Inhibition of long non-coding RNA TUG1 on gastric cancer cell transference and invasion through regulating and controlling the expression of miR-144/c-Met axis

High Expression of EIF4G2 Mediated by the TUG1/Hsa-miR-26a-5p Axis Is Associated with Poor Prognosis and Immune Infiltration of Gastric Cancer

Objective

Eukaryotic translation initiation factor 4 gamma 2 (EIF4G2) is involved in the occurrence and development of various tumors. However, the effect of EIF4G2 in gastric cancer (GC) has not been fully explored. The purpose of this study was to explore the function and mechanism of EIF4G2 in GC.

Methods

The Tumor Immune Estimation Resource 2.0 database was used to analyze EIF4G2 expression in various cancers and the relationship between EIF4G2 expression and tumor-infiltrating immune cells. Gene Expression Profiling Interactive Analysis was utilized to assess the EIF4G2 expression level and its effect on survival in GC. UALCAN was conducted to analyze EIF4G2 expression in various subgroups of GC. The Kaplan-Meier plotter was employed for survival analysis. Receiver operator characteristic (ROC) curve analysis was applied to evaluate the diagnostic role of EIF4G2 in GC. LinkedOmics was used to identify the co-expressed genes and Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathways. The Tumor-Immune System Interaction database was employed to analyze the correlation between EIF4G2 expression and tumor-infiltrating lymphocytes. The starBase web platform was used to predict the upstream microRNAs and long noncoding RNAs.

Results

EIF4G2 expression was upregulated in GC tissues compared to normal controls. High expression of EIF4G2 indicated poor prognosis in GC. ROC analysis revealed that EIF4G2 had good diagnostic ability to distinguish GC from normal tissues. Immune infiltration analysis indicated that EIF4G2 expression may be involved in the modulation of tumor immune infiltration in GC. Finally, we determined that the Taurine Upregulated 1 (TUG1)/hsa-miR-26a-5p/EIF4G2 axis was the most likely regulatory pathway involved in GC development.

Conclusions

EIF4G2 was upregulated in GC and elevated expression of EIF4G2 indicated unfavorable prognosis. Moreover, EIF4G2 expression may be involved in the regulation of tumor immune cell infiltration. The TUG1/hsa-miR-26a-5p axis is a likely upstream regulatory mechanism of EIF4G2 in GC. EIF4G2 may thus serve as a prognosis biomarker and present a new therapeutic target.

Long non-coding RNA DLGAP1-AS1 promotes the progression of gastric cancer via miR-515-5p/MARK4 axis

Long non-coding RNA (lncRNA) is an essential regulator of carcinogenesis and cancer progression. In the study, we explored the role of lncRNA DLGAP1-AS1 in gastric cancer (GC). qRT-PCR was carried out to detect DLGAP1-AS1 expression in GC tissues and cell lines. CCK-8 assay, EdU assay, and transwell experiments were employed to detect the malignant biological behaviors of GC cells with DLGAP1-AS1 knockdown or overexpression. Bioinformatics and dual-luciferase report assay were used to confirm the binding relationship between DLGAP1-AS1 and miR-515-5p. MARK4 expression was detected by western blot after DLGAP1-AS1/miR-515-5p was selectively regulated. DLGAP1-AS1 was up-regulated in GC tissues and cell lines, and its high expression was closely associated with larger tumor size, higher TNM stage, and lymph node metastasis. Furthermore, DLGAP1-AS1 overexpression enhanced cell proliferation, migration, and invasion, and miR-515-5p could reverse these effects. DLGAP1-AS1 participated in the regulation of the MARK4 signaling pathway by targeting miR-515-5p. DLGAP1-AS1 promoted GC progression through miR-515-5p/MARK4 signaling pathway.

Recent advances in the regulation of ABCA1 and ABCG1 by lncRNAs

Coronary heart disease (CHD) with atherosclerosis is the leading cause of death worldwide. ABCA1 and ABCG1 promote cholesterol efflux to suppress foam cell generation and reduce atherosclerosis development. Long noncoding RNAs (lncRNAs) are emerging as a unique group of RNA transcripts that longer than 200 nucleotides and have no protein-coding potential. Many studies have found that lncRNAs regulate cholesterol efflux to influence atherosclerosis development. ABCA1 is regulated by different lncRNAs, including MeXis, GAS5, TUG1, MEG3, MALAT1, Lnc-HC, RP5-833A20.1, LOXL1-AS1, CHROME, DAPK1-IT1, SIRT1 AS lncRNA, DYNLRB2-2, DANCR, LeXis, LOC286367, and LncOR13C9. ABCG1 is also regulated by different lncRNAs, including TUG1, GAS5, RP5-833A20.1, DYNLRB2-2, ENST00000602558.1, and AC096664.3. Thus, various lncRNAs are associated with the roles of ABCA1 and ABCG1 on cholesterol efflux in atherosclerosis regulation. However, some lncRNAs play dual roles in ABCA1 expression and atherosclerosis, and the functions of some lncRNAs in atherosclerosis have not been investigated in vivo. In this article, we review the roles of lncRNAs in atherosclerosis and focus on new insights into lncRNAs associated with the roles of ABCA1 and ABCG1 on cholesterol efflux and the potential of these lncRNAs as novel therapeutic targets in atherosclerosis.

Relationship between long non-coding RNA TUG1 and prognosis of patients with gastric carcinoma: A protocol for systematic review and meta-analysis

BACKGROUND

Long non-coding RNA (lncRNA) can predict the prognosis of patients with various cancers. The relationship between lncRNA taurine upregulated gene 1 (TUG1) and the prognosis of patients with gastric carcinoma still needs to be further explored. Therefore, this study attempted to explore the relationship between TUG1 and the prognosis of patients suffering from gastric carcinoma.

METHODS

The database was retrieved from China National Knowledge Infrastructure (CNKI), Chinese Biomedical literature Database (CBM), Chinese Scientific and Journal Database (VIP), Wan Fang database, PubMed, and EMBASE. Hazard ratios (HRs) and its 95% confidence interval (CIs) were applied to assess the prognostic effects of TUG1 on overall survival (OS). RevMan 5.3 software was adopted to perform meta-analysis.

RESULTS

The results of this meta-analysis would be submitted to peer-reviewed journals for publication.

CONCLUSION

This review provided a comprehensive overview of the relationship between TUG1 and the prognosis of patients with gastric carcinoma, and offered recommendations for clinical practices or guidelines.

Pathophysiological Functions of the lncRNA TUG1

BACKGROUND

Long non-coding RNAs (lncRNAs) with little or no coding capacity are associated with a plethora of cellular functions, participating in various biological processes. Cumulative study of lncRNA provides explanations to the physiological and pathological processes and new perspectives to the diagnosis, prevention, and treatment of some clinical diseases. Long non-coding RNA taurine-upregulated gene 1(TUG1) is one of the first identified lncRNAs associated with human disease, which actively involved in various physiological processes, including regulating genes at epigenetics, transcription, post-transcription, translation, and posttranslation. The aim of this review was to explore the molecular mechanism of TUG1 in various types of human diseases.

METHODS

In this review, we summarized and analyzed the latest findings related to the physiologic and pathophysiological processes of TUG1 in human diseases. The related studies were retrieved and selected the last six years of research articles in PubMed with lncRNA and TUG1 as keywords.

RESULTS

TUG1 is a valuable lncRNA that its dysregulated expression and regulating the biological processes were found in a variety of human diseases. TUG1 is found to exhibit aberrant expression in a variety of malignancies. Dysregulation of TUG1 has been shown to contribute to proliferation, migration, cell cycle changes, inhibited apoptosis, and drug resistance of cancer cells, which revealed an oncogenic role for this lncRNA, but some reports have shown downregulation of TUG1 in lung cancer samples compared with noncancerous samples. In addition, the molecular and biological functions of TUG1 in physiology and disease (relevant to endocrinology, metabolism, immunology, neurobiology) have also been highlighted. Finally, we discuss the limitations and tremendous diagnostic/therapeutic potential of TUG1 in cancer and other diseases.

CONCLUSION

Long non-coding RNA-TUG1 likely served as useful disease biomarkers or therapy targets and effectively applied in different kinds of diseases, such as human cancer and cardiovascular diseases.

Role of taurine, its haloamines and its lncRNA TUG1 in both inflammation and cancer progression. On the road to therapeutics? (Review)

For one century, taurine is considered as an end product of sulfur metabolism. In this review, we discuss the beneficial effect of taurine, its haloamines and taurine upregulated gene 1 (TUG1) long non‑coding RNA (lncRNA) in both cancer and inflammation. We outline how taurine or its haloamines (N‑Bromotaurine or N‑Chlorotaurine) can induce robust and efficient responses against inflammatory diseases, providing insight into their molecular mechanisms. We also provide information about the use of taurine as a therapeutic approach to cancer. Taurine can be combined with other chemotherapeutic drugs, not only mediating durable responses in various malignancies, but also circumventing the limitations met from chemotherapeutic drugs, thus improving the therapeutic outcome. Interestingly, the lncRNA TUG1 is regarded as a promising therapeutic approach, which can overcome acquired resistance of cancer cells to selected strategies. In this regard, we can translate basic knowledge about taurine and its TUG1 lncRNA into potential therapeutic options directed against specific oncogenic signaling targets, thereby bridging the gap between bench and bedside.

MiR-144: A New Possible Therapeutic Target and Diagnostic/Prognostic Tool in Cancers

MicroRNAs (miRNAs) are small and non-coding RNAs that display aberrant expression in the tissue and plasma of cancer patients when tested in comparison to healthy individuals. In past decades, research data proposed that miRNAs could be diagnostic and prognostic biomarkers in cancer patients. It has been confirmed that miRNAs can act either as oncogenes by silencing tumor inhibitors or as tumor suppressors by targeting oncoproteins. MiR-144s are located in the chromosomal region 17q11.2, which is subject to significant damage in many types of cancers. In this review, we assess the involvement of miR-144s in several cancer types by illustrating the possible target genes that are related to each cancer, and we also briefly describe the clinical applications of miR-144s as a diagnostic and prognostic tool in cancers.

MicroRNAs and Long Non-coding RNAs in c-Met-Regulated Cancers

MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are components of many signaling pathways associated with tumor aggressiveness and cancer metastasis. Some lncRNAs are classified as competitive endogenous RNAs (ceRNAs) that bind to specific miRNAs to prevent interaction with target mRNAs. Studies have shown that the hepatocyte growth factor/mesenchymal-epithelial transition factor (HGF/c-Met) pathway is involved in physiological and pathological processes such as cell growth, angiogenesis, and embryogenesis. Overexpression of c-Met can lead to sustained activation of downstream signals, resulting in carcinogenesis, metastasis, and resistance to targeted therapies. In this review, we evaluated the effects of anti-oncogenic and oncogenic non-coding RNAs (ncRNAs) on c-Met, and the interactions among lncRNAs, miRNAs, and c-Met in cancer using clinical and tissue chromatin immunoprecipition (ChIP) analysis data. We summarized current knowledge of the mechanisms and effects of the lncRNAs/miR-34a/c-Met axis in various tumor types, and evaluated the potential therapeutic value of lncRNAs and/or miRNAs targeted to c-Met on drug-resistance. Furthermore, we discussed the functions of lncRNAs and miRNAs in c-Met-related carcinogenesis and potential therapeutic strategies.

Crosstalk Mechanisms Between HGF/c-Met Axis and ncRNAs in Malignancy

Several lines of evidence have confirmed the magnitude of crosstalk between HGF/c-Met axis (hepatocyte growth factor and its high-affinity receptor c-mesenchymal-epithelial transition factor) and non-coding RNAs (ncRNAs) in tumorigenesis. Through activating canonical or non-canonical signaling pathways, the HGF/c-Met axis mediates a range of oncogenic processes such as cell proliferation, invasion, apoptosis, and angiogenesis and is increasingly becoming a promising target for cancer therapy. Meanwhile, ncRNAs are a cluster of functional RNA molecules that perform their biological roles at the RNA level and are essential regulators of gene expression. The expression of ncRNAs is cell/tissue/tumor-specific, which makes them excellent candidates for cancer research. Many studies have revealed that ncRNAs play a crucial role in cancer initiation and progression by regulating different downstream genes or signal transduction pathways, including HGF/c-Met axis. In this review, we discuss the regulatory association between ncRNAs and the HGF/c-Met axis by providing a comprehensive understanding of their potential mechanisms and roles in cancer development. These findings could reveal their possible clinical applications as biomarkers for therapeutic interventions.

Clinical significance of reduced expression of lncRNA TUG1 in the peripheral blood of systemic lupus erythematosus patients

OBJECTIVE

To investigate the expression and clinical significance of long non-coding RNA taurine up-regulated gene 1 (lncRNA TUG1) in the peripheral blood of systemic lupus erythematosus (SLE) patients.

METHODS

With the peripheral blood mononuclear cells (PBMCs: T-cells, B-cells and monocytes) collected from SLE patients and healthy controls, TUG1 expression was determined to identify the correlation with the clinicopathological features of SLE patients. Thereby, the diagnostic value of TUG1 expression in diagnosis of SLE was evaluated by receiver operating characteristic (ROC) curve analysis.

RESULTS

As compared to healthy controls, SLE patients manifested a lower expression of TUG1 in PBMCs, which was further decreased in SLE patients with lupus nephritis (P < .05). The lowest level of TUG1 was found in monocytes, rather than T-cells or B-cells (P < .05). Negative correlations were identified between TUG1 levels and SLE Disease Activity Index score (r = -.904, P < .001), erythrocyte sedimentation rate (r = -.779, P < .001), disease duration (r = -.503, P < .001) and 24-hour urinary protein (r = -.807, P < .001). Complement C3 levels were positively associated with TUG1 expression (r = .817, P < .001). In addition, the area under the ROC curve of diagnostic efficiency for SLE based on TUG1 was 0.982, and 0.930 for SLE with lupus nephritis.

CONCLUSIONS

The levels of lncRNA TUG1 was markedly lower in the SLE patients, which was more obvious in SLE patients with lupus nephritis, and thus, it could be a promising clinical diagnostic tool for SLE patients or SLE patients with lupus nephritis.

LncRNA FTX Promotes Proliferation and Invasion of Gastric Cancer via miR-144/ZFX Axis

BACKGROUND

Long non-coding RNAs are important regulators in cancer cell tumorigenesis. We have demonstrated in a prior study that lncRNA FTX is dysregulated in gastric cancer (GC). In this study, we aim to report gastric cancer-related lncRNA FTX as a main regulator in GC development and progression.

METHODS

In vitro and in vivo assays of FTX alterations have been performed to reveal a complex integrated phenotype affecting cell growth, migration, and invasion. lncRNA FTX expression levels in gastric cancer cells and normal cells were measured by RT-PCR. Luciferase reporter assays, Western blotting, and many immune, microscopy technologies were utilized to investigate the expressions of FTX- related proteins and RNAs. The functional role of FTX in cell growth, migration, and invasion were observed in vitro and in vivo.

RESULTS

We explored the underlying mechanisms of FTX in GC development, and the microRNAs' relationship with FTX. We found that FTX promoted cell proliferation, migration, and invasion, as well as tumor growth, and this effect could latterly be attenuated by miR-144. ZFX attenuated the effects of FTX/miR-144 axis by sponging with miR-144.

CONCLUSION

In summary, the above results support a model in which the FTX/miR-144/ZFX act as important effectors in GC tumorigenesis and progression, indicating new therapeutic methods in GC.

Long non-coding RNA signature in gastric cancer

Gastric cancer as a common human malignancy has been associated with aberrant expressions of several coding and non-coding genes. Long non-coding RNAs (lncRNAs) as regulators of gene expressions at different genomic, transcriptomic and post-transcriptomic levels are among putative biomarkers and therapeutic targets in gastric cancer. In the present study, we have searched available literature and listed lncRNAs that are involved in the pathogenesis of gastric cancer. In addition, we discuss associations between expressions of these lncRNAs and tumoral features or risk factors for gastric cancer. Based on the established role of lncRNAs in regulation of genomic stability, cell cycle, apoptosis, angiogenesis and other aspects of cell physiology, the potential of these transcripts as therapeutic targets in gastric cancer should be evaluated in future studies.

Long non-coding RNA TUSC7 suppresses osteosarcoma by targeting miR-211

Long non-coding RNAs (lncRNAs) play a critical role in regulating cancer progression and metastasis. LncRNA tumor suppressor candidate 7 (TUSC-7) was shown to be a tumor suppressor in osteosarcoma. However, the regulation mechanism of TUSC-7 in osteosarcoma is unknown. Bioinformatics analysis showed that TUSC7 specifically binds to miR-211. MiR-211 was up-regulated in osteosarcoma and negatively correlated with the expression of TUSC7. miR-211 expression was inhibited remarkably by TUSC7 overexpression and the reciprocal inhibition exists between TUSC7 and miR-211. RNA pull-down and luciferase reporter assays were used to validate the sequence-specific correlation between miR-211 and TUSC7. TUSC7 inhibited the proliferation, migration of osteosarcoma cells and promoted cellular apoptosis, which is largely mediated by miR-211. We conclude that the TUSC7 acted as a tumor suppressor gene, which is negatively regulated by miR-211. Our study could suggest a potentially novel therapeutic strategy against osteosarcoma.

Long non-coding RNAs in non-small cell lung cancer: functions and distinctions from other malignancies

Lung cancer leads to the most cancer-related death in the world. It was shown from the increasing evidences that long non-coding RNAs (lncRNAs) are emerging as molecules for diagnosis, prognosis and even therapy of lung cancer and other malignancies. The biological functions or involved signaling pathways of lncRNAs are always found to be inconsistent among different types of malignancies. However, no available literature has systemically summarized differences in the functions and underlying molecular mechanisms of lncRNAs between lung cancer and other cancers. In this review, the biological functions and molecular mechanisms of lncRNAs in lung cancer were introduced. Furthermore, their functional differences between lung cancer and other malignancies were discussed. Finally, their potential clinical applications in future lung cancer therapy were focused on.

Long non-coding RNAs and cell death following ischemic stroke

Stroke is a major cause of morbidity and mortality worldwide, and extensive efforts have focused on the improvement of therapeutic strategies to reduce cell death following ischemic stroke. Uncovering the cellular and molecular pathophysiological processes in ischemic stroke have been a top priority. Long noncoding RNAs (lncRNAs) are endogenous molecules that play key roles in the pathophysiology of cerebral ischemia, and involved in the neuronal cell death during ischemic stroke. In recent years, a bulk of aberrantly expressed lncRNAs have been screened out in ischemic stroke insulted animals. LncRNAs along with their targets could affect the genetic machinery at molecular levels, and exploring their functions and mechanisms may be a promising option for ischemic stroke treatment. In this review, we summarize the current knowledge for lncRNAs in ischemic stroke, focusing on the role of specific lncRNAs that may underlie cell death to find possible therapeutic targets.

Molecular mechanisms of TUG1 in the proliferation, apoptosis, migration and invasion of cancer cells

Long non-coding RNAs (lncRNAs) are RNA sequences >200 nucleotides in length that have no protein-coding capacity. lncRNAs serve key roles in multiple biological processes, such as tumorigenesis and tumor progression. Taurine upregulated 1 (TUG1) is a novel lncRNA that has been associated with human cancer. TUG1 has attracted increasing attention in recent years and has been documented to be abnormally expressed in different types of cancer. Numerous studies indicate that TUG1 may be significantly associated with tumor development and cell metabolism by regulating cell proliferation, invasion, metastasis, apoptosis, differentiation and drug resistance. TUG1 exerts its function via recruiting specific RNA-binding proteins, promoting target gene expression, influencing tumor angiogenesis and by functioning as a competing endogenous RNA (ceRNA). An increasing number of studies have demonstrated that ceRNAs serve a role in cancer development. TUG1 is considered to be a biomarker or a novel therapeutic target for the diagnosis and prognosis of different cancer types. The present review focuses on recent developments in the major underlying molecular mechanisms of TUG1 in cancer, including its role in cell proliferation, apoptosis, migration, invasion and drug resistance. Also discussed in the present review is the current knowledge regarding the regulation of TUG1.

Anticancer potential of TUG1 knockdown in cisplatin-resistant osteosarcoma through inhibition of MET/Akt signalling

Development of cisplatin (DDP)-resistance is a major challenge that largely limits the efficacy of chemotherapy for osteosarcoma. LncRNA Taurine up-regulated gene 1 (TUG1) is a recently identified oncogenic lncRNA that has been involved in chemo-resistance of various cancers. In this study, over-expression of TUG1 was found in two osteosarcoma cell lines resistant to DDP (Saos-2/DDP, MG-63/DDP). Knockdown of TUG1 inhibited the DDP-resistance and promoted the cytotoxicity and apoptosis induced by DDP in Saos-2/DDP and MG-63/DDP cells. TUG1 knockdown also markedly inhibited the expression level of MET and p-Akt. In conclusion, knockdown of TUG1 suppressed cell growth and increased apoptotic rate under DDP treatment possibly via regulating MET/Akt signalling pathway.

LncRNAs with miRNAs in regulation of gastric, liver, and colorectal cancers: updates in recent years

Long noncoding RNA (lncRNA) is a kind of RNAi molecule composed of hundreds to thousands of nucleotides. There are several major types of functional lncRNAs which participate in some important cellular pathways. LncRNA-RNA interaction controls mRNA translation and degradation or serves as a microRNA (miRNA) sponge for silencing. LncRNA-protein interaction regulates protein activity in transcriptional activation and silencing. LncRNA guide, decoy, and scaffold regulate transcription regulators of enhancer or repressor region of the coding genes for alteration of expression. LncRNA plays a role in cellular responses including the following activities: regulation of chromatin structural modification and gene expression for epigenetic and cell function control, promotion of hematopoiesis and maturation of immunity, cell programming in stem cell and somatic cell development, modulation of pathogen infection, switching glycolysis and lipid metabolism, and initiation of autoimmune diseases. LncRNA, together with miRNA, are considered the critical elements in cancer development. It has been demonstrated that tumorigenesis could be driven by homeostatic imbalance of lncRNA/miRNA/cancer regulatory factors resulting in biochemical and physiological alterations inside the cells. Cancer-driven lncRNAs with other cellular RNAs, epigenetic modulators, or protein effectors may change gene expression level and affect the viability, immortality, and motility of the cells that facilitate cancer cell cycle rearrangement, angiogenesis, proliferation, and metastasis. Molecular medicine will be the future trend for development. LncRNA/miRNA could be one of the potential candidates in this category. Continuous studies in lncRNA functional discrepancy between cancer cells and normal cells and regional and rational genetic differences of lncRNA profiles are critical for clinical research which is beneficial for clinical practice.

Taurine-upregulated gene 1: A functional long noncoding RNA in tumorigenesis

Taurine-upregulated gene 1 (TUG1) is a 7.1 kb long noncoding RNA (lncRNA) first recognized in 2005 as an important element for retinal development in rodents. Subsequently, this lncRNA has been shown to participate in oncogenic processes through alteration in chromatin structure, sponging microRNAs, and affecting the expression of some cancer-related pathways. While most of the studies have revealed an oncogenic role for this lncRNA, some reports have shown downregulation of TUG1 in lung cancer samples compared with noncancerous samples. In triple negative breast cancer samples, the expression of this lncRNA has been decreased. Besides, its expression has been higher in HER2-enriched and basal-like subtypes compared with luminal A. In the current review, we discuss the latest literature about the expression pattern and functional roles of TUG1 in diverse cancer types. In addition, its role in epithelial-mesenchymal transition and activation of Wnt/β-catenin pathway in human malignancies will be explored.

miR-144-3p facilitates nasopharyngeal carcinoma via crosstalk with PTEN

AIMS

This study aims to investigate the role of miR-144-3p and phosphatase and tensin homolog (PTEN) in nasopharyngeal carcinoma (NPC), along with their crosstalk with the phosphoinositide 3-kinase (PI3K)-protein kinase B (Akt) pathway.

METHODS

Quantitative reverse transcription polymerase chain reaction and western blot were used to measure the gene expression at the transcriptional and translational levels. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and colony formation assay were used to examine cell proliferation via standard protocol. Transwell assay was conducted to examine cell invasiveness. A flow cytometer was used to determine cell apoptosis. Dual-Luciferase Reporter Gene Assay (SLDL-100) was used to confirm the target relationship between miR-144-3p and PTEN. Xenografts were used to detect the in vivo effects of the molecules of interest.

RESULTS

miR-144-3p was significantly overexpressed, whereas PTEN was more underexpressed in tumor tissues than in adjacent tissues. miR-144-3p promoted the proliferation and invasion of NPC cells and inhibited apoptosis by directly targeting PTEN, which improves PI3K-Akt signaling. miR-144-3p forced epithelial-mesenchymal transition in NPC.

CONCLUSION

miR-144-3p promotes the progression of NPC by directly targeting PTEN via crosstalk with PI3K-Akt signaling.

Taurine-upregulated gene 1 contributes to cancers through sponging microRNA

Long non-coding RNAs (lncRNAs) are a class of RNAs whose transcripts are more than 200 nucleotides in length and lack protein-coding ability. Taurine-upregulated gene 1 (TUG1), a novel cancer-related lncRNA, has been documented to be abnormally expressed in various types of cancers and act as an oncogene or anti-oncogene. It has been considered previously that TUG1 is closely related to the cell proliferation, invasion, metastasis, and apoptosis of cancer. In recent years, it has been found that TUG1 acts as a microRNA (miRNA) sponge to indirectly regulate the expression of the miRNA target gene and dominates cancer progression in several types of cancers. However, TUG1 also binds to different miRNAs to produce diverse regulatory mechanisms in the same cancer. TUG1 is expected to be a biomarker and a new therapeutic target for the diagnosis and prognosis of certain cancers. In this review, we highlight the up-to-date original studies that focus on the role of TUG1 sponging miRNA in cancers and summarize the function of TUG1 in cancer progression. The novel TUG1-miRNA regulatory network is comprehensively and minutely included in this review. We hope that this review will help readers obtain a more detailed knowledge of the molecular mechanism by which TUG1 sponging miRNA plays its role in cancers, and provide some insights and directions for future cancer research.

TUG1 promotes prostate cancer progression by acting as a ceRNA of miR-26a

Previous studies have demonstrated that taurine-upregulated gene 1 (TUG1) was aberrantly expressed and involved in multiple types of cancer; however, the expression profile and potential role of TUG1 in prostate cancer (PCa) remains unclear. The aim of the present study was to evaluate the expression and function of TUG1 in PCa. In the present study, we analyzed TUG1 expression levels of PCa patients in tumor and adjacent normal tissue by real-time quantitative PCR. Knockdown of TUG1 by RNAi was performed to explore its roles in cell proliferation, migration, and invasion. Here we report, for the first time, that TUG1 promotes tumor cell migration, invasion, and proliferation in PCa by working in key aspects of biological behaviors. TUG1 could negatively regulate the expression of miR-26a in PCa cells. The bioinformatics prediction revealed putative miR-26a-binding sites within TUG1 transcripts. In conclusion, our study suggests that long non-coding RNA (lncRNA) TUG1 acts as a functional oncogene in PCa development.

LncRNA TUG1 interacting with miR-144 contributes to proliferation, migration and tumorigenesis through activating the JAK2/STAT3 pathway in hepatocellular carcinoma

Recently, it is reported that taurine upregulated gene 1 (TUG1) participates in the tumor progression by acting as a competing endogenous RNA (ceRNA) of miRNAs. Nonetheless, whether TUG1 could serve as a ceRNA of miR-144 in hepatocellular carcinoma (HCC) progression remains undefined. Here, our results indicated that there was a marked rise in TUG1 expression in HCC tissues and cells, and downregulation of TUG1 hindered proliferation and migration of HCC cells. Additionally, TUG1 was validated to act as a molecular sponge of miR-144. Furthermore, we found that TUG1 interacting with miR-144 contributed to proliferation and migration of HCC cells via activating the JAK2/STAT3 pathway in vitro. Moreover, TUG1 knockdown inhibited HCC tumor growth in vivo through upregulating miR-144 via inactivation of the JAK2/STAT3 pathway. In conclusion, TUG1 interacting with miR-144 contributed to proliferation, migration and tumorigenesis through activation of the JAK2/STAT3 pathway in HCC.

Prognostic role of lncRNA TUG1 for cancer outcome: Evidence from 840 cancer patients

LncRNA TUG1 has been demonstrated to be aberrantly expressed in several types of cancer and maybe serve as a prognostic marker for cancer patients. However, most individual studies have been limited by small sample sizes and controversial results. Therefore, this meta analysis was conducted to analyze available data to delineate the potential clinical application of lncRNA TUG1 on cancer prognosis, lymph node metastasis and tumor progression. Up to February 20, 2017, literature collections were conducted by comprehensive searching electronic databases, including Cochrane Library, PubMed, Embase, BioMed Central, Springer, ScienceDirect, ISI Web of Knowledge, together with three Chinese databases. The hazard ratios (HR) with 95% confidence interval (95% CI) were calculated to assess the strength of the association. Eight studies with a total of 840 cancer patients were included in the present meta analysis. The results indicated that elevated lncRNA TUG1 significantly predicted unfavorable overall survival (OS) (HR = 2.06, 95% CI: 1.23–3.45, P = 0.006), but failed to show incline to lymph node metastasis (HR: 1.16, 95% CI: 0.82–1.62, P = 0.40) and disease progression (III/IV vs. I/II: HR 1.16, 95% CI: 0.74–1.81, P = 0.52). In stratified analyses, a significantly unfavorable OS associated with elevated lncRNA TUG1 was observed in both bladder cancer (HR = 2.98, 95% CI: 1.84–4.83, P < 0.0001) and other system cancer (HR = 2.63, 95% CI: 1.42–4.87, P = 0.002), but not respiratory system cancer (HR = 0.93, 95% CI: 0.30–2.82, P = 0.895). The results indicated that increased lncRNA TUG1 was an independent prognostic biomarker for unfavorable OS but may not susceptible to lymph node metastasis and tumor progression in cancer patients.

Long non-coding RNAs in ischemic stroke

Stroke is one of the leading causes of mortality and disability worldwide. Uncovering the cellular and molecular pathophysiological processes in stroke have been a top priority. Long non-coding (lnc) RNAs play critical roles in different kinds of diseases. In recent years, a bulk of aberrantly expressed lncRNAs have been screened out in ischemic stroke patients or ischemia insulted animals using new technologies such as RNA-seq, deep sequencing, and microarrays. Nine specific lncRNAs, antisense non-coding RNA in the INK4 locus (ANRIL), metastasis-associate lung adenocarcinoma transcript 1 (MALAT1), N1LR, maternally expressed gene 3 (MEG3), H19, CaMK2D-associated transcript 1 (C2dat1), Fos downstream transcript (FosDT), small nucleolar RNA host gene 14 (SNHG14), and taurine-upregulated gene 1 (TUG1), were found increased in cerebral ischemic animals and/or oxygen-glucose deprived (OGD) cells. These lncRNAs were suggested to promote cell apoptosis, angiogenesis, inflammation, and cell death. Our Gene Ontology (GO) enrichment analysis predicted that MEG3, H19, and MALAT1 might also be related to functions such as neurogenesis, angiogenesis, and inflammation through mechanisms of gene regulation (DNA transcription, RNA folding, methylation, and gene imprinting). This knowledge may provide a better understanding of the functions and mechanisms of lncRNAs in ischemic stroke. Further elucidating the functions and mechanisms of these lncRNAs in biological systems under normal and pathological conditions may lead to opportunities for identifying biomarkers and novel therapeutic targets of ischemic stroke.

TPGLDA: Novel prediction of associations between lncRNAs and diseases via lncRNA-disease-gene tripartite graph

Accumulating evidences have indicated that lncRNAs play an important role in various human complex diseases. However, known disease-related lncRNAs are still comparatively small in number, and experimental identification is time-consuming and labor-intensive. Therefore, developing a useful computational method for inferring potential associations between lncRNAs and diseases has become a hot topic, which can significantly help people to explore complex human diseases at the molecular level and effectively advance the quality of disease diagnostics, therapy, prognosis and prevention. In this paper, we propose a novel prediction of lncRNA-disease associations via lncRNA-disease-gene tripartite graph (TPGLDA), which integrates gene-disease associations with lncRNA-disease associations. Compared to previous studies, TPGLDA can be used to better delineate the heterogeneity of coding-non-coding genes-disease association and can effectively identify potential lncRNA-disease associations. After implementing the leave-one-out cross validation, TPGLDA achieves an AUC value of 93.9% which demonstrates its good predictive performance. Moreover, the top 5 predicted rankings of lung cancer, hepatocellular carcinoma and ovarian cancer are manually confirmed by different relevant databases and literatures, affording convincing evidence of the good performance as well as potential value of TPGLDA in identifying potential lncRNA-disease associations. Matlab and R codes of TPGLDA can be found at following: https://github.com/USTC-HIlab/TPGLDA .

SNHG16/miR-140-5p axis promotes esophagus cancer cell proliferation, migration and EMT formation through regulating ZEB1

Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive malignancies. Long noncoding RNAs (lncRNAs) have been identified to be associated with many diseases including tumors, and involved in the regulation of a wide array of pathophysiological processes. Small nucleolar RNA host gene 16 (SNHG16), also known as noncoding RNA expressed in aggressive neuroblastoma, was newly identified as a potential oncogene in many cancers. However, its role in ESCC has not been investigated. In the current study, the level of SNHG16 in the ESCC tissues and cell lines was measured by quantitative real-time PCR (qRT-PCR). Then loss-of-function assays were performed to explore the biological effects of SNHG16 in ESCC cell. Based on the online database analysis tools, we uncovered that miR-140-5p could interact with SNHG16 and the level of miR-140-5p was inverse correlated with SNHG16 in ESCC specimens. Moreover, RIP, RNA pulldown system and dual luciferase reporter assay further provided evidence that SNHG16 directly targets miR-140-5p by binding with microRNA binding site harboring in the SNHG16 sequence. Furthermore, bioinformatics analysis revealed that ZEB1 is a target of miR-140-5p in ESCC. Collectively, our findings suggested that SNHG16 could act as an oncogenic lncRNA that promotes tumor progression through acting as an endogenous ‘sponge’ by competing with miR-140-5p, thereby regulating target ZEB1.

TUG1 mediates methotrexate resistance in colorectal cancer via miR-186/CPEB2 axis

Colorectal cancer (CRC) is a common malignancy, most of which remain unresponsive to chemotherapy. Methotrexate (MTX) is one of the earliest cytotoxic drugs and serves as an anti-metabolite and anti-folate chemotherapy for various types of cancer. However, MTX resistance prevents its clinical application in cancer therapy. Thereby, overcoming the drug resistance is an alternative strategy to maximize the efficacy of MTX therapies in clinics. Long non-coding RNAs (lncRNAs) have gained widespread attention in recent years. More and more evidences have shown that lncRNAs play regulatory roles in various biological activities and disease progression including drug resistance in cancer cells. Here, we observed lncRNA TUG1 was associated to the MTX resistant in colorectal cancer cells. Firstly, quantitative analysis indicated that TUG1 was significantly increased in tumors which were resistant to MTX treatment. TUG1 knockdown re-sensitized the MTX resistance in colorectal cancer cells, which were MTX-resistant colorectal cell line. Furthermore, bioinformatics analysis showed that miR-186 could directly bind to TUG1, suggesting TUG1 might worked as a ceRNA to sponge miR-186. Extensively, our study also showed that CPEB2 was the direct target of miR-186 in colorectal cancer cells. Taken together, our study suggests that lncRNA TUG1 mediates MTX resistance in colorectal cancer via miR-186/CPEB2 axis.

Long non-coding RNAs as an epigenetic regulator in human cancers

Recent studies have described the important multiple roles of long non‐coding RNAs (lncRNAs) during oncogenic transformation. Because the coding genome accounts for a small amount of total DNA, and many mutations leading to cancer occur in the non‐coding genome, it is plausible that the dysregulation of such non‐coding transcribes might also affect tumor phenotypes. Indeed, to date, lncRNAs have been reported to affect diverse biological processes through the regulation of mRNA stability, RNA splicing, chromatin structure, and miRNA‐mediated gene regulation by acting as miRNA sponges. Furthermore, accumulating studies have described the roles of lncRNAs in tumorigenesis; however, the precise mechanisms of many lncRNAs are still under investigation. Here, we discuss recently reported mechanistic insights into how lncRNAs regulate gene expression and contribute to tumorigenesis through interactions with other regulatory molecules. We especially highlight the role of taurine upregulated gene 1, which was recently reported to have biological functions related to gene regulation, and discuss the future clinical implications of lncRNAs in cancer treatments.

TUG1 promotes osteosarcoma tumorigenesis by upregulating EZH2 expression via miR-144-3p

lncRNA-TUG1 (Taurine upregulated 1) is up regulated and highly correlated with poor prognosis and disease status in osteosarcoma. TUG1 knockdown inhibits osteosarcoma cell proliferation, migration and invasion, and promotes apoptosis. However, its mechanism of action has not been well addressed. Growing evidence documented that lncRNA works as competing endogenous (ce)RNAs to modulate the expression and biological functions of miRNA. As a putative combining target of TUG1, miR-144-3p has been associated with the progress of osteosarcoma. To verify whether TUG1 functions through regulating miR-144-3p, the expression levels of TUG1 and miR-144-3p in osteosarcoma tissues and cell lines were determined. TUG1 was upregulated in osteosarcoma tissues and cell lines, and negatively correlated with miR-144-3p. TUG1 knockdown induced miR-144-3p expression in MG63 and U2OS cell lines. Results from dual luciferase reporter assay, RNA-binding protein immuno precipitation (RIP) and applied biotin-avidin pull-down system confirmed TUG1 regulated miR-144-3p expression through direct binding. EZH2, a verified target of miR-144-3p was upregulated in osteosarcoma tissues and negatively correlated with miR-144-3p. EZH2 was negatively regulated by miR-144-3p and positively regulated by TUG1. Gain-and loss-of-function experiments were performed to analyze the role of TUG1, miR-144-3p and EZH2 in the migration and EMT of osteosarcoma cells. EZH2 overexpression partly abolished TUG1 knockdown or miR-144-3p overexpression induced inhibition of migration and EMT in osteosarcoma cells. In addition, TUG1 knockdown represses the activation of Wnt/β-catenin pathway, which was reversed by EZH2 over expression. The activator of Wnt/β-catenin pathway LiCl could partially block the TUG1-knockdown induced osteosarcoma cell migration and EMT inhibition. In conclusion, our results showed that TUG1 plays an important role in osteosarcoma development through miRNA-144-3p/EZH2/Wnt/β-catenin pathway.

MiR-381 inhibits migration and invasion in human gastric carcinoma through downregulatedting SOX4

Aberrant expression of microRNAs (miRs) serves essential roles in the generation and progression of various types of human cancer. In the present study, the expression and biological functions of miR-381 in human gastric carcinoma (GC) were focused upon. The results of reverse transcription-quantitative polymerase chain reaction analysis revealed that the expression of miR-381 was significantly downregulated in GC tissue samples. Furthermore, low expression of miR-381 was identified to be associated with lymphatic metastasis and advanced tumor-node-metastasis stage (III+IV). Upregulation of miR-381 inhibited the migration and invasion of GC SGC-7901 cells through SRY-Box 4 (SOX4)-mediated epithelial-mesenchymal transition. Finally, long non-coding (lnc) RNA-taurine upregulatedted 1 (non-protein coding) (TUG1) was confirmed as a negatively regulator of miR-381 expression in SGC-7901 cells. Taken together, the results of the current study indicate that the downregulation of miR-381 by lncRNA-TUG1 promoted the metastasis of GC cells by inhibiting SOX4. Thus, targeting miR-381 may be a novel therapeutic option for the treatment of patients with GC.

Long Noncoding RNA Taurine-Upregulated Gene 1 Promotes Cell Proliferation and Invasion in Gastric Cancer via Negatively Modulating miRNA-145-5p

Long noncoding RNA (lncRNA) taurine-upregulated gene 1 (TUG1) is involved in the development and carcinogenesis of various tumors, suggesting the diagnostic potential of TUG1 in these cancers. However, the exact role of TUG1 and its underlying mechanism in gastric cancer (GC) remain unknown. In this study, the expression of TUG1 and miR-145-5p in GC cell lines and nonmalignant gastric epithelial cell lines was detected by qRT-PCR. BGC-823 and SGC-7901 cells were transfected with si-TUG1, pcDNA 3.1-TUG1, miR-145-5p mimics, or matched controls. The biological function of TUG1 and miR-145-5p in GC cell proliferation and invasion in vitro and tumor growth in vivo was investigated by MTT assay, Transwell invasion assay, and tumor xenograft experiments. The regulating relationship between TUG1 and miR-145-5 was confirmed by luciferase reporter assay. The results showed that TUG1 was significantly overexpressed and miR-145-5p was dramatically downregulated in GC cell lines. TUG1 knockdown strikingly inhibited cell proliferation and invasion in vitro and markedly suppressed tumor growth in vivo. Furthermore, TUG1 could directly bind to miR-145-5p and repress miR-145-5p expression. TUG1 overexpression significantly relieved the inhibition on GC cell proliferation and invasion in vitro and tumor growth in vivo, mediated by miR-145-5p overexpression. In conclusion, TUG1 promotes cell proliferation and invasion in GC via negatively modulating miRNA-145-5p, which undoubtedly contributes to understanding the mechanism of GC occurrence and development.

The significance of low levels of LINC RP1130-1 expression in human hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common neoplasms. Little progress has been made in the diagnosis and treatment of HCC and its prognosis remains poor. Studies have increasingly found that long non-coding RNA (lncRNA) is involved in the regulation of the occurrence and development of HCC. To investigate the diagnostic and prognostic value of lncRNA in HCC, the current study examined 25 lncRNAs with differing levels of expression (according to the fold change) in microarray databases. Expression of LINC RP1130-1 was found to be markedly down-regulated in 51 HCC tissues compared to matching adjacent non-tumor liver tissues. The pattern of expression and clinical significance of LINC RP1130-1 were examined in HCC. The area under the receiver operating characteristic (ROC) curve was 0.74 for LINC RP1130-1. The expression of LINC RP1130-1 was associated with clinical stage, the number of tumors, portal vein tumor thrombus (PVTT), and microvascular invasion (MVI). More importantly, patients with a low level of LINC RP1130-1 expression had a shorter recurrence-free survival (RFS) (n = 51, p < 0.05) than those with a high level of LINC RP1130-1 expression. Taken together, these findings indicate that a low level of LINC RP1130-1 expression in patients with HCC may be a powerful tumor biomarker, with potential clinical use in diagnosing and predicting the prognosis for patients with HCC.

Long non-coding RNA TUG1 contributes to tumorigenesis of human osteosarcoma by sponging miR-9-5p and regulating POU2F1 expression

Recent studies have shown that long non-coding RNAs (lncRNAs) have critical roles in tumorigenesis, including osteosarcoma. The lncRNA taurine-upregulated gene 1 (TUG1) was reported to be involved in the progression of osteosarcoma. Here, we investigated the role of TUG1 in osteosarcoma cells and the underlying mechanism. TUG1 expression was measured in osteosarcoma cell lines and human normal osteoblast cells by quantitative real-time PCR (qRT-PCR). The effects of TUG1 on osteosarcoma cells were studied by RNA interference in vitro and in vivo. The mechanism of competing endogenous RNA (ceRNA) was determined using bioinformatic analysis and luciferase assays. Our data showed that TUG1 knockdown inhibited cell proliferation and colony formation, and induced G0/G1 cell cycle arrest and apoptosis in vitro, and suppressed tumor growth in vivo. Besides, we found that TUG1 acted as an endogenous sponge to directly bind to miR-9-5p and downregulated miR-9-5p expression. Moreover, TUG1 overturned the effect of miR-9-5p on the proliferation, colony formation, cell cycle arrest, and apoptosis in osteosarcoma cells, which involved the derepression of POU class 2 homeobox 1 (POU2F1) expression. In conclusion, our study elucidated a novel TUG1/miR-9-5p/POU2F1 pathway, in which TUG1 acted as a ceRNA by sponging miR-9-5p, leading to downregulation of POU2F1 and facilitating the tumorigenesis of osteosarcoma. These findings may contribute to the lncRNA-targeted therapy for human osteosarcoma.