Identification of the long non‑coding RNA LET as a novel tumor suppressor in gastric cancer

Role of lncRNAs in the Development of an Aggressive Phenotype in Gallbladder Cancer

Long non-coding RNAs are sequences longer than 200 nucleotides that are involved in different normal and abnormal biological processes exerting their effect on proliferation and differentiation, among other cell features. Functionally, lncRNAs can regulate gene expression within the cells by acting at transcriptional, post-transcriptional, translational, or post-translational levels. However, in pathological conditions such as cancer, the expression of these molecules is deregulated, becoming elements that can help in the acquisition of tumoral characteristics in the cells that trigger carcinogenesis and cancer progression. Specifically, in gallbladder cancer (GBC), recent publications have shown that lncRNAs participate in the acquisition of an aggressive phenotype in cancer cells, allowing them to acquire increased malignant capacities such as chemotherapy resistance or metastasis, inducing a worse survival in these patients. Furthermore, lncRNAs are useful as prognostic and diagnostic biomarkers since they have been shown to be differentially expressed in tumor tissues and serum of individuals with GBC. Therefore, this review will address different lncRNAs that could be promoting malignant phenotypic characteristics in GBC cells and lncRNAs that may be useful as markers due to their capability to predict a poor prognosis in GBC patients.

Role of the long non-coding RNA LINC00052 in tumors

Long intergenic non-protein coding RNA 52 (LINC00052) is a non-coding RNA with >200 nucleotides in length, which exerts important effects on several physiological and pathological processes of the human body. Recent studies have demonstrated that LINC00052 plays key roles in the tumorigenesis, progression and metastasis of multiple types of human cancer, including hepatocellular carcinoma, breast cancer, colorectal cancer, cervical carcinoma and gastric cancer. However, the associations between LINC00052 and these tumors remain unclear. The present review summarizes the biological functions of LINC00052 during the pathogenic process of certain tumors, and discusses its potential therapeutic targets.

Long Noncoding RNAs in Gastrointestinal Cancer: Tumor Suppression Versus Tumor Promotion

Approximately 80% of the human genome harbors biochemical marks of active transcription that its majority transcribes to noncoding RNAs, namely long noncoding RNAs (lncRNAs). LncRNAs are heterogeneous RNA transcripts that regulate critical biological processes such as cell survival and death. They involve in the progression of different cancers by affecting transcriptional and post-transcriptional modifications as well as epigenetic control of numerous tumor suppressors and oncogenes. Recent findings show that aberrant expression of lncRNAs is associated with tumor initiation, progression, invasion, and overall survival of patients with gastrointestinal (GI) cancers. Some lncRNAs play as tumor suppressors in all GI cancers, but others play as tumor promoters. However, some other lncRNAs might function as a tumor suppressor in one GI cancer, but as a tumor promoter in another GI cancer type. This fact highlights possible context dependency of the expression patterns and roles of at least some lncRNAs in GI cancer development and progression. Here, we review the functional relation of lncRNAs involved in the development and progression of GI cancer by focusing on their roles as tumor suppressor and tumor promoter genes.

Long non-coding RNA signature in gastric cancer

Gastric cancer as a common human malignancy has been associated with aberrant expressions of several coding and non-coding genes. Long non-coding RNAs (lncRNAs) as regulators of gene expressions at different genomic, transcriptomic and post-transcriptomic levels are among putative biomarkers and therapeutic targets in gastric cancer. In the present study, we have searched available literature and listed lncRNAs that are involved in the pathogenesis of gastric cancer. In addition, we discuss associations between expressions of these lncRNAs and tumoral features or risk factors for gastric cancer. Based on the established role of lncRNAs in regulation of genomic stability, cell cycle, apoptosis, angiogenesis and other aspects of cell physiology, the potential of these transcripts as therapeutic targets in gastric cancer should be evaluated in future studies.

LncRNA GMDS-AS1 inhibits lung adenocarcinoma development by regulating miR-96-5p/CYLD signaling

According to the global cancer statistic, lung cancer is one of the most dangerous tumors, which poses a serious threat to human health. Exploration the mechanism of lung cancer and new targeted therapeutic measures is always the hot topic. Long noncoding RNA (lncRNA) is an important factor affecting the development of tumors. However, the research on the mechanism of lncRNA in the progress of lung cancer needs to be further expanded. In this study, we found that the expression of lncRNA GMDS-AS1 was significantly reduced in lung adenocarcinoma (LUAD) tissues and cells. Upregulated GMDS-AS1 can significantly inhibit the proliferation of LUAD cells and promote cell apoptosis in vitro and in vivo. The results indicate that GMDS-AS1 acts as a tumor suppressor gene to affect the development of LUAD. Further studies revealed that GMDS-AS1 is a target gene of miR-96-5p, and GMDS-AS1 regulates proliferation and apoptosis of LUAD cells in association with miR-96-5p. In addition, we also confirmed that CYLD lysine 63 deubiquitinase (CYLD) is also a target gene of miR-96-5p. Through various validations, we confirmed that GMDS-AS1 can act as a ceRNA to upregulate the expression of CYLD by sponging miR-96-5p. Moreover, the intervention of GMDS-AS1/miR-96-5p/CYLD network can regulate the proliferation and apoptosis of LUAD cells. In this study, we revealed that the GMDS-AS1/miR-96-5p/CYLD network based on ceRNA mechanism plays an important role in the development of LUAD and provides a new direction and theoretical basis for targeted therapy of LUAD.

Long non-coding RNAs in non-small cell lung cancer: functions and distinctions from other malignancies

Lung cancer leads to the most cancer-related death in the world. It was shown from the increasing evidences that long non-coding RNAs (lncRNAs) are emerging as molecules for diagnosis, prognosis and even therapy of lung cancer and other malignancies. The biological functions or involved signaling pathways of lncRNAs are always found to be inconsistent among different types of malignancies. However, no available literature has systemically summarized differences in the functions and underlying molecular mechanisms of lncRNAs between lung cancer and other cancers. In this review, the biological functions and molecular mechanisms of lncRNAs in lung cancer were introduced. Furthermore, their functional differences between lung cancer and other malignancies were discussed. Finally, their potential clinical applications in future lung cancer therapy were focused on.

LncRNA-LET relieves hypoxia-induced injury in H9c2 cells through regulation of miR-138

Ischemic heart disease (IHD) is a common cardiovascular disease, occurs when coronary artery blood circularity cannot match with the heart's need. The present work attempted to study the effects of long noncoding RNA (lncRNA) low expression in tumor (LET) on the progression of IHD. H9c2 cells were injured by hypoxia to mimic a cell model of IHD. The effects of lncRNA-LET on hypoxia-injured H9c2 cells were tested by using cell counting kit-8 assay, flow cytometry, and Western blot analysis. MicroRNA-138 (miR-138) expression was tested by a quantitative real-time polymerase chain reaction, and the expression of c-Jun N-terminal kinase (JNK) and p38MAPK (p38-mitogen-activated protein kinase) proteins was measured by Western blot analysis. We found that hypoxia exposure significantly repressed the viability of H9c2 cells, and induced apoptosis. Meanwhile, phosphorylation of JNK and p38MAPK was enhanced by hypoxia. The expression of lncRNA-LET was repressed by hypoxia. Overexpression of lncRNA-LET attenuated hypoxia-induced injury in H9c2 cells. Moreover, miR-138 was a downstream effector of lncRNA-LET, that miR-138 was highly expressed in lncRNA-LET-overexpressed cell. The cardioprotective effects of lncRNA-LET were abolished when miR-138 was silenced. In conclusion, this study revealed the cardioprotective function of lncRNA-LET. lncRNA-LET conferred its cardioprotective effects possibly via upregulation of miR-138 and thus repressing the JNK and p38MAPK pathways.

A Prognostic 5-lncRNA Expression Signature for Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a common malignant cancer that accounts for 5-10% of all cancers. This study aimed to identify essential genes associated with the prognosis of HNSCC and construct a powerful prognostic model for the risk assessment of HNSCC. RNAseq expression profile data for the patients with HNSCC were obtained from the TCGA database (GEO). A total of 500 samples with full clinical following-up were randomly divided into a training set and a validation set. The training set was used to screen for differentially expressed lncRNAs. Single-factor survival analysis was performed to obtain lncRNAs that associated with prognosis. A robust likelihood-based survival model was constructed to identify the lncRNAs that are essential for the prognosis of HNSCC. A co-expression network between genes and lncRNAs was also constructed to identify lncRNAs co-expressed with genes to serve as the final signature lncRNAs for prognosis. Finally, the prognostic effect of the signature lncRNAs was tested by multi-factor survival analysis and a scoring model for the prognosis of HNSCC was constructed. Moreover, the results of the validation set and the relative expression levels of the signature lncRNAs in the tumour and the adjacent tissue were consistent with the results of the training set. The 5 lncRNAs were distributed among 3 expression modules. Further KEGG pathway enrichment analysis showed that these 3 co-expressed modules participate in different pathways, and many of these pathways are associated with the development and progression of disease. Therefore, we proposed that the 5 validated lncRNAs can be used to predict the prognosis of HNSCC patients and can be applied in postoperative treatment and follow-up.

LncRNA GACAT1 Promotes Gastric Cancer Cell Growth, Invasion And Migration By Regulating MiR-149-mediated Of ZBTB2 And SP1

Long non-coding RNAs (lncRNAs) were involved in the progression of gastric cancer (GC). In our study, we have determined that GACAT1 expression was upregulated in GC. Overexpression of GACAT1 promoted GC cell proliferation, invasion and migration. We also determined that miR-149 directly interacts with the target site on GACAT1. Furthermore, we investigated that miR-149 downregulated ZBTB2 and SP1 expressions which were induced by GACAT1, miR-149 inhibited GC cell growth and invasion mediated by GACAT1. In conclusion, we found that miR-149 downregulated ZBTB2 and SP1 expressions, and inhibited GC cell progression mediated by GACAT1. Therefore, we indicated that GACAT1 and miR-149 may be potential therapeutic targets for GC.

Long non-coding RNA-ENST00000434223 suppresses tumor progression in gastric cancer cells through the Wnt/β-catenin signaling pathway

BACKGROUND

Gastric cancer (GC) develops from the lining of the stomach. The present study aimed to explore the effects of long non-coding RNA-ENST00000434223 (lncRNA ENST00000434223) on gastric cancer (GC) cells.

METHODS

One hundred and four GC tissues and paracancerous tissues were collected from GC patients, and expression of ENST00000434223, Wnt2b, β-catenin, cyclinD1, E-cadherin, N-cadherin, vimentin, and snail was subsequently assessed. Morphological changes in cells were assessed using an inverted microscope, and expression of Bcl-2, Bax and caspase-3 was examined.

RESULTS

We found that expression of Wnt2b, β-catenin, cyclinD1, N-cadherin, vimentin, and snail was increased in GC tissues, while expression of ENST00000434223 and E-cadherin was decreased. SGC-7901 cells were closely arranged, and expression of Wnt2b, β-catenin, CyclinD1, N-cadherin, Vimentin, snail and Bcl-2 was increased, whereas expression of ENST00000434223, E-cadherin, Bax and caspase-3 was decreased. Furthermore, the rate of apoptosis was decreased and cell proliferation, invasion and migration were increased in response to downregulation of ENST00000434223. By contrast, upregulation of ENST00000434223 exhibited the opposite effects in MKN-45 cells.

CONCLUSION

The results of this study provide a promising experimental basis for the treatment of gastric cancer through interventional targeting of lncRNA ENST00000434223.

Long non-coding RNAs: crucial regulators of gastrointestinal cancer cell proliferation

Studies of long non-coding RNAs (lncRNAs) have been prevalent in the field of non-coding RNA regulation in recent years. LncRNAs exert crucial effects on malignant cell processes in the gastrointestinal system, including proliferation. Aberrant lncRNA expression, through both oncogenes and tumor suppressor genes, is instrumental to tumor cell proliferation. Here, we summarize the different molecular mechanisms and relevant signaling pathways through which multifarious lncRNAs regulate cell proliferation and we show that lncRNAs are potential biomarkers for gastrointestinal cancers.

Molecular Crosstalking among Noncoding RNAs: A New Network Layer of Genome Regulation in Cancer

Over the past few years, noncoding RNAs (ncRNAs) have been extensively studied because of the significant biological roles that they play in regulation of cellular mechanisms. ncRNAs are associated to higher eukaryotes complexity; accordingly, their dysfunction results in pathological phenotypes, including cancer. To date, most research efforts have been mainly focused on how ncRNAs could modulate the expression of protein-coding genes in pathological phenotypes. However, recent evidence has shown the existence of an unexpected interplay among ncRNAs that strongly influences cancer development and progression. ncRNAs can interact with and regulate each other through various molecular mechanisms generating a complex network including different species of RNAs (e.g., mRNAs, miRNAs, lncRNAs, and circRNAs). Such a hidden network of RNA-RNA competitive interactions pervades and modulates the physiological functioning of canonical protein-coding pathways involved in proliferation, differentiation, and metastasis in cancer. Moreover, the pivotal role of ncRNAs as keystones of network structural integrity makes them very attractive and promising targets for innovative RNA-based therapeutics. In this review we will discuss: (1) the current knowledge on complex crosstalk among ncRNAs, with a special focus on cancer; and (2) the main issues and criticisms concerning ncRNAs targeting in therapeutics.

LINC00052 upregulates EPB41L3 to inhibit migration and invasion of hepatocellular carcinoma by binding miR-452-5p

Numerous studies have demonstrated that a class of long noncoding RNAs (lncRNAs) are dysregulated in hepatocellular carcinoma (HCC) and they are closely related with tumorigenesis. Our previous studies indicated that LINC00052 was a downregulated lncRNA in HCC and acted as a tumor suppressor gene. Using transcription microarray analysis, we found that knockdown of LINC00052 resulted in EPB41L3 downregulation. However, the function of EPB41L3 and the mechanism of LINC00052 downregulating EPB41L3 in HCC remain unclear. In this study, we found that overexpression of LINC00052 could upregulate the EPB41L3 expression and it might serve as a tumor suppressor gene in HCC. Database analysis showed that miR-452-5P could target LINC00052. The binding regions between LINC00052 and miR-452-5P were confirmed by luciferase assays. Moreover, LINC00052 inhibited cell malignant behavior by increasing miR-452-5P expression, suggesting that LINC00052 was negatively regulated by miR-452-5P. In addition, overexpression of miR-452-5P resulted in a decrease of EPB41L3 expression, suggesting that EPB41L3 was as a target of miR-452-5P. In conclusion, these results demonstrated that a novel pathway was mediated by LINC00052 in HCC.

LINC00052 Promotes Gastric Cancer Cell Proliferation and Metastasis via Activating the Wnt/β-Catenin Signaling Pathway

Gastric cancer (GC) is one of the most common malignant tumors of the digestive system. The etiology of GC is complex, and much more attention should be paid to genetic factors. In this study, we explored the role and function of LINC00052 in GC. We applied qRT-PCR and Northern blot to detect the expression of LINC00052 and found it was highly expressed during GC. We also investigated the effects of LINC00052 on tumor prognosis and progression and found that LINC00052 indicated poor prognosis and tumor progression. By performing MTT, colony formation, and Transwell assays, we found that LINC00052 promoted MGC-803 cell proliferation and metastasis. Pull-down and RIP assays showed that LINC00052 could interact with β-catenin and methyltransferase SMYD2, and immunoprecipitation detection showed that LINC00052 promoted β-catenin methylation to maintain its stability, so as to activate the Wnt/β-catenin pathway. Furthermore, XAV939 (inhibitor of β-catenin) was used to treat MGC-803 cells, and we found that LINC00052 promoted proliferation and metastasis, possibly by activation of the Wnt/β-catenin pathway. In conclusion, our research demonstrated a carcinogenic role for LINC000052 in GC, which may represent a new approach for the prevention and therapy of this cancer.