LincHOTAIR epigenetically silences miR34a by binding to PRC2 to promote the epithelial-to-mesenchymal transition in human gastric cancer.

lncRNAs play important roles in the epigenetic regulation of carcinogenesis and progression. Previous studies suggest that HOTAIR contributes to gastric cancer (GC) development, and the overexpression of HOTAIR predicts a poor prognosis. In this study, we found that HOTAIR was more highly expressed in diffuse-type GC than in intestinal type (P=0.048). In the diffuse type, there is significant relationship between HOTAIR expression and DFS (P<0.001). CDH1 was downregulated in diffuse-type GC tissues (P=0.0007) and showed a negative relationship with HOTAIR (r(2)=0.154, P=0.0354). In addition, HOTAIR knockdown significantly repressed migration, invasion and metastasis both in vitro and vivo and reversed the epithelial-to-mesenchymal transition in GC cells. We also showed that HOTAIR recruiting and binding to PRC2 epigenetically represses miR34a, which controls the targets C-Met (HGF/C-Met/Snail pathway) and Snail, thus contributing to GC cell-EMT process and accelerating tumor metastasis. Moreover, it is demonstrated that HOTAIR crosstalk with microRNAs during epigenetic regulation. Our results suggest that HOTAIR acts as an EMT regulator and may be a candidate prognostic biomarker and a target for new therapies in GC patients.

Low expression of long noncoding RNA PANDAR predicts a poor prognosis of non-small cell lung cancer and affects cell apoptosis by regulating Bcl-2.

Recently, a novel class of transcripts, long noncoding RNAs (lncRNAs), is involved in diseases including cancer. Here, we investigated the the role of lncRNA PANDAR in the progression of non-small cell lung carcinoma (NSCLC). PANDAR, interacting with NF-YA, was generally downregulated in NSCLC tissues. In a cohort of 140 NSCLC patients, decreased PANDAR expression was negatively correlated with greater tumor size (P<0.001) and advanced TNM stage (P=0.002). Moreover, PANDAR could serve as an independent predictor for overall survival in NSCLC (P=0.015). Further experiments demonstrated that PANDAR expression was induced by p53, and chromatin immunoprecipitation (ChIP) assays confirmed that PANDAR was a direct transcriptional target of p53 in NSCLC cells. PANDAR overexpression significantly repressed the proliferation in vitro and in vivo. We also showed that PANDAR-mediated growth regulation is in part due to the transcriptional modulation of Bcl-2 by interacting with NF-YA, thus affecting NSCLC cell apoptosis. To our knowledge, this is the first report which showed the role of PANDAR in the progression of NSCLC. The p53/PANDAR/NF-YA/Bcl-2 interaction might serve as targets for NSCLC diagnosis and therapy.

EZH2-mediated epigenetic suppression of long noncoding RNA SPRY4-IT1 promotes NSCLC cell proliferation and metastasis by affecting the epithelial-mesenchymal transition.

Recent evidence indicates that long noncoding RNAs (lncRNAs) have a critical role in the regulation of cellular processes such as differentiation, proliferation, and metastasis. These lncRNAs are dysregulated in a variety of cancers and many function as tumor suppressors; however, the regulatory factors involved in silencing lncRNA transcription are poorly understood. In this study, we showed that epigenetic silencing of lncRNA SPRY4 intronic transcript 1 (SPRY4-IT1) occurs in non-small-cell lung cancer (NSCLC) cells through direct transcriptional repression mediated by the Polycomb group protein enhancer of zeste homolog 2 (EZH2). SPRY4-IT1 is derived from an intron within SPRY4, and is upregulated in melanoma cells; knockdown of its expression leads to cell growth arrest, invasion inhibition, and elevated rates of apoptosis. Upon depletion of EZH2 by RNA interference, SPRY4-IT1 expression was restored, and transfection of SPRY4-IT1 into NSCLC cells resulted in a significant antitumoral effect, both in culture and in xenografted nude mice. Moreover, overexpression of SPRY4-IT1 was found to have a key role in the epithelial-mesenchymal transition through the regulation of E-cadherin and vimentin expression. In EZH2-knockdown cells, which characteristically showed impaired cell proliferation and metastasis, the induction of SPRY4-IT1 depletion partially rescued the oncogenic phenotype, suggesting that SPRY4-IT1 repression has an important role in EZH2 oncogenesis. Of most relevance, translation of these findings into human NSCLC tissue samples demonstrated that patients with low levels of SPRY4-IT1 expression had a shorter overall survival time, suggesting that SPRY4-IT1 could be a biomarker for poor prognosis of NSCLC.

P53-regulated long non-coding RNA TUG1 affects cell proliferation in human non-small cell lung cancer, partly through epigenetically regulating HOXB7 expression.

Recently, a novel class of transcripts, long non-coding RNAs (lncRNAs), is being identified at a rapid pace. These RNAs have critical roles in diverse biological processes, including tumorigenesis. Here we report that taurine-upregulated gene 1 (TUG1), a 7.1-kb lncRNA, recruiting and binding to polycomb repressive complex 2 (PRC2), is generally downregulated in non-small cell lung carcinoma (NSCLC) tissues. In a cohort of 192 NSCLC patients, the lower expression of TUG1 was associated with a higher TNM stage and tumor size, as well as poorer overall survival (P<0.001). Univariate and multivariate analyses revealed that TUG1 expression serves as an independent predictor for overall survival (P<0.001). Further experiments revealed that TUG1 expression was induced by p53, and luciferase and chromatin immunoprecipitation (ChIP) assays confirmed that TUG1 was a direct transcriptional target of p53. TUG1 knockdown significantly promoted the proliferation in vitro and in vivo. Moreover, the lncRNA-mediated regulation of the expression of HOX genes in tumorigenesis and development has been recently receiving increased attention. Interestingly, inhibition of TUG1 could upregulate homeobox B7 (HOXB7) expression; ChIP assays demonstrated that the promoter of HOXB7 locus was bound by EZH2 (enhancer of zeste homolog 2), a key component of PRC2, and was H3K27 trimethylated. This TUG1-mediated growth regulation is in part due to specific modulation of HOXB7, thus participating in AKT and MAPK pathways. Together, these results suggest that p53-regulated TUG1 is a growth regulator, which acts in part through control of HOXB7. The p53/TUG1/PRC2/HOXB7 interaction might serve as targets for NSCLC diagnosis and therapy.