtained at baseline and surgery, and microRNA (miRNA) expression profiling was performed on the tumor biopsies. We found that an expression profile consisting of a 4-miRNA signature was significantly associated with improved relapse-free survival (RFS). The signature consisted of biologically relevant molecules previously reported to have prognostic value in melanoma and other malignancies, including miR-34c, miR-711, miR-641, and miR-22. Functional annotation analysis of target genes for the 4-miRNA signature was significantly enriched for various cancer-related pathways, including cell proliferation regulation, apoptosis, the MAPK signaling pathway, and the positive regulation of T cell activation. Our results presented miRNAs as potential biomarkers that can guide the treatment of melanoma with immune checkpoint inhibitors. These findings warrant further investigation in relation to CTLA4 blockade and other immune checkpoint inhibitors. ClinicalTrials.gov NCT00972933.

MicroRNA-155 and Disease-Related Immunohistochemical Parameters in Cutaneous Melanoma

Cutaneous melanoma is a severe and life-threatening form of skin cancer with growing incidences. While novel interventions have improved prognoses for these patients, early diagnosis of targeted treatment remains the most effective approach. MicroRNAs have grown to good use as potential biomarkers for early detection and as targets for treatment. miR-155 is well-studied for its role in tumor cell survival and proliferation in various tissues, although its role in melanoma remains controversial. In silico data analysis was performed in the dbDEMC v.3 to identify differentially expressed miRNA. We validated gene targets in melanoma using TarBase v8.0 and miRPath v3.0 and determined protein-protein interactions of the target genes. One hundred forty patients (age range 21-90 years) with cutaneous melanoma who underwent resection were included. Molecular assessment using Real-Time RT-qPCR, clinicopathological associations, and a literature review for the different roles of miR-155 in melanoma were performed. Analysis of the dbDEMC reveals controversial findings. While there is evidence of upregulation of miR-155 in primary and metastatic melanoma samples, others suggest decreased expression in later-stage melanoma and cases with brain metastasis. miR-155 has been overexpressed in prior cases of melanoma and precancerous lesions, and it was found to be dysregulated when compared to benign nevi. While miR-155 expression was associated with favorable outcomes in some studies, others showed an association with metastasis. Patients with high levels of miR-155 also noted reduction after receiving anti-PD-1 treatment, correlated with more prolonged overall survival. In our patient's cohort, 22.9% relapsed during treatment, and 45% developed recurrence, associated with factors such as lymph node infiltration, high mitotic index, and positive staining for CD117. Although overall analysis revealed miR-155 downregulation in melanoma specimens compared to non-cancer tissues, increased expression of miR-155 was associated with cases of superficial spreading melanoma subtype (p = 0.005) and any melanoma with a high mitotic rate (p = 0.010). The analysis did not identify optimum cutoff values to predict relapse, recurrence, or mortality. In conclusion, miR-155 could have, in part, a potential prognostic utility in cutaneous melanoma. Further mechanistic studies are required to unravel the multifunctional role of miR-155 in melanoma.

Curcumin Inhibits the Growth and Metastasis of Melanoma via miR-222-3p/SOX10/Notch Axis

Background

The aim of this study was to investigate the effect of curcumin on melanoma and its mechanism.

Methods

Curcumin (0, 0.125, 0.25, or 0.5 mg/ml) was utilized to treat A375 and HT144 cell lines. The MTT analysis was used to confirm the proliferation ability. Wound healing and transwell analysis showed the migration and invasion ability. Immunofluorescence assay was used to demonstrate the effect of curcumin on SOX10 expression. Multiple bioinformatic analysis to confirm the SOX10 associated miRNA. The correlation of miR-222-3p and SOX10 was detected by Luciferase reporter assays. qRT-PCR showed the miR-222-3p level. Western blot analyzed the expression of SOX10, Notch1, and HES1 in melanoma cell treated with or without miR-222-3p inhibitor.

Results

Curcumin could inhibit the proliferation, migration, and invasion of melanoma cells. Furthermore, curcumin repress the expression of SOX10, Notch1, and HES-1, and increase the expression of miR-222-3p. And the miR-222-3p could directly target to SOX10 mRNA to inhibit its expression. In addition, inhibition of miR-222-3p expression reversed the inhibitory effect of curcumin the growth of melanoma cells.

Conclusion

Curcumin enhances the miR-222-3p level to reduce SOX10 expression, and ultimately inactivates the Notch pathway in repressing melanoma proliferation, migration, and invasion.

Prognostic Value of IGF2 mRNA-Binding Protein 3 (IGF2BP3) Intratumoral Expression in Melanoma Patients at the Time of Diagnosis: Comparative Analysis of RT-qPCR Versus Immunohistochemistry

Simple Summary

Around 80% of skin cancer deaths are due to melanoma. An accurate prognosis of melanoma clinical behavior from primary tumors is important for therapeutic patient management, currently based on histopathological features. The aim of our retrospective study was to investigate the clinical significance of IGF2BP3 mRNA and protein expression in melanoma progression and to evaluate which quantification method, RT-qPCR or immunohistochemistry, provides a more reliable prognostic value of IGF2BP3 expression in primary tumors. We found that IGF2BP3 mRNA expression correlated better with clinicopathologic melanoma features than the corresponding proteins and that patients with higher IGF2BP3 mRNA levels were at more risk for earlier development of metastasis, confirming its impact on melanoma survival. Our findings support the use of IGF2BP3 mRNA levels as an independent prognostic biomarker and the implementation of its RT-qPCR analysis for routine melanoma assessment, even for the earliest stages, to improve melanoma clinical outcomes and individualized treatment.

Abstract

Screening for prognostic biomarkers is crucial for clinical melanoma management. Insulin-like growth factor-II mRNA-binding protein 3 (IGF2BP3) has emerged as a potential melanoma diagnostic and prognostic biomarker. It is commonly tested by immunohistochemistry (IHC). Our study retrospectively examines IGF2BP3 mRNA and protein expression in primary melanomas, their correlation with clinicopathologic factors, clinical outcome, and selected miRNAs expression, and their efficiency in predicting melanoma progression and survival. RT-qPCR and IHC on IGF2BP3 expression were performed in 61 cryopreserved and 63 formalin-fixed paraffin-embedded primary melanomas, respectively, and correlated to clinicopathologic factors, distant metastasis-free survival (DMFS), and melanoma -specific survival (MSS). The correlation between RT-qPCR and IHC was significant but moderate. IGF2BP3 mRNA showed a stronger association with clinicopathologic factors (Breslow thickness, ulceration, mitosis rate, growth phase, development of metastasis, and melanoma-specific survival) than its protein counterpart. Interestingly, higher IGF2BP3 mRNA expression was detected in primary melanomas that further metastasized to distant sites and was an independent prognostic factor for the risk of unfavorable DMFS and MSS. RT-qPCR outperformed IHC in sensitivity and in predicting worse clinical outcomes. Therefore, RT-qPCR may successfully be implemented for routine IGF2BP3 assessing for the selection of melanoma patients with a higher risk of developing distant metastasis and dying of melanoma.

Liquid Biopsy and Dielectrophoretic Analysis—Complementary Methods in Skin Cancer Monitoring

The incidence and prevalence of skin cancers is currently increasing worldwide, with early detection, adequate treatment, and prevention of recurrences being topics of great interest for researchers nowadays. Although tumor biopsy remains the gold standard of diagnosis, this technique cannot be performed in a significant proportion of cases, so that the use of alternative methods with high sensitivity and specificity is becoming increasingly desirable. In this context, liquid biopsy appears to be a feasible solution for the study of cellular and molecular markers relevant to different types of skin cancers. Circulating tumor cells are just one of the components of interest obtained from performing liquid biopsy, and their study by complementary methods, such as dielectrophoresis, could bring additional benefits in terms of characterizing skin tumors and subsequently applying personalized therapy. One purpose of this review is to demonstrate the utility of liquid biopsy primarily in monitoring the most common types of skin tumors: basal cell carcinoma, squamous cell carcinoma, and malign melanoma. In addition, the originality of the article is based on the detailed presentation of the dielectrophoretic analysis method of the most important elements obtained from liquid biopsy, with direct impact on the clinical and therapeutic approach of skin tumors.

The Prognostic Value of miR-125b, miR-200c and miR-205 in Primary Cutaneous Malignant Melanoma Is Independent of BRAF Mutational Status

Simple Summary

Melanoma accounts for the majority of skin cancer-related deaths. On the one hand, most melanomas contain mutations in the BRAF gene (predominantly V600E), and on the other hand, miRNAs modulate different steps in melanoma development and progression, but there are no reports that study the relation between BRAF mutational status and the expression of miRNAs, which is important for an accurate patient prognosis. The aim of our retrospective study was to know whether BRAF mutations influence the prognostic value of miR-125b, miR-200c and miR-205 intratumoral expression in primary cutaneous melanomas. Globally, our results showed that miR-125b, miR-200c and miR-205 expression predicted the clinical outcome of primary melanomas independently of BRAF status. Thus, our findings support that BRAF mutations alone do not predict the risk of metastasis development or melanoma survival and that miR-125b, miR-200c and miR-205 may be considered as accurate prognostic biomarkers in melanoma regardless of BRAF mutational status.

Abstract

BRAF mutations are present in around 50% of cutaneous malignant melanomas and are related to a poor outcome in advanced-stage melanoma patients. miRNAs are epigenetic regulators that modulate different cellular processes in cancer, including melanoma development and progression. However, there are no studies on the potential associations of the genetic alterations of the BRAF gene with miRNA expression in primary cutaneous melanomas. Here, in order to analyze the influence of BRAF mutations in the ability of selected miRNAs to predict clinical outcome and patient survival at the time of diagnosis, we studied the prognostic value of miR-125b, miR-200c and miR-205 expression depending on the BRAF mutational status in fresh, frozen primary tumor specimens. For this purpose, RNA was extracted for studying both BRAF mutations by Sanger sequencing and miRNA expression. Our results indicate that, although there seems to be a slight preference for their predictive ability in the BRAF mutated group, the expression of these three miRNAs serves effectively to predict the clinical outcome of melanoma patients independently of BRAF mutational status at the time of primary tumor diagnosis.

BRAFV600E induces reversible mitotic arrest in human melanocytes via microrna-mediated suppression of AURKB

Benign melanocytic nevi frequently emerge when an acquired BRAFV600E mutation triggers unchecked proliferation and subsequent arrest in melanocytes. Recent observations have challenged the role of oncogene-induced senescence in melanocytic nevus formation, necessitating investigations into alternative mechanisms for the establishment and maintenance of proliferation arrest in nevi. We compared the transcriptomes of melanocytes from healthy human skin, nevi, and melanomas arising from nevi and identified a set of microRNAs as highly expressed nevus-enriched transcripts. Two of these microRNAs-MIR211-5p and MIR328-3p-induced mitotic failure, genome duplication, and proliferation arrest in human melanocytes through convergent targeting of AURKB. We demonstrate that BRAFV600E induces a similar proliferation arrest in primary human melanocytes that is both reversible and conditional. Specifically, BRAFV600E expression stimulates either arrest or proliferation depending on the differentiation state of the melanocyte. We report genome duplication in human melanocytic nevi, reciprocal expression of AURKB and microRNAs in nevi and melanomas, and rescue of arrested human nevus cells with AURKB expression. Taken together, our data describe an alternative molecular mechanism for melanocytic nevus formation that is congruent with both experimental and clinical observations.

Loss of miR-1469 expression mediates melanoma cell migration and invasion

Tumor ulceration is considered one of the most prognostically significant findings in primary cutaneous melanoma, associated with decreased disease-free and overall survival. However, the unique features associated with ulcerated melanoma that contribute to a poor prognosis in affected patients remain poorly defined. microRNAs are small, non-coding RNAs that function to inhibit expression of specific gene targets, therefore altering the functions of cells in which they are expressed. miR-1469 is a novel miR with significantly decreased expression in ulcerated melanoma tissue relative to non-ulcerated tumors. We hypothesized that loss of miR-1469 expression in melanoma contributes to altered tumor cell functions mediating disease progression. Transfection of a miR-1469 mimic resulted in a significant reduction in the migratory and invasive capacity of the CHL1 and MEL39 melanoma cell lines (>58.1% reduction, p < 0.0332), as well as the invasive capacity of the A375 melanoma cell line (>50% reduction, p < 0.0021). Expression of myeloid cell leukemia-1 (MCL1), a miR-1469 target gene, was reduced in the A375 and MEL39 cell lines by immunoblot. No significant differences in viability, resistance to apoptotic stimuli, or proliferation were observed following transfection. These findings together demonstrate how migration and invasion are specific functions through which miR-1469 expression in melanoma cells can contribute to the differences in disease progression associated with tumor ulceration.

Up-regulation of KISS1 as a novel target of Let-7i in melanoma serves as a potential suppressor of migration and proliferation in vitro

Melanoma is a kind of skin cancer that is begun by the alteration of melanocytes. miRNAs are small non-coding RNA molecules that regulate a variety of biological processes. KISS1, the metastasis-suppressor gene, encodes kisspeptins which inhibits migration and proliferation of cancers. This study was aimed to determine the role of Let-7i and KISS1 in melanoma cell migration and proliferation. At first, the expression of Let-7i and KISS1 was determined in patients with melanoma. In the in vitro part of the study, Let-7i mimics were transfected and the impact of its restoration on target gene expression, proliferation, migration and apoptosis of SK-MEL-3 melanoma cell line was assessed by real-time PCR and Western blotting, MTT assay, wound-healing assay and flow cytometry, respectively. Besides, KISS1 inhibitor siRNA alone and along with Let-7i was transfected to determine their probable correlation. The results revealed that either Let-7i or KISS1 were down-regulated in patients with melanoma. The results obtained from the in vitro part of the study revealed that restoration of Let-7i reduced the expression of metastasis- and proliferation-related target genes. Moreover, it was revealed that up-regulation of Let-7i attenuated migration and proliferation capability of SK-MEL-3 cells. Besides, it was demonstrated that Let-7i restoration induced apoptosis in melanoma cells. More importantly, the KISS1 inhibitor caused a prominent cell migration and proliferation, attenuated by Let-7i re-expression. To sum up, the present study revealed the impressive role of Let-7i restoration along with its correlation with KISS1 on melanoma carcinogenicity which may be applicable in future in vivo studies.

Prognostic and Predictive Biomarkers in Stage III Melanoma: Current Insights and Clinical Implications

Melanoma is one of the most aggressive skin cancers. The 5-year survival rate of stage III melanoma patients ranges from 93% (IIIA) to 32% (IIID) with a high risk of recurrence after complete surgery. The introduction of target and immune therapies has dramatically improved the overall survival, but the identification of patients with a high risk of relapse who will benefit from adjuvant therapy and the determination of the best treatment choice remain crucial. Currently, patient prognosis is based on clinico-pathological features, highlighting the urgent need of predictive and prognostic markers to improve patient management. In recent years, many groups have focused their attention on identifying molecular biomarkers with prognostic and predictive potential. In this review, we examined the main candidate biomarkers reported in the literature.

MiR-211 protects cerebral ischemia/reperfusion injury by inhibiting cell apoptosis

MicroRNAs (miRNAs) have emerged as critical regulators of neuronal survival during cerebral ischemia/reperfusion injury. Accumulating evidence has shown that miR-211 plays a crucial role in regulating apoptosis and survival in various cell types. However, whether miR-211 is involved in regulating neuronal survival during cerebral ischemia/reperfusion injury remains unknown. In this study, we aimed to explore the biological role of miR-211 in regulating neuronal injury induced by oxygen-glucose deprivation/reoxygenation (OGD/R) and transient cerebral ischemia/reperfusion (I/R) injury in vitro and in vivo. We found that miR-211 expression was significantly downregulated in PC12 cells in response to OGD/R and in the penumbra of mouse in response to MCAO. Overexpression of miR-211 alleviated OGD/R-induced PC12 cell apoptosis, whereas miR-211 inhibition facilitated OGD/R-induced PC12 cell apoptosis in vitro. Moreover, overexpression of miR-211 reduced infarct volumes, neurologic score, and neuronal apoptosis in vivo, whereas miR-211 inhibition increased infarct volumes, neurologic score and neuronal apoptosis in vivo. Notably, our results identified P53-up-regulated modulator of apoptosis (PUMA) as a target gene of miR-211. Our findings suggested that miR-211 may protect against MCAO injury by targeting PUMA in rats, which paves a potential new way for the therapy of cerebral I/R injury.

miR-143 acts as an inhibitor of migration and proliferation as well as an inducer of apoptosis in melanoma cancer cells in vitro

Melanoma is a serious form of skin cancers begins in the melanocyte. Micro-RNAs are small noncoding RNA with 19 to 25 nucleotides in length involves in the regulation of a wide range of biological processes. MicroRNAs are affected by an aberrant epigenetic alteration in the tumors that may lead to their dysregulation and formation of cancer. Recently, dysregulation of numerous microRNAs has been reported in different types of cancer. The present study focused on the role of miR-143 in carcinogenesis of melanoma cancer. Here, we evaluated the expression level of miR-143 in three melanoma cell lines in comparison with the normal human epidermal melanocyte cell line. Then, miR-143 gene plasmid transfected into the WM115 cell line, for having the lowest expression of miR-143. In addition, the effect of miR-143 transfection on mRNA and protein levels of metastasis-related genes was performed along with MTT assay, wound healing assay, and flow cytometry. The results showed that mRNA and protein expression levels of metastasis-related genes including MMP-9, E-cadherin, Vimentin, and CXCR4 have been reduced following transfection of miR-143. Moreover, the results of the scratch test showed that miR-143 re-expression inhibited cell migration. Also, the role of miR-143 in the induction of apoptosis and inhibition of proliferation by flow cytometry and MTT was confirmed. As a result, the present study showed that miR-143 was involved in metastatic and apoptotic pathways, suggesting that miR-143 acts as a tumor-suppressor microRNA in melanoma cancer.

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.

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.

Long Noncoding RNA PVT1 Silencing Prevents the Development of Uveal Melanoma by Impairing MicroRNA-17-3p-Dependent MDM2 Upregulation

Purpose

Uveal melanoma is a common primary intraocular malignancy accompanied by high mortality. Previous evidence has highlighted the implication of microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) in uveal melanoma. Accordingly, we further uncovered the possible role of lncRNA plasmacytoma variant translocation 1 gene (PVT1) and microRNA-17-3p (miR-17-3p) in uveal melanoma.

Methods

A series of experiments were performed to examine the relationship among lncRNA PVT1, miR-17-3p, and murine double minute clone 2 oncoprotein (MDM2). Afterward, gain- and loss-of-function approaches were used with uveal melanoma cells to verify the role of lncRNA PVT1, miR-17-3p, and MDM2 in the tumorigenesis and development of uveal melanoma.

Results

Highly expressed lncRNA PVT1 and MDM2, yet lowly expressed miR-17-3p, were identified in ocular uveal melanoma tissues versus normal adjacent tissues. Then, dual luciferase reporter gene assay, RNA binding protein immunoprecipitation, and RNA pull-down assays showed that lncRNA PVT1 specifically bound to miR-17-3p, and that MDM2 was a target gene of miR-17-3p. Gain- and loss-of-function studies elucidated that silencing of lncRNA PVT1 or overexpression of miR-17-3p resulted in decreased MDM2 expression and increased transcriptional activity of p53, in addition to inhibiting uveal melanoma cell proliferation, migration, and invasion, yet promoted cell apoptosis in vitro. In addition, lncRNA PVT1 silencing or miR-17-3p overexpression was noted to inhibit tumor growth in vivo.

Conclusions

Downregulation of lncRNA PVT1 could potentially promote miR-17-3p expression to suppress tumorigenesis and development of uveal melanoma by activating the p53 signaling pathway through binding to MDM2.

MicroRNA Ratios Distinguish Melanomas from Nevi

The use of microRNAs as biomarkers has been proposed for many diseases, including the diagnosis of melanoma. Although hundreds of microRNAs have been identified as differentially expressed in melanomas as compared to benign melanocytic lesions, a limited consensus has been achieved across studies, constraining the effective use of these potentially useful markers. In this study, we applied a machine learning-based pipeline to a dataset consisting of genetic features, clinical features, and next-generation microRNA sequencing from micro-dissected formalin-fixed paraffin embedded melanomas and their adjacent benign precursor nevi. We identified patient age and tumor cellularity as variables that frequently confound the measured expression of potentially diagnostic microRNAs. By employing the ratios of microRNAs that were either enriched or depleted in melanoma compared to the nevi as a normalization strategy, we developed a model that classified all the available published cohorts with an area under the receiver operating characteristic curve of 0.98. External validation on an independent cohort classified lesions with 81% sensitivity and 88% specificity and was uninfluenced by the tumor content of the sample or patient age.

Circulating microRNAs as biomarkers for early diagnosis of cutaneous melanoma

Introduction: Cutaneous melanoma is the deadliest form of skin cancer, with a dramatic increase in the incidence rate worldwide over the past decade. Early detection has been shown to improve the outcome of melanoma patients. The identification of noninvasive biomarkers able to identify melanoma at an early stage remains an unmet clinical need. Circulating miRNAs (c-miRNAs), small non-coding RNAs, appear as potential ideal candidate biomarkers due to their stability in biological fluids and easy detectability. Moreover, c-miRNAs are reported to be heavily deregulated in cancer patients.Areas covered: This review examines evidence of the specific c-miRNAs or panels of c-miRNAs reported to be useful in discriminating melanoma from benign cutaneous lesions.Expert opinion: Although the interesting reported by published studies, the non-homogeneity of detection and normalization methods prevents the individuation of single c-miRNA or panel of c-miRNAs that are specific for early detection of cutaneous melanoma. In the future, prospective wide and well-designed clinical trials will be needed to validate the diagnostic potential of some of the c-miRNA candidates in clinical practice.

MicroRNA Expression in Formalin-Fixed, Paraffin-Embedded Samples of Canine Cutaneous and Oral Melanoma by RT-qPCR

MicroRNAs (miRNAs) are a class of small, noncoding RNA that post-transcriptionally regulate protein expression. miRNAs are emerging as clinical biomarkers of many diseases, including tumors. The aim of this study was to investigate whether miRNA expression could vary in melanoma samples derived from formalin-fixed, paraffin-embedded (FFPE) tissues. The study included 4 groups: (1) 9 samples of oral canine malignant melanoma, (2) 10 samples of cutaneous malignant melanoma, (3) 5 samples of healthy oral mucosa, and (4) 7 samples of healthy skin. The expression levels of 6 miRNAs-miR-145, miR-146a, miR-425-5p, miR-223, miR-365, and miR-134-were detected and assessed by quantitative reverse transcription polymerase chain reaction (RT-qPCR) using TaqMan probes. Cutaneous canine malignant melanoma showed a decrease of the expression level of miR-145 and miR-365 and an increase of miR-146a and miR-425-5p compared to control samples. MiR-145 was also downregulated in oral canine malignant melanoma. The miRNAs with decreased expression may regulate genes involved in RAS, Rap1, and transforming growth factor β (TGF-β) signaling pathways, as well as upregulated genes associated with phosphatidylinositol signaling system, adherens junction, and RAS signaling pathways. In conclusion, miR-145, miR-365, miR-146a, and miR-425-5p were differentially expressed in canine malignant melanoma and healthy FFPE samples, suggesting that they may play a role in canine malignant melanoma pathogenesis.

Expression and predictive value of miR-489 and miR-21 in melanoma metastasis

BACKGROUND

Melanoma is a highly malignant skin tumour, and is one of the most rapidly growing malignant tumors in recent years. According to statistics, the morbidity of cancer increases with age, accounting for 1.6% of new cancer cases and 0.6% of deaths worldwide. Melanoma has a serious impact on society and families, thus it is of great significance to find biological markers related to the diagnosis and treatment of melanoma.

AIM

To explore the expression and predictive value of mir-489 and mir-21 in melanoma metastasis.

METHODS

A total of 60 patients with malignant melanoma treated at our hospital from June 2017 to December 2018 were selected as a research group, while 40 healthy subjects were selected as a control group. qRT-PCR technique was used to detect miR-489 and miR-21 in serum of the two groups. ROC curve was drawn to evaluate the predictive value and diagnostic efficiency. Spearman test was used for correlation analysis. Logistic single- and multiple-factor analyses were performed to identify the risk factors related to melanoma metastasis.

RESULTS

The expression of miR-489 in the research group was significantly lower than that in the control group (P < 0.001). However, the expression of miR-21 in the research group was significantly higher than that in the control group (P < 0.001). The expression of miR-489 and miR-21 was related to TNM stage and metastasis (P < 0.001). In the diagnosis of melanoma patients, the sensitivity, specificity, and AUC of miR-489 alone were 75.56%, 80.00%, and 0.852, respectively. The sensitivity, specificity, and AUC of miR-21 alone were 77.78%, 82.22%, and 0.844, respectively. MiR-489 was negatively correlated with TNM stage of melanoma (r = -0.612, P < 0.001), while miR-21 was positively correlated with TNM stage (r = 0.609, P < 0.001). Logistic single- and multiple-factor regression analyses showed that TNM stage, miR-489, and mir-21 were independent risk factors for malignant melanoma metastasis.

CONCLUSION

MiR-489 and miR-21 may participate in the process of melanoma occurrence, development, and metastasis, and can be used as potential serum biomarkers for melanoma metastasis diagnosis and disease assessment.

miR-145-5p inhibits tumor occurrence and metastasis through the NF-κB signaling pathway by targeting TLR4 in malignant melanoma

Compelling evidence shows that deregulated microRNAs (miRNAs) are important regulators in the progression of melanoma. miR-145-5p has been suggested to exhibit antitumorigenic activity in melanoma. However, the molecular mechanism underlying the biological activity of miR-145-5p in melanoma remains to be further understood. Herein, quantitative real-time polymerase chain reaction was used to examine the miR-145-5p expression in malignant melanoma tissues and cells. The interaction between miR-145-5p and toll-like receptor 4 (TLR4) was explored by bioinformatics analyses, luciferase reporter assay, and Western blot. The effects of miR-145-5p or combined with TLR4 on cell proliferation, colony formation, migration, and invasion abilities were investigated by (4,5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide, colony formation, wound healing, and transwell assays, respectively. The melanoma xenograft tumor models were established to determine the biological activity of miR-145-5p in melanoma in vivo. In addition, the changes of the nuclear factor kappa B (NF-κB) pathway were analyzed by detecting the NF-κB activity and the NF-κB p65 protein level. We observed that the miR-145-5p expression was underexpressed in melanoma tissues and cells. miR-145-5p suppressed the TLR4 expression by binding to its 3'untranslated region in melanoma cells. Moreover, TLR4 overexpression abolished the inhibition of cell proliferation, colony formation, migration, and invasion abilities induced by miR-145-5p in melanoma cells. Meanwhile, miR-145-5p was confirmed to restrain melanoma tumor growth in vivo by targeting TLR4. Furthermore, miR-145-5p overexpression inactivated the NF-κB pathway in melanoma in vitro and in vivo, which was reversed by TLR4 overexpression. We concluded that miR-145-5p hindered the occurrence and metastasis of melanoma cells in vitro and in vivo by targeting TLR4 via inactivation of the NF-κB pathway.

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.

MicroRNA heterogeneity in melanoma progression

The altered expression of miRNAs has been linked with neocarcinogenesis or the development of human malignancies including melanoma. Of significance, multiple clinical studies have documented that distinct sets of microRNAs (miRNAs) could be utilized as prognostic biomarkers for cancer development or predict the outcomes of treatment responses. To that end, an in-depth validation of such differentially expressed miRNAs is necessary in diverse settings of cancer patients in order to devise novel approaches to control tumor growth and/or enhance the efficacy of clinically-relevant therapeutic options. Moreover, considering the heterogeneity and sophisticated regulation of miRNAs, the precise delineation of their cellular targets could also be explored to design personalized medicine. Given the significance of miRNAs in regulating several key cellular processes of tumor cells including cell cycle progression and apoptosis, we review the findings of such miRNAs implicated in melanoma tumorigenesis. Understanding the novel mechanistic insights of such miRNAs will be useful for developing diagnostic or prognostic biomarkers or devising future therapeutic intervention for malignant melanoma.

Overexpression of long non-coding RNA NORAD promotes invasion and migration in malignant melanoma via regulating the MIR-205-EGLN2 pathway

Growing evidence suggests that long non-coding RNAs NORAD and miR-205 play a significant role in regulating cancer progression and metastasis. In this study, high expression of NORAD was firstly observed in melanoma tissues and human malignant melanoma cell lines, our aim was to study the interaction of them in the process of invasion and migration of malignant melanoma cells. NORAD, miR-205, and EGLN2 mRNA level in MM cells was detected by qRT-PCR. In situ hybridization (ISH) was performed to detect NORAD expression in MM tissues specimens. Effects of NORAD and miR-205 on Prolyl hydroxylase 2 (EGLN2) expression was explored by western blot in MM cells line. Dual-luciferase reporter assay was performed to verify the interaction relationship between NORAD and miR-205, as well as, miR-205 and EGLN2. Transwell assay was conducted to explore the effects of NORAD and miR-205 in vitro. Xenografts in nude mice experiment were used to confirm the role of NORAD and miR-205 in vivo. In vitro, NORAD knockdown significantly inhibited migration and invasion of malignant melanoma cells and elevated the expression of miR-205, there was an interaction between miR-205 and NORAD in the RNA-induced silencing complex. Upregulation of miR-205 induced significant inhibition of migratory and invasive ability compared with the scrambled control. However, downregulating NORAD largely reversed this effect. Furthermore, the regulatory effects of miR-205 on EGLN2 levels and the induction of endoplasmic reticulum stress were reversed by NORAD. In vivo, deletion of miR-205 induced tumor growth in nude mice. NORAD may play critical roles in tumorigenesis and progression of malignant melanoma by regulating of the miR-205-EGLN2 pathway, and may serve as a new therapeutic target.

Downregulation of intratumoral expression of miR-205, miR-200c and miR-125b in primary human cutaneous melanomas predicts shorter survival

While only 15–25 percent of melanoma patients develop distant metastasis and die, this disease is still responsible for the majority of skin cancer-related deaths. The availability of adjuvant therapies makes the selection of high-risk patients essential. We evaluated the intratumoral expression of ten miRNAs in primary melanomas in relation to its ability to predict melanoma survival. To this end, we correlated miRNA expression in 132 cryopreserved primary and metastatic tumors with clinicopathological factors and clinical outcome. We found sequential downregulation of intratumoral expression of miR-125b, miR-182, miR-200c and miR-205 over the full spectrum of melanoma progression. Moreover, downregulation of these miRNAs occurred in primary melanomas that further disseminated to distant sites. Furthermore, miR-125b, miR-200c and miR-205 correlated as independent factors with shorter survival. Our in vitro findings demonstrate that loss of miR-205 potentiates the invasive ability of melanoma cells. We conclude that the downregulation of miR-205 in primary melanomas is an intrinsic property that might contribute to distant metastasis. In particular, the interaction of melanoma cells with the extracellular matrix is one of the key mechanisms by which miR-205 influences melanoma metastasis. In conclusion, miR-125b, miR-200c and miR-205 are useful prognostic biomarkers at the time of diagnosis to select high-risk patients.

Identification of dysregulated microRNAs in canine malignant melanoma

Inhibiting aberrantly upregulated microRNAs (miR/miRNAs) has emerged as a novel focus for therapeutic intervention in human melanoma. Thus, identifying upregulated miRNAs is essential for identifying additional melanoma-associated therapeutic targets. In the present study, microarray-based miRNA profiling of canine malignant melanoma (CMM) tissue obtained from the oral cavity was performed and differential expression was confirmed by a reverse transcription-quantitative polymerase chain reaction (RT-qPCR). An analysis of the microarray data revealed 17 dysregulated miRNAs; 5 were upregulated and 12 were downregulated. RT-qPCR analysis was performed for 2 upregulated (miR-204 and miR-383), 3 downregulated (miR-122, miR-143 and miR-205) and 6 additional oncogenic miRNAs (oncomiRs; miR-16, miR-21, miR-29b, miR-92a, miR-125b and miR-222). The expression levels of seven of the miRNAs, miR-16, miR-21, miR-29b, miR-122, miR-125b, miR-204 and miR-383 were significantly upregulated; however, the expression of miR-205 was downregulated in CMM tissues compared with normal oral tissues. The microarray and RT-qPCR analyses validated the upregulation of two potential oncomiRs miR-204 and miR-383. The present study additionally constructed a protein interaction network and a miRNA-target regulatory interaction network using STRING and Cytoscape. In the proposed network, cyclin dependent kinase 2 was a target for miR-383, sirtuin 1 and tumor protein p53 were targets for miR-204 and ATR serine/threonine kinase was a target for both. It was concluded that miR-383 and miR-204 were potential oncomiRs that may be involved in regulating melanoma development by evading DNA repair and apoptosis.

MicroRNA-183 inhibits A375 human melanoma cell migration and invasion by targeting Ezrin and MMP-9

To assess the influence of microRNA-183 (miR-183) on the migration and invasion of A375 human melanoma cells, an A375 cell line with stable miR-183 overexpression or knockdown was constructed using lentiviral transfection. The change of miR-183 expression in these cells and in non-transfected controls was verified using reverse transcription-quantitative polymerase chain reaction. The impact of miR-183 on experimental A375 cell migration and invasion was assessed using a scratch and Transwell assay. The expression of Ezrin and matrix metalloprotease-9 (MMP-9), which are two mediator proteins that serve roles in tumor cell migration and invasion, were analyzed in each cell group via western blotting. The results of the present study indicated that miR-183 overexpression significantly inhibits A375 cell migration and invasion, which may be facilitated by miR-183 knockdown. Furthermore, Ezrin and MMP-9 protein levels were negatively associated with miR-183 expression, indicating that miR-183 may function as a tumor suppressor by inhibiting the expression of these two proteins. Additionally, miR-183 downregulation may be associated with the progression of melanoma.

Cantharidin inhibits melanoma cell proliferation via the miR‑21‑mediated PTEN pathway

Cantharidin (CTD) is an active component isolated from the blister beetle that has been demonstrated to exert antitumor effects on multiple types of cancer. The current study aimed to investigate whether the potential inhibitory effects of CTD exist in human melanoma cells and to assess the underlying antitumor mechanisms of CTD. Using the Cell Counting Kit‑8 assay, it was demonstrated that CTD treatment reduced A375 cell proliferation significantly in a dose‑dependent manner. The colony formation assay demonstrated that CTD treatment could decrease the number of A375 cell colonies. Using subcutaneous xenograft tumor models, it was also demonstrated that CTD retarded solid tumor growth significantly. Furthermore, CTD treatment could induce A375 cell apoptosis, as detected by Annexin V‑fluorescein isothiocyanate/propidium iodide staining and western blot analysis. Notably, CTD treatment reduced microRNA (miR)‑21 expression and enhanced phosphatase and tensin homolog (PTEN) protein expression levels in A375 cells. Furthermore, overexpressing miR‑21 in A375 cells with the miR‑21 agomir blocked the antitumor effect of CTD both in vitro and in vivo. Finally, it was demonstrated that the inhibitory effects of CTD on A375 cells may be regulated by attenuating miR‑21‑mediated PTEN suppression. Based on these observations, it was suggested that CTD be used as a novel anti‑proliferation agent of human melanoma via targeting the miR‑21‑PTEN signaling pathway.

Alterations in patient plasma microRNA expression profiles following resection of metastatic melanoma

BACKGROUND AND OBJECTIVES

MicroRNAs (miRs) are noncoding RNAs that regulate protein translation and melanoma progression. Changes in plasma miR expression following surgical resection of metastatic melanoma are under-investigated. We hypothesize differences in miR expression exist following complete surgical resection of metastatic melanoma.

METHODS

Blood collection pre- and post-surgical resection was performed in six individuals with solitary melanoma metastases. miR expression in extracted RNA was quantified using the NanoString nCounter Digital Analyzer.

RESULTS

Pre- and post-surgical plasma samples contained 216 miRs with expression above baseline. Comparison of postsurgical to preresection samples revealed differential expression of 25 miRs: miR-let-7a, miR-let7g, miR-15a, miR-16, miR-22, miR-30b, miR-126, miR-140, miR-145, miR-148a, miR-150-5p, miR-191, miR-378i, miR-449c, miR-494, miR-513b, miR-548aa, miR-571, miR-587, miR-891b, miR-1260a, miR 1268a, miR-1976, miR-4268, miR-4454 (P < 0.05). Utilizing P < 0.0046 as a cutoff to control for one false positive among the 216 miRs revealed that postsurgical melanoma plasma samples had upregulation of miR-1260a (P = 0.0007) and downregulation of miR-150-5p (P = 0.0026) relative to pre-surgical samples.

CONCLUSIONS

Differential expression of miR-150-5p and miR-1260a is present in plasma following surgical resection of metastatic melanoma in this small sample (n = 6) of melanoma patients. Therefore, further investigation of these plasma miRs as noninvasive biomarkers for melanoma is warranted.

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.

Quantification of microRNA-21 and microRNA-125b in melanoma tissue

Although microRNAs (miRNAs) have emerged as potent mediators of melanoma development and progression, a precise understanding of their oncogenic role remains unclear. In this study, we analysed formalin-fixed and paraffin-embedded tissues from two separate melanoma cohorts and from a series of benign melanocytic nevi. Using three different quantification methods [array analysis, quantitative PCR (qPCR) and in-situ hybridization (ISH) quantified by digital image analysis], we found considerable miRNA dysregulation in tumours. Using array analysis, samples mainly clustered according to their biological group (benign vs. malignant) and 77 miRNAs differed significantly between nevi and melanoma samples. Increase of miR-21 and miR-142, and decrease of miR-125b, miR-211, miR-101 and miR-513c in the melanomas were verified in both cohorts using qPCR, whereas the decrease of miR-205 observed with array analysis could not be confirmed using qPCR. ISH with digital quantification showed expression of miR-21 and miR-125b in the melanocytic lesions. miR-21 ISH was increased in melanomas, whereas quantification of miR-125b showed uniform ISH expression across nevi and melanomas. Our results support the important involvement of different miRNAs in melanoma biology and may serve as solid basics for further miRNA investigations in melanoma formalin-fixed and paraffin-embedded tissue. In particular, there is increased expression of miR-21 in melanomas compared with benign nevi.

MicroRNA-150 inhibitors enhance cell apoptosis of melanoma by targeting PDCD4

Malignant melanoma is a tumor with a high mortality rate. Previous studies have demonstrated that the oncogenesis of melanoma is associated with microRNA (miR)-150. However, the role of miR-150 in melanoma and its regulatory mechanisms are still unclear. In the present study, melanoma cancer tissues and adjacent normal tissues were obtained from 20 melanoma patients. The expression level of miR-150 in melanoma tissue and cell lines was detected by reverse transcription-quantitative polymerase chain reaction. miR-150 inhibitors/negative control were transfected into melanoma A375 cells in order to investigate the effects of miR-150 on cell proliferation, apoptosis, cell cycle migration and invasion using a Cell Counting Kit-8, colony formation, Hoechst 33528, flow cytometry, and Transwell assays. The association between miR-150 and programmed cell death protein-4 (PDCD4) was detected by a dual luciferase reporter assay. The functional role of PDCD4 in miR-150-affected melanoma cells was confirmed by small interfering (si)RNA knockdown. Results demonstrated that miR-150 was significantly upregulated and mRNA and protein expressions of PDCD4 were decreased in melanoma cancer tissues as compared with adjacent normal tissues. The level of PDCD4 was inversely associated with the level of miR-150. Transfection of miR-150 inhibitors suppressed cell proliferation, migration, and invasion, while the apoptosis of cells was promoted and G2/M cell arrest was induced. MiR-150 inhibitors enhanced the expression of caspase-8 and p21. The PDCD4 was identified as a direct target gene of miR-150. The effects of miR-150 inhibitors on apoptosis and apoptosis-associated proteins, including caspase-8 and p21, of A375 cells, were reversed following transfection of siRNA-PDCD4. Therefore, miR-150 inhibitors enhance cell apoptosis via upregulation of PDCD4-mediated activation of caspase-8 and p21. These findings demonstrate the potential for a promising therapeutic strategy in the management of melanoma.

Atypical Melanocytic Proliferations: A Review of the Literature

BACKGROUND

Ambiguous histopathologic diagnoses represent a challenge for clinicians because of a lack of definitive diagnosis and related uncertainty about management.

OBJECTIVE

To review the literature on atypical melanocytic proliferations and detail synonymous terms, epidemiology, diagnostic work-up, histopathology, treatment, and prognosis.

METHODS

Databases from PubMed and Web of Science were searched for articles related to atypical melanocytic proliferations.

RESULTS

Intraepidermal melanocytic proliferations with features worrisome for possible melanoma in situ (MIS) are generally excised as for MIS. Reported rates of upstaging of such cases to invasive melanoma on review of the excision are very low. Because invasion, lymph node spread, and metastasis can occur in atypical melanocytic lesions with a thick intradermal component, these are often treated as for malignant melanoma.

CONCLUSION

Because the diagnosis dictates treatment, it is incumbent to establish a diagnosis as definitive as possible, obtaining second or third opinions and using ancillary studies when appropriate. When the diagnosis remains uncertain, it is difficult to provide guidelines for treatment. Clinical care decisions for patients with an uncertain diagnosis are best done on a case-by-case basis weighing probabilities of adverse outcomes against potential benefits and risks from various treatment options.

Recent advances in melanoma research via "omics" platforms

Melanoma has a high mortality rate and metastatic melanoma is highly resistant to conventional therapies. "Omics" fields such as proteomics and microRNA and exosome studies have provided new knowledge to complement the information generated by genomic studies. This work aimed to review the current status of biomarker discovery for melanoma through multi-"omics" platforms. A few sets of novel microRNAs and proteins are described, some of them with important implications in suppressing melanoma at different stages. Upregulation of genes involved in angiogenesis, immunosuppressive factors, modification of stroma, capture of melanoma cells in lymph nodes and factors responsible for tumour cell recruitment have been identified in exosomes, among molecules with other functions. A remarkable series of proteins involved in epithelial-mesenchymal/mesenchymal-epithelial transitions, inflammation, motility, proliferation and progression processes, centrosome amplification, aneuploidy, inhibition of CD8+ effector T-cells, and metastasis in general were identified. Genomic and protein-protein interactions or metabolome levels were not analysed. Proteomics tools such as Orbitrap shotgun mass spectrometry or deep mining proteomic analysis utilizing high-resolution reversed phase nanoseparation in combination with mass spectrometry are also discussed. The application of these tools together with bioinformatics approaches applied to the clinical setting will enable the implementation of personalized medicine in the near future.

Epigenetics of malignant melanoma

Patients with malignant melanoma generally have a good prognosis if the disease presents prior to metastasis. Due to progress with targeted and immunotherapies, the median survival of metastatic melanoma patients is now over 2 years. The disease is characterised by one of the highest somatic mutation rates observed amongst cancer types, with a specific mutational signature based on UV radiation damage evident. Highly prevalent mutations, such as the BRAF^V600E, in the MAPK cascade indicate truncal involvement of this pathway in the earliest stage of melanoma. The molecular sub-classification of melanoma based on genetic alterations is now well established. This has paved the way for researchers in epigenetics to investigate specific pathways of known importance, and the involvement of the diverse range of epigenetic mechanisms. Herein, we review the literature to highlight that epigenetic alterations are integrally involved in this malignancy. We focus on the most current evidence around the epigenetic mechanisms: DNA methylation and demethylation including 5-hydroxy-methylcytosine; histone post-translational modifications including variant histones; chromatin remodelling complexes and in particular the polycomb-repressive complex PRC2 and its histone methyltransferase subunit EZH2; and non-coding RNAs. Each mechanism is described generally, studies involving melanoma are assessed and clinical relevance is highlighted where possible.

FAK regulates E-cadherin expression via p-SrcY416/p-ERK1/2/p-Stat3Y705 and PPARγ/miR-125b/Stat3 signaling pathway in B16F10 melanoma cells

Focal adhesion kinase (FAK) is involved in tumor cell migration and metastasis. However, the underlying mechanism remains unclear. Here, we present a signaling pathway involved in the regulation of melanoma cell migration by FAK. We found that the interference of FAK expression suppressed B16F10 cell migration/metastasis, and altered the expressions of genes involved in melanoma migration/metastasis. The down-regulation of FAK inhibited the expression of p-Src^Y416, p-ERK_1/2, Stat3 and p-Stat3^Y705, while promoted the expression of PPARγ, miR-125b and E-cadherin. Then we found that FAK inhibited E-cadherin expression via p-Src^Y416/p-ERK_1/2/ p-Stat3^Y705 and PPARγ/miR-125b/Stat3 signaling pathway in B16F10 cell. Moreover, miR-125b inhibited B16F10 cell migration. Furthermore, we repeated the key data with human melanoma cell line A375. The results obtained from A375 cells fell in line with those from B16F10 cells. Using Oncomine database, we found that the mRNA levels of FAK, Src, ERK_1/2 and Stat3 increased, while the mRNA levels of PPARγ, C21orf34 (miR-125b host gene) and E-cadherin decreased in human metastatic melanoma. The data from human breast cancer confirmed those from metastatic melanoma.

Taken together, our study suggests that down-regulation of FAK promotes E-cadherin expression via p-Src^Y416/p-ERK_1/2/p-Stat3^Y705 and PPARγ/miR-125b/Stat3 signaling pathway. Our findings provide a novel explanation regarding how FAK promotes melanoma cell migration, suggesting that FAK might be a potential target for melanoma therapy.

MicroRNA profiling associated with non-small cell lung cancer: next generation sequencing detection, experimental validation, and prognostic value

Background

The average five-year survival for non-small cell lung cancer (NSCLC) patients is approximately 15%. Emerging evidence indicates that microRNAs (miRNAs) constitute a new class of gene regulators in humans that may play an important role in tumorigenesis. Hence, there is growing interest in studying their role as possible new biomarkers whose expression is aberrant in cancer. Therefore, in this study we identified dysregulated miRNAs by next generation sequencing (NGS) and analyzed their prognostic value.

Methods

Sequencing by oligo ligation detection technology was used to identify dysregulated miRNAs in a training cohort comprising paired tumor/normal tissue samples (N = 32). We validated 22 randomly selected differentially-expressed miRNAs by quantitative real time PCR in tumor and adjacent normal tissue samples (N = 178). Kaplan-Meier survival analysis and Cox regression were used in multivariate analysis to identify independent prognostic biomarkers.

Results

NGS analysis revealed that 39 miRNAs were dysregulated in NSCLC: 28 were upregulated and 11 were downregulated. Twenty-two miRNAs were validated in an independent cohort. Interestingly, the group of patients with high expression of both miRNAs (miR-21^high and miR-188^high) showed shorter relapse-free survival (RFS) and overall survival (OS) times. Multivariate analysis confirmed that this combined signature is an independent prognostic marker for RFS and OS (p = 0.001 and p < 0.0001, respectively).

Conclusions

NGS technology can specifically identify dysregulated miRNA profiles in resectable NSCLC samples. MiR-21 or miR-188 overexpression correlated with a negative prognosis, and their combined signature may represent a new independent prognostic biomarker for RFS and OS.

Curcumin and treatment of melanoma: The potential role of microRNAs

Melanoma is the most aggressive type of skin cancer and is characterized by poor prognosis in its advanced stages because treatments are poorly effective and burdened with severe adverse effects. MicroRNAs (miRNAs) are small non-coding RNAs that are implicated in several cellular processes; they are categorized as oncogenic and tumor suppressor miRNAs. Several miRNAs are implicated in the pathogenesis and progression of melanoma, such as the tumor suppressor miR-let7b that targets cyclin D and regulates cell cycle. Curcumin is a natural compound derived from Curcuma longa L. (turmeric) with anti-cancer properties, documented also in melanoma, and is well tolerated in humans. Pharmacological activity of curcumin is mediated by modulation of several pathways, such as JAK-2/STAT3, thus inhibiting melanoma cell migration and invasion and enhancing apoptosis of these cells. The low oral bioavailability of curcumin has led to the development of curcumin analogues, such as EF24, with greater anti-tumor efficacy and metabolic stability. Potential anti-cancer activity of curcumin and its analogues is also mediated by modulation of miRNAs such as miR21, that is implicated in cell cycle regulation and apoptosis through down-regulation of PTEN and PDCD4 proteins. Curcumin has a potential role in the treatment of melanoma, though further studies are necessary to explore its clinical efficacy.

Plasma MicroRNA Levels Following Resection of Metastatic Melanoma

Melanoma remains the leading cause of skin cancer–related deaths. Surgical resection and adjuvant therapies can result in disease-free intervals for stage III and stage IV disease; however, recurrence is common. Understanding microRNA (miR) dynamics following surgical resection of melanomas is critical to accurately interpret miR changes suggestive of melanoma recurrence. Plasma of 6 patients with stage III (n = 2) and stage IV (n = 4) melanoma was evaluated using the NanoString platform to determine pre- and postsurgical miR expression profiles, enabling analysis of more than 800 miRs simultaneously in 12 samples. Principal component analysis detected underlying patterns of miR expression between pre- vs postsurgical patients. Group A contained 3 of 4 patients with stage IV disease (pre- and postsurgical samples) and 2 patients with stage III disease (postsurgical samples only). The corresponding preoperative samples to both individuals with stage III disease were contained in group B along with 1 individual with stage IV disease (pre- and postsurgical samples). Group A was distinguished from group B by statistically significant analysis of variance changes in miR expression (P < .0001). This analysis revealed that group A vs group B had downregulation of let-7b-5p, miR-520f, miR-720, miR-4454, miR-21-5p, miR-22-3p, miR-151a-3p, miR-378e, and miR-1283 and upregulation of miR-126-3p, miR-223-3p, miR-451a, let-7a-5p, let-7g-5p, miR-15b-5p, miR-16-5p, miR-20a-5p, miR-20b-5p, miR-23a-3p, miR-26a-5p, miR-106a-5p, miR-17-5p, miR-130a-3p, miR-142-3p, miR-150-5p, miR-191-5p, miR-199a-3p, miR-199b-3p, and miR-1976. Changes in miR expression were not readily evident in individuals with distant metastatic disease (stage IV) as these individuals may have prolonged inflammatory responses. Thus, inflammatory-driven miRs coinciding with tumor-derived miRs can blunt anticipated changes in expression profiles following surgical resection.

Increased microRNA 21 expression contributes to arsenic induced skin lesions, skin cancers and respiratory distress in chronically exposed individuals

More than 26 million people in West Bengal, India, are exposed to arsenic through drinking water, leading to several deleterious endpoints including precancerous and cancerous skin lesions and other non-dermatological health effects. Here, our aim was to identify whether miR21 is associated with such dermatological and non-dermatological health outcomes in chronically exposed humans. A total of 123 subjects from West Bengal were recruited for this study (45 exposed individuals with skin lesions, 38 exposed individuals without skin lesions and 40 unexposed individuals). The miR21 expression patterns in the lymphocytes were studied by quantitative realtime PCR and the effects on downstream targets were validated by Western blotting. Associations between the miR21 expression patterns and non-dermatological health effects were determined from epidemiological survey data. In vitro studies were done with low dose (0.05ppm) of chronic arsenic exposure to HaCaT cells for 15 passages. Interestingly, within the exposed group, the skin lesion individuals showed almost 4.5 fold up-regulation of miR21 compared to the no skin lesion group. The expression of the downstream targets of miR21 (PTEN and PDCD4) varied inversely, while the expression of pAKT and PI3K varied proportionately with its expression levels. Results of in vitro studies showed similar trends. Again miR21 was 2.03 fold up-regulated in the exposed individuals with respiratory diseases compared to the individuals without the same. This study for the first time shows that miR21 plays an important role in contributing to arsenic induced dermatological and non-dermatological health outcomes in an exposed population.