In addition to mutations or aberrant expression in the protein-coding genes, mutations and misregulation of noncoding RNAs, in particular long noncoding RNAs (lncRNA), appear to play major roles in cancer. Genome-wide association studies of tumor samples have identified a large number of lncRNAs associated with various types of cancer. Alterations in lncRNA expression and their mutations promote tumorigenesis and metastasis. LncRNAs may exhibit tumor-suppressive and -promoting (oncogenic) functions. Because of their genome-wide expression patterns in a variety of tissues and their tissue-specific expression characteristics, lncRNAs hold strong promise as novel biomarkers and therapeutic targets for cancer. In this article, we have reviewed the emerging functions and association of lncRNAs in different types of cancer and discussed their potential implications in cancer diagnosis and therapy. Cancer Res; 77(15); 3965-81. ©2017 AACR.

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Long Noncoding RNA and Cancer: A New Paradigm.

Circular RNAs, a novel class of endogenous noncoding RNAs, are characterized by their covalently closed loop structures without a 5′ cap or a 3′ Poly A tail. Although the mechanisms of circular RNAs’ generation and function are not fully clear, recent research has shown that circular RNAs may function as potential molecular markers for disease diagnosis and treatment and play an important role in the initiation and progression of human diseases, especially in tumours. This review summarizes some information about categories, biogenesis, functions at the molecular level, properties of circular RNAs and the possibility of circular RNAs as biomarkers in cancers.

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CircRNA: functions and properties of a novel potential biomarker for cancer

Circular RNA (circRNA) is a novel member of the noncoding cancer genome with distinct properties and diverse cellular functions, which is being explored at a steadily increasing pace. The list of endogenous circRNAs involved in cancer continues to grow; however, the functional relevance of the vast majority is yet to be discovered. In general, circRNAs are exceptionally stable molecules and some have been shown to function as efficient microRNA sponges with gene-regulatory potential. Many circRNAs are highly conserved and have tissue-specific expression patterns, which often do not correlate well with host gene expression. Here we review the current knowledge on circRNAs in relation to their implications in tumorigenesis as well as their potential as diagnostic and prognostic biomarkers and as possible therapeutic targets in future personalized medicine. Finally, we discuss future directions for circRNA cancer research and current caveats, which must be addressed to facilitate the translation of basic circRNA research into clinical use.

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Circular RNAs in cancer: opportunities and challenges in the field.

Long non-coding RNAs: A new frontier in the study of human diseases

Noncoding RNAs (ncRNAs) constitute the majority of the human transcribed genome. This largest class of RNA transcripts plays diverse roles in a multitude of cellular processes, and has been implicated in many pathological conditions, especially cancer. The different subclasses of ncRNAs include microRNAs, a class of short ncRNAs; and a variety of long ncRNAs (lncRNAs), such as lincRNAs, antisense RNAs, pseudogenes, and circular RNAs. Many studies have demonstrated the involvement of these ncRNAs in competitive regulatory interactions, known as competing endogenous RNA (ceRNA) networks, whereby lncRNAs can act as microRNA decoys to modulate gene expression. These interactions are often interconnected, thus aberrant expression of any network component could derail the complex regulatory circuitry, culminating in cancer development and progression. Recent integrative analyses have provided evidence that new computational platforms and experimental approaches can be harnessed together to distinguish key ceRNA interactions in specific cancers, which could facilitate the identification of robust biomarkers and therapeutic targets, and hence, more effective cancer therapies and better patient outcome and survival.

Noncoding RNA:RNA Regulatory Networks in Cancer.

Homeobox (HOX) transcript antisense RNA (HOTAIR) is a long intergenic noncoding RNA (lincRNA) that is significantly overexpressed in breast and hepatocellular cancers. It remains unclear, however, whether HOTAIR plays an oncogenic role in human laryngeal squamous cell cancer (LSCC). We therefore investigated the expression and functional role of HOTAIR in LSCC. HOTAIR levels were significantly higher in LSCC than in corresponding adjacent non-neoplastic tissues, and patients with poor histological grade or advanced clinical stage had higher HOTAIR expression. Log-rank test showed a significant association between high levels of HOTAIR and poor prognosis in LSCC patients. Multivariate Cox analysis suggested that HOTAIR is an independent prognostic factor of LSCC. siRNA-mediated knockdown of HOTAIR led to reduced invasion and increased apoptosis of Hep-2 cells in vitro and significantly reduced growth of LSCC xenograft tumors in mice. Moreover, PTEN methylation was significantly reduced in Hep-2 cells depleted of HOTAIR. Taken together, these results suggest that the oncogenic role of HOTAIR in LSCC is related to promotion of PTEN methylation. HOTAIR could serve as a marker for LSCC prognosis and a potential target for therapeutic intervention.

Long intergenic noncoding RNA HOTAIR is overexpressed and regulates PTEN methylation in laryngeal squamous cell carcinoma.

Serum exosomes containing noncoding RNA (ncRNA) play an important role in both physiological and pathological conditions. However, biological function of exosomal ncRNA remains unclear. The aim of the study was to investigate the prognostic and diagnostic values of exosomal ncRNA by comparing the amounts of exosomal miR-21 and HOTAIR in serum of laryngeal squamous cell carcinoma (LSCC) patients with those of polyps of vocal cords, and by determinating whether combined detection of the two molecules could provide useful information in the diagnosis of LSCC. Exosomes were isolated from the serum samples of 52 LSCC patients and those of 49 patients with polyps of vocal cords. TEM and Western blot were applied for the confirmation of isolated exosomes by observing the ultra structure and testing CD63 marker protein, respectively. RT-PCR was performed to detect the expression of miR-21 and HOTAIR in the exosomes. The receiver-operating characteristic (ROC) curve was generated to examine the prognostic value of the two molecules. The expression of exosomal miR-21 and HOTAIR was significantly higher in patients with LSCC than those with vocal cord polyps. There were significant differences of serum exosomal miR-21 and HOTAIR expressions between the advanced T classifications (T3/T4) or clinical stages (III/IV) and the early stages. The patients with lymph node metastasis had higher serum exosomal miR-21 and HOTAIR expressions than those without. There were no differences between patient sex, tumor locations and differentiations. The area under the ROC curve of combined examination of exosomal HOTAIR and miR-21 for diagnosing LSCC was 87.6 %, which was significantly higher than 80.1 % of miR-21 (p = 0.0359) or 72.7 % of HOTAIR (p = 0.0012), showing 94.2 and 73.5 % of sensitivity and specificity, respectively, in differentiating the malignant from benign laryngeal disease. Serum exosomal miR-21 and HOTAIR were significantly correlated with clinical parameters of LSCC, and combined evaluation of their serum expressions may be a valuable biomarker to screen LSCC and might be a promising predicting tool for LSCC patient.

Combined detection of serum exosomal miR-21 and HOTAIR as diagnostic and prognostic biomarkers for laryngeal squamous cell carcinoma

Circular RNAs (circRNAs), a class of endogenous RNAs, are characterized by covalently closed continuous loop without 5’ to 3’ polarity and polyadenylated tail. Recent studies indicated that circRNAs might play an important role in cancer. However, the function of circRNA in laryngeal squamous cell cancer tissues (LSCC) is still unknown. In this study, we investigated the expression of circRNAs in 4 paired LSCC tissues and adjacent non-tumor tissues by microarray analysis. Results showed significant upregulation (n = 302) of or downregulation (n = 396) of 698 circRNAs in LSCC tissues. We further detected hsa_circRNA_100855 as the most upregulated circRNA and hsa_circRNA_104912 as the most downregulated circRNA using qRT-PCR methods. Results showed that hsa_circRNA_100855 level was significantly higher in LSCC than in the corresponding adjacent non-neoplastic tissues. Patients with T3-4 stage, neck nodal metastasis or advanced clinical stage had higher hsa_circRNA_100855 expression. The hsa_circRNA_104912 level was significantly lower in LSCC than in corresponding adjacent non-neoplastic tissues. Patients with T3-4 stage, neck nodal metastasis, poor differentiation or advanced clinical stage had a lower hsa_circRNA_104912 expression. Overall, our data suggest that circRNAs play an important role in the tumorigenesis of LSCC and may serve as novel and stable biomarkers for the diagnosis and progress of LSCC.

Circular RNA: a novel biomarker for progressive laryngeal cancer.

Long noncoding RNA nuclear paraspeckle assembly transcript 1 (NEAT1) plays key role in the progression of some human cancers. However, the role of NEAT1 in human laryngeal squamous cell cancer (LSCC) is still unknown. We therefore investigated the expression and function of NEAT1 in LSCC. NEAT1 level in LSCC and adjacent non-neoplastic tissues were detected by qRT-PCR. NEAT1 was knockdown in LSCC cells and cell proliferation, apoptosis and cell cycle were examined. The growth of xenografts with NEAT1 knockdown LSCC cells was analyzed. NEAT1 level was significantly higher in LSCC than in corresponding adjacent non-neoplastic tissues, and patients with neck nodal metastasis or advanced clinical stage had higher NEAT1 expression. Moreover, siRNA mediated NEAT1 knockdown significantly inhibited the proliferation and induced apoptosis and cell cycle arrest at G1 phase in LSCC cells. The growth of LSCC xenografts was significantly suppressed by the injection of NEAT1 siRNA lentivirus. Furthermore, NEAT1 regulated CDK6 expression in LSCC cells which was mediated by miR-107. NEAT1 plays an oncogenic role in the tumorigenesis of LSCC and may serve as a potential target for therapeutic intervention.

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Long noncoding RNA NEAT1 promotes laryngeal squamous cell cancer through regulating miR-107/CDK6 pathway.

// Tianyi Wu 1, * , Lingmei Qu 2, * , Guoqing He 1, * , Linli Tian 1, * , Liang Li 1 , Han Zhou 1 , Qian Jin 1 , Jingyuan Ren 3 , Yu Wang 1 , Jingting Wang 1 , Xuan Kan 1 , Ming Liu 1 , Jia Shen 4 , Mian Guo 5 , Yanan Sun 1 1 Department of Otorhinolaryngology, Head and Neck Surgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, China 2 Department of Otorhinolaryngology, Head and Neck Surgery, The Fifth Affiliated Hospital of Harbin Medical University, Daqing, China 3 Department of Head and Neck Surgery, The Oncology Hospital of Jilin province, Changchun, China 4 Department of Orthopaedic Surgery and the Orthopaedic Hospital Research Center, University of California, Los Angeles, California, USA 5 Department of Neurosurgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, China * These authors contributed equally to this work Correspondence to: Yanan Sun, e-mail: 76202920@qq.com Mian Guo, e-mail: guomian_hyd@163.com Keywords: laryngeal squamous cell cancer, lncRNA H19, miR-148a-3p, DNMT1 Received: July 07, 2015      Accepted: December 05, 2015      Published: February 08, 2016 ABSTRACT Laryngeal squamous cell carcinoma (LSCC) is a highly aggressive malignant cancer. The regulation of LSCC progression by long non-coding RNA (lncRNA) was not well understood. In this study, we reported that the lncRNA H19 was upregulated in LSCC. The expression levels of H19 were inversely correlated with the survival rate of LSCC patients. Knockdown of H19 expression inhibited LSCC cell migration, invasion and proliferation. We identified microRNA miR-148a-3p as an inhibitory target for H19. Overexpression of miR-148a-3p reduced LSCC migration, invasion and proliferation cell, while inhibition of miR-148a-3p did the opposite. The inhibition of LSCC progression induced by H19 knockdown required the activity of miR-148a-3p. We also identified DNA methyltransferase enzyme DNMT1 as a target of miR-148a-3p. Cellular DNA methylation levels were inhibited by both miR-148a-3p overexpression and H19 knockdown. In summary, our study demonstrated that the lncRNA H19 promoted LSCC progression via miR-148a-3p and DNMT1.

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Yanan Sun

Papers

Long intergenic noncoding RNA HOTAIR is overexpressed and regulates PTEN methylation in laryngeal squamous cell carcinoma.

Combined detection of serum exosomal miR-21 and HOTAIR as diagnostic and prognostic biomarkers for laryngeal squamous cell carcinoma

Circular RNA: a novel biomarker for progressive laryngeal cancer.

Long noncoding RNA NEAT1 promotes laryngeal squamous cell cancer through regulating miR-107/CDK6 pathway.

Regulation of laryngeal squamous cell cancer progression by the lncRNA H19/miR-148a-3p/DNMT1 axis.