Background: Long non-coding RNAs play an important role in tumorigenesis, hence, identification of cancer-associated lncRNAs and investigation of their biological functions and molecular mechanisms are important for understanding the development and progression of cancer. Recently, the downregulation of lncRNA MEG3 has been observed in various human cancers. However, its role in non-small cell lung cancer (NSCLC) is unknown. The aim of this study was to examine the expression pattern of MEG3 in NSCLC and to evaluate its biological role and clinical significance in tumor progression. Methods: Expression of MEG3 was analyzed in 44 NSCLC tissues and 7 NSCLC cell lines by qRT-PCR. Over-expression approaches were used to investigate the biological functions of MEG3 in NSCLC cells. Bisulfite sequencing was used to investigate DNA methylation on MEG3 expression. The effect of MEG3 on proliferation was evaluated by MTT and colony formation assays, and cell apoptosis was evaluated by Hoechst staining and Flow-cytometric analysis. NSCLC cells transfected with pCDNA-MEG3 were injection into nude mice to study the effect of MEG3 on tumorigenesis in vivo . Protein levels of MEG3 targets were determined by western blot analysis. Differences between groups were tested for significance using Student’s t-test (two-tailed). Results: MEG3 expression was decreased in non-small cell lung cancer (NSCLC) tumor tissues compared with normal tissues, and associated with advanced pathologic stage, and tumor size. Moreover, patients with lower levels of MEG3 expression had a relatively poor prognosis. Overexpression of MEG3 decreased NSCLC cells proliferation and induced apoptosis in vitro and impeded tumorigenesis in vivo. MDM2 and p53 protein levels were affected by MEG3 over-expression in vitro. Conclusions: Our findings indicate that MEG3 is significantly down-regulated in NSCLC tissues that could be affected by DNA methylation, and regulates NSCLC cell proliferation and apoptosis, partially via the activition of p53. Thus, MEG3 may represent a new marker of poor prognosis and is a potential therapeutic target for NSCLC intervention.

Long noncoding RNAs (lncRNAs) have emerged as critical regulators in a variety of human cancers, including gastric cancer (GC). However, the function and mechanisms responsible for these molecules in GC are not fully understood. In our previous study, we found that GC associated lncRNA HOXA11-AS is significantly upregulated in GC tissues. Over-expressed HOXA11-AS promotes GC cells proliferation and invasion through scaffolding the chromatin modification factors PRC2, LSD1 and DNMT1. HOXA11-AS expression levels in GC cells was detected by quantitative real-time PCR (qPCR). HOXA11-AS siRNAs and overexpression vector were transfected into GC cells to down-regulate or up-regulate HOXA11-AS expression. In vitro and in vivo assays were performed to investigate the functional role of HOXA11-AS in GC cells cell cycle progression, invasion and metastasis. RIP and ChIP assays were used to determine the mechanism of HOXA11-AS’s regulation of underlying targets. We found that knockdown of HOXA11-AS induced GC cells G0/G1 phase arrest and suppressed GC cells migration, invasion and metastasis in vivo. Moreover, mechanistic investigation showed that HOXA11-AS could interact with WDR5 and promote β-catenin transcription, bind with EZH2 and repress P21 transcription, and induce KLF2 mRNA degradation via interacting with STAU1. Taken together, these findings show that HOXA11-AS not only could promote GC cells migration and invasion in vitro, but also promotes GC cells metastasis in vivo, at least in part, by regulating β-catenin and KLF2.

Exosomes are nano-sized membrane-bound vesicles and contain active substances (DNA, noncoding RNA [ncRNA], protein), which provide a novel method of transferring effector messages between cells. Circular RNAs (circRNAs), a kind of ncRNA, have attracted increasing attention over the last decade given advances in whole-genome and transcriptome sequencing technologies. It has become increasingly clear that circRNAs regulate gene expression through various actions and play diverse roles in many fields of human cancer biology. Notably, several studies reported that circRNAs are enriched in exosomes and that exosomal circRNAs play an important role in cancer biology. Exosomal circRNAs can be taken up by neighboring or distant cells and affect many aspects of physiological and pathological conditions of the recipient cells, potentially promoting cell communication and tumor metastasis. Herein, we briefly review the molecular mechanisms of circRNAs and recent findings regarding exosomal circRNAs, and highlight the specific roles of exosomal circRNAs in human cancer.

NSCLC (non-small-cell lung cancer) is the leading cause of cancer-related mortality worldwide. Both epigenetic and genetic changes contribute to the initiation, development and metastasis of NSCLC. Recently, accumulating data have begun to support the notion that long noncoding RNAs (lncRNAs) function as new crucial regulators of diverse biological processes, including proliferation, apoptosis and metastasis, and play crucial roles in tumorigenesis. Nevertheless, further study is warranted to comprehensively determine lncRNAs' functions and potential mechanism. In this study, we performed a comprehensive analysis of the lncRNA expression profile of NSCLC using data from TCGA and Gene Expression Omnibus (GEO). PCAT6 expression level in a cohort of 60 pairs of NSCLC tissues using quantitative real-time PCR (qRT-PCR). Additionally, Loss-of-function assays and gain-of-function assays were used to assess the role of PCAT6 in promoting NSCLC progression. Tumor formation assay in a nude mouse model was performed to verity the role of PCAT6 in NSCLC in vivo. Meanwhile, RIP, ChIP, resue experiment and western blot assays were used to highlights the potential molecular mechanism of PCAT6 in NSCLC. We identified that an oncogene, PCAT6, was upregulated in NSCLC, and this upregulation was verified in a cohort of 60 pairs of NSCLC tissues. Additionally, the expression level of PCAT6 was correlated with tumor size (P = .036), lymph node metastasis (P = .029) and TNM stage (P = .038). Loss-of-function and gain-of-function assays were used to assess the role of PCAT6 in promoting NSCLC progression. The results revealed that PCAT6 knockdown mitigated NSCLC cell growth by inducing G1-phase cell cycle arrest and apoptosis in vitro and in vivo. Whereas, PCAT6 overexpression could promoted tumor cell growth. Meanwhile, PCAT6 additionally promoted NSCLC cell migration and invasion. Furthermore, mechanistic investigation demonstrated that the oncogenic activity of PCAT6 is partially attributable to its repression of LATS2 via association with the epigenetic repressor EZH2 (Enhancer of zeste homolog 2). Overall, our study highlights the essential role of PCAT6 in NSCLC, suggesting that PCAT6 might be a potent therapeutic target for patients with NSCLC.

Long non-coding RNA LINC01133 represses KLF2, P21 and E-cadherin transcription through binding with EZH2, LSD1 in non small cell lung cancer

The THO complex (THOC) is ubiquitously involved in RNA modification and various THOC proteins have been reported to regulate tumor development. However, the role of THOC3 in lung cancer remains unknown. In this study, we identified that THOC3 was highly expressed in lung squamous cell carcinoma (LUSC) and negatively associated with prognosis. THOC3 knockdown inhibited LUSC cell growth, migration, and glycolysis. THOC3 expression was regulated by TRiC proteins, such as CCT8 and CCT6A, which supported protein folding. Furthermore, THOC3 could form a complex with YBX1 to promote PFKFB4 transcription. THOC3 was responsible for exporting PFKFB4 mRNA to the cytoplasm, while YBX1 ensured the stability of PFKFB4 mRNA by recognizing m5C sites in its 3′UTR. Downregulation of PFKFB4 suppressed the biological activities of LUSC. Collectively, these findings suggest that THOC3, folded by CCT proteins can collaborate with YBX1 to maintain PFKFB4 expression and facilitate LUSC development. Therefore, THOC3 could be considered as a novel promising therapeutic target for LUSC.