lncRNA Taurine-upregulated Gene 1 Research Articles

LncRNA TUG1 sponges miR-145 to promote cancer progression and regulate glutamine metabolism via Sirt3/GDH axis.

Long noncoding RNAs (lncRNAs) are important regulators in cancer progression. Deregulation of the lncRNA taurine upregulated gene 1 (TUG1) predicts poor prognosis and is implicated in the development of several cancers. In this study, we investigated the role of TUG1 in the pathogenesis of intrahepatic cholangiocarcinoma (ICC). We found that TUG1 is upregulated in ICC samples, which correlates with poor prognosis and adverse clinical pathological characteristics. Knockdown of TUG1 inhibited the proliferation, motility, and invasiveness of cultured ICC cells, and decreased tumor burden in a xenograft mouse model. When we explored the mechanisms underlying these effects, we found that TUG1 acts as an endogenous competing RNA (ceRNA) that ‘sponges’ miR-145, thereby preventing the degradation of Sirt3 mRNA and increasing expression of Sirt3 and GDH proteins. Accordingly, glutamine consumption, α-KG production, and ATP levels were dramatically decreased by TUG1 knockdown in ICC cells, and this effect was reversed by miR-145 inhibition. These findings indicate that the TUG1/miR-145/Sirt3/GDH regulatory network may provide a novel therapeutic strategy for treatment of ICC.

Downregulation of the long non-coding RNA TUG1 is associated with cell proliferation, migration, and invasion in breast cancer

Recent studies have identified many long non-coding RNAs (lncRNAs) with critical roles in various biological processes including tumorigenesis. Taurine-upregulated gene 1 (TUG1), is an lncRNA recently reported to be involved in the progression of several human cancers. This study aimed to investigate the clinical significance and biological functions of TUG1 in breast cancer. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to measure TUG1 expression in cells from breast cancer cell lines and in 58 matched pairs of breast cancer and normal tissue samples from patients with clinicopathological comparisons. Gain-and loss-of-function experiments were performed in vitro to investigate the biological role of TUG1. TUG1 expression was significantly downregulated in both breast cancer tissues and cell lines compared to controls, and low TUG1 expression was significantly correlated with mutant p53 expression (p=0.037) and lymph node metastasis (p=0.044). In vitro experiments revealed that TUG1 overexpression significantly suppressed cell proliferation by causing cell cycle arrest and inducing apoptosis in breast cancer cells, while TUG1 knockdown caused increased cell growth via promoting cell cycle progression and regulating the expression of cyclinD1 and CDK4. Further functional assays indicated that TUG1 overexpression significantly promoted cell migration and invasion while TUG1 knockdown had the opposite effects. Our findings indicate that the lncRNA TUG1 is a tumor suppressor in breast cancer, and may serve as a novel prognostic biomarker and potential therapeutic target for patients with breast cancer.

Prognostic value of long non-coding RNA TUG1 in various tumors.

Taurine up-regulated gene 1 (TUG1) is a long non-coding RNA (lncRNA), has been reported that be dysregulated in various tumors, involved in proliferation and apoptosis in a variety of tumor cells. To detect the clinical significance of TUG1 expression in tumor patients, we carried out current systematic review and meta-analysis investigating its relation with the prognosis and clinicopathological features of cancers. A total of 15 studies comprise 1560 patients were analyzed. The pooled results showed that no significant relationship between high TUG1 expression and overall survival (OS) (HR = 1.28, 95% CI: 0.96–1.69, P = 0.091) in various tumors. In the subgroup analysis by cancer type, elevated TUG1 expression was associated with poorer survival in cancer patients with high TUG1 expression subgroup but better survival in patients with low TUG1 expression subgroup. Over-expression of TUG1 associated with significantly unfavorable survival for bladder cancer (HR=2.67, 95% CI: 1.47–4.87, P = 0.001). Up-regulation of TUG1 correlated with distant metastasis (DM) (OR = 4.22, 95% CI: 2.66–6.70, P < 0.001) and tumor differentiation (OR = 2.45, 95% CI: 1.28–4.70, P = 0.007), but failed to show inline to gender (OR = 1.04, 95% CI: 0.77–1.42, P = 0.774), age (OR = 0.75, 95% CI: 0.51–1.10, P = 0.136), lymph node metastasis (LNM) (OR = 1.45, 95% CI: 0.85–2.50, P = 0.177), and TNM stage (OR = 0.55, 95% CI: 0.17–1.81, P = 0.326). The overall results suggest lncRNA TUG1 may be a useful prognostic biomarker in cancer patients.

An invitro study of the long non-coding RNA TUG1 in tongue squamous cell carcinoma.

This study sought to study the expression of the long non-coding RNA (lncRNA) taurine-upregulated gene 1 (TUG1) in tongue squamous cell carcinoma (TSCC) and reveal its possible function. qRT-PCR was used to evaluate 27 samples of fresh TSCC tissues and adjacent normal tongue tissues. siRNA technology was employed to downregulate TUG1 expression in CAL-27 and SCC-9 cell lines. The 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay was utilized to assess cell proliferation ability; apoptosis and cell-cycle phases were analysed via flow cytometry. qRT-PCR findings indicated that the lncRNA TUG1 was upregulated in TSCC tissues compared with adjacent normal tongue tissues (P<.05). After TUG1 expression was downregulated using siRNA technology, cell proliferation was significantly inhibited (P<.05), and the number of cells in S phase was reduced (P<.05). The lncRNA TUG1 may represent a potential oncogene in TSCC.

Long non-codingRNA (lncRNA) TUG1 and the prognosis of cancer: a meta-analysis.

Some studies assessed the association between lncRNA taurine-upregulated gene 1 (TUG1) and the survival in cancer. However, the results were inconclusive. Therefore, we performed a meta-analysis to determine this association. We used the following electronic databases to search for eligible literature: PubMed, Embase, Chinese National Knowledge Infrastructure (CNKI) and Wanfang. We used ORs and 95% CIs to measure the association between TUG1 and the survival of cancer. There was no significant association between TUG1 and OS of cancer (HR=1.26, 95% CI=0.97-1.64). In the subgroup analysis by cancer type, significant association could be find in osteosarcoma (HR=1.72, 95% CI=1.27-2.32) and digestive system's tumors (HR=1.66, 95% CI=1.04-2.66). In conclusion, this meta-analysis study indicated that TUG1 might associate with the OS of osteosarcoma and digestive system's tumors.

EZH2-mediated α-actin methylation needs lncRNA TUG1, and promotes the cortex cytoskeleton formation in VSMCs

Recent studies have revealed that long non-coding RNAs (lncRNAs) participate in vascular homeostasis and pathophysiological conditions development. But still very few literatures elucidate the regulatory mechanism of non-coding RNAs in this biological process. Here we identified lncRNA taurine up-regulated gene 1 (TUG1) in rat vascular smooth muscle cells (VSMCs), and got 4612bp nucleotide sequence. The expression level of TUG1 RNA was increased in synthetic VSMCs by real-time PCR analysis. Meanwhile, the expression of enhancer of zeste homolog 2 (EZH2) (TUG1 binding protein) increased in cytoplasm of VSMCs under the same conditions. Immunofluoresce analysis displayed the colocalization of EZH2 with α-actin in cytoplasm and F-actin in cell edge ruffles. This leads us to hypothesize the existence of cytoplasmic TUG1/EZH2/α-actin complex. Using RNA pull down assay, we found that TUG1 interacted with both EZH2 and α-actin. Disruption of TUG1 abolished the interaction of EZH2 with α-actin, and accelerated depolymerization of F-actin in VSMCs. Based on EZH2 methyltransferase activity and the potential methylation sites in α-actin structure, we revealed that α-actin was lysine-methylated. Furthermore, the methylation of α-actin was inhibited by knockdown of TUG1. In conclusion, these findings partly suggested that EZH2-mediated methylation of α-actin may be dependent on TUG1, and thereby promotes cortex F-actin polymerization in synthetic VSMCs.

Overexpression of Long Non-Coding RNA TUG1 Promotes Colon Cancer Progression.

BackgroundColon cancer is one of the most prevalent and deadly cancers worldwide. It is still necessary to further define the mechanisms and explore therapeutic targets of colon cancer. Dysregulation of long noncoding RNAs (lncRNAs) has been shown to be correlated with diverse biological processes, including tumorigenesis. This study aimed to characterize the biological mechanism of taurine-upregulated gene 1 (TUG1) in colon cancer.Material/MethodsqRT-PCR was used to analyze the expression level of TUG1 and p63 in 75 colon cancer tissues and the matched adjacent non-tumor tissue. In vitro, cultured colon cancer cell lines HCT-116 and LoVo were used as cell models. TUG1 and p63 were silenced via transferring siRNA into HCT-116 or LoVo. The effects of TUG1 were investigated by examining cell proliferation, apoptosis, and migration.ResultsAmong the 75 colon cancer cases, the expression of TUG1 was significantly higher in colon cancer tissues compared with the matched adjacent non-tumor tissue, while p63 expression was lower in the tumor tissue. In HCT-116 and LoVo, the expression of TUG1 was significantly increased by p63 siRNA transfection. Furthermore, down-regulation of TUG1 by siRNA significantly inhibited the cell proliferation and promoted colon cancer cell apoptosis. In addition, inhibition of TUG1 expression significantly blocked the cell migration ability of colon cancer cells.ConclusionsLncRNA TUG1 may serve as a potential oncogene for colon cancer. Overexpressed TUG1 may contribute to promoting cell proliferation and migration in colon cancer cells.

The long non-coding RNA TUG1 indicates a poor prognosis for colorectal cancer and promotes metastasis by affecting epithelial-mesenchymal transition.

BackgroundLong intergenic non-coding RNAs (lncRNAs) are a class of non-coding RNAs that are involved in gene expression regulation. Taurine up-regulated gene 1 (TUG1) is a cancer progression related lncRNA in some tumor oncogenesis; however, its role in colorectal cancer (CRC) remains unclear. In this study, we determined the expression patterns of TUG1 in CRC patients and explored its effect on CRC cell metastasis using cultured representative CRC cell lines.MethodsThe expression levels of TUG1 in 120 CRC patients and CRC cells were determined using quantitative real-time PCR. HDACs and epithelial-mesenchymal transition (EMT)-related gene expression were determined using western blot. CRC cell metastasis was assessed by colony formation, migration assay and invasion assay.ResultsOur data showed that the levels of TUG1 were upregulated in both CRC cell lines and primary CRC clinical samples. TUG1 upregulation was closely correlated with the survival time of CRC patients. Overexpression of TUG1 in CRC cells increased their colony formation, migration, and invasion invitro and promoted their metastatic potential in vivo, whereas knockdown of TUG1 inhibited the colony formation, migration, and invasion of CRC cells invitro. It is also worth pointing out that TUG1 activated EMT-related gene expression.ConclusionOur data suggest that tumor expression of lncRNA TUG1 plays a critical role in CRC metastasis. TUG1 may have potential roles as a biomarker and/or a therapeutic target in colorectal cancer.

Long non-coding RNA TUG1 is up-regulated in hepatocellular carcinoma and promotes cell growth and apoptosis by epigenetically silencing of KLF2

BackgroundHepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death worldwide, and the biology of this cancer remains poorly understood. Recent evidence indicates that long non-coding RNAs (lncRNAs) are found to be dysregulated in a variety of cancers, including HCC. Taurine Up-regulated Gene 1 (TUG1), a 7.1-kb lncRNA, recruiting and binding to polycomb repressive complex 2 (PRC2), is found to be disregulated in non-small cell lung carcinoma (NSCLC) and esophageal squamous cell carcinoma (ESCC). However, its clinical significance and potential role in HCC remain unclear.Methods and resultsIn this study, expression of TUG1 was analyzed in 77 HCC tissues and matched normal tissues by using quantitative polymerase chain reaction (qPCR). TUG1 expression was up-regulated in HCC tissues and the higher expression of TUG1 was significantly correlated with tumor size and Barcelona Clinic Liver Cancer (BCLC) stage. Moreover, silencing of TUG1 expression inhibited HCC cell proliferation, colony formation, tumorigenicity and induced apoptosis in HCC cell lines. We also found that TUG1 overexpression was induced by nuclear transcription factor SP1 and TUG1 could epigeneticly repress Kruppel-like factor 2 (KLF2) transcription in HCC cells by binding with PRC2 and recruiting it to KLF2 promoter region.ConclusionOur results suggest that lncRNA TUG1, as a growth regulator, may serve as a new diagnostic biomarker and therapy target for HCC.Electronic supplementary materialThe online version of this article (doi:10.1186/s12943-015-0431-0) contains supplementary material, which is available to authorized users.

The long noncoding RNA TUG1 regulates blood-tumor barrier permeability by targeting miR-144.

Blood-tumor barrier (BTB) limits the delivery of chemotherapeutic agent to brain tumor tissues. Long non-coding RNAs (lncRNAs) have been shown to play critical regulatory roles in various biologic processes of tumors. However, the role of lncRNAs in BTB permeability is unclear. LncRNA TUG1 (taurine upregulated gene 1) was highly expressed in glioma vascular endothelial cells from glioma tissues. It also upregulated in glioma co-cultured endothelial cells (GEC) from BTB model in vitro. Knockdown of TUG1 increased BTB permeability, and meanwhile down-regulated the expression of the tight junction proteins ZO-1, occludin, and claudin-5. Both bioinformatics and luciferase reporter assays demonstrated that TUG1 influenced BTB permeability via binding to miR-144. Furthermore, Knockdown of TUG1 also down-regulated Heat shock transcription factor 2 (HSF2), a transcription factor of the heat shock transcription factor family, which was defined as a direct and functional downstream target of miR-144. HSF2 up-regulated the promoter activities and interacted with the promoters of ZO-1, occludin, and claudin-5 in GECs. In conclusion, our results indicate that knockdown of TUG1 increased BTB permeability via binding to miR-144 and then reducing EC tight junction protein expression by targeting HSF2. Thus, TUG1 may represent a useful future therapeutic target for enhancing BTB permeability.