Long non-coding RNA CCAT1 promotes gallbladder cancer development via negative modulation of miRNA-218-5p

HOTAIR, a long non-coding RNA driver of malignancy whose expression is activated by FOXC1, negatively regulates miRNA-1 in hepatocellular carcinoma

Evidence is rapidly accumulating that long non-coding RNAs (lncRNAs) are involved in human tumorigenesis and are dysregulated in multiple cancers, including hepatocellular carcinoma (HCC). lncRNAs can regulate essential pathways that contribute to tumor initiation and progression with tissue specificity, which suggests that lncRNAs may be valuable biomarkers and therapeutic targets. HOX transcript antisense intergenic RNA (HOTAIR) has previously been demonstrated to be an oncogene and a negative prognostic factor in a variety of cancers; however, the factors that contribute to the upregulation of HOTAIR and the interaction between HOTAIR and microRNAs (miRNAs or miRs) are largely unknown. In the present study, the expression levels of HOTAIR, forkhead box C1 (FOXC1) and miRNA-1 were examined in 50 matched pairs of HCC and HCC cells. The effects of HOTAIR on HCC cell proliferation were tested using trypan blue exclusion assay. The effect of HOTAIR on HCC growth in vivo was determined in a (nu/nu) mouse model. A computational screening of HOTAIR promoter was conducted to search for transcription factor-binding sites. FOXC1 binding to the promoter region of HOTAIR was confirmed using a chromatin immunoprecipitation assay. A search for miRNAs that had complementary base paring with HOTAIR was performed utilizing an online software program. The interaction between miR-1 and HOTAIR was examined using a luciferase reporter assay. Gain and loss of function approaches were used to determine the changes of HOTAIR or miR-1 expression. The relative levels of FOXC1 and HOTAIR expression in HCC tissues and HepG2 cells were significantly higher than those in normal liver LO2 cells and adjacent carcinoma tissues; the relative expression of miR-1 exhibited the opposite pattern. Overexpression of HOTAIR promoted HCC cell proliferation and progression of tumor xenografts. The present authors have demonstrated that FOXC1 binds to the upstream region of HOTAIR in HCC cells and that FOXC1 activates lncRNA HOTAIR expression in HCC HepG2 cells, which suggests that HOTAIR harbors a miRNA-1 binding site. The present data revealed that this binding site is vital for the regulation of miRNA-1 by HOTAIR. Furthermore, HOTAIR negatively regulated the expression of miRNA-1 in HepG2 cells. Additionally, the present study demonstrated that the oncogenic activity of HOTAIR is in part based on the negative regulation of miR-1. Taken together, these results suggest that HOTAIR is a FOXC1-activated driver of malignancy, which acts in part through the repression of miR-1.

Current Status of Long Non-Coding RNAs in Human Breast Cancer

Breast cancer represents a major health burden in Europe and North America, as recently published data report breast cancer as the second leading cause of cancer related death in women worldwide. Breast cancer is regarded as a highly heterogeneous disease in terms of clinical course and biological behavior and can be divided into several molecular subtypes, with different prognosis and treatment responses. The discovery of numerous non-coding RNAs has dramatically changed our understanding of cell biology, especially the pathophysiology of cancer. Long non-coding RNAs (lncRNAs) are non-protein-coding transcripts >200 nucleotides in length. Several studies have demonstrated their role as key regulators of gene expression, cell biology and carcinogenesis. Deregulated expression levels of lncRNAs have been observed in various types of cancers including breast cancer. lncRNAs are involved in cancer initiation, progression, and metastases. In this review, we summarize the recent literature to highlight the current status of this class of long non-coding lncRNAs in breast cancer.

The long non-coding RNA, SNHG6-003, functions as a competing endogenous RNA to promote the progression of hepatocellular carcinoma

The expression of long non-coding RNAs (lncRNAs) is dysregulated in hepatocellular carcinoma (HCC). However, the functions and contributions of lncRNAs remain largely unknown. Here, we identified a critical role of SNHG6-003 in HCC. We found that five SNHG6 transcripts were differentially expressed in HCC tissues while only the SNHG6-003 had an oncogenic function. Ectopic expression of SNHG6-003 in HCC cells promoted cell proliferation and induced drug resistance, whereas SNHG6-003 knockdown promoted apoptosis. Moreover, SNHG6-003 functioned as a competitive endogenous RNA (ceRNA), effectively becoming sponge for miR-26a/b and thereby modulating the expression of transforming growth factor-β-activated kinase 1 (TAK1). Importantly, expression analysis revealed that both SNHG6-003 and TAK1 were upregulated in human cancers, exhibiting a co-expression pattern. In HCC patients, high expression of SNHG6-003 closely correlated with tumor progression and shorter survival. Thus, targeting the ceRNA network involving SNHG6-003 may be used as a treatment strategy against HCC.

Long non-coding RNA NEAT1 promotes non-small cell lung cancer progression through regulation of miR-377-3p-E2F3 pathway

Recently, the long non-coding RNA (lncRNA) NEAT1 has been identified as an oncogenic gene in multiple cancer types and elevated expression of NEAT1 was tightly linked to tumorigenesis and cancer progression. However, the molecular basis for this observation has not been characterized in progression of non-small cell lung cancer (NSCLC). In our studies, we identified NEAT1 was highly expressed in patients with NSCLC and was a novel regulator of NSCLC progression. Patients whose tumors had high NEAT1 expression had a shorter overall survival than patients whose tumors had low NEAT1 expression. Further, NEAT1 significantly accelerates NSCLC cell growth and metastasis in vitro and tumor growth in vivo. Additionally, by using bioinformatics study and RNA pull down combined with luciferase reporter assays, we demonstrated that NEAT1 functioned as a competing endogenous RNA (ceRNA) for hsa-miR-377-3p, antagonized its functions and led to the de-repression of its endogenous targets E2F3, which was a core oncogene in promoting NSCLC progression. Taken together, these observations imply that the NEAT1 modulated the expression of E2F3 gene by acting as a ceRNA, which may build up the missing link between the regulatory miRNA network and NSCLC progression.

Epigenetic silencing of miR-218 by the lncRNA CCAT1, acting via BMI1, promotes an altered cell cycle transition in the malignant transformation of HBE cells induced by cigarette smoke extract

Cigarette smoking is the strongest risk factor for the development of lung cancer, the leading cause of cancer-related deaths. However, the molecular mechanisms leading to lung cancer are largely unknown. A long-noncoding RNA (lncRNA), CCAT1, regarded as cancer-associated, has been investigated extensively. Moreover, the molecular mechanisms of lncRNAs in regulation of microRNAs (miRNAs) induced by cigarette smoke remain unclear. In the present investigation, cigarette smoke extract (CSE) caused an altered cell cycle and increased CCAT1 levels and decreased miR-218 levels in human bronchial epithelial (HBE) cells. Depletion of CCAT1 attenuated the CSE-induced decreases of miR-218 levels, suggesting that miR-218 is negatively regulated by CCAT1 in HBE cells exposed to CSE. The CSE-induced increases of BMI1 levels and blocked by CCAT1 siRNA were attenuated by an miR-218 inhibitor. Moreover, in CSE-transformed HBE cells, the CSE-induced cell cycle changes and elevated neoplastic capacity were reversed by CCAT1 siRNA or BMI1 siRNA. This epigenetic silencing of miR-218 by CCAT1 induces an altered cell cycle transition through BMI1 and provides a new mechanism for CSE-induced lung carcinogenesis.

Transcriptome profiling of lncRNA and co-expression networks in esophageal squamous cell carcinoma by RNA sequencing

Long non-coding RNAs (lncRNAs) are emerging as crucial regulators of cancer. To identify novel targets for further study in esophageal squamous cell carcinoma (ESCC), we performed a genome-wide analysis of lncRNA expression in 12 ESCC tumor and normal tissues. Publicly available RNA-seq data were downloaded from the NCBI, GEO, and Co-LncRNA databases, and lncRNA and messenger RNA (mRNA) expression profiles were analyzed. In total, 127 lncRNAs were found to be differentially expressed, with a greater than fourfold change in ESCC tumor tissues compared with normal tissues. Among these lncRNAs, 98 were upregulated and 29 downregulated. Moreover, 1469 network nodes and 1720 connection edges between 119 lncRNAs and 1350 coding genes were integrated into the lncRNA and mRNA co-expression network. Bioinformatic analysis using GO terms revealed that these dysregulated lncRNAs are associated with developmental processes, proteinaceous extracellular matrix, and protein binding activity, with ECM-receptor interaction and the PI3K-Akt signaling pathway enrichment. Lastly, qRT-PCR results verified two significantly upregulated lncRNAs and three significantly downregulated lncRNAs in 50 pairs of ESCC tissues and adjacent normal tissues. These results reveal the landscape of ESCC-associated lncRNAs and co-expression networks, providing important insight regarding the lncRNAs involved in ESCC.

Overexpression of LncRNA-ROR predicts a poor outcome in gallbladder cancer patients and promotes the tumor cells proliferation, migration, and invasion

LncRNA-ROR has been reported to be involved in many kinds of human cancers. However, whether LncRNA-ROR is involved in gallbladder cancer progression remains largely unknown. The objective of this study is to investigate the role of LncRNA-ROR in gallbladder cancer. We found that LncRNA-ROR expression level was upregulated in gallbladder cancer tissues (P < 0.05) and was significantly associated with tumor sizes (P < 0.05) and lymph node metastasis (P < 0.05). High expression of LncRNA-ROR was significantly associated with poor prognosis in gallbladder cancer patients (P < 0.05). Moreover, knockdown of LncRNA-ROR inhibited cell proliferation, migration, and invasion. The epithelial-mesenchymal transition (EMT) phenotype induced by TGF-β1 was reversed after LncRNA-ROR knocking down in SGC-996 and Noz cells. LncRNA-ROR plays an important role in the development of gallbladder cancer and mediates the EMT in gallbladder cancer. LncRNA-ROR might act as a marker of prognosis and therapeutic target for gallbladder cancer.

Long noncoding RNAs in digestive system cancers: Functional roles, molecular mechanisms, and clinical implications (Review)

Long noncoding RNAs (lncRNAs) are emerging as new players in various diseases including cancer. LncRNAs have been shown to play multifaceted roles in the development, progression, and metastasis of cancer. In this review, we highlight the lncRNAs that are critically involved in the pathogenesis of digestive system cancers (DSCs). We summarize the roles of the lncRNAs in DSCs and the underlying mechanisms responsible for their functions. The DSC-associated lncRNAs interact with a wide spectrum of molecules to regulate gene expression at transcriptional, post-transcriptional, and translational levels. We also provide new insights into the clinical significance of these lncRNAs, which are found to be closely associated with the aggressiveness of DSCs and could predict the prognosis of DSC patients. Moreover, lncRNAs have been suggested as promising therapeutic targets in DSCs. Therefore, better understanding of the functional roles of lncRNAs will provide new biomarkers for DSC diagnosis, prognosis, and therapy.

Long non-coding RNA MINCR promotes gallbladder cancer progression through stimulating EZH2 expression

The regulation of MYC-regulated long non-coding RNAs has been reported to contribute to certain types of cancers. However, the role of MYC-induced long non-coding RNA (MINCR) in the tumorigenesis of gallbladder cancer (GBC) is still largely unknown. In this study, we discovered that MINCR was markedly upregulated in GBC tissues compared with adjacent normal tissues. High MINCR expression levels in GBC were positively associated with tumor volume and lymph node metastasis and were negatively correlated with overall survival (OS). Upregulation of MINCR and enhancer of zeste homolog 2 (EZH2) in GBC coincided with the downregulation of miR-26a-5p in GBC. Mechanistically, MINCR/miR-26a-5p/EZH2 axis was found to be involved in cell proliferation, cell invasive and apoptosis in GBC cells. Moreover, knockdown of MINCR suppressed cell proliferation, decreased S-phase cell numbers, increased cell apoptosis, and inhibited cell invasion by inhibiting the epithelial-mesenchymal transition (EMT) phenomenon in GBC cells. In vivo, tumor volumes were significantly decreased in the MINCR silencing group compared with those in the control group. These results demonstrated that MINCR could potentially be a therapeutic target as well as a prognostic marker in GBC.

Circulating MicroRNAs as Biomarkers in Biliary Tract Cancers

Biliary tract cancers (BTCs) are a group of highly aggressive malignant tumors with a poor prognosis. The current diagnosis is based mainly on imaging and intraoperative exploration due to brush cytology havinga low sensitivity and the standard markers, such as carcinoembryonic antigen (CEA) and carbohydrate 19-9 (CA19-9), not having enough sensitivity nor specificity to be used in a differential diagnosis and early stage detection. Thus, better non-invasive methods that can distinguish between normal and pathological tissue are needed. MicroRNAs (miRNAs) are small, single-stranded non-coding RNA molecules of ~20–22 nucleotides that regulate relevant physiological mechanisms and can also be involved in carcinogenesis. Recent studies have demonstrated that miRNAs are detectable in multiple body fluids, showing great stability, either free or trapped in circulating microvesicles, such as exosomes. miRNAs are ideal biomarkers that may be used in screening and prognosis in biliary tract cancers, aiding also in the clinical decisions at different stages of cancer treatment. This review highlights the progress in the analysis of circulating miRNAs in serum, plasma and bile as potential diagnostic and prognostic markers of BTCs.

The long noncoding RNA CASC2 functions as a competing endogenous RNA by sponging miR-18a in colorectal cancer

Recent evidence highlights the crucial regulatory roles of long noncoding RNAs (lncRNA) in tumor biology. In colorectal cancer (CRC), the expression of several lncRNAs is dysregulated and play essential roles in CRC tumorigenesis. However, the potential biological roles and regulatory mechanisms of the novel human lncRNA, CASC2 (cancer susceptibility candidate 2), in tumor biology are poorly understood. In this study, CASC2 expression was significantly decreased in CRC tissues and CRC cell lines, and decreased expression was significantly more frequent in patients with advanced tumor-node-metastasis stage disease (TNM III and IV) (P = 0.028). Further functional experiments indicate that CASC2 could directly upregulate PIAS3 expression by functioning as a competing endogenous RNA (ceRNA) for miR-18a. This interactions leads to the de-repression of genes downstream of STAT3 and consequentially inhibition of CRC cell proliferation and tumor growth in vitro and in vivo by extending the G₀/G₁-S phase transition. Taken together, these observations suggest CASC2 as a ceRNA plays an important role in CRC pathogenesis and may serve as a potential target for cancer diagnosis and treatment.

The role of microRNAs in gallbladder cancer

MicroRNAs (also referred to as miRNAs or miRs) play a crucial role in post-transcriptional gene regulation and serve as negative gene regulators by controlling a variety of target genes and regulating diverse biological processes, such as cell proliferation, invasion, migration and apoptosis. Aberrant expression of miRNAs is associated with the development and progression of cancer. Recent studies have reported that miRNAs may repress or promote the expression of cancer-related genes via several different signaling pathways in gallbladder cancer (GBC) patients and may function as tumor suppressors or oncogenes, thus providing a promising tool for the diagnosis and therapeutics of GBCs. In this review, we summarize the role of dysregulawted miRNA expression in the signaling pathways implicated in GBC and discuss the significant role of circulating miRNAs in GBC. Therefore, miRNAs may serve as novel therapeutic targets as well as diagnostic or prognostic markers in GBC.

Long non-coding RNA ADNCR suppresses adipogenic differentiation by targeting miR-204

Adipogenesis is a complex and precisely orchestrated process mediated by a network of adipogenic regulatory factors. Several studies have highlighted the relevance of lncRNAs in adipocyte differentiation, but the precise molecular mechanism has largely remained elusive. In the present study, we performed Ribo-Zero RNA-Seq to investigate both the poly(A)+and poly(A)-lncRNAs of in vitro cultured bovine preadipocytes and differentiated adipocytes. A stringent set of 2882 lncRNAs was finally identified. A comparison of the lncRNAs expression profiles revealed that 16 lncRNAs are differentially expressed during adipocyte differentiation. We focused on the most downregulated lncRNA, which we named adipocyte differentiation-associated long noncoding RNA (ADNCR). Mechanistically, ADNCR inhibited adipocyte differentiation by functioning as a competing endogenous RNA (ceRNA) for miR-204, thereby augmenting the expression of the miR-204 target gene, SIRT1, which is known to inhibit adipocyte differentiation and adipogenic gene expression by docking with NCoR and SMART to repress PPARγ activity. Our data not only provide a valuable genomic resource for the identification of lncRNAs with functional roles in adipocyte differentiation but also reveal new insights into understanding the mechanisms of adipogenic differentiation.

BMI1: A Biomarker of Hematologic Malignancies

BMI1 oncogene is a catalytic member of epigenetic repressor polycomb group proteins. It plays a critical role in the regulation of gene expression pattern and consequently several cellular processes during development, including cell cycle progression, senescence, aging, apoptosis, angiogenesis, and importantly self-renewal of adult stem cells of several lineages. Preponderance of evidences indicates that deregulated expression of PcG protein BMI1 is associated with several human malignancies, cancer stem cell maintenance, and propagation. Importantly, overexpression of BMI1 correlates with therapy failure in cancer patients and tumor relapse. This review discusses the diverse mode of BMI1 regulation at transcriptional, posttranscriptional, and posttranslational levels as well as at various critical signaling pathways regulated by BMI1 activity. Furthermore, this review highlights the role of BMI1 as a biomarker and therapeutic target for several subtypes of hematologic malignancies and the importance to target this biomarker for therapeutic applications.

CCAT1: a pivotal oncogenic long non-coding RNA in human cancers

Long non-coding RNAs (lncRNAs) compose a group of non-protein-coding RNAs - more than 200 nucleotides in length. Recent studies have shown that lncRNAs play important roles in different cellular processes, including proliferation, differentiation, migration and invasion. Deregulation of lncRNAs has been widely reported in human tumours, in which they are able to function as either oncogenes (on the one hand) or tumour suppressor genes (on the other). Deregulation of CCAT1 (colon cancer-associated transcript-1), an oncogenic lncRNA, has been documented in different types of malignancy, such as gastric cancer, colorectal cancer and hepatocellular carcinoma. In this regard, enforced expression of CCAT1 exerts potent tumorigenic effects by promoting cell proliferation, invasion and migration. Recent evidence has also shown that CCAT1 may serve as a prognostic cancer biomarker. In this review, we provide an overview of current evidence relating to the role and biological function of CCAT1 in tumour development.

Non-coding RNAs as emerging molecular targets of gallbladder cancer

Gallbladder cancer is one of the most common cancers of biliary tract with aggressive pathophysiology, now emerging as a global health issue. Although minority of gallbladder cancer patients could receive such curative resection due to late diagnosis, this increases the survival rate. Lack of potential target molecule (s) for early diagnosis, better prognosis and effective therapy of gallbladder cancer has triggered investigators to look for novel technological or high throughput approaches to identify potential biomarker for gallbladder cancer. Intervention of non-coding RNAs in gallbladder cancer has been revealed recently. Non-coding RNAs are now widely implicated in cancer. Recent reports have revealed association of non-coding RNAs (microRNAs or miRNAs and long non-coding RNAs or lncRNAs) with gallbladder cancer. Here, we present an updated overview on the biogenesis, mechanism of action, role of non-coding RNAs, the identified cellular functions in gallbladder tumorigenesis, their prognostic & therapeutic potentials (efficacies) and future significance in developing effective biomarker(s), in future, for gallbladder.

MicroRNA-92b promotes hepatocellular carcinoma progression by targeting Smad7 and is mediated by long non-coding RNA XIST

MicroRNA (miRNA) and long non-coding RNA (lncRNA) have been demonstrated to participate in the progression of many cancers. Hepatocellular carcinoma (HCC) is one of the most common and aggressive malignant tumors worldwide, while the molecular mechanisms underlying HCC tumorigenesis are not completely clear. In this study, we showed that miR-92b was significantly upregulated in tumor tissue and plasma of HCC patients, and its expression level was highly correlated with gender and microvascular invasion. Functionally, miR-92b could promote cell proliferation and metastasis of HCC in vitro and in vivo. Mechanistic investigations suggested that Smad7, which exhibited an inverse relationship with miR-92b expression in HCC, was a direct target of miR-92b and could reverse its effects on HCC tumorigenesis. Furthermore, long non-coding RNA (lncRNA) X-inactive specific transcript (XIST) and miR-92b could directly interact with and repress each other, and XIST could inhibit HCC cell proliferation and metastasis by targeting miR-92b. Taken together, our study not only revealed for the first time the importance of XIST/miR-92b/Smad7 signaling axis in HCC progression but also suggested the potential value of miR-92b as a biomarker in the clinical diagnosis and treatment of HCC.

A novel cell cycle-associated lncRNA, HOXA11-AS, is transcribed from the 5-prime end of the HOXA transcript and is a biomarker of progression in glioma

The comprehensive lncRNA expression signature in glioma has not yet been fully elucidated. We performed a high-throughput microarray to detect the ncRNA expression profiles of 220 human glioma tissues. Here, we found that a novel lncRNA, HOXA11-AS, was the antisense transcript of the HOX11 gene. It was shown that HOXA11-AS was closely associated with glioma grade and poor prognosis. Multivariate Cox regression analysis revealed that HOXA11-AS was an independent prognostic factor in glioblastoma multiforme patients, and its expression was correlated with the glioma molecular subtypes of the Cancer Genome Atlas. Gene set enrichment analysis indicated that the gene sets most correlated with HOXA11-AS expression were involved in cell cycle progression. Over-expression of the HOXA11-AS transcript promoted cell proliferation in vitro, while knockdown of HOXA11-AS expression repressed cell proliferation via regulation of cell cycle progression. The growth-promoting and growth-inhibiting effects of HOXA11-AS were also demonstrated in a xenograft mouse model. Our data confirms, for the first time, that HOXA11-AS is an important long non-coding RNA that primarily serves as a prognostic factor for glioma patient survival. HOXA11-AS could serve as a biomarker for identifying glioma molecular subtypes and as therapeutic target for glioma patients.

The Emerging Function and Mechanism of ceRNAs in Cancer

Complex diseases, such as cancer, are often associated with aberrant gene expression at both the transcriptional and post-transcriptional level. Over the past several years, competing endogenous RNAs (ceRNAs) have emerged as an important class of post-transcriptional regulators that alter gene expression through a miRNA-mediated mechanism. Recent studies in both solid tumors and hematopoietic malignancies showed that ceRNAs have significant roles in cancer pathogenesis by altering the expression of key tumorigenic or tumor-suppressive genes. Characterizing the identity, function, and mechanism of the ceRNAs will not only further our fundamental understanding of RNA-mediated cancer pathogenesis, but may also shed light on the development of new RNA-based therapeutic strategies for treating cancer.

3-Econsystems: MicroRNAs, Receptors, and Latent Viruses; Some Insights Biology Can Gain from Economic Theory

This mini-review describes three biological systems. All three include competing molecules and a limiting molecule that binds the competing molecules. Such systems are extensively researched by economists. In fact, the issue of limited resources is the defining feature of economic systems. Therefore, we call these systems "econsystems." In an econsystem, the allocation of the limiting molecule between the competing molecules determines the behavior of the system. A cell is an example of an econsystem. Therefore, a change in the allocation of a limiting molecule as a result of, for instance, an abnormal change in the concentration of one of the competing molecules, may result in abnormal cellular behavior, and disease. The first econsystem described in this mini-review includes a long non-coding RNA and a messenger RNA (lncRNA and mRNA). The limiting molecule is a microRNA (miRNA). The lncRNA and mRNA are known as competing endogenous RNAs (ceRNAs). The second econsystem includes two receptors, and the limiting molecule is a ligand. The third econsystem includes a cis-regulatory element of a latent virus and that of a human gene. The limiting molecule is a transcription complex that binds both cis-elements.

Long non-coding RNAs as novel targets for therapy in hepatocellular carcinoma

The recognition of functional roles for transcribed long non-coding RNA (lncRNA) has provided a new dimension to our understanding of cellular physiology and disease pathogenesis. LncRNAs are a large group of structurally complex RNA genes that can interact with DNA, RNA, or protein molecules to modulate gene expression and to exert cellular effects through diverse mechanisms. The emerging knowledge regarding their functional roles and their aberrant expression in disease states emphasizes the potential for lncRNA to serve as targets for therapeutic intervention. In this concise review, we outline the mechanisms of action of lncRNAs, their functional cellular roles, and their involvement in disease. Using liver cancer as an example, we provide an overview of the emerging opportunities and potential approaches to target lncRNA-dependent mechanisms for therapeutic purposes.

LncRNA-ATB mediated E-cadherin repression promotes the progression of colon cancer and predicts poor prognosis

BACKGROUND

Long non-coding RNA-activated by TGF-β (lncRNA-ATB) promotes the invasion-metastasis cascade in hepatocellular carcinoma via downregulating E-cadherin (E-cad) and inducing epithelial-to- mesenchymal transition (EMT) and is clinically significant in human colon cancer. However, its molecular mechanisms in colon cancer progression remain unclear. This study aimed to elucidate the role of lncRNA-ATB and its clinical value in colon cancer.

METHODS

Expression levels of lncRNA-ATB in colon cancer tissues and colon cancer cell lines were evaluated using quantitative real-time polymerase chain reaction. The clinicopathological significance and prognostic value of lncRNA-ATB were investigated, and roles of lncRNA-ATB in regulating E-cad and other EMT-related markers expression and colon cancer progression were evaluated in vitro. Expression levels of lncRNA-ATB and E-cad in human plasma were evaluated.

RESULTS

Long non-coding RNA-activated by TGF-β was upregulated in colon cancer tissues compared with adjacent mucosa (P < 0.001). LncRNA-ATB levels were also higher in metastatic cancer tissues (P < 0.001). Among the three highly invasive colon cancer cell lines, lncRNA-ATB levels were relatively higher with concurrent low levels of E-cad compared with levels in the three low-invasive cell lines. LncRNA-ATB expression correlated with pN stage (P < 0.01) and American Joint Committee on Cancer stage (P < 0.01). Striking differences were observed in overall survival and disease-free survival in cases with both high lncRNA-ATB expression and low E-cad expression. Reduction of lncRNA-ATB increased expression of epithelial markers E-cad, ZO-1, and decreased expression of mesenchymal markers ZEB1 and N-cadherin (N-cad), and significantly influenced colon cancer cell progression. Plasma lncRNA-ATB was upregulated in colon cancer patients one month after surgery (P < 0.05).

CONCLUSIONS

Long non-coding RNA-activated by TGF-β may act on colon tumorigenesis by suppressing E-cad expression and promoting EMT process, and lncRNA-ATB inhibition may provide a promising therapeutic option for suppressing colon cancer progression.

Long Noncoding RNA PVT1 Promotes Non-Small Cell Lung Cancer Cell Proliferation through Epigenetically Regulating LATS2 Expression

Long noncoding RNAs (lncRNA) are a novel class of transcripts with no protein coding capacity, but with diverse functions in cancer cell proliferation, apoptosis, and metastasis. The lncRNA PVT1 is 1,716 nt in length and located in the chr8q24.21 region, which also contains the myelocytomatosis (MYC) oncogene. Previous studies demonstrated that MYC promotes PVT1 expression in primary human cancers. However, the expression pattern and potential biologic function of PVT1 in non-small cell lung cancer (NSCLC) is still unclear. Here, we found that PVT1 was upregulated in 105 human NSCLC tissues compared with normal samples. High expression of PVT1 was associated with a higher tumor-node-metastasis stage and tumor size, as well as poorer overall survival. Functional analysis revealed that knockdown of PVT1 inhibited NSCLC cell proliferation and induced apoptosis both in vitro and in vivo RNA immunoprecipitation and chromatin immunoprecipitation assays demonstrated that PVT1 recruits EZH2 to the large tumor suppressor kinase 2 (LATS2) promoter and represses LATS2 transcription. Furthermore, ectopic expression of LATS2 increased apoptosis and repressed lung adenocarcinoma cell proliferation by regulating the Mdm2-p53 pathway. Taken together, our findings indicated that PVT1/EZH2/LATS2 interactions might serve as new target for lung adenocarcinoma diagnosis and therapy. Mol Cancer Ther; 15(5); 1082-94. ©2016 AACR.

Long noncoding RNA ENST00000434223 suppressed tumor progression in non-small cell lung cancer

In spite of the fact that the great progress has been made in the treatment of non-small cell lung cancer (NSCLC), the prognosis of NSCLC remains comparatively dismal. Therefore, it is of great value to identify novel effective diagnostic biomarkers and therapeutic targets of NSCLC. Emerging evidence has demonstrated the vital roles of long noncoding RNAs (lncRNAs) in cancer development. ENST00000434223 was recently identified as a lncRNA that is downregulated in early stage lung adenocarcinoma in a profiling study. However, little is known about its role in the development of NSCLC. In the present study, we found that ENST00000434223 was greatly downregulated in cancer tissues compared to adjacent normal tissues. ENST00000434223 overexpression suppressed the proliferation and migration in NSCLC cell lines in vitro. Moreover, ENST00000434223 overexpression reversed the epithelial-mesenchymal transition in NSCLC cell line. Our study suggests that ENST00000434223 may be a potential biomarker and a therapeutic target of NSCLC.

Downregulation of long non-coding RNA TRIM52-AS1 functions as a tumor suppressor in renal cell carcinoma

Long non-coding RNAs (lncRNAs) are important regulators of gene expression, interacting with the major pathways of cell growth, proliferation, differentiation and survival. Alterations in the function of lncRNAs promote tumor formation, progression and metastasis. The purpose of the present study was to identify novel tumor suppressor lncRNAs, and elucidate their physiological function and mechanism in renal cell carcinoma (RCC). The results of the present study revealed that the expression of the lncRNA, TRIM52‑AS1, was downregulated in RCC, which was demonstrated using reverse transcription‑quantitative polymerase chain reaction analysis. Furthermore, the effects of TRIM52‑AS1 on proliferation, cell migration and apoptosis were analyzed using a wound scratch assay, a 3‑(4,5‑dimethylthiazol‑2yl)‑2,5‑diphenyl tetrazolium bromide assay and flow cytometric analysis, respectively. The overexpression of TRIM52‑AS1 using a synthesized vector significantly suppressed cell migration and proliferation, and induced apoptosis of the RCC cells in vitro, and interference of its expression led to the opposite effects. The present study was the first, to the best of our knowledge, to demonstrate that TRIM52‑AS1 functions as a tumor suppressor in RCC. Further investigation is required to elucidate the molecular mechanisms underlying the effects of TRIM52-AS1 in the development of RCC.

MicroRNA aberrations: An emerging field for gallbladder cancer management

Gallbladder cancer (GBC) is infrequent but most lethal biliary tract malignancy characterized by an advanced stage diagnosis and poor survival rates attributed to absence of specific symptoms and effective treatment options. These necessitate development of early prognostic/predictive markers and novel therapeutic interventions. MicroRNAs (miRNAs) are small, non-coding RNA molecules that play a key role in tumor biology by functioning like tumor suppressor- or onco- genes and their aberrant expression are associated with the pathogenesis of several neoplasms with overwhelming clinical implications. Since miRNA signature is tissue specific, here, we focused on current data concerning the miRNAs aberrations in GBC pathogenesis. In GBC, miRNAs with tumor suppressor activity (miR-135-5p, miR-335, miR-34a, miR-26a, miR-146b-5p, Mir-218-5p, miR-1, miR-145, mir-130a) were found downregulated, while those with oncogenic property (miR-20a, miR-182, mir-155) were upregulated. The expression profile of miRNAs was significantly associated with GBC prognosis and prediction, and forced over-expression/ inhibition of these miRNAs was shown to affect tumor growth and development. Further, differential expression of miRNAs in the blood samples of GBC patients suggest miRNAs as promising noninvasive biomarker. Thus, miRNAs represent potential candidate for GBC management, though many hurdles need to be overcome before miRNAs therapy can be clinically applied to GBC prevention and treatment.

CCAT1 is an enhancer-templated RNA that predicts BET sensitivity in colorectal cancer

Colon tumors arise in a stepwise fashion from either discrete genetic perturbations or epigenetic dysregulation. To uncover the key epigenetic regulators that drive colon cancer growth, we used a CRISPR loss-of-function screen and identified a number of essential genes, including the bromodomain and extraterminal (BET) protein BRD4. We found that BRD4 is critical for colon cancer proliferation, and its knockdown led to differentiation effects in vivo. JQ1, a BET inhibitor, preferentially reduced growth in a subset of epigenetically dysregulated colon cancers characterized by the CpG island methylator phenotype (CIMP). Integrated transcriptomic and genomic analyses defined a distinct superenhancer in CIMP+ colon cancers that regulates cMYC transcription. We found that the long noncoding RNA colon cancer-associated transcript 1 (CCAT1) is transcribed from this superenhancer and is exquisitely sensitive to BET inhibition. Concordantly, cMYC transcription and cell growth were tightly correlated with the presence of CCAT1 RNA in a variety of tumor types. Taken together, we propose that CCAT1 is a clinically tractable biomarker for identifying patients who are likely to benefit from BET inhibitors.

The long noncoding RNA colon cancer-associated transcript-1/miR-490 axis regulates gastric cancer cell migration by targeting hnRNPA1

Colon cancer-associated transcript-1 (CCAT1) is a highly conserved long noncoding RNA that is deregulated in several cancers. However, its role in gastric carcinoma and its post-transcriptional regulation remain poorly understood. In this study, we provide the first evidence that CCAT1 regulates miR-490 in gastric cancer (GC) cells. Interestingly, miR-490 can also repress CCAT1 expression. CCAT1 expression was significantly upregulated, and miR-490 expression was downregulated in GC. The negative correlation between miR-490 and CCAT1 expression was observed in GC tissues. Importantly, CCAT1 contains a putative miR-490-binding site, and deletion of this binding site abolishes their miR-490 responsiveness. Post-transcriptional CCAT1 silencing by miR-490 significantly suppressed GC cell migration. Furthermore, miR-490 directly bound to the hnRNPA1 mRNA 3'-UTR to repress its translation. Inhibition of miR-490 rescued CCAT1 siRNA-mediated suppression of cell migration. hnRNPA1 expression was significantly upregulated in GC specimens, and there was a negative correlation between miR-490 and hnRNPA1 expression and also a positive correlation between hnRNAP1 expression level and CCAT1 level. Taken together, we show for the first time that the CCAT1/miR-490/hnRNPA1 axis promotes GC migration, and it may have a possible diagnostic and therapeutic potential in GC.

Long non-coding RNAs: emerging players in osteosarcoma

Osteosarcoma is the most common kind of primary bone tumors with high morbidity in infants and adolescents. While the molecular mechanism of osteosarcoma has gained considerable attention, the mechanisms underlying its initiation and progression remain unclear. Recent studies have discovered that long non-coding RNAs (lncRNAs) play an important role in multiply biological processes including cell development, differentiation, proliferation, invasion, and migration. Deregulated expression of lncRNAs has been found in cancers including osteosarcoma. This review summarized the deregulation and functional role of lncRNAs in osteosarcoma and their potential application for diagnosis and treatment of osteosarcoma.

LncRNAs: key players and novel insights into cervical cancer

Cervical cancer contributed the second highest number of deaths in female cancers, exceeded only by breast cancer, carrying high risks of morbidity and mortality. There was a great need and urgency in searching novel treatment targets and prognosis biomarkers to improve the survival rate of cervical cancer patients. Many long non-coding RNAs (lncRNAs) were emerging as pivotal regulators in various biological processes and took vitally an effect on the oncogenesis and progression of cervical cancer. In this review, we summarized the origin and overview function of lncRNAs; highlighted the roles of lncRNAs in cervical cancer in terms of prognosis and tumor progression, invasion and metastasis, apoptosis, and radio-resistance; and outlined the molecular mechanisms of lncRNAs in cervical cancer from the aspects of the interaction of lncRNAs with proteins/mRNAs (especially in HPV protein) and miRNAs, as well as RNA N-methyladenosine (m6A) methylation of lncRNAs. Meanwhile, the application of lncRNAs as biomarkers in cervical cancer prognosis and predictors for metastasis was also discussed. An overview of these researches will be valuable for broadening horizons into mechanisms, selection of meritorious biomarkers for diagnosis as well as prognosis, and future targeted therapy of cervical cancer.

Polymorphisms in lncRNA HOTAIR and susceptibility to breast cancer in a Chinese population

Controversial data have emerged on the association between cancer risk and the single-nucleotide polymorphism (SNP, rs920778C>T) in Hox transcript antisense RNA (HOTAIR). No data on the association between HOTAIR polymorphism and breast cancer (BC) susceptibility and reproductive factors have been reported in China. In this study we investigated the association between HOTAIR polymorphisms and BC susceptibility in a population-based case-control study of 502 cases and 504 matched controls in China. Three haplotype tagging SNPs (rs1899663, rs4759314, rs920778) of HOTAIR were genotyped with polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP) and created-restriction-site PCR (CRS-RFLP) assays. False-positive report probability (FPRP) was calculated to test for false-positive associations. Interactions between the SNPs and reproductive factors were further evaluated by the multifactor dimensionality reduction (MDR) method. BC risk reduction was confined to subgroups of age at menarche >14 (OR: 0.42, 95%CI: 0.21, 0.82) and number of pregnancies >2 (OR: 0.65, 95%CI: 0.49, 0.95) for GT+TT rs1899663, and age at menopause ≤ 50 (OR: 0.97, 95%CI: 0.84, 0.99) for AG+GG rs4759314. Subjects with Trs920778 had a significantly increased risk of breast cancer (OR: 1.41, 95%CI: 1.13, 1.75). We observed a significant interaction between rs920778 and reproductive factors, including age at menopause, number of abortions, and family history. Our results were unlikely to be false positives according to FPRP calculation. In conclusion, genetic variant rs920778 in HOTAIR significantly increased the risk of BC, and it may have apparent interaction with reproductive factors in the progression on BC. These findings extend available data on the association between HOTAIR polymorphisms and BC susceptibility.

Hypoxia/lncRNA-AK123072/EGFR pathway induced metastasis and invasion in gastric cancer

OBJECTIVE

To investigate the role of long noncoding RNAs (lncRNAs) in hypoxia-induced gastric cancer (GC) metastasis and invasion.

METHODS

We investigated the differentially expressed lncRNAs resulting from hypoxia-induced GC and normoxia conditions using microarrays and validated our results through real-time quantitative polymerase chain reaction. The role of the targeting lncRNA was further detected by in vivo and in vitro assays.

RESULTS

We found an lncRNA, AK123072, which was up-regulated by hypoxia. AK123072 was frequently up-regulated in GC samples and promoted GC migration and invasion in vivo and in vitro. Furthermore, AK123072 could mediate the metastasis of hypoxia-induced GC cells. Next, we identified EGFR, which was a metastasis-related gene regulated by AK123072. In addition, we found that the expression of EGFR was positively correlated with that of AK123072 in the clinical GC samples used in our study. Furthermore, we found that the EGFR gene CpG island methylation was significantly increased in GC cells depleted of AK123072. Intriguingly, EGFR expression was also increased by hypoxia, and EGFR up-regulation by AK123072 mediated hypoxia-induced GC cell metastasis.

CONCLUSION

Our results identified hypoxia/lncRNA-AK123072/EGFR pathway in gastric cancer pathogenesis and this might help in the development of new therapeutics in clinics.

The Role of Long Intergenic Noncoding RNA p21 in Vascular Endothelial Cells

Large intergenic long noncoding RNA p21 (lincRNA-p21) has recently shown to play an important role in biological functions. However, the biological role of lincRNA-p21 in vascular endothelial cells remains unclear. In the present study, we investigated the role of lincRNA-p21 in vascular endothelial cells through gain- and loss-of-function studies and found that lincRNA-p21 promoted cell apoptosis and induced cell cycle progression. Furthermore, lincRNA-p21 acted as an endogenous sponge by directly binding to miR-130b and decreased miR-130b expression. In addition, miR-130b reversed the inhibitory effect of lincRNA-p21 on the growth of vascular endothelial cells. Taken together, our data highlight the pivotal role of lincRNA-p21 in the growth of vascular endothelial cells.

Prognostic value of long noncoding RNA MALAT1 in digestive system malignancies

BACKGROUND

MALAT1, a newly discovered long noncoding RNA (lncRNA), has been reported to be highly expressed in many types of cancers. This meta-analysis summarizes its potential prognostic value in digestive system malignancies.

METHODS

A quantitative meta-analysis was performed through a systematic search in PubMed, Cochrane Library, Web of Science and Chinese National Knowledge Infrastructure (CNKI) for eligible papers on the prognostic impact of MALAT1 in digestive system malignancies from inception to Apr. 25, 2015. Pooled hazard ratios (HRs) with 95% confidence interval (95% CI) were calculated to summarize the effect.

RESULTS

Five studies were included in the study, with a total of 527 patients. A significant association was observed between MALAT1 abundance and poor overall survival (OS) of patients with digestive system malignancies, with pooled hazard ratio (HR) of 7.68 (95% confidence interval [CI]: 4.32-13.66, P<0.001). Meta sensitivity analysis suggested the reliability of our findings. No publication bias was observed.

CONCLUSIONS

MALAT1 abundance may serve as a novel predictive factor for poor prognosis in patients with digestive system malignancies.

Roles of competing endogenous RNAs in gastric cancer

Long noncoding RNA (lncRNA) is >200 nucleotides long and lacks coding ability. LncRNA was regarded as transcript noise, until emerging results showed its roles in development, homeostasis and carcinogenesis. LncRNAs containing microRNA (miRNA) response elements could compete with the miRNA target gene and regulate its expression through decreasing free functional miRNA. Such lncRNA is called competing endogenous RNA (ceRNA), and the 'lncRNA-miRNA' interaction appreciably enriches the world of RNA-RNA regulation. Gastric cancer involves dysregulation of both protein-coding genes and noncoding genes, and the ceRNA regulatory mechanism may participate in this pathogenic process. In this review, we discuss recent findings on the roles of ceRNAs in gastric carcinogenesis.

Long non-coding RNA Fer-1-like protein 4 suppresses oncogenesis and exhibits prognostic value by associating with miR-106a-5p in colon cancer

Novel long non-coding RNA Fer-1-like protein 4 (FER1L4) has been confirmed to play crucial regulatory roles in tumor progression. It exerts an impact on tumor suppression and functions as a competing endogenous RNA (ceRNA) by sponging miR-106a-5p in gastric cancer. However, its clinical significance in colon cancer is completely unknown. The aim of the present study was to annotate the role of FER1L4 and its clinical value in colon cancer. The results showed the aberrant expression of FER1L4 and miR-106a-5p in colon cancer tissues. In addition, significant negative correlation between FER1L4 and miR-106a-5p expression levels was observed. Among the colon cancer cell lines, FER1L4 levels were relatively lower, with concurrent high levels of miR-106a-5p. Restoration of FER1L4 decreased the expression of miR-106a-5p, and had a significant influence on colon cancer cell proliferation, migration and invasion. The FER1L4 expression was correlated with depth of tumor invasion, lymph node metastasis, vascular invasion and clinical stage. Moreover, striking differences in overall survival and disease-free survival were observed for the cases with both low FER1L4 expression and high miR-106a-5p expression compared with cases with high FER1L4 expression and low miR-106a-5p expression. Circulating FER1L4 and miR-106a-5p levels were decreased and increased, respectively, in colon cancer patients after surgery. Our findings indicated that FER1L4 could exert a tumor suppressive impact on colon cancer, which at least, in part, through suppressing miR-106a-5p expression, and depletion of FER1L4, alone or combined with overexpression of miR-106a-5p, is predictive of poor prognosis in colon cancer and may play a crucial role in cancer prevention and treatment.

The lncRNA MALAT1 protects the endothelium against ox-LDL-induced dysfunction via upregulating the expression of the miR-22-3p target genes CXCR2 and AKT

CXCR2 plays a key role in protecting the integrity of the endothelium. Emerging evidence has demonstrated that the long ncRNAs (lncRNA) Human metastasis associated lung adenocarcinoma transcript 1 (MALAT1) participates in the regulation of the pathophysiological processes. However, whether there is crosstalk between CXCR2 and MALAT1 remains unknown. In this study, we demonstrated that MALAT1 was upregulated in patients with unstable angina. MALAT1 silencing significantly downregulated the expression of the miR-22-3p target gene CXCR2 via reversing the effect of the miR-22-3p, resulting in the aggravation of Oxidized low-density lipoprotein (ox-LDL)-induced endothelial injury; this process was associated with the AKT pathway. Thus, MALAT1 protects the endothelium from ox-LDL-induced endothelial dysfunction partly through competing with miR-22-3p for endogenous RNA.

The long noncoding RNA regulation at the MYC locus

Aberrant expression of long noncoding RNAs (lncRNAs) has been linked to cancers. The MYC oncoprotein is a key contributor to the development of many human tumors. Recent studies have revealed that a number of lncRNAs originating from the human 8q24 locus previously known to corresponding to a 'gene desert' are transcribed and play important roles in MYC regulation. In this review, we highlight recent progress in how these lncRNAs participate in control of MYC levels in normal and tumor cells.

Long noncoding RNA NEAT1 promotes glioma pathogenesis by regulating miR-449b-5p/c-Met axis

Growing evidence demonstrates that long noncoding RNAs (lncRNAs) are involved in the progression of various cancers including glioma. Nuclear enriched abundant transcript 1 (NEAT1), an essential lncRNA for the formation of nuclear body paraspeckles, was not fully explored in glioma. We aimed to determine the expression, roles, and functional mechanisms of NEAT1 in the progression of glioma. By real-time PCR, we suggested that NEAT1 was upregulated in glioma tissues than noncancerous brain tissues. Knockdown of NEAT1 reduced glioma cell proliferation, invasion, and migration. RNA immunoprecipitation assay combined with luciferase reporter assay confirmed miR-449b-5p-specific binding to NEAT1. Furthermore, we verified that c-Met was a directly target of miR-449b-5p. Rescue assays demonstrated NEAT1 functions a molecular sponge for miR-449b-5p and leads to the upregulation of c-Met. This regulation menchaism promotes glioma pathogenesis and may provide a potential target for the prognosis and treatment of glioma.

Overexpression of long non-coding RNA CCAT1 is a novel biomarker of poor prognosis in patients with breast cancer

INTRODUCTION

Recent studies have demonstrated that lncRNA CCAT1 was increased in many types of cancers and was involved in various cellular processes related to carcinogenesis. However, the clinical significance and prognostic value of lncRNA CCAT1 in breast cancer (BC) haven't been investigated.

METHODS

Expression levels of lncRNA CCAT1 in 92 pairs of BC cancer tissues and adjacent normal tissues were detected by quantitative real-time PCR. In order to determine its prognostic value, overall survival and progression-free survival were evaluated using the Kaplan-Meier method, and multivariate analysis was performed using the Cox proportional hazard analysis.

RESULTS

Expression levels of lncRNA CCAT1 in BC tissues were significantly higher than those in adjacent normal tissues. High expression of lncRNA CCAT1 was associated with differentiation grade, TNM stage, and lymph node metastases. Kaplan-Meier analysis with the log-rank test indicated that high expression of lncRNA CCAT1 had a decreased overall survival and progression-free survival. Multivariable analysis was further identified high expression of lncRNA CCAT1 as an independent prognosis factor for overall survival and progression-free survival.

CONCLUSIONS

Our findings provided that the expression of lncRNA CCAT1 was up-regulated in BC and associated with overall survival as well as progression-free survival, suggesting that lncRNA CCAT1 could be a potential prognostic biomarker for BC progression.

Long noncoding RNAs in development and cancer: potential biomarkers and therapeutic targets

Long noncoding RNAs are emerging as key players in various fundamental biological processes. We highlight the varied molecular mechanisms by which lncRNAs modulate gene expression in diverse cellular contexts and their role in early mammalian development in this review. Furthermore, it is being increasingly recognized that altered expression of lncRNAs is specifically associated with tumorigenesis, tumor progression and metastasis. We discuss various lncRNAs implicated in different cancer types with a focus on their clinical applications as potential biomarkers and therapeutic targets in the pathology of diverse cancers.

Long noncoding RNAs in development and cancer: potential biomarkers and therapeutic targets

Long noncoding RNAs are emerging as key players in various fundamental biological processes. We highlight the varied molecular mechanisms by which lncRNAs modulate gene expression in diverse cellular contexts and their role in early mammalian development in this review. Furthermore, it is being increasingly recognized that altered expression of lncRNAs is specifically associated with tumorigenesis, tumor progression and metastasis. We discuss various lncRNAs implicated in different cancer types with a focus on their clinical applications as potential biomarkers and therapeutic targets in the pathology of diverse cancers.

MicroRNA expression and its implications for diagnosis and therapy of gallbladder cancer

Gallbladder cancer is the most common biliary tract malignancy with poor prognosis. MicroRNAs (miRNAs) are a class of small, endogenous, non-coding RNAs of 19-23 nucleotides in length, which regulate gene expression at post-transcriptional and translational levels. Several studies have demonstrated aberrant expression of miRNAs in gallbladder cancer tissues. Recent evidences also demonstrated that specific miRNAs are functionally involved in gallbladder cancer development through modulating cell proliferation, apoptosis, migration, invasion and metastasis. In this review, we explore the possibilities of using miRNAs as prognostic, diagnostic markers and therapeutic targets in gallbladder cancer.