Upregulation of long noncoding RNA ZEB1-AS1 promotes tumor metastasis and predicts poor prognosis in hepatocellular carcinoma

lncRNAs as prognostic molecular biomarkers in hepatocellular carcinoma: a systematic review and meta-analysis

The latest studies have shown that long non-coding RNAs (lncRNAs) may be considered markers as their expression levels were abnormal in cancer and can be used as a molecular biomarker for the potential assessment of cancer prognosis. In this study, we aimed to assess the prognostic value of lncRNA as marker of patients with hepatocellular carcinoma. We performed a detailed search of the PubMed and Embase databases for articles on the prognostic value of various lncRNAs in HCC. We then carefully extracted the relevant data from the articles, and we used the meta-analysis method to analyze these results; heterogeneity and publication bias were also evaluated. With 40 associative studies included, we found that high expression of 27 types of lncRNA was associated with a poor prognosis in HCC patients, and low expression of 18 types of lncRNAs was associated with a worse prognosis. Patients with higher lncRNA expression had significantly poor overall survival (OS; pooled HR, 1.25; 95% confidence interval [CI], 1.03–1.52) as well as significantly poor recurrence-free survival (RFS; pooled HR, 1.66; 95% CI, 1.26–2.17). Overexpression of lncRNAs may not meaningfully predict disease-free survival (DFS; pooled HR, 1.04; 95% CI, 0.52–2.07; p = 0.91). Our meta-analysis demonstrated that lncRNAs may serve as predictive biomarkers for cancer prognosis.

The short and the long: non-coding RNAs and growth factors in cancer progression

A relatively well-understood multistep process enables mutation-bearing cells to form primary tumours, which later use the circulation system to colonize new locations and form metastases. However, in which way the emerging abundance of different non-coding RNAs supports tumour progression is poorly understood. Here, we review new lines of evidence linking long and short types of non-coding RNAs to signalling pathways activated in the course of cancer progression by growth factors and by the tumour micro-environment. Resolving the new dimension of non-coding RNAs in oncogenesis will probably translate to earlier detection of cancer and improved therapeutic strategies.

Long noncoding RNA expression profiles in sub-lethal heat-treated hepatoma carcinoma cells

Background

Sub-lethal heat treatment characterizes a transition zone of radiofrequency ablation (RFA) which explains hepatocellular carcinoma (HCC) residual cancer occurrence in this area after RFA treatment. The biochemistry of residual cancer cell recurrence is poorly understood, but long noncoding RNAs (lncRNAs) may have aberrant expression that is associated with diverse cancers. Thus, we measured lncRNA gene expression in sub-lethally heat-treated HCC cells using microarray.

Method

Differentially expressed lncRNA and mRNA were measured with an Agilent Human lncRNA + mRNA Array V4.0 (4 × 180 K format) containing 41,000 lncRNAs and 34,000 mRNAs. Bioinformatics analysis was used to assess differentially expressed lncRNA and mRNA. Seven lncRNA and seven mRNA were validated by qRT-PCR analysis in HCC cells.

Results

Genome-wide lncRNA and mRNA expression data in sub-lethal heat-treated SMMC-7721 HCC cells 558 lncRNA and 250 mRNA were significantly up-regulated and 224 lncRNA and 1031 mRNA down-regulated compared to normal cultured SMMC-7721 cells. We demonstrated for the first time that ENST00000570843.1, ENST00000567668.1, ENST00000582249.1, ENST00000450304.1, TCONS_00015544, ENST00000602478.1, TCONS_00001266 and ARC, IL12RB1, HSPA6 were upregulated, whereas STAT3, PRPSAP1, MCU, URB2 were down-regulated in sub-lethally heat-treated HCC cells.

Conclusions

lncRNA expression data in sub-lethally heat-treated HCC cells will provide important insights about lncRNAs’ contribution to HCC recurrence after RFA treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s12957-017-1194-4) contains supplementary material, which is available to authorized users.

High expression of long non-coding RNA ZEB1-AS1 promotes colorectal cancer cell proliferation partially by suppressing p15 expression

This study aims to investigate the function of long non-coding RNA ZEB1-AS1, reveal its molecular mechanism in colorectal cancer cell growth, and evaluate its clinical significance in colorectal cancer patients. ZEB1-AS1 has reported in the development of several cancers, but the biological role of it in colorectal cancer has not been discussed. In this report, ZEB1-AS1 expression level was measured with quantitative real-time polymerase chain reaction in 63 pairs of colorectal cancer tissues and paired adjacent non-tumor colorectal tissues. The relationship between ZEB1-AS1 expression and overall survival was analyzed by virtue of Kaplan-Meier analysis. Subsequently, small interfering RNA or lentivirus vector-mediated lncRNA ZEB1-AS1 was transfected into colorectal cancer cell lines. Cell viability and apoptosis were examined. Later, nude mouse transplantation experiment was conducted to evaluate the effect of ZEB1-AS1 on colorectal cancer development in vivo. It turns out that ZEB1-AS1 is upregulated in colorectal cancer tissues and its expression is significantly associated with overall survival rate and recurrence-free survival. Upregulation of ZEB1-AS1 colorectal cancer promotes cell proliferation and inhibits cell apoptosis. In addition, cell cycle inhibitory protein p15 participates in the oncogenic function of ZEB1-AS1. Collectively, ZEB1-AS1 has asignificant effect on colorectal cancer pathological process and serves as a valuable prognostic biomarker for colorectal cancer.

Identification of four prognostic LncRNAs for survival prediction of patients with hepatocellular carcinoma

Background

As the fifth most common cancer worldwide, Hepatocellular carcinoma (HCC) is also the third most common cause of cancer-related death in China. Several lncRNAs have been demonstrated to be associated with occurrence and prognosis of HCC. However, identification of prognostic lncRNA signature for HCC with expression profiling data has not been conducted yet.

Methods

With the reuse of public available TCGA data, expression profiles of lncRNA for 371 patients with HCC were obtained and analyzed to find the independent prognostic lncRNA. Based on the expression of lncRNA, we developed a risk score model, which was evaluated by survival analysis and ROC (receiver operating characteristic) curve. Enrichment analysis was performed to predict the possible role of the identified lncRNA in HCC prognosis.

Results

Four lncRNAs (RP11-322E11.5, RP11-150O12.3, AC093609.1, CTC-297N7.9) were found to be significantly and independently associated with survival of HCC patients. We used these four lncRNAs to construct a risk score model, which exhibited a strong ability to distinguish patients with significantly different prognosis (HR = 2.718, 95% CI [2.103–3.514], p = 2.32e−14). Similar results were observed in the subsequent stratification survival analysis for HBV infection status and pathological stage. The ROC curve also implied our risk score as a good indicator for 5-year survival prediction. Furthermore, enrichment analysis revealed that the four signature lncRNAs may be involved in multiple pathways related to tumorigenesis and prognosis.

Discussion

Our study recognized four lncRNAs to be significantly associated with prognosis of liver cancer, and could provide novel insights into the potential mechanisms of HCC progression. Additionally, CTC-297N7.9 may influence the downstream TMEM220 gene expression through cis-regualtion. Nevertheless, further well-designed experimental studies are needed to validate our findings.

Long non-coding RNA linc00673 regulated non-small cell lung cancer proliferation, migration, invasion and epithelial mesenchymal transition by sponging miR-150-5p

BACKGROUND

The function of a new long non-coding RNA linc00673 remains unclear. While identified as an oncogenic player in non-small cell lung cancer (NSCLC), linc00673 was found to be anti-oncogenic in pancreatic ductal adenocarcinoma (PDAC). However whether linc00673 regulated malignancy and epithelial mesenchymal transition (EMT) has not been characterized.

METHODS

Cell proliferation was assessed using CCK-8 and EdU assays, and cell migration and invasion were assessed using scratch assays and transwell invasion assays. Epithelial mesenchymal transition was examined using western blot, qRT-PCR and immunofluorescence staining. Interaction between miRNA and linc00673 was determined using luciferase reporter assays. In vivo experiments were performed to assess tumor formation. In addition, the expression data of NSCLC specimens of TCGA and patient survival data were utilized to explore the prognostic significance of linc00673.

RESULTS

In the present study, we found high linc00673 expression was associated with poor prognosis of NSCLC patients. In vitro experiments showed linc00673 knockdown reversed TGF-β induced EMT, and miR-150-5p was predicted to target linc00673 through bioinformatics tools. Overexpression of miR-150-5p suppressed lin00673's expression while inhibition of miR-150-5p led to significant upregulation of lin00673, suggesting that linc00673 could be negatively regulated by miR-150-5p, which was further confirmed by the inverse correlation between linc00673 and miR-150-5p in NSCLC patients' specimen. Furthermore, we proved that miR-150-5p could directly target linc00673 through luciferase assay, so linc00673 could sponge miR-150-5p and modulate the expression of a key EMT regulator ZEB1 indirectly. In addition, miR-150-5p inhibition abrogated linc00673 silence mediated proliferation, migration, invasion and EMT suppressing effect. Moreover, the inhibition of linc00673 significantly attenuated the tumorigenesis ability of A549 cells in vivo.

CONCLUSIONS

We validated linc00673 as a novel oncogenic lncRNA and demonstrated the molecular mechanism by which it promotes NSCLC, which will advance our understanding of its clinical significance.

LncRNA TUG1 influences papillary thyroid cancer cell proliferation, migration and EMT formation through targeting miR-145

LncRNA TUG1, a tumor oncogene associated with various human cancers, has been reported to be involved in regulating various cellular processes, such as proliferation, apoptosis and invasion through targeting multiple genes. However, its biological function in thyroid cancer cells has not been elucidated. The aim of this study is to measure TUG1 expression level and evaluate its function in thyroid cancer cells. LncRNA TUG1 expression levels in thyroid cancer tissues and three thyroid cancer cell lines (the ATC cell lines SW1736 and KAT18 and the FTC cell line FTC133) were assessed by qRT-PCR and compared with that of the human normal breast epithelial cell HGC-27. MTT assay, colony formation assay, transwell assay and western blot analysis were performed to assess the effects of TUG1 on proliferation, metastasis and EMT formation in thyroid cancer cells in vitro. Rescue assay was performed to further confirm that TUG1 contributes to the progression of thyroid cancer cells through regulating miR-145/ZEB1 signal pathway. LncRNA TUG1 was found to be up-regulated in thyroid cancer tissues and thyroid cancer cells compared with that in the human normal breast epithelial cell HGC-27. Increased lncRNA TUG1 expression was found to significantly promote tumor cell proliferation, and facilitate cell invasion, while down-regulated TUG1 could obviously inhibit cell proliferation, migration/invasion and reverse EMT to MET. These results indicated that TUG1 may contribute to the progression of thyroid cancer cells by function as a ceRNA competitive sponging miR-145, and that lncRNA TUG1 is associated with tumor progression in thyroid cancer cells.

LncRNAs as an intermediate in HPV16 promoting myeloid-derived suppressor cell recruitment of head and neck squamous cell carcinoma

The emerging evidence showed that long noncoding RNAs (lncRNAs) are involved in cell growth and apoptosis as well as cancer progression and metastasis of malignant tumor, however, limited data are available on the role of lncRNAs in human papillomavirus (HPV)-associated Head and neck squamous cell carcinomas (HNSCC). Here, we demonstrated that 23.98% of 196 HNSCC cases in Southwest China could be classified as HPV16 infection. The number of MDSCs in HPV-positive HNSCC was significantly higher than normal control, indicating that HPV infection may promote MDSCs aggregation. Then, we applied an array-based approach to monitor the lncRNA expression between HPV-positive HNSCC, HPV-negative HNSCC and normal oral mucous, and obtained 132 different lncRNAs in different HPV infected states of HNSCC. HOTAIR, PROM1, CCAT1, and MUC19 mRNA levels, determined by qRT-PCR were inversely correlated with MDSCs collection of HPV-associated HNSCC in 2 independent patient cohorts. The results may provide a rationale for the further evaluation of lncRNAs as a molecular target to elucidate the molecular mechanism of HPV promoting MDSCs collection of HNSCC.

Long non-coding RNA UBE2CP3 promotes tumor metastasis by inducing epithelial-mesenchymal transition in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a highly aggressive, solid malignancy that has a poor prognosis. Long non-coding RNAs (lncRNAs) have been found to be dysregulated in various cancers, including HCC. However, the molecular mechanism involving lncRNAs in HCC remains largely unknown. In this study, lncRNAs differentially expressed between HCC and corresponding non-cancerous tissue were identified by microarray analysis. A specific differentially expressed lncRNA UBE2CP3 (ubiquitin conjugating enzyme E2 C pseudogene 3) was identified. LncRNA UBE2CP3 was frequently up-regulated in HCC samples as assessed by quantitative real-time polymerase chain reaction (qRT-PCR) and in situ hybridization (ISH) experiments. Clinical data showed that high levels of lncRNA UBE2CP3 were correlated with poor prognosis in HCC patients. Functional studies demonstrated that over-expression of lncRNA UBE2CP3 promoted cell invasion and migration in vitro and in vivo. Mechanistically, enhanced expression of lncRNA UBE2CP3 increased the expression of Snail1 and N-cadherin, but decreased the expression of E-cadherin, thus promoting the process of epithelial to mesenchymal transition (EMT) and finally inducing cell invasion and migration. Furthermore, serum levels of lncRNA UBE2CP3 were increased in HCC patients and decreased after surgery. Our results suggest that lncRNA UBE2CP3 promotes the metastasis of HCC and that serum lncRNA UBE2CP3 may be a new biomarker for the diagnosis of HCC.

Long non-coding RNA CCAT1/miR-148a axis promotes osteosarcoma proliferation and migration through regulating PIK3IP1

Osteosarcoma is the most frequent type of malignant primary bone tumor. Although many efforts have been made, the survival rate of osteosarcoma still remains unsatisfied. Long non-coding RNAs (lncRNAs) have been demonstrated to be associated with many diseases including tumors, and involved in the regulation of a wide array of pathophysiological processes. Colon-cancer-associated transcript-1 (CCAT1) was first identified in colon cancer and has subsequently been reported to perform many functions in tumor progression. The present study aimed to comprehensively explore the biological functions of CCAT1 and its underlying mechanism in osteosarcoma cells. Our findings revealed that CCAT1 was upregulated in osteosarcoma tissues and cells, and was involved in the proliferation and migration of osteosarcoma via regulating miR-148a/phosphatidyl inositol 3-kinase interacting protein 1 (PIK3IP1) signal pathway.

Long Non-Coding RNAs: Key Regulators of Epithelial-Mesenchymal Transition, Tumour Drug Resistance and Cancer Stem Cells

Epithelial mesenchymal transition (EMT), the adoption by epithelial cells of a mesenchymal-like phenotype, is a process co-opted by carcinoma cells in order to initiate invasion and metastasis. In addition, it is becoming clear that is instrumental to both the development of drug resistance by tumour cells and in the generation and maintenance of cancer stem cells. EMT is thus a pivotal process during tumour progression and poses a major barrier to the successful treatment of cancer. Non-coding RNAs (ncRNA) often utilize epigenetic programs to regulate both gene expression and chromatin structure. One type of ncRNA, called long non-coding RNAs (lncRNAs), has become increasingly recognized as being both highly dysregulated in cancer and to play a variety of different roles in tumourigenesis. Indeed, over the last few years, lncRNAs have rapidly emerged as key regulators of EMT in cancer. In this review, we discuss the lncRNAs that have been associated with the EMT process in cancer and the variety of molecular mechanisms and signalling pathways through which they regulate EMT, and finally discuss how these EMT-regulating lncRNAs impact on both anti-cancer drug resistance and the cancer stem cell phenotype.

LncRNAs expression profiling in normal ovary, benign ovarian cyst and malignant epithelial ovarian cancer

Long noncoding RNA (lncRNA) has been recognized as a regulator of gene expression, and the dysregulation of lncRNAs is involved in the progression of many types of cancer, including epithelial ovarian cancer (EOC). To explore the potential roles of lncRNAs in EOC, we performed lncRNA and mRNA microarray profiling in malignant EOC, benign ovarian cyst and healthy control tissues. In this study, 663 transcripts of lncRNAs were found to be differentially expressed in malignant EOC compared with benign and normal control tissues. We also selected 18 altered lncRNAs to confirm the validity of the microarray analysis using quantitative real-time PCR (qPCR). Pathway and Gene Ontology (GO) analyses demonstrated that these altered transcripts were involved in multiple biological processes, especially the cell cycle. Furthermore, Series Test of Cluster (STC) and lncRNA-mRNA co-expression network analyses were conducted to predict lncRNA expression trends and the potential target genes of lncRNAs. We also determined that two antisense lncRNAs (RP11-597D13.9 and ADAMTS9-AS1) were associated with their nearby coding genes (FAM198B, ADAMTS9), which participated in cancer progression. This study offers helpful information to understand the initiation and development mechanisms of EOC.

Analysis of long noncoding RNA expression in hepatocellular carcinoma of different viral etiology

BACKGROUND

Dysregulation of long noncoding RNA (lncRNA) expression contributes to the pathogenesis of many human diseases, including liver diseases. Several lncRNAs have been reported to play a role in the development of hepatocellular carcinoma (HCC). However, most studies have analyzed lncRNAs only in hepatitis B virus (HBV)-related HCC or in a single group of HCC patients regardless of the viral etiology.

METHODS

To investigate whether lncRNAs are differentially expressed in HCC of different viral etiology, we profiled 101 disease-related lncRNAs, including 25 lncRNAs previously associated with HCC, in liver specimens obtained from well-characterized patients with HBV-, hepatitis C virus (HCV)-, or hepatitis D virus (HDV)-associated HCC.

RESULTS

We identified eight novel HCC-related lncRNAs that were significantly dysregulated in HCC tissues compared to their surrounding non-tumorous tissues. Some of these lncRNAs were significantly dysregulated predominantly in one specific hepatitis virus-related HCC, including PCAT-29 in HBV-related HCC, aHIF and PAR5 in HCV-related HCC, and Y3 in HDV-related HCC. Among the lncRNAs previously reported in HCC, we found that DBH-AS1, hDREH and hPVT1 were differentially expressed in HCC of different viral etiology.

CONCLUSIONS

Our study suggests that HCC of different viral etiology is regulated by different lncRNAs. The identification of lncRNAs unique to specific hepatitis virus-related HCC may provide new tools for improving the diagnosis of HCC and open new avenues for disease-specific therapeutic interventions.

Downregulation of ZEB2-AS1 decreased tumor growth and metastasis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) remains one of the most common types of cancer worldwide and prognosis remains poor. Previous studies have suggested that long non-coding RNAs (lncRNAs) may be key regulators of tumor development and progression in HCC. It has been determined that 61–72% of transcribed regions contain lncRNAs in the antisense orientation (aslncRNAs). However, the function of aslncRNAs in HCC remains to be elucidated. The present study investigated the function of the aslncRNA zinc finger E-box binding homeobox 2 antisense RNA 1 (ZEB2-AS1) in 40 HCC tissues and 5 different human HCC cell lines using reverse transcription-quantitative polymerase chain reaction. Additionally, the expression levels of ZEB2-AS1 were downregulated by transfection of small interfering RNAs (siRNAs) to determine whether ZEB2-AS1 is capable of affecting cell proliferation, invasion and metastasis by regulating ZEB2, vimentin, fibronectin, E-cadherin and N-cadherin expression levels. The results of the present study demonstrated that the expression levels of ZEB2-AS1 were greater in HCC tissues when compared with the adjacent normal tissues. Furthermore, ZEB2-AS1 expression was significantly associated with the size of the primary tumor, intrahepatic metastasis and tumor-node-metastasis stage. The Kaplan-Meier survival curves suggested that patients with high ZEB2-AS1 expression levels experienced the lowest overall and recurrence-free survival rates compared with those that had low expression levels. In addition, the current study demonstrated that the downregulation of ZEB2-AS1 was associated with decreased tumor growth and metastasis in HCC by the regulation of the expression levels of epithelial mesenchymal transition-induced markers. In conclusion, lncRNA ZEB2-AS1 may be used as a valuable biomarker in patients with HCC.

Role of epithelial to mesenchymal transition in hepatocellular carcinoma

The epithelial to mesenchymal transition (EMT) is a multistep biological process whereby epithelial cells change in plasticity by transient de-differentiation into a mesenchymal phenotype. EMT and its reversal, mesenchymal to epithelial transition (MET), essentially occur during embryogenetic morphogenesis and have been increasingly described in fibrosis and cancer during the last decade. In carcinoma progression, EMT plays a crucial role in early steps of metastasis when cells lose cell-cell contacts due to ablation of E-cadherin and acquire increased motility to spread into surrounding or distant tissues. Epithelial plasticity has become a hot issue in hepatocellular carcinoma (HCC), as strong inducers of EMT such as transforming growth factor-β are able to orchestrate both fibrogenesis and carcinogenesis, showing rising cytokine levels in cirrhosis and late stage HCC. In this review, we consider the significance of EMT-MET in malignant hepatocytes as well as changes in the plasticity of hepatic stellate cells for cellular heterogeneity of HCC, and further aim at explaining the current limiting insights into EMT by snapshot analyses of HCC tissues. Recent advances in the identification of clinically relevant mechanisms that impinge on important EMT-transcription factors, as well as on miRNAs causing EMT signatures and HCC progression are highlighted. In addition, we draw particular attention to framing EMT in the context of potential clinical relevance for HCC patients. We conclude that some aspects of EMT are still elusive and further studies are required to better link the clinical management of HCC with biomarkers and targeted therapies related to EMT.

Systemic transcriptome analysis of hepatocellular carcinoma

Liver cancer is one of the most common malignant tumors, and most of which is hepatocellular carcinoma (HCC). We aim to study the characteristic changes of numerous genes and their roles in HCC through systematical analysis of the characteristics of expression spectrum of HCC. Firstly, we made systematic clustering of the HCC samples according to the RNAseq data from TCGA (The Cancer Genome Atlas) and newly classified HCC. Then the characteristic genes in different molecular subtypes were found out and further analyzed combing with methylation and SNP 6.0 chip. Finally, these genes were subjected to do functional annotation and abnormal signaling pathways of HCC in various molecular subtypes and were screened out. There were 3843 differential genes screened; among which, 689 genes were enriched into 13 KEGG-related pathways, and the expression of 27 and 924 genes showed positive and negative correlation to methylation level, respectively, while the expression of 43 genes showed positive correlation to variation level of copy number. The methylation degree of ZSCAN18 may be considered as a marker for prognosis evaluation, and ABHD6 could be a potential anti-oncogene.

Analysis of long non-coding RNA expression profiles in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most aggressive and lethal malignancies. Long non-coding RNAs (lncRNAs) are a novel class of non-protein-coding transcripts that have been implicated in cancer biogenesis and prognosis. By repurposing microarray probes, we herein analysed the lncRNA expression profiles in two public PDAC microarray datasets and identified 34 dysregulated lncRNAs in PDAC. In addition, the expression of 6 selected lncRNAs was confirmed in Ren Ji cohort and pancreatic cell lines, and their association with 80 PDAC patients' clinicopathological features and prognosis was investigated. Results indicated that AFAP1-AS1, UCA1 and ENSG00000218510 might be involved in PDAC progression and significantly associated with overall survival of PDAC. UCA1 and ENSG00000218510 expression status may serve as independent prognostic biomarkers for overall survival of PDAC. Gene set enrichment analysis (GSEA) analysis suggested that high AFAP1-AS1, UCA1 and low ENSG00000218510 expression were correlated with several tumorigenesis related pathways. Functional experiments demonstrated that AFAP1-AS1 and UCA1 were required for efficient invasion and/or proliferation promotion in PDAC cell lines, while ENSG00000218510 acted the opposite. Our findings provide novel information on lncRNAs expression profiles which might be beneficial to the precise diagnosis, subcategorization and ultimately, the individualized therapy of PDAC.

A Long Noncoding RNA ZEB1-AS1 Promotes Tumorigenesis and Predicts Poor Prognosis in Glioma

Emerging studies show that long noncoding RNAs (lncRNAs) have important roles in carcinogenesis. lncRNA ZEB1 antisense 1 (ZEB1-AS1) is a novel lncRNA, whose clinical significance, biological function, and underlying mechanism remains unclear in glioma. Here, we found that ZEB1-AS1 was highly expressed in glioma tissues, being closely related to clinical stage of glioma. Moreover, patients with high ZEB1-AS1 levels had poor prognoses, with the evidence provided by multivariate Cox regression analysis indicating that ZEB1-AS1 expression could serve as an independent prognostic factor in glioma patients. Functionally, silencing of ZEB1-AS1 could significantly inhibit cell proliferation, migration, and invasion, as well as promote apoptosis. Knockdown of ZEB1-AS1 significantly induced the G0/G1 phase arrest and correspondingly decreased the percentage of S phase cells. Further analysis indicated that ZEB1-AS1 could regulate the cell cycle by inhibiting the expression of G1/S transition key regulators, such as Cyclin D1 and CDK2. Furthermore, ZEB1-AS1 functioned as an important regulator of migration and invasion via activating epithelial to mesenchymal transition (EMT) through up-regulating the expression of ZEB1, MMP2, MMP9, N-cadherin, and Integrin-β1 as well as decreasing E-cadherin levels in the metastatic progression of glioma. Additionally, forced down-regulation of ZEB1-AS1 could dramatically promote apoptosis by increasing the expression level of Bax and reducing Bcl-2 expression in glioma. Taken together, our data suggest that ZEB1-AS1 may serve as a new prognostic biomarker and therapeutic target of glioma.

A new avenue for obtaining insight into the functional characteristics of long noncoding RNAs associated with estrogen receptor signaling

Estrogen receptor signalling plays important regulatory roles in multiple mammalian physiological processes. Dysregulation of estrogen receptor (ER) expression and/or its associated signalling pathway is strongly associated with the development, progression, transition, and endocrine-resistance of breast cancer. Non-coding transcripts are essential regulators of almost every level of gene regulation. However, few long non-coding transcripts (lncRNAs) associated with the estrogen receptor signalling pathway have been well-described. We used array-based methods to identify 33 estrogen receptor agitation-related (ERAR) lncRNAs. A coding–non-coding gene co-expression network analysis suggested that 15 ERAR lncRNAs were associated with mitosis, DNA damage, and DNA repair. Kaplan–Meier analysis indicated that five ERAR lncRNAs selected using the Random Forest-Recursive Feature Elimination algorithm were significantly correlated with endocrine resistance-free survival and distant metastasis-free survival as well as disease free survival. Our results suggest that ERAR lncRNAs may serve as novel biomarkers for guiding breast cancer treatment and prognosis. Furthermore, our findings reveal a new avenue by which estrogen receptor signalling can be further explored.

Meta-analysis of the prognostic value of abnormally expressed lncRNAs in hepatocellular carcinoma

Many long noncoding RNAs (lncRNAs) have been reported to be abnormally expressed in hepatocellular carcinoma (HCC), and may have the potential to serve as prognostic markers. In this study, a meta-analysis was conducted to systematically evaluate the prognostic value of various lncRNAs in HCC. Eligible literatures were systematically collected from PubMed, Embase, Web of Science, and Cochrane Library (up to December 30, 2015). The main outcomes including overall survival, relapse-free survival, and disease-free survival were analyzed. Pooled hazard ratios (HRs) and 95% confidence intervals (95% CIs) were calculated using random- or fixed-effects models. A total of 2,991 patients with HCC in People’s Republic of China from 27 studies were included in the analysis. The level of lncRNAs showed a significant association with clinical outcomes. Abnormally elevated lncRNA transcription level predicted poor overall survival (HR: 1.68, 95% CI: 1.20–2.34, P=0.002; I²=75.5%, P=0.000) and relapse-free survival (HR: 2.08, 95% CI: 1.65–2.61, P<0.001; I²=24.0%, P=0.215), while no association was observed with disease-free survival of HCC patients (HR: 1.39, 95% CI: 0.51–3.78, P=0.524; I²=81.3%, P=0.005). Subgroup analysis further showed that lncRNA transcription level was significantly associated with tumor size (relative risk [RR]: 1.19, 95% CI: 1.01–1.39, P=0.035), microvascular invasion (RR: 1.44, 95% CI: 1.10–1.89, P=0.009), and portal vein tumor thrombus (RR: 1.50, 95% CI: 1.03–2.20, P=0.036). Publication bias and sensitivity analysis further confirmed the stability of our results. Our present meta-analysis indicates that abnormal lncRNA transcription level may serve as a promising indicator for prognostic evaluation of patients with HCC in People’s Republic of China.

Meta-analysis of the prognostic value of abnormally expressed lncRNAs in hepatocellular carcinoma

Many long noncoding RNAs (lncRNAs) have been reported to be abnormally expressed in hepatocellular carcinoma (HCC), and may have the potential to serve as prognostic markers. In this study, a meta-analysis was conducted to systematically evaluate the prognostic value of various lncRNAs in HCC. Eligible literatures were systematically collected from PubMed, Embase, Web of Science, and Cochrane Library (up to December 30, 2015). The main outcomes including overall survival, relapse-free survival, and disease-free survival were analyzed. Pooled hazard ratios (HRs) and 95% confidence intervals (95% CIs) were calculated using random- or fixed-effects models. A total of 2,991 patients with HCC in People's Republic of China from 27 studies were included in the analysis. The level of lncRNAs showed a significant association with clinical outcomes. Abnormally elevated lncRNA transcription level predicted poor overall survival (HR: 1.68, 95% CI: 1.20-2.34, P=0.002; I (2)=75.5%, P=0.000) and relapse-free survival (HR: 2.08, 95% CI: 1.65-2.61, P<0.001; I (2)=24.0%, P=0.215), while no association was observed with disease-free survival of HCC patients (HR: 1.39, 95% CI: 0.51-3.78, P=0.524; I (2)=81.3%, P=0.005). Subgroup analysis further showed that lncRNA transcription level was significantly associated with tumor size (relative risk [RR]: 1.19, 95% CI: 1.01-1.39, P=0.035), microvascular invasion (RR: 1.44, 95% CI: 1.10-1.89, P=0.009), and portal vein tumor thrombus (RR: 1.50, 95% CI: 1.03-2.20, P=0.036). Publication bias and sensitivity analysis further confirmed the stability of our results. Our present meta-analysis indicates that abnormal lncRNA transcription level may serve as a promising indicator for prognostic evaluation of patients with HCC in People's Republic of China.

Decreased expression of the long noncoding RNA LINC00261 indicate poor prognosis in gastric cancer and suppress gastric cancer metastasis by affecting the epithelial-mesenchymal transition

BACKGROUND

Recent evidence indicates that long noncoding RNAs (lncRNAs) play pivotal roles in the regulation of cellular processes and are found to be dysregulated in a variety of cancers. LINC00261 is an lncRNA that is aberrantly expressed in gastric cancer (GC). The clinical role of LINC00261 in GC and molecular mechanisms remains to be found.

METHODS

Real-time polymerase chain reaction (PCR) was used to examine LINC00261 expression in GC cell lines/tissues compared with normal epithelial cells/adjacent non-tumorous tissues. Gain and loss of function approaches were used to investigate the biological role of LINC00261 in GC cells. The effects of LINC00261 on cell viability were evaluated by MTT and colony formation assays. Wound healing assay, cell migration and invasion assays, and nude mice were used to examine the effects of LINC00261 on tumor cell metastasis in vitro and in vivo. Protein levels of LINC00261 targets were determined by western blot and immunohistochemistry.

RESULTS

LINC00261 was downregulated in GC cell lines and cancerous tissues, as compared with normal gastric epithelial cells and adjacent noncancerous tissue samples. Low LINC00261 expression was correlated with deeper tumor invasion (P < 0.001), higher tumor stage (P = 0.013), and lymphatic metastasis (P = 0.006). Univariate and multivariate analyses indicated that low LINC00261 expression predicted poor prognosis. Ectopic expression of LINC00261 impaired cell migration and invasion, leading to the inhibition of metastasis in vitro and in vivo. Knockdown of LINC00261 expression promoted cell migration and invasion in vitro. Overexpression of LINC00261 was found to play a key role in epithelial-mesenchymal transition (EMT) through the regulation of E-cadherin, N-cadherin, and Vimentin expression.

CONCLUSIONS

Low expression of the lncRNA LINC00261 occurs in GC and is associated with poor prognosis. LINC00261 suppresses GC metastasis by regulating EMT. Thus, LINC00261 plays an important role in the progression and metastasis of GC.

Nutritional Epigenetics and the Prevention of Hepatocellular Carcinoma with Bioactive Food Constituents

Hepatocellular carcinoma (HCC) is an aggressive and life-threatening disease often diagnosed at intermediate or advanced stages, which substantially limits therapeutic approaches to its successful treatment. This indicates that the prevention of HCC may be the most promising strategy in reducing its incidence and mortality. Emerging evidence indicates that numerous nutrients and nonnutrient dietary bioactive components can reduce the occurrence and/or delay the development of HCC through modifications of deregulated epigenetic mechanisms. This review examines the existing knowledge on the epigenetic mechanism-based studies in in vitro and in vivo models of HCC on the chemopreventive potential of epigenetic food components, including dietary methyl-group donors, epigallocatechin-3-gallate, sodium butyrate, resveratrol, curcumin, and sulforaphane, on liver carcinogenesis. Future direction and potential challenges in the effective use of bioactive food constituents in the prevention of HCC are highlighted and discussed.

Long non-coding RNA regulation of epithelial-mesenchymal transition in cancer metastasis

Metastasis is a multistep process starting with the dissemination of tumor cells from a primary site and ending with secondary tumor development in an anatomically distant location. The epithelial–mesenchymal transition (EMT), a process that endows epithelial tumor cells with mesenchymal properties including reduced adhesion and increased motility, is considered a critical step driving the early phase of cancer metastasis. Although significant progress has been made in understanding the molecular characteristics of EMT, the intracellular mechanisms driving transition through the various stages of EMT remain unclear. In recent years, an increasing number of studies have demonstrated the involvement of long non-coding RNAs (lncRNAs) in tumor metastasis through modulating EMT. LncRNAs and their associated signaling networks have now emerged as new players in the induction and regulation of EMT during metastasis. Here we summarize the recent findings and characterizations of several known lncRNAs involved in the regulation of EMT. We will also discuss the potential use of these lncRNAs as diagnostic and prognostic biomarkers as well as therapeutic targets to slow down or prevent metastatic spread of malignant tumors.

LINC01225 promotes occurrence and metastasis of hepatocellular carcinoma in an epidermal growth factor receptor-dependent pathway

The long noncoding RNAs (lncRNAs) have long been clarified to participate in hepatocellular carcinoma (HCC) as a biomarker. We carried out the present study in order to identify HCC-related lncRNAs and elucidate the functional roles in the development and progression of HCC. Our previous study has provided that LINC01225 may be an HCC-related gene. Here, we verified that LINC01225 was upregulated in HCC. Knockdown of LINC01225 resulted in inhibited cell proliferation and invasion with activated apoptosis and cell cycle arrest in vitro. Overexpression of LINC01225 in LINC01225 knockdown cells presented that attenuated cell proliferation and invasion were restored and enhanced. Subcutaneous and tail vein/intraperitoneal injection xenotransplantation model in vivo validated reduced tumor progression and metastasis. Investigation of mechanism found that LINC01225 could bind to epidermal growth factor receptor (EGFR) and increase the protein level of EGFR, and subsequently fine tune the EGFR/Ras/Raf-1/MEK/MAPK signaling pathway. Analysis with clinicopathological information suggested a high expression of LINC01225 is positively associated with poor prognosis. We also proved that LINC01225 was stably expressed in serum and can act as a novel biomarker in predicting the diagnosis of HCC. As a conclusion, LINC01225 plays a crucial role in HCC and can act as a biomarker for the diagnosis and prognosis of HCC.

Noncoding RNAs in Tumor Epithelial-to-Mesenchymal Transition

Epithelial-derived tumor cells acquire the capacity for epithelial-to-mesenchymal transition (EMT), which enables them to invade adjacent tissues and/or metastasize to distant organs. Cancer metastasis is the main cause of cancer-related death. Molecular mechanisms involved in the switch from an epithelial phenotype to mesenchymal status are complicated and are controlled by a variety of signaling pathways. Recently, a set of noncoding RNAs (ncRNAs), including miRNAs and long noncoding RNAs (lncRNAs), were found to modulate gene expressions at either transcriptional or posttranscriptional levels. These ncRNAs are involved in EMT through their interplay with EMT-related transcription factors (EMT-TFs) and EMT-associated signaling. Reciprocal regulatory interactions between lncRNAs and miRNAs further increase the complexity of the regulation of gene expression and protein translation. In this review, we discuss recent findings regarding EMT-regulating ncRNAs and their associated signaling pathways involved in cancer progression.

Expression profile analysis of long noncoding RNA in HER-2-enriched subtype breast cancer by next-generation sequencing and bioinformatics

BACKGROUND

Human epidermal growth factor receptor 2 (HER-2)-enriched subtype breast cancer is associated with a more aggressive phenotype and shorter survival time. Long non-coding RNAs (LncRNAs) have essential roles in tumorigenesis and occupy a central place in cancer progression. Notably, few studies have focused on the dysregulation of LncRNAs in the HER-2-enriched subtype breast cancer. In this study, we analyzed the expression profile of LncRNAs and mRNAs in this particular subtype of breast cancer.

METHODS

Seven pairs of HER-2-enriched subtype breast cancer and normal tissue were sequenced. We screened out differently expressed genes and measured the correlation of the expression levels of dysregulated LncRNAs and HER-2 by Pearson's correlation coefficient analysis. Gene ontology analysis and pathway analysis were used to understand the biological roles of these differently expressed genes. Pathway act network and coexpression network were constructed.

RESULTS

More than 1,300 LncRNAs and 2,800 mRNAs, which were significantly differently expressed, were identified. Among these LncRNAs, AFAP1-AS1 was the most dysregulated LncRNA, while ORM2 was the most dysregulated mRNA. LOC100288637 had the highest positive correlation coefficient of 0.93 with HER-2, while RPL13P5 had the highest negative correlation coefficient of -0.87. The pathway act network showed that MAPK signaling pathway, PI3K-Akt signaling pathway, metabolic pathways, cell cycle, and regulation of actin cytoskeleton were highly related with HER-2-enriched subtype breast cancer. Coexpression network recognized LINC00636, LINC01405, ADARB2-AS1, ST8SIA6-AS1, LINC00511, and DPP10-AS1 as core genes.

CONCLUSION

These results analyze the functions of LncRNAs and provide useful information for exploring candidate therapeutic targets and new molecular biomarkers for HER-2-enriched subtype breast cancer.

The role of the oncofetal H19 lncRNA in tumor metastasis: orchestrating the EMT-MET decision

Long non-coding RNA (lncRNA) genes are emerging as key players in the metastatic cascade. Current evidence indicate that H19 lncRNA and the microRNA(miRNA) miR-675, which is processed from it, play crucial roles in metastasis, through the regulation of critical events specifically the epithelial to mesenchymal (EMT) and the mesenchymal to epithelial transitions (MET). This review summarizes recent mechanistic pathways and tries to put together seemingly conflicting data from different reports under one proposed general scheme underlying the various roles of H19/miR-675 in the metastatic cascade. We propose several approaches to harnessing this knowledge for translational medicine.