Downregulation of lncRNA TUG1 affects apoptosis and insulin secretion in mouse pancreatic ß cells.

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 ß cell function. The aim of this study was to characterize the role of IncRNA TUG1 in mouse pancreatic ß 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 ß 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 ß cells in vitro and in vivo. lncRNA TUG1 may represent a factor that regulates the function of pancreatic ß cells.

SUZ12 promotes gastric cancer cell proliferation and metastasis by regulating KLF2 and E-cadherin.

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.

Downregulation of BRAF activated non-coding RNA is associated with poor prognosis for non-small cell lung cancer and promotes metastasis by affecting epithelial-mesenchymal transition.

BACKGROUND: Recent 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. METHODS: Expression 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. RESULTS: BANCR 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. CONCLUSION: We 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.

Decreased expression of long noncoding RNA GAS5 indicates a poor prognosis and promotes cell proliferation in gastric cancer.

BACKGROUND: Gastric 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. METHODS: Expression 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). RESULTS: We 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. CONCLUSION: Our 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.