Function and Clinical Implications of Long Non-Coding RNAs in Melanoma

Non-coding RNAs in BRAF-mutant melanoma: targets, indicators, and therapeutic potential

Melanoma, a highly aggressive skin cancer, is often driven by BRAF mutations, such as the V600E mutation, which promotes cancer growth through the MAPK pathway and contributes to treatment resistance. Understanding the role of non-coding RNAs (ncRNAs) in these processes is crucial for developing new therapeutic strategies. This review aims to elucidate the relationship between ncRNAs and BRAF mutations in melanoma, focusing on their regulatory roles and impact on treatment resistance. We comprehensively reviewed current literature to synthesize evidence on ncRNA-mediated regulation of BRAF-mutant melanoma and their influence on therapeutic responses. Key ncRNAs, including microRNAs and long ncRNAs, were identified as significant regulators of melanoma development and therapy resistance. MicroRNAs such as miR-15/16 and miR-200 families modulate critical pathways like Wnt signaling and melanogenesis. Long ncRNAs like ANRIL and SAMMSON play roles in cell growth, invasion, and drug susceptibility. Specific ncRNAs, such as BANCR and RMEL3, intersect with the MAPK pathway, highlighting their potential as therapeutic targets or biomarkers in BRAF-mutant melanoma. Additionally, ncRNAs involved in drug resistance, such as miR-579-3p and miR-1246, target processes like autophagy and immune checkpoint regulation. This review highlights the pivotal roles of ncRNAs in regulating BRAF-mutant melanoma and their contribution to drug resistance. These findings underscore the potential of ncRNAs as biomarkers and therapeutic targets, paving the way for innovative treatments to improve outcomes for melanoma patients.

Transcriptional landscape of long non-coding RNAs (lncRNAs) and its implication in viral diseases

Long non-coding RNAs (lncRNAs) are RNA transcripts of size >200 bp that do not translate into proteins. Emerging data revealed that viral infection results in systemic changes in the host at transcriptional level. These include alterations in the lncRNA expression levels and triggering of antiviral immune response involving several effector molecules and diverse signalling pathways. Thus, lncRNAs have emerged as an essential mediatory element at distinct phases of the virus infection cycle. The complete eradication of the viral disease requires more precise and novel approach, thus manipulation of the lncRNAs could be one of them. This review shed light upon the existing knowledge of lncRNAs wherein the implication of differentially expressed lncRNAs in blood-borne, air-borne, and vector-borne viral diseases and its promising therapeutic applications under clinical settings has been discussed. It further enhances our understanding of the complex interplay at host-pathogen interface with respect to lncRNA expression and function.

Comprehensive prediction of immune microenvironment and hot and cold tumor differentiation in cutaneous melanoma based on necroptosis-related lncRNA

As per research, causing cancer cells to necroptosis might be used as a therapy to combat cancer drug susceptibility. Long non-coding RNA (lncRNA) modulates the necroptosis process in Skin Cutaneous Melanoma (SKCM), even though the precise mechanism by which it does so has yet been unknown. RNA sequencing and clinical evidence of SKCM patients were accessed from The Cancer Genome Atlas database, and normal skin tissue sequencing data was available from the Genotype-Tissue Expression database. Person correlation analysis, differential screening, and univariate Cox regression were successively utilized to identify necroptosis-related hub lncRNAs. Following this, we adopt the least absolute shrinkage and selection operator regression analysis to construct a risk model. The model was evaluated on various clinical characteristics using many integrated approaches to ensure it generated accurate predictions. Through risk score comparisons and consistent cluster analysis, SKCM patients were sorted either high-risk or low-risk subgroups as well as distinct clusters. Finally, the effect of immune microenvironment, m7G methylation, and viable anti-cancer drugs in risk groups and potential clusters was evaluated in further detail. Included USP30-AS1, LINC01711, LINC00520, NRIR, BASP1-AS1, and LINC02178, the 6 necroptosis-related hub lncRNAs were utilized to construct a novel prediction model with excellent accuracy and sensitivity, which was not influenced by confounding clinical factors. Immune-related, necroptosis, and apoptosis pathways were enhanced in the model structure, as shown by Gene Set Enrichment Analysis findings. TME score, immune factors, immune checkpoint-related genes, m7G methylation-related genes, and anti-cancer drug sensitivity differed significantly between the high-risk and low-risk groups. Cluster 2 was identified as a hot tumor with a better immune response and therapeutic effect. Our study may provide potential biomarkers for predicting prognosis in SKCM and provide personalized clinical therapy for patients based on hot and cold tumor classification.

Long Noncoding RNA SAMMSON Promotes Melanoma Progression by Inhibiting FOXA2 Expression

Long noncoding RNAs (lncRNAs) play crucial roles in melanoma initiation and development, serving as potential therapeutic targets and prognostic markers for melanoma. lncRNA survival-associated mitochondrial melanoma-specific oncogenic noncoding RNA (SAMMSON) is upregulated in many types of human cancers. However, the functions of SAMMSON in melanoma have not been fully elucidated. This study is aimed at investigating the expression and functions of SAMMSON in melanoma development. Bioinformatics analysis was performed to determine the expression of SAMMSON and its correlation with the 10-year overall survival (OS) in melanoma patients. Cell proliferation, migration, invasion, and tumorigenesis were detected by MTT, colony formation, Transwell assays, and mouse xenograft model. The expression of cell cycle-related factors, epithelial-to-mesenchymal transition (EMT) makers, and matrix metalloproteinases (MMPs) was assessed by RT-qPCR and western blotting analysis. The results demonstrated that SAMMSON expression was upregulated in melanoma tissues and cells, and lower SAMMSON expression was correlated with longer 10-year OS. SAMMSON knockdown decreased the proliferation, migration, and invasion of melanoma cells by regulating the expression of proliferation-related genes, EMT factors, and MMPs, respectively. Additionally, Forkhead box protein A2 (FOXA2) was confirmed to be a target of SAMMSON, and the biological effects induced by FOXA2 overexpression were similar to those induced by SAMMSON silencing in melanoma cells. Further studies showed that SAMMSON downregulated FOXA2 expression in melanoma cells by modulating the EZH2/H3K27me3 axis. Taken together, our data indicate that SAMMSON plays an important role in melanoma progression and can be a valuable biomarker and therapeutic target in melanoma.

Regulation of the TUG1/miR‑145‑5p/SOX2 axis on the migratory and invasive capabilities of melanoma cells

Melanoma is the most prevalent malignancy of cutaneous carcinomas. Taurine-upregulated gene 1 (TUG1), a lncRNA, is a pivotal regulator of cutaneous malignancies. The present study aimed to investigate the impact and possible mechanisms of action of TUG1 behind the progression of melanomas. Reverse transcription-quantitative PCR was conducted to detect the expression levels of TUG1, microRNA (miR)-145-5p and SOX2 in melanoma tissues and cell lines. Cell Counting Kit-8 (CCK-8) assays were performed to measure the proliferative ability of melanoma cells and transwell assays were used to examine the migration and invasion of melanoma cells. Dual luciferase reporter and RNA immunoprecipitation (RIP) assays were utilized to identify the interactions among TUG1, miR-145-5p and SOX2. Western blotting and immunohistochemical assays were performed to determine the expression profile of SOX2. The impact of TUG1 on melanoma tumorigenesis was assessed using tumorigenicity assays. TUG1 expression levels were elevated in melanoma tumor tissues and cell lines. Reduced TUG1 expression levels significantly inhibited the proliferative, migratory and invasive abilities of melanoma cells. The expression levels of miR-145-5p were decreased in melanoma tumor tissues and cell lines. TUG1 directly targeted miR-145-5p and downregulated miR-145-5p. Upregulation of TUG1 counteracted the promotion of the proliferative, migratory and invasive abilities of melanoma cells induced by the overexpression of miR-145-5p. SOX2 was a target of miR-145-5p and its expression was negatively regulated by miR-145-5p, while positively regulated by TUG1. TUG1 regulated SOX2 expression through sponging miR-145-5p. Silencing of TUG1 also inhibited melanoma tumorigenesis in mice. In conclusion, the TUG1/miR-145-5p/SOX2 axis regulated the migration and invasion of melanoma cells.

Emerging role of lncRNA ELDR in development and cancer

Whole-genome sequencing and transcriptome analysis revealed more than 90% of the human genome transcribes noncoding RNAs including lncRNAs. From the beginning of the 21st century, lncRNAs have gained widespread attention as a new layer of regulation in biological processes. lncRNAs are > 200 nucleotides in size, transcribed by RNA polymerase II, and share many similarities with mRNAs. lncRNA interacts with DNA, RNA, protein, and miRNAs, thereby regulating many biological processes. In this review, we have focused mainly on LINC01156 [also known as the EGFR long non-coding downstream RNA (ELDR) or Fabl] and its biological importance. ELDR is a newly identified lncRNA and first reported in a mouse model, but it has a human homolog. The human ELDR gene is closely localized downstream of epidermal growth factor receptor (EGFR) gene at chromosome 7 on the opposite strand. ELDR is highly expressed in neuronal stem cells and associated with neuronal differentiation and mouse brain development. ELDR is upregulated in head and neck cancer, suggesting its role as an oncogene and its importance in prognosis and therapy. Publicly available RNA-seq data further support its oncogenic potential in different cancers. Here, we summarize all the aspects of ELDR in development and cancer, highlighting its future perspectives in the context of mechanism.

Potential Biological Roles of Exosomal Long Non-Coding RNAs in Gastrointestinal Cancer

Exosomes, a type of extracellular vesicles (EVs), are secreted by almost all cells and contain many cellular constituents, such as nucleic acids, lipids, and metabolites. In addition, they play a crucial role in intercellular communication and have been proved to be involved in the development and treatment of gastrointestinal cancer. It has been confirmed that long non-coding RNAs (lncRNAs) exert a range of biological functions, such as cell metastasis, tumorigenesis, and therapeutic responses. This review mainly focused on the emerging roles and underlying molecular mechanisms of exosome-derived lncRNAs in gastrointestinal cancer in recent years. The biological roles of exosomal lncRNAs in the pathogenesis and therapeutic responses of gastrointestinal cancers were also investigated.

The pleiotropic roles of circular and long noncoding RNAs in cutaneous melanoma

Cutaneous melanoma (CM) is a very aggressive disease, often characterized by unresponsiveness to conventional therapies and high mortality rates worldwide. The identification of the activating BRAFV600 mutations in approximately 50% of CM patients has recently fueled the development of novel small-molecule inhibitors that specifically target BRAFV600 -mutant CM. In addition, a major progress in CM treatment has been made by monoclonal antibodies that regulate the immune checkpoint inhibitors. However, although target-based therapies and immunotherapeutic strategies have yielded promising results, CM treatment remains a major challenge. In the last decade, accumulating evidence points to the aberrant expression of different types of noncoding RNAs (ncRNAs) in CM. While studies on microRNAs have grown exponentially leading to significant insights on CM biology, the role of circular RNAs (circRNAs) and long noncoding RNAs (lncRNAs) in this tumor is less understood, and much remains to be discovered. Here, we summarize and critically review the available evidence on the molecular functions of circRNAs and lncRNAs in BRAFV600 -mutant CM and CM immunogenicity, providing recent updates on their functional role in targeted therapy and immunotherapy resistance. In addition, we also include an evaluation of several algorithms and databases for prediction and validation of circRNA and lncRNA functional interactions.

High expression of lncRNA HSD11B1-AS1 indicates favorable prognosis and is associated with immune infiltration in cutaneous melanoma

Cutaneous melanoma is an aggressive malignant cancer associated with poor prognosis. Identification of reliable biomarkers for predicting prognosis of melanoma contributes to improved clinical outcome and disease management. Long non-coding RNAs (lncRNAs) serve a crucial regulatory role of oncogenesis and tumor suppression in melanoma. Using data from The Cancer Genome Atlas database, novel lncRNA 11β-hydroxysteroid dehydrogenase type 1-antisense RNA 1 (HSD11B1-AS1) was identified, which was significantly downregulated in malignant melanoma and its downregulation was significantly associated with poor clinicopathological characteristics, including advanced T and pathological stage, Clark level, Breslow depth and ulceration and worse prognosis. Multivariate analysis showed that HSD11B1-AS1, as well as N stage and Breslow depth, were independent prognostic factors in cutaneous melanoma, and nomograms suggested a good predictive value of 1-, 3- and 5-year overall survival, progression-free interval and disease-specific survival. In vitro experiments verified the decreased HSD11B1-AS1 expression in melanoma cell lines compared with human epidermal melanocytes. Moreover, cell experiments in vitro, including Cell Counting Kit-8, colony formation, wound healing and Transwell assay, suggested that overexpression of HSD11B1-AS1 significantly inhibited melanoma cell proliferation, migration and invasion. Functional enrichment showed significantly enriched pathways in IFN-γ and -α response, TNF-α signaling via NF-κB and IL-2/STAT-5 and IL-6/JAK/STAT-3 signaling. In addition, immune infiltration analysis demonstrated that HSD11B1-AS1 may function by accelerating immune response regulation and the immune cell infiltration of various immunocytes, especially T, T helper 1, activated dendritic and B cells. The present study revealed HSD11B1-AS1 as a potential therapeutic target and promising biomarker for diagnosis and prognosis of cutaneous melanoma.

Metformin pretreatment reduces effect to dacarbazine and suppresses melanoma cell resistance

Oxidative stress role on metformin process of dacarbazine (DTIC) inducing resistance of B16F10 melanoma murine cells are investigated. To induce resistance to DTIC, murine melanoma cells were exposed to increasing concentrations of dacarabazine (DTIC-res group). Metformin was administered before and during the induction of resistance to DTIC (MET-DTIC). The oxidative stress parameters of the DTIC-res group showed increased levels of malondialdehyde (MDA), thiol, and reduced nuclear p53, 8-hydroxy-2'-deoxyguanosine (8-OH-DG), nuclear factor kappa B (NF-ĸB), and Nrf2. In presence of metformin in the resistant induction process to DTIC, (MET-DTIC) cells had increased antioxidant thiols, MDA, nuclear p53, 8-OH-DG, Nrf2, and reducing NF-ĸB, weakening the DTIC-resistant phenotype. The exclusive administration of metformin (MET group) also induced the cellular resistance to DTIC. The MET group presented high levels of total thiols, MDA, and reduced percentage of nuclear p53. It also presented reduced nuclear 8-OH-DG, NF-ĸB, and Nrf2 when compared with the control. Oxidative stress and the studied biomarkers seem to be part of the alterations evidenced in DTIC-resistant B16F10 cells. In addition, metformin administration is able to play a dual role according to the experimental protocol, preventing or inducing a DTIC-resistant phenotype. These findings should help future research with the aim of investigating DTIC resistance in melanoma.

LINC00511 as a prognostic biomarker for human cancers: a systematic review and meta-analysis

BACKGROUND

Long intergenic non-coding RNA 00511 (LINC00511) is highly expressed in diverse cancers and has a correlation with poor clinical outcomes for cancer patients. In view of contradictory data among published data, we aim to evaluate the prognostic role of LINC00511 for cancer patients.

METHODS

In the present study, a meta-analysis of related studies has been performed to investigate the prognostic significance of LINC00511 in cancer patients. Relevant studies published before December 22, 2019 were systematically searched online in PubMed, EMBASE, Web of Science, and the Cochrane Library databases. The relationship between LINC00511 expression and cancer patients' survival, including overall survival (OS), disease-free survival (DFS)/relapse-free survival (RFS) and progression-free survival (PFS), was evaluated using pooled hazard ratios (HRs) with their corresponding 95% confidence intervals (CIs). The association between LINC00511 expression and clinicopathological features was assessed using odd ratios (ORs) and their corresponding 95% CIs.

RESULTS

A total of 14 eligible studies with 1883 patients were enrolled in the present meta-analysis. The results demonstrated that elevated expression of LINC00511 was significantly associated with poor OS (HR = 2.62; 95% CI: 2.00-3.45; p <  0.001), PFS (HR = 1.80; 95% CI: 1.29-2.51; p = 0.001) and DFS/RFS (HR = 2.90; 95% CI: 1.04-8.12; p = 0.04). Additionally, High LINC00511 expression was associated with large tumor size (OR = 3.10; 95% CI: 1.97-4.86; p <  0.00001), lymph node metastasis (OR = 3.11; 95% CI: 2.30-4.21; p <  0.00001), advanced clinical stage (OR = 3.95; 95% CI: 2.68-5.81; p <  0.00001), distant metastasis (OR = 2.39; 95% CI: 1.16-4.93; p = 0.02), and disease recurrence (OR = 4.62; 95% CI: 2.47-8.65; p <  0.00001). Meanwhile, no correlation was found between LINC00511 expression and age, gender, and histological grade. These findings were consolidated by the results of bioinformatics analysis.

CONCLUSIONS

Based on our findings, LINC00511 may serve as a novel prognostic biomarker for cancer patients.

Significance of 5-S-Cysteinyldopa as a Marker for Melanoma

Melanoma is one of the most lethal and malignant cancers and its incidence is increasing worldwide, and Japan is not an exception. Although there are numerous therapeutic options for melanoma, the prognosis is still poor once it has metastasized. The main concern after removal of a primary melanoma is whether it has metastasized, and early detection of metastatic melanoma would be effective in improving the prognosis of patients. Thus, it is very important to identify reliable methods to detect metastases as early as possible. Although many prognostic biomarkers (mainly for metastases) of melanoma have been reported, there are very few effective for an early diagnosis. Serum and urinary biomarkers for melanoma diagnosis have especially received great interest because of the relative ease of sample collection and handling. Several serum and urinary biomarkers appear to have significant potential both as prognostic indicators and as targets for future therapeutic methods, but still there are no efficient serum and urinary biomarkers for early detection, accurate diagnosis and prognosis, efficient monitoring of the disease and reliable prediction of survival and recurrence. Levels of 5-S-cysteinyldopa (5SCD) in the serum or urine as biomarkers of melanoma have been found to be significantly elevated earlier and to reflect melanoma progression better than physical examinations, laboratory tests and imaging techniques, such as scintigraphy and echography. With recent developments in the treatment of melanoma, studies reporting combinations of 5SCD levels and new applications for the treatment of melanoma are gradually increasing. This review summarizes the usefulness of 5SCD, the most widely used and well-known melanoma marker in the serum and urine, compares 5SCD and other useful markers, and finally its application to other fields.

p53-Regulated Long Noncoding RNA PRECSIT Promotes Progression of Cutaneous Squamous Cell Carcinoma via STAT3 Signaling

Long noncoding RNAs (lncRNAs) have emerged as putative biomarkers and therapeutic targets in cancer. The role of lncRNA LINC00346 in cutaneous squamous carcinoma (cSCC) was examined. The expression of LINC00346 was up-regulated in cSCC cells compared with normal human epidermal keratinocytes. Elevated expression of LINC00346 was noted in tumor cells in cSCC tissue sections in vivo, as compared with cSCC in situ, and actinic keratosis by RNA in situ hybridization; and the expression in seborrheic keratosis and normal skin was very low. Immunohistochemical analysis of cSCC tissue sections and functional assays of cSCC cells in culture showed that LINC00346 expression is down-regulated by p53. Knockdown of LINC00346 inhibited invasion of cSCC cells in culture and suppressed growth of human cSCC xenografts in vivo. Knockdown of LINC00346 inhibited expression of activated STAT3 and resulted in down-regulation of the expression of matrix metalloproteinase (MMP)-1, MMP-3, MMP-10, and MMP-13. Based on these observations LINC00346 was named p53 regulated carcinoma-associated STAT3-activating long intergenic non-protein coding transcript (PRECSIT). These results identify PRECSIT as a new p53-regulated lncRNA, which promotes progression of cSCC via STAT3 signaling.

Linc00961 inhibits the proliferation and invasion of skin melanoma by targeting the miR‑367/PTEN axis

Long intergenic noncoding RNA 00961 (Linc00961) has been identified as a tumor suppressor in various types of cancer. However, the critical roles of Linc00961 in the carcinogenesis and progression of skin melanoma (SM) are yet to be fully elucidated. The present study revealed via reverse transcription‑quantitative PCR analysis that Linc00961 was downregulated in the tissues of patients with SM compared with benign nevi, and in A375, A2058 and SK‑MEL‑28 cell lines compared with human melanocytes. Furthermore, overexpression of Linc00961 inhibited cell proliferation, and promoted the apoptosis of A375 and SK‑MEL‑28 cells in vitro and in vivo, as determined by Cell Counting Kit‑8 and flow cytometry assays, and tumor xenograft studies, respectively. Overexpression of Linc00961 also led to an attenuation of the migration and invasive capabilities of A375 and SK‑MEL‑28 cells, measured using Transwell assays. Functionally, it was demonstrated that Linc00961 acted as a competing endogenous RNA (ceRNA) by competitively sponging microRNA‑367 (miR‑367) in A375 and SK‑MEL‑28 cells; restoration of miR‑367 rescued the inhibitory effects of Linc00961 on A375 and SK‑MEL‑28 cells. Finally, it was observed that phosphate and tension homology deleted on chromosome 10 (PTEN), an established target of miR‑367 in A375 and SK‑MEL‑28 cells, was positively regulated by Linc00961, and its inhibition reversed the inhibitory effects of Linc00961 on the proliferation and invasion of A375 and SK‑MEL‑28 cells. Collectively, the present study revealed that Linc00961 was downregulated in SM, and furthermore, Linc00961 was identified as a ceRNA that inhibits the proliferation and invasion of A375 and SK‑MEL‑28 cells by modulating the miR‑367/PTEN axis.

Downregulation of the expression of the lncRNA MIAT inhibits melanoma migration and invasion through the PI3K/AKT signaling pathway

BACKGROUND

Long noncoding RNA MIAT expression is related to the development of some diseases. However, the role of MIAT in melanoma was has seldom been studied.

OBJECTIVE

To investigate the effect of the lncRNA MIAT on melanoma cells.

METHOD

Microarray was used to analyze the lncRNAs expression in tissue samples. The expression of the lncRNA MIAT was detected by qRT-PCR. A CCK-8 assay was used to assess cell viability, and cell counting was used to analyze cell proliferation. Wound healing and Transwell invasion assays were used to detect the migration and invasion abilities, respectively, of melanoma cells. Western blotting was performed to explore the molecular mechanisms of MIAT in melanoma.

RESULTS

The lncRNA MIAT was overexpressed in melanoma. The overexpression of MIAT promoted cell proliferation, cell invasion and migration, while the knockdown of MIAT expression got the opposite results. MIAT significantly upregulated the phosphorylation of PI3K and AKT and promoted cMyc and cyclin D1 protein expression.

CONCLUSION

LncRNA MIAT was a key factor to promote cell invasion, migration and proliferation through the PI3K/AKT signaling pathway. These findings may give us a potential way to treat melanoma.

Low level of exosomal long non-coding RNA HOTTIP is a prognostic biomarker in colorectal cancer

Molecular risk stratification of colorectal cancer can improve patient outcome. A panel of lncRNAs (H19, HOTTIP, HULC and MALAT1) derived from serum exosomes of patients with non-metastatic CRC and healthy donors was analyzed. Exosomes from healthy donors carried significantly more H19, HULC and HOTTIP transcripts in comparison to CRC patients. Correlation analysis between lncRNAs and clinical data revealed a statistical significance between low levels of exosomal HOTTIP and poor overall survival. This was confirmed by multivariate analysis that HOTTIP is an independent prognostic marker for overall survival (HR: 4.5, CI: 1.69-11.98, p = 0.0027). Here, HOTTIP poses to be a valid biomarker for patients with a CRC to predict post-surgical survival time.

LNMAT1 Promotes Invasion-Metastasis Cascade in Malignant Melanoma by Epigenetically Suppressing CADM1 Expression

The invasion-metastasis cascade is one of the most important factors relating to poor survival and prognosis of malignant melanoma (MM) patients. Long non-coding RNA lymph node metastasis associated transcript 1 (LNMAT1) is a key regulator in lymph node metastasis of multiple cancer types, but the roles and underlying mechanisms of LNMAT1 in the invasion-metastasis cascade of MM remain unclear. In the present study, we aimed to investigate the expression and function of LNMAT1 in MM. Here, we found that LNMAT1 was upregulated in MM tissues and cells, and its expression levels were further enhanced in MM patients with lymph node metastasis and metastatic MM cells. Using loss-of-function assays, we found that LNMAT1 promoted cell migration and invasion and lung metastasis in MM in vitro and in vivo. Moreover, we found that cell adhesion molecule 1 (CADM1), the established tumor suppressor in MM, was the downstream target of LNMAT1. Mechanistically, LNMAT1 epigenetically suppressed CADM1 expression by recruiting EZH2, the key regulator of trimethylation of histone H3 at lysine 27 (H3K27me3), to the CADM1 promoter, resulting in transcriptional inhibition of CADM1. Lastly, rescue assays demonstrated that LNMAT1 promoted cell migration and invasion of MM by suppressing CADM1 expression. Our findings elucidate a new mechanism for LNMAT1-mediated invasion-metastasis cascade in MM and suggest that LNMAT1 may be a new therapeutic target and prognostic predictor for MM.

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.

LncRNA SNHG5 promotes growth and invasion in melanoma by regulating the miR-26a-5p/TRPC3 pathway

INTRODUCTION

Melanoma has been reported as the most common malignancy in skin cancer. The small nucleolar RNA host gene 5 (SNHG5), an lncRNA, has been proven as a vital regulator in several types of carcinoma. This study was designed to investigate the detailed roles and possible mechanisms of SNHG5 in melanoma progression.

METHODS

Quantitative real-time PCR (qRT-PCR) analysis was conducted to detect the expression levels of SNHG5, miR-26a-5p and transient receptor potential, canonical 3 (TRPC3) mRNA in melanoma tissues and cells. CCK-8 assay was used to measure the cell viability. Flow cytometry assays were performed to determine the cell cycle distribution and apoptosis. The invasive ability was assessed by a 24-well Transwell insert. Western blot analysis was employed to evaluate the protein expression of TRPC3. Dual luciferase reporter assay, RNA immunoprecipitation (RIP) assay, and RNA pull-down assay were applied to identify the interactions among SNHG5, miR-26a-5p and TRPC3.

RESULTS

The results showed that SNHG5 expression was increased in melanoma tumor tissues and cell lines. Higher SNHG5 expression was correlated with advanced pathogenic status. Moreover, SNHG5 could serve as a molecular sponge of miR-26a-5p. SNHG5 downregulation repressed proliferation, promoted apoptosis, and decreased invasion in melanoma cells, while these effects were greatly counteracted by miR-26a-5p inhibitor. Furthermore, miR-26a-5p directly targeted TRPC3 to suppress its expression, and this effect was aggravated following SNHG5 downregulation. Also, TRPC3 depletion exerted similar tumor-suppressive functions as SNHG5 knockdown.

CONCLUSION

SNHG5 promoted melanoma development by inhibiting miR-26a-5p and facilitating TRPC3 expression, highlighting the potential of SNHG5 as a novel target therapy for melanoma.

The potential of BRAF-associated non-coding RNA as a therapeutic target in melanoma

INTRODUCTION

The advent of targeted therapies and immune checkpoints inhibitors has enhanced the treatment of metastatic melanomas. Despite striking improvements of patients' survival, drug resistance continues to limit the efficacy of such treatments. Genetic and nongenetic/adaptive mechanisms of resistance could be involved; in the latter mechanism, noncoding RNAs (ncRNAs) are emerging as key players. Areas covered: This article outlines the current knowledge of ncRNA involvement in BRAF-mutant melanomas and the development of resistance to targeted/immunotherapies. We also discuss how ncRNAs can be exploited for the development of therapeutic and diagnostic approaches. Expert opinion: ncRNAs can be envisaged as powerful diagnostics and therapeutics. Despite progress in our knowledge about their deregulation in cancer, it is still difficult to derive universal and robust ncRNAs unique signatures of malignancy for diagnostic purposes, which need validation in large cohort of patients. Also, ncRNA specific targeting to melanoma cells in vivo requires the development of improved systemic delivery tools. In this regard, the development of stable nanodelivery particles seems to offer renewed hope for success in the clinic.

LINC01585 functions as a regulator of gene expression by the CAMP/CREB signaling pathway in breast cancer

OBJECTIVE

Breast cancer is the leading cause of cancer death among women. Nowadays, long non-coding RNAs (lncRNAs) have been identified and emerged as critical bio-markers in breast cancer tumorigenesis and progression. However, only a handful of lncRNAs which are implicated in BC have been characterized. The underlying molecular mechanisms are still largely unknown.

METHODS

In this study, we explored 12 nominated lncRNAs at breast cancer susceptibility loci identified by genome-wide association studies to contribute to the risk and effects of breast cancer. We then analyzed these lncRNAs in a total of 132 pairs of breast cancer tissues and surrounding non-tumor tissues from southern China population.

RESULTS

Here, we report a novel lncRNA, LINC01585, is aberrantly down regulated during breast cancer (BC). Next, to explore the molecular mechanisms underlying the biological activity of LINC01585, we identified LINC01585 binding protein by RNA pull-down experiments. Functionally, we found that LINC01585 overexpression inhibited breast cancer proliferation and growth by prototypical experiments. Mechanistically, LINC01585 was located in nuclear and binding with NONO protein. Interestingly, when LINC01585 was down-expressed, NONO separated from LINC01585 and then interacted with CRTC. The complex promotes CAMP/CREB target gene transcription and thus promotes the growth of breast cancer.

CONCLUSIONS

A series of discoveries suggest to us that LINC01585 has a potential value in anti-carcinoma therapy and deserves further investigation.

lncRNA-ATB functions as a competing endogenous RNA to promote YAP1 by sponging miR-590-5p in malignant melanoma

The critical long non‑coding RNAs (lncRNAs) involved in the carcinogenesis and progression of malignant melanoma (MM) have not been fully investigated. In the present study, it was identified that lncRNA activated by transforming growth factor‑β (lncRNA‑ATB) was upregulated in MM tissues and cells compared with benign nevus cells and human melanocytes, via comparative lncRNA screening from Gene Expression Omnibus datasets and reverse transcription‑quantitative polymerase chain reaction analysis. Furthermore, lncRNA‑ATB promoted the cell proliferation, cell migration, and cell invasion of MM cells in vitro, and tumor growth in vivo. It was additionally identified that lncRNA‑ATB attenuated cell cycle arrest and inhibited cellular apoptosis in MM cells. Finally, it was demonstrated that lncRNA‑ATB functions as a competing endogenous RNA (ceRNA) to enhance Yes associated protein 1 expression by competitively sponging microRNA miR‑590‑5p in MM cells. In conclusion, the present study revealed the expression and roles of lncRNA‑ATB in MM, and indicated that lncRNA‑ATB functions as a ceRNA to promote MM proliferation and invasion by sponging miR‑590‑5p.

HOXA10‑AS: A novel oncogenic long non‑coding RNA in glioma

Glioma is the most common primary malignant tumor of the central nervous system. Emerging evidence has demonstrated that long non‑coding RNAs (lncRNAs) serve a major role of regulation in various types of human cancer, including glioma. However, the biological roles of thousands of lncRNAs remain unknown and require further identification. The present study investigated the functional role of lncRNA‑HOXA10‑AS in glioma. The present study examined the expression patterns of HOXA10‑AS in glioma and normal brain tissues, as well as glioma cell lines and normal human astrocytes (HA) via reverse transcription‑quantitative polymerase chain reaction. HOXA10‑AS knockdown cells were generated using lentiviral short hairpin RNA against HOXA10‑AS in A172 and U251 glioma cells. Cell growth was assessed by MTT assay, and a flow cytometer was used to investigate cell proliferation, cell cycle distribution and cell apoptosis. Western blot analysis was performed to analyze the expression levels of apoptosis‑related proteins. HOXA10‑AS was significantly upregulated in glioma tissues and cell lines, and increased HOXA10‑AS expression levels were associated with higher grades of glioma. Knockdown of HOXA10‑AS inhibited glioma cell proliferation and increased cell apoptosis rates compared with the control cells. HOXA10‑AS markedly regulated the expression of the homeobox A10 (HOXA10) gene. Similarly, HOXA10 expression was increased with higher grades of glioma, and silencing of HOXA10 by small interfering RNA suppressed glioma cell proliferation and induced cell apoptosis. The results of the present study demonstrated that HOXA10‑AS promoted cell growth and survival through activation of HOXA10 gene expression in glioma, which may potentially act as a novel biomarker and therapeutic target for clinical assay development.

Integrative Genome-Wide Analysis of Long Noncoding RNAs in Diverse Immune Cell Types of Melanoma Patients

Genome-wide identification and characterization of long noncoding RNAs (lncRNA) in individual immune cell lineages helps us better understand the driving mechanisms behind melanoma and advance personalized patient treatment. To elucidate the transcriptional landscape in diverse immune cell types of peripheral blood cells (PBC) in stage IV melanoma, we used whole transcriptome RNA sequencing to profile lncRNAs in CD4+, CD8+, and CD14+ PBC from 132 patient samples. Our integrative computational approach identified 27,625 expressed lncRNAs, 2,744 of which were novel. Both T cells (i.e., CD4+ and CD8+ PBC) and monocytes (i.e., CD14+ PBC) exhibited differential transcriptional expression profiles between patients with melanoma and healthy subjects. Cis- and trans-level coexpression analysis suggested that lncRNAs are potentially involved in many important immune-related pathways and the programmed cell death receptor 1 checkpoint pathways. We also identified nine gene coexpression modules significantly associated with melanoma status, all of which were significantly enriched for three mRNA translation processes. Age and melanoma traits closely correlated with each other, implying that melanoma contains age-associated immune changes. Our computational prediction analysis suggests that many cis- and trans-regulatory lncRNAs could interact with multiple transcriptional and posttranscriptional regulatory elements in CD4+, CD8+, and CD14+ PBC, respectively. These results provide novel insights into the regulatory mechanisms involving lncRNAs in individual immune cell types in melanoma and can help expedite cell type-specific immunotherapy treatments for such diseases.Significance: These findings elucidate melanoma-associated changes to the noncoding transcriptional landscape of distinct immune cell classes, thus providing cell type-specific guidance to targeted immunotherapy regimens. Cancer Res; 78(15); 4411-23. ©2018 AACR.

Long non-coding RNA TCF7 predicts the progression and facilitates the growth and metastasis of colorectal cancer

Long non-coding RNA (lnc)TCF7 has been reported to promote the self‑renewal of human cancer stem cells, and enhance the aggressiveness of human non‑small cell lung cancer and hepatocellular carcinoma cells. However, the effect of lncTCF7 on colorectal cancer (CRC) tumorigenesis and progression is currently unclear. In the present study, reverse transcription‑quantitative polymerase chain reaction results demonstrated that lncTCF7 expression was higher in CRC tissues compared with adjacent normal tissues and was significantly associated with tumor size, differentiation degree, tumor‑node‑metastasis grade, lymph node metastasis and invasion depth. In addition, lncTCF7 demonstrated a high sensitivity and specificity for diagnosing CRC, as determined by receiver operating characteristic curve analysis. Furthermore, lncTCF7 silencing in SW‑620 and HT29 CRC cell lines inhibited the proliferation, cell cycle, migration and invasion of cells, as determined by Cell Counting Kit‑8 assays, propidium iodide (PI) staining and flow cytometry, wound healing assays and Transwell invasion assays, respectively; however, Annexin V/PI double staining and flow cytometry indicated that lncTCF7 silencing did not significantly affect the apoptosis of CRC cells. These results indicate that lncTCF7 may predict the progression, and promote the growth and metastasis, of CRC, and may therefore be a novel diagnostic marker and therapeutic target for CRC 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.

SNHG5 promotes proliferation and induces apoptosis in melanoma by sponging miR-155

Background: Melanoma is the most common malignancy of skin cancer. Small nucleolar RNA host gene 5 (SNHG5), a long non-coding RNA (lncRNA), has been demonstrated to be abnormally expressed in multiple malignances. However, the roles and molecular mechanisms of SNHG5 in melanoma progression have not been well identified. Methods: RT-qPCR assays were used to detect the expression patterns of SNHG5 and microRNA-155 (miR-155). Cell proliferation was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and colony formation assays. Cell apoptosis rate was measured by flow cytometry via double-staining of fluorescein isothiocyanate (FITC)-labeled annexin V (Annexin V-FITC) and propidium iodide (PI). The interaction between SNHG5 and miR-155 was validated using bioinformatics analysis, subcellular fraction assay, luciferase assay and RNA immunoprecipitation (RIP) assay. A mouse model of melanoma was established to further verify the effect of SNHG5 on tumor growth in vivo. Results: SNHG5 expression was upregulated in melanoma tumor tissues and cell lines. Moreover, higher SNHG5 expression was associated with advanced pathogenic status and poor prognosis. Functional analysis showed that SNHG5 knockdown suppressed proliferation and facilitated apoptosis in melanoma cells. Mechanical exploration revealed that SNHG5 acted as a molecular sponge of miR-155 in melanoma cells. Restoration experiments delineated that miR-155 down-regulation partly abrogated SNHG5-knockdown-mediated anti-proliferation and pro-apoptosis effect in melanoma cells. In vivo assays further demonstrated that SNHG5 depletion hindered tumor growth through up-regulating miR-155 expression. Conclusion: SNHG5 promoted the development of melanoma by sponging miR-155 in vitro and in vivo, implying the important implication of lncRNAs in melanoma progression and providing a potential therapeutic target for melanoma.

Melanoma is the most common malignancy of skin cancer. Small nucleolar RNA host gene 5 (SNHG5), a long non-coding RNA (lncRNA), has been demonstrated to be upregulated in tumor tissues and cells of melanoma.

The Dark Side of the Epitranscriptome: Chemical Modifications in Long Non-Coding RNAs

The broad application of next-generation sequencing technologies in conjunction with improved bioinformatics has helped to illuminate the complexity of the transcriptome, both in terms of quantity and variety. In humans, 70–90% of the genome is transcribed, but only ~2% carries the blueprint for proteins. Hence, there is a huge class of non-translated transcripts, called long non-coding RNAs (lncRNAs), which have received much attention in the past decade. Several studies have shown that lncRNAs are involved in a plethora of cellular signaling pathways and actively regulate gene expression via a broad selection of molecular mechanisms. Only recently, sequencing-based, transcriptome-wide studies have characterized different types of post-transcriptional chemical modifications of RNAs. These modifications have been shown to affect the fate of RNA and further expand the variety of the transcriptome. However, our understanding of their biological function, especially in the context of lncRNAs, is still in its infancy. In this review, we will focus on three epitranscriptomic marks, namely pseudouridine (Ψ), N⁶-methyladenosine (m⁶A) and 5-methylcytosine (m⁵C). We will introduce writers, readers, and erasers of these modifications, and we will present methods for their detection. Finally, we will provide insights into the distribution and function of these chemical modifications in selected, cancer-related lncRNAs.

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.

MicroRNAs as a tool to aid stratification of colorectal cancer patients and to guide therapy

Colorectal cancer is a common type of malignant disease with high rates of morbidity and mortality. Although treatment options have been expanded over the last years, the mainstay of curative treatment remains surgical removal of the tumor-bearing organ. Systemic treatment options include classic cytotoxic drugs as well as some biological agents. Noncoding RNAs are an evolving field in cancer diagnosis, prognosis and possible treatment. Noncoding miRNAs are small molecules with huge impact on gene expression. They have been a substantial part of cancer research for more than a decade. In this review article, the current knowledge of miRNAs and colorectal cancer diagnosis, prognosis and novel or evolving therapeutic concepts are discussed. Examples of how miRNAs might change the management of the disease will be described.