Long non-coding RNA TUG1 promotes colorectal cancer metastasis via EMT pathway

The Potential Dual Role of H2.0-like Homeobox in the Tumorgenesis and Development of Colorectal Cancer and Its Prognostic Value

Background

H2.0-like homeobox (HLX) is highly expressed in several hematopoietic malignancies. However, the role of HLX in the carcinogenesis and progression of colorectal cancer (CRC) patients has rarely been reported.

Methods

In this study, the data were collected from The Cancer Genome Atlas and Gene Expression Omnibus databases. The diagnostic value of HLX was analyzed by the R package "pROC." The overall survival was estimated using the "survival" and "survminer" packages. A nomogram was established to predict 1-, 3-, and 5-year overall survival of CRC patients. The CIBERSORT software was employed to calculate the relative proportions of 22 immune cells.

Results

HLX expression was downregulated in CRC patients. Remarkably, HLX expression was increased with stage (stage I-stage III) of CRC, and the CRC patients with high HLX expression exhibited a poor prognosis. The promoter methylation level of HLX was prominently increased in CRC samples compared to paracancerous samples. We also found that the six miRNAs target HLX genes, leading to its downregulation, and HLX expression had a negative correlation with its downstream target gene BRI3BP in both CRC and normal samples. Finally, we found that the 12 immune infiltrating cells were observably different between high and low HLX expression groups. The HLX had a significant positive correlation with 8 immune checkpoints (PD-1 (PDCD1), CTLA4, PDL-1 (CD274), PDL-2 (PDCD1LG2), CD80, CD86, LAG3, and TIGIT) expressions.

Conclusion

HLX probably played a carcinostasis role in the early stages of CRC but exhibited a cancer-promoting effect in the advanced stages. Meanwhile, HLX could serve as a reliable prognostic indicator for CRC.

Crosstalk between long non-coding RNAs and p53 signaling pathway in colorectal cancer: A review study

Colorectal cancer (CRC) is one of the most prevalent malignancies worldwide and the third leading cause of cancer-related fatalities. Long non-coding RNAs (lncRNAs) are key regulators of diverse physiological processes and are dysregulated in a wide range of pathophysiological circumstances such as CRC. Studies revealed that aberrant expressions of lncRNAs clearly modulate the expression level of p53 gene in CRC, thereby transactivating multiple downstream pathways. P53 is regarded as a crucial tumor suppressor gene which promotes cell-cycle arrest, DNA repair, senescence or apoptosis in response to cellular stresses. P53 is also mutated in CRC as well as various types of human malignancies. Therefore, lncRNAs interact with the p53 signaling pathway in numerus ways and significantly influence CRC-related processes. The current findings in the investigation of the crosstalk between lncRNAs and the P53 pathway in controlling CRC carcinogenesis, tumor progression, and therapeutic resistance are summarized in the this review. A deeper knowledge of CRC carcinogenesis may also have implications in CRC prevention and treatment through more research.

Comprehensive landscape and future perspectives of long noncoding RNAs (lncRNAs) in colorectal cancer (CRC): Based on a bibliometric analysis

This review aimed to use bibliometric analysis to sort out, analyze and summarize the knowledge foundation and hot topics in the field of long noncoding RNAs (lncRNAs) in colorectal cancer (CRC), and point out future trends to inspire related research and innovation. We used CiteSpace to analyze publication outputs, countries, institutions, authors, journals, references, and keywords. Knowledge foundations, hotspots, and future trends were then depicted. The overall research showed the trend of biomedical-oriented multidisciplinary. Much evidence indicates that lncRNA plays the role of oncogene or tumor suppressor in the occurrence and development of CRC. Besides, many lncRNAs have multiple mechanisms. lncRNAs and metastasis of CRC, lncRNAs and drug resistance of CRC, and the clinical application of lncRNAs in CRC are current research hotspots. Through insight into the development trend of lncRNAs in CRC, this study will help researchers extract hidden valuable information for further research.

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.

Insights on the potential oncogenic impact of long non-coding RNA nicotinamide nucleotide transhydrogenase antisense RNA 1 in different cancer types; integrating pathway(s) and clinical outcome(s) association

Long non-coding RNAs (lncRNAs) are becoming more prevalent in the cancer field arena, with functional roles in both oncogenic and onco-suppressive pathways. Despite their widespread aberrant expression in a range of human malignancies, the biological activities of the ncRNAs majority are unknown. All showed the involvement of the lncRNA nicotinamide nucleotide transhydrogenase antisense RNA 1 (NNT-AS1). Since NNT-AS1 influences cellular proliferation, invasion, migration, apoptosis, and metastasis, this lncRNA appears to be linked to deregulating the normal cellular processes driving malignancy. This was observed in breast cancer (BC), gastric cancer (GC), colorectal cancer (CRC), epithelial ovarian cancer (EOC), and hepatocellular carcinoma (HCC). The current narrative non-systematic review will discuss "the significance of lncRNAs in cancer", as well as "lncRNAs future potential application(s) as diagnostic or predictive biomarkers", therefore, comprising an opportunity as treatment target(s). The review will have a special emphasis on lncRNA NNT-AS1.

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.

LncRNA TUG1 promotes the migration and invasion in type I endometrial carcinoma cells by regulating E-N cadherin switch

OBJECTIVE

Accumulating evidence has demonstrated that lncRNA Taurine-upregulated gene 1 (TUG1) plays an important role in regulation of cell morphology, migration, proliferation and apoptosis. Our aim was to evaluate the oncogenic role of TUG1 in type I Endometrial Carcinoma (EC) and explore the precise mechanism of TUG1 involved in tumor progression.

MATERIALS AND METHODS

The GSE17025 data set was used to analyze the correlation of TUG1 expression with type I EC patients' prognosis. Furthermore, TUG1 expression profiles were measured by qRT-PCR from carcinoma tissues and adjacent nonneoplastic tissues (NNT) of 105 type I EC patients. The regulation of epithelial-mesenchymal transition (EMT) related molecules, p-AKT and AKT by TUG1 knockdown was investigated using Western blot analysis; meanwhile, the oncogenic roles of TUG1 were evaluated using cell viability and transwell migration/invasion assay in Hec-1-A and Ishikawa cell lines.

RESULTS

Firstly, we observed a significant association between higher TUG1 expression and lower survival rate in type I EC patients using the GSE17025 data set. A significant elevation of TUG1 levels was confirmed in type I EC tissues compared with NNT in the 105 type I EC patients, and high expression of TUG1 was associated with lymph vascular space invasion (LVSI) and lymph node metastasis (LNM). Subsequently, TUG1 knockdown could remarkably inhibit the Hec-1-A and Ishikawa cell invasion and migration in the functional experiment. Furthermore, our results showed that the protein levels of E-cadherin increased and N-cadherin decreased significantly, while β-catenin and Vimentin were not significantly altered upon TUG1 silencing in both Hec-1-A and Ishikawa cells. Finally, we found the p-AKT and AKT protein levels, and the rate of p-AKT/t-AKT has a tendency to be down-regulate in Hec-1-A cells, while the AKT pathway was not change significantly in Ishikawa cells after TUG1 knockdown.

CONCLUSION

Collectively, our data reveal that TUG1 might be regarded as an oncogenic molecule that promotes type I EC cells metastasis leading to tumor progression, at least partially, by regulating E-N cadherin switch and the AKT pathway.

The Role of SNHG15 in the Pathogenesis of Hepatocellular Carcinoma

Long non-coding RNAs (lncRNAs) are transcripts of more than 200 nucleotides which cannot be translated into proteins. Small nucleolar RNA host gene 15 (SNHG15) is a lncRNA whose dysregulation has been found to have an important impact on carcinogenesis and affect the prognosis of cancer patients in various cancer types. Hepatocellular carcinoma (HCC) is one of the most common cancers with a poor long-term prognosis, while the best prognostic factor of the disease is its early diagnosis and surgery. Consequently, the investigation of the mechanisms of hepatocarcinogenesis, as well as the discovery of efficient molecular markers and therapeutic targets are of great significance. An extensive literature search was performed in MEDLINE in order to identify clinical studies that tried to reveal the role of SNHG15 in HCC. We used keywords such as 'HCC', 'hepatocellular carcinoma', 'SNHG15' and 'clinical study'. Finally, we included four studies written in English, published during the period 2016-2021. It was revealed that SNHG15 is related to the appearance of HCC via different routes and its over-expression affects the overall survival of the patients. More assays are required in order to clarify the potential role of SNHG15 as a prognostic tool and therapeutic target in HCC.

SP1-mediated up-regulation of lncRNA TUG1 underlines an oncogenic property in colorectal cancer

The long non-coding RNA (lncRNA) taurine up-regulated gene 1 (TUG1) acts as tumor-promoting factor in colorectal cancer (CRC). We aimed to elucidate the mechanism by which the transcription factor specificity protein 1 (SP1) regulates TUG1 and microRNAs (miRs)/mRNAs in the context of CRC, which has not been fully studied before. Expression patterns of TUG1 and SP1 were determined in clinical CRC samples and cells, followed by identification of their interaction. Next, the functional significance of TUG1 in CRC was investigated. An in vivo CRC model was established to validate the effect of TUG1. The results demonstrated that TUG1 and SP1 were highly-expressed in CRC, wherein SP1 bound to the TUG1 promoter and consequently, positively regulated its expression. Silencing of TUG1 caused suppression of CRC cell growth and promotion of cell apoptosis. TUG1 could bind to miR-421 to increase KDM2A expression, a target gene of miR-421. TUG1 could activate the ERK pathway by impairing miR-421-targeted inhibition of KDM2A. Additionally, SP1 could facilitate the tumorigenesis of CRC cells in vivo by regulating the TUG1/miR-421/KDM2A/ERK axis. Altogether, the current study emphasizes the oncogenic role of TUG1 in CRC, and illustrates its interactions with the upstream transcription factor SP1 and the downstream modulatory axis miR-421/KDM2A/ERK, thus offering novel insights into the cancerogenic mechanism in CRC.

LncRNA TUG1 Promotes Apoptosis, Invasion, and Angiogenesis of Retinal Endothelial Cells in Retinopathy of Prematurity via MiR-145-5p

Purpose

Retinopathy of prematurity (ROP) is a common retinal vascular disease in premature neonates. In recent years, there is increasing evidence that the long non-coding RNA taurine upregulated gene 1 (TUG1) plays a regulatory role in vascular diseases, suggesting a potential role for TUG1 in vascular endothelial cells. We hypothesized that TUG1 may be associated with ROP. Our aim, therefore, was to explore the biological functions of TUG1 in aberrant retinal development.

Methods

We used the mouse oxygen-induced retinopathy (OIR) model to simulate the pathological changes of retinal in ROP. Quantitative real-time polymerase chain reaction was used to detect the expression of TUG1, miR-145-5p and cellular communication network factor 1 (CCN1). Human retinal endothelial cells (HRECs) were treated with CoCl₂ to mimic hypoxia conditions. Cellular functional changes were observed after transfection with RNA interference (RNAi)-TUG1 and miR-145-5p mimics. The apoptosis of HRECs was detected by flow cytometry, the migration ability was detected by wound healing and transwell migration assays, and the ability of angiogenesis was detected by tube formation assay. The potential binding sites between TUG1, miR-145-5p, and CCN1 were verified by dual-luciferase reporter assays. The degree of retinopathy was evaluated by staining retinal sections with hematoxylin and eosin, and the expression of CCN1, HIF-1α, VEGF, caspase-3, Bcl-2, IL-1β, and TNF-α protein was analyzed by Western blotting and immunohistochemistry.

Results

In the retina tissue of OIR mice, TUG1, miR-145-5p, and CCN1 were differentially expressed. Knocking down TUG1 attenuated apoptosis, migration, and angiogenesis induced by hypoxia on HRECs, as did miR-145-5p overexpression. Results from reporter assays indicate direct interactions between TUG1, miR-145-5p, and CCN1. Intravitreal injection of miR-145-5p mimics reduced the degree of retinopathy.

Conclusion

TUG1 acts as a molecular sponge of miR-145-5p to regulate CCN1 expression and thus regulate the development of retinal neovascularization. This regulatory mechanism may provide a new theoretical basis for the prevention and treatment of ROP.

The Emerging role of EMT-related lncRNAs in therapy resistance and their application as biomarkers

Cancer is the world's second largest cause of death. The most common cancer treatments are surgery, radiation therapy, and chemotherapy. Drug resistance, epithelial-to-mesenchymal transition (EMT), and metastasis are all pressing issues in cancer therapy today. Increasing evidence showed that drug-resistant and EMT are co-related with each other. Indeed, drug-resistant cancer cells possess enhanced EMT and invasive ability. Recent researches have demonstrated lncRNAs (long noncoding RNAs) are noncoding transcripts, which play an important role in the regulation of EMT, metastasis, and drug resistance in different cancers. However, the relationships among lncRNAs, EMT, and drug resistance are still unclear. These effects could be exerted via several signaling pathways such as TGF-β, PI3K-AKT, and Wnt/β-catenin. Identifying the crucial regulatory roles of lncRNAs in these pathways and processes leads to the development of novel targeted therapies. We review the key aspects of lncRNAs associated with EMT and therapy resistance. We focus on the crosstalk between lncRNAs and molecular signaling pathways affecting EMT and drug resistance. Moreover, each of the mentioned lncRNAs could be used as a potential diagnostic, prognostic, and therapeutic biomarker for cancer. Although, there are still many challenges to investigate lncRNAs for clinical applications.

Long Noncoding RNA Taurine-Upregulated Gene 1 Knockdown Protects Cardiomyocytes Against Hypoxia/Reoxygenation-induced Injury Through Regulating miR-532-5p/Sox8 Axis

BACKGROUND

Long noncoding RNA taurine-upregulated gene 1 (TUG1) has been reported to involve in the processing of cardiac ischemia/reperfusion injury after myocardial infarction. Thus, this study further investigates the underlying mechanisms of TUG1 in hypoxia/reoxygenation (H/R)-induced cardiomyocyte injury in vitro.

METHODS

Cell viability, apoptosis, and migration and invasion were detected using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, flow cytometry, and transwell assay, respectively. Western blot was used to examine the levels of matrix metallopeptidase 9, matrix metallopeptidase 2, and sex determining region Y-box transcription factor 8 (Sox8) protein. Levels of lactate dehydrogenase, malondialdehyde, superoxide dismutase, and glutathione peroxidase were detected using commercial kits. Levels of TUG1, microRNA-532-5p (miR-532-5p), and Sox8 were detected by quantitative real-time polymerase chain reaction. The interaction between miR-532-5p and Sox8 or TUG1 was confirmed by dual-luciferase reporter and RNA immunoprecipitation assay.

RESULTS

H/R induced rat cardiomyocyte H9c2 injury by inhibiting cell viability, migration and invasion, promoting cell apoptosis, and stimulating oxidative stress. H/R-induced H9c2 injury upregulated the level of TUG1, and TUG1 knockdown alleviated H/R-induced cardiomyocyte injury. TUG1 directly bound to miR-532-5p, and miR-532-5p inhibition reversed the action of TUG1 knockdown on H/R-induced cardiomyocyte injury. Sox8 was a target of miR-532-5p, and miR-532-5p blunted H/R-induced cardiomyocyte injury by targeting Sox8. In addition, TUG1 knockdown inhibited H/R-induced Sox8 elevation through miR-532-5p in H9c2 cells.

CONCLUSION

TUG1 silence ameliorated H/R-induced cardiomyocytes injury through regulating miR-532-5p/Sox8 axis, suggesting a potential therapeutic target for preventing myocardial ischemia/reperfusion injury.

Role of long noncoding RNA taurine-upregulated gene 1 in cancers

Long non-coding RNAs (lncRNAs) are a group of non-protein coding RNAs with a length of more than 200 bp. The lncRNA taurine up-regulated gene 1 (TUG1) is abnormally expressed in many human malignant cancers, where it acts as a competitive endogenous RNA (ceRNA), regulating gene expression by specifically sponging its corresponding microRNAs. In the present review, we summarised the current understanding of the role of lncRNA TUG1 in cancer cell proliferation, metastasis, angiogenesis, chemotherapeutic drug resistance, radiosensitivity, cell regulation, and cell glycolysis, as well as highlighting its potential application as a clinical biomarker or therapeutic target for malignant cancer. This review provides the basis for new research directions for lncRNA TUG1 in cancer prevention, diagnosis, and treatment.

Long noncoding RNAs: role and contribution in pancreatic cancer

Noncoding RNAs are proclaimed to be expressed in various cancer types and one such type is found to be pancreatic ductal adenocarcinoma (PDAC). The long noncoding RNAs (LncRNAs) affect the migration, invasion, and growth of tumor cells by playing important roles in the process of epigenesis, post-transcription, and transcriptional regulation along with the maintenance of apoptosis and cell cycle. It is quite subtle whether the alterations in lncRNAs would impact PDAC progression and development. This review throws a spotlight on the lncRNAs associated with tumor functions: MALAT-1, HOTAIR, HOXA13, H19, LINC01559, LINC00460, SNHG14, SNHG16, DLX6-AS1, MSC-AS1, ABHD11-AS1, DUXAP8, DANCR, XIST, DLEU2, etc. are upregulated lncRNAs whereas GAS5, HMlincRNA717, MIAT, LINC01111, lncRNA KCNK15-AS1, etc. are downregulated lncRNAs inhibiting the invasion and progression of PDAC. These data provided helps in the assessment of lncRNAs in the development, metastasis, and occurrence of PDAC and also play a vital role in the evolution of biomarkers and therapeutic agents for the treatment of PDAC.

DSCMF: prediction of LncRNA-disease associations based on dual sparse collaborative matrix factorization

BACKGROUND

In the development of science and technology, there are increasing evidences that there are some associations between lncRNAs and human diseases. Therefore, finding these associations between them will have a huge impact on our treatment and prevention of some diseases. However, the process of finding the associations between them is very difficult and requires a lot of time and effort. Therefore, it is particularly important to find some good methods for predicting lncRNA-disease associations (LDAs).

RESULTS

In this paper, we propose a method based on dual sparse collaborative matrix factorization (DSCMF) to predict LDAs. The DSCMF method is improved on the traditional collaborative matrix factorization method. To increase the sparsity, the L2,1-norm is added in our method. At the same time, Gaussian interaction profile kernel is added to our method, which increase the network similarity between lncRNA and disease. Finally, the AUC value obtained by the experiment is used to evaluate the quality of our method, and the AUC value is obtained by the ten-fold cross-validation method.

CONCLUSIONS

The AUC value obtained by the DSCMF method is 0.8523. At the end of the paper, simulation experiment is carried out, and the experimental results of prostate cancer, breast cancer, ovarian cancer and colorectal cancer are analyzed in detail. The DSCMF method is expected to bring some help to lncRNA-disease associations research. The code can access the https://github.com/Ming-0113/DSCMF website.

Down-Regulation of Long Non-Coding RNA TINCR Induces Cell Dedifferentiation and Predicts Progression in Oral Squamous Cell Carcinoma

Objectives

Recently long non-coding RNAs (lncRNAs) have emerged as novel gene regulators involved in tumorigenic processes, including oral squamous cell carcinoma (OSCC). Here, we identified a differentiation-related lncRNA, terminal differentiation-induced non-coding RNA (TINCR). However, its biological function and clinicopathological significance in OSCC still remain unclear.

Methods

The lncRNA expression profiles in OSCC tissues and paired adjacent non-tumor tissues (NATs) from 10 patients were detected by lncRNA microarrays. Weighted gene co-expression network analysis (WGCNA) and gene ontology (GO) enrichment were performed to identify the most significant module and module functional annotation, respectively. Potential differentiation-related lncRNAs were screened by differential expression analysis. TINCR was further confirmed in OSCC cell lines and tissues of another patient cohort by using qRT-PCR. The correlation between the TINCR expression level and clinicopathological characteristics was analyzed. The effects of TINCR on cell differentiation, migration and invasion were assessed by knockdown or knock-in in vitro and in vivo.

Results

WGCNA and GO enrichment analysis showed that one co-expression network was significantly enriched for epithelial cell differentiation, among which, TINCR was significantly downregulated. qRT-PCR analyses validated down-regulation of TINCR in tumor tissues compared with paired NATs, and its expression was closely correlated with pathological differentiation and lymph node metastasis in patients with OSCC. Patients with lower TINCR expression levels had worse survival. Cell function experiments showed that TINCR played a crucial role in epithelial differentiation. Both TINCR and epithelial differentiation-associated genes, including IVL and KRT4, were significantly upregulated during OSCC cell calcium-induced differentiation but were reduced when cell dedifferentiation occurred in tumor spheres. Overexpression of TINCR dramatically suppressed cell dedifferentiation, migration and invasion in vitro, while knockdown of TINCR had the opposite effects. Upregulation of TINCR significantly elevated the expression of terminal differentiation genes and repressed tumor growth in vivo. Moreover, TINCR significantly suppressed the activation of JAK2/STAT3 signaling in OSCC cells.

Conclusion

Our study suggests that TINCR functions as a tumor suppressor by inducing cell differentiation through modulating JAK2/STAT3 signaling in OSCC. TINCR may serve as a prognostic biomarker and therapeutic target for OSCC.

LncRNA TUG1 promotes esophageal cancer development through regulating PLK1 expression by sponging miR-1294

OBJECTIVES

Esophageal cancer is one of the malignant tumor with poor survival. The 5-year survival rate of esophageal cancer patients remains poor due to limited therapeutic options and the development of drug-resistance. Recent evidence suggests that long non-coding RNAs (lncRNAs) are involved in occurrence and development of tumor, however, the molecular mechanisms of lncRNA taurine-upregulated gene 1 (TUG1) in esophageal cancer remain unknown.

RESULTS

TUG1 was overexpressed in esophageal cancer tissues and cells. The knockdown of TUG1 repressed proliferation and invasion, while promoted apoptosis of esophageal cancer cells by negatively regulating miR-1294 expression. Furthermore, PLK1 was a target mRNA of miR-1294 in esophageal cancer cells. Therefore, the effects of PLK1 silencing on proliferation, apoptosis, and invasion of esophageal cancer cells could be overturned by silencing miR-1294. Additionally, TUG1 silencing inhibited growth of tumor cells in vivo.

CONCLUSIONS

TUG1 was found as oncogenic gene in esophageal cancer. Mechanically, TUG1 attributed to esophageal cancer process by regulating miR-1294/ PLK1 axis.

[Silencing long non-coding RNA HIF1A-AS2 inhibits proliferation, invasion and migration of cervical cancer cells in vitro]

OBJECTIVE

To explore the inhibitory effects of silencing long non-coding RNA (LncRNA) HIF1A-AS2 on epithelialmesenchymal transition (EMT) and tumor stem cell-like phenotype in cervical cancer cells.

METHODS

We designed 3 shRNA constructs for silencing HIF1A-AS2 in CaSki cells, and the shRNA with the strongest interference effect was selected for subsequent experiment. CaSki cells were transfected with shRNA-NC or Sh-HIF1A-AS2, and the changes in cell viability, invasion ability, EMT, expressions of EMT-related proteins, formation of cell spheres and expressions of stem cell markers were detected.

RESULTS

Transfection with shRNA-NC and Sh-HIF1A-AS2 did not significantly affected the viability of CaSki cells (P > 0.05). Compared with the cells transfected with shRNA-NC, the cells transfected with Sh- HIF1A-AS2 showed significantly reduced invasion ability, expressions of vimentin N-cadherin, and cell sphere formation ability. HIF1A-AS2 silencing obviously lowered the rate of ABCG2-positive cells, significantly reduced the mRNA and protein expressions of Nanog, OCT4, and SOX2, and strongly enhanced the expression of E-cadherin in CaSki cells (P < 0.05).

CONCLUSIONS

Silencing HIF1A-AS2 can inhibit proliferation, invasion and migration of cervical cancer cells in vitro.

Non coding RNAs as the critical factors in chemo resistance of bladder tumor cells

BACKGROUND

Bladder cancer (BCa) is the ninth frequent and 13th leading cause of cancer related deaths in the world which is mainly observed among men. There is a declining mortality rates in developed countries. Although, the majority of BCa patients present Non-Muscle-Invasive Bladder Cancer (NMIBC) tumors, only 30% of patients suffer from muscle invasion and distant metastases. Radical cystoprostatectomy, radiation, and chemotherapy have proven to be efficient in metastatic tumors. However, tumor relapse is observed in a noticeable ratio of patients following the chemotherapeutic treatment. Non-coding RNAs (ncRNAs) are important factors during tumor progression and chemo resistance which can be used as diagnostic and prognostic biomarkers of BCa.

MAIN BODY

In present review we summarized all of the lncRNAs and miRNAs associated with chemotherapeutic resistance in bladder tumor cells.

CONCLUSIONS

This review paves the way of introducing a prognostic panel of ncRNAs for the BCa patients which can be useful to select a proper drug based on the lncRNA profiles of patients to reduce the cytotoxic effects of chemotherapy in such patients.

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.

Biomarker Discovery for the Carcinogenic Heterogeneity Between Colon and Rectal Cancers Based on lncRNA-Associated ceRNA Network Analysis

Background

Colorectal cancer (CRC) is one of the leading causes of cancer death worldwide. Emerging evidence has revealed that risk factors and metastatic patterns differ greatly between colon and rectal cancers. However, the molecular mechanism underlying their pathogenic differences remains unclear. Therefore, we here aimed to identify non-coding RNA biomarkers based on lncRNA-associated ceRNA network (LceNET) to elucidate the carcinogenic heterogeneity between colon and rectal cancers.

Methods

A global LceNET in human was constructed by employing experimental evidence-based miRNA-mRNA and miRNA-lncRNA interactions. Then, four context-specific ceRNA networks related to cancer initiation and metastasis were extracted by mapping differentially expressed lncRNAs, miRNAs and mRNAs to the global LceNET. Notably, a novel network-based bioinformatics model was proposed and applied to identify lncRNA/miRNA biomarkers and critical ceRNA triplets for understanding the carcinogenic heterogeneity between colon and rectal cancers. Moreover, the identified biomarkers were further validated by their diagnostic/prognostic performance, expression pattern and correlation analysis.

Results

Based on network modeling, lncRNA KCNQ1OT1 (AUC>0.85) and SNHG1 (AUC>0.94) were unveiled as common diagnostic biomarkers for the initiation and metastasis of colon and rectal cancers. qRT-PCR analysis uncovered that these lncRNAs had significantly higher expression level in CRC cell lines with high metastatic potential. In particular, KCNQ1OT1 and SNHG1 function in colon and rectal cancers via different ceRNA mechanisms. For example, KCNQ1OT1/miR-484/ANKRD36 axis was involved in the initiation of colon cancer, while KCNQ1OT1/miR-181a-5p/PCGF2 axis was implicated in the metastasis of rectal cancer; the SNHG1/miR-484/ORC6 axis played a role in colon cancer, while SNHG1/miR-423-5p/EZH2 and SNHG1/let-7b-5p/ATP6V1F axes participated in the initiation and metastasis of rectal cancer, respectively. In these ceRNA triplets, miR-484, miR-181a-5p, miR-423-5p and let-7b-5p were identified as miRNA biomarkers with excellent distinguishing ability between normal and tumor tissues, and ANKRD36, PCGF2, EZH2 and ATP6V1F were closely related to the prognosis of corresponding cancer.

Conclusion

The landscape of lncRNA-associated ceRNA network not only facilitates the exploration of non-coding RNA biomarkers, but also provides deep insights into the oncogenetic heterogeneity between colon and rectal cancers, thereby contributing to the optimization of diagnostic and therapeutic strategies of CRC.

Network analysis of KLF5 targets showing the potential oncogenic role of SNHG12 in colorectal cancer

BACKGROUND

KLF5 is a member of the Kruppel-like factor, subfamily of zinc finger proteins that are involved in cancers. KLF5 functions as a transcription factor and regulates the diverse protein-coding genes (PCGs) in colorectal cancer (CRC). However, the long non-coding RNAs (lncRNAs) regulated by KLF5 in CRC are currently unknown.

METHODS

In this study, we first designed a computational pipeline to determine the PCG and lncRNA targets of KLF5 in CRC. Then we analyzed the motif pattern of the binding regions for the lncRNA targets. The regulatory co-factors of KLF5 were then searched for through bioinformatics analysis. We also constructed a regulatory network for KLF5 and annotated its functions. Finally, one of the KLF5 lncRNA targets, SNHG12, was selected to further explore its expression pattern and functions in CRC.

RESULTS

We were able to identify 19 lncRNA targets of KLF5 and found that the motifs of the lncRNA binding sites were GC-enriched. Next, we pinpointed the transcription factors AR and HSF1 as the regulatory co-factors of KLF5 through bioinformatics analysis. Then, through the analysis of the regulatory network, we found that KLF5 may be involved in DNA replication, DNA repair, and the cell cycle. Furthermore, in the cell cycle module, the SNHG12 up-regulating expression pattern was verified in the CRC cell lines and tissues, associating it to CRC invasion and distal metastasis. This indicates that SNHG12 may play a critical part in CRC tumorigenesis and progression. Additionally, expression of SNHG12 was found to be down-regulated in CRC cell lines when KLF5 expression was knocked-down by siRNA; and a strong correlation was observed between the expression levels of SNHG12 and KLF5, further alluding to their regulatory relationship.

CONCLUSIONS

In conclusion, the network analysis of KLF5 targets indicates that SNHG12 may be a significant lncRNA in CRC.

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.

The mechanisms of lncRNA Tug1 in islet dysfunction in a mouse model of intrauterine growth retardation

Taurine upregulated gene 1 (Tug1) is a novel lncRNA that participates in growth, and the abnormal expression of Tug1 related to mouse islet cell dysfunction. A recent study revealed that intrauterine growth retardation (IUGR) related to the pathogenesis of diabetes. Here, we aimed to explore the role and mechanism of Tug1 in IUGR-mediated islet dysfunction. We observed that newborn IUGR mice had lower body and pancreas weight and smaller islets than newborn control mice. After IUGR mice were given a normal diet, they showed catch-up growth and abnormal glucose tolerance; however, the pancreas/body weight ratio remained low. Blood glucose, serum insulin and related gene expression showed mild recovery after overexpression of Tug1 in IUGR mice. Furthermore, Tug1 was enriched in the nuclei of MIN6 cells. Using RIP and CHIP analyses we found that Tug1 could regulate Hes1 expression by binding to EZH2 to affect insulin synthesis in MIN6 cells. These findings indicate that lncRNA Tug1 could regulate the expression of Hes1 via EZH2-driven H3K27 methylation and affect insulin production. SIGNIFICANCE OF THE STUDY: This study suggests Tug1 as a novel biomarker, as it was shown to regulate β cell function and is worthy of further investigation due to its potential for diabetes treatment.

Long intergenic non-protein coding RNA 00475 silencing acts as a tumor suppressor in glioma under hypoxic condition by impairing microRNA-449b-5p-dependent AGAP2 up-regulation

Objective

Long non-coding RNAs have been demonstrated to be involved in the progression of a variety of cancers, including glioma. Through microarray analyses, long intergenic non-protein coding RNA 00475 (LINC00475) was identified in the glioma development. However, its potential role remains incompletely understood. This study aimed to elucidate the effect of LINC00475 on the development of glioma under hypoxic conditions.

Methods

Glioma cells underwent hypoxic treatment and were collected. The functional role of LINC00475 and AGAP2 in glioma was determined using ectopic expression, depletion, and reporter assay experiments. Then, the expression of LINC00475, microRNA (miR)-449b-5p, AGAP2, FAK, and HIF-1α was determined. In addition, cell migration and invasion were examined. Finally, a tumor xenograft was carried out in nude mice to explore the role of LINC00475 on oxidation in vivo.

Results

LINC00475 was identified to be overexpressed in hypoxic glioma samples, which was further observed to bind to and down-regulate miR-449b-5p, and negatively targeted AGAP2. Moreover, we also revealed a positive correlation between LINC00475 and AGAP2 expression in glioma. In addition, silencing of LINC00475 decreased the extent of FAK phosphorylation and reduced the expression of HIF-1α and AGAP2. It was also observed that LINC00475 silencing suppressed glioma cell proliferation, migration, and invasion, and promoted cell apoptosis. Moreover, oxidation of nude mice was promoted by LINC00475 silencing.

Conclusion

Taken together, LINC00475 silencing exerted an inhibitory effect on glioma under hypoxic conditions by down-regulating AGAP2 via up-regulation of miR-449b-5p.

Long non-coding RNA (lncRNA) and epithelial-mesenchymal transition (EMT) in colorectal cancer: a systematic review

BACKGROUND

Colorectal cancer (CRC) is a leading cause of cancer-related death. Epithelial-mesenchymal transition (EMT) is a major process in tumor metastasis development. This systematic review aims to describe the role of long non-coding RNA (lncRNA) in EMT in CRC.

METHODS

The electronic databases, PubMed, Cochrane, and EMBASE, were searched from January1990 to June 2019 to identify studies examining lncRNA and their role in mediating EMT in CRC. Studies examining clinical specimens and/or in vitro experiments were included.

RESULTS

In 61 identified studies, 54 lncRNAs were increased in CRC compared to normal colorectal epithelium. Increased lncRNA expression was frequently associated with worse survival. Many lncRNAs mediate their effect through competitive endogenous RNA or transcription factor regulation. The ZEB1, 2/E-cadherin, Wnt/β-catenin signaling, and chromatin remodeling pathways are discussed in particular.

CONCLUSIONS

lncRNAs are major regulators of EMT and predictor adverse outcome in CRC patients. Future research must focus on delineating lncRNA function prior to potential clinical use.

LINC00689 participates in proliferation, chemoresistance and metastasis via miR-31-5p/YAP/β-catenin axis in colorectal cancer

As a kind of high-incidence malignant tumors in the digestive tract, colorectal cancer (CRC) has extremely morbidity and mortality in the population. LncRNAs have been proved to regulate the proliferation, chemoresistance and metastasis of tumors including CRC. LINC00689 and miR-31-5p in CRC were found misregulated in CRC by TCGA analysis. However, the mechanism of LINC00689 and miR-31-5p in regulating CRC remains unknown. The expression levels of LINC00689, miR-31-5p and LATS2 in CRC tissues and cell lines were examined by qRT-PCR assay. Cell proliferation, metastasis (including invasion and migration) were quantified by MTT assay, colony formation and Transwell assay, respectively. Western blotting assay was then performed to verify the levels of YAP/β-catenin and metastasis-related proteins. Dual-luciferase reporter assay and RIP assay were performed to evaluate the interaction between LINC00689 (LATS2) and miR-31-5p. Moreover, the function of LINC00689 and miR-31-5p were confirmed by CRC xenograft in nude mice. LINC00689 was decreased while miR-31-5p was increased in CRC. The overexpression of LINC00689 or the knockdown of miR-31-5p inhibited cell proliferation, chemoresistance and metastasis of CRC cells. Meanwhile, the up-regulated LATS2 suppressed the activity of YAP/β-catenin pathway to repress CRC occurrence. Silencing LATS2 reversed the inhibition effects of overexpression of LINC00689 or knockdown of miR-31-5p on proliferation, chemoresistance and metastasis of CRC cells. LINC00689 indeed acted as a miR-31-5p sponge to inhibit CRC proliferation, chemoresistance and metastasis through up-regulating LATS2 and repressing YAP/β-catenin signaling pathway.

Inhibition of TUG1/miRNA-299-3p Axis Represses Pancreatic Cancer Malignant Progression via Suppression of the Notch1 Pathway

BACKGROUND AND AIMS

Taurine-upregulated gene 1 (TUG1) is reported to be upregulated and contributes to the progression of Pancreatic cancer (PC) by serving as an oncogene. Our aims were to explore the precise mechanism of TUG1 involved in PC pathogenesis.

METHODS

TUG1 and miR-299-3p expression profiles were measured by qRT-PCR. The direct interaction between TUG1 and miR-299-3p was explored by luciferase reporter assay. MTT assay, flow cytometry analysis, caspase-3 activity assay, Transwell invasion assay and wound healing assay were performed to evaluate cell proliferative ability, apoptosis, caspase-3 activity, invasion and migration, respectively. Western blot was conducted to examine the expressions of Ki67, Bax, Bcl-2, matrix metalloproteinase-2 (MMP-2), MMP-9, E-cadherin, N-cadherin, Snail, Notch1, Survivin, and CyclinD1. In addition, animal experiments were also implemented.

RESULTS

TUG1 was highly expressed, while miR-299-3p was underexpressed in PC tissues and PC cells. Furthermore, the significant increase of TUG1 in PC tissues of advanced patients (stage 3/4) was observed compared to patients (stage 1/2). TUG1 was negatively correlated with miR-299-3p expression in PC tissues. Moreover, TUG1 functioned as a molecular sponge of miR-299-3p to repress its expression. TUG1 knockdown suppressed cell proliferation, invasion, migration, and epithelial-mesenchymal transition (EMT), and induced apoptosis in PC cells, and repressed tumor growth and EMT in PC xenograft models, which were reversed following reintroduction with anti-miR-299-3p. Furthermore, we found that TUG1 silencing inactivated the Notch1 pathway in PC by upregulating miR-299-3p.

CONCLUSIONS

The results reported that inhibition of TUG1/miR-299-3p axis suppressed PC malignant progression via suppression of the Notch1 pathway.

RETRACTED: Long non-coding RNA LINC00160 functions as a decoy of microRNA-132 to mediate autophagy and drug resistance in hepatocellular carcinoma via inhibition of PIK3R3

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the authors. Following the publication of the above article, the authors found that “LINC00160 did not affect Atg5 and P65 protein expression in HCC cells, which was inconsistent with the result of this paper. Furthermore, we apologize to the readership of the Journal for any inconvenience caused.” Additionally, after publication, the journal was made aware of comments in relation to this article (https://pubpeer.com/publications/333AE65483683ADF50A723BE34AD62). The authors have not responded to our request to respond to these comments.

The long noncoding RNA TUG1 is required for TGF-β/TWIST1/EMT-mediated metastasis in colorectal cancer cells

Colorectal cancer (CRC) is one of the leading causes of cancer death worldwide, and metastasis is the major cause of CRC-related mortality. Transforming growth factor-beta (TGF-β) has a central role not only in the regulation of the normal colon but also in the development and metastasis of CRC. However, TGF-β is not considered an ideal therapeutic target because it shows both pro-tumorigenic and anti-tumorigenic activity, depending on the tumor stage. Therefore, it is important to find a downstream signaling component of TGF-β that can be targeted to impair CRC metastasis. Here, we show that TGF-β promotes CRC migration and upregulates the expression of long-noncoding RNA Taurine Upregulated Gene 1 (TUG1). TUG1 knockdown inhibited migration, invasion, and epithelial-mesenchymal transition (EMT) of CRC cells in vitro, and reduced CRC lung metastasis in vivo. TGF-β induced metastasis, and TUG1 knockdown inhibited these effects. In addition, TGF-β could not reverse the anti-metastasis effects of TUG1 knockdown. These data demonstrate that TUG1 is a downstream molecular of TGF-β. Moreover, TWIST1 expression was increased with TGF-β treatment, and TUG1 knockdown decreased TWIST1 expression in CRC cells. TWIST1 knockdown inhibited invasion and EMT in CRC cells; these effects were not changed by simultaneous TUG1 knockdown, indicating that TWIST1 is a downstream mediator of TUG1. Moreover, TUG1 was significantly overexpressed in CRC patients. In conclusion, TGF-β promotes metastasis of CRC via a TUG1/TWIST1/EMT signaling pathway. TUG1 may be a promising drug target to inhibit TGF-β pathway activation in the treatment of CRC.

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 RNA TUG1-mediated down-regulation of KLF4 contributes to metastasis and the epithelial-to-mesenchymal transition of colorectal cancer by miR-153-1

Introduction

Taurine up-regulated 1 (TUG1) was reported to be over-expressed and involved in various human malignancies. However, its expression status and mechanistic importance in colorectal cancer (CRC) were yet to be defined.

Methods

Relative expressions of TUG1, miR-153-1 and Kruppel-like factor 4 (KLF4) were analyzed by real-time PCR. The potential influences of TUG1-proficiency and miR-153-1-deficiency on cell proliferation, migration and viability were determined by colony formation, wound healing and CCK-8 assays, respectively. Cell invasion was evaluated by transwell chamber assay. The regulatory effect of KLF4 on miR-153-1 was interrogated by luciferase reporter assay. Direct association between KLF4 and miR-153-1 promoter was measured by chromatin immunoprecipitation (ChIP) assay. Subcellular localization of TUG1 was determined by fractionization PCR. Enrichment of EZH2 on KLF4 promoter was analyzed by ChIP-PCR. The pro-tumoral activity of TUG1 was determined using xenograft tumor model.

Results

We demonstrated the over-expression of TUG1 and down-regulation of miR-153-1 in CRC. Knockdown of TUG1 or ectopic over-expression of miR-153-1 in SW480 significantly suppressed cell proliferation, migration and viability. TUG1 negatively modulated miR-153-1 expression, and simultaneous expression of TUG1 completely abolished the anti-tumor effect of miR-153-1. We further identified KLF4 as a transcription factor of miR-153-1, which was negatively regulated by TUG1 along with EZH2.

Conclusion

Our study unravels the critical involvement of TUG1/KLF4/miR-153-1 axis in CRC.

Diagnostic and prognostic potential of tissue and circulating long non-coding RNAs in colorectal tumors

Long non-coding RNAs (lncRNAs) are members of the non-protein coding RNA family longer than 200 nucleotides. They participate in the regulation of gene and protein expression influencing apoptosis, cell proliferation and immune responses, thereby playing a critical role in the development and progression of various cancers, including colorectal cancer (CRC). As CRC is one of the most frequently diagnosed malignancies worldwide with high mortality, its screening and early detection are crucial, so the identification of disease-specific biomarkers is necessary. LncRNAs are promising candidates as they are involved in carcinogenesis, and certain lncRNAs (e.g., CCAT1, CRNDE, CRCAL1-4) show altered expression in adenomas, making them potential early diagnostic markers. In addition to being useful as tissue-specific markers, analysis of circulating lncRNAs (e.g., CCAT1, CCAT2, BLACAT1, CRNDE, NEAT1, UCA1) in peripheral blood offers the possibility to establish minimally invasive, liquid biopsy-based diagnostic tests. This review article aims to describe the origin, structure, and functions of lncRNAs and to discuss their contribution to CRC development. Moreover, our purpose is to summarise lncRNAs showing altered expression levels during tumor formation in both colon tissue and plasma/serum samples and to demonstrate their clinical implications as diagnostic or prognostic biomarkers for CRC.

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.

LncRNA TUG1 promotes the development of osteosarcoma through RUNX2

The lncRNA taurine-upregulated gene 1 (TUG1) is known to serve a role as an oncogene in the development of a number of human malignancies. However, the functionality of TUG1 in osteosarcoma remains poorly characterized. Therefore, the aim of the present study was to explore the role of TUG1 in osteosarcoma. TUG1 expression in tumor tissues, adjacent healthy tissues and plasma from 40 osteosarcoma patients and 40 healthy controls was detected using reverse transcription-quantitative PCR. Receiver operating characteristic curves were used to analyze the diagnostic value of TUG1 for osteosarcoma while the prognostic value of TUG1 for osteosarcoma was analyzed using the Kaplan-Meier method. TUG1 expression vectors and siRNAs were transfected into MG-63 and U2OS osteosarcoma cell lines, and the effects on osteosarcoma cell viability, migration and invasion were tested using Cell Counting kit-8 and Transwell assays. The effects of TUG1 overexpression on runt-related transcription factor 2 (RUNX2) expression were also detected using western blotting. TUG1 expression was found to be significantly higher in osteosarcoma tissues compared with adjacent healthy tissues, and in the plasma of osteosarcoma patients compared with healthy controls. TUG1 expression also exhibited significant diagnostic and prognostic value for osteosarcoma. TUG1 overexpression and knockdown respectively increased and reducedosteosarcoma cell viability, migration and invasion. In addition, TUG1 overexpression upregulated RUNX2 expression. These results suggest that lncRNA TUG1 may promote the development of osteosarcoma by modulating RUNX2 and TUG1 expression, which can serve as prognostic and diagnostic markers for this malignancy.

LINC00472 Acts as a Tumor Suppressor in NSCLC through KLLN-Mediated p53-Signaling Pathway via MicroRNA-149-3p and MicroRNA-4270

Long non-coding RNAs and microRNAs (miRNAs) have been reported to participate in the progression of non-small-cell lung cancer (NSCLC). Long intergenic non-protein-coding RNA 472 (LINC00472), miR-149-3p, and miR-4270 were found to be involved in tumor activities, suggesting potential roles in NSCLC. Thus, this study aimed to examine the ability of LINC00472 to influence the progression of NSCLC with the involvement of miR-149-3p and miR-4270. Initially, differentially expressed long non-coding RNAs (lncRNAs), downstream regulatory miRNAs, and genes related to NSCLC were identified. Next, the interaction among LINC00472, miR-149-3p and miR-4270, and KLLN and the p53-signaling pathway was determined. The effect of LINC00472 on the expression of E-cadherin, N-cadherin, and Vimentin was examined through gain-of-function and loss-of-function experiments. Lastly, the effects of LINC00472 on NSCLC tumor growth were assessed in vivo. LINC00472 and KLLN were found to exhibit low levels, while miR-149-3p and miR-4270 were highly expressed in NSCLC. In addition, the overexpression of LINC00472 was observed to upregulate KLLN and activate the p53-signaling pathway, which ultimately inhibited the invasion, migration, and EMT of NSCLC cells via miR-149-3p and miR-4270, corresponding to decreased N-cadherin and Vimentin and increased E-cadherin. The overexpression of LINC00472 exerted an inhibitory effect on tumor growth in vivo. Taken together, the key evidence suggests that the overexpression of LINC00472 can downregulate miR-149-3p and miR-4270 to upregulate KLLN and activate the p53-signaling pathway, thus inhibiting the development of NSCLC. This study highlights the potential of LINC00472 as a promising therapeutic target for NSCLC treatment.

Nr5a2 promotes tumor growth and metastasis of gastric cancer AGS cells by Wnt/beta-catenin signaling

Purpose: Nr5a2 (nuclear receptor subfamily 5 group A member 2, also known as LRH-1), which belongs to the NR5A (Ftz-F1) subfamily of nuclear receptors, is a key regulator in stem cell pluripotency and the development of several types of cancer. However, the data are controversial. Since Nr5a2 plays different roles in multiple types of cancer and the function of Nr5a2 in gastric cancer (GC) has not been revealed, we studied the role and molecular mechanism of Nr5a2 in GC. Methods: In this study, we have investigated the effect of Nr5a2 on tumor growth and metastasis by in vivo and in vitro models. Results: The results showed that knockdown of Nr5a2 could inhibit cell proliferation via arresting the cell cycle in the G2/M phase and suppress cell mobility through preventing the epithelial-mesenchymal transition (EMT) process in AGS cells. In addition, knockdown of Nr5a2 could suppress tumorigenesis and metastasis of AGS cells in vivo. We also demonstrated that knockdown of Nr5a2 inhibited cellular proliferation and mobility by suppressing the Wnt/beta-catenin signaling pathway. Conclusion: Nr5a2 may act as an oncogene in GC development. The EMT process and the Wnt/beta-catenin signaling pathway play an important role in the Nr5a2 induced GC development.

The long noncoding RNA TPTE2P1 promotes the viability of colorectal cancer cells

Long noncoding RNAs (lncRNAs) have important functions in tumor development and progression, including colorectal cancer (CRC), but their roles are not completely understood. In this study, the roles of the lncRNA transmembrane phosphoinositide 3-phosphatase and tensin homolog 2 pseudogene 1 (TPTE2P1), previously implicated in gallbladder cancer cell migration and invasion, were evaluated in CRC. In particular, quantitative polymerase chain reaction was used to quantify TPTE2P1 levels in tumor tissues and cell lines. The association between TPTE2P1 and survival was analyzed using the online tool OncoLnc. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, colony formation assays, and flow cytometry were used to evaluate the effects of TPTE2P1 on viability, cell cycle progression, and apoptosis. Signaling pathway proteins were quantitated by Western blot analysis. Finally, the role of TPTE2P1 was analyzed in vivo using mouse models. TPTE2P1 levels were significantly higher in CRC tissues than in adjacent normal tissues. Higher expression was associated with a poor survival rate. The silencing of TPTE2P1 led to cell cycle arrest at the S phase and thereby inhibited cell viability. TPTE2P1 knockdown also caused cancer cell apoptosis via the activation of the apoptosis regulator (BCL2)/caspase 3 signaling cascade. In addition, the inhibition of TPTE2P1 had suppressive effects on tumors in vivo. TPTE2P1 is upregulated in CRC and plays essential roles in the regulation of cell viability in vitro and tumor formation in vivo.

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.

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.

Identification of cancer-related potential biomarkers based on lncRNA-pseudogene-mRNA competitive networks

Accumulating evidence indicates that mRNAs and noncoding RNAs act as competitive endogenous RNAs (ceRNAs) and play a key role in tumorigenesis. However, the complex competitive relationship among genes remains unknown. In the present study, the long noncoding RNAs (lncRNAs), pseudogenes and mRNAs that compete with common microRNAs are defined as lncRNA-pseudogene-mRNA competitive triples. We find that some candidate ceRNAs, modules and triples are associated with cancers and can significantly divide patients into high-risk and low-risk groups; thus, they may serve as potential cancer biomarkers. In sum, the present study systematically analyzes the association between competitive triples and cancer, which provides a reference for a deeper understanding of cancer progression.

Long non-coding RNA RUNX1-IT1 plays a tumour-suppressive role in colorectal cancer by inhibiting cell proliferation and migration

Long non-coding RNAs (lncRNAs) have been demonstrated to be involved in the progression of various cancers. In this study, we aim to investigate the role of lncRNA RUNX1-IT1 in the development of colorectal cancer (CRC). The expression levels of lncRNA RUNX1-IT1 were measured using quantitative real-time Polymerase Chain Reaction(qRT-PCR). CCK8 proliferation assay, transwell assay, and flow cytometry were performed to evaluate the effect of lncRNA RUNX1-IT1 on CRC cell proliferation, migration, and apoptosis. The proliferation markers (PCNA, Ki67), apoptosis markers (cleaved-PARP, cleaved-caspase3), and MMP9 are detected by western blotting. Significant down regulation of lncRNA RUNX1-IT1 was measured in CRC tissues and three CRC cell lines (HCT116, HT29, and RKO) compared with paired nontumorous adjacent tissues (P < 0.01) or the normal colonic epithelial cell line FHC (P < 0.05), respectively. Moreover, the proliferative and migration potential of CRC cells were inhibited by overexpressing lncRNA RUNX1-IT1, which could be obviously improved by knocking down lncRNA RUNX1-IT1. The protein levels of PCNA, Ki67, and MMP9 were upregulated by overexpressing lncRNA RUNX1-IT1 and down regulated in si-RUNX1-IT1 cells. Besides, lncRNA RUNX1-IT1 could also promote the apoptosis of CRC cells. In conclusion, lncRNA RUNX1-IT1 is downregulated in CRC and plays a tumour-suppressive role due to the regulatory of cell proliferation, migration, and apoptosis. SIGNIFICANCE OF THE STUDY: We demonstrated that lncRNA RUNX1-IT1 was down regulated both in CRC tissues and cell lines. Besides, lncRNA RUNX1-IT1 could serve as a potential diagnostic biomarker and play a tumour-suppressive role owing to its good diagnostic efficacy and inhibition of CRC cell proliferation and migration.

Long Noncoding RNA TUG1/miR-29c Axis Affects Cell Proliferation, Invasion, and Migration in Human Pancreatic Cancer

Given the low resection rate and chemoresistance of patients with pancreatic cancer (PC), their survival rates are typically poor. Long noncoding RNAs (lncRNAs) have recently been shown to play an important role in tumourigenesis and human cancer progression, including in PC. In this study, we aimed to investigate the role of taurine-upregulated gene 1 (TUG1) in PC. A quantitative polymerase chain reaction was used to analyse TUG1 expression in PC tissues and peritumoural normal tissues. TUG1 was overexpressed in PC tissues compared with that in peritumoural normal tissues, and the high expression of TUG1 was associated with the poor prognosis of patients with PC. Furthermore, TUG1 knockdown significantly inhibited the proliferation and invasion of PC cells both in vitro and in vivo, while overexpression TUG1 promoted tumour cell proliferation, migration, and invasion. TUG1 directly targeted miR-29c, a tumour suppressor in several cancers. TUG1 knockdown significantly increased the expression of miR-29c and subsequently induced the downregulation of integrin subunit beta 1 (ITGB1), matrix metalloproteinase-2 (MMP2), and matrix metalloproteinase-9 (MMP9). The downregulation of miR-29c abolished the TUG1 knockdown-mediated inhibition of tumour growth in vitro and in vivo, whereas the upregulation of miR-29c enhanced the effects of TUG1 knockdown on PC cells. In conclusion, we demonstrate for the first time the oncogenic role of TUG1 in PC. The downregulation of TUG1 significantly inhibited the growth and migratory ability of PC cells in vitro and in vivo by targeting miR-29c. Our study provides a novel potential diagnostic biomarker and therapeutic target for PC.

Dysregulation of KCNQ1OT1 promotes cholangiocarcinoma progression via miR-140-5p/SOX4 axis

It is commonly recognized that aberrant expression of long non-coding RNAs (lncRNAs) is an important cause of cancer progression. The oncogenic property of KCNQ1OT1 has been identified in several malignant tumors. Here, we decided to explore the biological function and molecular mechanism of KCNQ1OT1 in cholangiocarcinoma (CCA). The expression conditions of KCNQ1OT1 in different tissues and cell lines were examined with qRT-PCR analysis. As expected, KCNQ1OT1 was highly expressed in CCA tissues and cell lines. Results of functional assays revealed the oncogenic function of KCNQ1OT in cholangiocarcinoma progression. The positive effect of KCNQ1OT1 on cell proliferation, invasion and epithelial-mesenchymal transition was identified by performing MTT assay, colony formation assay, transwell invasion assay and western blotting. Whereas, the negative effect of KCNQ1OT1 on the cell apoptosis was tested with flow cytometry analysis. Mechanism investigation revealed that KCNQ1OT1 can act as a ceRNA to improve CCA progression by regulating miR-140-5p/SOX4 axis. Recue assays were conducted to demonstrate the actual effects of KCNQ1OT1-miR-140-5p-SOX4 pathway on CCA progression.

lncRNAs in Non-Malignant Tissue Have Prognostic Value in Colorectal Cancer

Although colorectal cancer (CRC) is the third most frequent cause of cancer related death in Europe, clinically relevant biomarkers for therapy guidance and prognosis are insufficiently reliable. Long non-coding RNAs (lncRNAs) are RNAs over 200 nucleotides long that are not translated into proteins but can influence biological processes. There is emerging evidence for their involvement in solid cancer as oncogenes, tumour suppressors or regulators of cell proliferation and metastasis development. The goal of this study was to evaluate the prognostic effect of selected lncRNAs in a retrospective study on CRC patients from the Czech Republic. We used a quantitative PCR approach to measure the expression in paired non-malignant and tumour tissue samples of CRC patients of nine lncRNAs previously shown to be involved in cancer progression—ANRIL, CCAT1, GAS5, linc-ROR, MALAT1, MIR155HG, PCAT1, SPRY4-IT1 and TUG1. Associations between expression and expression ratios and clinical characteristics and survival were assessed by using univariable Cox proportional hazards models, Kaplan-Meier estimations with the Gehan-Wilcoxon test, the Mann-Whitney U test, the Kruskal-Wallis test and Spearman’s correlations. A comparison of expression in tumour tissue (TT) and non-malignant mucosa tissue (MT) showed significant upregulation of CCAT1 and linc-ROR in TT (p < 0.001 and p = 0.001, respectively) and downregulation of ANRIL, MIR155HG and MALAT1 (p = 0.001, p = 0.010, p = 0.001, respectively). Linc-ROR was significantly associated with the presence of synchronous metastases (p = 0.033). For individual tissue types, lower MIR155HG expression in TT was correlated with both shorter overall survival (p = 0.008) and shorter disease-free survival (p = 0.040). In MT, expression ratios of CCAT1/ANRIL and CCAT1/MIR155HG were associated with overall survival (p = 0.005 and p = 0.006, respectively). Our results revealed that changes in expression of lncRNAs between MT and TT hold potential to be used as prognostic biomarkers in CRC patients. Moreover, the ratios of CCAT1 to ANRIL and MIR155HG in MT also exhibit potential for prognosis assessment without tumour sampling. Our results also indicate that cancer progression is associated with detrimental system-wide changes in patient tissue, which might govern patient survival even after successful elimination of tumour or cancerous cells.

Screening key long non-coding RNAs in early-stage colon adenocarcinoma by RNA-sequencing

AIM

We aim to identify the key long noncoding RNAs (lncRNAs) in early-stage colon adenocarcinoma (COAD).

PATIENTS & METHODS

Compared with colonic intraepithelial neoplasia, differentially expressed lncRNAs (DElncRNAs) in early-stage COAD were obtained by RNA-sequencing. Our previous work has obtained the differentially expressed mRNAs and miRNAs (DEmRNAs and DEmiRNAs) in early-stage COAD. DEmiRNA-DElncRNA-DEmRNA interaction analysis and functional annotation were performed. Validation of expression and receiver-operating characteristic analyses were performed based on The Cancer Genome Atlas.

RESULTS

Seventy-nine significantly DElncRNAs in early-stage COAD were obtained. MiR-153-3p-TUG1-DAPK1/ARNT2/KLK3/PLD1/SMAD2 and miR-153-3p-SNHG17-COL11A1/IGFBP3/KLF6 interactions were associated with early-stage COAD. Five DElncRNAs (ELFN1-AS1, LINC01234, SNHG17, UCA1 and LOC101929549) involved in early-stage COAD with potential diagnostic value.

CONCLUSION

LncRNAs involve in early-stage COAD by interaction with COAD-regulated genes and miRNAs.

Long noncoding RNA expression in the cervix mid-pregnancy is associated with the length of gestation at delivery

Infants born preterm are at increased risk of multiple morbidities and mortality. Why some women deliver preterm remains poorly understood. Prior studies have shown that cervical microRNA expression and DNA methylation are associated with the length of gestation. However, no study has examined the role of long noncoding RNAs (lncRNAs) in the cervix during pregnancy. To determine whether expression of lncRNAs is associated with length of gestation at delivery, we analyzed RNA from cervical swabs obtained from 78 women during pregnancy (mean 15.5, SD 5.0, weeks of gestation) who were participating in the Spontaneous Prematurity and Epigenetics of the Cervix (SPEC) Study in Boston, MA, USA. We used a PCR-based platform and found that 9 lncRNAs were expressed in at least 50% of the participants. Of these, a doubling of the expression of TUG1, TINCR, and FALEC was associated with shorter lengths of gestation at delivery [2.8 (95% CI: 0.31, 5.2); 3.3 (0.22, 6.3); and 4.5 (7.3, 1.6) days shorter respectively]. Of the lncRNAs analyzed, none was statistically associated with preterm birth, but expression of FALEC was 2.6-fold higher in women who delivered preterm vs. term (P = 0.051). These findings demonstrate that lncRNAs can be measured in cervical samples obtained during pregnancy and are associated with subsequent length of gestation at delivery. Further, this study supports future work to replicate these findings in other cohorts and perform mechanistic studies to determine the role of lncRNAs in the cervix during pregnancy.

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.

MicroRNAs, long noncoding RNAs, and circular RNAs: potential tumor biomarkers and targets for colorectal cancer

Noncoding RNAs (ncRNAs) can be divided into microRNAs (miRNAs), long noncoding RNAs (lncRNAs), circular RNAs (circRNAs), pRNAs, and tRNAs. Traditionally, miRNAs exert their biological function mainly through the inhibition of translation via the induction of target RNA transcript degradation. lncRNAs and circRNAs were once considered to have no potential to code proteins. Here, we will review the current knowledge on ncRNAs in relation to their origins, characteristics, and functions. We will also review how ncRNAs work as competitive endogenous RNA, gene transcription and expression regulators, and RNA-binding protein sponges in colorectal cancer (CRC). Notably, except for the abovementioned mechanisms, recent advances revealed that lncRNAs can also act as the precursor of miRNAs, and a small portion of lncRNAs and circRNAs was verified to have the potential to code proteins, providing new evidence for the significance of ncRNAs in CRC tumorigenesis and development.