Long non-coding RNA CASC15 promotes melanoma progression by epigenetically regulating PDCD4

Long noncoding RNAs and HPV-related cervical cancer: Uncovering molecular mechanisms and clinical applications

Cervical cancer (CC) is the primary cause of cancer-related mortality among women in developing countries and is the most prevalent disease linked to human papillomavirus (HPV). Over 70 % of CC cases result from persistent infections with high-risk HPV types. The virus typically targets the mucocutaneous epithelium, generating viral particles in mature epithelial cells, which leads to disruptions in normal cell-cycle regulation and promotes uncontrolled cellular proliferation. This unchecked cell division results in the accumulation of genetic damage, contributing to the pathogenesis of CC. While HPV infection is a key etiological factor, the disease's progression also necessitates the involvement of genetic and epigenetic influences. One of the epigenetic regulators, long noncoding RNAs (lncRNAs), are characterized by transcripts exceeding 200 nucleotides. These molecules play crucial roles in various cellular processes, including transcription regulation, RNA metaboli35 per 100,000sm, and apoptosis. Investigating the specific roles of lncRNAs in modulating gene expression related to the oncogenic mechanisms of CC, particularly in the context of high-risk HPV infections, may provide valuable insights for diagnostic and therapeutic advancements. Herein, we first review key molecular mechanisms by which lncRNAs interfere with CC-related HPV development. Then, diagnostic, prognostic, and therapeutic potentials of these lncRNA molecules will be highlighted in depth. The focus of this article is on the role of lncRNAs associated with HPV-related CC, emphasizing the investigation of signaling pathways and their underlying molecular mechanisms. Furthermore, we explore the therapeutic potential and diagnostic relevance of the most significant lncRNAs in the context of CC, thereby highlighting their importance in advancing treatment strategies and improving patient outcomes.

Unravelling the Regulatory Roles of lncRNAs in Melanoma: From Mechanistic Insights to Target Selection

Melanoma is the deadliest form of skin cancer, and its treatment poses significant challenges due to its aggressive nature and resistance to conventional therapies. Long non-coding RNAs (lncRNAs) represent a new frontier in the search for suitable targets to control melanoma progression and invasiveness. Indeed, lncRNAs exploit a wide range of regulatory functions along chromatin remodeling, gene transcription, post-transcription, transduction, and post-transduction to ultimately tune multiple cellular processes. The understanding of this intricate and flexible regulatory network orchestrated by lncRNAs in pathological conditions can strategically support the rational identification of promising targets, ultimately speeding up the setup of new therapeutics to integrate the currently available approaches. Here, the most recent findings on lncRNAs involved in melanoma will be analyzed. In particular, the functional links between their mechanisms of action and some frequently underestimated features, like their different subcellular localizations, will be highlighted.

YY1-induced lncRNA00511 promotes melanoma progression via the miR-150-5p/ADAM19 axis

Increasing evidence indicates that long noncoding RNAs (lncRNAs) are therapeutic targets and key regulators of tumors development and progression, including melanoma. Long intergenic non-protein-coding RNA 511 (LINC00511) has been demonstrated as an oncogenic molecule in breast, stomach, colorectal, and lung cancers. However, the precise role and functional mechanisms of LINC00511 in melanoma remain unknown. This study confirmed that LINC00511 was highly expressed in melanoma cells (A375 and SK-Mel-28 cells) and tissues, knockdown of LINC00511 could inhibit melanoma cell migration and invasion, as well as the growth of subcutaneous tumor xenografts in vivo. By using Chromatin immunoprecipitation (ChIP) assay, it was demonstrated that the transcription factor Yin Yang 1 (YY1) is capable of binding to the LINC00511 promoter and enhancing its expression in cis. Further mechanistic investigation showed that LINC00511 was mainly enriched in the cytoplasm of melanoma cells and interacted directly with microRNA-150-5p (miR-150-5p). Consistently, the knockdown of miR-150-5p could recover the effects of LINC00511 knockdown on melanoma cells. Furthermore, ADAM metallopeptidase domain expression 19 (ADAM19) was identified as a downstream target of miR-150-5p, and overexpression of ADAM19 could promote melanoma cell proliferation. Rescue assays indicated that LINC00511 acted as a competing endogenous RNA (ceRNA) to sponge miR-150-5p and increase the expression of ADAM19, thereby activating the PI3K/AKT pathway. In summary, we identified LINC00511 as an oncogenic lncRNA in melanoma and defined the LINC00511/miR-150-5p/ADAM19 axis, which might be considered a potential therapeutic target and novel molecular mechanism the treatment of patients with melanoma.

Programmed cell death 4: A novel player in the pathogenesis of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a pathological condition recognized by menstrual cycle irregularities, androgen excess, and polycystic ovarian morphology, affecting a significant proportion of women of childbearing age and accounting for the most prevalent cause of anovulatory sterility. In addition, PCOS is frequently accompanied by metabolic and endocrine disturbances such as obesity, dyslipidemia, insulin resistance, and hyperinsulinemia, indicating the multiplicity of mechanisms implicated in the progression of PCOS. However, the exact pathogenesis of PCOS is yet to be elucidated. Programmed cell death 4 (PDCD4) is a ubiquitously expressed protein that contributes to the regulation of various cellular processes, including gene expression, cell cycle progression, proliferation, and apoptosis. Despite some disparities concerning its exact cellular effects, PDCD4 is generally characterized as a protein that inhibits cell cycle progression and proliferation and instead drives the cell into apoptosis. The apoptosis of granulosa cells (GCs) is speculated to take a major part in the occurrence and progression of PCOS by ceasing antral follicle development and compromising oocyte competence. Given the possible involvement of GC apoptosis in the progression of PCOS, as well as the contribution of PDCD4 to the regulation of cell apoptosis and the development of metabolic diseases, the current review aimed to discuss whether or how PDCD4 can play a role in the pathogenesis of PCOS by affecting GC apoptosis.

lncRNAs-EZH2 interaction as promising therapeutic target in cutaneous melanoma

Melanoma is the most lethal skin cancer with increasing incidence worldwide. Despite a great improvement of diagnostics and treatment of melanoma patients, this disease is still a serious clinical problem. Therefore, novel druggable targets are in focus of research. EZH2 is a component of the PRC2 protein complex that mediates epigenetic silencing of target genes. Several mutations activating EZH2 have been identified in melanoma, which contributes to aberrant gene silencing during tumor progression. Emerging evidence indicates that long non-coding RNAs (lncRNAs) are molecular "address codes" for EZH2 silencing specificity, and targeting lncRNAs-EZH2 interaction may slow down the progression of many solid cancers, including melanoma. This review summarizes current knowledge regarding the involvement of lncRNAs in EZH2-mediated gene silencing in melanoma. The possibility of blocking lncRNAs-EZH2 interaction in melanoma as a novel therapeutic option and plausible controversies and drawbacks of this approach are also briefly discussed.

A study of the prognostic value of long non-coding RNA CASC15 in human solid tumors utilizing The Cancer Genome Atlas (TCGA) datasets and a meta-analysis

BACKGROUND AND AIMS

Several malignant solid tumors have been reported to have an abnormal expression of the long non-coding RNA CASC15 (lncRNA CASC15). However, the clinicopathologic and prognostic importance of CASC15 in solid tumors are unknown. As a result, we examined the interrelationship between CASC15, overall survival length, and clinicopathological attributes of cancers affecting humans by analyzing various studies and The Cancer Genome Atlas (TCGA) data related to CASC15 expression.

METHODS

Web of Science, PubMed, Cochrane Library, Embase, Chinese WanFang, and Chinese CNKI databases were used to conduct a literature search. Hazard ratios (HRs) and Pooled odds ratios (ORs) were calculated taking 95% confidence intervals (CIs). The results of the current meta-analysis were further validated using TCGA datasets.

RESULTS

A total of 12 eligible studies enrolling 767 patients were included in this meta-analysis. Findings of the analysis showed that CASC15 expression had a significant relation to the metastasis of lymph node (OR = 3.30, 95%CI = 1.88-5.81, p < 0.001), distant metastasis (OR = 2.64, 95%CI = 1.24-5.63, p = 0.012), and high TNM/clinical stage (OR = 2.67, 95%CI = 1.34-5.32, p = 0.005). Additionally, we found that a poor outcome for overall survival (OS) was predicted by an elevation in CASC15 expression (HR = 2.01, 95%CI = 1.71-2.36, p < 0.001). Further investigation of the TCGA dataset revealed that CASC15 had abnormal expression in many cancers, which at least partially validated the findings of the current meta-analysis.

CONCLUSIONS

According to the latest meta-analysis and systematic review, high expression levels of CASC15 are associated with poor survival outcomes for solid tumor patients, and the use of CASC15 as a solid tumor prognostic predictor has a solid theoretical foundation.

Identification of endoplasmic reticulum stress-related lncRNAs in lung adenocarcinoma by bioinformatics and experimental validation

BACKGROUND

Endoplasmic reticulum stress (ERs) is an important cellular self-defence mechanism, which is closely related to tumorigenesis and development. However, the role of endoplasmic reticulum stress state in the development of lung adenocarcinoma (LUAD) has not been clarified.

METHODS

The lncRNAs associated with endoplasmic reticulum stress were identified by co-expression analysis in public databases, and by the least absolute shrinkage and selection operator (LASSO) regression and multivariate Cox regression modelling, we constructed a prognostic model based on endoplasmic reticulum stress-related lncRNAs (ERs-related lncRNAs), performed immune analysis, TME, TMB and clinical drug prediction for model-related risk scores, and performed correlation validation in public databases and at the human tissue level.

RESULTS

Five ERs-related lncRNAs were used to construct an ERs-related lncRNA signature (ERs-related LncSig), which can predict the prognosis of LUAD. Patients in the high-risk group had worse survival, and differences existed in immune cell infiltration, immune function, immune checkpoint analysis, tumour microenvironment (TME), tumour mutational burden (TMB), immunotherapy efficacy, and sensitivity to some commonly used chemotherapeutic agents between high and low risk groups.

CONCLUSION

Our study demonstrated that ERs-related lncRNA signature can be used for the prognostic evaluation of LUAD patients and may provide new insights into clinical decision-making and personalised medicine for LUAD.

Long non-coding RNAs and melanoma: From diagnosis to therapy

Although extremely rare, malignant melanoma is the deadliest type of skin malignancy with the inherent capability to invade other organs and metastasize to distant tissues. In 2021, it was estimated that approximately 106,110 patients may have received the diagnosis of melanoma, with a mortality rate of 7180. Surgery remains the common choice for treatment in patients with melanoma. Despite many advances in the treatment of melanoma, some patients, such as those who have received cytotoxic chemotherapeutic and immunotherapic agents, a significant number of patients may show inadequate treatment response following initiating these treatments. Non-coding RNAs, including lncRNAs, have become recently popular and attracted the attention of many researchers to make new insights into the pathogenesis of many diseases, particularly malignancies. LncRNAs have been thoroughly investigated in multiple cancers such as melanoma and have been shown to play a major role in regulating various physiological and pathological cellular processes. Considering their core regulatory function, these non-coding RNAs may be appropriate candidates for melanoma patients' diagnosis, prognosis, and treatment. In this review, we will cover all the current literature available for lncRNAs in melanoma and will discuss their potential benefits as diagnostic and/or prognostic markers or potent therapeutic targets in the treatment of melanoma patients.

Long Non-Coding RNAs: Tools for Understanding and Targeting Cancer Pathways

The regulatory nature of long non-coding RNAs (lncRNAs) has been well established in various processes of cellular growth, development, and differentiation. Therefore, it is vital to examine their contribution to cancer development. There are ample examples of lncRNAs whose cellular levels are significantly associated with clinical outcomes. However, whether these non-coding molecules can work as either key drivers or barriers to cancer development remains unknown. The current review aims to discuss some well-characterised lncRNAs in the process of oncogenesis and extrapolate the extent of their decisive contribution to tumour development. We ask if these lncRNAs can independently initiate neoplastic lesions or they always need the modulation of well characterized oncogenes or tumour suppressors to exert their functional properties. Finally, we discuss the emerging genetic approaches and appropriate animal and humanised models that can significantly contribute to the functional dissection of lncRNAs in cancer development and progression.

Regulation of LncRNAs in Melanoma and Their Functional Roles in the Metastatic Process

Long non-coding RNAs (lncRNAs) are key regulators of numerous intracellular processes leading to tumorigenesis. They are frequently deregulated in cancer, functioning as oncogenes or tumor suppressors. As they act through multiple mechanisms, it is not surprising that they may exert dual functions in the same tumor. In melanoma, a highly invasive and metastatic tumor with the propensity to rapidly develop drug resistance, lncRNAs play different roles in: (i) guiding the phenotype switch and leading to metastasis formation; (ii) predicting the response of melanoma patients to immunotherapy; (iii) triggering adaptive responses to therapy and acquisition of drug resistance phenotypes. In this review we summarize the most recent findings on the lncRNAs involved in melanoma growth and spreading to distant sites, focusing on their role as biomarkers for disease diagnosis and patient prognosis, or targets for novel therapeutic approaches.

Whole-genome-scale identification of novel non-protein-coding RNAs controlling cell proliferation and survival through a functional forward genetics strategy

Identification of cell fate-controlling lncRNAs is essential to our understanding of molecular cell biology. Here we present a human genome-scale forward-genetics approach for the identification of lncRNAs based on gene function. This approach can identify genes that play a causal role, and immediately distinguish them from those that are differentially expressed but do not affect cell function. Our genome-scale library plus next-generation-sequencing and bioinformatic approach, radically upscales the breadth and rate of functional ncRNA discovery. Human gDNA was digested to produce a lentiviral expression library containing inserts in both sense and anti-sense orientation. The library was used to transduce human Jurkat T-leukaemic cells. Cell populations were selected using continuous culture ± anti-FAS IgM, and sequencing used to identify sequences controlling cell proliferation. This strategy resulted in the identification of thousands of new sequences based solely on their function including many ncRNAs previously identified as being able to modulate cell survival or to act as key cancer regulators such as AC084816.1*, AC097103.2, AC087473.1, CASC15*, DLEU1*, ENTPD1-AS1*, HULC*, MIRLET7BHG*, PCAT-1, SChLAP1, and TP53TG1. Independent validation confirmed 4 out of 5 sequences that were identified by this strategy, conferred a striking resistance to anti-FAS IgM-induced apoptosis.

Genetic and Genomic Pathways of Melanoma Development, Invasion and Metastasis

Melanoma is a serious form of skin cancer that accounts for 80% of skin cancer deaths. Recent studies have suggested that melanoma invasiveness is attributed to phenotype switching, which is a reversible type of cell behaviour with similarities to epithelial to mesenchymal transition. Phenotype switching in melanoma is reported to be independent of genetic alterations, whereas changes in gene transcription, and epigenetic alterations have been associated with invasiveness in melanoma cell lines. Here, we review mutational, transcriptional, and epigenomic alterations that contribute to tumour heterogeneity in melanoma, and their potential to drive melanoma invasion and metastasis. We also discuss three models that are hypothesized to contribute towards aspects of tumour heterogeneity and tumour progression in melanoma, namely the clonal evolution model, the cancer stem cell model, and the phenotype switching model. We discuss the merits and disadvantages of each model in explaining tumour heterogeneity in melanoma, as a precursor to invasion and metastasis.

The Functional Role of Long Non-Coding RNAs in Melanoma

Melanoma is the most lethal skin cancer, with increasing incidence worldwide. The molecular events that drive melanoma development and progression have been extensively studied, resulting in significant improvements in diagnostics and therapeutic approaches. However, a high drug resistance to targeted therapies and adverse effects of immunotherapies are still a major challenge in melanoma treatment. Therefore, the elucidation of molecular mechanisms of melanomagenesis and cancer response to treatment is of great importance. Recently, many studies have revealed the close association of long noncoding RNAs (lncRNAs) with the development of many cancers, including melanoma. These RNA molecules are able to regulate a plethora of crucial cellular processes including proliferation, differentiation, migration, invasion and apoptosis through diverse mechanisms, and even slight dysregulation of their expression may lead to tumorigenesis. lncRNAs are able to bind to protein complexes, DNA and RNAs, affecting their stability, activity, and localization. They can also regulate gene expression in the nucleus. Several functions of lncRNAs are context-dependent. This review summarizes current knowledge regarding the involvement of lncRNAs in melanoma. Their possible role as prognostic markers of melanoma response to treatment and in resistance to therapy is also discussed.

Pathogenic roles of long noncoding RNAs in melanoma: Implications in diagnosis and therapies

Melanoma is one of the most dangerous types of cutaneous neoplasms, which are pigment-producing cells of neuroectodermal origin found all over the body. A great deal of research is focused on the mechanisms of melanoma to promote better diagnostic and treatment options for melanoma in its advanced stages. The progression of melanoma involves alteration in different levels of gene expression. With the successful implementation of next-generation sequencing technology, an increasing number of long noncoding RNAs (lncRNAs) sequences have been discovered, and a significant number of them have phenotypic effects in both in vitro and in vivo studies, implying that they play an important role in the occurrence and progression of human cancers, particularly melanoma. A number of evidence indicated that lncRNAs are important regulators in tumor cell proliferation, invasion, apoptosis, immune escape, energy metabolism, drug resistance, epigenetic regulation. To better understand the role of lncRNAs in melanoma tumorigenesis, we categorize melanoma-associated lncRNAs according to their cellular functions and associations with gene expression and signaling pathways in this review. Based on the mechanisms of lncRNA, we discuss the possibility of lncRNA-target treatments, and the application of liquid biopsies to detect lncRNAs in melanoma diagnosis and prognosis.

STAT3-induced ZBED3-AS1 promotes the malignant phenotypes of melanoma cells by activating PI3K/AKT signaling pathway

Melanoma is considered as the most frequent primary malignancy occurring in skin. Accumulating studies have suggested that long non-coding RNAs (lncRNAs) play critical parts in multiple cancers. In this study, we explored the molecular mechanism of ZBED3 antisense RNA 1 (ZBED3-AS1) in melanoma. We observed that ZBED3-AS1 expression was remarkably up-regulated in melanoma tissues, and high ZBED3-AS1 level was linked to unsatisfactory survival of melanoma patients. Then, we discovered that ZBED3-AS1 was overexpressed in melanoma cells compared with human epidermal melanocytes. In addition, loss-of-function assays verified that ZBED3-AS1 knockdown restrained cell proliferation, migration, epithelial-mesenchymal transition (EMT), and stemness in melanoma. In addition, signal transducer and activator of transcription 3 (STAT3), which also showed tumour-facilitating functions in melanoma, was confirmed as a transcriptional activator of ZBED3-AS1. Moreover, ZBED3-AS1 enhanced the expression of AT-rich interaction domain 4B (ARID4B) through sequestering miR-381-3p. Importantly, we further confirmed that ZBED3-AS1 promoted the malignant progression of melanoma by regulating miR-381-3p/ARID4B axis to activate the phosphatidylinositol 3-kinase/AKT serine/threonine kinase (PI3K/AKT) signalling pathway. In a word, our research might provide a novel therapeutic target for melanoma.

CASC15: A Tumor-Associated Long Non-Coding RNA

BACKGROUND

CASC15, one of long non-coding RNA, is involved in the regulation of many tumor biological processes, and is expected to become a new biological therapeutic target. This paper aims to elucidate the pathophysiological function of CASC15 in various tumors.

METHODS

The relationship between CASC15 and tumors was analyzed by searching references, and summarized the specific pathophysiological mechanism of CASC15.

RESULTS

LncRNA CASC15 is closely related to tumor development, and has been shown to be abnormally high expressed in all kinds of tumors, including breast cancer, cervical cancer, lung cancer, hepatocellular carcinoma, gastric cancer, bladder cancer, colon cancer, colorectal cancer, cardiac hypertrophy, intrahepatic cholangiocarcinoma, leukemia, melanoma, tongue squamous cell carcinoma and nasopharyngeal carcinoma. However, CASC15 has been found to be down-expressed abnormally in ovarian cancer, glioma and neuroblastoma. Besides, it is identified that CASC15 can affect the proliferation, invasion and apoptosis of tumors.

CONCLUSION

LncRNA CASC15 has the potential to become a new therapeutic target or marker for a variety of tumors.

MicroRNA-183-5p contributes to malignant progression through targeting PDCD4 in human hepatocellular carcinoma

Hepatocellular carcinoma (HCC) remains one of the most common malignant tumors worldwide. The present study aimed to investigate the biological role of microRNA-183-5p (miR-183-5p), a novel tumor-related microRNA (miRNA), in HCC and illuminate the possible molecular mechanisms. The expression patterns of miR-183-5p in clinical samples were characterized using qPCR analysis. Kaplan–Meier survival curve was applied to evaluate the correlation between miR-183-5p expression and overall survival of HCC patients. Effects of miR-183-5p knockdown on HCC cell proliferation, apoptosis, migration and invasion capabilities were determined via Cell Counting Kit-8 (CCK8) assays, flow cytometry, scratch wound healing assays and Transwell invasion assays, respectively. Mouse neoplasm transplantation models were established to assess the effects of miR-183-5p knockdown on tumor growth in vivo. Bioinformatics analysis, dual-luciferase reporter assays and rescue assays were performed for mechanistic researches. Results showed that miR-183-5p was highly expressed in tumorous tissues compared with adjacent normal tissues. Elevated miR-183-5p expression correlated with shorter overall survival of HCC patients. Moreover, miR-183-5p knockdown significantly suppressed proliferation, survival, migration and invasion of HCC cells compared with negative control treatment. Consistently, miR-183-5p knockdown restrained tumor growth in vivo. Furthermore, programmed cell death factor 4 (PDCD4) was identified as a direct target of miR-183-5p. Additionally, PDCD4 down-regulation was observed to abrogate the inhibitory effects of miR-183-5p knockdown on malignant phenotypes of HCC cells. Collectively, our data suggest that miR-183-5p may exert an oncogenic role in HCC through directly targeting PDCD4. The current study may offer some new insights into understanding the role of miR-183-5p in HCC.

Circ_0003266 sponges miR-503-5p to suppress colorectal cancer progression via regulating PDCD4 expression

BACKGROUND

Circular RNAs (circRNAs) feature prominently in tumor progression. However, the biological function and molecular mechanism of circ_0003266 in colorectal cancer (CRC) require further investigation.

METHODS

Circ_0003266 expression in 46 pairs CRC tissues / adjacent tissues, and CRC cell lines was detected by quantitative real-time polymerase chain reaction (qRT-PCR); after circ_0003266 was overexpressed or knocked down in CRC cells, cell proliferation, apoptosis, migration, and invasion were evaluated by the cell counting kit-8 (CCK-8), flow cytometry, and Transwell assays, respectively; the interaction among circ_0003266, miR-503-5p, and programmed cell death 4 (PDCD4) was confirmed using bioinformatics analysis and dual-luciferase reporter assay; PDCD4 protein expression in CRC cells was quantified using Western blot.

RESULTS

Circ_0003266 was significantly lowly expressed in CRC tissues and cell lines. Circ_0003266 overexpression markedly repressed CRC cell proliferation, migration, and invasion, and accelerated the cell apoptosis, but its overexpression promoted the malignant phenotypes of CRC cells. PDCD4 was a direct target of miR-503-5p and circ_0003266 promoted PDCD4 expression by competitively sponging miR-503-5p.

CONCLUSION

Circ_0003266 suppresses the CRC progression via sponging miR-503-5p and regulating PDCD4 expressions, which suggests that circ_0003266 may serve as a novel target for the treatment of CRC.

Clinical Significance of PDCD4 in Melanoma by Subcellular Expression and in Tumor-Associated Immune Cells

Simple Summary

While targeting programmed cell death (PDCD) 1 is a central treatment against melanoma, little is known about the related protein PDCD4. We defined differences in melanoma PDCD4 subcellular localization (either total cellular or nuclear-only) during oncogenesis, evaluated its presence on tumor-infiltrating immune cells, and determined its impact on survival. High PDCD4 expression resulted in improved survival in patients with primary and intracranial but not extracranial metastatic melanoma. High PDCD4 levels in surrounding tumor tissue were also associated with increased infiltrating immune cells. PDCD4 may be a potentially useful biomarker in melanoma to help guide our understanding of patient prognosis. Methods to increase PDCD4 in those with melanoma brain metastases may also help improve disease response.

Abstract

Little is known about the subcellular localization and function of programmed cell death 4 (PDCD4) in melanoma. Our past studies suggest PDCD4 interacts with Pleckstrin Homology Domain Containing A5 (PLEKHA5) to influence melanoma brain metastasis outcomes, as high intracranial PDCD4 expression leads to improved survival. We aimed to define the subcellular distribution of PDCD4 in melanoma and in the tumor microenvironment during neoplastic progression and its impact on clinical outcomes. We analyzed multiple tissue microarrays with well-annotated clinicopathological variables using quantitative immunofluorescence and evaluated single-cell RNA-sequencing on a brain metastasis sample to characterize PDCD4+ immune cell subsets. We demonstrate differences in PDCD4 expression during neoplastic progression, with high tumor and stromal PDCD4 levels associated with improved survival in primary melanomas and in intracranial metastases, but not in extracranial metastatic disease. While the expression of PDCD4 is well-documented on CD8+ T cells and natural killer cells, we show that it is also found on B cells and mast cells. PDCD4 expression in the tumor microenvironment is associated with increased immune cell infiltration. Further studies are needed to define the interaction of PDCD4 and PLEKHA5 and to evaluate the utility of this pathway as a therapeutic target in melanoma brain metastasis.

Functional Prediction of Long Noncoding RNAs in Cutaneous Melanoma Using a Systems Biology Approach

Cutaneous melanoma is the most aggressive type of skin cancer which its incidence has significantly increased in recent years worldwide. Thus, more investigations are required to identify the underlying mechanisms of melanoma malignant transformation and metastasis. In this context, long noncoding RNAs (lncRNAs) are a new type of noncoding transcripts that their dysregulations are associated with almost all cancers including melanoma. However, the precise functional roles of most of the significantly altered lncRNAs in melanoma have not yet been fully inspected. In this study, a comprehensive list of lncRNAs was interrogated across cutaneous melanoma samples to identify the significantly altered/dysregulated lncRNAs. To this end, lncRNAs were filtered in several steps and the selected lncRNAs projected to a bioinformatic and systems biology analysis using several publicly available databases and tools such as GEPIA and cBioPortal. According to our results, 30 lncRNAs were notably altered/dysregulated in cutaneous melanoma most of which were co-expressed with each other. Also, co-expression/alteration and differential expression analyses led to the selection of 12 out of these 30 lncRNAs as cutaneous melanoma key lncRNAs. Furthermore, functional demonstrated that these 12 lncRNAs might be involved in melanoma-relevant biological processes and pathways. In addition, the end result of our analyses demonstrated that these lncRNAs are associated with the clinicopathological features of melanoma patients. These 12 lncRNAs need to be further investigated in future studies to characterize their exact roles in melanoma development and to identify their potential for being used as drug targets and/or biomarkers for cutaneous melanoma.

Identification of a ten-long noncoding RNA signature for predicting the survival and immune status of patients with bladder urothelial carcinoma based on the GEO database: a superior machine learning model

Bladder urothelial carcinoma (BLCA) is recognized to be immunogenic and tumorigenic. This study identified a novel long noncoding RNA (lncRNA) signature for predicting survival for patients with BLCA. A univariate Cox regression model and the random survival forest-variable hunting (RSF-VH) algorithm were employed to achieve variable selection. Ten lncRNAs (LOC105375787, CYTOR, URB1-AS1, C21orf91-OT1, CASC15, LOC101928433, FLJ45139, LINC00960, HOTAIR and TTTY19) with the highest prognostic values were identified to establish the prognostic model. The nomogram integrating the signature and clinical factors showed high concordance index values of 0.94, 0.7 and 0.90 in the three datasets, and the calibration curves showed concordance between the predicted and observed 3- and 5-year survival rates. The risk score based on the 10-lncRNA signature accurately distinguished high- and low-risk BLCA patients with different disease-specific survival(DSS) or overall survival(OS) outcomes, which were stratified according to clinical factors, including T stage and tumour grade. Gene set enrichment analysis identified BLCA-specific biological pathways and enriched functional categories, such as the cell cycle, DNA repair and immune system. Furthermore, the increased infiltration of immune cells in the high-risk group indicated that lncRNA-related inflammation may reduce the survival of BLCA patients.

The dual functions of the long noncoding RNA CASC15 in malignancy

Emerging evidence has demonstrated that long noncoding RNAs (lncRNAs) play vital roles in tumorigenesis and progression. LncRNAs can participate in various biological processes, such as cell growth, anti-apoptosis functions, migration, and invasion. Cancer susceptibility candidate 15 (CASC15) is a cancer-related lncRNA that has been reported to play opposite roles in the pathogenesis of different types of cancers. Studies have shown that CASC15 is downregulated in ovarian cancer and neuroblastoma, acting mainly as a tumour suppressor, while it is highly expressed and carcinogenic in hepatocellular carcinoma (HCC), lung cancer, tongue squamous cell carcinoma, gastric cancer, colorectal cancer, cervical cancer, and breast cancer. Furthermore, aberrant CASC15 expression is associated with tumorigenesis, progression, and patient outcomes via regulation of target genes and signalling pathways. In this review, we summarize current data concerning the regulatory functions and underlying mechanisms of CASC15 in tumour development. We also highlight its potential clinical utility as a biomarker for early detection or as a therapeutic target in human cancers.

Comprehensive Review on the Clinical Relevance of Long Non-Coding RNAs in Cutaneous Melanoma

Cutaneous melanoma is considered a rare tumor, although it is one of the most common cancers in young adults and its incidence has risen in the last decades. Targeted therapy, with BRAF and MEK inhibitors, and immunotherapy revolutionized the treatment of metastatic melanoma but there is still a considerable percentage of patients with primary or acquired resistance to these therapies. Recently, oncology researchers directed their attention at the role of long non-coding RNAs (lncRNAs) in different types of cancers, including melanoma. lncRNAs are RNA transcripts, initially considered "junk sequences", that have been proven to have a crucial role in the fine regulation of physiological and pathological processes of different tissues. Furthermore, they are more expressed in tumors than protein-coding genes, constituting perfect candidates either as biomarkers (diagnostic, prognostic, predictive) or as therapeutic targets. In this work, we reviewed all the literature available for lncRNA in melanoma, elucidating all the potential roles in this tumor.

CASC15 Polymorphisms are Correlated With Breast Cancer Susceptibility in Chinese Han Women

INTRODUCTION

Breast cancer (BC) is a prevalent malignant tumor among women. Numerous studies have been reported that long noncoding RNAs (lncRNAs) were associated with various human diseases.

MATERIALS AND METHODS

In the current study, 681 patients with BC and 680 unrelated controls were recruited to investigate the correlation between lncRNA cancer susceptibility candidate 15 (CASC15) polymorphisms and BC risk in Chinese Han women. We performed single-nucleotide polymorphism genotyping using the Agena MassARRAY platform. The relationship between lncRNA CASC15 polymorphisms and the risk of BC were evaluated through odds ratios and 95% confidence intervals.

RESULTS

Our results suggested that the lncRNA CASC15 rs7740084 "G/G" genotype and rs1928168 "T/C" genotype significantly reduced BC risk in different genetic models (P = .045, P = .029, and P = .047, respectively). However, rs9393266 "C/T" and "C/T-T/T" genotypes were correlated with the risk of BC (P = .021 and P = .048). In addition, we also observed that rs1928168 was related to the risk of BC in patients with age > 50 years (P = .025), body mass index > 24 (P = .006), and tumor size (P = .035). For rs9393266, it was revealed that the "C/T" and "C/T-T/T" genotypes were related to BC risk in people with age ≤ 50 years (P = .005) and body mass index > 24 (P = .023).

CONCLUSION

In summary, our results revealed a potential interaction between lncRNA CASC15 polymorphisms and BC susceptibility. The results provided an important insight into lncRNA CASC15 function in the development of BC.

Regulation of melanoma malignancy by the RP11-705C15.3/miR-145-5p/NRAS/MAPK signaling axis

Melanoma is a common lethal skin cancer. Dissecting molecular mechanisms driving the malignancy of melanoma may uncover potential therapeutic targets. We previously identified miR-145-5p as an important tumor-suppressive microRNA in melanoma. Here, we further investigated the roles of long non-coding RNAs (lncRNAs) in melanoma. We identified RP11-705C15.3, a regulator of miR-145-5p, as an oncogenic lncRNA in melanoma. RP11-705C15.3 competitively bound miR-145-5p, relieved the repressive roles of miR-145-5p on its target NRAS, upregulated NRAS expression, and activated MAPK signaling. In vitro functional assays revealed that ectopic expression of RP11-705C15.3 promoted melanoma cell proliferation, inhibited apoptosis, and promoted migration and invasion. Silencing of RP11-705C15.3 repressed melanoma cell proliferation, induced apoptosis, and repressed migration and invasion. Notably, the roles of RP11-705C15.3 in melanoma cell proliferation, apoptosis, migration and invasion are reversed by miR-145-5p overexpression. In vivo functional assays revealed that RP11-705C15.3 promoted melanoma tumor growth and metastasis, which were also reversed by miR-145-5p overexpression. Furthermore, we investigated the expression of RP11-705C15.3 in clinical melanoma tissues and found that RP11-705C15.3 was increased in melanoma tissues. High expression of RP11-705C15.3 was positively correlated with thickness, ulceration, metastasis, and inferior overall survival. Taken together, our findings suggest RP11-705C15.3 as a novel oncogene in melanoma, and highlight that the RP11-705C15.3/miR-145-5p/NRAS/MAPK signaling axis may be potential therapeutic targets for melanoma.

LncRNA CASC15 is Upregulated in Osteosarcoma Plasma Exosomes and CASC15 Knockdown Inhibits Osteosarcoma Progression by Regulating miR-338-3p/RAB14 Axis

Background

Currently, plenty of studies have demonstrated that lncRNAs can act as crucial roles during the progression of various tumors, including osteosarcoma (OS), and emerging evidences indicated that lncRNAs are abundant and stable in exosomes. The objective of this study is to reveal the dysregulated lncRNAs in OS plasma exosomes and explore their functions in OS.

Materials and Methods

Microarray was performed to analyze dysregulated exosomal lncRNAs. Western blot, qRT-PCR assays, and Dual-luciferase reporter assay were used to verify the interaction among cancer susceptibility 15 (CASC15), miR-338-3p, and RAB14. Cck-8, colony formation assay, and transwell assay were performed to explore and characterize the effects of CASC15 on OS cells. Animal experiments were used to verify the effects of CASC15 in vivo.

Results

Upregulated CASC15 was observed in OS plasma exosomes compared with control, and the same expression was observed in the OS tissues and cell lines. Further assays indicated that CASC15 knockdown could restrain the proliferation, migration, and invasion of OS cells, and inhibit the growth of OS in xenograft models. Furthermore, our results demonstrated CASC15 regulated OS progression via acting as miR-338-3p sponge, and RAB14 was a direct downstream target of miR-338-3p. Rescue experiments verified CASC15 promotes OS cell growth and metastasis by upregulating RAB14 expression.

Conclusion

Overall, our findings indicate that CASC15 plays a key role in OS progression by targeting the miR-338-3p/RAB14 axis and can serve as a possible therapeutic target for OS patients.

Programmed cell death factor 4 (PDCD4), a novel therapy target for metabolic diseases besides cancer

Programmed cell death factor 4 (PDCD4) is originally described as a tumor suppressor gene that exerts antineoplastic effects by promoting apoptosis and inhibiting tumor cell proliferation, invasion, and metastasis. Several investigations have probed the aberrant expression of PDCD4 with the progression of metabolic diseases, such as polycystic ovary syndrome (PCOS), obesity, diabetes, and atherosclerosis. It has been ascertained that PDCD4 causes glucose and lipid metabolism disorders, insulin resistance, oxidative stress, chronic inflammatory response, and gut flora disorders to regulate the progression of metabolic diseases. This review aims to summarize the latest researches to uncover the structure, expression regulation, and biological functions of PDCD4 and to elucidate the regulatory mechanism of the development of tumors and metabolic diseases. This review has emphasized the understanding of the PDCD4 role and to provide new ideas for the research, diagnosis, and treatment of tumors and metabolic diseases.

The critical roles of lncRNAs in the pathogenesis of melanoma

Long non-coding RNAs (lncRNAs) embrace a huge fraction of human transcripts and participate in the pathogenesis of human disorders especially malignant conditions. Malignant melanoma, as the most fatal type of cutaneous malignnacies, is associated with dysregulation of several lncRNAs including PVT1, H19, MALAT1, and CCAT1. Moreover, a portion of lncRNAs are exclusively expressed in melanoma cell lines. Expression levels of several lncRNAs are associated with TNM stage, tumor size and progression of melanoma. Thus, these lncRNAs are regarded as biomarkers for this malignancy. Peripheral transcript levels of a number of lncRNAs, such as PVT1, SNHG5 and SPRY4-IT1, could distinguish melanoma patients from unaffected persons with appropriate sensitivity and specificity values. Moreover, expression levels of numerous lncRNAs in tissue biopsies could differentiate malignant samples from benign samples. Based on the results of both cell line and in vivo studies, lncRNAs regulate critical pathways in the carcinogenesis of melanoma, such as the PI3K/Akt and NF-κB signaling pathways, and are involved in the modulation of response to chemotherapeutic agents. Here we review the existing information on the role of lncRNAs in malignant melanoma.

Long non-coding RNAs: Key regulators in oxaliplatin resistance of colorectal cancer

Colorectal cancer (CRC) is one of the most commonly diagnosed malignancies in the world with high relapse and mortality rates. Although oxaliplatin (OXA), a platinum-based anticancer drug, is widely used in CRC treatment, the resulting chemoresistance dramatically attenuates the drug efficacy and increases the failure rate of this therapy. Thus, the study on OXA-induced chemoresistance is extremely urgent. In recent years, emerging evidence has shown that lncRNAs play irreplaceable roles in drug resistance. However, we only have a limited knowledge of the lncRNAs that are closely related to oxaliplatin resistance in CRC. In present study, we identify and characterize these lncRNAs, including their functions, underlying mechanisms and possible applications.

SOX9-activated PXN-AS1 promotes the tumorigenesis of glioblastoma by EZH2-mediated methylation of DKK1

Increasing evidence has validated the essential regulation of long non-coding RNAs (lncRNAs) in the biological process of tumours. LncRNA PXN-AS1 has been discovered to be as a tumour suppressor in pancreatic cancer; however, its function and mechanism remain greatly unknown in glioblastoma (GBM). Our present study indicated that PXN-AS1 was highly expressed in GBM tissues and cells. Besides, the knock-down of PXN-AS1 was closely associated with the inhibitory proliferation and inducing apoptosis of GBM cells. PXN-AS1 inhibition was also found to restrain GBM tumour growth. Importantly, SOX9 functioned as a transcription factor and activated PXN-AS1 expression, and overexpressed PXN-AS1 rescued the inhibitory role of down-regulated SOX9 in GBM cell growth. Subsequently, it was discovered that PXN-AS1 activated Wnt/β-catenin pathway. DKK1 was widely known as an inhibitor gene of Wnt/β-catenin pathway, and its expression was negatively associated with PXN-AS1 and SOX9. Interestingly, we found that PXN-AS1 could recruit EZH2 to mediate the H3K27me3 level of DKK1 promoter. Restoration experiments manifested that DKK1 knock-down counteracted PXN-AS1 depletion-mediated repression in GBM cell growth. All facts pointed out that PXN-AS1 might be of importance in exploring the therapeutic strategies of GBM.

Herbal melanin inhibits colorectal cancer cell proliferation by altering redox balance, inducing apoptosis, and modulating MAPK signaling

Background

Colorectal carcinoma is one of the most deadly cancers that requests effective and safe chemotherapy. Evaluation of natural product-based anticancer drugs as adjuvant treatment with fewer side effects is largely unexplored research fields. Herbal melanin (HM) is an extract of the seed coats of Nigella sativa that modulates an inflammatory response through toll-like receptor 4 (TLR4). This TLR4 receptor is also involved in the modulation of apoptosis. We therefore explored the anticancer potential of HM and specifically its effect on the molecular mechanisms underlying adenocarcinoma and metastatic colorectal cancer (mCRC) cell death in vitro.

Methods

Cell viability was evaluated using the MTT assay. Cellular reactive oxygen species (ROS), glutathione levels, and apoptotic status were assessed using fluorometric and colorimetric detection methods. HM-induced apoptotic and other signaling pathways were investigated using Western blot technology and mitochondrial transition pore assay kit. TLR4 receptor downregulation and blockade were performed using siRNA technology and neutralizing antibody, respectively.

Results

Our results showed that HM inhibited the proliferation of the colorectal adenocarcinoma HT29 and mCRC SW620 cell lines. Furthermore, HM enhanced ROS production and decreased glutathione levels. HM-induced apoptosis was associated with mitochondrial outer membrane permeability and cytochrome c release, inhibition of the Bcl2 family proteins, and activation of caspase-3/-7. In addition, HM modulated MAPK pathways by activating the JNK pathway and by inhibiting ERK phosphorylation. TLR4 receptor downregulation enhanced HM-induced apoptosis while TLR4 receptor blockade partially alleviated HM-inhibited ERK phosphorylation.

Conclusion

Altogether, these findings indicate that HM exerts pro-apoptotic effects and inhibits MAPK pathway through TLR4 in mCRC and colorectal adenocarcinoma cells, suggesting HM as a promising natural-based drug for the treatment of colorectal cancer.

CASC15 polymorphisms are correlated with cervical cancer susceptibility in Chinese women

Background

Cervical cancer is a frequent, common cancer in women, and causes high cancer‐related deaths among women in our world. Accumulating studies provided an important evidence for long noncoding RNA (lncRNA) polymorphisms in the susceptibility of various cancer. Here, we recruited 494 cervical cancer cases and 504 unrelated controls to assess the relationship between CASC15 (OMIM# 616610) polymorphisms and cervical cancer susceptibility.

Methods

Agena MassARRAY platform was conducted to genotype CASC15 polymorphisms. Odds ratios (ORs) and 95% confidence intervals (CIs) were analyzed through logistic regression to adjust for confounding factors, such as age and gender.

Results

Our study suggested that rs12212674 (NC_000006.12:g.22086845T>A) “A” allele was significantly associated with an increased risk of cervical cancer (OR = 1.31, 95% CI = 1.01–1.69, p = .041). The result was demonstrated in the log‐additive model (OR = 1.32, 95% CI = 1.02–1.72, p = .037). After age stratification, we also found that the “TT” genotype of rs4712653 (NC_000006.11:g.22125964T>C) in CASC15 was interaction with a higher cervical cancer risk in subjects aged ≤51 years in the co‐dominant model (OR = 2.08, 95% CI = 1.02–4.25, p = .044) and the recessive model (OR = 2.11, 95% CI = 1.05–4.24, p = .036). Whereas no significant correlation was found among other SNPs of CASC15 polymorphisms and the risk of cervical cancer. MDR analysis illustrated that the interaction between rs7740084 (NC_000006.11:g.21727531G>A), rs1555529 (NC_000006.11:g.21691704A>G), and rs12212674 had a certain effect on the progress of cervical cancer.

Conclusion

Our results revealed a potential interaction between CASC15 polymorphisms and cervical cancer susceptibility. The results provided important insights into CASC15 function in the development of cervical cancer.

Distinct and shared gene expression for human innate versus adaptive helper lymphoid cells

Innate lymphoid cells (ILCs) are the latest identified innate immune cell family. Given their similarity in transcription factor expression and cytokine secretion profiles, ILCs have been considered as the innate phenocopy of CD4 Th cells. Here, we explored the transcriptome of circulating human ILC subsets as opposed to CD4 Th cell subsets. We describe transcriptomic differences between total ILCs and total CD4 Th cells, as well as between paired innate and adaptive cell subsets (ILC1 vs. Th1; ILC2 vs. Th2; and ILC3 vs. Th17 cells). In particular, we observed differences in expression of genes involved in cell trafficking such as CCR1, CCR6 and CXCR3, innate activation and inhibitory functions, including CD119, 2B4, TIGIT, and CTLA‐4, and neuropeptide receptors, such as VIPR2. Moreover, we report for the first time on distinct expression of long noncoding RNAs (lncRNAs) in innate vs. adaptive cells, arguing for a potential role of lncRNA in shaping human ILC biology. Altogether, our results point for unique, rather than redundant gene organization in ILCs compared to CD4 Th cells, in regard to kinetics, fine‐tuning and spatial organization of the immune response.

Long Non-Coding RNA-CASC15 Promotes Cell Proliferation, Migration, and Invasion by Activating Wnt/β-Catenin Signaling Pathway in Melanoma

BACKGROUND

Melanoma is one of the most aggressive and high mortality skin cancers in the world. Long non-coding RNA-CASC15, as a carcinogen, plays an important role in a variety of tumorigenesis; however, the role and underlying mechanism of CASC15 in melanoma remain unclear.

METHODS

Quantitative real-time polymerase chain reaction was applied to explore CASC15 and β-catenin expression in melanoma tissues and cells. Western blotting was carried out to investigate β-catenin, glycogen synthase kinase-3β, Survivin, Bax, Bcl-2, and epithelial-mesenchymal transition (EMT)-related protein expression level. Cell proliferation, apoptosis, migration, and invasion were observed by colony formation assay, flow cytometry, and transwell migration and invasion assays, respectively. The activity of Wnt/β-catenin signaling pathway was measured by Topflash luciferase reporter assay.

RESULTS

The expression of CASC15 and β-catenin was upregulated in melanoma tissues and cells. Knockdown of CASC15 suppressed Wnt/β-catenin signaling pathway and inhibited β-catenin expression. Furthermore, inhibition of CASC15 decreased proliferation and increased apoptosis of melanoma cells by downregulating Survivin and Bcl-2 and upregulating Bax in A375 and SK-MEL-28 cells. Silencing of CASC15 inhibited migration and invasion of melanoma cells by repressing EMT process.

CONCLUSION

Our study demonstrated that CASC15 promoted the proliferation, migration, and invasion of melanoma cells via activating Wnt/β-catenin signaling pathway, implying that CASC15 might be a potential therapeutic target and prognostic biomarker for melanoma.

LncRNA CASC15 Functions As An Unfavorable Predictor Of Ovarian Cancer Prognosis And Inhibits Tumor Progression Through Regulation Of miR-221/ARID1A Axis

Background

LncRNA cancer susceptibility candidate 15 (CASC15) has been demonstrated to act as an oncogene in different cancers; however, its role in ovarian cancer remains elusive.

Methods

Quantitative real-time PCR (qRT-PCR) was performed to examine the expression of lncRNA CASC15. Kaplan–Meier survival analysis was performed to evaluate the prognostic significance of lncRNA CASC15. CCK-8, soft-agar colony-formation, flow cytometry, transwell migration and invasion assays were used to analyze the biological behavior of lncRNA CASC5 in ovarian cancer. Furthermore, the potential mechanism of lncRNA CAC15 was investigated by bioinformatics analysis, luciferase reporter assay, and biotin pull-down assay.

Results

In this study, we found that the expression of CASC15 was lower in ovarian cancer tissues and cells by qRT-PCR. In addition, low expression of CASC15 was closely correlated with advanced TNM stage, moderate/poor differentiation, and larger size. Moreover, Kaplan–Meier survival analysis showed that patients with low CASC15 expression level had poorer overall survival and progression-free survival than those with high CASC15 expression. Meanwhile, ROC analysis found that CASC15 had diagnostic values to distinguish tumor tissues from nontumorous tissues. Overexpression of CASC15 prohibited the malignancy of ovarian cancer cells, including proliferation, colony formation, cell cycle, migration, and invasion, and promoted cell apoptosis. In addition, bioinformatics analysis, luciferase reporter assay, and biotin pull-down assay confirmed that CASC15 straightly interacted with miR-221. We also observed that ARID1A was a downstream target of miR-221 and CASC15 subsequently exerted its tumor-suppressive effects by regulating the expression of ARID1A in ovarian cancer cells.

Conclusion

Overall, this study firstly elucidated that CASC15 could play a tumor-suppressive role in ovarian cancer by the regulation of CASC15/miR-221/ARID1A axis, which may provide a ponderable prognostic biomarker and promising therapeutic target for treatment of patients with ovarian cancer.

HOXD-AS1 confers cisplatin resistance in gastric cancer through epigenetically silencing PDCD4 via recruiting EZH2

Increasing evidence suggests that dysregulation of long non-coding RNAs (lncRNAs) is implicated in chemoresistance in cancers. However, the function and molecular mechanisms of lncRNAs in gastric cancer chemoresistance are still not well understood. In this study, we aimed to investigate the functional role and the underlying molecular mechanisms of lncRNA HOXD cluster antisense RNA 1 (HOXD-AS1) in cisplatin (DDP) resistance in gastric cancer. Our results revealed that HOXD-AS1 was upregulated in DDP-resistant gastric cancer tissues and cells. Patients with gastric cancer with high HOXD-AS1 expression levels had a poor prognosis. Knockdown of HOXD-AS1 facilitated the sensitivity of DDP-resistant gastric cancer cells to DDP. Additionally, HOXD-AS1 epigenetically silenced PDCD4 through binding to the histone methyltransferase enhancer of zeste homologue 2 (EZH2) on the promoter of PDCD4, thus increasing H3K27me3. More importantly, PDCD4 silencing counteracted HOXD-AS1 knockdown-mediated enhancement of DDP sensitivity in DDP-resistant gastric cancer cells. In summary, HOXD-AS1 led to DDP resistance in gastric cancer by epigenetically suppressing PDCD4 expression, providing a novel therapeutic strategy for patients with gastric cancer with chemoresistance.

The Regulatory Role of Non-coding RNAs on Programmed Cell Death Four in Inflammation and Cancer

Programmed cell death 4 (PDCD4) is a tumor suppressor gene implicated in many cellular functions, including transcription, translation, apoptosis, and the modulation of different signal transduction pathways. The downstream mechanisms of PDCD4 have been well-discussed, but its upstream regulators have not been systematically summarized. Noncoding RNAs (ncRNAs) are gene transcripts with no protein-coding potential but play a pivotal role in the regulation of the pathogenesis of solid tumors, cardiac injury, and inflamed tissue. In recent studies, many ncRNAs, especially microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), were found to interact with PDCD4 to manipulate its expression through transcriptional regulation and function as oncogenes or tumor suppressors. For example, miR-21, as a classic oncogene, was identified as the key regulator of PDCD4 by targeting its 3′-untranslated region (UTR) to promote tumor proliferation, migration, and invasion in colon, breast, and bladder carcinoma. Therefore, we reviewed the recently emerging pleiotropic regulation of PDCD4 by ncRNAs in cancer and inflammatory disorders and aimed to shed light on the mechanisms of associated diseases, which could be conducive to the development of novel treatment strategies for PDCD4-induced diseases.

LncRNA LUCAT1 facilitates tumorigenesis and metastasis of triple-negative breast cancer through modulating miR-5702

Triple-negative breast cancer (TNBC) is a subtype of aggressive breast cancer with high recurrence and poor survival. Emerging evidence has indicated that long non-coding RNAs (lncRNAs) play pivotal roles in the development and progression of multiple cancers. Although there are substantial studies revealing that lung cancer-associated transcript 1 (LUCAT1) functions as a tumor promotor in various human cancers, the molecular mechanism of LUCAT1 in TNBC remains largely to be explored. In our study, we identified that LUCAT1 expression was dramatically enhanced in TNBC samples and cells. High LUCAT1 expression was strongly associated with advanced stages and poor prognosis of TNBC. LUCAT1 contributed to TNBC development through accelerating cell proliferation, cell cycle progression and metastasis as well as attenuating cell apoptosis. Moreover, miR-5702 was proved to directly bind to LUCAT1 and be negatively modulated by LUCAT1. Knockdown of miR-5702 reversed the suppressing influences of LUCAT1 depletion on TNBC progression. In conclusion, it was the first investigation to shed light on the significant function and underlying regulatory mechanism of LUCAT1 in TNBC tumorigenesis. We validated that LUCAT1 induced tumorigenesis and metastasis of TNBC via miR-5702, which provided clues for improving the treatment of TNBC.

Long noncoding RNA CASC15 predicts unfavorable prognosis and exerts oncogenic functions in non-small cell lung cancer

BACKGROUND

Aberrant expression of long non-coding RNA cancer susceptibility 15 (lncRNA CASC15) has been documented in various human tumors, and upregulation of CASC15 is closely correlated with cancer progression. However, the expression profile and potential biological functions of lncRNA CASC15 in non-small cell lung cancer (NSCLC) have not been fully characterized.

METHODS

The expression levels of CASC15 were assessed by qRT-PCR in human NSCLC tissues and by in situ hybridization in NSCLC tissue microarray. The relationship between CASC15 expression and clinical parameters, as well as prognosis were analyzed and validated in TCGA NSCLC datasets. The biological functions of CASC15 were analyzed by CCK-8 assay, cell migration and invasion assay in NSCLC cell lines in vitro. In addition, a mouse xenograft model was established to evaluate the effect of CASC15 knockdown on NSCLC tumor growth in vivo. Epithelial-mesenchymal transition (EMT) related molecules were examined by western blot and immunohistochemistry staining.

RESULTS

We found that CASC15 was upregulated in NSCLC tissues and cell lines. High expression levels of CASC15 were correlated with malignancies and poor survival rate in NSCLC patients. Multivariate analysis revealed that CASC15 was an independent risk factor of prognosis. In addition, we demonstrated that CASC15 knockdown inhibited NSCLC cell proliferation, migration and invasion in vitro. Xenograft model showed CASC15 knockdown significantly suppressed NSCLC tumor growth. Mechanistically, we revealed that CASC15 regulated EMT-related molecules and promoted the NSCLC progression and metastasis.

CONCLUSION

In summary, our findings suggest CASC15 exhibits an oncogenic role in promoting NSCLC tumorigenesis via regulating EMT.

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.

Long noncoding RNA OIP5-AS1 aggravates cell proliferation, migration in gastric cancer by epigenetically silencing NLRP6 expression via binding EZH2

The critical role of long noncoding RNAs (lncRNAs) in the development of multiple cancers has been revealed either functioning as a tumor initiator or a cancer suppressor. A widely recognized OIP5 antisense RNA 1 (lncRNA OIP5-AS1) has been validated to be an essential regulator of the tumorigenesis of various malignancies. Whereas, the potential role and the exact mechanism of lncRNA OIP5-AS1 by which OIP5-AS1 mediates gastric cancer (GC) progression remains vague. Therefore, first our work probed its expression levels in GC cell lines and related normal cells by real-time quantitative polymerase chain reaction. The heightened level of OIP5-AS1 was detected in GC cell lines. In terms of its cellular effects, we performed a series of functional experiments and as presented in the assays, the proliferative potential and motility was diminished. However, more apoptotic cells were induced with the introduction of OIP5-AS1 silencing. Meanwhile, higher Nod-like receptor pyrin domain-containing protein 6 (NLRP6) and enhancer of zeste homolog 2 (EZH2) expression in the GC cells was monitored. Besides, OIP5-AS1 was disclosed to locate mainly in the nucleus. In terms of mechanism, OIP5-AS1 directly bound to EZH2 and obstructed NLRP6 expression, speeding up GC progression.

Malignant Melanoma: Autoimmunity and Supracellular Messaging as New Therapeutic Approaches

OPINION STATEMENT

Melanoma is one of the most aggressive forms of cancer, with a high mortality rate in the absence of a safe and curable therapy. As a consequence, several procedures have been tested over time, with the most recent (immunological and targeted) therapies proving to be effective in some patients. Unfortunately, these new treatment options continue to generate debate related to the therapeutic strategy (intended to maximize the long-term results of patients with melanoma), not only about the monotherapy configuration but also regarding association/succession between distinct therapeutic procedures. As an example, targeted therapy with BRAF inhibitors proved to be effective in advanced BRAF-mutant melanoma. However, such treatments with BRAF inhibitors lead to therapy resistance in half of patients after approximately 6 months. Even if most benign nevi incorporate oncogenic BRAF mutations, they rarely become melanoma; therefore, targeted therapy with BRAF inhibitors should be viewed as an incomplete or perfectible therapy. Another example is related to the administration of immune checkpoint inhibitors/ICIs (anti-CTLA-4 antibodies, anti-PD-1/PD-L1 antibodies), which are successfully used in metastatic melanoma. It is currently believed that CTLA-4 and PD-1 blockade would favor a strong immune response against cancer cells. The main side effects of ICIs are represented by the development of immune-related adverse events, which in some cases can be lethal. These ICI side effects would thus be not only therapeutically counterproductive but also potentially dangerous. Surprisingly, a subset of immune-related adverse events (especially autoimmune toxicity) seems to be clearly correlated with better therapeutic results, perhaps due to an additional therapeutic effect (currently insufficiently studied/exploited). Contrary to the classical approach of cancer (considered until now an uncontrolled division of cells), a very recent and comprehensive theory describes malignancy as a supracellular disease. Cancerous disease would therefore be a disturbed supracellular process (embryogenesis, growth, development, regeneration, etc.), which imposes/coordinates an increased rhythm of cell division, angiogenesis, immunosuppression, etc. Melanoma is presented from such a supracellular perspective to be able to explain the beneficial role of autoimmunity in cancer (autoimmune abortion/rejection of the melanoma-embryo phenotype) and to create premises to better optimize the newly emerging therapeutic options. Finally, it is suggested that the supracellular evolution of malignancy implies complex supracellular messaging (between the cells and host organism), which would be interfaced especially by the extracellular matrix and noncoding RNA. Therefore, understanding and manipulating supracellular messaging in cancer could open new treatment perspectives in the form of digitized (supracellular) therapy.

Long non-coding RNA LINC00662 promotes proliferation and migration in oral squamous cell carcinoma

Background

Although increasing evidence has demonstrated important roles for long non-coding RNAs (lncRNAs) in cancer development, their functions in oral squamous cell carcinoma (OSCC) growth remain largely unknown. Therefore, we aimed to investigate the role of LINC00662 in OSCC.

Methods

The expression of LINC00662 in 61 OSCC tissues and four OSCC cell lines were detected by quantitative reverse-transcription polymerase chain reaction (qRT-PCR). Cell proliferation was detected using Cell Counting Kit-8 (CCK-8) and EdU staining methods. Migration and invasion abilities were analyzed using transwell and wound healing assay. Cell cycle distribution and apoptosis rate were evaluated by flow cytometry. Western blot method was performed to detect protein expression.

Results

We found that the expression of LINC00662 was significantly increased in OSCC tissues, and a higher expression of LINC00662 was detected in larger tumor size, higher stage tumors and with lymph node metastasis. Moreover, overexpression of LINC00662 induced OSCC cell proliferation, increased migration and invasion abilities, and suppressed cell apoptosis. Knockdown of LINC00662 decreased the proliferation, migration, and invasion abilities of OSCC cell, and induced apoptosis. Furthermore, LINC00662 regulated the Wnt/β-catenin pathway.

Conclusion

Our data indicate that LINC00662 may represent a novel indicator of OSCC and may be a potential therapeutic target for diagnosis and therapy.

TUG1 confers cisplatin resistance in esophageal squamous cell carcinoma by epigenetically suppressing PDCD4 expression via EZH2

BACKGROUND

Increasing evidence has suggested the involvement of long non-coding RNA taurine upregulated gene 1 (TUG1) in chemoresistance of cancer treatment. However, its function and molecular mechanisms in esophageal squamous cell carcinoma (ESCC) chemoresistance are still not well elucidated. In the present study, we investigate the functional role of TUG1 in cisplatin (DDP) resistance of ESCC and discover the underlying molecular mechanism.

RESULTS

Our study revealed that TUG1 was up-regulated in DDP-resistant ESCC tissues and cells. High TUG1 expression was correlated with poor prognosis of ESCC patients. TUG1 knockdown improved the sensitivity of ECA109/DDP and EC9706/DDP cells to DDP. Moreover, TUG1 could epigenetically suppress PDCD4 expression via recruiting enhancer of zeste homolog 2. PDCD4 overexpression could mimic the functional role of down-regulated TUG1 in DDP resistance. PDCD4 knockdown counteracted the inductive effect of TUG1 inhibition on DDP sensitivity of ECA109/DDP and EC9706/DDP cells. Furthermore, TUG1 knockdown facilitated DDP sensitivity of DDP-resistant ESCC cells in vivo.

CONCLUSION

TUG1 knockdown overcame DDP resistance of ESCC by epigenetically silencing PDCD4, providing a novel therapeutic target for ESCC.