BackgroundGastric cancer is the second leading cause of cancer death and remains a major clinical challenge due to poor prognosis and limited treatment options. Long noncoding RNAs (lncRNAs) have emerged recently as major players in tumor biology and may be used for cancer diagnosis, prognosis, and potential therapeutic targets. Although downregulation of lncRNA GAS5 (Growth Arrest-Specific Transcript) in several cancers has been studied, its role in gastric cancer remains unknown. Our studies were designed to investigate the expression, biological role and clinical significance of GAS5 in gastric cancer.MethodsExpression of GAS5 was analyzed in 89 gastric cancer tissues and five gastric cancer cell lines by quantitative reverse-transcription polymerase chain reaction (qRT-PCR). Over-expression and RNA interference (RNAi) approaches were used to investigate the biological functions of GAS5. The effect of GAS5 on proliferation was evaluated by MTT and colony formation assays, and cell apoptosis was evaluated by hochest stainning. Gastric cancer cells transfected with pCDNA3.1 -GAS5 were injected into nude mice to study the effect of GAS5 on tumorigenesis in vivo. Protein levels of GAS5 targets were determined by western blot analysis. Differences between groups were tested for significance using Student’s t-test (two-tailed).ResultsWe found that GAS5 expression was markedly downregulated in gastric cancer tissues, and associated with larger tumor size and advanced pathologic stage. Patients with low GAS5 expression level had poorer disease-free survival (DFS; P = 0.001) and overall survival (OS; P < 0.001) than those with high GAS5 expression. Further multivariable Cox regression analysis suggested that decreased GAS5 was an independent prognostic indicator for this disease (P = 0.006, HR = 0.412; 95%CI = 2.218–0.766). Moreover, ectopic expression of GAS5 was demonstrated to decrease gastric cancer cell proliferation and induce apoptosis in vitro and in vivo, while downregulation of endogenous GAS5 could promote cell proliferation. Finally, we found that GAS5 could influence gastric cancer cells proliferation, partly via regulating E2F1 and P21 expression.ConclusionOur study presents that GAS5 is significantly downregulated in gastric cancer tissues and may represent a new marker of poor prognosis and a potential therapeutic target for gastric cancer intervention.

Long noncoding RNAs (lncRNAs) have emerged recently as major players in governing fundamental biological processes, and many of which are altered in expression and likely to have a functional role in tumorigenesis. Maternally expressed gene 3 (MEG3) is an imprinted gene located at 14q32 that encodes a lncRNA associated with various human cancers. However, its biological role and clinical significance in gastric cancer development and progression are unknown. In this study, to investigate the lncRNA MEG3 expression in gastric cancer, quantitative reverse-transcription polymerase chain reaction was conducted. We found that MEG3 levels were markedly decreased in gastric cancer tissues compared with adjacent normal tissues. Its expression level was significantly correlated with TNM stages, depth of invasion, and tumor size. Moreover, patients with low levels of MEG3 expression had a relatively poor prognosis. Furthermore, knockdown of MEG3 expression by siRNA could promote cell proliferation, while ectopic expression of MEG3 inhibited cell proliferation, promoted cell apoptosis, and modulated p53 expression in gastric cancer cell lines. By 5-aza-CdR treatment, we also observed that MEG3 expression can be modulated by DNA methylation. Our findings present that MEG3 downexpression can be identified as a poor prognostic biomarker in gastric cancer and regulate cell proliferation and apoptosis in vitro.

BackgroundRecent evidence indicates that long noncoding RNAs (lncRNAs) play a critical role in the regulation of cellular processes, such as differentiation, proliferation and metastasis. These lncRNAs are found to be dysregulated in a variety of cancers. BRAF activated non-coding RNA (BANCR) is a 693-bp transcript on chromosome 9 with a potential functional role in melanoma cell migration. The clinical significance of BANCR, and its’ molecular mechanisms controlling cancer cell migration and metastasis are unclear.MethodsExpression of BANCR was analyzed in 113 non-small cell lung cancer (NSCLC) tissues and seven NSCLC cell lines using quantitative polymerase chain reaction (qPCR) assays. Gain and loss of function approaches were used to investigate the biological role of BANCR in NSCLC cells. The effects of BANCR on cell viability were evaluated by MTT and colony formation assays. Apoptosis was evaluated by Hoechst staining and flow cytometry. Nude mice were used to examine the effects of BANCR on tumor cell metastasis in vivo. Protein levels of BANCR targets were determined by western blotting and fluorescent immunohistochemistry.ResultsBANCR expression was significantly decreased in 113 NSCLC tumor tissues compared with normal tissues. Additionally, reduced BANCR expression was associated with larger tumor size, advanced pathological stage, metastasis distance, and shorter overall survival of NSCLC patients. Reduced BANCR expression was found to be an independent prognostic factor for NSCLC. Histone deacetylation was involved in the downregulation of BANCR in NSCLC cells. Ectopic expression of BANCR impaired cell viability and invasion, leading to the inhibition of metastasis in vitro and in vivo. However, knockdown of BANCR expression promoted cell migration and invasion in vitro. Overexpression of BANCR was found to play a key role in epithelial-mesenchymal transition (EMT) through the regulation of E-cadherin, N-cadherin and Vimentin expression.ConclusionWe determined that BANCR actively functions as a regulator of EMT during NSCLC metastasis, suggesting that BANCR could be a biomarker for poor prognosis of NSCLC.

Increasing evidence indicates that long noncoding RNAs (lncRNAs) are involved in diverse biological process. Mouse maternal expressed gene 3 (Meg3) is an imprinted gene and essential for development. Here, we explored the relationship between Meg3 and the function of mouse beta cells in vitro and in vivo. Real-time PCR analyses revealed that Meg3 was more abundantly expressed in Balb/c mouse islets than exocrine glands. Moreover, the expression of Meg3 in islets was decreased in T1DM (NOD female mice) and T2DM (db/db mice) models. Meg3 expression was modulated dynamically by glucose in Min6 cells and isolated mouse islets. The function role of Meg3 was investigated in Min6 cells and normal mouse by knockdown of Meg3 using small interfering RNA. After suppression of Meg3 expression in vitro, insulin synthesis and secretion were impaired and the rate of beta cells apoptosis was increased. Moreover, knockdown of Meg3 in vivo led to the impaired glucose tolerance and decreased insulin secretion, consisted with the reduction of insulin positive cells areas by immunochemistry assays. Notably, islets from Meg3 interference groups showed significant decrease of Pdx-1 and MafA expression in mRNA and protein levels. These results indicate that Meg3 may function as a new regulator of maintaining beta cells identity via affecting insulin production and cell apoptosis. J. Cell. Physiol. 231: 852-862, 2016. © 2015 Wiley Periodicals, Inc.

Background: Increasing evidence indicates that long noncoding RNAs (IncRNAs) perform specific biological functions in diverse processes. Recent studies have reported that IncRNAs may be involved in β cell function. The aim of this study was to characterize the role of IncRNA TUG1 in mouse pancreatic β cell functioning both in vitro and in vivo. Methods: qRT-PCR analyses were performed to detect the expression of lncRNA TUG1 in different tissues. RNAi, MTT, TUNEL and Annexin V-FITC assays and western blot, GSIS, ELISA and immunochemistry analyses were performed to detect the effect of lncRNA TUG1 on cell apoptosis and insulin secretion in vitro and in vivo. Results: lncRNA TUG1 was highly expressed in pancreatic tissue compared with other organ tissues, and expression was dynamically regulated by glucose in Nit-1 cells. Knockdown of lncRNA TUG1 expression resulted in an increased apoptosis ratio and decreased insulin secretion in β cells both in vitro and in vivo . Immunochemistry analyses suggested decreased relative islet area after treatment with lncRNA TUG1 siRNA. Conclusion: Downregulation of lncRNA TUG1 expression affected apoptosis and insulin secretion in pancreatic β cells in vitro and in vivo. lncRNA TUG1 may represent a factor that regulates the function of pancreatic β cells.

The suppressor of zeste-12 protein (SUZ12), a core component of Polycomb repressive complex 2 (PRC2), is implicated in transcriptional silencing by generating di- and tri-methylation of lysine 27 on histone H3 (H3K27Me3). Although SUZ12 is known to be of great importance in several human cancer tumorigenesis, limited data are available on the expression profile and functional role of SUZ12 in non-small cell lung cancer (NSCLC). Here, we determined the expression level of SUZ12 in 40 paired clinical NSCLC tissues and adjacent normal tissues by quantitative reverse-transcription polymerase chain reaction (qRT-PCR). The results showed that SUZ12 was anomalously expressed in NSCLC tissues compared to adjacent noncancerous tissues (P<0.05) and was highly correlated to tumor size, lymph node metastasis, and clinical stages (P<0.05). Additionally, siRNA-mediated knockdown of SUZ12 could inhibit tumor cell growth, migration, and invasion, indicating that SUZ12 might function as an oncogene in NSCLC initiation and progression. Furthermore, we found that SUZ12 silencing significantly reduced the expression levels of transcription factor transcription factor E2F1 (E2F1) as well as potential metastasis promoters Rho-associated, coiled-coil-containing protein kinase 1 (ROCK1) and roundabout homolog 1 (ROBO1) through Western blot analysis. Altogether, we provide evidences suggesting that SUZ12 is an oncogene in NSCLC and can regulate NSCLC cells proliferation and metastasis partly via reducing E2F1, ROCK1, and ROBO1. Thus, SUZ12 may represent a new potential diagnostic marker for NSCLC and may be a novel therapeutic target for NSCLC intervention.

Background: Evidence shows that long non-coding RNAs (lncRNAs) are involved in individual development, cell differentiation, cell cycle processes and other important life processes and are closely related to major human diseases, including diabetes. Recent studies have reported that lncRNAs are involved in β cell functions and that lncRNA Gas5 levels decreased in T2DM patients’ serum. The purpose of this study was to clarify the role of lncRNA Gas5 in mouse β cell functions in vitro and in vivo. Methods: lncRNA Gas5 expression in T2DM and normal mouse tissues was analyzed using qRT-PCR. RNAi, qRT-PCR, Annexin V-FITC assays, western blot, GSIS and RIA were performed to detect the effects of lncRNA Gas5 on insulin synthesis and secretion in vitro and in vivo. Results: The lncRNA Gas5 level was significantly decreased in db/db mice. However, lncRNA Gas5 expression was relatively high in the pancreas of normal mice. Knockdown of lncRNA Gas5 expression led to cell cycle G1 arrest and impaired insulin synthesis and secretion in Min6 cells. Further, knockdown of lncRNA Gas5 expression in primary isolated islets resulted in decreased expression of insulin gene and transcription factors, Pdx1 and MafA. These results indicate that lncRNA Gas5 might perform as a new regulator, maintaining β cell identity and function by affecting insulin synthesis and secretion.

SUZ12 is a core component of the polycomb repressive complex 2 (PRC2), which could silence gene transcription by generating trimethylation on lysine 27 residue of histone H3 (H3K27Me3). Meanwhile, SUZ12 has been found to be overexpressed in multiple cancers; however, the clinical significance and molecular mechanisms of SUZ12 controlling gastric cancer cell proliferation and metastasis are unclear. In this study, we found that SUZ12 expression was significantly increased in 64 gastric tumor tissues compared with normal tissues. Additionally, SUZ12 expression was associated with pathological stage, metastasis distance, and shorter overall survival of gastric cancer patients. Knockdown of SUZ12 expression impaired cell proliferation and invasion in vitro, leading to the inhibition of metastasis in vivo. Upregulation of SUZ12 was found to play a key role in gastric cancer cell proliferation and metastasis through the regulation of EMT and KLF2 expression.