Prognostic role of long non-coding RNA TUG1 expression in various cancers: a meta-analysis

Long noncoding RNA TUG1 promotes malignant progression of osteosarcoma by enhancing ZBTB7C expression

BACKGROUND

Dysregulation of long non-coding RNAs (lncRNAs) is an important component of tumorigenesis. Aberrant expression of lncRNA taurine upregulated gene 1 (lncTUG1) has been reported in various tumors; however, its precise role and key targets critically involved in osteosarcoma (OS) progression remain unclear.

METHODS

The expression profiles of lncRNAs and their regulated miRNAs related to OS progression were assessed by bioinformatics analysis and confirmed by qRT-PCR of OS cells. The miRNA targets were identified by transcriptome sequencing and verified by luciferase reporter and RNA pull-down assays. Several in vivo and in vitro approaches, including CCK8 assay, western blot, qRT-PCR, lentiviral transduction and OS cell xenograft mouse model were established to validate the effects of lncTUG1 regulation of miRNA and the downstream target genes on OS cell growth, apoptosis and progression.

RESULTS

We found that lncTUG1 and miR-26a-5p were inversely up or down-regulated in OS cells, and siRNA-mediated lncTUG1 knockdown reversed the miR-26a-5p down-regulation and suppressed proliferation and enhanced apoptosis of OS cells. Further, we identified that an oncoprotein ZBTB7C was also upregulated in OS cells that were subjected to lncTUG1/miR-26a-5p regulation. More importantly, ZBTB7C knockdown reduced the ZBTB7C upregulation and ZBTB7C overexpression diminished the anti-OS effects of lncTUG1 knockdown in the OS xenograft model.

CONCLUSIONS

Our data suggest that lncTUG1 acts as a miR-26a-5p sponge and promotes OS progression via up-regulating ZBTB7C, and targeting lncTUG1 might be an effective strategy to treat OS.

Expression of oncolong noncoding RNA taurine-upregulated gene-1 in colon cancer: A clinical study supported by in silico analysis

Context

Recent studies confirmed that dysregulation of long noncoding RNAs (lncRNAs) is a potential contributor to the development and progression of colon cancer. However, the prognostic value of these RNA molecules remains controversial.

Aims

This study aimed to investigate the expression of taurine-upregulated gene-1 (TUG1) lncRNA in colon cancer and its clinical implications.

Subjects and Methods

A retrospective study on 47 formalin-fixed, paraffin-embedded samples of surgically resected primary colon cancer specimens was done. Total RNA purified from the colon cancer samples and noncancer adjacent tissue sections was quantified by real-time reverse transcription-polymerase chain reaction (qRT-PCR) to assess TUG1 relative expression levels normalized to GAPDH endogenous control. Also, in silico data analysis was applied.

Statistical Analysis Used

The relative expression levels were calculated using the LIVAK method. The survival rates were assessed using the Kaplan-Meier curves and the Cox proportional model. P < 0.05 was considered statistically significant.

Results

TUG1expression in the colon cancer specimens was significantly overexpressed (median = 21.50, interquartile range [IQR]: 7.0-209.2; P = 0.001) relative to the noncancerous tissues. In silico analysis confirmed TUG1 upregulation in colon carcinoma (median = 13.92, IQR: 13.5-1432). There were no significant associations between TUG1 expression and clinicopathological characteristics, such as the site, grade, stage, histopathological type, or the rates of lymphovascular invasion and relapse. Similarly, Kaplan-Meir and Cox multivariate regression analyses showed that TUG1 expression could not predict the overall survival and progression-free survival in colon cancer patients of our population.

Conclusions

This study confirms the overexpression of TUG1 lncRNA in colon cancer tissues. Larger sample size is warranted to further elucidate the specific role of TUG1 in colon cancer.

The pathogenic roles of lncRNA-Taurine upregulated 1 (TUG1) in colorectal cancer

Colorectal cancer (CRC) is a gastrointestinal tumor that develops from the colon, rectum, or appendix. The prognosis of CRC patients especially those with metastatic lesions remains unsatisfactory. Although various conventional methods have been used for the treatment of patients with CRC, the early detection and identification of molecular mechanisms associated with CRC is necessary. The scientific literature reports that altered expression of long non-coding RNAs (lncRNAs) contributed to the pathogenesis of CRC cells. LncRNA TUG1 was reported to target various miRNAs and signaling pathways to mediate CRC cell proliferation, migration, and metastasis. Therefore, TUG1 might be a potent predictive/prognostic biomarker for diagnosis of CRC.

Zooming in on Long Non-Coding RNAs in Ewing Sarcoma Pathogenesis

Ewing sarcoma (ES) is a rare aggressive cancer of bone and soft tissue that is mainly characterized by a reciprocal chromosomal translocation. As a result, about 90% of cases express the EWS-FLI1 fusion protein that has been shown to function as an aberrant transcription factor driving sarcomagenesis. ES is the second most common malignant bone tumor in children and young adults. Current treatment modalities include dose-intensified chemo- and radiotherapy, as well as surgery. Despite these strategies, patients who present with metastasis or relapse still have dismal prognosis, warranting a better understanding of treatment resistant-disease biology in order to generate better prognostic and therapeutic tools. Since the genomes of ES tumors are relatively quiet and stable, exploring the contributions of epigenetic mechanisms in the initiation and progression of the disease becomes inevitable. The search for novel biomarkers and potential therapeutic targets of cancer metastasis and chemotherapeutic drug resistance is increasingly focusing on long non-coding RNAs (lncRNAs). Recent advances in genome analysis by high throughput sequencing have immensely expanded and advanced our knowledge of lncRNAs. They are non-protein coding RNA species with multiple biological functions that have been shown to be dysregulated in many diseases and are emerging as crucial players in cancer development. Understanding the various roles of lncRNAs in tumorigenesis and metastasis would determine eclectic avenues to establish therapeutic and diagnostic targets. In ES, some lncRNAs have been implicated in cell proliferation, migration and invasion, features that make them suitable as relevant biomarkers and therapeutic targets. In this review, we comprehensively discuss known lncRNAs implicated in ES that could serve as potential biomarkers and therapeutic targets of the disease. Though some current reviews have discussed non-coding RNAs in ES, to our knowledge, this is the first review focusing exclusively on ES-associated lncRNAs.

LncRNA Taurine Upregulated Gene 1 as a Potential Biomarker in the Clinicopathology and Prognosis of Multiple Malignant Tumors: A Meta-Analysis

Background

The lncRNA taurine upregulated gene 1 (TUG1) is a recently identified potential biomarker in cancer. However, its prognostic role in various cancers is inconsistent among published data. We conducted this meta-analysis to comprehensively confirm the prognostic effect of TUG1 in malignant tumors.

Methods

We systemically analyzed the prognostic-predictive capacity of TUG1 through amplifying sample sizes and cancer types. STATA 12.0 was applied for this meta-analysis.

Results

A total of 57 eligible studies were included in our meta-analysis. The pooled results suggested that overexpression of TUG1 was significantly correlated with unfavorable overall survival (OS) (HR = 1.70, p < 0.001), shorter recurrence-free survival (RFS) (HR = 2.40, p ≤ 0.001), and shorter event-free survival (EFS) (HR = 1.88, p < 0.001) in patients with cancer. In the subgroup analysis by cancer type, elevated TUG1 expression was associated with poorer survival in patients with gastrointestinal cancer, urinary tumors, gynecological tumors, hematological tumors, and osteosarcoma. However, high expression of TUG1 in respiratory tumors indicated a better prognosis. There was no correlation between high TUG1 expression and OS in patients with head and neck neoplasms or melanoma. Additionally, overexpression of TUG1 was found to be correlated with low-grade tumor differentiation, advanced tumor stage, positive lymphatic metastasis, and positive distant metastasis.

Conclusions

High TUG1 expression correlates with poor prognosis and advanced clinicopathological features, verifying the prognostic-predictive capacity of TUG1 in tumors, especially in gastrointestinal cancer, urinary tumors, gynecological tumors, hematological tumors, and osteosarcoma. Meanwhile, the prognostic role of TUG1 in respiratory tumor may be opposite to other tumors.

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.

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.

The prognostic significance of long noncoding RNAs in bladder cancer: A meta-analysis

Introduction

Bladder cancer (BC) is one of the most common urologic malignancies and it is urgently needed to identify novel potential prognostic biomarkers for predicting prognosis and progression of patients with BC in clinical practice. Previous research has revealed that long noncoding RNAs (lncRNAs) played critical roles in BC, and may serve as novel potential prognostic biomarkers in patients with BC. Therefore, we conducted this meta-analysis to clarify the prognostic potential of lncRNAs in BC patients.

Methods

A comprehensive search was performed in PubMed, Web of Science, and China National Knowledge Infrastructure (CNKI). According to the predefined exclusion and inclusion criteria, a total of 9 recently published articles comprising 13 lncRNAs and 666 BC patients were included into this meta-analysis. We analyzed the hazard ratios (HRs) and 95% confidence intervals (CIs) to determine the relationship between lncRNAs expression and survival outcomes. We also analyzed the odds ratio (ORs) and 95% confidence intervals (CIs) to assess the association between lncRNAs expression and clinicopathological characteristics, including histological grade, gender, multifocality, tumor size, and tumor stage.

Results

Our results revealed that high lncRNAs expression was associated with shorter overall survival in Asian BC patients (pooled HR = 2.32, 95% CI: 1.35–4.00, P = 0.002, random-effect). High lncRNAs expression levels were significantly associated with histological grade (G2-G3 vs. G1: OR = 3.857, 95%CI: 1.293–11.502, P = 0.015, random-effect).

Conclusions

In summary, this meta-analysis has demonstrated that lncRNAs could be used as potential prognostic markers for BC and high lncRNAs expression could predict poor prognosis among Asian BC patients.

The prognostic value of long noncoding RNA Sox2ot expression in various cancers: A systematic review and meta-analysis

BACKGROUND

Several investigations have explored the prognostic value of long noncoding RNA Sox2 overlapping transcript (lncRNA Sox2ot) expression in human cancers, however, with inconsistent results. The aim of this study was to evaluate the prognostic role of lncRNA Sox2ot expression in various cancers.

METHODS

PubMed, Web of Science, Embase, and Cochrane Library were comprehensively searched to retrieve relevant studies. The relationships between lncRNA Sox2ot expression and prognostic parameters were detected, including overall survival (OS), tumor differentiation, clinical stage, distant metastasis, lymph node metastasis and so on.

RESULTS

A total of 10 studies involving 943 cancer patients were finally included into the study. High lncRNA Sox2ot expression was significantly related to shorter OS in cancers (HR = 2.06, 95%CI = 1.67-2.55, P < 0.01). The cancer patients with high lncRNA Sox2ot expression tended to have worse tumor differentiation (P = 0.04), advanced clinical stage (P < 0.01), earlier distant metastasis (P < 0.01), and earlier lymph node metastasis (P = 0.01) compared to those with low lncRNA Sox2ot expression. However, there was no distinct correlation between lncRNA Sox2ot expression and age (P = 0.87), gender (P = 0.48), tumor size (P = 0.08), or vascular invasion (P = 0.07).

CONCLUSION

High lncRNA Sox2ot expression was significantly associated with worse OS, advanced clinical stage, worse tumor differentiation, earlier distant metastasis, and earlier lymph node metastasis in various cancers. LncRNA Sox2ot expression might a promising prognostic factor in various cancers.