Long non-coding RNAs: novel prognostic biomarkers for liver metastases in patients with early stage colorectal cancer. Oncotarget. 2016;7:50428-50436. [PMID: 27391432 PMCID: PMC5226593 DOI: 10.18632/oncotarget.10416]

Harnessing the supremacy of MEG3 LncRNA to defeat gastrointestinal malignancies

Evidence suggests that long non-coding RNAs (lncRNAs) play a pivotal role in the carcinogenesis and progression of various human malignancies including gastrointestinal malignancies. This comprehensive review reports the functions and mechanisms of the lncRNA maternally expressed gene 3 (MEG3) involved in gastrointestinal malignancies. It summarizes its roles in mediating the regulation of cellular proliferation, apoptosis, migration, invasiveness, epithelial-to-mesenchymal transition, and drug resistance in several gastrointestinal cancers such as colorectal cancer, gall bladder cancer, pancreatic cancer, gastric cancer, esophageal cancer, cholangiocarcinoma, gastrointestinal stromal tumors and most importantly, hepatocellular carcinoma. In addition, the authors briefly highlight its implicated mechanistic role and interactions with different non-coding RNAs and oncogenic signaling cascades. This review presents the rationale for developing non coding RNA-based anticancer therapy via harnessing the power of MEG3 in gastrointestinal malignancies.

LINC00858 facilitates formation of hepatic metastases from colorectal cancer via regulating the miR-132-3p/IGF2BP1 axis

Hepatic metastasis is a major cause of colorectal cancer (CRC)-related deaths. Presently, the role of long non-coding RNAs (lncRNAs) in hepatic metastases from CRC is elusive. We dissected possible interplay between LINC00858/miR-132-3p/IGF2BP1 via bioinformatics approaches. Subsequently we analyzed mRNA expression of LINC00858, miR-132-3p and IGF2BP1 through qRT-PCR. Western blot was used to detect protein expression of IGF2BP1. RNA immunoprecipitation chip and dual-luciferase assay validated interaction between LINC00858 and miR-132-3p, as well as miR-132-3p and IGF2BP1. Cell viability, invasion, and migration were examined via CCK-8, colony formation, transwell and wound healing assays. Effect of LINC00858 on CRC hepatic metastases was validated via in vivo assay. Upregulated LINC00858 and IGF2BP1, and downregulated miR-132-3p were predicted in tumor tissues of patients with hepatic metastases from CRC. There were targeting relationships between LINC00858 and miR-132-3p, as well as miR-132-3p and IGF2BP1. Besides, LINC00858 facilitated progression of CRC cells. Rescue assay suggested that silencing LINC00858 suppressed CRC cell progression, while further silencing miR-132-3p or overexpressing IGF2BP1 reversed such effects. LINC00858 could facilitate CRC tumor growth and hepatic metastases. LINC00858 induced CRC hepatic metastases via regulating miR-132-3p/ IGF2BP1, and this study may deliver a new diagnostic marker for the disease.

Intracellular and extracellular factors of colorectal cancer liver metastasis: a pivotal perplex to be fully elucidated

Metastasis is the leading cause of death in colorectal cancer (CRC) patients, and the liver is the most common site of metastasis. Tumor cell metastasis can be thought of as an invasion-metastasis cascade and metastatic organotropism is thought to be a process that relies on the intrinsic properties of tumor cells and their interactions with molecules and cells in the microenvironment. Many studies have provided new insights into the molecular mechanism and contributing factors involved in CRC liver metastasis for a better understanding of the organ-specific metastasis process. The purpose of this review is to summarize the theories that explain CRC liver metastasis at multiple molecular dimensions (including genetic and non-genetic factors), as well as the main factors that cause CRC liver metastasis. Many findings suggest that metastasis may occur earlier than expected and with specific organ-anchoring property. The emergence of potential metastatic clones, the timing of dissemination, and the distinct routes of metastasis have been explained by genomic studies. The main force of CRC liver metastasis is also thought to be epigenetic alterations and dynamic phenotypic traits. Furthermore, we review key extrinsic factors that influence CRC cell metastasis and liver tropisms, such as pre-niches, tumor stromal cells, adhesion molecules, and immune/inflammatory responses in the tumor microenvironment. In addition, biomarkers associated with early diagnosis, prognosis, and recurrence of liver metastasis from CRC are summarized to enlighten potential clinical practice, including some markers that can be used as therapeutic targets to provide new perspectives for the treatment strategies of CRC liver metastasis.

LncRNA GAS5 Suppresses Colorectal Cancer Progress by Target miR-21/LIFR Axis

GAS5 is abnormally high in colorectal cancer tissues, which is a specific expression of lncRNA in colorectal cancer (CRC). Nevertheless, its biological function in CRC has not been elucidated. The abnormal high expression of GAS5 in CRC is the specific expression of lncRNA in CRC. The purpose of our study is to explore the effect of GAS5 on CRC and its mechanism. The expression of GAS5 in 53 paired normal and colorectal cancer tissues and colorectal cancer cell lines was detected by real-time PCR. The biological effects of GAS5, miR-21, and LIFR were measured by functional assays, including wound healing, transwell assays, and in vivo assays. We ensured the carcinogenesis role of GAS5 in CRC in the xenograft nude model. The dual-luciferase reporter assay system and chromatin immunoprecipitation method were used for target evaluation and Western blot for verification. GAS5 was significantly decreased in tumor tissues and CRC cells, and the low expression of CAS5 in CRC promoted tumor metastasis and decreased the survival of patients. GAS5 knockdown increases the cell viability, inhibits apoptosis, and promotes migration. Xenografted tumors in nude mice studies showed that GAS5 knockdown promoted tumor growth and caused worse lesions in colorectal. Furthermore, GAS5 increases the expression level of target gene LIFR to promote the apoptosis of CRC cells by binding to miR-21. Our study revealed that a novel pathway about lncRNA GAS5 inhibited the proliferation and metastasis of CRC cells by targeting miR-21/LIFR which provides a new strategy to treat CRC.

Long non-coding RNAs involved in different steps of cancer metastasis

Non-proteincoding transcripts bearing 200 base pairs known as long non-coding RNAs (lncRNAs) play a role in a variety of molecular mechanisms, including cell differentiation, apoptosis and metastasis. Previous studies have suggested that frequently dysregulated lncRNAs play a crucial role in various aspects of cancer metastasis. Metastasis is the main leading cause of death in cancer. The role of lncRNAs in different stages of metastasis is the subject of this review. Based on in vitro and in vivo investigations on metastasis, we categorized lncRNAs into distinct stages of metastasis including angiogenesis, invasion, intravasation, survival in circulation, and extravasation. The involvement of lncRNAs in angiogenesis and invasion has been extensively studied. Here, we comprehensively discuss the role and functions of these lncRNAs with a particular focus on the molecular mechanisms.

Metastatic colorectal cancer: Perspectives on long non-coding RNAs and promising therapeutics

Metastatic colorectal cancer (mCRC) has long been lethal despite the continuous efforts of researchers worldwide to discover and improve therapeutic regimens. Thanks to the emergence of long non-coding RNAs (lncRNAs), which has strongly reshaped our inherent perspectives on the pathophysiological patterns of disease, research in the field has been reinvigorated. Here, we focus on current understanding of the modes of action of lncRNAs, and review their regulatory roles in metastatic colorectal cancer, and discuss correlated potential lncRNA-based therapeutics. All of the discussed studies share clear and promising perspectives on future diagnostic and therapeutic remedies for metastatic colorectal cancer.

Decoding competing endogenous RNA networks for cancer biomarker discovery

Crosstalk between competing endogenous RNAs (ceRNAs) is mediated by shared microRNAs (miRNAs) and plays important roles both in normal physiology and tumorigenesis; thus, it is attractive for systems-level decoding of gene regulation. As ceRNA networks link the function of miRNAs with that of transcripts sharing the same miRNA response elements (MREs), e.g. pseudogenes, competing mRNAs, long non-coding RNAs, and circular RNAs, the perturbation of crucial interactions in ceRNA networks may contribute to carcinogenesis by affecting the balance of cellular regulatory system. Therefore, discovering biomarkers that indicate cancer initiation, development, and/or therapeutic responses via reconstructing and analyzing ceRNA networks is of clinical significance. In this review, the regulatory function of ceRNAs in cancer and crucial determinants of ceRNA crosstalk are firstly discussed to gain a global understanding of ceRNA-mediated carcinogenesis. Then, computational and experimental approaches for ceRNA network reconstruction and ceRNA validation, respectively, are described from a systems biology perspective. We focus on strategies for biomarker identification based on analyzing ceRNA networks and highlight the translational applications of ceRNA biomarkers for cancer management. This article will shed light on the significance of miRNA-mediated ceRNA interactions and provide important clues for discovering ceRNA network-based biomarker in cancer biology, thereby accelerating the pace of precision medicine and healthcare for cancer patients.

Functional roles of lncRNAs in the pathogenesis and progression of cancer

Long noncoding RNAs (lncRNAs) act as regulators of gene expression and pivotal transcriptional regulators in cancer cells via diverse mechanisms. lncRNAs involves a variety of pathological and biological activities, such as apoptosis, cell proliferation, metastasis, and invasion. By using microarray and RNA sequencing, it was identified that dysregulation of lncRNAs affects the tumorigenesis process. Taken together, these lncRNAs are putative biomarker and therapeutic target in human malignancies. In this review, I discuss the latest finding regarding the dysregulation of some important lncRNAs and their diverse mechanisms of these lncRNAs in the pathogenesis and progression of certain cancers; also, I summarize the possible roles of lncRNAs in clinical application for diagnosis and prognosis of cancer.

Clinicopathological Significance of Long Non-Coding RNA GHET1 in Human Cancers: A Meta-Analysis

Introduction:

Cancer is considered as the main public health problem and the second leading cause of morbidity and mortality worldwide. Numerous environmental-lifestyle related risk factors account for around one-third of cancer deaths. Recently, the key role of lncRNAs has been widely investigated in a variety of disorders, including cancer. The lncRNA GHET1 has been considered as an essential oncogenic lncRNA in many types of human cancers. Clinical investigations indicated that expression of lncRNA GHET1 is correlated with clinicopathological characteristics in cancer. This metaanalysis investigated the correlation between the lncRNA GHET1 expression and clinicopathological features in different types of cancers.

Materials and Methods:

Comprehensive literature searches in PubMed, Scopus, and Web of Knowledge were conducted up to April 11, 2019. Sixteen studies were included in this meta-analysis. All statistical analyses were conducted using Stata software, version 12.0.

Results:

The pooled OR and 95%CIs of the sixteen relevant studies showed that over expression of lncRNA GHET1 was associated with tumor-size ≥5 cm (OR= 2.51, 95% CI: 1.89-3.33, p=0.00, I2=38.30%), positive lymph node metastasis (OR= 2.83, 95% CI: 1.78-4.52, p=0.00, I2=45.60%), advanced tumor stage (OR= 3.92, 95% CI: 2.97-5.19, p=0.00, I2=0.00%), positive distant metastasis (OR= 5.74, 95% CI: 2.58-12.77, p=0.00, I2=0.00%), advanced tumor status (OR= 2.97, 95% CI: 1.40- 6.29, p=0.01, I2=34.70%), and positive vascular invasion (OR= 2.69, 95% CI: 1.61-4.50, p=0.00, I2=29.20%).

Conclusion:

Taken together, the current study demonstrated that overexpression of lncRNA GHET1 is significantly associated with clinicopathological features in human cancers. Our results suggested that lncRNA GHET1 can be utilized as a prognostic biomarker in human cancer.

Mechanisms of long non-coding RNA function in colorectal cancer tumorigenesis

Colorectal cancer (CRC) is one of the most common cancers globally. Although a variety of CRC screening methods have been developed, many patients are diagnosed at advanced stages of CRC with tumor invasion and distance metastasis. Several studies have suggested the long noncoding RNAs (lncRNAs) as one of the main contributors in CRC tumorigenesis, although the exact underlying mechanism of lncRNAs in CRC is still unknown. Numerous studies have indicated aberrant expression of lncRNAs in CRC through different modes of action such as cell proliferation, apoptosis, cell cycle, DNA repair response, drug-resistance, migration, and metastasis. Furthermore, lncRNA polymorphisms can influence the risk of CRC development. Accordingly, lncRNAs can be served as promising diagnostic or prognostic biomarkers and also desired therapeutic targets affecting the outcome of patients with CRC. In this review, we summarized the updated and novel evidence that identifies different roles of lncRNAs in the tumorigenesis of CRC.

Long Non-coding RNA MEG3 Activated by Vitamin D Suppresses Glycolysis in Colorectal Cancer via Promoting c-Myc Degradation

Colorectal cancer (CRC), a common tumor, is characterized by a high mortality rate. Long non-coding RNA maternally expressed gene 3 (MEG3) serves a regulatory role in the carcinogenesis and progression of several types of cancer; however, its role in CRC remains largely unknown. The aim of this study was to explore the regulatory role and mechanism(s) of MEG3 in CRC. The Warburg effect or aerobic glycolysis is characteristic of the metabolism of tumor cells. To determine the effect of MEG3 on glycolysis of CRC cells, we used an XF analyzer to perform glycolysis stress test assays and found that overexpression of MEG3 significantly inhibited glycolysis, glycolytic capacity, as well as lactate production in CRC cells, whereas knockdown of MEG3 produced the opposite effect. Mechanistically, overexpression of MEG3 induced ubiquitin-dependent degradation of c-Myc and inhibited c-Myc target genes involved in the glycolysis pathway such as lactate dehydrogenase A, pyruvate kinase muscle 2, and hexokinase 2. Moreover, we found that MEG3 can be activated by vitamin D and vitamin D receptor (VDR). Clinical data demonstrated that MEG3 was positively associated with serum vitamin D concentrations in patients with CRC. We found that 1,25(OH)₂D₃ treatment increased MEG3 expression, and knockdown of VDR abolished the effect of MEG3 on glycolysis. These results indicate that vitamin D-activated MEG3 suppresses aerobic glycolysis in CRC cells via degradation of c-Myc. Thus, vitamin D may have therapeutic value in the treatment of 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.

LncRNA MEG3 acts a biomarker and regulates cell functions by targeting ADAR1 in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is the third most prevalent malignancy and has the fourth highest global cancer mortality rate. Early diagnosis and prompt medical attention can improve quality of life and the prognosis of CRC patients. Accumulating evidence reveals that long non-coding RNAs (lncRNAs) function as oncogenes or anti-oncogenes, as well as biomarkers in various cancers.

AIM

To investigate the levels and molecular mechanism of the lncRNA maternally expressed gene 3 (MEG3) in CRC.

METHODS

The levels of lncRNA MEG3 in CRC tissue, serum and cell line samples were explored via qRT-PCR. The relationship between MEG3 levels and clinicopathological features in CRC was investigated. The diagnostic and prognostic values of serum MEG3 levels were analyzed with ROC curves and Kaplan‑Meier survival curves, respectively.

RESULTS

Significant decreased levels of MEG3 existed in CRC tissue, cell lines and serum. CRC patients with down-regulated serum MEG3 levels had larger tumor sizes, and advanced clinical stages. The sensitivity and specificity of serum MEG3 levels in CRC detection was 0.667 and 0.875, respectively. Tumor size, T stages, and serum MEG3 levels are indie factors that produce an effect on CRC patients' prognosis. Kaplan‑Meier survival curves suggested that CRC patients with high levels of MEG3 had a remarkably better overall survival rate.

CONCLUSION

LncRNA MEG3 is down-regulated in CRC, and regulates cell functions by targeting adenosine deaminase’s effect on RNA 1 in CRC.

Molecular mechanisms of long noncoding RNAs-mediated cancer metastasis

Cancer metastasis is a multistep process that requires cancer cells to leave the primary site, survive in the blood stream, and finally colonize at a distant organ. It is the major cause of cancer morbidity and mortality. The organ-specific colonization requires close interaction and communication between cancer cells and host organs. Noncoding RNAs represent the majority of the transcriptome, with long noncoding RNAs (lncRNAs) making up a significant proportion. It has been suggested that lncRNAs play a key role in all stages of tumorigenesis and metastasis. This review will provide an overview of how lncRNAs are involved in cancer cell colonization in specific organ sites and the underlying mechanisms as well as therapeutic strategies.

From biomarkers to therapeutic targets-the promises and perils of long non-coding RNAs in cancer

Biomarker-driven personalized cancer therapy is a field of growing interest, and several molecular tests have been developed to detect biomarkers that predict, e.g., response of cancers to particular therapies. Identification of these molecules and understanding their molecular mechanisms is important for cancer prognosis and the development of therapeutics for late stage diseases. In the past, significant efforts have been placed on the discovery of protein or DNA-based biomarkers while only recently the class of long non-coding RNA (lncRNA) has emerged as a new category of biomarker. The mammalian genome is pervasively transcribed yielding a vast amount of non-protein-coding RNAs including lncRNAs. Hence, these transcripts represent a rich source of information that has the potential to significantly contribute to precision medicine in the future. Importantly, many lncRNAs are differentially expressed in carcinomas and they are emerging as potent regulators of tumor progression and metastasis. Here, we will highlight prime examples of lncRNAs that serve as marker for cancer progression or therapy response and which might represent promising therapeutic targets. Furthermore, we will introduce lncRNA targeting tools and strategies, and we will discuss potential pitfalls in translating these into clinical trials.

Growth arrest specific transcript 5 in tumorigenesis process: An update on the expression pattern and genomic variants

Growth arrest-specific 5 (GAS5) is a long non-coding RNA (lncRNA) with diverse functions in regulation of gene expression. Most studies have reported a role for this lncRNA in induction of cell apoptosis and suppression of tumorigenesis process. Although few studies demonstrated up-regulation of this lncRNA in tumor tissues compared to non-tumor tissues of the same origin, the results of in vitro functional studies mostly support the tumor suppressor role for GAS5. A number of recent studies have also shown associations between genomic variants of this gene and risk of cancer in some populations. The role of this lncRNA in modulation of response to anti-cancer regimens has been verified through both in vitro and clinical studies. Taken together, this lncRNA is a putative biomarker and therapeutic target in human malignancies.

LEF1-AS1 contributes to proliferation and invasion through regulating miR-544a/ FOXP1 axis in lung cancer

Long non-coding RNAs (lncRNAs) are increasingly recognized as important regulators in tumor development. This study aims to investigate the potential role oflncRNALEF1-AS1, in the progression of lung cancer. Quantitative real-time PCR (qRT-PCR) and western blot assays showed that LEF1-AS1 was upregulated while miR-544a was downregulated in lung cancer specimens and cells. Overexpression of LEF1-AS1 led to the enhancement of cell proliferation and invasion, revealed by CCK-8 assay and transwell assay. A negative correlation was found between LEF1-AS1 and miR-544a. BLAST analysis and dual-luciferase assay confirmed that FOXP1 is a downstream effector of miR-544a. Therefore, the LEF1-AS1/miR-544a/FOXP1 axis is an important contributor to lung cancer progression. Collectively, our novel data uncovers a new mechanism that governs tumor progression in lung cancer and provides new targets that may be used for disease monitoring and therapeutic intervention of lung cancer.

MEG3, as a Competing Endogenous RNA, Binds with miR-27a to Promote PHLPP2 Protein Translation and Impairs Bladder Cancer Invasion

Muscle-invasive and metastatic bladder cancer have an extremely poor 5-year survival rate of 5%. In comparison, all other bladder cancers (BCs) have a 5-year survival rate of 77%. This striking contrast indicates that one of the therapeutic kernels for bladder cancer is to elucidate the molecular mechanisms underlying its invasiveness and metastasis. In the current study, we demonstrated that maternally expressed gene 3 (MEG3) is significantly downregulated in human invasive bladder cancers in comparison to non-invasive bladder cancers, and that ectopic expression of MEG3 dramatically inhibits the invasiveness of human bladder cancer cells. Consistently, ectopic expression of MEG3 also attenuates metastatic ability of T24T cells, a cell line derived from T24 cells, in the lungs of nude mice. Our mechanistic studies reveal that MEG3, as a ceRNA, inhibits the invasiveness of human bladder cancer cells via negative regulation of c-Myc by competing with PHLPP2 mRNA for miR-27a. These findings not only provide a novel insight into understanding the mechanisms behind the MEG3 inhibition of bladder cancer cell invasion, but also reveal the potential for use of MEG3 as a tool for the prevention and therapy of invasive bladder cancer.

Z Probe, An Efficient Tool for Characterizing Long Non-Coding RNA in FFPE Tissues

Formalin-fixed paraffin embedded (FFPE) tissues are a valuable resource for biomarker discovery in order to understand the etiology of different cancers and many other diseases. Proteins are the biomarkers of interest with respect to FFPE tissues as RNA degradation is the major challenge in these tissue samples. Recently, non-protein coding transcripts, long non-coding RNAs (lncRNAs), have gained significant attention due to their important biological actions and potential involvement in cancer. RNA sequencing (RNA-seq) or quantitative reverse transcription-polymerase chain reaction (qRT-PCR) are the only validated methods to evaluate and study lncRNA expression and neither of them provides visual representation as immunohistochemistry (IHC) provides for proteins. We have standardized and are reporting a sensitive Z probe based in situ hybridization method to visually identify and quantify lncRNA in FFPE tissues. This assay is highly sensitive and identifies transcripts visible within different cell types and tumors. We have detected a scarcely expressed tumor suppressor lncRNA NRON (non-coding repressor of nuclear factor of activated T-cells (NFAT)), a moderately expressed oncogenic lncRNA UCA1 (urothelial cancer associated 1), and a highly studied and expressed lncRNA MALAT1 (metastasis associated lung adenocarcinoma transcript 1) in different cancers. High MALAT1 staining was found in colorectal, breast and pancreatic cancer. Additionally, we have observed an increase in MALAT1 expression in different stages of colorectal cancer.

Roles of long noncoding RNAs in colorectal cancer metastasis

Colorectal cancer (CRC) is the 3^rd most common malignancies worldwide. Metastasis is responsible for more than 90% CRC patients' death. Long noncoding RNAs (lncRNAs) are an important class of transcribed RNA molecules greater than 200 nucleotides in length. With the development of whole genome sequencing technologies, they have been gained more attention. Accumulating evidences suggest that abnormal expression of lncRNAs in diverse diseases are involved in various biological functions such as proliferation, apoptosis, metastasis and differentiation by acting as epigenetic, splicing, transcriptional or post-transcriptional regulators. Aberrant expression of lncRNAs has also been found in CRC. Besides, recent studies have indicated that lncRNAs play important roles in tumourigenesis and cancer metastasis. They participate in the process of metastasis by activing or inhibiting the metastatic pathways. However, their functions on the development of cancer metastasis are poorly understood. In this review, we highlight the findings of roles for lncRNAs in CRC metastasis and review the metastatic pathways of lncRNAs leading to cancer metastasis in CRC, including escape of apoptosis, epithelial-mesenchymal transition (EMT), angiogenesis and invasion, migration and proliferation. Furthermore, we also discuss the potential clinical application of lncRNAs in CRC as diagnostic markers and therapeutic targets.

Protein-coding genes combined with long noncoding RNA as a novel transcriptome molecular staging model to predict the survival of patients with esophageal squamous cell carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is the predominant subtype of esophageal carcinoma in China. This study was to develop a staging model to predict outcomes of patients with ESCC.

METHODS

Using Cox regression analysis, principal component analysis (PCA), partitioning clustering, Kaplan-Meier analysis, receiver operating characteristic (ROC) curve analysis, and classification and regression tree (CART) analysis, we mined the Gene Expression Omnibus database to determine the expression profiles of genes in 179 patients with ESCC from GSE63624 and GSE63622 dataset.

RESULTS

Univariate cox regression analysis of the GSE63624 dataset revealed that 2404 protein-coding genes (PCGs) and 635 long non-coding RNAs (lncRNAs) were associated with the survival of patients with ESCC. PCA categorized these PCGs and lncRNAs into three principal components (PCs), which were used to cluster the patients into three groups. ROC analysis demonstrated that the predictive ability of PCG-lncRNA PCs when applied to new patients was better than that of the tumor-node-metastasis staging (area under ROC curve [AUC]: 0.69 vs. 0.65, P < 0.05). Accordingly, we constructed a molecular disaggregated model comprising one lncRNA and two PCGs, which we designated as the LSB staging model using CART analysis in the GSE63624 dataset. This LSB staging model classified the GSE63622 dataset of patients into three different groups, and its effectiveness was validated by analysis of another cohort of 105 patients.

CONCLUSIONS

The LSB staging model has clinical significance for the prognosis prediction of patients with ESCC and may serve as a three-gene staging microarray.

MEG3 Activated by Vitamin D Inhibits Colorectal Cancer Cells Proliferation and Migration via Regulating Clusterin

The long non-coding RNA maternally expressed gene 3 (MEG3) is frequently dysregulated in human cancers; however, its roles in colorectal cancer (CRC) development are largely unknown. Here, we reported that MEG3 was down-regulated in CRC tissues and CRC patients with lower MEG3 showed poorer overall survival and disease-free survival than those with higher MEG3 level. MEG3 over-expression represses CRC cells proliferation and migration in vivo and in vitro, while MEG3 knockdown leads to the enhanced proliferation and metastasis of CRC cells. In CRC cells, MEG3 over-expression is related to decreased Clusterin mRNA and the corresponding protein levels, and it also directly binds to Clusterin protein through its 732–1174 region. In further, Clusterin over-expression rescues the compromised abilities of proliferation and metastasis induced by MEG3 over-expression, suggesting that MEG3 inhibits the CRC progression through regulating the Clusterin activities. Additionally, we found that 1α,25-(OH)₂D and vitamin D receptor (VDR) stimulate MEG3 expression in CRC cells through directly binding to its promoter. These results suggested that MEG3 functions as a tumor suppressor in CRC via regulating the Clusterin activities and may underlie the anticancer activities of vitamin D on CRC cells. The VDR/MEG3/Clusterin signaling pathway may serve as potential therapeutic targets and prognosis biomarkers for CRC patients in future.

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MEG3 serves as a novel CRC prognosis biomarker and a potential therapeutic target.

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MEG3 over-expression represses CRC cells proliferation and metastatic features.

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MEG3 has a role in Clusterin expression and activity down-regulation at transcriptional and post-transcriptional levels.

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VDR activated MEG3 expression via directly binding to MEG3 promoter.

Identification and validation a TGF-β-associated long non-coding RNA of head and neck squamous cell carcinoma by bioinformatics method

BACKGROUND

The role of transforming growth factorβ (TGF-β)-induced tumor progression in advanced malignancy is well established, but the involvement of long non-coding RNAs (lncRNAs) in TGF-β signaling remains unclear. This study aimed to identify TGF-β-associated lncRNAs in head and neck squamous cell carcinoma (HNSCC).

METHODS

Expression profiling of lncRNAs was obtained using Gene Expression Omnibus and The Cancer Genome Atlas. Real-time quantitative PCR was used to analyze the expression of EPB41L4A-AS2 in HNSCC cell line. We used bioinformatics resources (DAvID) to conduct Gene Ontology biological processes and KEGG pathways at the significant level. Wound healing assay, cell migration and invasion assays, were used to examine the effects of EPB41L4A-AS2 on tumor cell metastasis in vivo. Protein levels of EPB41L4A-AS2 targets were determined by western blot.

RESULTS

A novel TGF-β-associated lncRNA, EPB41L4A-AS2, was found downregulated by TGF-β and associated with invasion and metastasis. The relationship of EPB41L4A-AS2 with the clinicopathological features and prognosis of HNSCC patients was evaluated. Bioinformatic analyses revealed that EPB41L4A-AS2 may be involved in processes associated with the tumor-associated signaling pathway, especially the TGF-β signaling pathway. Furthermore, a TGF-β-induced epithelial-to-mesenchymal transition (EMT) model was established. Low EPB41L4A-AS2 expression was determined, and overexpression of this gene inhibited cell migration and invasion in the EMT model. Moreover, EPB41L4A-AS2 suppressed TGFBR1 expression.

CONCLUSIONS

EPB41L4A-AS2 might serve as a negative regulator of TGF-β signaling and as an effective prognostic biomarker and important target in anti-metastasis therapies of HNSCC patients.

Long non-coding RNAs: a rising biotarget in colorectal cancer

Colorectal cancer (CRC) is a common gastrointestinal cancer, with a high incidence and high mortality. Long non-coding RNAs (lncRNAs) are involved in the development, invasion and metastasis, early diagnosis, prognosis, the chemoresistance and radioresistance of CRC through interference with mRNA activity, directly combining with proteins to regulate their activity or alter their localization, influencing downstream gene expression by inhibiting RNA polymerase and regulating gene expression as competing endogenous RNAs. Recent progress in next generation sequencing and transcriptome analysis has revealed that tissue and cancer-type specific lncRNAs could be useful prognostic markers. Here, the CRC-associated lncRNAs from recent studies until October 2016 are reviewed and multiple studies that have confirmed CRC-associated lncRNAs are summarized. This review may be helpful in understanding the overall relationships between the lncRNAs involved in CRC.

Protein-coding genes, long non-coding RNAs combined with microRNAs as a novel clinical multi-dimension transcriptome signature to predict prognosis in ovarian cancer

Ovarian cancer is prevalent in women which is usually diagnosed at an advanced stage with a high mortality rate. The aim of this study is to investigate protein-coding gene, long non-coding RNA, and microRNA associated with the prognosis of patients with ovarian serous carcinoma by mining data from TCGA (The Cancer Genome Atlas) public database. The clinical data of ovarian serous carcinoma patients was downloaded from TCGA database in September, 2016. The mean age and survival time of 407 patients with ovarian serous carcinoma were 59.71 ± 11.54 years and 32.98 ± 26.66 months. Cox's proportional hazards regression analysis was conducted to analyze genes that were significantly associated with the survival of ovarian serous carcinoma patients in the training group. Using the random survival forest algorithm, Kaplan-Meier and ROC analysis, we kept prognostic genes to construct the multi-dimensional transcriptome signature with max area under ROC curve (AUC) (0.69 in the training group and 0.62 in the test group). The selected signature composed by VAT1L, CALR, LINC01456, RP11-484L8.1, MIR196A1 and MIR148A, separated the training group patients into high-risk or low-risk subgroup with significantly different survival time (median survival: 35.3 months vs. 64.9 months, P < 0.001). The signature was validated in the test group showing similar prognostic values (median survival: 41.6 months in high-risk vs. 57.4 months in low-risk group, P=0.018). Chi-square test and multivariable Cox regression analysis showed that the signature was an independent prognostic factor for patients with ovarian serous carcinoma. Finally, we validated the expression of the genes experimentally.

A long non-coding RNA expression signature to predict survival of patients with colon adenocarcinoma

Colon cancer is the most common type of gastrointestinal cancer and is still the leading cause of cancer-related mortality worldwide. Long non-coding RNAs (lncRNAs) have been proved to be superior biomarkers in cancer diagnosis and prognosis than miRNAs and protein-coding genes. In the current study, our objective was to detect novel lncRNA biomarkers by analyzing lncRNA expression profiles and clinical data in a large cohort of patients with colon patients from The Cancer Genome Atlas (TCGA). By using Cox regression analysis, we identified two lncRNAs (SNHG6 and CTD-2354A18.1) which could be independent prognostic factors for predicting clinical outcome in colon adenocarcinoma. Then a linear combination of these two lncRNA biomarkers (SNHG6 and CTD-2354A18.1), termed two-lncRNA signature, was developed in the training set as a predictor for OS in patients with colon adenocarcinoma, and validated in the testing set and the entire patient set. This two-lncRNA signature demonstrated significant prognostic performance in both the testing set and the entire patient set which classified the patients into two groups with significantly different OS. The multivariate and stratified analysis suggested that the prognostic value of the two-lncRNA signature was independent of other traditional clinical variables. Functional analysis suggested that these two lncRNA biomarkers might be mainly involved in transcription/translation-related or DNA repair-related biological processes. In summary, our results warrant further studies on these lncRNAs that will improve our understanding of the mechanisms associated with pathogenesis and progression of colon adenocarcinoma.

LEF1-AS1, a long-noncoding RNA, promotes malignancy in glioblastoma

OBJECTIVES

The long-noncoding RNAs (lncRNAs) are identified as new crucial regulators of diverse cellular processes in glioblastoma (GBM) tissues. However, the expression pattern and biological function of lncRNAs remain largely unknown. Here, for the first time, the effects of lncRNA lymphoid enhancer-binding factor 1 antisense RNA 1 (LEF1-AS1) on GBM progression both in vitro and in vivo are investigated.

MATERIALS AND METHODS

Expression profiles of LEF1-AS1 in GBM specimens were investigated by bioinformatics analyses. LEF1-AS1 expression in GBM tissues was detected using a quantitative polymerase chain reaction. LEF1-AS1 expression was inhibited by transfecting the LEF1-AS1-specific small interfering RNAs (siRNAs) and stable cell lines established were inhibited by transfecting si-LEF1-AS1 viruses. The Cell Counting Kit-8, ethynyl deoxyuridine, and colony formation assay were used to examine proliferation function. The flow cytometry detected cell-cycle change and apoptosis. Migration effects were detected by a Transwell assay. The tumor xenografts and immunohistochemistry were performed to evaluate tumor growth in vivo.

RESULTS

In this study, LEF1-AS1 expression was found significantly upregulated in GBM specimens compared with normal tissues. The 5-year overall survival in GBM patients from The Cancer Genome Atlas with high expression of LEF1-AS1 was inferior to that with low expression. It was confirmed that expression of LEF1-AS1 was higher in GBM tissues than normal ones. Knockdown of LEF1-AS1 significantly inhibited the malignancy of GBM cells, including proliferation and invasion, and promoted cell apoptosis. The result of Western blot assays indicated that knockdown of LEF1-AS1-mediated tumor suppression in GBM cells may be via the reduction of ERK and Akt/mTOR signaling activities. Finally, the in vivo experiment also demonstrated that knockdown LEF1-AS1 inhibited the growth-promoting effect of LEF1-AS1 of U87 cells.

CONCLUSION

Our result indicated that lncRNA LEF1-AS1 acts as an oncogene in GBM and may be a pivotal target for this disease.

The lncRNA HOXA11-AS functions as a competing endogenous RNA to regulate PADI2 expression by sponging miR-125a-5p in liver metastasis of colorectal cancer

Several long non-coding RNAs (lncRNAs) play important roles in the regulation of liver metastasis in colorectal cancer (CRC) patients. We previously described the potential involvement of HOMEOBOX A11 (HOXA11) antisense RNA (HOXA11-AS), miR-125a-5p, and peptidyl arginine deiminase 2 (PADI2) in promoting liver metastasis in CRC patients. In the present study, we verified the significant upregulation of HOXA11-AS and PADI2, as well as the downregulation of miR-125a-5p, in CRC patients with liver metastasis. Overexpression and knockdown studies of HOXA11-AS or PADI2, as well as gain-/loss-of-function studies of miR-125a-5p, revealed a positive correlation between HOXA11-AS and PADI2 and a negative correlation with miR-125a-5p in the regulation of liver metastasis in CRC cell lines. Overall, we conclude that HOXA11-AS promotes liver metastasis in CRC by functioning as a miR-125a-5p sponge and describe a novel HOXA11-AS–miR-125a-5p–PADI2 regulatory network involved in CRC liver metastasis.

Genetic polymorphisms of long non-coding RNA GAS5 predict platinum-based concurrent chemoradiotherapy response in nasopharyngeal carcinoma patients

LncRNA GAS5 plays a tumor suppressive role in a variety of human cancers and promises to be a novel diagnostic biomarker, therapy target, as well as prognostic biomarker. However, the role of GAS5 in nasopharyngeal carcinoma (NPC) remains elusive. The objective of the present study was to evaluate the effect of single nucleotide polymorphisms (SNPs) in GAS5 on treatment efficacy and toxicity in NPC patients receiving chemoradiotherapy. Three potentially functional SNPs of GAS5 were genotyped in 267 NPC patients and validated in another 238 NPC patients treated with chemoradiotherapy from southern China. Multivariate logistic regression analyses and stratification analyses were used to estimate the association of candidate SNPs and chemoradiotherapy efficacy and toxic reactions. Our results showed that rs2067079 kept a consistent association with severe myelosuppression and severe neutropenia in discovery set (OR=2.403, P=0.009; OR=2.454, P=0.015; respectively), validation set (OR=3.653, P=0.027; OR=4.767, P=0.016; respectively), and combined dataset (OR=1.880, P=0.007; OR=2.079, P=0.005; respectively). rs2067079 CT genotype carriers presented an even more remarkable increased risk of severe myelosuppression (OR=3.878, P=0.003) and severe neutropenia (OR=3.794, P=0.009) in subgroups taking paclitaxel+platinum as concurrent chemoradiotherapy regimen. Besides, we found a gene-does effect of rs6790, with the incidence rate of severe myelosuppression decreased from 23.56% to 17.21% to 10% and the incidence rate of severe neutropenia decreased from 30.4% to 20.9% to 17.1% for rs6790 GG vs GA vs AA genotype carriers. Our results indicate the potential role of lncRNA GAS5 polymorphisms rs2067079 and rs6790 as predictive biomarkers for chemoradiotherapy induced toxic reactions in NPC patients.

H19 promotes the migration and invasion of colon cancer by sponging miR-138 to upregulate the expression of HMGA1

Colon cancer is the most common digestive system malignancy, along with high mortality rate, familial transmissibility and hepatic metastasis. Our study investigated the role of long non-coding RNA H19 in colon cancer. We found that H19 was overexpressed in colon cancer tissues and cell lines, the interference of H19 by short hairpin RNA (shRNA) effectively decreased the migration and invasion of colon cancer cells (HT-29 and RKO). Besides, miR-138 was predicted a target of H19, and low expression of miR-138 was found in colon cancer tissues and cells. The silence of H19 strongly increased the expression of miR-138. The decreased level of miR-138 was elevated adding miR-138 mimic in RKO cells transfected with lncRNA-H19. Similarly, the upregulated level of miR-138 was downregulated adding miR-138 inhibitor in RKO cells transfected with H19 shRNA. The luciferase reporter confirmed the targeting reaction between H19 and miR-138. Moreover, the high-mobility group A (HMGA1) protein was predicted as a target of miR-138. HMGA1 was suppressed by H19 shRNA and could be up-regulated by miR-138 inhibitor. The migration and invasion ability of colon cancer was restrained by H19 shRNA and promoted by miR-138 inhibitor. Finally, the in vivo experiment revealed that H19 shRNA strongly reduced the tumor growth and tumor volume. H19 shRNA also inhibited metastasis via suppressing hepatic metastases and the expression of metastasis-related proteins. Taken together, our research indicated an H19-miR138-HMGA1 pathway in regulating the migration and invasion of colon cancer, providing new insight for treatment of colon cancer.