Long noncoding RNA HAS2-AS1 mediates hypoxia-induced invasiveness of oral squamous cell carcinoma

Value of long non-coding RNA HAS2-AS1 as a diagnostic and prognostic marker of glioma

BACKGROUND

Glioma presents high incidence and poor prognosis, and therefore more effective treatments are needed. Studies have confirmed that long non-coding RNAs (lncRNAs) basically regulate various human diseases including glioma. It has been theorized that HAS2-AS1 serves as an lncRNA to exert an oncogenic role in varying cancers. This study aimed to assess the value of lncRNA HAS2-AS1 as a diagnostic and prognostic marker for glioma.

METHODS

The miRNA expression data and clinical data of glioma were downloaded from the TCGA database for differential analysis and survival analysis. In addition, pathological specimens and specimens of adjacent normal tissue from 80 patients with glioma were used to observe the expression of HAS2-AS1. The receiver operating characteristic (ROC) curve was used to analyze the diagnostic ability and prognostic value of HAS2-AS1 in glioma. Meanwhile, a Kaplan-Meier survival curve was plotted to evaluate the survival of glioma patients with different HAS2-AS1 expression levels.

RESULTS

HAS2-AS1 was significantly upregulated in glioma tissues compared with normal tissue. The survival curves showed that overexpression of HAS2-AS1 was associated with poor overall survival (OS) and progression-free survival (PFS). Several clinicopathological factors of glioma patients, including tumor size and WHO grade, were significantly correlated with HAS2-AS1 expression in tissues. The ROC curve showed an area under the curve (AUC) value of 0.863, indicating that HAS2-AS1 had good diagnostic value. The ROC curve for the predicted OS showed an AUC of 0.906, while the ROC curve for predicted PFS showed an AUC of 0.88. Both suggested that overexpression of HAS2-AS1 was associated with poor prognosis.

CONCLUSIONS

Normal tissues could be clearly distinguished from glioma tissues based on HAS2-AS1 expression. Moreover, overexpression of HAS2-AS1 indicated poor prognosis in glioma patients. Therefore, HAS2-AS1 could be used as a diagnostic and prognostic marker for glioma.

Effects of Hyaluronan on Breast Cancer Aggressiveness

The expression of the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) in breast cancer cells is critical for determining tumor aggressiveness and targeting therapies. The presence of such receptors allows for the use of antagonists that effectively reduce breast cancer growth and dissemination. However, the absence of such receptors in triple-negative breast cancer (TNBC) reduces the possibility of targeted therapy, making these tumors very aggressive with a poor outcome. Cancers are not solely composed of tumor cells, but also include several types of infiltrating cells, such as fibroblasts, macrophages, and other immune cells that have critical functions in regulating cancer cell behaviors. In addition to these cells, the extracellular matrix (ECM) has become an important player in many aspects of breast cancer biology, including cell growth, motility, metabolism, and chemoresistance. Hyaluronan (HA) is a key ECM component that promotes cell proliferation and migration in several malignancies. Notably, HA accumulation in the tumor stroma is a negative prognostic factor in breast cancer. HA metabolism depends on the fine balance between HA synthesis by HA synthases and degradation yielded by hyaluronidases. All the different cell types present in the tumor can release HA in the ECM, and in this review, we will describe the role of HA and HA metabolism in different breast cancer subtypes.

Hyaluronan in the Cancer Cells Microenvironment

The presence of the glycosaminoglycan hyaluronan in the extracellular matrix of tissues is the result of the cooperative synthesis of several resident cells, that is, macrophages and tumor and stromal cells. Any change in hyaluronan concentration or dimension leads to a modification in stiffness and cellular response through receptors on the plasma membrane. Hyaluronan has an effect on all cancer cell behaviors, such as evasion of apoptosis, limitless replicative potential, sustained angiogenesis, and metastasis. It is noteworthy that hyaluronan metabolism can be dramatically altered by growth factors and matrikines during inflammation, as well as by the metabolic homeostasis of cells. The regulation of HA deposition and its dimensions are pivotal for tumor progression and cancer patient prognosis. Nevertheless, because of all the factors involved, modulating hyaluronan metabolism could be tough. Several commercial drugs have already been described as potential or effective modulators; however, deeper investigations are needed to study their possible side effects. Moreover, other matrix molecules could be identified and targeted as upstream regulators of synthetic or degrading enzymes. Finally, co-cultures of cancer, fibroblasts, and immune cells could reveal potential new targets among secreted factors.

Particle Exclusion Assay: A Tool for Measuring Hyaluronan Pericellular Matrix

Hyaluronan (HA) is the most abundant glycosaminoglycan in the extracellular matrix, and its deposition is strictly related to changes in cellular behaviors, such as cell migration, proliferation, and adhesion. Pericellular HA is abundant in a variety of cell types, and its amount could reflect specific conditions, thus suggesting a particular cellular status.Particle exclusion assay is a useful tool to visualize pericellular matrices with a high HA content, simply employing microscope image analysis. This approach is quick and allows to visualize the presence of a clear pericellular region around single cells, where fixed red blood cells are excluded if the pericellular matrix has been deposited.

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.

Regulating the Expression of HIF-1α or lncRNA: Potential Directions for Cancer Therapy

Previous studies have shown that tumors under a hypoxic environment can induce an important hypoxia-responsive element, hypoxia-induced factor-1α (HIF-1α), which can increase tumor migration, invasion, and metastatic ability by promoting epithelial-to-mesenchymal transition (EMT) in tumor cells. Currently, with the deeper knowledge of long noncoding RNAs (lncRNAs), more and more functions of lncRNAs have been discovered. HIF-1α can regulate hypoxia-responsive lncRNAs under hypoxic conditions, and changes in the expression level of lncRNAs can regulate the production of EMT transcription factors and signaling pathway transduction, thus promoting EMT progress. In conclusion, this review summarizes the regulation of the EMT process by HIF-1α and lncRNAs and discusses their relationship with tumorigenesis. Since HIF-1α plays an important role in tumor progression, we also summarize the current drugs that inhibit tumor progression by modulating HIF-1α.

Construction and verification of a novel hypoxia-related lncRNA signature related with survival outcomes and immune microenvironment of bladder urothelial carcinoma by weighted gene co-expression network analysis

Background: Bladder urothelial carcinoma (BLCA) is a common malignant tumor with the greatest recurrence rate of any solid tumor. Hypoxia is crucial in the growth and immune escape of malignant tumors. To predict clinical outcomes and immunological microenvironment of patients with BLCA, a hypoxia-related long non-coding RNA (HRlncRNA) signature was established.

Methods: The Cancer Genome Atlas (TCGA) provided us with the differentially expressed profile of HRlncRNAs as well as clinical data from patients with BLCA, and we used weighted gene co-expression network analysis (WGCNA) to identify gene modules associated with malignancies.

Results: Finally, Cox analysis revealed that HRlncRNAs, which comprised 13 lncRNAs, were implicated in the predictive signature. The training, testing, and overall cohorts of BLCA patients were divided into the low-risk group and high-risk group based on the median of the risk score. The Kaplan–Meier curves revealed that BLCA patients with a high-risk score had a poor prognosis, and the difference between subgroups was statistically significant. The receiver operating characteristic curves revealed that this signature outperformed other strategies in terms of predicting ability. Multivariate analysis revealed that the risk score was an independent prognostic index for overall survival (HR = 1.411; 1.259–1.582; p < 0.001). Then, a nomogram with clinicopathological features and risk score was established. This signature could effectively enhance the capacity to predict survival, according to the calibration plots, stratification, and clinical analysis. The majority of Kyoto Encyclopedia of Genes and Genomes (KEGG) were WNT, MAPK, and ERBB signaling pathways. Two groups had different immune cell subtypes, immune checkpoints, immunotherapy response, and anti-tumor drug sensitivity, which might result in differing survival outcomes. We then validated the differential expression of signature-related genes between tumor and normal tissues using TCGA paired data.

Conclusion: This prognostic signature based on 13 HRlncRNAs may become a novel and potential prognostic biomarker, providing more accurate clinical decision-making and effective treatment for BLCA patients.

The role of lncRNAs and XIST in oral cancer

Long non-coding RNA (lncRNA) plays a significant role in the pathogenesis of many human malignant tumors, including oral cancer. LncRNA can act as a gene regulator in a variety of cancers. It regulates the growth of malignant cells via many cellular signal pathways such as the PI3K (phosphoinositide 3-kinase)/AKT (α-serine/threonine-protein kinase) pathway. In this review, we have analyzed the role of lncRNAs, such as lncRNA X inactive specific transcript (XIST), in oral cancer, including its effects on the proliferation, apoptosis, invasion, migration, and resistance to chemotherapy of oral cancer. We have also focused on the role of lncRNA XIST as the core of X chromosome inactivation. Here, we provide a brief overview of the role of many kinds of lncRNAs, including XIST, which provides a theoretical basis for the study of the role of XIST in oral cancer. Our review may provide a new direction for the study of the occurrence, development, and prognosis of oral cancer and provide a new target for its treatment.

CD44 Depletion in Glioblastoma Cells Suppresses Growth and Stemness and Induces Senescence

Glioblastoma multiforme (GBM) is a lethal brain tumor, characterized by enhanced proliferation and invasion, as well as increased vascularization and chemoresistance. The expression of the hyaluronan receptor CD44 has been shown to correlate with GBM progression and poor prognosis. Here, we sought to elucidate the molecular mechanisms by which CD44 promotes GBM progression by knocking out (KO) CD44, employing CRISPR/Cas9 gene editing in U251MG cells. CD44-depleted cells exhibited an impaired proliferation rate, as shown by the decreased cell numbers, decreased Ki67-positive cell nuclei, diminished phosphorylation of CREB, and increased levels of the cell cycle inhibitor p16 compared to control cells. Furthermore, the CD44 KO cells showed decreased stemness and increased senescence, which was manifested upon serum deprivation. In stem cell-like enriched spheres, RNA-sequencing analysis of U251MG cells revealed a CD44 dependence for gene signatures related to hypoxia, the glycolytic pathway, and G2 to M phase transition. Partially similar results were obtained when cells were treated with the γ-secretase inhibitor DAPT, which inhibits CD44 cleavage and therefore inhibits the release of the intracellular domain (ICD) of CD44, suggesting that certain transcriptional responses are dependent on CD44-ICD. Interestingly, the expression of molecules involved in hyaluronan synthesis, degradation, and interacting matrix proteins, as well as of platelet-derived growth factor (PDGF) isoforms and PDGF receptors, were also deregulated in CD44 KO cells. These results were confirmed by the knockdown of CD44 in another GBM cell line, U2990. Notably, downregulation of hyaluronan synthase 2 (HAS2) impaired the hypoxia-related genes and decreased the CD44 protein levels, suggesting a CD44/hyaluronan feedback circuit contributing to GBM progression.

Noncoding RNAs as sensors of tumor microenvironmental stress

The tumor microenvironment (TME) has been demonstrated to modulate the biological behavior of tumors intensively. Multiple stress conditions are widely observed in the TME of many cancer types, such as hypoxia, inflammation, and nutrient deprivation. Recently, accumulating evidence demonstrates that the expression levels of noncoding RNAs (ncRNAs) are dramatically altered by TME stress, and the dysregulated ncRNAs can in turn regulate tumor cell proliferation, metastasis, and drug resistance. In this review, we elaborate on the signal transduction pathways or epigenetic pathways by which hypoxia-inducible factors (HIFs), inflammatory factors, and nutrient deprivation in TME regulate ncRNAs, and highlight the pivotal roles of TME stress-related ncRNAs in tumors. This helps to clarify the molecular regulatory networks between TME and ncRNAs, which may provide potential targets for cancer therapy.

The natural antisense transcript HAS2-AS1 regulates breast cancer cells aggressiveness independently from hyaluronan metabolism

Hyaluronan (HA) is a ubiquitous extracellular matrix component playing a crucial role in the regulation of cell behaviors, including cancer. Aggressive breast cancer cells tend to proliferate, migrate and metastatize. Notably, triple-negative breast cancer cells lacking the expression of estrogen receptor (ER) as well as progesterone receptor and HER2 are more aggressive than ER-positive ones. As currently no targeted therapy is available for triple-negative breast cancer, the identification of novel therapeutic targets has a high clinical priority. In ER-negative cells, tumoral behavior can be reduced by inhibiting HA synthesis or silencing the enzymes involved in its metabolism, such as HA synthase 2 (HAS2). HAS2-AS1 is a long non-coding RNA belonging to the natural antisense transcript family which is known to favor HAS2 gene expression and HA synthesis, thus bolstering malignant progression in brain, ovary, and lung tumors. As the role of HAS2-AS1 has not yet been investigated in breast cancer, in this work we report that ER-positive breast cancers had lower HAS2-AS1 expression compared to ER-negative tumors. Moreover, the survival of patients with ER-negative tumors was higher when the expression of HAS2-AS1 was elevated. Experiments with ER-negative cell lines as MDA-MB-231 and Hs 578T revealed that the overexpression of either the full-length HAS2-AS1 or its exon 2 long or short isoforms alone, strongly reduced cell viability, migration, and invasion, whereas HAS2-AS1 silencing increased cell aggressiveness. Unexpectedly, in these ER-negative cell lines, HAS2-AS1 is involved neither in the regulation of HAS2 nor in HA deposition. Finally, transcriptome analysis revealed that HAS2-AS1 modulation affected several pathways, including apoptosis, proliferation, motility, adhesion, epithelial to mesenchymal transition, and signaling, describing this long non-coding RNA as an important regulator of breast cancer cells aggressiveness.

Impact of Non-Coding RNAs on Chemotherapeutic Resistance in Oral Cancer

Drug resistance in oral cancer is one of the major problems in oral cancer therapy because therapeutic failure directly results in tumor recurrence and eventually in metastasis. Accumulating evidence has demonstrated the involvement of non-coding RNAs (ncRNAs), such as microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), in processes related to the development of drug resistance. A number of studies have shown that ncRNAs modulate gene expression at the transcriptional or translational level and regulate biological processes, such as epithelial-to-mesenchymal transition, apoptosis, DNA repair and drug efflux, which are tightly associated with drug resistance acquisition in many types of cancer. Interestingly, these ncRNAs are commonly detected in extracellular vesicles (EVs) and are known to be delivered into surrounding cells. This intercellular communication via EVs is currently considered to be important for acquired drug resistance. Here, we review the recent advances in the study of drug resistance in oral cancer by mainly focusing on the function of ncRNAs, since an increasing number of studies have suggested that ncRNAs could be therapeutic targets as well as biomarkers for cancer diagnosis.

Identification and Validation of a Hypoxia-Immune-Based Prognostic mRNA Signature for Oral Squamous Cell Carcinoma

BACKGROUND

Oral squamous cell carcinoma (OSCC) is a commonly encountered head and neck malignancy. Increasing evidence shows that there are abnormal immune response and chronic cell hypoxia in the development of OSCC. However, there is a lack of a reliable hypoxia-immune-based gene signature that may serve to accurately prognosticate OSCC.

METHODS

The mRNA expression data of OSCC patients were extracted from the TCGA and GEO databases. Hypoxia status was identified using the t-distributed Stochastic Neighbor Embedding (t-SNE) algorithm. Both ESTIMATE and single-sample gene-set enrichment analysis (ssGSEA) were used for further evaluation of immune status. The DEGs in different hypoxia and immune status were determined, and univariate Cox regression was used to identify significantly prognostic genes. A machine learning method, least absolute shrinkage and selection operator (LASSO) Cox regression analysis, allowed us to construct prognostic gene signature to predict the overall survival (OS) of OSCC patients.

RESULTS

A total of 773 DEGs were identified between hypoxia high and low groups. According to immune cell infiltration, patients were divided into immune high, medium, and low groups and immune-associated DEGs were identified. A total of 193 overlapped DEGs in both immune and hypoxia status were identified. With the univariate and LASSO Cox regression model, eight signature mRNAs (FAM122C, RNF157, RANBP17, SOWAHA, KIAA1211, RIPPLY2, INSL3, and DNAH1) were selected for further calculation of their respective risk scores. The risk score showed a significant association with age and perineural and lymphovascular invasion. In the GEO validation cohort, a better OS was observed in patients from the low-risk group in comparison with those in the high-risk group. High-risk patients also demonstrated different immune infiltration characteristics from the low-risk group and the low-risk group showed potentially better immunotherapy efficacy in contrast to high-risk ones.

CONCLUSION

The hypoxia-immune-based gene signature has prognostic potential in 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.

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.

The role of the multifaceted long non-coding RNAs: A nuclear-cytosolic interplay to regulate hyaluronan metabolism

In the extracellular matrix (ECM), the glycosaminoglycan (GAG) hyaluronan (HA) has different physiological roles favouring hydration, elasticity and cell survival. Three different isoforms of HA synthases (HAS1, 2, and 3) are responsible for the production of HA. In several pathologies the upregulation of HAS enzymes leads to an abnormal HA accumulation causing cell dedifferentiation, proliferation and migration thus favouring cancer progression, fibrosis and vascular wall thickening. An intriguing new player in HAS2 gene expression regulation and HA production is the long non-coding RNA (lncRNA) hyaluronan synthase 2 antisense 1 (HAS2-AS1). A significant part of mammalian genomes corresponds to genes that transcribe lncRNAs; they can regulate gene expression through several mechanisms, being involved not only in maintaining the normal homeostasis of cells and tissues, but also in the onset and progression of different diseases, as demonstrated by the increasing number of studies published through the last decades. HAS2-AS1 is no exception: it can be localized both in the nucleus and in the cytosol, regulating cancer cells as well as vascular smooth muscle cells behaviour.

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Hyaluronan is a component of the extracellular matrix and is synthetised by three isoenzymes named HAS1, 2, and 3.

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In several pathologies an upregulation of HAS2 leads to an abnormal accumulation of HA.

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The long non-coding RNA is a new specific epigenetic regulator of HAS2.

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In the nucleus HAS2-AS1 modulates chromatin structure around HAS2 promoter increasing transcription.

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In the cytosol, HAS2-AS1 can interact with several miRNAs altering the expression of several genes as well as can stabilise HAS2 mRNA forming RNA: RNA duplex.

Tumor microenvironment and immune evasion in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC), an aggressive malignancy, is characterized by high morbidity and low survival rates with limited therapeutic options outside of regional surgery, conventional cytotoxic chemotherapy, and irradiation. Increasing studies have supported the synergistic role of the tumor microenvironment (TME) in cancer advancement. The immune system, in particular, plays a key role in surveillance against the initiation, development, and progression of HNSCC. The understanding of how neoplastic cells evolve and evade the immune system whether through self-immunogenicity manipulation, or expression of immunosuppressive mediators, provides the foundation for the development of advanced therapies. Furthermore, the crosstalk between cancer cells and the host immune system have a detrimental effect on the TME promoting angiogenesis, proliferation, and metastasis. This review provides a recent insight into the role of the key inflammatory cells infiltrating the TME, with a focus on reviewing immunological principles related to HNSCC, as cancer immunosurveillance and immune escape, including a brief overview of current immunotherapeutic strategies and ongoing clinical trials.

LncRNA HAS2-AS1 Promotes Glioblastoma Proliferation by Sponging miR-137

GBM (Glioblastoma multiform) is the most malignant tumor type of the central nervous system and has poor diagnostic and clinical outcomes. LncRNAs (Long non-coding RNAs) have been reported to participate in multiple biological and pathological processes, but their underlying mechanism remains poorly understood. Here, we aimed to explore the role of the lncRNA HAS2-AS1 (HAS2 antisense RNA 1) in GBM. GSE103227 was analyzed, and qRT-PCR was performed to measure the expression of HAS2-AS1 in GBM. FISH (Fluorescence in situ hybridization) was performed to verify the localization of HAS2-AS1. The interaction between HAS2-AS1 and miR-137 (microRNA-137) was predicted by LncBook and miRcode followed by dual-luciferase reporter assays, and the relationships among HAS2-AS1, miR-137 and LSD1 (lysine-specific demethylase 1) were assessed by WB (western blot) and qRT-PCR. Colony formation and CCK-8 (cell counting kit-8) assays were performed as functional tests. In vivo, nude mice were used to confirm the function of HAS2-AS1. HAS2-AS1 expression was upregulated in GBM cell lines, and HAS2-AS1 was localized mainly in the cytoplasm. In vitro, high HAS2-AS1 expression promoted proliferation, and knockdown of HAS2-AS1 significantly inhibited proliferation. Furthermore, HAS2-AS1 functioned as a ceRNA (competing endogenous RNA) of miR-137, leading to the disinhibition of its downstream target LSD1. The miR-137 level was downregulated by HAS2-AS1 overexpression and upregulated by HAS2-AS1 knockdown. In a subsequent study, LSD1 expression was negatively regulated by miR-137, while miR-137 reversed the LSD1 expression levels caused by HAS2-AS1. These results were further supported by the nude mouse tumorigenesis experiment; compared with xenografts with high HAS2-AS1 expression, the group with low levels of HAS2-AS1 exhibited suppressed proliferation and better survival. We conclude that lncRNA HAS2-AS1 promotes proliferation by functioning as a miR-137 decoy to increase LSD1 levels and thus might be a possible biomarker for GBM.

Long Non-Coding RNAs as Functional Codes for Oral Cancer: Translational Potential, Progress and Promises

Oral cancer is one of the leading malignant tumors worldwide. Despite the advent of multidisciplinary approaches, the overall prognosis of patients with oral cancer is poor, mainly due to late diagnosis. There is an urgent need to develop valid biomarkers for early detection and effective therapies. Long non-coding RNAs (lncRNAs) are recognized as key elements of gene regulation, with pivotal roles in various physiological and pathological processes, including cancer. Over the past few years, an exponentially growing number of lncRNAs have been identified and linked to tumorigenesis and prognosis outcomes in oral cancer, illustrating their emerging roles in oral cancer progression and the associated signaling pathways. Herein, we aim to summarize the most recent advances made concerning oral cancer-associated lncRNA, and their expression, involvement, and potential clinical impact, reported to date, with a specific focus on the lncRNA-mediated molecular regulation in oncogenic signaling cascades and oral malignant progression, while exploring their potential, and challenges, for clinical applications as biomarkers or therapeutic targets for oral cancer.

The transcription factor USF1 promotes glioma cell invasion and migration by activating lncRNA HAS2-AS1

Objective: The role of lncRNAs in tumor has been widely concerned. The present study took HAS2-AS1 (the antisense RNA 1 of HAS2) as a starting point to explore its expression in glioma and its role in the process of migration and invasion, providing a strong theoretical basis for mining potential therapeutic targets of glioma.

Methods: Clinical data of glioma were obtained from The Cancer Genome Atlas (TCGA) database and differentially expressed lncRNAs were analyzed by edgeR. The hTFtarget database was used to predict the upstream transcription factors of HAS2-AS1 and the JASPAR website was used to predict the binding sites of human upstream transcription factor 1 (USF1) and HAS2-AS1. qRT-PCR was used to detect the expressions of HAS2-AS1 and USF1 in glioma tissues and cell lines. The effects of silencing HAS2-AS1 on the migration and invasion of cancer cells were verified by wound healing and Transwell invasion assays. The chromatin immunoprecipitation (ChIP) and dual luciferase reporter assays were applied to demonstrate the binding of USF1 and HAS2-AS1 promoter region. Western blot was used to detect the expressions of epithelial–mesenchymal transition (EMT)-related proteins.

Results: HAS2-AS1 was highly expressed in glioma tissues and cells, and was significantly associated with poor prognosis. Silencing HAS2-AS1 expression inhibited glioma cell migration, invasion and EMT. USF1 was highly expressed in glioma and positively correlated with HAS2-AS1. The transcription of HAS2-AS1 was activated by USF1 via binding to HAS2-AS1 promoter region, consequently potentiating the invasion and migration abilities of glioma cells.

Conclusion: These results suggested that the transcription factor USF1 induced up-regulation of lncRNA HAS2-AS1 and promoted glioma cell invasion and migration.

Androgens regulate ovarian gene expression by balancing Ezh2-Jmjd3 mediated H3K27me3 dynamics

Conventionally viewed as male hormone, androgens play a critical role in female fertility. Although androgen receptors (AR) are transcription factors, to date very few direct transcriptional targets of ARs have been identified in the ovary. Using mouse models, this study provides three critical insights about androgen-induced gene regulation in the ovary and its impact on female fertility. First, RNA-sequencing reveals a number of genes and biological processes that were previously not known to be directly regulated by androgens in the ovary. Second, androgens can also influence gene expression by decreasing the tri-methyl mark on lysine 27 of histone3 (H3K27me3), a gene silencing epigenetic mark. ChIP-seq analyses highlight that androgen-induced modulation of H3K27me3 mark within gene bodies, promoters or distal enhancers have a much broader impact on ovarian function than the direct genomic effects of androgens. Third, androgen-induced decrease of H3K27me3 is mediated through (a) inhibiting the expression and activity of Enhancer of Zeste Homologue 2 (EZH2), a histone methyltransferase that promotes tri-methylation of K27 and (b) by inducing the expression of a histone demethylase called Jumonji domain containing protein-3 (JMJD3/KDM6B), responsible for removing the H3K27me3 mark. Androgens through the PI3K/Akt pathway, in a transcription-independent fashion, increase hypoxia-inducible factor 1 alpha (HIF1α) protein levels, which in turn induce JMJD3 expression. Furthermore, proof of concept studies involving in vivo knockdown of Ar in the ovary and ovarian (granulosa) cell-specific Ar knockout mouse model show that ARs regulate the expression of key ovarian genes through modulation of H3K27me3.

Hypoxia-Driven Effects in Cancer: Characterization, Mechanisms, and Therapeutic Implications

Hypoxia, a common feature of solid tumors, greatly hinders the efficacy of conventional cancer treatments such as chemo-, radio-, and immunotherapy. The depletion of oxygen in proliferating and advanced tumors causes an array of genetic, transcriptional, and metabolic adaptations that promote survival, metastasis, and a clinically malignant phenotype. At the nexus of these interconnected pathways are hypoxia-inducible factors (HIFs) which orchestrate transcriptional responses under hypoxia. The following review summarizes current literature regarding effects of hypoxia on DNA repair, metastasis, epithelial-to-mesenchymal transition, the cancer stem cell phenotype, and therapy resistance. We also discuss mechanisms and pathways, such as HIF signaling, mitochondrial dynamics, exosomes, and the unfolded protein response, that contribute to hypoxia-induced phenotypic changes. Finally, novel therapeutics that target the hypoxic tumor microenvironment or interfere with hypoxia-induced pathways are reviewed.

Downregulation of long non-coding RNA LOC101928477 correlates with tumor progression by regulating the epithelial-mesenchymal transition in esophageal squamous cell carcinoma

Background

Esophageal squamous cell carcinoma (ESCC) is one of the deadliest malignancies. There is a growing body of evidence showing that long non‐coding RNAs (lncRNAs) play critical roles in ESCC oncogenesis. The present study aimed to explore the role of LOC101928477, a newly discovered lncRNA, in the development and metastasis of ESCC.

Methods

In this study, real‐time PCR, western blotting, cell counting kit‐8 (CCK‐8), flow cytometry, colony formation, wound healing, transwell migration/invasion assay, immunofluorescence, and immunohistochemistry were used. We also applied an in situ xenograft mouse model and a lung metastasis mouse model to verify our findings.

Results

We determined that LOC101928477 expression was inhibited in ESCC tissue and ESCC cell lines when compared with controls. Moreover, forced expression of LOC101928477 effectively inhibited ESCC cell proliferation, colony formation, migration, and invasion via suppression of epithelial‐mesenchymal transition (EMT). Furthermore, LOC101928477 overexpression inhibited in situ tumor growth and lung metastasis in a mouse model.

Conclusions

Together, our results suggested that LOC101928477 could be a novel suppressor gene involved in ESCC progression.

The Transcription Factor C/EBPβ Promotes HFL-1 Cell Migration, Proliferation, and Inflammation by Activating lncRNA HAS2-AS1 in Hypoxia

Objective

Recent studies were widely concerned about the role of lncRNAs in hypoxic pulmonary hypertension (HPH). HAS2 was found significantly highly expressed in HPH, but the antisense of HAS2 (HAS2-AS1) has not been explored in HPH, providing a new potential therapeutic target of HPH.

Methods

In this study, human fetal lung fibroblast-1 (HFL-1) cells were cultured under hypoxia conditions to stimulate the pathological process of HPH. Transwell and wound-healing assays were used to detect HFL-1 cell migration, and CCK 8 assay was used to detect cell proliferation. The upstream transcription factor of HAS2-AS1 was predicted by JASPAR website, and the binding site between C/EBPβ and HAS2-AS1 was predicted by JASPAR, too. In order to verify the association between C/EBPβ and the HAS2 promoter region, we used chromatin immunoprecipitation (ChIP) and dual luciferase reporter gene detection, western blot to detect the expression of inflammation-related proteins, and qRT-PCR to detect the expression of HAS2-AS1 and HAS2. Idiopathic pulmonary fibrosis (IPF) with HPH patient microarray data was downloaded from the GEO database and analyzed by R software.

Results

Our study showed that HAS2-AS1 and C/EBPβ were highly expressed in hypoxic HFL-1 cells, and the knockdown of HAS2-AS1 expression could inhibit the proliferation, migration, and inflammatory response of HFL-1 cells. C/EBPβ binds to the promoter region of HAS2-AS1 and has a positive regulation effect on the transcription of HAS2-AS1. Furthermore, C/EBPβ can regulate the proliferation, migration, and inflammatory response of HFL-1 cells through HAS2-AS1.

Conclusion

This study suggested that C/EBPβ could upregulate HAS2-AS1 expression and induce HFL-1 cell proliferation, migration, and inflammation response.

Long Noncoding RNAs in the Metastasis of Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is a common malignant tumor worldwide. Metastasis is the main cause of the death of OSCC patients. Long noncoding RNAs (lncRNAs), one of the key factors affecting OSCC metastasis, are a subtype of RNA with a length of more than 200 nucleotides that has little or no coding potential. In recent years, the important role played by lncRNAs in biological processes, such as chromatin modification, transcription regulation, RNA stability regulation, and mRNA translation, has been gradually revealed. More and more studies have shown that lncRNAs can regulate the metastasis of various tumors including OSCC at epigenetic, transcriptional, and post-transcriptional levels. In this review, we mainly discussed the role and possible mechanisms of lncRNAs in OSCC metastasis. Most lncRNAs act as oncogenes and only a few lncRNAs have been shown to inhibit OSCC metastasis. Besides, we briefly introduced the research status of cancer-associated fibroblasts-related lncRNAs in OSCC metastasis. Finally, we discussed the research prospects of lncRNAs-mediated crosstalk between OSCC cells and the tumor microenvironment in OSCC metastasis, especially the potential research value of exosomes and lymphangiogenesis. In general, lncRNAs are expected to be used for screening, treatment, and prognosis monitoring of OSCC metastasis, but more work is still required to better understand the biological function of lncRNAs.

Cell Energy Metabolism and Hyaluronan Synthesis

Hyaluronan (HA) is a linear glycosaminoglycan (GAG) of extracellular matrix (ECM) synthesized by three hyaluronan synthases (HASes) at the plasma membrane using uridine diphosphate (UDP)-glucuronic acid (UDP-GlcUA) and UDP-N-acetylglucosamine (UDP-GlcNAc) as substrates. The production of HA is mainly regulated by hyaluronan synthase 2 (HAS2), that can be controlled at different levels, from epigenetics to transcriptional and post-translational modifications. HA biosynthesis is an energy-consuming process and, along with HA catabolism, is strongly connected to the maintenance of metabolic homeostasis. The cytoplasmic pool of UDP-sugars is critical for HA synthesis. UDP-GlcNAc is an important nutrient sensor and serves as donor substrate for the O-GlcNAcylation of many cytosolic proteins, including HAS2. This post-translational modification stabilizes HAS2 in the membrane and increases HA production. Conversely, HAS2 can be phosphorylated by AMP activated protein kinase (AMPK), a master metabolic regulator activated by low ATP/AMP ratios, which inhibits HA secretion. Similarly, HAS2 expression and the deposition of HA within the pericellular coat are inhibited by sirtuin 1 (SIRT1), another important energetic sensor, confirming the tight connection between nutrients availability and HA metabolism.

Long Noncoding RNA Expression Profiling Reveals Upregulation of Uroplakin 1A and Uroplakin 1A Antisense RNA 1 under Hypoxic Conditions in Lung Cancer Cells

Hypoxia plays important roles in cancer progression by inducing angiogenesis, metastasis, and drug resistance. However, the effects of hypoxia on long noncoding RNA (lncRNA) expression have not been clarified. Herein, we evaluated alterations in lncRNA expression in lung cancer cells under hypoxic conditions using lncRNA microarray analyses. Among 40,173 lncRNAs, 211 and 113 lncRNAs were up- and downregulated, respectively, in both A549 and NCI-H460 cells. Uroplakin 1A (UPK1A) and UPK1A-antisense RNA 1 (AS1), which showed the highest upregulation under hypoxic conditions, were selected to investigate the effects of UPK1AAS1 on the expression of UPK1A and the mechanisms of hypoxia-inducible expression. Following transfection of cells with small interfering RNA (siRNA) targeting hypoxiainducible factor 1α (HIF-1α), the hypoxia-induced expression of UPK1A and UPK1A-AS1 was significantly reduced, indicating that HIF-1α played important roles in the hypoxiainduced expression of these targets. After transfection of cells with UPK1A siRNA, UPK1A and UPK1A-AS1 levels were reduced. Moreover, transfection of cells with UPK1A-AS1 siRNA downregulated both UPK1A-AS1 and UPK1A. RNase protection assays demonstrated that UPK1A and UPK1A-AS1 formed a duplex; thus, transfection with UPK1A-AS1 siRNA decreased the RNA stability of UPK1A. Overall, these results indicated that UPK1A and UPK1A-AS1 expression increased under hypoxic conditions in a HIF-1α-dependent manner and that formation of a UPK1A/UPK1A-AS1 duplex affected RNA stability, enabling each molecule to regulate the expression of the other.

Interplay of long non-coding RNAs and HIF-1α: A new dimension to understanding hypoxia-regulated tumor growth and metastasis

Hypoxia is a feature of the solid tumor microenvironment that is associated with poor clinical outcomes in multiple tumor types. Hypoxia-induced factor-1 alpha (HIF-1α) is a master regulator of hypoxic adaption, has been demonstrated to modulate hypoxic gene expression profiling and signaling transduction networks, and is thus a potential therapeutic target. Despite hypoxic response signaling having being extensively studied, the involvement of long non-coding RNAs (lncRNAs) in the hypoxic response has become a new focus of attention. Emerging evidence has documented complex interactions between HIF-1α and lncRNAs, which contribute to the acquisition of multiple hallmarks of cancer. In this review, we focus on recent advances in the study of hypoxia and HIF-1α-regulated lncRNAs, and summarize the molecular mechanisms and functional outcomes of the interplay between lncRNAs and HIF-1α, which may provide important insights into cancer diagnosis and prognosis, enabling better control of cancer.

Construction of a Nomogram Based on a Hypoxia-Related lncRNA Signature to Improve the Prediction of Gastric Cancer Prognosis

Background

Gastric cancer is one of the most common malignant tumors and has a poor prognosis. Hypoxia is related to the poor prognosis of cancer patients. We searched for hypoxia-related long non-coding RNAs (lncRNAs) to predict both overall survival (OS) and disease-free survival (DFS) of gastric cancer patients.

Methods

We obtained hypoxia-related lncRNA expression profiles and clinical follow-up data of patients with gastric cancer from The Cancer Genome Atlas and the Molecular Signatures Database. The patients were randomly divided into a training group, test group and combined group. The hypoxia-related prognostic signature was constructed by Lasso regression and Cox regression models, the prognoses in different groups were compared by Kaplan-Meier (K-M) analysis, and the accuracy of the prognostic model was assessed by receiver operating characteristic (ROC) analysis.

Results

A hypoxia-related prognostic signature comprising 10 lncRNAs was constructed to predict both OS and DFS in gastric cancer. In the training, test and combined groups, patients were divided into high- and low-risk groups according to the formula. Kaplan-Meier analysis showed that patients in the high-risk group have poor prognoses, and the difference was significant in the subgroup analyses. Receiver operating characteristic analysis revealed that the predictive power of the model prediction is more accurate than that of standard benchmarks. The signature differed across Helicobacter pylori (Hp) status and T stages. Multivariate Cox analysis showed that the signature is an independent risk factor for both OS and DFS. A clinically predictive nomogram combining the lncRNA signature and clinical features was constructed; the nomogram accurately predicted both OS and DFS and had high clinical application value. Weighted correlation network analysis combined with enrichment analysis showed that the primary pathways were the PI3K-Akt, JAK-STAT, and IL-17 signaling pathways. The target genes NOX4, COL8A1, and CHST1 were associated with poor prognosis in the Gene Expression Profiling Interactive Analysis, Gene Expression Omnibus, and K-M Plotter databases.

Conclusions

Our 10-lncRNA prognostic signature and nomogram are accurate, reliable tools for predicting both OS and DFS in gastric cancer.

HAS2-AS1 Acts as a Molecular Sponge for miR-137 and Promotes the Invasion and Migration of Glioma Cells by Targeting EZH2

This study aims to explore the molecular mechanism by which HAS2-AS1 acts as a ceRNA to promote the invasion and migration of glioma cells, which will provide a novel potential target for the targeted therapy of glioma. Gene expression profiles and corresponding clinical data were accessed from the TCGA_LGG and TCGA_GBM databases and then differential analysis was conducted using the "edgeR" package. miRDB, miRTarBase and TargetScan databases were employed to predict target genes and sequentially a ceRNA network was constructed. Quantitative real-time PCR was performed to detect gene expression in glioma cells. Transwell assay was operated to assess cell migratory and invasive abilities. Western blot was conducted to evaluate the protein expression. Dual-luciferase reporter assay and RNA immunoprecipitation experiment were performed to validate the targeting relationship between genes. HAS2-AS1 was markedly upregulated in glioma, and the overall survival time of patients with high HAS2-AS1 expression was significantly shorter than that of patients with low one. Silencing HAS2-AS1 inhibited the migration and invasion of glioma cells, while overexpressing HAS2-AS1 produced opposite results. miR-137 was validated as a direct target of and negatively regulated by HAS2-AS1. Further exploration of the downstream target gene indicated that EZH2 competed with HAS2-AS1 to interact with miR-137. Suppressing miR-137 or up-regulating EZH2 reversed the impact of HAS2-AS1 knockdown on glioma cell invasion and migration. HAS2-AS1 regulates EZH2 by sponging miR-137 for the migratory and invasive abilities of glioma cells, which provides a new idea for exploring metastasis mechanism of glioma.

Hypoxia-inducible long noncoding RNA NPSR1-AS1 promotes the proliferation and glycolysis of hepatocellular carcinoma cells by regulating the MAPK/ERK pathway

Hepatocellular carcinoma (HCC), which accounts for approximately 90% of primary liver cancer, is commonly treated with surgical resection. However, most patients lose the opportunity to receive this therapeutic strategy due to delayed diagnosis and rapid tumor progression. Long noncoding RNAs (lncRNAs) have been demonstrated to play essential roles in the initiation and progression of HCC. However, the function of the novel lncRNA neuropeptide S receptor 1 antisense RNA 1 (NPSR1-AS1) in HCC and its potential mechanism, is unclear. Here, our microarray data revealed NPSR1-AS1 as a novel hypoxia-responsive lncRNA in HCC cells. Interestingly, hypoxia-inducible factor-1α (HIF-1α) knockdown abolished hypoxia-induced NPSR1-AS1 expression in HCC cells. NPSR1-AS1 expression was upregulated in HCC tissues and cell lines. Next, the ectopic expression of NPSR1-AS1 facilitated the proliferation and glycolysis of HCC cells. In contrast, NPSR1-AS1 silencing repressed HCC cell proliferation and glycolysis. Mechanistically, NPSR1-AS1 overexpression increased the levels of p-ERK1/2 and pyruvate kinase M2 (PKM2) in HCC cells. NPSR1-AS1 knockdown abrogated hypoxia-induced the activation of the MAPK/ERK pathway in HCC cells. Importantly, NPSR1-AS1 depletion partially reversed hypoxia-induced proliferation and glycolysis of HCC cells in vitro. In conclusion, hypoxia-inducible NPSR1-AS1 promotes the proliferation and glycolysis of HCC cells, possibly by regulating the MAPK/ERK pathway, suggesting an underlying therapeutic strategy for HCC.

Natural antisense transcripts in the biological hallmarks of cancer: powerful regulators hidden in the dark

Natural antisense transcripts (NATs), which are transcribed from opposite strands of DNA with partial or complete overlap, affect multiple stages of gene expression, from epigenetic to post-translational modifications. NATs are dysregulated in various types of cancer, and an increasing number of studies focusing on NATs as pivotal regulators of the hallmarks of cancer and as promising candidates for cancer therapy are just beginning to unravel the mystery. Here, we summarize the existing knowledge on NATs to highlight their underlying mechanisms of functions in cancer biology, discuss their potential roles in therapeutic application, and explore future research directions.

Long noncoding RNAs in cancer immunity: a new avenue in drug discovery

The central role of the nonprotein-coding portion of the genome, such as long noncoding (lnc)RNAs is emerging as a hidden player manipulating the immune system in cancer. lncRNAs, in association with their interacting partners, regulate the expression of various immune system genes, which are perturbed during cancer. The tissue-specific expression of lncRNAs and their importance in cellular proliferation, the tumor microenvironment (TME), epithelial-mesenchymal transition (EMT), and modulation of the cells of the innate and adaptive immune system have novel therapeutic implications in establishing lncRNAs as biomarkers and targets to overcome cancer-associated immunosuppression. In this review, we establish and strengthen the link between lncRNAs and cancer immunity.

Long noncoding RNA PVT1 promotes tumor cell proliferation, invasion, migration and inhibits apoptosis in oral squamous cell carcinoma by regulating miR‑150‑5p/GLUT‑1

Oral squamous cell carcinoma (OSCC) is a cancer with high morbidity and mortality. Research has demonstrated that long non-coding RNAs (lncRNAs) are critical for tumor initiation and development. In the present study, we aimed to ascertain the functions and potential mechanisms of lncRNA plasmacytoma variant translocation 1 (PVT1) in OSCC. Firstly, we found that the expression of PVT1 was increased in human OSCC tumor tissues and it was related to reduced survival of the patients. Furthermore, miR-150-5p expression was downregulated in OSCC tumor tissues and it was negatively related with PVT1. Moreover, GLUT-1 protein expression was upregulated in human OSCC tumor tissues. In addition, cell proliferation capacity was measured by CCK-8 assay and cell invasion and migration were measured by Transwell assay. PVT1 overexpression promoted cell proliferation, invasion and migration, while these effects were abrogated by PVT1 downregulation. In addition, luciferase gene reporter assay verified the miR-150-5p directly binds with PVT1, which regulates the biological functions of OSCC. Additionally, luciferase gene reporter assay confirmed that GLUT-1 was a target for miR-150-5p. The promotion of cell proliferation, invasion and migration in LV-PVT1-transfected cells was eliminated following miR-150-5p overexpression. Finally, in vivo nude mouse xenograft model further verified that PVT1 knockdown inhibited tumor growth, formation, invasion and migration. According to the results, PVT1 is increased in human OSCC tumor tissues, and is related to the poor prognosis of human OSCC patients. We uncovered a previously unappreciated PVT1/miR-150-5p/GLUT-1 signaling axis that promotes cell proliferation, invasion, migration and inhibits apoptosis in OSCC cell lines and in vivo, which suggests that this axis could be a target for the treatment of OSCC.

Comprehensive analysis of a long non-coding RNA-associated competing endogenous RNA network in glioma

Long non-coding RNAs (lncRNAs) can act as competing endogenous RNAs (ceRNAs), interacting with microRNAs (miRNAs) and playing an important role in tumor progression. However, the role of lncRNA-mediated ceRNAs in glioma remains largely unknown. The present study aimed to identify novel lncRNAs and their associated function in glioma. RNA sequencing and corresponding clinical data from patients with glioma were obtained from The Cancer Genome Atlas. A total of 598 glioma tissues and 5 normal brain tissues were analyzed in the present study. The differentially expressed (DE) lncRNAs, mRNAs and miRNAs were identified using R packages and were used to construct a ceRNA network. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were performed to investigate the biological functions of the DEmRNAs. Kaplan-Meier curve analysis was performed to investigate the association between DElncRNA expression and patient outcome. A total of 752 DElncRNAs, 2,079 DEmRNAs and 113 DEmiRNAs were identified between glioma and normal tissues. A lncRNA-miRNA-mRNA ceRNA network consisting of 61 lncRNAs, 12 miRNAs and 92 mRNAs was constructed. Survival analysis indicated that 36 DElncRNAs, 72 DEmRNAs and 3 DEmiRNAs were associated with overall survival in patients with glioma. The present study identified novel lncRNAs associated with survival prognosis and may facilitate further investigation of lncRNA-mediated ceRNA regulatory mechanisms in glioma.

Involvement of hyaluronan in the adaptive changes of the rat small intestine neuromuscular function after ischemia/reperfusion injury

Intestinal ischemia/reperfusion (I/R) injury has severe consequences on myenteric neurons, which can be irreversibly compromised resulting in slowing of transit and hindered food digestion. Myenteric neurons synthesize hyaluronan (HA) to form a well-structured perineuronal net, which undergoes derangement when myenteric ganglia homeostasis is perturbed, i.e. during inflammation. In this study we evaluated HA involvement in rat small intestine myenteric plexus after in vivo I/R injury induced by clamping a branch of the superior mesenteric artery for 60 min, followed by 24 h of reperfusion. In some experiments, 4-methylumbelliferone (4-MU, 25 mg/kg), a HA synthesis inhibitor, was intraperitoneally administered to normal (CTR), sham-operated (SH) and I/R animals for 24 h. In longitudinal muscle myenteric plexus (LMMP) whole-mount preparations, HA binding protein staining as well as HA levels were significantly higher in the I/R group, and were reduced after 4-MU treatment. HA synthase 1 and 2 (HAS1 and HAS2) labelled myenteric neurons and mRNA levels in LMMPs increased in the I/R group with respect to CTR, and were reduced by 4-MU. The efficiency of the gastrointestinal transit was significantly reduced in I/R and 4-MU-treated I/R groups with respect to CTR and SH groups. In the 4-MU-treated I/R group gastric emptying was reduced with respect to the CTR, SH and I/R groups. Carbachol (CCh) and electrical field (EFS, 0.1–40 Hz) stimulated contractions and EFS-induced (10 Hz) NANC relaxations were reduced in the I/R group with respect to both CTR and SH groups. After I/R, 4-MU treatment increased EFS contractions towards control values, but did not affect CCh-induced contractions. NANC on-relaxations after I/R were not influenced by 4-MU treatment. Main alterations in the neurochemical coding of both excitatory (tachykinergic) and inhibitory pathways (iNOS, VIPergic) were also observed after I/R, and were influenced by 4-MU administration. Overall, our data suggest that, after an intestinal I/R damage, changes of HA homeostasis in specific myenteric neuron populations may influence the efficiency of the gastrointestinal transit. We cannot exclude that modulation of HA synthesis in these conditions may ameliorate derangement of the enteric motor function preventing, at least in part, the development of dysmotility.

Upregulation of long non-coding RNA FOXD2-AS1 promotes progression and predicts poor prognosis in tongue squamous cell carcinoma

BACKGROUND

Accumulating evidences suggest that lncRNA FOXD2-AS1 plays an important role in tumor progression, however, its function in tongue squamous cell carcinoma (TSCC) remains unknown. This research aims to investigate the function and mechanism of FOXD2-AS1 in the modulation of tongue squamous cell carcinoma progression.

METHODS

Expression of FOXD2-AS1 was detected in TSCC tissues and TCGA data. Receiver operating characteristic curves (ROCs) analysis and bioinformatic analysis of TCGA data were performed to investigate the role of FOXD2-AS1 in TSCC prognosis. After siRNA-mediated downregulation of FOXD2-AS1, wound healing assay, Transwell migration and invasion assays, and MTS proliferation assay were conducted to explore the effects that FOXD2-AS1 exerted on SCC-9 and CAL-27 cell lines. Western blotting was performed to detect the downstream protein changes.

RESULTS

Compared to the normal tissues and samples, FOXD2-AS1 significantly highly expressed in TSCC tissues and in TSCC samples of TCGA data, and high expression of FOXD2-AS1 was associated with lymphatic metastasis and poor TNM stages. ROC analysis and bioinformatic analysis of TCGA data further suggested that high expression of FOXD2-AS1 was associated with TSCC poor prognosis. Downregulation of FOXD2-AS1 inhibited the migration and invasion of SCC-9 and CAL-27 cell lines. Western blotting showed that the expression of p-p44 and p-p65 downregulated after FOXD2-AS1 knockdown.

CONCLUSION

High expression of FOXD2-AS1 promotes TSCC progression through modulating NF-kB and ERK MAPK signaling pathways and is associated with TSCC poor prognosis, it could be a novel therapeutic target and prognostic biomarker for TSCC.

Long non‑coding RNAs are novel players in oral inflammatory disorders, potentially premalignant oral epithelial lesions and oral squamous cell carcinoma (Review)

In recent years, a large number of studies have shown that the abnormal expression of long non‑coding (lnc)RNAs can lead to a variety of different diseases, including inflammatory disorders, cardiovascular disease, nervous system diseases, and cancers. Recent research has demonstrated the biological characteristics of lncRNAs and the important functions of lncRNAs in oral inflammation, precancerous lesions and cancers. The present review aims to explore and discuss the potential roles of candidate lncRNAs in oral diseases by summarizing multiple lncRNA profiles in diseased and healthy oral tissues to determine the altered lncRNA signatures. In addition, to highlight the exact regulatory mechanism of lncRNAs in oral inflammatory disorders, potentially premalignant oral epithelial lesions and oral squamous cell carcinoma. The detection of lncRNAs in oral samples has the potential to be used as a diagnostic and an early detection tool for oral diseases. Furthermore, lncRNAs are promising future therapeutic targets in oral diseases, and research in this field may expand in the future.

Signaling in and out: long-noncoding RNAs in tumor hypoxia

Over the past few years, long non-coding RNAs (lncRNAs) are recognized as key regulators of gene expression at chromatin, transcriptional and posttranscriptional level with pivotal roles in various biological and pathological processes, including cancer. Hypoxia, a common feature of the tumor microenvironment, profoundly affects gene expression and is tightly associated with cancer progression. Upon tumor hypoxia, the central regulator HIF (hypoxia-inducible factor) is upregulated and orchestrates transcription reprogramming, contributing to aggressive phenotypes in numerous cancers. Not surprisingly, lncRNAs are also transcriptional targets of HIF and serve as effectors of hypoxia response. Indeed, the number of hypoxia-associated lncRNAs (HALs) identified has risen sharply, illustrating the expanding roles of lncRNAs in hypoxia signaling cascade and responses. Moreover, through extra-cellular vesicles, lncRNAs could transmit hypoxia responses between cancer cells and the associated microenvironment. Notably, the aberrantly expressed cellular or exosomal HALs can serve as potential prognostic markers and therapeutic targets. In this review, we provide an update of the current knowledge about the expression, involvement and potential clinical impact of lncRNAs in tumor hypoxia, with special focus on their unique molecular regulation of HIF cascade and hypoxia-induced malignant progression.

LncRNA HOTAIR promotes the invasion and metastasis of oral squamous cell carcinoma through metastasis-associated gene 2

Despite therapeutic advancements, there has been little improvement in the survival status of patients with oral squamous cell carcinoma (OSCC). HOX antisense intergenic RNA (HOTAIR) has been shown to be dysregulated in several cancer types. However, the roles of HOTAIR in OSCC remain largely unknown. In this study, we investigated the association of HOTAIR expression with clinicopathological features in OSCC patients and the crucial roles of HOTAIR in the modulation of tumor progression. Our results showed that HOTAIR was highly expressed both in OSCC tissue samples and cell lines compared with corresponding normal oral mucosa tissues and human oral keratinocytes. Its overexpression was positively correlated with TNM (tumor-node-metastases) stage, histological grade, and regional lymph node metastasis. The knockdown of HOTAIR by short hairpin RNA significantly decreased the migration, invasion, and epithelial-mesenchymal transition of OSCC cells in vitro. Moreover, there was a negative correlation between HOTAIR and microRNA-326 expression in OSCC tissue samples and cell lines. Luciferase reporter and loss-of-function assays revealed that HOTAIR acted as a competitive endogenous RNA effectively sponging miR-326, thereby regulating the derepression of metastasis-associated gene 2 (MTA2). Finally, the expression and clinical significance of MTA2 were analyzed in another cohort of OSCC tissue samples. High MTA2 expression was significantly correlated with clinicopathological features of advanced OSCC and poor prognosis for patients with OSCC. Collectively, HOTAIR overexpression promoted the progression of OSCC. The HOTAIR-miR-326-MTA2 axis may contribute to a better understanding of OSCC pathogenesis and be a potential therapeutic target for OSCC.

Sirtuin 1 reduces hyaluronan synthase 2 expression by inhibiting nuclear translocation of NF-κB and expression of the long-noncoding RNA HAS2-AS1

Hyaluronan (HA) is one of the most prevalent glycosaminoglycans of the vascular extracellular matrix (ECM). Abnormal HA accumulation within blood vessel walls is associated with tissue inflammation and is prominent in most vascular pathological conditions such as atherosclerosis and restenosis. Hyaluronan synthase 2 (HAS2) is the main hyaluronan synthase enzyme involved in HA synthesis and uses cytosolic UDP-glucuronic acid and UDP-GlcNAc as substrates. The synthesis of UDP-glucuronic acid can alter the NAD⁺/NADH ratio via the enzyme UDP-glucose dehydrogenase, which oxidizes the alcohol group at C6 to the COO^- group. Here, we show that HAS2 expression can be modulated by sirtuin 1 (SIRT1), the master metabolic sensor of the cell, belonging to the class of NAD⁺-dependent deacetylases. Our results revealed the following. 1) Treatments of human aortic smooth muscle cells (AoSMCs) with SIRT1 activators (SRT1720 and resveratrol) inhibit both HAS2 expression and accumulation of pericellular HA coats. 2) Tumor necrosis factor α (TNFα) induced HA-mediated monocyte adhesion and AoSMC migration, whereas SIRT1 activation prevented immune cell recruitment and cell motility by reducing the expression levels of the receptor for HA-mediated motility, RHAMM, and the HA-binding protein TNF-stimulated gene 6 protein (TSG6). 3) SIRT1 activation prevented nuclear translocation of NF-κB (p65), which, in turn, reduced the levels of HAS2-AS1, a long-noncoding RNA that epigenetically controls HAS2 mRNA expression. In conclusion, we demonstrate that both HAS2 expression and HA accumulation by AoSMCs are down-regulated by the metabolic sensor SIRT1.

Hyaluronan in the Tumor Microenvironment

The extracellular matrix is part of the microenvironment and its functions are associated with the physical and chemical properties of the tissue. Among the extracellular components, the glycosaminoglycan hyaluronan is a key component, defining both the physical and biochemical characteristics of the healthy matrices. The hyaluronan metabolism is strictly regulated in physiological conditions, but in the tumoral tissues, its expression, size and binding proteins interaction are dysregulated. Hyaluronan from the tumor microenvironment promotes tumor cell proliferation, invasion, immune evasion, stemness alterations as well as drug resistance. This chapter describes data regarding novel concepts of hyaluronan functions in the tumor. Additionally, we discuss potential clinical applications of targeting HA metabolism in cancer therapy.

Long Non-coding RNA LOXL1-AS1 Drives Breast Cancer Invasion and Metastasis by Antagonizing miR-708-5p Expression and Activity

LOXL1-AS1, a recently characterized long non-coding RNA (lncRNA), has been reported to modulate tumor progression in several types of cancer. However, the expression and role of LOXL1-AS1 in breast cancer remain unclear. In this study, we sought to identify novel lncRNA regulators engaged in breast cancer metastasis. To this end, we examined 42 cancer-related lncRNAs between MCF7 (with low metastatic potential) and MDA-MB-231 (with high metastatic potential) cells. These lncRNAs have been found to affect the invasiveness of several cancer types, but they are still undefined in breast cancer. Among the 42 candidates, LOXL1-AS1 is significantly increased in MDA-MB-231 cells relative to MCF7 cells. We also show that LOXL1-AS1 is upregulated in breast cancer tissues and cells compared to noncancerous counterparts. Increased LOXL1-AS1 expression is correlated with tumor stage and lymph node metastasis in breast cancer patients. Biologically, overexpression of LOXL1-AS1 enhances and knockdown of LOXL1-AS1 suppresses breast cancer cell migration and invasion. In vivo studies demonstrate that depletion of LOXL1-AS1 inhibits breast cancer metastasis. Mechanistically, LOXL1-AS1 sponges miR-708-5p to increase nuclear factor κB (NF-κB) activity. LOXL1-AS1 can also interact with EZH2 protein to enhance EZH2-mediated transcriptional repression of miR-708-5p. Rescue experiments indicate that co-expression of miR-708-5p attenuates LOXL1-AS1-induced invasiveness in breast cancer. In addition, there is a negative correlation between LOXL1-AS1 and miR-708-5p expression in breast cancer specimens. Overall, LOXL1-AS1 upregulation facilitates breast cancer invasion and metastasis by blocking miR-708-5p expression and activity. LOXL1-AS1 serves as a potential therapeutic target for breast cancer treatment.

Long Non-coding RNA JHDM1D-AS1 Interacts with DHX15 Protein to Enhance Non-Small-Cell Lung Cancer Growth and Metastasis

JHDM1D antisense 1 (JHDM1D-AS1), a long non-coding RNA (lncRNA), has been shown to promote pancreatic cancer growth by inducing an angiogenic response. However, its biological and clinical significance in non-small-cell lung cancer (NSCLC) is still unclear. In this study, we examined the expression and prognostic significance of JHDM1D-AS1 in NSCLC. The effects of JHDM1D-AS1 knockdown or overexpression on NSCLC growth and metastasis were investigated. We show that JHDM1D-AS1 is upregulated in NSCLC relative to adjacent normal lung tissues. High JHDM1D-AS1 expression is significantly correlated with advanced tumor, node, and metastasis (TNM) stage and lymph node metastasis. JHDM1D-AS1 expression serves as an independent prognostic factor for overall survival of patients with NSCLC. Functionally, JHDM1D-AS1 knockdown inhibits NSCLC cell aggressiveness both in vitro and in vivo, which is rescued by ectopic expression of JHDM1D-AS1. JHDM1D-AS1 binding stabilizes DHX15 protein in NSCLC cells. DHX15 overexpression enhances NSCLC cell proliferation and invasion, whereas knockdown of DHX15 exerts opposite effects. JHDM1D-AS1-mediated aggressive phenotype is impaired when DHX15 is silenced. Ectopic expression of DHX15 restores the defects in proliferation and invasion of JHDM1D-AS1-depleted NSCLC cells. Collectively, the interaction between JHDM1D-AS1 and DHX15 accounts for NSCLC growth and metastasis. This work provides potential additional therapeutic targets for treatment of NSCLC.

Targeting Cellular Metabolism Modulates Head and Neck Oncogenesis

Considering the great energy and biomass demand for cell survival, cancer cells exhibit unique metabolic signatures compared to normal cells. Head and neck squamous cell carcinoma (HNSCC) is one of the most prevalent neoplasms worldwide. Recent findings have shown that environmental challenges, as well as intrinsic metabolic manipulations, could modulate HNSCC experimentally and serve as clinic prognostic indicators, suggesting that a better understanding of dynamic metabolic changes during HNSCC development could be of great benefit for developing adjuvant anti-cancer schemes other than conventional therapies. However, the following questions are still poorly understood: (i) how does metabolic reprogramming occur during HNSCC development? (ii) how does the tumorous milieu contribute to HNSCC tumourigenesis? and (iii) at the molecular level, how do various metabolic cues interact with each other to control the oncogenicity and therapeutic sensitivity of HNSCC? In this review article, the regulatory roles of different metabolic pathways in HNSCC and its microenvironment in controlling the malignancy are therefore discussed in the hope of providing a systemic overview regarding what we knew and how cancer metabolism could be translated for the development of anti-cancer therapeutic reagents.

Long noncoding RNA HAS2-AS1 promotes tumor progression in glioblastoma via functioning as a competing endogenous RNA

Glioblastoma multiforme (GBM) is a refractory tumor with poor prognosis and requires more effective treatment regimens. It has been confirmed that long noncoding RNAs (lncRNAs) substantially regulate various human disease including GBM. However, the biological roles and its underlying molecular mechanisms still need to be further investigated. In this study, the biological function and potential molecular mechanism of lncHAS2-AS1 in GBM were explored. It was discovered that HAS2-AS1 was elevated in glioma tissues and correlated with the prognosis of patients with glioma. Reduction of HAS2-AS1 suppressed the migration and invasion in vitro and in vivo. The transcription factor STAT1 could raise HAS2-AS1 by binding to its promoter region. Besides, HAS2-AS1 could adjust PRPS1 via sponging miR-608 in a direct manner. On the whole, the results of this study evidence that HAS2-AS1 is an oncogene and a potential therapeutic target for GBM.

Long Non-Coding RNA Expression Profile Associated with Malignant Progression of Oral Submucous Fibrosis

Oral submucous fibrosis (OSF) as one of the premalignant disorders endures a series of histopathological stages to invasive oral squamous cell carcinoma (OSCC) eventually. However, the role of long non-coding RNA (lncRNA) expression in OSF malignant progression still remains poorly understood. Through RNA-sequencing normal mucous, OSF and OSCC tissues, we found 687 lncRNA transcripts significantly and differentially expressed during OSF progression, including 231 upregulated lncRNAs and 456 downregulated lncRNAs, indicating that lncRNAs are involved in the regulation of different stages of OSF development. Further functional enrichment analysis showed these differentially expressed lncRNAs participated in inflammation signaling, Wnt signaling, angiogenesis, CCKR signaling, integrin signaling, PDGF signaling, p53 signaling, and EGF receptor (EGFR) signaling pathways, which contribute to inflammatory and fibroelastic pathogenetic changes of OSF and further malignant progression. Five novel lncRNAs were differentially expressed during OSF progression with varied expression levels, indicating the importance of these lncRNAs in OSF malignant development. Moreover, some lncRNAs have been previously identified to be associated with OSCC pathogenesis, including HCG22, RP11-397A16.1, LINC00271, CTD-3179P9.1, and ZNF667-AS1. Thus, our study firstly comprehensively elucidated lncRNAs expression profile of malignant procession from OSF premalignant lesion to OSCC, which will enlighten our understanding of the importance of lncRNA involved in OSF malignant development.