Screening for long noncoding RNAs associated with oral squamous cell carcinoma reveals the potentially oncogenic actions of DLEU1

Novel insights on oral squamous cell carcinoma management using long non-coding RNAs

Oral squamous cell carcinoma (OSCC) is one of the most prevalent forms of head and neck squamous cell carcinomas (HNSCC) with a poor overall survival rate (about 50%), particularly in cases of metastasis. RNA-based cancer biomarkers are a relatively advanced concept, and non-coding RNAs currently have shown promising roles in the detection and treatment of various malignancies. This review underlines the function of long non-coding RNAs (lncRNAs) in the OSCC and its subsequent clinical implications. LncRNAs, a class of non-coding RNAs, are larger than 200 nucleotides and resemble mRNA in numerous ways. However, unlike mRNA, lncRNA regulates multiple druggable and non-druggable signaling molecules through simultaneous interaction with DNA, RNA, proteins, or microRNAs depending on concentration and localization in cells. Upregulation of oncogenic lncRNAs and down-regulation of tumor suppressor lncRNAs are evident in OSCC tissues and body fluids such as blood and saliva indicating their potential as valuable biomarkers. Targeted inhibition of candidate oncogenic lncRNAs or over-expression of tumor suppressor lncRNAs showed potential therapeutic roles in in-vivo animal models. The types of lncRNAs that are expressed differentially in OSCC tissue and bodily fluids have been systematically documented with specificity and sensitivity. This review thoroughly discusses the biological functions of such lncRNAs in OSCC cell survival, proliferation, invasion, migration, metastasis, angiogenesis, metabolism, epigenetic modification, tumor immune microenvironment, and drug resistance. Subsequently, we addressed the diagnostic and therapeutic importance of lncRNAs in OSCC pre-clinical and clinical systems, providing details on ongoing research and outlining potential future directions for advancements in this field. In essence, this review could be a valuable resource by offering comprehensive and current insights into lncRNAs in OSCC for researchers in fundamental and clinical domains.

Emerging cell cycle related non-coding RNA biomarkers from saliva and blood for oral squamous cell carcinoma

The unnotified or undifferentiable early stages of oral squamous cell carcinoma (OSCC) progression are the prime reasons for late-stage detection and poor survival outcomes of oral cancer. This review summarizes the prior research and recent advancements on the influence of dysregulated non-coding RNA (ncRNA) on cell cycle and their employability as diagnostic and prognostic biomarkers of oral cancer. The literature search was performed using the following keywords: 'serum/saliva non-coding RNAs' and 'serum/saliva non-coding RNAs and cell cycle', 'serum/saliva dysregulated ncRNAs and cell cycle', 'Cdk/CKI and ncRNAs', 'tissue ncRNAs' concerning 'oral cancer''. The compiled data focuses mainly on the diagnostic and prognostic significance of MicroRNAs (miRNAs), Circular RNAs (circRNAs), and Long noncoding RNAs (lncRNAs) on oral cancer and all other cancers as well as subject-relevant articles published in languages other than English are beyond the scope of this review and excluded from the study. Moreover, articles focusing on DNA, protein, and metabolite markers are eliminated from the study. While there exist various potential biomolecules such as DNA, RNA, proteins, metabolites, and specific antigens representing predictive biomarkers in body fluids for oral cancer, this review completely focuses on non-coding RNAs restricted to saliva and blood, picking out a few of the reliable ones amongst the recent investigations based on the sophisticated techniques, cohort, and sensitivity as well as specificity, i.e., salivary miR-1307-5p, miR-3928, hsa_circ_0001874 and ENST00000412740, NR_131012, ENST00000588803, NR_038323, miR-21 in circulation. Thus, further studies are required to clinically confirm the usage of these non-invasive biomarkers in oral cancer.

The human long non-coding RNA LINC00941 and its modes of action in health and disease

Long non-coding RNAs have gained attention in recent years as they were shown to play crucial roles in the regulation of cellular processes, but the understanding of the exact mechanisms is still incomplete in most cases. This is also true for long non-coding RNA LINC00941, which was recently found to be highly upregulated in various types of cancer influencing cell proliferation and metastasis. Initial studies could not elucidate the mode of action to understand the role and real impact of LINC00941 in tissue homeostasis and cancer development. However, recent analyses have demonstrated multiple potential modes of action of LINC00941 influencing the functionality of various cancer cell types. Correspondingly, LINC00941 was proposed to be involved in regulation of mRNA transcription and modulation of protein stability, respectively. In addition, several experimental approaches suggest a function of LINC00941 as competitive endogenous RNA, thus acting in a post-transcriptional regulatory fashion. This review summarizes our recent knowledge about the mechanisms of action of LINC00941 elucidated so far and discusses its putative role in miRNA sequestering processes. In addition, the functional role of LINC00941 in regulating human keratinocytes is discussed to also highlight its role in normal tissue homeostasis tissue aside from its involvement in cancer.

TM4SF1-AS1 inhibits apoptosis by promoting stress granule formation in cancer cells

Long noncoding RNAs (lncRNAs) play pivotal roles in tumor development. To identify dysregulated lncRNAs in gastric cancer (GC), we analyzed genome-wide trimethylation of histone H3 lysine 4 (H3K4me3) to screen for transcriptionally active lncRNA genes in the non-tumorous gastric mucosa of patients with GC and healthy individuals. We found that H3K4me3 at TM4SF1-AS1 was specifically upregulated in GC patients and that the expression of TM4SF1-AS1 was significantly elevated in primary and cultured GC cells. TM4SF1-AS1 contributes to GC cell growth in vitro and in vivo, and its oncogenic function is mediated, at least in part, through interactions with purine-rich element-binding protein α (Pur-α) and Y-box binding protein 1 (YB-1). TM4SF1-AS1 also activates interferon signaling in GC cells, which is dependent on Pur-α and RIG-I. Chromatin isolation by RNA purification (ChIRP)-mass spectrometry demonstrated that TM4SF1-AS1 was associated with several stress granule (SG)-related proteins, including G3BP2, RACK1, and DDX3. Notably, TM4SF1-AS1 promoted SG formation and inhibited apoptosis in GC cells by sequestering RACK1, an activator of the stress-responsive MAPK pathway, within SGs. TM4SF1-AS1-induced SG formation and apoptosis inhibition are dependent on Pur-α and YB-1. These findings suggested that TM4SF1-AS1 contributes to tumorigenesis by enhancing SG-mediated stress adaptation.

The Effects of Umbilical Cord Mesenchymal Stem Cells -Derived Exosomes in Oral Squamous Cell Carcinoma (In vitro Study)

OBJECTIVE

Mesenchymal stem cells (MSCs) derived exosomes offers several advantages as a cell-free therapeutic agents. In this study, Umbilical cord mesenchymal stem cells exosomes (UC-MSCs-exos) effects on oral squamous cell carcinoma (OSCC) cell line was evaluated.

METHODS

UC-MSCs-exos were isolated and co-cultured with OSCC cells and their impact on OSCC was explored by various tests. Comet assay and western blot for cleaved caspase-3 and immunocytochemistry for caspase-8 were used for apoptosis assessment. HO-1 and Nrf2 were used to determine antioxidant levels. Tumor necrosis factor-α and interleukin-6 were assessed as inflammatory biomarkers. HOX transcript antisense intergenic long noncoding RNA (HOTAIR) expression was also evaluated.

RESULTS

In a dose-dependent manner, UC-MSCs-exos reduced the levels of pro-inflammatory cytokines (IL-6 and TNF-α) and induced apoptosis of OSCC in vitro. Meanwhile, we found that UC-MSCs-exos downregulate HOTAIR.

CONCLUSION

UC-MSCs-exos conferred a suppressive role on OSCC in vitro, highlighting a promising therapeutic role. However, the exact potentially involved molecules and molecular mechanisms need to be investigated in further studies.

CXCL12 is expressed by skeletal muscle cells in tongue oral squamous cell carcinoma

BACKGROUND

The CXCL12/CXCR4 axis plays a pivotal role in the progression of various malignancies, including oral squamous cell carcinoma (OSCC). In this study, we aimed to clarify the biological and clinical significance of CXCL12 in the tumor microenvironment of OSCCs.

METHODS

Publicly available single-cell RNA-sequencing (RNA-seq) datasets were used to analyze CXCL12 expression in head and neck squamous cell carcinomas (HNSCC). Immunohistochemical analysis of CXCL12, α-smooth muscle antigen (α-SMA), fibroblast activation protein (FAP) and CD8 was performed in a series of 47 surgically resected primary tongue OSCCs. Human skeletal muscle cells were co-cultured with or without OSCC cells, after which CXCL12 expression was analyzed using quantitative reverse-transcription PCR.

RESULTS

Analysis of the RNA-seq data suggested CXCL12 is abundantly expressed in stromal cells within HNSCC tissue. Immunohistochemical analysis showed that in grade 1 primary OSCCs, CXCL12 is expressed in both tumor cells and muscle cells. By contrast, grade 3 tumors were characterized by disruption of muscle structure and reduced CXCL12 expression. Quantitative analysis of CXCL12-positive areas within tumors revealed that reduced CXCL12 expression correlated with poorer overall survival. Levels of CXCL12 expression tended to inversely correlate α-SMA expression and positively correlate with infiltration by CD8+ lymphocytes, though these relations did not reach statistical significance. CXCL12 was significantly upregulated in muscle cells co-cultured with OSCC cells.

CONCLUSION

Our results suggest that tongue OSCC cells activate CXCL12 expression in muscle cells, which may contribute to tumor progression. However, CXCL12 is reduced in advanced OSCCs due to muscle tissue destruction.

Circulating Long Non-Coding RNAs Could Be the Potential Prognostic Biomarker for Liquid Biopsy for the Clinical Management of Oral Squamous Cell Carcinoma

Long non-coding RNA (lncRNA) have little or no coding potential. These transcripts are longer than 200 nucleotides. Since lncRNAs are master regulators of almost all biological processes, recent evidence proves that aberrantly expressed lncRNAs are pathogenic for oral squamous cell carcinoma (OSCC) and other diseases. LncRNAs influence chromatin modifications, transcriptional modifications, post-transcriptional modifications, genomic imprinting, cell proliferation, invasion, metastasis, and apoptosis. Consequently, they have an impact on the disease transformation, progression, and morbidity in OSCC. Therefore, circulating lncRNAs could be the potential cancer biomarker for the better clinical management (diagnosis, prognosis, and monitoring) of OSCC to provide advanced treatment strategies and clinical decisions. In this review, we report and discuss the recent understandings and perceptions of dysregulated lncRNAs with a focus on their clinical significance in OSCC-disease monitoring and treatment. Evidence clearly indicates that a specific lncRNA expression signature could act as an indicator for the early prediction of diagnosis and prognosis for the initiation, progression, recurrence, metastasis and other clinical prognostic-factors (overall survival, disease-free survival, etc.) in OSCC. The present review demonstrates the current knowledge that all potential lncRNA expression signatures are molecular biomarkers for the early prediction of prognosis in OSCC. Finally, the review provides information about the clinical significance, challenges and limitations of the clinical usage of circulating lncRNAs in a liquid biopsy method in early, pre-symptomatic, sub-clinical, accurate OSCC prognostication. More studies on lncRNA are required to unveil the biology of the inherent mechanisms involved in the process of the development of differential prognostic outcomes in OSCC.

Genome-wide profiling of dysregulated piRNAs and their target genes implicated in oncogenicity of Tongue Squamous Cell Carcinoma

PIWI-interacting RNAs (piRNAs) are single-stranded, 23-36 nucleotide long RNAs that regulate gene expression in the germline but are also detected in some cancers. However, there are no reports yet on piRNA expression in tongue squamous cell carcinoma (TSCC), the most common oral cancer (80-90% percent of all oral cancers). We performed small RNA and whole transcriptome sequencing in H357 tongue cancer and HOK cells (GEO database accession numbers: GSE196674 and GSE196688). We also examined nine published sets of gene expression array data of TSCC tissues from the GEO database to decode piRNAs and their putative targets that may be involved in tumorigenesis. We identified a pool of 16058 and 25677 piRNAs in H357 and HOK, respectively, among which 406 are differentially expressed. We also found that 2094 protein-coding genes are differentially expressed in either TSCC tissues or cell lines. We performed target predictions for these piRNA, pathway and disease function (DF) analyses, as well as qRT-PCR validation of piRNA-target pairs. These experiments revealed one up-regulated (FDFT1) and four down-regulated (OGA, BDH1, TAT, HYAL4) target genes that are enriched in 11 canonical pathways (CPs), with postulated roles in the initiation and progression of TSCC. Downregulation of piR-33422 is predicted to upregulate the FDFT1 gene, which encodes a mevalonate/cholesterol-pathway related farnesyl-diphosphate farnesyltransferase. The FDFT1 appears to be involved in the largest number of oncogenesis-related processes and is interacting with statins, which is a classical cancer drug. This study provides the first evidence of the piRNome of TSCC, which could be investigated further to decode piRNA-mediated gene regulations in malignancy and potential drug targets, such as FDFT1.

LncRNA DLEU1 facilitates the progression of oral squamous cell carcinoma by miR-126-5p/GAB1 axis

Oral squamous cell carcinoma (OSCC) is one of the most frequent malignancies found in head and neck cancers. Dysregulation of lncRNAs has been proposed to be related to the development of OSCC. Here, we investigated the function and probable mechanisms of lncRNA DLEU1 in OSCC. OSCC cell lines and human oral keratinocytes (HOKs) were cultured, while SCC-25 and CAL-27 cells were transfected with the corresponding plasmids. Reverse transcription quantitative PCR (RT-qPCR) and western blot were carried out to measure the RNA and protein levels. Cell proliferation, migration and invasion were evaluated using MTT assays, wound healing and Transwell assays. The StarBase database predicted the interactions between DLEU1 and miR-126-5p, as well as miR-126-5p and GAB1, which were further validated using a dual-luciferase reporter assay. Our results indicated that DLEU1 and GAB1 were upregulated, while miR-126-5p was downregulated in OSCC cells. Silencing DLEU1 reduced OSCC cell proliferation, migration, and invasion, while DLEU1 overexpression had the opposite effects. DLEU1 mediated biological effects in OSCC through binding to miR-126-5p, which directly targeted GAB1. miR-126-5p knockdown rescued the inhibitory function of DLEU1 depletion on proliferation, migration and invasion. Meanwhile, the miR-126-5p mimic exerted suppressive functions in the progression of OSCC, which were neutralized after GAB1 overexpression. In summary, lncRNA DLEU1 targets the miR-126-5p/GAB1 axis to aggravate OSCC progression, providing a novel target for treating OSCC.

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.

DLEU1 promotes cell survival by preventing DYNLL1 degradation in esophageal squamous cell carcinoma

BACKGROUND

Emerging evidence has highlighted the critical roles of long noncoding RNAs (lncRNAs) in tumor development and progression. However, the biological functions and underlying mechanisms of DLEU1 in esophageal squamous cell carcinoma (ESCC) remain unclear.

METHODS

LncRNA expression in ESCC tissues was explored using lncRNA microarray datasets. The functional roles of DLEU1 in ESCC were demonstrated by a series of in vitro and in vivo experiments. RNA pull-down and immunoprecipitation assays were performed to demonstrate the potential mechanisms of DLEU1.

RESULTS

In a screen for differentially expressed lncRNAs in ESCC, we determined that DLEU1 was one of the most overexpressed lncRNAs in ESCC tissues and that upregulated DLEU1 expression was associated with a worse prognosis. Functional assays showed that DLEU1 promoted tumor growth by inhibiting cell apoptosis. Mechanistically, DLEU1 could bind and stabilize DYNLL1 by interfering with RNF114-mediated ubiquitination and proteasomal degradation. The DLEU1/DYNLL1 axis subsequently upregulated antiapoptotic BCL2 and promoted cell survival. Furthermore, DLEU1 upregulation was at least partly facilitated by promoter hypomethylation. Notably, targeting DLEU1 sensitized ESCC cells to cisplatin-induced death.

CONCLUSIONS

Our findings suggest that DLEU1-mediated stabilization of DYNLL1 is critical for cell survival and that the DLEU1/DYNLL1 axis may be a promising therapeutic target for ESCC.

Long noncoding RNA ELDR promotes cell cycle progression in normal oral keratinocytes through induction of a CTCF-FOXM1-AURKA signaling axis

Long noncoding RNAs (lncRNAs) have gained widespread attention as a new layer of regulation in biological processes during development and disease. The lncRNA ELDR (EGFR long noncoding downstream RNA) was recently shown to be highly expressed in oral cancers as compared to adjacent nontumor tissue, and we previously reported that ELDR may be an oncogene as inhibition of ELDR reduces tumor growth in oral cancer models. Furthermore, overexpression of ELDR induces proliferation and colony formation in normal oral keratinocytes (NOKs). In this study, we examined in further detail how ELDR drives the neoplastic transformation of normal keratinocytes. We performed RNA-seq analysis on NOKs stably expressing ELDR (NOK-ELDR), which revealed that ELDR enhances the expression of cell cycle-related genes. Expression of Aurora kinase A and its downstream targets Polo-like kinase 1, cell division cycle 25C, cyclin-dependent kinase 1, and cyclin B1 (CCNB1) are significantly increased in NOK-ELDR cells, suggesting induction of G2/M progression. We further identified CCCTC-binding factor (CTCF) as a binding partner of ELDR in NOK-ELDR cells. We show that ELDR stabilizes CTCF and increases its expression. Finally, we demonstrate the ELDR-CTCF axis upregulates transcription factor Forkhead box M1, which induces Aurora kinase A expression and downstream G2/M transition. These findings provide mechanistic insights into the role of the lncRNA ELDR as a potential driver of oral cancer during neoplastic transformation of normal keratinocytes.

Long Noncoding RNA LINC00941 Promotes Cell Proliferation and Invasion by Interacting with hnRNPK in Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is a prevalent carcinoma of the head, neck and mouth. Recently studies involving the role of long noncoding RNAs (lncRNAs) that play key regulatory roles in altering gene expression has been reported in the context of promoting tumorigenesis. However, the functions of lncRNAs in the context of oral squamous cell carcinoma have not been extensively described. In this study, we report a never identified before lncRNA, LINC00941, which was highly expressed in OSCC tissues and cells. Expression of LINC00941 promoted cell proliferation, migration, invasion, and metastasis of OSCC cells In Vitro by inducing epithelial-mesenchymal transition (EMT) and activating the Wnt/β-catenin signaling cascade. In silico analyses revealed heterogeneous nuclear ribonucleoprotein K (hnRNPK) to be a strong positive regulator of LINC00941 activity. Experimental verification of this association revealed a direct interaction of LINC00941 and hnRNPK to induce cell growth and invasion by activating EMT in OSCC cells. Therefore, our study reports that LINC00941 promotes progression of OSCC by its interaction with hnRNPK, and it may present a promising strategy for diagnosis and treatment of OSCC.

The association of long non-coding RNA in the prognosis of oral squamous cell carcinoma

BACKGROUND

Oral cancer is considered one of the most prevalent cancers in India. This is mainly because India suffers from high usage of tobacco, which is one of the main causative agents of oral cancer, and lacks proper health and sexual hygiene in rural areas.

DISCUSSION

Non-coding RNAs are reported to be involved in the various mechanism and causality of cancer. Numerous reports have identified viable prospects connecting non-coding RNA (ncRNA) with cancer. Specific ncRNAs like long non-coding RNA or lncRNAs are recently being prioritized as potential associations in the cause of cancer.

CONCLUSION

This review aims at presenting a concise perspective on the basics and the recent advancements of the lncRNA research pertaining specifically to oral cancer, its recurrence, and the future possibilities of knowledge it might possess.

Prognostic Role of Long Noncoding RNAs in Oral Squamous Cell Carcinoma: A Meta-Analysis

Long noncoding RNAs (lncRNAs) have emerged as critical regulators of tumor progression, and lncRNA expression levels could serve as a potential molecular biomarker for the prognosis and diagnosis of some cancers. However, the prognostic value of lncRNAs in oral squamous cell carcinoma (OSCC) remains unclear. Thus, a meta-analysis was conducted to explore the potential prognostic value of lncRNAs in OSCC. We systematically searched PubMed, EBSCO, Web of Science, and Elsevier from 2005 to 2021 to identify all published studies that reported the association between lncRNAs and prognosis in OSCC. Then, we used meta-analytic methods to identify the actual effect size of lncRNAs on cancer prognosis. The hazard ratios (HRs) with 95% confidence intervals (95% CIs) were calculated to assess the strength of the association. The reliability of those results was then examined using measures of heterogeneity and testing for selective reporting biases. According to the inclusion and exclusion criteria, a total of 17 studies were eligible in our meta-analysis, involving 1384 Asian patients. The results identified a statistically significant association of high lncRNA expression with poor overall survival [adjusted pooled hazard ratio (AHR) = 1.52; 95% confidence interval (CI): [1.26–1.84], p ≤ 0.001]. The present meta-analysis demonstrated that lncRNA expression might be used as a predictive prognostic biomarker for Asian patients with OSCC.

An optimized protocol for total RNA isolation from archived formalin-fixed paraffin-embedded tissues to identify the long non-coding RNA in oral squamous cell carcinomas

Approximately 93% of the human genome is translated into RNAs, of which only 2% code for proteins and the rest 98% are noncoding RNAs. Long non-coding RNAs (lncRNAs) are a class of non-coding RNAs of > 200 nucleotides length that are emerging as novel players in the field of cancer diagnostics or prognostics. Recently, lncRNAs are known to be associated with oral squamous cell carcinomas (OSCC). The demonstration of stable lncRNA has been a challenge in formalin-fixed paraffin-embedded tissues (FFPE). The survivability and expression level of lncRNA in FFPE tissues compared with fresh tissues is not well documented in the literature. Hence, we designed the current pilot study with the main aim to optimize modified TRI (Total RNA isolation) reagent RNA isolation protocol to identify the lncRNA expression in archived FFPE tissues of OSCC in comparison to the standard RNA isolation kit method. The findings of our study demonstrated that the RNA quantity and quality were comparatively better with the optimized TRI reagent modified protocol than the standard RNA isolation kit method. Furthermore, ct (cycle threshold) values after reverse-transcription and qRT-PCR (Quantitative Real time PCR) were comparable and almost equal in both the methods for normal mucosa (control) and OSCC samples.

Long Non-Coding RNA (lncRNA) in Oral Squamous Cell Carcinoma: Biological Function and Clinical Application

Simple Summary

Increasing evidence has revealed the regulatory roles of long non-coding RNAs (lncRNAs) in the initiation and progress of oral squamous cell carcinoma (OSCC). As some novel lncRNA-targeted techniques combined with immune checkpoint therapies have emerged, they provide a new strategy for OSCC treatment. This review summarizes current knowledge regarding the involvement of lncRNAs in OSCC along with their possible use as diagnostic and prognostic biomarker and therapeutic targets.

Abstract

Oral squamous cell carcinoma (OSCC) is a type of malignancy with high mortality, leading to poor prognosis worldwide. However, the molecular mechanisms underlying OSCC carcinogenesis have not been fully understood. Recently, the discovery and characterization of long non-coding RNAs (lncRNAs) have revealed their regulatory importance in OSCC. Abnormal expression of lncRNAs has been broadly implicated in the initiation and progress of tumors. In this review, we summarize the functions and molecular mechanisms regarding these lncRNAs in OSCC. In addition, we highlight the crosstalk between lncRNA and tumor microenvironment (TME), and discuss the potential applications of lncRNAs as diagnostic and prognostic tools and therapeutic targets in OSCC. Notably, we also discuss lncRNA-targeted therapeutic techniques including CRISPR-Cas9 as well as immune checkpoint therapies to target lncRNA and the PD-1/PD-L1 axis. Therefore, this review presents the future perspectives of lncRNAs in OSCC therapy, but more research is needed to allow the applications of these findings to the clinic.

Overexpression of lncRNA DLEU1 in Gastric Cancer Tissues Compared to Adjacent Non-Tumor Tissues

PURPOSE

Gastric cancer (GC) is caused by environmental factors and genetic changes of protein-coding- and non-coding sequences, which entail short non-coding RNAs (microRNAs) and long non-coding RNAs (lncRNAs). DLEU1 (deleted in lymphocytic leukemia 1), as an effective lncRNA located on chromosome 14.3q 13, modulates the nuclear factor-kB (NF-kB) signaling pathway. This gene usually plays an oncogenic role in the tumorigenesis of multiple types of cancer. The present study examined the expression level of DLEU1 and its association with clinical-pathological characteristics in GC.

METHODS

Total RNA of 100 specimens was extracted by TRIzol reagent. After cDNA synthesis, qRT-PCR analysis was performed to measure the expression level of the DLEU1 gene and the obtained data were analyzed by SPSS 16.0.

RESULTS

The relative expression level of DLEU1 significantly increased in tumor specimens compared to the normal tumor margin specimens. The biomarker index of lncRNA DLEU1 was 0.7 in tumor tissues. The observed high expression level of DLEU1 was pertinent to the pathological progressive TNM stage, lymph node metastasis, differentiation degree, patient's age and lifestyle, and Helicobacter pylori infection in GC patients.

CONCLUSION

The obtained findings suggested that DLEU1 acts as an oncogene in GC and might be a new target for gene therapy of GC.

DLEU1 promotes oral squamous cell carcinoma progression by activating interferon-stimulated genes

Long noncoding RNAs (lncRNAs) are deeply involved in cancer development. We previously reported that DLEU1 (deleted in lymphocytic leukemia 1) is one of the lncRNAs overexpressed in oral squamous cell carcinoma (OSCC) cells, where it exhibits oncogenic activity. In the present study, we further clarified the molecular function of DLEU1 in the pathogenesis of OSCC. Chromatin immunoprecipitation-sequencing (ChIP-seq) analysis revealed that DLEU1 knockdown induced significant changes in the levels of histone H3 lysine 4 trimethylation (H3K4me3) and H3K27 acetylation (H3K27ac) in OSCC cells. Notably, DLEU1 knockdown suppressed levels of H3K4me3/ H3K27ac and expression of a number of interferon-stimulated genes (ISGs), including IFIT1, IFI6 and OAS1, while ectopic DLEU1 expression activated these genes. Western blot analysis and reporter assays suggested that DLEU1 upregulates ISGs through activation of JAK-STAT signaling in OSCC cells. Moreover, IFITM1, one of the ISGs induced by DLUE1, was frequently overexpressed in primary OSCC tumors, and its knockdown inhibited OSCC cell proliferation, migration and invasion. These findings suggest that DLEU1 exerts its oncogenic effects, at least in part, through activation of a series ISGs in OSCC cells.

FOXD2-AS1 Predicts Dismal Prognosis for Oral Squamous Cell Carcinoma and Regulates Cell Proliferation

The roles of long noncoding RNA FOXD2 adjacent opposite strand RNA 1 (FOXD2-AS1) in oral squamous cell carcinoma (OSCC) remain largely unknown. Here, the Atlas of Noncoding RNAs in Cancer online database was utilized to analyze the expression and clinical significance of FOXD2-AS1 in OSCC. Then, the cell proliferation of FOXD2-AS1-silenced OSCC cells (CAL-27) was assessed by MTT and clone formation experiments. FOXD2-AS1-coexpressed genes were enriched and analyzed via circlncRNAnet and Metascape tools. Finally, key molecules of the signal pathways of the aforementioned coexpressed genes were verified by western blotting. We found that FOXD2-AS1 was significantly highly expressed in OSCC tissues, and correlated with poor pathological grade and prognosis in patients with OSCC. Cell viability and clone formation ability were significantly inhibited after the knockdown of FOXD2-AS1. A total of 32 coexpressed genes of FOXD2-AS1 were identified, and those genes were enriched in the cell cycle. In conclusion, FOXD2-AS1 may be served as a potential prognostic indicator and therapeutic target for OSCC.

Silencing novel long non-coding RNA FKBP9P1 represses malignant progression and inhibits PI3K/AKT signaling of head and neck squamous cell carcinoma in vitro

Background

Long non-coding RNAs (lncRNAs) play key roles in human cancers. In our previous study, we demonstrated that lncRNA FKBP prolyl isomerase 9 pseudogene 1 (FKBP9P1) was highly expressed in head and neck squamous cell cancer (HNSCC) tissues. However, its functional significance remains poorly understood. In the present study, we identify the role and potential molecular biologic mechanisms of FKBP9P1 in HNSCC.

Methods

Quantitative real-time polymerase chain reaction was used to detect the expression of FKBP9P1 in HNSCC tissues, matched adjacent normal tissues, human HNSCC cells (FaDu, Cal-27, SCC4, and SCC9), and human immortalized keratinocytes cell HaCaT (normal control). Cal-27 and SCC9 cells were transfected with sh-FKBP9P1-1, sh-FKBP9P1-2, and normal control (sh-NC) lentivirus. Cell counting kit-8 assay, colony formation assay, wound healing assay, and trans-well assay were used to explore the biologic function of FKBP9P1 in HNSCC cells. Furthermore, western blotting was used to determine the mechanism of FKBP9P1 in HNSCC progression. Chi-squared test was performed to assess the clinical significance among FKBP9P1 high-expression and low-expression groups. Survival analyses were performed using the Kaplan-Meier method and assessed using the log-rank test. The comparison between two groups was analyzed by Student t test, and comparisons among multiple samples were performed by one-way analysis of variance and a Bonferroni post hoc test.

Results

FKBP9P1 expression was significantly up-regulated in HNSCC tissues (tumor vs. normal, 1.914 vs. 0.957, t = 7.746, P < 0.001) and cell lines (P < 0.01 in all HNSCC cell lines). Besides, the median FKBP9P1 expression of HNSCC tissues (1.677) was considered as the threshold. High FKBP9P1 level was correlated with advanced T stage (P = 0.022), advanced N stage (P = 0.036), advanced clinical stage (P = 0.018), and poor prognosis of HNSCC patients (overall survival, P = 0.002 and disease-free survival, P < 0.001). Knockdown of FKBP9P1 led to marked repression in proliferation, migration, and invasion of HNSCC cells in vitro (P all < 0.01). Mechanistically, silencing FKBP9P1 was observed to restrain the PI3K/AKT signaling pathway.

Conclusions

Silencing lncRNA FKBP9P1 represses HNSCC progression and inhibits PI3K/AKT (phosphatidylinositol 3 kinase/AKT Serine/Threonine Kinase) signaling in vitro. Therefore, FKBP9P1 could be a potential new target for the diagnosis and treatment of HNSCC patients.

Knockdown of lncRNA DLEU1 inhibits the tumorigenesis of oral squamous cell carcinoma via regulation of miR‑149‑5p/CDK6 axis

Oral squamous cell carcinoma (OSCC) is a frequent malignant tumor worldwide. Long non-coding RNAs (lncRNAs) are known to play key roles in different types of cancer, including OSCC. It was previously reported that lncRNA deleted in lymphocytic leukemia 1 (DLEU1) is notably upregulated in OSCC; however, the role of DLEU1 in OSCC remains unclear. Gene and protein expression levels in OSCC cells were detected by reverse transcription-quantitative PCR and western blotting, respectively, in the present study. A Transwell assay was performed to measure cell migration and invasion. Flow cytometry was used to detect cell apoptosis, and the dual-luciferase reporter assay was applied to confirm the interaction between DLEU1, microRNA (miR)-149-5p and CDK6 in OSCC cells. DLEU1 expression was negatively associated with the survival rate of patients with OSCC. In addition, silencing of DLEU1 notably inhibited the proliferation of OSCC cells by inducing apoptosis. Meanwhile, DLEU1 directly bound to miR-149-5p, and CDK6 was found to be the direct target of miR-149-5p. Furthermore, DLEU1 knockdown-induced inhibition of OSCC cell proliferation was significantly reversed by the miR-149-5p antagomir. Knockdown of lncRNA DLEU1 reversed the proliferation of OSCC cells via regulation of the miR-149-5p/CDK6 axis. Thus, DLEU1 may serve as a novel target for treating OSCC.

Diverse roles of bitter melon (Momordica charantia) in prevention of oral cancer

Oral squamous cell carcinoma (OSCC) is one of the common lethal malignancies which is increasing rapidly in the world. Increasing risks from alcohol and tobacco habits, lack of early detection markers, lack of effective chemotherapeutic agents, recurrence and distant metastasis make the disease more complicated to manage. Laboratory-based studies and epidemiological studies indicate important roles of nutraceuticals to manage different cancers. The plant bitter melon (Momordica charantia) is a good source of nutrients and bio-active phytochemicals such as triterpenoids, triterpene glycosides, phenolic acids, flavonoids, lectins, sterols and proteins. The plant is widely grown in Asia, Africa, and South America. Bitter melon has traditionally been used as a folk medicine and Ayurvedic medicine in Asian culture to treat diseases such as diabetes, since ancient times. The crude extract and some of the isolated pure compounds of bitter melon show potential anticancer effects against different cancers. In this review, we shed light on its effect on OSCC. Bitter melon extract has been found to inhibit cell proliferation and metabolism, induce cell death and enhance the immune defense system in the prevention of OSCC in vitro and in vivo. Thus, bitter melon may be used as an attractive chemopreventive agent in progression towards OSCC clinical study.

Upregulation of Serum lncRNA DLEU1 Predicts Progression of Premalignant Endometrial Lesion and Unfavorable Clinical Outcome of Endometrial Cancer

OBJECTIVE

Long non-coding RNAs (lncRNAs) play a critical role in tumorigenesis. Upregulation of lncRNA deleted in lymphocytic leukemia 1 (DLEU1) has been reported in endometrial cancer (EC) tissues. This prospective study aimed to determine the potential clinical significance of serum lncRNA DLEU1 in EC.

METHODS

The serum lncRNA DLEU1 level was detected in EC patients, patients with endometrial hyperplasia and healthy controls by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Then its clinical value in EC was further evaluated.

RESULTS

Our results demonstrated that serum lncRNA DLEU1 levels were significantly increased in patients with EC, and serum lncRNA DLEU1 showed good performance for discriminating EC patients from patients with endometrial hyperplasia and healthy controls. In addition, EC patients with advanced clinicopathological features had higher circulating lncRNA DLEU1 level than those with favorable clinical characteristics. Moreover, EC patients in the high serum lncRNA DLEU1 group suffered worse overall survival and disease-free survival than those in the low serum lncRNA DLEU1 group. Furthermore, multivariate cox regression analysis displayed that the serum lncRNA DLEU1 served as an independent prognostic factor for EC.

CONCLUSIONS

Collectively, our study suggests that serum lncRNA DLEU1 is a novel and promising biomarker for prognostic estimation of EC.

Long non-coding RNA ELDR enhances oral cancer growth by promoting ILF3-cyclin E1 signaling

Oral squamous cell carcinoma (OSCC) is the sixth most common cancer with a 5-year overall survival rate of 50%. Thus, there is a critical need to understand the disease process, and to identify improved therapeutic strategies. Previously, we found the long non-coding RNA (lncRNA) EGFR long non-coding downstream RNA (ELDR) induced in a mouse tongue cancer model; however, its functional role in human oral cancer remained unknown. Here, we show that ELDR is highly expressed in OSCC patient samples and in cell lines. Overexpression of ELDR in normal non-tumorigenic oral keratinocytes induces cell proliferation, colony formation, and PCNA expression. We also show that ELDR depletion reduces OSCC cell proliferation and PCNA expression. Proteomics data identifies the RNA binding protein ILF3 as an interacting partner of ELDR. We further show that the ELDR-ILF3 axis regulates Cyclin E1 expression and phosphorylation of the retinoblastoma (RB) protein. Intratumoral injection of ELDR-specific siRNA reduces OSCC and PDX tumor growth in mice. These findings provide molecular insight into the role of ELDR in oral cancer and demonstrate that targeting ELDR has promising therapeutic potential.

DLEU1: A Functional Long Noncoding RNA in Tumorigenesis

BACKGROUND

LncRNA DLEU1 participates in various biological processes, playing an indispensable role in the pathophysiology of human diseases, especially in tumorigenesis and other processes. Besides, it may represent a promising target for biotherapy in numerous tumors. The aim of this review was to reveal the pathophysiological functions and mechanisms of lncRNA DLEU1 in different types of cancer.

METHODS

In this review, current studies concerning the biological functions and mechanisms of DLEU1 in tumor development are summarized and analyzed; the related researches are collected through a systematic retrieval of PubMed.

RESULTS

DLEU1 is a novel cancer-associated lncRNA that has been proved to be abnormally elevated in various malignancies, containing osteosarcoma, glioma, glioblastoma multiforme, hepatocellular carcinoma, bladder cancer, cervical cancer, non-small cell lung cancer, pancreatic ductal adenocarcinoma, colorectal cancer, oral squamous cell carcinoma, endometrial cancer, gastric cancer, Burkitt lymphoma and ovarian carcinoma. Besides, lncRNA LDEU1 has been demonstrated involving in the procession of proliferation, migration, invasion and inhibition of apoptosis of cancer cells.

CONCLUSION

Long non-coding RNA DLEU1 is likely to represent an available biomarker or a potential therapeutic target in multiple tumors.

Long noncoding RNAs in head and neck squamous cell carcinoma: biological functions and mechanisms

Head and neck squamous cell carcinoma (HNSCC) is the primary malignant tumor of the oral cavity, larynx, nasopharynx, esophagus and tongue. Although several novel therapeutic methods for HNSCC have been developed, the final therapeutic effect on the patient is still not satisfactory. Thus, it is imperative that scientists identify novel distinguishable markers with specific molecular characteristics that can be used in therapeutic and prognostic evaluation. Previous reports have shown that long noncoding RNAs (lncRNAs) are important regulators of gene expression in many cancers, including head and neck squamous cell carcinomas. Translational studies of lncRNAs in HNSCC are urgently required before their application as a treatment can be realized. We aimed to address the most relevant findings on lncRNAs as biomarkers or treatment targets in head and neck squamous cell carcinoma and to summarize their discovered pathways and mechanisms of action to reveal the possible future applications of these novel biomarkers in clinical translational research.

PI3K/AKT/mTOR pathway-related long non-coding RNAs: roles and mechanisms in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common tumors worldwide with high prevalence and lethality. The oncogenic phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway is a classic dysregulated pathway involved in the pathogenesis of HCC. However, the underlying mechanism for how PI3K/AKT/mTOR pathway aberrantly activates HCC has not been entirely elucidated. The recognition of the functional roles of long non-coding RNAs (lncRNAs) in PI3K/AKT/mTOR signaling axis sheds light on a new dimension to our understanding of hepatocarcinogenesis. In this review, we comprehensively summarize 67 dysregulated PI3K/AKT/mTOR pathway-related lncRNAs in HCC. Many studies have indicated that the 67 dysregulated lncRNAs show oncogenic or anti-oncogenic effects in HCC by regulation on epigenetic, transcriptional and post-transcriptional levels and they play pivotal roles in the initiation of HCC in diverse biological processes like proliferation, metastasis, drug resistance, radio-resistance, energy metabolism, autophagy and so on. Besides, many of these lncRNAs are associated with clinicopathological features and clinical prognosis in HCC, which may provide a potential future application in the diagnosis and therapy of HCC.

LINC00941 promotes oral squamous cell carcinoma progression via activating CAPRIN2 and canonical WNT/β-catenin signaling pathway

Dysregulation of long non-coding RNAs (lncRNAs) has been implicated in many cancer developments. Previous studies showed that lncRNA LINC00941 was aberrantly expressed in oral squamous cell carcinoma (OSCC). However, its role in OSCC development remains elusive. In this study, we demonstrated that in OSCC cells, EP300 activates LINC00941 transcription through up-regulating its promoter H3K27ac modification. Up-regulated LINC00941 in turn activates CAPRIN2 expression by looping to CAPRIN2 promoter. Functional assays suggest that both LINC00941 and CAPRIN2 play pivotal roles in promoting OSCC cell proliferation and colony formation. In vivo assay further confirmed the role of LINC00941 in promoting OSCC cell tumour formation. Lastly, we showed that the role of LINC00941 and CAPRIN2 in OSCC progression was mediated through activating the canonical WNT/β-catenin signaling pathway. Thus, LINC00941/CAPRIN2/ WNT/β-catenin signaling pathway provides new therapeutic targets for OSCC treatment.

An RNA-sequencing-based transcriptome for a significantly prognostic novel driver signature identification in bladder urothelial carcinoma

Bladder cancer (BC) is the ninth most common malignancy worldwide. Bladder urothelial carcinoma (BLCA) constitutes more than 90% of bladder cancer (BC). The five-year survival rate is 5–70%, and patients with BLCA have a poor clinical outcome. The identification of novel clinical molecular markers in BLCA is still urgent to allow for predicting clinical outcomes. This study aimed to identify a novel signature integrating the three-dimension transcriptome of protein coding genes, long non-coding RNAs, microRNAs that is related to the overall survival of patients with BLCA, contributing to earlier prediction and effective treatment selection, as well as to the verification of the established model in the subtypes identified. Gene expression profiling and the clinical information of 400 patients diagnosed with BLCA were retrieved from The Cancer Genome Atlas (TCGA) database. A univariate Cox regression analysis, robust likelihood-based survival modelling analysis and random forests for survival regression and classification algorithms were used to identify the critical biomarkers. A multivariate Cox regression analysis was utilized to construct a risk score formula with a maximum area under the curve (AUC = 0.7669 in the training set). The significant signature could classify patients into high-risk and low-risk groups with significant differences in overall survival time. Similar results were confirmed in the test set (AUC = 0.645) and in the entire set (AUC = 0.710). The multivariate Cox regression analysis indicated that the five-RNA signature was an independent predictive factor for patients with BLCA. Non-negative matrix factorization and a similarity network fusion algorithm were applied for identifying three molecular subtypes. The signature could separate patients in every subtype into high- and low- groups with a distinct difference. Gene set variation analysis of protein-coding genes associated with the five prognostic RNAs demonstrated that the co-expressed protein-coding genes were involved in the pathways and biological process of tumourigenesis. The five-RNA signature could serve as to some degree a reliable independent signature for predicting outcome in patients with BLCA.

Nobiletin inhibits cell growth through restraining aerobic glycolysis via PKA-CREB pathway in oral squamous cell carcinoma

BACKGROUND/AIM

Nobiletin is a polymethoxylated flavone enriched in Citrus and is used as an important drug in traditional Chinese medicine for various kinds of diseases. Among its multiple functions, it has shown that nobiletin inhibits proliferation of various cancer cells. However, it is unclear whether nobiletin inhibits the growth of oral squamous cell carcinoma (OSCC) cells.

MATERIALS AND METHODS

We explored the antitumor effects of nobiletin in TCA-8113 and CAL-27 oral squamous cells. The Cell Counting Kit-8 (CCK8) assay was used to measure cell vitality. Flow cytometry was performed to measure the number of cells in the various phases of the cell cycle. PCR and Western blot were applied to determine mRNA and protein expression, respectively.

RESULTS

Nobiletin inhibited proliferation of TCA-8113 and CAL-27 cells via inducing cell cycle arrest at the G1 phase. In addition, the levels of phosphorylated-PKA and phosphorylated-CREB were reduced in nobiletin-treated TCA-8113 and CAL-27 cells. Importantly, our results showed that nobiletin treatment resulted in impaired mitochondrial function and altered glucose consumption, and pyruvate and lactate production. Lastly, nobiletin was found to inhibit the generation of xenografts in vivo. Interestingly, administration of 50 μmol/L Sp-cAMP, a potent PKA activator, rescued all phenotypes caused by nobiletin.

CONCLUSIONS

Nobiletin inhibits OSCC cell proliferation in a mitochondria-dependent manner, indicating that it may have a promising role in cancer treatment and attenuation of drug resistance.

RP11-874J12.4 promotes oral squamous cell carcinoma tumorigenesis via the miR-19a-5p/EBF1 axis

BACKGROUND

Oral squamous cell carcinoma (OSCC) ranks as the fifth most frequent cancer worldwide, and the recurrence and migration of OSCC still pose large threats to patients. Long non-coding RNAs (lncRNAs) have recently emerged as crucial players in cancer development, and it is of great significance to understand the regulatory nexus of lncRNAs in OSCC.

METHODS

Here, we identified a novel lncRNA, RP11-874J12.4, which is ectopically expressed in OSCC and facilitates OSCC.

RESULTS

RP11-874J12.4 directly binds to and regulates miR-19a-5p. Interestingly, RP11-874J12.4 and miR-19a-5p form a negative regulatory loop that inhibits the expression of miR-19a-5p in OSCC. The expression of an oncogenic transcription factor, EBF1, is unleashed in OSCC due to the low expression of miR-19a-5p, which promotes the growth and migration of OSCC.

CONCLUSION

Our data illustrate a regulatory axis of RP11-874J12.4/miR-19a-5P/EBF1 and an inhibitory loop with RP11-874J12.4 and miR-19a-5p. These data provide insights into the tumorigenesis of OSCC and the novel drug targets for OSCC.

Role of epigenetic in leukemia: From mechanism to therapy

Epigenetic variations can play remarkable roles in different normal and abnormal situations. Such variations have been shown to have a direct role in the pathogenesis of various diseases either through inhibition of tumor suppressor genes or increasing the expression of oncogenes. Enzymes involving in epigenetic machinery are the main actors in tuning the epigenetic-based controls on gene expressions. Aberrant expression of these enzymes can trigger big chaos in the cellular gene expression networks and finally lead to cancer progression. This situation has been shown in different types of leukemia, where high or low levels of an epigenetic enzyme are partly or highly responsible for the involvement or progression of a disease. DNA hypermethylation, different histone modifications, and aberrant miRNA expressions are three main epigenetic variations, which have been shown to play a role in leukemia progression. Epigenetic based treatments now are considered as novel and effective therapies in order to decrease the abnormal epigenetic modifications in patient cells. Different epigenetic-based approaches have been developed and tested to inhibit or reverse the unusual expression of epigenetic agents in leukemia. Acute myeloid leukemia (AML), the most prevalent acute leukemia in adults, is anaggressive hematological malignancy arising in hematopoietic stem and progenitor cells. With the exception of a few specific AML subtypes, the mainstays of treatment have not significantly changed over the last 20 years, and are still based on standard cytotoxic chemotherapy. In this review, we will discuss the recent development of therapeutics specifically targeting these key epigenetic programs in AML, describe their mechanism of action and present their current clinical development. Finally, we will discuss the opportunities presented by epigenetically targeted therapy in AML and will highlight future challenges ahead for the AML community, to ensure that this novel therapeutics are optimally translated into clinical practice and result in clinical improvement for AML patients.

SP1-DLEU1-miR-4429 feedback loop promotes cell proliferative and anti-apoptotic abilities in human glioblastoma

Mounting studies have revealed that long non-coding RNA (lncRNA) deleted in lymphocytic leukemia 1 (DLEU1) positively regulated the initiation and development of various human malignant tumors. Nevertheless, the function and mechanism of DLEU1 in human glioblastoma multiforme (GBM) remain elusive and ill-defined. The current study was designed to highlight the functional role and disclose the underlying molecular mechanism by which DLEU1 regulated GBM development. We found that DLEU1 was up-regulated in GBM and DLEU1 knockdown significantly inhibited GBM cell proliferation and induced apoptosis. As predicted by bioinformatics analysis and validated in mechanistic assays, SP1 could bind to the promoter region of DLEU1 to activate DLEU1 transcription. Additionally, miR-4429 was verified as a target gene of DLEU1 and negatively modulated by DLEU1. More importantly, miR-4429 overexpression repressed the mRNA and protein levels of SP1 via binding to the 3'UTR of SP1. Overexpression of SP1 or miR-4429 inhibitor could partly abolish the effect of DLEU1 knockdown on cell viability and apoptosis in GBM. Accordingly, our experimental data revealed that SP1-DLEU1-miR-4429 formed a feedback loop to promote GBM development, providing a new evidence for the role of DLEU1 in GBM.

Small nucleolar RNA host gene 3 facilitates cell proliferation and migration in oral squamous cell carcinoma via targeting nuclear transcription factor Y subunit gamma

Oral squamous cell carcinoma (OSCC) has been reported to be the most common oral carcinoma. Emerging evidence has revealed the key role that long noncoding RNAs (lncRNAs) play in numerous malignancies, including OSCC. LncRNA small nucleolar RNA host gene 3 (SNHG3) has been reported as an oncogenic factor in some cancers. Nonetheless, the role of SNHG3 in OSCC has never been clarified. In this study, we analyzed the expression patterns of SNHG3 in OSCC through quantitative real-time polymerase chain reaction. It was revealed that the expression level of SNHG3 was remarkably elevated in OSCC cell lines compared with the nontumor cell line. It was demonstrated by functional experiments that SNHG3 knockdown notably inhibited cell proliferation and migration in OSCC. RNA immunoprecipitation, RNA pull down, and messenger RNA (mRNA) stability test verified that SNHG3 decoyed ELAV like RNA-binding protein 1 (ELAVL1) and therefore stabilized nuclear transcription factor Y subunit gamma (NFYC) mRNA to upregulate the expression levels of NFYC in OSCC cells. At last, it was confirmed by rescue experiments that the inhibiting impacts of SNHG3 knockdown on OSCC cell proliferation and migration could be partly revived by NFYC overexpression. Besides, we validated that Wnt/β-catenin pathway was also involved in SNHG3-regulated OSCC progression. In conclusion, SNHG3 might serve as a novel biomarker for OSCC.

RALBP1 regulates oral cancer cells via Akt and is a novel target of miR-148a-3p and miR-148b-3p

BACKGROUND

Malignant tumors arising from the epithelium of the oral cavity are termed as squamous cell carcinomas (OSCC). The aim of the current work was to understand the role of an isoform of RAS-like protein (RAL), RALBP1, in mediating squamous cell tumorigenesis. The study also aims to understand epigenetic modifications of RALBP1 mediated through microRNA-148a/b-3p.

METHODS

Biopsies of tumor and healthy tissues from 25 patients with OSCC were collected and subjected to RNA and protein extraction to confirm upregulation of RLBP1 in tumor tissues. Expression of RLBP1 was silenced in SCC-9, using shRNA, and HN6 was transfected with plasmid bearing genes for RLBP1 over expression. Tumorigenic traits such as increased glucose uptake, aerobic glycolysis, enhanced cellular survival, cell migration, and invasion were assessed. Probable, molecular machinery involved in the upregulation was also assessed using Western blots. Using Target Scan tool, the miRNAs targeting RLBP1 were identified. Rescue of phenotypes in presence of miRNAs were also evaluated.

RESULTS

Over expression of RLBP1 was associated with increased glucose uptake and aerobic glycolysis mediated ATP synthesis. The cells divided at a faster rate with a higher rate of migration and invasion phenotype. miR-148a/b-3p were found to target RLBP1 and rescued RLBP1 mediated phenotype.

CONCLUSION

RLBP1 may mediate squamous cell tumorigenesis in oral cavity, independently of the RAS protein and through Akt. miR-148a/b-3p functions as a tumor suppressor by targeting RLBP1.

Down-regulation of hsa_circ_0092125 is related to the occurrence and development of oral squamous cell carcinoma

Circular RNA plays an important role in regulating tumour development and progression and can serve as a biomarker for cancer. This study was performed to investigate the clinical significance of hsa_circ_0092125 expression in oral squamous cell carcinoma (OSCC). The expression of hsa_circ_0092125 in OSCC tissues and cell lines was determined by reverse transcription-quantitative PCR analysis. The association between hsa_circ_0092125 expression and clinicopathological data was determined by χ² test. Overall survival (OS) curves were created using Kaplan-Meier survival analysis, and the differences were examined by log-rank test. Moreover, univariate and multivariate Cox analysis were employed to evaluate the risk factors of the OSCC prognosis. The expression of hsa_circ_0092125 was significantly down-regulated in OSCC tissues and cell lines. A low expression of hsa_circ_0092125 was associated with clinicopathological factors in OSCC patients, including tumour size, TNM stage, and lymph node metastasis. Kaplan-Meier survival analysis indicated that the OS time was shorter in OSCC patients with a lower hsa_circ_0092125 expression level than in those with a higher expression level. In addition, univariate and multivariate Cox analysis identified lower hsa_circ_0092125 expression, tumour size, TNM stage, and lymph node metastasis as independent risk factors for the OSCC prognosis. Thus, down-regulated expression of hsa_circ_0092125 might serve as a biomarker of the OSCC prognosis.

Long noncoding RNA DLEU1 aggravates glioma progression via the miR-421/MEF2D axis

Background

Long noncoding RNA (lncRNA) deleted in lymphocytic leukemia 1 (DLEU1) was reported to be involved in the development and progression of multiple cancers. However, the accurate expression pattern, biological function and potential molecular mechanism of DLEU1 in glioma are not yet known. The present study investigated the role of DLEU in the development and progression of glioma, as well as the potential mechanism played by DLEU1 in glioma.

Materials and methods

The levels of DLEUI in glioma tissues and cell lines were examined using quantitative real-time PCR. The potential effects of DLEU1 on the proliferation, mobility, invasion and apoptosis of glioma cells were evaluated using corresponding in vitro experiments. The association between DLEU1 and microRNA (miR)-421 was also determined using luciferase reporter activity and RNA immunoprecipitation (RIP) assays.

Results

The results revealed that DLEU1 was significantly upregulated in glioma tissues and cell lines. Increased DLEU1 was positively associated with the high-grade carcinoma (III-IV). Functional studies revealed that knockdown of DLEU1 expression by siRNA led to decreased proliferation, migration and invasion and increased apoptosis in human glioma cells. Furthermore, luciferase reporter activity and RIP assays confirmed that DLEUI could act as a competing endogenous RNA (ceRNA) for miR-421 that functioned as a tumor suppressor in glioma. Moreover, inhibition miR-421 partially restored the effect of DLEU1 knockdown on the glioma cells. DLEU1 could regulate myocyte enhancer factor 2D (MEF2D) expression, a known target of miR-421 in glioma cells.

Conclusion

Taken together, these findings suggested that DLEU1 regulated MEF2D expression to promote glioma progression by sponging miR-421 and that DLEU1 might be a potential therapeutic target for glioma.

Long non-coding RNA deleted in lymphocytic leukaemia 1 promotes hepatocellular carcinoma progression by sponging miR-133a to regulate IGF-1R expression

Long non‐coding RNA (lncRNA) deleted in lymphocytic leukaemia 1 (DLEU1) was reported to be involved in the occurrence and development of multiple cancers. However, the exact expression, biological function and underlying mechanism of DLEU1 in hepatocellular carcinoma (HCC) remain unclear. In this study, real‐time quantitative polymerase chain reaction (qRT‐PCR) in HCC tissues and cell lines revealed that DLEU1 expression was up‐regulated, and the increased DLEU1 was closely associated with advanced tumour‐node‐metastasis stage, vascular metastasis and poor overall survival. Function experiments showed that knockdown of DLEU1 significantly inhibited HCC cell proliferation, colony formation, migration and invasion, and suppressed epithelial to mesenchymal transition (EMT) process via increasing the expression of E‐cadherin and decreasing the expression of N‐cadherin and Vimentin. Luciferase reporter gene assay and RNA immunoprecipitation (RIP) assay demonstrated that DLEU1 could sponge miR‐133a. Moreover, miR‐133a inhibition significantly reversed the suppression effects of DLEU1 knockdown on HCC cells. Besides, we found that silenced DLEU1 significantly decreased insulin‐like growth factor 1 receptor (IGF‐1R) expression (a target of miR‐133a) and its downstream signal PI3K/AKT pathway in HCC cells, while miR‐133a inhibitor partially reversed this trend. Furthermore, DLEU1 knockdown impaired tumour growth in vivo by regulating miR‐133a/IGF‐1R axis. Collectively, these findings indicate that DLEU1 promoted HCC progression by sponging miR‐133a to regulate IGF‐1R expression. Deleted in lymphocytic leukaemia 1/miR‐133a/IGF‐1R axis may be a novel target for treatment of HCC.

Long non-coding RNAs in Oral squamous cell carcinoma: biologic function, mechanisms and clinical implications

There is growing evidence that regions of the genome that cannot encode proteins play an important role in diseases. These regions are usually transcribed into long non-coding RNAs (lncRNAs). LncRNAs, little or no coding potential, are defined as capped transcripts longer than 200 nucleotides. New sequencing technologies have shown that a large number of aberrantly expressed lncRNAs are associated with multiple cancer types and indicated they have emerged as an important class of pervasive genes during the development and progression of cancer. However, the underlying mechanism in cancer is still unknown. Therefore, it is necessary to elucidate the lncRNA function. Notably, many lncRNAs dysregulation are associated with Oral squamous cell carcinoma (OSCC) and affect various aspects of cellular homeostasis, including proliferation, survival, migration or genomic stability. This review expounds the up- or down-regulation of lncRNAs in OSCC and the molecular mechanisms by which lncRNAs perform their function in the malignant cell. Finally, the potential of lncRNAs as non-invasive biomarkers for OSCC diagnosis are also described. LncRNAs hold promise as prospective novel therapeutic targets, but more research is needed to gain a better understanding of their biologic function.

Overexpression of ZEB2-AS1 promotes epithelial-to-mesenchymal transition and metastasis by stabilizing ZEB2 mRNA in head neck squamous cell carcinoma

The long noncoding RNAs (lncRNAs) have been increasingly appreciated as key players underlying tumourigenesis and hold great potentials as prognostic biomarkers and therapeutic targets. However, their roles in head neck squamous cell carcinoma (HNSCC) have remained incompletely known. Here, we sought to reveal the oncogenic roles and clinical significance of a tumour‐associated lncRNA, zinc finger E‐box binding homeobox 2 antisense RNA 1 (ZEB2‐AS1), in HNSCC. ZEB2‐AS1 was aberrantly overexpressed in a fraction of HNSCC samples. Its overexpression significantly associated with large tumour size, cervical node metastasis and reduced overall and disease‐free survival. Antisense oligonucleotides (ASO)‐mediated ZEB2‐AS1 depletion markedly inhibited cell proliferation, migration and invasion while triggered apoptosis in HNSCC cells in part via modulating ZEB2 mRNA stability. Enforced overexpression of ZEB2 largely attenuated the phenotypic changes resulted from ZEB2‐AS1 inhibition except the impaired cell proliferation. In addition, ZEB2‐AS1 was required for TGF‐β1‐induced epithelial‐mesenchymal transition (EMT) in vitro. Significantly reduced tumour growth and lung metastasis were observed in ZEB2‐AS1‐depleted cells in HNSCC xenograft animal models. Taken together, our findings reveal that overexpression of ZEB2‐AS1 associates with tumour aggressiveness and unfavourable prognosis by serving as a putative oncogenic lncRNA and a novel prognostic biomarker in HNSCC.

Upregulation of DLEU1 expression by epigenetic modification promotes tumorigenesis in human cancer

The function of DLEU1 in human cancer is largely unknown. The Cancer Genome Atlas data were applied to identify the landscape of differential genes between tumor tissues and normal tissues, which was further validated by our cohort data and pan-cancer data including 33 cancer types with 11,060 patients. Next, DLEU1 was selected to validate the novel finding and result showed that it promoted tumorigenesis in vitro and in vivo. Mechanistically, DLEU1 promotes SRP4 expression via increasing H3K27ac enrichment to SRP4 locus epigenetically. Moreover, epigenetic modification leads to upregulation of DLEU1 expression via decreased DNA methylation and increased H3K27ac and H3K4me3 histone modification in its locus. Finally, high expression of DLEU1 correlates with worse prognosis not only in specific cancer type patients but also in patients in the pan-cancer cohort. In summary, the work broadens the function landscape of known long noncoding RNAs in human cancer and provides novel insights into their roles in tumorigenesis.