Association of miR-146a-5p and miR-21-5p with Prognostic Features in Melanomas

BACKGROUND

Cutaneous melanoma (CM) is one of the most lethal tumors among skin cancers and its incidence is rising worldwide. Recent data support the role of microRNAs (miRNAs) in melanoma carcinogenesis and their potential use as disease biomarkers.

METHODS

We quantified the expression of miR-146a-5p and miR-21-5p in 170 formalin-fixed paraffin embedded (FFPE) samples of CM, namely 116 superficial spreading melanoma (SSM), 26 nodular melanoma (NM), and 28 lentigo maligna melanoma (LMM). We correlated miRNA expression with specific histopathologic features including Breslow thickness (BT), histological subtype, ulceration and regression status, and mitotic index.

RESULTS

miR-146a-5p and miR-21-5p were significantly higher in NM compared to SSM and LMM. The positive correlation between miR-146a-5p and miR-21-5p expression and BT was confirmed for both miRNAs in SSM. Considering the ulceration status, we assessed that individual miR-21-5p expression was significantly higher in ulcerated CMs. The increased combined expression of the two miRNAs was strongly associated with ulceration (p = 0.0093) and higher mitotic rate (≥1/mm2) (p = 0.0005). We demonstrated that the combination of two-miRNA expression and prognostic features (BT and ulceration) can better differentiate cutaneous melanoma prognostic groups, considering overall survival and time-to-relapse clinical outcomes. Specifically, miRNA expression can further stratify prognostic groups among patients with BT ≥ 0.8 mm but without ulceration. Our findings provide further insights into the characterization of CM with specific prognostic features. The graphical abstract was created with BioRender.com.

Blood-based microRNAs as Potential Diagnostic Biomarkers for Melanoma: A Meta-Analysis

INTRODUCTION

Circulating microRNAs (miRNAs) serve as noninvasive diagnostic markers in many cancers. This meta-analysis aims to evaluate the diagnostic efficacy of circulating microRNAs for melanoma.

MATERIALS AND METHODS

The pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio, and ROC curve were evaluated using the Meta-Disc V.1.4 and Comprehensive Meta-Analysis V.3.3 software packages. To investigate the heterogeneity, the I2 and Chi-square tests were used. The publishing bias was evaluated using Begg's rank correlation and Egger regression asymmetry tests.

RESULTS

A total of 9 articles covering 13 studies (more than 50 miRs individually and in combination) were included, containing 1,355 participants (878 cases and 477 controls). The overall pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio (DOR), and AUC were 0.78 (95% CI: 0.76-0.81), 0.80 (95% CI: 0.77-0.83), 4.32 (95% CI: 3.21-5.82), 0.17 (95% CI: 0.09-0.32), 28.0 (95% CI: 15.34-51.09), and 0.91, respectively. According to Begg's and Egger's tests, there was no publication bias (Begg's p = 0.160 and Egger's p = 0.289).

CONCLUSION

Circulating miRNAs can serve as fair and non-invasive diagnostic biomarkers for melanoma. Additionally, specific miRNAs still need to be discovered for diagnosing melanoma.

A novel Telomerase activity and microRNA-21 upregulation identified in a family with Palmoplantar keratoderma

Palmoplantar keratoderma is a set of skin diseases with hyperkeratotic thickening of palms and soles which are characteristic of these heterogeneous group of keratinization disorders. Various genetic mutations, autosomal dominant or recessive, have been identified which may triggerpalmoplantar keratoderma, as KRT9 (Keratin 9), KRT1 (Keratin1), AQP5 (Aquaporin), SERPINB 7 (serine protease inhibitor). The identification of causal mutations is extremely important for the correct diagnosis. Here, we report the case of a family affected from Palmoplantar keratoderma caused by autosomal dominant KRT1 mutations (Unna-Thost disease). Telomerase activation and hTERT expression take a part in the process of cell proliferation and inflammation and microRNAs, as microRNA-21, are emerging as drivers in the regulation of telomerase activity. Here, the patients underwent KRT1 analysis genetic sequence, telomerase activity and miR-21 expression. Beside histopathology assay was performed. The patients presented thickening of the skin on soles of the feet and the palms of the hands, KRT1mutations and showed high expression levels of hTERT and hTR, the gene encoding for the telomeric subunits, and miR-21 (fold change >1.5 and p value =0.043), explicating the aberrant proliferation of epidermal layer and the inflammatory state characterizing palmoplantar keratoderma.

Potential Pathogenic Impact of Cow’s Milk Consumption and Bovine Milk-Derived Exosomal MicroRNAs in Diffuse Large B-Cell Lymphoma

Epidemiological evidence supports an association between cow’s milk consumption and the risk of diffuse large B-cell lymphoma (DLBCL), the most common non-Hodgkin lymphoma worldwide. This narrative review intends to elucidate the potential impact of milk-related agents, predominantly milk-derived exosomes (MDEs) and their microRNAs (miRs) in lymphomagenesis. Upregulation of PI3K-AKT-mTORC1 signaling is a common feature of DLBCL. Increased expression of B cell lymphoma 6 (BCL6) and suppression of B lymphocyte-induced maturation protein 1 (BLIMP1)/PR domain-containing protein 1 (PRDM1) are crucial pathological deviations in DLBCL. Translational evidence indicates that during the breastfeeding period, human MDE miRs support B cell proliferation via epigenetic upregulation of BCL6 (via miR-148a-3p-mediated suppression of DNA methyltransferase 1 (DNMT1) and miR-155-5p/miR-29b-5p-mediated suppression of activation-induced cytidine deaminase (AICDA) and suppression of BLIMP1 (via MDE let-7-5p/miR-125b-5p-targeting of PRDM1). After weaning with the physiological termination of MDE miR signaling, the infant’s BCL6 expression and B cell proliferation declines, whereas BLIMP1-mediated B cell maturation for adequate own antibody production rises. Because human and bovine MDE miRs share identical nucleotide sequences, the consumption of pasteurized cow’s milk in adults with the continued transfer of bioactive bovine MDE miRs may de-differentiate B cells back to the neonatal “proliferation-dominated” B cell phenotype maintaining an increased BLC6/BLIMP1 ratio. Persistent milk-induced epigenetic dysregulation of BCL6 and BLIMP1 expression may thus represent a novel driving mechanism in B cell lymphomagenesis. Bovine MDEs and their miR cargo have to be considered potential pathogens that should be removed from the human food chain.

Oxidative-Stress-Sensitive microRNAs in UV-Promoted Development of Melanoma

Melanoma is the most aggressive and life-threatening form of skin cancer. Key molecular events underlying the melanocytic transformation into malignant melanoma mainly involve gene mutations in which exposure to ultraviolet (UV) radiation plays a prominent role. However, several aspects of UV-induced melanomagenesis remain to be explored. Interestingly, redox-mediated signaling and perturbed microRNA (miRNA) profiles appear to be interconnected contributing factors able to act synergistically in melanoma initiation and progression. Since UV radiation can promote both redox imbalance and miRNA dysregulation, a harmful crosstalk between these two key cellular networks, with UV as central hub among them, is likely to occur in skin tissue. Therefore, decoding the complex circuits that orchestrate the interaction of UV exposure, oxidative stress, and dysregulated miRNA profiling can provide a deep understanding of the molecular basis of the melanomagenesis process. Furthermore, these mechanistic insights into the reciprocal regulation between these systems could have relevant implications for future therapeutic approaches aimed at counteracting UV-induced redox and miRNome imbalances for the prevention and treatment of malignant melanoma. In this review, we illustrate current information on the intricate connection between UV-induced dysregulation of redox-sensitive miRNAs and well-known signaling pathways involved in the malignant transformation of normal melanocytes to malignant melanoma.

Nanoparticle delivery of miR-21-3p sensitizes melanoma to anti-PD-1 immunotherapy by promoting ferroptosis

Background

Although anti-programmed cell death protein 1 (PD-1) immunotherapy is greatly effective in melanoma treatment, low response rate and treatment resistance significantly hinder its efficacy. Tumor cell ferroptosis triggered by interferon (IFN)-γ that is derived from tumor-infiltrating CD8⁺ T cells greatly contributes to the effect of immunotherapy. However, the molecular mechanism underlying IFN-γ-mediated ferroptosis and related potentially promising therapeutic strategy warrant further clarification. MicroRNAs (miRNAs) participate in ferroptosis execution and can be delivered systemically by multiple carriers, which have manifested obvious therapeutic effects on cancer.

Methods

MiRNAs expression profile in IFN-γ-driven ferroptosis was obtained by RNA sequencing. Biochemical assays were used to clarify the role of miR-21-3p in IFN-γ-driven ferroptosis and the underlying mechanism. MiR-21-3p-loaded gold nanoparticles were constructed and systemically applied to analyze the role of miR-21-3p in anti-PD-1 immunotherapy in preclinical transplanted tumor model.

Results

MiRNAs expression profile of melanoma cells in IFN-γ-driven ferroptosis was first obtained. Then, upregulated miR-21-3p was proved to facilitate IFN-γ-mediated ferroptosis by potentiating lipid peroxidation. miR-21-3p increased the ferroptosis sensitivity by directly targeting thioredoxin reductase 1 (TXNRD1) to enhance lipid reactive oxygen species (ROS) generation. Furthermore, miR-21-3p overexpression in tumor synergized with anti-PD-1 antibody by promoting tumor cell ferroptosis. More importantly, miR-21-3p-loaded gold nanoparticles were constructed, and the systemic delivery of them increased the efficacy of anti-PD-1 antibody without prominent side effects in preclinical mice model. Ultimately, ATF3 was found to promote miR-21-3p transcription in IFN-γ-driven ferroptosis.

Conclusions

MiR-21–3 p upregulation contributes to IFN-γ-driven ferroptosis and synergizes with anti-PD-1 antibody. Nanoparticle delivery of miR-21–3 p is a promising therapeutic approach to increase immunotherapy efficacy without obvious systemic side effects.

Nobiletin-loaded composite penetration enhancer vesicles restore the normal miRNA expression and the chief defence antioxidant levels in skin cancer

Skin cancer is one of the most dangerous diseases, leading to massive losses and high death rates worldwide. Topical delivery of nutraceuticals is considered a suitable approach for efficient and safe treatment of skin cancer. Nobiletin; a flavone occurring in citrus fruits has been reported to inhibit proliferation of carcinogenesis since 1990s, is a promising candidate in this regard. Nobiletin was loaded in various vesicular systems to improve its cytotoxicity against skin cancer. Vesicles were prepared using the thin film hydration method, and characterized for particle size, zeta potential, entrapment efficiency, TEM, ex-vivo skin deposition and physical stability. Nobiletin-loaded composite penetration enhancer vesicles (PEVs) and composite transfersomes exhibited particle size 126.70 ± 11.80 nm, 110.10 ± 0.90 nm, zeta potential + 6.10 ± 0.40 mV, + 9.80 ± 2.60 mV, entrapment efficiency 93.50% ± 3.60, 95.60% ± 1.50 and total skin deposition 95.30% ± 3.40, 100.00% ± 2.80, respectively. These formulations were selected for cytotoxicity study on epidermoid carcinoma cell line (A431). Nobiletin-loaded composite PEVs displayed the lowest IC50 value, thus was selected for the in vivo study, where it restored skin condition in DMBA induced skin carcinogenesis mice, as delineated by histological and immuno-histochemical analysis, biochemical assessment of skin oxidative stress biomarkers, in addition to miRNA21 and miRNA29A. The outcomes confirmed that nobiletin- loaded composite PEVs is an efficient delivery system combating skin cancer.

Epigenetic Regulation in Melanoma: Facts and Hopes

Cutaneous melanoma is a lethal disease, even when diagnosed in advanced stages. Although recent progress in biology and treatment has dramatically improved survival rates, new therapeutic approaches are still needed. Deregulation of epigenetics, which mainly controls DNA methylation status and chromatin remodeling, is implied not only in cancer initiation and progression, but also in resistance to antitumor drugs. Epigenetics in melanoma has been studied recently in both melanoma preclinical models and patient samples, highlighting its potential role in different phases of melanomagenesis, as well as in resistance to approved drugs such as immune checkpoint inhibitors and MAPK inhibitors. This review summarizes what is currently known about epigenetics in melanoma and dwells on the recognized and potential new targets for testing epigenetic drugs, alone or together with other agents, in advanced melanoma patients.

Ketogenic Diet in Cancer Prevention and Therapy: Molecular Targets and Therapeutic Opportunities

Although cancer is still one of the most significant global challenges facing public health, the world still lacks complementary approaches that would significantly enhance the efficacy of standard anticancer therapies. One of the essential strategies during cancer treatment is following a healthy diet program. The ketogenic diet (KD) has recently emerged as a metabolic therapy in cancer treatment, targeting cancer cell metabolism rather than a conventional dietary approach. The ketogenic diet (KD), a high-fat and very-low-carbohydrate with adequate amounts of protein, has shown antitumor effects by reducing energy supplies to cells. This low energy supply inhibits tumor growth, explaining the ketogenic diet's therapeutic mechanisms in cancer treatment. This review highlights the crucial mechanisms that explain the ketogenic diet's potential antitumor effects, which probably produces an unfavorable metabolic environment for cancer cells and can be used as a promising adjuvant in cancer therapy. Studies discussed in this review provide a solid background for researchers and physicians to design new combination therapies based on KD and conventional therapies.

MicroRNA Signature in Melanoma: Biomarkers and Therapeutic Targets

Melanoma is the utmost fatal kind of skin neoplasms. Molecular changes occurring during the pathogenic processes of initiation and progression of melanoma are diverse and include activating mutations in BRAF and NRAS genes, hyper-activation of PI3K/AKT pathway, inactivation of p53 and alterations in CDK4/CDKN2A axis. Moreover, several miRNAs have been identified to be implicated in the biology of melanoma through modulation of expression of genes being involved in these pathways. In the current review, we provide a summary of the bulk of information about the role of miRNAs in the pathobiology of melanoma, their possible application as biomarkers and their emerging role as therapeutic targets for this kind of skin cancer.

MicroRNA-21 Contributes to Cutaneous Squamous Cell Carcinoma Progression via Mediating TIMP3/PI3K/AKT Signaling Axis

BACKGROUND

Though the therapeutic potentials of microRNAs (miRNAs) are extensively explored in cutaneous squamous cell carcinoma (CSCC), the concrete function of miR-21 in this disorder has not been thoroughly comprehended. Therein, this work is launched to clarify the miR-21-pivoted mechanism in CSCC from the perspective of tissue inhibitor of metalloproteinases-3 (TIMP3) and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway.

METHODS

Microarray-based analysis was utilized to screen out miR-21 with the most up-regulated expression in CSCC tissues. The relation between miR-21 and TIMP3 expression in tissues, and the overall survival of CSCC patients was evaluated. Loss-of-function assays were performed in cells to explore the independent and combined functions of miR-21 and TIMP3 in CSCC cell progression. Mice were injected with miR-21 inhibitor or TIMP3 si for identifying their roles in tumor formation and liver metastasis. The mechanism among miR-21, TIMP3 and PI3K/AKT pathway was interpreted.

RESULTS

MiR-21 was up-regulated while TIMP3 was down-regulated in CSCC tissues, which were connected with unsatisfactory survival of patients. Down-regulating miR-21 inhibited CSCC cell progression and retarded CSCC tumor formation and metastasis in mice. Silencing of TIMP3 reversed the effects of miR-21 down-regulation on CSCC progression. Besides, down-regulating miR-21 inhibited PI3K/AKT pathway activation in CSCC cells via mediating TIMP3.

CONCLUSION

It is elucidated that miR-21 depletion impedes CSCC cell invasion and metastasis via enhancing TIMP3 and suppressing PI3K/AKT pathway activation.

The role of CAF derived exosomal microRNAs in the tumour microenvironment of melanoma

Exosomes play a crucial role in the crosstalk between cancer associated fibroblasts (CAFs) and cancer cells, contributing to carcinogenesis and the tumour microenvironment. Recent studies have revealed that CAFs, normal fibroblasts and cancer cells all secrete exosomes that contain miRNA, establishing a cell-cell communication network within the tumour microenvironment. For example, miRNA dysregulation in melanoma has been shown to promote CAF activation via induction of epithelial-mesenchymal transition (EMT), which in turn alters the secretory phenotype of CAFs in the stroma. This review assesses the roles of melanoma exosomal miRNAs in CAF formation and how CAF exosome-mediated feedback signalling to melanoma lead to tumour progression and metastasis. Moreover, efforts to exploit exosomal miRNA-mediated network communication between tumour cells and their microenvironment, and their potential as prognostic biomarkers or novel therapeutic targets in melanoma will also be considered.

Melanoma-Derived Exosomes Endow Fibroblasts with an Invasive Potential via miR-21 Target Signaling Pathway

Background

Tumor-derived exosomes are messengers that participate in tumor progression. Fibroblasts are associated with the metastasis of cancer depending on their cellular plasticity. We hypothesize that tumor-derived exosomes endow the fibroblasts in tumor microenvironment with invasive phenotype to the benefit of tumor metastasis.

Materials and Methods

Exosomes derived from B16-F10 cells were identified by nanoparticle tracking analyzer (NTA), dynamic light scattering (DLS), Western blot (WB), and transmission electron microscopy (TEM). Cell invasion and migration assays were performed using the xCELLigence real-time cell analyzer (RTCA). Role of tumor-derived exosomal miR-21 in cell invasion was determined by qPCR.

Results

The invasion analysis showed that exosome-treated fibroblast cells had greater invasive capability as compared to untreated fibroblast cells, with the higher expressions of MMP2 and MMP9. miR-21 is at least partially responsible for this effect. After ingestion of melanoma-derived exosomes during incubation, mouse embryonic fibroblasts cells emerged cellular invasiveness with the presentation of a marked increase in miR-21 expression. MiR-21 promoted invasion of fibroblasts by down-regulation of tissue inhibitor of metalloproteinase 3 (TIMP3) expression and increasing of matrix metalloprotein (MMP) expression in fibroblast cells via melanoma-derived exosomes in a time-dependent manner.

Conclusion

Our results suggest that tumor-derived exosomes may facilitate stromal fibroblasts an aggressive phenotype to equip the tumor progression.

Serum levels of miRNA-21-5p in vitiligo patients and effects of miRNA-21-5p on SOX5, beta-catenin, CDK2 and MITF protein expression in normal human melanocytes

BACKGROUND

Epigenetics of vitiligo was evaluated in few studies. In particular, the role of miR-21, a microRNA involved in various processes, including melanogenesis, was never investigated.

OBJECTIVE

Evaluation of serum levels of miR-21-5p in vitiligo patients and miR-21-5p effects on melanogenesis.

METHODS

We measured serum levels of miR-21-5p in 40 patients affected by nonsegmental vitiligo and 40 sex- and age-matched healthy controls. Next, normal human melanocytes were transfected with miR-21-5p to study the effects of this microRNA, which targeted some proteins involved in melanogenesis pathway like SOX5, beta-catenin, cyclin-dependent kinase 2 (CDK2), and MITF.

RESULTS

The expression of miR-21-5p in vitiligo patients was 3.6-4454.4 fold (mean 990.4 ± 1397.9) higher than in controls. The relative expression of miR-21-5p was directly and significantly correlated with disease severity, defined by VASI (Vitiligo Area and Severity Index) score (Rho = 0.89, p = 10^-7), but not other individual or clinical characteristics. In the second part of the study, a significant reduction of SOX5, beta-catenin and CDK2 protein expression and increase of MITF protein expression was observed in cultured melanocytes after 24 h trasfection with miR-21-5p.

CONCLUSION

According to literature, miR-21-5p upregulation and consequent SOX5 downregulation should upregulate melanogenesis, while vitiligo is characterized by skin depigmentation. Our results suggest that current knowledge of the pathogenesis of vitiligo is probably incomplete. Clinical manifestations could result from an altered balance between metabolic pathways with contrasting effects. In this view, miR-21-5p upregulation might be a tentative compensation mechanism. Further studies appear necessary to confirm and better understand our results and their importance.

Importance of microRNAs in Skin Oncogenesis and Their Suitability as Agents and Targets for Topical Therapy

Skin cancer is the most common cancer worldwide, with rapidly increasing incidence and consistent mortality. Skin cancer encompasses melanoma and non-melanoma skin cancer, which in turn is mainly divided into cutaneous squamous cell carcinoma and basal cell carcinoma. Small noncoding micro-RNAs (miRNAs) regulate protein expression after transcription and play a role in the development and progression of skin cancer. Deregulated expression of miRNAs in skin cancer is associated with cell proliferation, angiogenesis, metastasis, apoptosis, immune response, and drug resistance. Specific patterns of miRNAs in specific skin cancer types can be used as diagnostic markers. For therapeutic purposes, both miRNA and chemically modified variants thereof as well as miRNA antagonists (antagomiRs) or RNA inhibitors may be applied topically. Due to their specific physicochemical properties, physical or chemical diffusion promoters are used with varying degrees of success. There is no question by now that such preparations have a high potential for the treatment of epithelial skin tumors in particular.

MicroRNA-21-Enriched Exosomes as Epigenetic Regulators in Melanomagenesis and Melanoma Progression: The Impact of Western Lifestyle Factors

DNA mutation-induced activation of RAS-BRAF-MEK-ERK signaling associated with intermittent or chronic ultraviolet (UV) irradiation cannot exclusively explain the excessive increase of malignant melanoma (MM) incidence since the 1950s. Malignant conversion of a melanocyte to an MM cell and metastatic MM is associated with a steady increase in microRNA-21 (miR-21). At the epigenetic level, miR-21 inhibits key tumor suppressors of the RAS-BRAF signaling pathway enhancing proliferation and MM progression. Increased MM cell levels of miR-21 either result from endogenous upregulation of melanocytic miR-21 expression or by uptake of miR-21-enriched exogenous exosomes. Based on epidemiological data and translational evidence, this review provides deeper insights into environmentally and metabolically induced exosomal miR-21 trafficking beyond UV-irradiation in melanomagenesis and MM progression. Sources of miR-21-enriched exosomes include UV-irradiated keratinocytes, adipocyte-derived exosomes in obesity, airway epithelium-derived exosomes generated by smoking and pollution, diet-related exosomes and inflammation-induced exosomes, which may synergistically increase the exosomal miR-21 burden of the melanocyte, the transformed MM cell and its tumor environment. Several therapeutic agents that suppress MM cell growth and proliferation attenuate miR-21 expression. These include miR-21 antagonists, metformin, kinase inhibitors, beta-blockers, vitamin D, and plant-derived bioactive compounds, which may represent new options for the prevention and treatment of MM.

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.

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.

Transcriptomic Analysis of Coding Genes and Non-Coding RNAs Reveals Complex Regulatory Networks Underlying the Black Back and White Belly Coat Phenotype in Chinese Wuzhishan Pigs

Coat color is one of the most important characteristics for distinguishing Chinese indigenous pig breeds. In Wuzhishan pigs, the animals have black on the back and white on the abdomen. However, the molecular genetic basis of this phenotype is unclear. In this study, we used high-throughput RNA sequencing to compare expression profiles of coding and non-coding RNAs from white and black skin samples obtained from individual Wuzhishan pigs. The expression profiling revealed that 194 lncRNAs (long non-coding RNAs), 189 mRNAs (messenger RNAs), and 162 miRNAs (microRNAs) had significantly different levels of expression (|log₂ fold change| > 1, p-value < 0.05) in white and black skin. Compared to RNA levels in black skin, white skin had higher levels of expression of 185 lncRNAs, 181 mRNAs, and 23 miRNAs and lower levels of expression of 9 lncRNAs, 8 mRNAs, and 139 miRNAs. Functional analysis suggested that the differentially expressed transcripts are involved in biological processes such as melanin biosynthesis, pigmentation and tyrosine metabolism. Several key genes involved in melanogenesis, including MLANA, PMEL, TYR, TYRP1, DTC, TRPM1 and CAMK2A, had significantly different levels of expression in the two skin tissues. Potential lncRNA–miRNA–gene interactions were also examined. A total of 15 lncRNAs, 11 miRNAs and 7 genes formed 23 lncRNA–miRNA–gene pairs, suggesting that complex regulatory networks of coding and non-coding genes underlie the coat color trait in Wuzhishan pigs. Our study provides a foundation for understanding how lncRNA, miRNA and genes interact to regulate coat color in black-back/white-belly pigs. We also constructed lncRNA–miRNA–gene interaction networks to elucidate the complex molecular mechanisms underlying skin physiology and melanogenesis. The results extend our knowledge about the diversity of coat color among different domestic animals and provide a foundation for studying novel mechanisms that control coat color in Chinese indigenous pigs.

Interplay between small and long non-coding RNAs in cutaneous melanoma: a complex jigsaw puzzle with missing pieces

The incidence of cutaneous melanoma (CM) has increased in the past few decades. The biology of melanoma is characterized by a complex interaction between genetic, environmental and phenotypic factors. A greater understanding of the molecular mechanisms that promote melanoma cell growth and dissemination is crucial to improve diagnosis, prognostication, and treatment of CM. Both small and long non-coding RNAs (lncRNAs) have been identified to play a role in melanoma biology; microRNA and lncRNA expression is altered in transformed melanocytes and this in turn has functional effects on cell proliferation, apoptosis, invasion, metastasis, and immune response. Moreover, specific dysregulated ncRNAs were shown to have a diagnostic or prognostic role in melanoma and to drive the establishment of drug resistance. Here, we review the current literature on small and lncRNAs with a role in melanoma, with the aim of putting into some order this complex jigsaw puzzle.

MicroRNAs and breast cancer stem cells: Potential role in breast cancer therapy

MicroRNAs (miRNAs) can control cancer and cancer stem cells (CSCs), and this topic has drawn immense attention recently. Stem cells are a tiny population of a bulk of tumor cells that have enormous potential in expansion and metastasis of the tumor. miRNA have a crucial role in the management of the function of stem cells. This role is to either promote or suppress the tumor. In this review, we investigated the function and different characteristics of CSCs and function of the miRNAs that are related to them. We also demonstrated the role and efficacy of these miRNAs in breast cancer and breast cancer stem cells (BCSC). Eventually, we revealed the metastasis, tumor formation, and their role in the apoptosis process. Also, the therapeutic potential of miRNA as an effective method for the treatment of BCSC was described. Extensive research is required to investigate the employment or suppression of these miRNAs for therapeutics approached in different cancers in the future.

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.

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.

High intensity focused ultrasound inhibits melanoma cell migration and metastasis through attenuating microRNA-21-mediated PTEN suppression

High intensity focused ultrasound (HIFU) technology is becoming a potential noninvasive treatment for solid tumor. To explore whether HIFU can be applied to treat melanoma and its metastasis, we investigated the effect of HIFU on murine melanoma model. While there was little influence on cell survival, viability or apoptosis, HIFU exposure suppressed melanoma cell migration in vitro and metastasis in vivo. The expression of microRNA-21(miR-21) was down-regulated and PTEN expression was up-regulated in response to HIFU exposure, which was in concomitant with the reduction of AKT activity. Furthermore, ectopic miR-21 expression suppressed this effect of HIFU. These results demonstrate that HIFU exposure can inhibit AKT-mediated melanoma metastasis via miR-21 inhibition to restore PTEN expression. Therefore, targeting the miR-21/PTEN/AKT pathway might be a novel strategy of HIFU in treatment of melanoma.

MicroRNA-21 antisense oligonucleotide improves the sensitivity of A375 human melanoma cell to Cisplatin: An in vitro study

This study explored Cisplatin resistance effect of microRNA-21 (miR-21) antisense oligonucleotide (AS-ODN) in human melanoma A375 cell. AS-ODN was transfected in melanoma A375 cells and Cisplatin-resistant cell line A375/CDDP, and divided into the AS-ODN, nonsense oligonucleotide (NS-ODN) and normal groups. Cell ultrastructure changes were observed through transmission electron microscope. MiR-21 AS-ODN could be tested cell growth effect in different time periods by trypan blue exclusion. MiR-21 mRNA expression change was detected by quantitative fluorescence PCR. Cell apoptosis, cycle distribution and miR-21 AS-ODN effect on proliferation and Cisplatin sensitivity were tested by flow cytometry, MTT assay, TUNEL, and Clonogenic assay. Cell apoptosis was observed after transfection 24 h with the AS-ODN group, while the NS-ODN and normal group cells had no apoptotic symptoms; Compared with the normal group, the AS-ODN group began to show obvious cell growth inhibition effect after transfection 24 h lasting 72 h (all P < 0.05), but the NS-ODN group had no significant difference (P > 0.05). miR-21 mRNA expression in the AS-ODN group was obviously decreased with rising apoptosis rate (all P < 0.05) and there was no significant difference in the NS-ODN group (P > 0.05). MiR-21 AS-ODN could remarkably increase A375 cell and A375/CDDP cell sensitivity to Cisplatin (P < 0.05), while A375 cell sensitivity to Cisplatin between the NS-ODN group and the normal group had no difference. MiR-21 AS-ODN decreased IC₅₀ and increased Cisplatin sensitivity for A375 cells and A375/CDDP cells, which would be a new target of melanoma treatment.

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.

MicroRNA‑24‑1‑5p promotes malignant melanoma cell autophagy and apoptosis via regulating ubiquitin D

The present study aimed to investigate the key roles and possible regulatory mechanism of microRNA (miR)‑24‑1‑5p in regulating the autophagy, and apoptosis of malignant melanoma cells. The expression levels of miR‑24‑1‑5p in malignant melanoma tissues were determined. Human melanoma A375 cells were transfected with miR‑24‑1‑5p mimic and control. The effects of miR‑24‑1‑5p overexpression on regulating the expressions of autophagy‑related proteins [microtubule‑associated protein 1A/1B‑light chain 3 (LC3)‑II, LC3‑I and Beclin‑1] and apoptosis‑related proteins [apoptosis regulator Bcl‑2 (Bcl‑2) and (BCL2 like 1) Bcl‑xL] were investigated. The percentage of apoptotic cells in different transfected cells was detected. In addition, luciferase reporter assays were performed to confirm whether ubiquitin D (UBD) was a target of miR‑24‑1‑5p. The effects of UBD silencing on autophagy and apoptosis were also investigated. The expression levels of janus kinase (JNK), phosphorylated (P)‑JNK, Jun proto‑oncogene AP‑1 transcription factor subunit (c‑Jun) and p‑c‑Jun were determined following the overexpression of miR‑24‑1‑5p, and UBD. In comparison with adjacent normal tissues, miR‑24‑1‑5p was significantly downregulated in malignant melanoma tissues. Overexpression of miR‑24‑1‑5p significantly increased the levels of LC3‑II/I ratio and Beclin‑1 expression, and decreased the expression levels of Bcl‑2 and Bcl‑xL. Flow cytometry also showed that miR‑24‑1‑5p overexpression promoted cell apoptosis. Moreover, UBD was confirmed as a direct target of miR‑24‑1‑5p. Silencing of UBD promoted melanoma cell autophagy and apoptosis via regulating the expression levels of related proteins. Besides, the levels of the p‑JNK/JNK and p‑c‑Jun/Jun ratios were significantly increased following miR‑24‑1‑5p overexpression, which were reversed following co‑overexpression of miR‑24‑1‑5p, and UBD. Overexpression of miR‑24‑1‑5p may target UBD, and subsequently promote the autophagy and apoptosis of malignant melanoma cells through activation of the JNK signaling pathway.

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.

Non-coding RNAs in skin cancers: An update

Skin cancers are the most common form of cancer in humans. They can largely be categorized into Melanoma and Non-melanoma skin cancers. The latter mainly includes Squamous Cell Carcinoma (SCC) and Basal Cell Carcinoma (BCC), and have a higher incidence than melanomas. There has been a recent emergence of interest in the role of non-coding RNA's in pathogenesis of skin cancers. The transcripts which lack any protein coding capacity are called non-coding RNA. These non-coding RNA are further classified based on their length; small non-coding RNA (<200 nucleotides) and long non-coding RNA (>200 nucleotides). ncRNA They are involved at multiple transcriptional, post transcriptional and epigenetic levels, modulating cell proliferation, angiogenesis, senescence and apoptosis. Their expression pattern has also been linked to metastases, drug resistance and long term prognosis. They have both diagnostic and prognostic significance for skin cancers, and can also be a target for future therapies for cutaneous malignancies. More research is needed to further utilize their potential as therapeutic targets.

MicroRNA-21 regulates the ERK/NF-κB signaling pathway to affect the proliferation, migration, and apoptosis of human melanoma A375 cells by targeting SPRY1, PDCD4, and PTEN

This study aims to explore the effects of microRNA-21 (miR-21) and ERK/NF-κB signaling pathway on human melanoma A375 cells. The melanoma tissues and adjacent normal tissues were obtained from 45 melanoma patients. qRT-PCR was conducted to quantify the expression of miR-21 and the gene mRNA expressions. Human melanoma A375 cells were divided into the Mock, negative control (NC), miR-21 inhibitors, miR-21 inhibitors + siRNA-SPRY1, miR-21 inhibitors + siRNA-PDCD4, and miR-21 inhibitors + siRNA-PTEN groups. Western blotting was used to determine protein expressions. CCK8 assay and Transwell assay were performed to evaluate the proliferation, migration, and invasion of A375 cells. Annexin V/propidium iodide double staining was adopted to detect cell apoptosis. MiR-21 expression was higher in melanoma tissues than in adjacent tissues, while the mRNA and protein expressions of SPRY1, PDCD4, and PTEN were lower in melanoma tissues than in adjacent tissues. Compared with the Mock and NC groups, the miR-21 inhibitors group exhibited increased expressions of SPRY1, PDCD4, and PTEN and decreased expressions of ERK, p-ERK, NF-κB p65, and p-NF-κB p65. After transfection of miR-21 inhibitors, the proliferation, migration, and invasion of A375 cells were inhibited, while the apoptosis of A375 cells was promoted. However, the effects of miR-21 inhibitors on the growth, migration, invasion, and apoptosis of A375 cells were reversed after transfection of siRNA-SPRY1, siRNA-PDCD4, or siRNA-PTEN. MiR-21 can promote the proliferation, migration, and inhibit the apoptosis of human melanoma A375 cells by inhibiting SPRY1, PDCD4, and PTEN via ERK/NF-κB signaling pathway. © 2016 Wiley Periodicals, Inc.

Global microRNA profiling for diagnostic appraisal of melanocytic Spitz tumors

BACKGROUND

Melanoma skin cancer remains the leading cause of skin cancer-related deaths. Spitz lesions represent a subset of melanocytic skin lesions characterized by epithelioid or spindled melanocytes organized in nests. These lesions occupy a spectrum ranging from benign Spitz and atypical Spitz lesions all the way to malignant Spitz tumors. Appropriate management is reliant on accurate diagnostic classification, yet this effort remains challenging using current light microscopic techniques. The discovery of novel biomarkers such as microRNAs (miR) may ultimately be a useful diagnostic adjunct for the evaluation of Spitz lesions. miR expression profiles have been suggested for non-Spitz melanomas but have yet to be ascribed to Spitz lesions. We hypothesized that distinct miR expression profiles would be associated with different lesions along the Spitz spectrum.

MATERIALS AND METHODS

RNAs extracted from paraffin-embedded, formalin-fixed tissues of 11 resected skin lesions including benign nevi (n = 2), benign Spitz lesions (n = 3), atypical Spitz lesions (n = 3), and malignant Spitz tumors (n = 3) were analyzed by the NanoString platform for simultaneous evaluation of over 800 miRs in each patient sample.

RESULTS

Benign Spitz lesions had increased expression of miR-21-5p and miR-363-3p compared with those of benign nevi. Malignant Spitz lesions exhibited overexpression of miR-21-5p, miR-155-5p, and miR-1283 relative to both benign nevi and benign Spitz tumors. Notably, atypical Spitz tumors had increased expression of miR-451a and decreased expression of miR-155-5p expression relative to malignant Spitz lesions. Conversely, atypical Spitz lesions had increased expression of miR-21-5p, miR-34a-5p, miR-451a, miR-1283, and miR-1260a relative to benign Spitz tumors.

CONCLUSIONS

Overall, distinct miR profiles are suggested among Spitz lesions of varying malignant potential with some similarities to non-Spitz melanoma tumors. This work demonstrates the feasibility of this analytic method and forms the basis for further validation studies.

MicroRNA-21a-5p Functions on the Regulation of Melanogenesis by Targeting Sox5 in Mouse Skin Melanocytes

MicroRNAs (miRNAs) play an important role in regulating almost all biological processes. miRNAs bind to the 3′ untranslated region (UTR) of mRNAs by sequence matching. In a previous study, we demonstrated that miR-21 was differently expressed in alpaca skin with different hair color. However, the molecular and cellular mechanisms for miR-21 to regulate the coat color are not yet completely understood. In this study, we transfected miR-21a-5p into mouse melanocytes and demonstrated its function on melanogenesis of miR-21a-5p by targeting Sox5, which inhibits melanogenesis in mouse melanocytes. The results suggested that miR-21a-5p targeted Sox5 gene based on the binding site in 3′ UTR of Sox5 and overexpression of miR-21a-5p significantly down-regulated Sox5 mRNA and protein expression. Meanwhile, mRNA and protein expression of microphthalmia transcription factor (MITF) and Tyrosinase (TYR) were up-regulated, which subsequently make the melanin production in melanocytes increased. The results suggest that miR-21a-5p regulates melanogenesis via MITF by targeting Sox5.

MicroRNA dysregulation in melanoma

Melanoma is the deadliest form of skin cancer. Current challenges facing the management of melanoma include accurate prediction of individuals who will respond to adjuvant therapies as well as early detection of recurrences. These and other challenges have prompted investigation into biomarkers that could be used as diagnostic, prognostic and therapeutic aids. MicroRNAs (miRs) are small 19-22 nucleotide RNA inhibitors of protein translation. Over 800 different miRs are present within cells and importantly miR expression profiles may vary across different cells types and stages of malignancy. Unique expression profiles have been described for malignant melanoma; however, this work has yet to be translated into routine clinical practice. We highlight pertinent studies involving common miRs implicated in the oncogenesis of melanoma including miR-21, miR-125b, miR-150, miR-155, miR-205, and miR-211. In particular, emphasis is placed upon differential expression across different stages of melanoma progression, prognostic implications and potential mechanistic involvement. Focused efforts on inhibition of these miRs could be the most efficient method of translating preclinical endeavors into clinically meaningful applications.

Reciprocal interplay between thyroid hormone and microRNA-21 regulates hedgehog pathway-driven skin tumorigenesis

The thyroid hormone-inactivating (TH-inactivating) enzyme type 3 iodothyronine deiodinase (D3) is an oncofetal protein that is rarely expressed in adult life but has been shown to be reactivated in the context of proliferation and neoplasms. D3 terminates TH action within the tumor microenvironment, thereby enhancing cancer cell proliferation. However, the pathological role of D3 and the contribution of TH metabolism in cancer have yet to be fully explored. Here, we describe a reciprocal regulation between TH action and the cancer-associated microRNA-21 (miR21) in basal cell carcinoma (BCC) skin tumors. We found that, besides being negatively regulated by TH at the transcriptional level, miR21 attenuates the TH signal by increasing D3 levels. The ability of miR21 to positively regulate D3 was mediated by the tumor suppressor gene GRHL3, a hitherto unrecognized D3 transcriptional inhibitor. Finally, in a BCC mouse model, keratinocyte-specific D3 depletion markedly reduced tumor growth. Together, our results establish TH action as a critical hub of multiple oncogenic pathways and provide functional and mechanistic evidence of the involvement of TH metabolism in BCC tumorigenesis. Moreover, our results identify a miR21/GRHL3/D3 axis that reduces TH in the tumor microenvironment and has potential to be targeted as a therapeutic approach to BCC.

Update on melanoma epigenetics

PURPOSE OF REVIEW

Over the last years, our understanding in molecular biology of melanoma has grown significantly and many genetic alterations have been identified affecting melanoma pathogenesis. This growing evidence has led to the development of targeted therapies which are showing promising clinical results. In addition to genetic alterations, an increasing number of studies have recently demonstrated the role of epigenetics in melanoma development and progression. Here, we summarize the current data on epigenetic research in melanoma.

RECENT FINDINGS

MicroRNA (miRNA) expression profiling studies have identified several miRNAs implicated in melanoma cell cycle and proliferation, cell migration and invasion, as well as miRNAs involved in apoptosis and immune response. Abnormal methylation profiling has been associated with melanoma progression and to date aberrant hypermethylation in more than 70 genes has been described. Recent works have highlighted the increasing evidence of the role of histone modification as a central regulatory event in melanoma pathogenesis.

SUMMARY

Many of these epigenetic biomarkers may have potential diagnostic, prognostic and therapeutic implications. Future approach might be using a combination of genetic and epigenetic biomarkers.

miR-339-3p Is a Tumor Suppressor in Melanoma

Determinants of invasion and metastasis in cancer remain of great interest to define. Here, we report the definition of miR-339-3p as a novel tumor suppressive microRNA that blocks melanoma cell invasion without affecting cell survival. miR-339-3p was identified by a comprehensive functional screen of a human miRNA mimetic library in a cell-based assay for invasion by the melanoma cell line A375. miR-339-3p was determined as a strong inhibitor of invasion differentially expressed in melanoma cells and healthy melanocytes. MCL1 was defined as a target for downregulation by miR-339-3p, functioning through direct interaction with the 3' untranslated region of MCL1 mRNA. Blocking miR-339-3p by an antagomiR was sufficient to increase melanoma cell invasion, an effect that could be phenocopied by RNAi-mediated silencing of MCL1. In vivo studies established that miR-339-3p overexpression was sufficient to decrease lung colonization by A375 melanoma cells in NSG mice, relative to control cells. Overall, our results defined miR-339-3p as a melanoma tumor suppressor, the levels of which contributes to invasive aggressiveness. Cancer Res; 76(12); 3562-71. ©2016 AACR.

Major apoptotic mechanisms and genes involved in apoptosis

As much as the cellular viability is important for the living organisms, the elimination of unnecessary or damaged cells has the opposite necessity for the maintenance of homeostasis in tissues, organs and the whole organism. Apoptosis, a type of cell death mechanism, is controlled by the interactions between several molecules and responsible for the elimination of unwanted cells from the body. Apoptosis can be triggered by intrinsically or extrinsically through death signals from the outside of the cell. Any abnormality in apoptosis process can cause various types of diseases from cancer to auto-immune diseases. Different gene families such as caspases, inhibitor of apoptosis proteins, B cell lymphoma (Bcl)-2 family of genes, tumor necrosis factor (TNF) receptor gene superfamily, or p53 gene are involved and/or collaborate in the process of apoptosis. In this review, we discuss the basic features of apoptosis and have focused on the gene families playing critical roles, activation/inactivation mechanisms, upstream/downstream effectors, and signaling pathways in apoptosis on the basis of cancer studies. In addition, novel apoptotic players such as miRNAs and sphingolipid family members in various kind of cancer are discussed.

microRNA-10b is a prognostic biomarker for melanoma

Malignant melanoma is an aggressive form of skin cancer. Recently, drug therapy of advanced disease has been revolutionized by new agents. More therapeutic options, coupled with the desire to extend treatment to the adjuvant setting mean that prognostic biomarkers that can be assayed from formalin-fixed paraffin-embedded clinical would be valuable. microRNAs have potential to fill this need. We analyzed 377 microRNAs in 79 primary melanomas and 32 metastases using a split sample discovery strategy. From a discovery analysis using 40 thick primary melanomas (20 cases with metastasis and 20 controls without metastasis at 5 years), microRNA expression was measured by quantitative RT-PCR (QRT-PCR). MiR-10b emerged as a candidate prognostic microRNA. This was confirmed in an independent validation set of thick primary melanomas (20 cases with metastasis and 19 controls without metastasis at 5 years). In the combined discovery and validation cohorts (n=79), miR-10b expression showed a 3.7-fold increase in expression between cases and controls (P=0.005) and showed a trend of increasing expression between primary melanomas and their matched metastases (P<0.001). In situ hybridization showed expression was in melanoma cells and correlated with expression measured by QRT-PCR (P=0.0005). We used the combined discovery and validation samples to verify the prognostic value of additional candidate microRNAs identified from other studies, and proceeded to analyze miR-200b. We demonstrated that miR-10b and miR-200b showed independent prognostic value (P=0.002 and 0.047, respectively) in multivariable analysis alongside known clinico-pathological prognostic features (eg, Breslow thickness) using a Cox proportional hazards regression model. Furthermore, the addition of these microRNAs to the clinico-pathological features led to an improved regression model with better identification of aggressive thick melanomas. Taken together, these data suggest that miR-10b is a new prognostic microRNA for melanoma and that there could be a place for microRNA analysis in stratifying melanoma for therapy.

Expression and clinicopathological significance of microRNA-21 and programmed cell death 4 in malignant melanoma

OBJECTIVE

To measure levels of microRNA (miR)-21 and its target gene, programmed cell death 4 (PDCD4), in samples of human cutaneous malignant melanoma and normal non-malignant control skin.

METHODS

Relative levels of miR-21 and PDCD4 mRNA were measured using a quantitative real-time reverse transcription-polymerase chain reaction. Correlations between the levels of the two molecules and the clinicopathological characteristics of malignant melanoma were analysed.

RESULTS

A total of 67 cases of human cutaneous malignant melanoma were analysed and compared with 67 samples of normal nonmalignant control skin. Compared with normal skin samples, the relative level of miR-21 was significantly higher and the relative level of PDCD4 mRNA was significantly lower in the melanoma specimens. A significant negative correlation between PDCD4 mRNA and miR-21 was demonstrated in malignant melanoma (r = -0.602). Elevated miR-21 and reduced PDCD4 mRNA levels were both significantly correlated with increased tumour size, a higher Clark classification level and the presence of lymph node metastases in malignant melanoma.

CONCLUSIONS

These findings suggest that miR-21 and PDCD4 might be potential biomarkers for malignant melanoma and might provide treatment targets in the future.

MiR-21: an environmental driver of malignant melanoma?

Since the mid-1950’s, melanoma incidence has been rising steadily in industrialized Caucasian populations, thereby pointing to the pivotal involvement of environmental factors in melanomagenesis. Recent evidence underlines the crucial role of microRNA (miR) signaling in cancer initiation and progression. Increased miR-21 expression has been observed during the transition from a benign melanocytic lesion to malignant melanoma, exhibiting highest expression of miR-21. Notably, common BRAF and NRAS mutations in cutaneous melanoma are associated with increased miR-21 expression. MiR-21 is an oncomiR that affects critical target genes of malignant melanoma, resulting in sustained proliferation (PTEN, PI3K, Sprouty, PDCD4, FOXO1, TIPE2, p53, cyclin D1), evasion from apoptosis (FOXO1, FBXO11, APAF1, TIMP3, TIPE2), genetic instability (MSH2, FBXO11, hTERT), increased oxidative stress (FOXO1), angiogenesis (PTEN, HIF1α, TIMP3), invasion and metastasis (APAF1, PTEN, PDCD4, TIMP3). The purpose of this review is to provide translational evidence for major environmental and individual factors that increase the risk of melanoma, such as UV irradiation, chemical noxes, air pollution, smoking, chronic inflammation, Western nutrition, obesity, sedentary lifestyle and higher age, which are associated with increased miR-21 signaling. Exosomal miR-21 induced by extrinsic and intrinsic stimuli may be superimposed on mutation-induced miR-21 pathways of melanoma cells. Thus, oncogenic miR-21 signaling may be the converging point of intrinsic and extrinsic stimuli driving melanomagenesis. Future strategies of melanoma treatment and prevention should thus aim at reducing the burden of miR-21 signal transduction.

An updated review of mechanotransduction in skin disorders: transcriptional regulators, ion channels, and microRNAs

INTRODUCTION

The skin is constantly exposed and responds to a wide range of biomechanical cues. The mechanobiology of skin has already been known and applied by clinicians long before the fundamental molecular mechanisms of mechanotransduction are elucidated.

MATERIALS AND METHODS

Despite increasing knowledge on the mediators of biomechanical signaling such as mitogen-associated protein kinases, Rho GTPases or FAK-ERK pathways, the key elements of mechano-responses transcription factors, and mechano-sensors remain unclear. Recently, canonical biochemical components of Hippo and Wnt signaling pathway YAP and β-catenin were found to exhibit undefined mechanical sensitivity. Mechanical forces were identified to be the dominant regulators of YAP/TAZ activity in a multicellular context. Furthermore, different voltage or ligand sensitive ion channels in the cell membrane exhibited their mechanical sensitivity as mechano-sensors. Additionally, a large number of microRNAs have been confirmed to regulate cellular behavior and contribute to various skin disorders under mechanical stimuli. Mechanosensitive (MS) microRNAs could not only be activated by distinct mechanical force pattern, but also responsively target MS sensors such as e-cadherin and cytoskeleton constituent RhoA.

CONCLUSION

Thus, a comprehensive understanding of this regulatory network of cutaneous mechanotransduction will facilitate the development of novel approaches to wound healing, hypertrophic scar formation, skin regeneration, and the progression or initiation of skin diseases.

Oncogenic and tumor suppressive roles of microRNAs in apoptosis and autophagy

MicroRNAs (miRNAs), small and non-coding endogenous RNAs ∼22 nucleotides (nt) in length, have been known to regulate approximately 30 % of human gene expression at the post-transcriptional and translational levels. Accumulating data have demonstrated that certain miRNAs could exert an oncogenic and/or tumor suppressive function and might play essential roles in the regulation of apoptosis and autophagy in cancer. In this review, we summarize that certain oncogenic and tumor suppressive miRNAs could modulate apoptotic pathways in different types of cancer. Subsequently, we demonstrate that other miRNAs might play regulatory roles in the autophagic pathways of cancer. A limited number of oncogenic/tumor suppressive miRNAs could regulate apoptosis and autophagy, respectively, and cooperatively. Taken together, these findings would provide a new clue to elucidate more apoptotic and/or autophagic mechanisms of miRNAs for designing potential novel therapeutic strategies in cancer.

MicroRNAs in B-cells: from normal differentiation to treatment of malignancies

MicroRNAs (miRNAs) are small non-coding RNAs that play important post-transcriptional regulatory roles in a wide range of biological processes. They are fundamental to the normal development of cells, and evidence suggests that the deregulation of specific miRNAs is involved in malignant transformation due to their function as oncogenes or tumor suppressors. We know that miRNAs are involved in the development of normal B-cells and that different B-cell subsets express specific miRNA profiles according to their degree of differentiation. B-cell-derived malignancies contain transcription signatures reminiscent of their cell of origin. Therefore, we believe that normal and malignant B-cells share features of regulatory networks controlling differentiation and the ability to respond to treatment. The involvement of miRNAs in these processes makes them good biomarker candidates. B-cell malignancies are highly prevalent, and the poor overall survival of patients with these malignancies demands an improvement in stratification according to prognosis and therapy response, wherein we believe miRNAs may be of great importance. We have critically reviewed the literature, and here we sum up the findings of miRNA studies in hematological cancers, from the development and progression of the disease to the response to treatment, with a particular emphasis on B-cell malignancies.

The role of microRNAs and long non-coding RNAs in the pathology, diagnosis, and management of melanoma

Melanoma is frequently lethal and its global incidence is steadily increasing. Despite the rapid development of different modes of targeted treatment, durable clinical responses remain elusive. A complete understanding of the molecular mechanisms that drive melanomagenesis is required, both genetic and epigenetic, in order to improve prevention, diagnosis, and treatment. There is increased appreciation of the role of microRNAs (miRNAs) in melanoma biology, including in proliferation, cell cycle, migration, invasion, and immune evasion. Data are also emerging on the role of long non-coding RNAs (lncRNAs), such as SPRY4-IT1, BANCR, and HOTAIR, in melanomagenesis. Here we review the data on the miRNAs and lncRNAs implicated in melanoma biology. An overview of these studies will be useful for providing insights into mechanisms of melanoma development and the miRNAs and lncRNAs that might be useful biomarkers or future therapeutic targets.

Cytochromes p450 and skin cancer: role of local endocrine pathways

Skin is the largest body organ forming a metabolically active barrier between external and internal environments. The metabolic barrier is composed of cytochromes P450 (CYPs) that regulate its homeostasis through activation or inactivation of biologically relevant molecules. In this review we focus our attention on local steroidogenic and secosteroidogenic systems in relation to skin cancer, e.g., prevention, attenuation of tumor progression and therapy. The local steroidogenic system is composed of locally expressed CYPs involved in local production of androgens, estrogens, gluco- and mineralo-corticosteroids from cholesterol (initiated by CYP11A1) or from steroid precursors delivered to the skin, and of their metabolism and/or inactivation. Cutaneous 7-hydroxylases (CYP7A1, CYP7B1 and CYP39) potentially can produce 7-hydroxy/oxy-steroids/sterols with modifying effects on local tumorigenesis. CYP11A1 also transforms 7-dehydrocholesterol (7DHC)→22(OH)7DHC→20,22(OH)2-7DHC→7-dehydropregnenolone, which can be further metabolized to other 5,7- steroidal dienes. These 5,7-dienal intermediates are converted by ultraviolet radiation B (UVB) into secosteroids which show pro-differentiation and anti-cancer properties. Finally, the skin is the site of activation of vitamin D3 through two alternative pathways. The classical one involves sequential hydroxylation at positions 25 and 1 to produce active 1,25(OH)2D3, which is further inactivated through hydroxylation at C24. The novel pathway is initiated by CYP11A1 with predominant production of 20(OH)D3 which is further metabolized to biologically active but non-calcemic D3-hydroxyderivatives. Classical and non-classical (novel) vitamin D analogs show pro-differentiation, anti-proliferative and anticancer properties. In addition, melatonin is metabolized by local CYPs. In conclusion cutaneously expressed CYPs have significant effects on skin physiology and pathology trough regulation of its chemical milieu.

Melanoma epigenetics: novel mechanisms, markers, and medicines

The incidence and mortality rates of cutaneous melanoma continue to increase worldwide, despite the deployment of targeted therapies. Recently, there has been rapid growth and development in our understanding of epigenetic mechanisms and their role in cancer pathobiology. Epigenetics--defined as the processes resulting in heritable changes in gene expression beyond those caused by alterations in the DNA sequence--likely contain the information that encodes for such phenotypic variation between individuals with identical genotypes. By altering the structure of chromatin through covalent modification of DNA bases or histone proteins, or by regulating mRNA translation through non-coding RNAs, the epigenome ultimately determines which genes are expressed and which are kept silent. While our understanding of epigenetic mechanisms is growing at a rapid pace, the field of melanoma epigenomics still remains in its infancy. In this Pathology in Focus, we will briefly review the basics of epigenetics to contextualize and critically examine the existing literature using melanoma as a cancer paradigm. Our understanding of how dysregulated DNA methylation and DNA demethylation/hydroxymethylation, histone modification, and non-coding RNAs affect cancer pathogenesis and melanoma virulence, in particular, provides us with an ever-expanding repertoire of potential diagnostic biomarkers, therapeutic targets, and novel pathogenic mechanisms. The evidence reviewed herein indicates the critical role of epigenetic mechanisms in melanoma pathobiology and provides evidence for future targets in the development of next-generation biomarkers and therapeutics.