HOTAIR, a prognostic factor in esophageal squamous cell carcinoma, inhibits WIF-1 expression and activates Wnt pathway

De-repressing LncRNA-Targeted Genes to Upregulate Gene Expression: Focus on Small Molecule Therapeutics

Non-protein coding RNAs (ncRNAs) make up the overwhelming majority of transcripts in the genome and have recently gained attention for their complex regulatory role in cells, including the regulation of protein-coding genes. Furthermore, ncRNAs play an important role in normal development and their expression levels are dysregulated in several diseases. Recently, several long noncoding RNAs (lncRNAs) have been shown to alter the epigenetic status of genomic loci and suppress the expression of target genes. This review will present examples of such a mechanism and focus on the potential to target lncRNAs for achieving therapeutic gene upregulation by de-repressing genes that are epigenetically silenced in various diseases. Finally, the potential to target lncRNAs, through their interactions with epigenetic enzymes, using various tools, such as small molecules, viral vectors and antisense oligonucleotides, will be discussed. We suggest that small molecule modulators of a novel class of drug targets, lncRNA-protein interactions, have great potential to treat some cancers, cardiovascular disease, and neurological disorders.

Long noncoding RNA expression in dermal papilla cells contributes to hairy gene regulation

Dermal papilla (DP) cells may be the source of dermal-derived signaling molecules involved in hair-follicle development and postnatal hair cycling. Early-passage DP cells can induce hair growth in vivo, but, on further culture, this ability is lost. The cellular mechanisms underlying the hair-follicle induction property of early-passage DP cells are unclear. Long noncoding RNAs (lncRNAs) are an important class of genes involved in various biological functions. They are aberrantly expressed and play roles in the regulation of the Wnt signaling pathway, a critical point in maintaining hair-induction activity. LncRNA microarray revealed 1683 upregulated and 1773 downregulated lncRNAs in passage-4 DP cells compare with passage-10 DP cells. To investigate the relation between lncRNAs and coding genes in WNT signaling, we constructed a coding-noncoding gene co-expression network using lncRNAs and coding genes that were differentially expressed between the passage-4 and -10 DP cells. RP11-766N7.3, H19 and HOTAIR are specific lncRNAs that were aberrantly expressed in DP cells and played an important role in regulating Wnt signaling. This study may provide potential targets for discovering the hair-follicle induction mechanism of early-passage DP cells.

Prognostic value of long non-coding RNA HOTAIR in various cancers

Long non-coding RNA has been involved in cancer progression, and high HOX transcript antisense intergenic RNA (HOTAIR) is thought to be a poor prognostic indicator in tumorigenesis of multiple types of cancer. Hence, the present study further reveals its prognostic value in tumor malignancy. A systematic review of PubMed and Web of Science was carried out to select literatures relevant to the correlation between HOTAIR expression levels and clinical outcome of various tumors. Overall survival (OS), metastasis-free survival (MFS), recurrence-free survival (RFS), and disease-free survival (DFS) were subsequently analyzed. Data from studies directly reporting a hazard ratio (HR) and the corresponding 95% confidence interval (CI) or a P value as well as survival curves were pooled in the current meta-analysis. A total of 2255 patients from 19 literatures almost published in 2011 or later were included in the analysis. The results suggest that HOTAIR was highly associated with HR for OS of 2.33 (95%CI = 1.77-3.09, Pheterogeneity = 0.016). Stratified analyses indicate that elevated levels of HOTAIR appears to be a powerful prognostic biomarker for patients with colorectal cancer (HR = 3.02, 95CI% = 1.84-4.95, Pheterogeneity = 0.699) and esophageal squamous cell carcinomas (HR = 2.24, 95CI% = 1.67-3.01, Pheterogeneity = 0.711), a similar effect was also observed in analysis method and specimen, except for ethnicity. In addition, Hazard ratios for up-regulation of HOTAIR for MFS, RFS, and DFS were 2.32 (P<0.001), 1.98 (P = 0.369), and 3.29 (P = 0.001), respectively. In summary, the high level of HOTAIR is intimately associated with an adverse OS in numerous cancers, suggesting that HOTAIR may act as a potential biomarker for the development of malignancies.

Molecular function and regulation of long non-coding RNAs: paradigms with potential roles in cancer

Different long non-coding RNAs (lncRNAs) are transcribed within the genome. Although initially argued to be spurious transcriptional noise, these RNAs play important roles in biological pathways, as shown by different studies. Also, there are some reports about the role of lncRNAs in different cancers. They can contribute to the development and progression of cancer by the functioning as oncogene or/and tumor suppressor molecules. In this review, we point to some important lncRNAs as examples which seem to be involved in cancer initiation/progression.

Long non-coding RNA profiling in laryngeal squamous cell carcinoma and its clinical significance: potential biomarkers for LSCC

Long non-coding RNAs (lncRNAs) are novel transcripts that may play important roles in cancer. Our study aimed to resolve the lncRNA profile of larynx squamous cell carcinoma (LSCC) and to determine its clinical significance. The global lncRNA expression profile in LSCC tissues was measured by lncRNA microarray. Distinctly expressed lncRNAs were identified and levels of AC026166.2-001 and RP11-169D4.1-001 lncRNAs in 87 LSCC samples and paired adjacent normal tissue were analyzed by real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). The clinical significance of these lncRNAs in laryngeal cancer was analyzed and survival data were estimated by the Kaplan–Meier method and the log-rank test. A receiver operating characteristic (ROC) curve was constructed to check the diagnostic value. In the lncRNA expression profile of tumor samples, 684 lncRNAs were upregulated and 747 lncRNAs were downregulated (fold-change >2.0). Of these, AC026166.2-001 and RP11-169D4.1-001 were distinctly dysregulated, with AC026166.2-001 exhibiting lower expression in cancer tissues and RP11-169D4.1-001 higher expression. We verified that both AC026166.2-001 and RP11-169D4.1-001 were expressed at a lower level in cervical lymph nodes compared with paired laryngeal cancer tissues and paired normal tissues. RP11-169D4.1-001 levels were positively correlated with lymph node metastasis (P = 0.007). From the survival analysis, decreased levels of AC026166.2-001 and RP11-169D4.1-001 were associated with poorer prognosis. The area under the ROC curve was up to 0.65 and 0.67, respectively, and the cut-off point of ΔCt was 11.23 and 10.53, respectively. AC026166.2-001 and RP11-169D4.1-001 may act as novel biomarkers in LSCC and may be potential therapeutic targets for LSCC patients. Both AC026166.2-001 and RP11-169D4.1-001 could be independent prognostic factors for survival in LSCC.

Long non-coding RNAs: the epigenetic regulators involved in the pathogenesis of reproductive disorder

Long non-coding RNAs (lncRNAs) are long single-stranded RNAs without translation potential. LncRNAs function in regulating epigenetic and cellular processes through various mechanisms. Nowadays, rapidly growing evidence has shown that abnormally expressed lncRNAs were involved in various inflammation-related states or diseases. Abnormal inflammation responses contribute to reproductive pathology and play vital roles in developing most disorders of the female reproductive system. In this review, we discussed the history of ncRNAs including lncRNAs, methodologies for lncRNA identification, mechanisms of lncRNA expression and regulation and mainly discussed the expression and function of lncRNAs in the female reproductive system with special focus on the inflammation and infection pathway. By analyzing the present available studies of lncRNA transcripts within the reproductive system and the current understanding of the biology of lncRNAs, we have suggested the important diagnostic and therapeutic roles of lncRNAs in the etiology of reproductive disorders.

Long non-coding RNAs involved in gynecological cancer

Long non-coding RNAs (lncRNAs) are defined as transcripts longer than 200 nucleotides with little or no protein-coding capacity. Previously, they were considered transcription byproducts without biological functions. Further studies have shown that lncRNAs are involved in multiple biological and pathological processes, including regulation of epigenetic, transcriptional, and posttranscriptional events. Long non-coding RNA expression patterns in various malignant tumors differ from those of benign tumors and normal tissue, and such alterations may promote or suppress tumorigenesis and cancer progression. The expression profiles of lncRNAs are abnormal in gynecological cancers, such as ovarian cancer, cervical cancer, and endometrial cancer, suggesting an important role for lncRNAs in tumorigenesis/progression of these cancers. Here, we summarized the research progress on identifying the biological functions of lncRNAs in tumorigenesis, progression, and metastasis in gynecological cancers. We provide references for exploring the clinical applications of lncRNAs as early diagnostic biomarkers or ideal therapeutic targets in gynecological cancers.

Long noncoding RNA HOTAIR as an independent prognostic marker in cancer: a meta-analysis

BACKGROUND

HOTAIR, a newly discovered long intergenic noncoding RNA (lincRNA), has been reported to be aberrantly expressed in many types of cancers. This meta-analysis summarizes its potential role as a biomarker in malignancy.

METHODS

A quantitative meta-analysis was performed through a systematic search in Pubmed, Medline and Web of Science for eligible papers on the prognostic impact of HOTAIR in cancer from inception to Feb. 28, 2014. Pooled hazard ratios (HRs) with 95% confidence interval (95% CI) were calculated to summarize the effect.

RESULTS

Nineteen studies were included in the study, with a total of 2033 patients. A significant association was observed between high HOTAIR expression and poor overall survival (OS) in patients with cancer (pooled HR 2.22, 95% CI: 1.68-2.93). Place of residence (Asian or Western countries), type of cancer (digestive or non-digestive disease), sample size (more or less than 100), and paper quality (score more or less than 85%) did not alter the significant predictive value of HOTAIR in OS from various kinds of cancer but preoperative status did. By combining HRs from Cox multivariate analyses, we found that HOTAIR expression was an independent prognostic factor for cancer patients (pooled HR 2.26, 95% CI: 1.62-3.15). Subgroup analysis showed that HOTAIR abundance was an independent prognostic factor for cancer metastasis (HR 3.90, 95% CI: 2.25-6.74). For esophageal carcinoma, high HOTAIR expression was significantly associated with TNM stage (III/IV vs. I/II: OR 6.90, 95% CI: 2.81-16.9) without heterogeneity. In gastric cancer, HOTAIR expression was found to be significantly associated with lymph node metastases (present vs. absent: OR 4.47, 95% CI: 1.88-10.63) and vessel invasion (positive vs. negative: OR 2.88, 95% CI: 1.38-6.04) without obvious heterogeneity.

CONCLUSIONS

HOTAIR abundance may serve as a novel predictive factor for poor prognosis in different types of cancers in both Asian and Western countries.

Epidemiological studies of esophageal cancer in the era of genome-wide association studies

Esophageal cancer (EC) caused about 395000 deaths in 2010. China has the most cases of EC and EC is the fourth leading cause of cancer death in China. Esophageal squamous cell carcinoma (ESCC) is the predominant histologic type (90%-95%), while the incidence of esophageal adenocarcinoma (EAC) remains extremely low in China. Traditional epidemiological studies have revealed that environmental carcinogens are risk factors for EC. Molecular epidemiological studies revealed that susceptibility to EC is influenced by both environmental and genetic risk factors. Of all the risk factors for EC, some are associated with the risk of ESCC and others with the risk of EAC. However, the details and mechanisms of risk factors involved in the process for EC are unclear. The advanced methods and techniques used in human genome studies bring a great opportunity for researchers to explore and identify the details of those risk factors or susceptibility genes involved in the process of EC. Human genome epidemiology is a new branch of epidemiology, which leads the epidemiology study from the molecular epidemiology era to the era of genome wide association studies (GWAS). Here we review the epidemiological studies of EC (especially ESCC) in the era of GWAS, and provide an overview of the general risk factors and those genomic variants (genes, SNPs, miRNAs, proteins) involved in the process of ESCC.

lincRNA HOTAIR as a novel promoter of cancer progression

Large intergenic non-coding RNAs (lincRNA) regulate development and disease via interactions with their protein partners. Expression of the lincRNA HOX transcript antisense RNA (HOTAIR) is elevated in a variety of malignancies and linked to metastasis and poor prognosis. HOTAIR promotes proliferation, invasion, and metastasis in the preclinical studies of cancer through modulation of chromatin modifying complexes. In the current review we discuss the molecular mechanisms of HOTAIR-mediated aggressive phenotypes of cancer, HOTAIR's potential in cancer intervention, and challenges in exploration of HOTAIR in cancer biology.

Transforming growth factor-β-induced lncRNA-Smad7 inhibits apoptosis of mouse breast cancer JygMC(A) cells

Transforming growth factor (TGF)-β exhibits both pro-apoptotic and anti-apoptotic effects on epithelial cells in a context-dependent manner. The anti-apoptotic function of TGF-β is mediated by several downstream regulatory mechanisms, and has been implicated in the tumor-progressive phenotype of breast cancer cells. We conducted RNA sequencing of mouse mammary gland epithelial (NMuMG) cells and identified a long non-coding RNA, termed lncRNA-Smad7, which has anti-apoptotic functions, as a target of TGF-β. lncRNA-Smad7 was located adjacent to the mouse Smad7 gene, and its expression was induced by TGF-β in all of the mouse mammary gland epithelial cell lines and breast cancer cell lines that we evaluated. Suppression of lncRNA-Smad7 expression cancelled the anti-apoptotic function of TGF-β. In contrast, forced expression of lncRNA-Smad7 rescued apoptosis induced by a TGF-β type I receptor kinase inhibitor in the mouse breast cancer cell line JygMC(A). The anti-apoptotic effect of lncRNA-Smad7 appeared to occur independently of the transcriptional regulation by TGF-β of anti-apoptotic DEC1 and pro-apoptotic Bim proteins. Small interfering RNA for lncRNA-Smad7 did not alter the process of TGF-β-induced epithelial-mesenchymal transition, phosphorylation of Smad2 or expression of the Smad7 gene, suggesting that the contribution of this lncRNA to TGF-β functions may be restricted to apoptosis. Our findings suggest a complex mechanism for regulating the anti-apoptotic and tumor-progressive aspects of TGF-β signaling.

Upregulation of the long noncoding RNA HOTAIR predicts recurrence in stage Ta/T1 bladder cancer

Stage Ta/T1 urothelial carcinoma of the bladder (Ta/T1 BC) has a marked tendency to recurrence. Long noncoding RNA HOTAIR has been reported to be expressed in some human cancers such as breast cancer, and it may be positively correlated with patient's prognosis. The aim of our study was to evaluate the prognostic value of HOTAIR in Ta/T1 BC. HOTAIR expression in Ta/T1 BC tissues and adjacent normal tissues was collected from 110 patients and measured by real-time quantitative PCR. The relationships between HOTAIR and the clinical pathological characteristics of Ta/T1 BC patients were analyzed. Immunohistochemistry was done to detect the protein of Wnt inhibitory factor 1 (WIF-1) as well. Ninety out of 110 specimens were detected in HOTAIR high expression. Histological grade and expression levels of HOTAIR were positively correlated with the recurrence rate. HOTAIR expression (hazard ratio 4.712; 95 % CI 2.894-8.714; P < 0.001) was an independent predictor of recurrence rate in multivariate Cox regression analysis. HOTAIR expression is correlated with patients' poor prognosis. A significant inverse correlation between HOTAIR and WIF-1 expression was demonstrated in Ta/T1 BC tissues. The expression levels of HOTAIR are an independent prognostic factor of recurrence in Ta/T1 BC patients.

Histones and long non-coding RNAs: the new insights of epigenetic deregulation involved in oral cancer

Oral squamous cell carcinoma (OSCC) is a category of aggressive malignancies that represent clinically, molecularly, and etiologically heterogeneous tumors. The majority of OSCCs are associated with tobacco and alcohol use, acting both independently and synergistically, which suggests that the environment plays an important role in carcinogenesis; however, the mechanisms associated with the development of OSCC are not well understood. It has been proposed that the epigenetic components could be implicated in the initiation and progression of OSCC. Primarily, aberrant DNA methylation patterns have been widely addressed in the study of OSCC. Diverse studies have proposed that other epigenetic processes such as post-translational histone modification, the deposition of histone variants, histone chaperones, and recently non-coding RNA, can be also involved in the development of oral cancer. In this review we focus on describing the new insights of the epigenetics processes that are related with OSCC as histones variants and long non-coding RNAs.

Long non-coding RNAs as novel biomarkers and therapeutic targets in head and neck cancers

Long non-coding RNAs (lncRNAs) are generally defined as RNA molecules greater than 200 nt in length and without protein-coding property that different from housekeeping RNAs such as tRNAs, rRNAs, and snRNAs, and independent from small RNAs with specific molecular processing machinery such as micro- or piwi-RNAs. LncRNAs are a novel class of mRNA-like transcripts which contribute to cancer development and progression and accelerate cancer cells proliferation, invasion, metastasis, and apoptosis. These research results indicate the potential of lncRNAs as prospective novel biomarkers for diagnosis, therapeutic targets and prognosis for cancers. In this review, we synthesize present study results to highlight aberration of lncRNAs in various types of head and neck cancers, and try to clarify the molecular mechanisms of lncRNAs affecting the oncogenesis and progression of head and neck cancer, as well as pay particular attention to provide a new avenue to the diagnosis and treatment strategy.

Long non-coding RNA HOTAIR promotes cell migration and invasion via down-regulation of RNA binding motif protein 38 in hepatocellular carcinoma cells

Long non-coding RNA HOTAIR exerts regulatory functions in various biological processes in cancer cells, such as proliferation, apoptosis, mobility, and invasion. We previously found that HOX transcript antisense RNA (HOTAIR) is a negative prognostic factor and exhibits oncogenic activity in hepatocellular carcinoma (HCC). In this study, we aimed to investigate the role and molecular mechanism of HOTAIR in promoting HCC cell migration and invasion. Firstly, we profiled its gene expression pattern by microarray analysis of HOTAIR loss in Bel-7402 HCC cell line. The results showed that 129 genes were significantly down-regulated, while 167 genes were significantly up-regulated (fold change >2, p < 0.05). Bioinformatics analysis indicated that RNA binding proteins were involved in this biological process. HOTAIR suppression using RNAi strategy with HepG2 and Bel-7402 cells increased the mRNA and protein expression levels of RNA binding motif protein 38 (RBM38). Moreover, the expression levels of RBM38 in HCC specimens were significantly lower than paired adjacent noncancerous tissues. In addition, knockdown of HOTAIR resulted in a decrease of cell migration and invasion, which could be specifically rescued by down-regulation of RBM38. Taken together, HOTAIR could promote migration and invasion of HCC cells by inhibiting RBM38, which indicated critical roles of HOTAIR and RBM38 in HCC progression.

Long non-coding RNA HOTAIR promotes cell migration and invasion via down-regulation of RNA binding motif protein 38 in hepatocellular carcinoma cells

Long non-coding RNA HOTAIR exerts regulatory functions in various biological processes in cancer cells, such as proliferation, apoptosis, mobility, and invasion. We previously found that HOX transcript antisense RNA (HOTAIR) is a negative prognostic factor and exhibits oncogenic activity in hepatocellular carcinoma (HCC). In this study, we aimed to investigate the role and molecular mechanism of HOTAIR in promoting HCC cell migration and invasion. Firstly, we profiled its gene expression pattern by microarray analysis of HOTAIR loss in Bel-7402 HCC cell line. The results showed that 129 genes were significantly down-regulated, while 167 genes were significantly up-regulated (fold change >2, p < 0.05). Bioinformatics analysis indicated that RNA binding proteins were involved in this biological process. HOTAIR suppression using RNAi strategy with HepG2 and Bel-7402 cells increased the mRNA and protein expression levels of RNA binding motif protein 38 (RBM38). Moreover, the expression levels of RBM38 in HCC specimens were significantly lower than paired adjacent noncancerous tissues. In addition, knockdown of HOTAIR resulted in a decrease of cell migration and invasion, which could be specifically rescued by down-regulation of RBM38. Taken together, HOTAIR could promote migration and invasion of HCC cells by inhibiting RBM38, which indicated critical roles of HOTAIR and RBM38 in HCC progression.

HOTAIR, a prognostic factor in esophageal squamous cell carcinoma, inhibits WIF-1 expression and activates Wnt pathway

Long non-coding RNAs (LncRNAs) have been recently found to be pervasively transcribed in the genome and critical regulators of the epigenome. HOTAIR, as a well-known LncRNA, has been found to play important roles in several tumors. Herein, the clinical application value and biological functions of HOTAIR were focused and explored in esophageal squamous cell carcinoma (ESCC). It was found that there was a great upregulation of HOTAIR in ESCC compared to their adjacent normal esophageal tissues. Meanwhile, patients with high HOTAIR expression have a significantly poorer prognosis than those with low expression. Moreover, HOTAIR was further validated to promote migration and invasion of ESCC cells in vitro. Then some specific molecules with great significance were investigated after HOTAIR overexpression using microarray and quantitative real time-polymerase chain reaction (qPCR). WIF-1 playing an important role in Wnt/β-catenin signaling pathway was selected and further tested by immunehistochemistry. Generally, inverse correlation between HOTAIR and WIF-1 expression was demonstrated both in ESCC cells and tissues. Mechanistically, HOTAIR directly decreased WIF-1 expression by promoting its histone H3K27 methylation in the promoter region and then activated the Wnt/β-catenin signaling pathway. This newly identified HOTAIR/WIF-1 axis clarified the molecular mechanism of ESCC cell metastasis and represented a novel therapeutic target in patients with ESCC.