Negative regulation of lncRNA GAS5 by miR-196a inhibits esophageal squamous cell carcinoma growth

Dysregulation of GAS5-miRNA-Mediated Signaling Pathways in Cancer Pathobiology: A Comprehensive Exploration of Pathways Influenced by this Axis

The long non-coding RNA Growth Arrest-Specific 5 (GAS5) is pivotal in modulating key signaling pathways by functioning as a molecular sponge for microRNAs (miRNAs). GAS5 is notably recognized for its antitumor properties, primarily through its ability to sequester oncogenic miRNAs, thereby influencing critical pathways such as p53, Wnt/β-catenin, and PI3K/Akt, all of which are integral to cell proliferation, apoptosis, and metastasis. The disruption of GAS5-miRNA interactions has been implicated in various malignancies, reinforcing its potential as both a biomarker and a therapeutic target. This paper delves into the intricate signaling cascades affected by GAS5-miRNA interactions and thoroughly investigates the diagnosis and treatment prospects associated with GAS5. Moreover, it addresses both the challenges and opportunities for translational applicability of these findings in clinical environments. The study emphasizes GAS5's significance within the cancer molecular landscape and posits that precise modulation of GAS5-miRNA interactions could catalyze transformative developments in cancer diagnostics and therapeutic approaches. This comprehensive review not only highlights the critical role of non-coding RNAs in cancer biology but also aims to lay the groundwork for future investigations aimed at harnessing these insights for therapeutic interventions.

Role of exercise on the reduction of cancer development: a mechanistic review from the lncRNA point of view

More research has been done on the correlation between exercise and cancer, which has revealed several ways that physical activity decreases the risk of developing the disease. The developing function of lncRNAs as an important molecular link between exercise and cancer suppression is the main topic of this review. According to recent research, regular physical exercise also alters the expression levels of several lncRNAs, which are generally elevated in cancer. A complex network of interactions that may provide protective effects against carcinogenesis is suggested by the contribution of these lncRNAs in various cellular processes, such as epigenetic alterations, proliferation, and apoptosis regulation. We offer a comprehensive summary of the existing information regarding specific lncRNAs that are influenced by physical activity and could potentially impact cancer-related processes. We also go over the difficulties in interpreting these alterations, taking into account the fact that several lncRNAs have a dual function in promoting and preventing cancer in various physiological settings. To understand the complex impacts of exercise-induced lncRNA regulation in cancer biology, more study is required. The critique strongly highlights the possibility of lncRNAs serving as both indicators and treatment prospects for cancer-preventive strategies.

Epigenetic Regulation by lncRNA GAS5/miRNA/mRNA Network in Human Diseases

The interplay between long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) is crucial in the epigenetic regulation of mRNA and protein expression, impacting the development and progression of a plethora of human diseases, such as cancer, cardiovascular disease, inflammatory-associated diseases, and viral infection. Among the many lncRNAs, growth arrest-specific 5 (GAS5) has garnered substantial attention for its evident role in the regulation of significant biological processes such as proliferation, differentiation, senescence, and apoptosis. Through miRNA-mediated signaling pathways, GAS5 modulates disease progression in a cell-type-specific manner, typically by influencing proteins involved in inflammation and cell death. While GAS5 is recognized as a tumor suppressor in cancer, recent reports highlight its broader regulatory capacity in non-cancerous diseases. Its modulation of protein expression through the GAS5/miRNA network has been shown to both mitigate and exacerbate disease, depending on the specific context. Furthermore, the therapeutic potential of GAS5 manipulation, via knockdown or overexpression, offers promising avenues for targeted interventions across human diseases. This review explores the dualistic impacts of the GAS5/miRNA network in conditions such as cancer, cardiovascular disease, viral infections, and inflammatory disorders. Through the evaluation of current evidence, we aim to provide insight into GAS5's biological functions and its implications for future research and therapeutic development.

Abnormal activation of genomic LINE1 elements caused by DNA demethylation contributes to lncRNA CASC9 overexpression in esophageal squamous cell carcinoma

Long noncoding RNA (lncRNA) cancer susceptibility 9 (CASC9) has been found to be overexpressed and functions as an oncogene in many cancer types. We investigated the molecular mechanism underlying CASC9 overexpression in esophageal squamous cell carcinoma (ESCC). Transcripts containing exons 2 and 6 and exons 4 and 6 showed the highest CASC9 expression levels in ESCC, no transcripts were detected in the normal esophageal epithelial Het1A cell line. The Long Interspersed Nuclear Element-1 (LINE1 or L1) element in the genome was found to participate in the evolution of lncRNA CASC9, the antisense promoter (ASP) of L1 provides the cis-regulatory elements necessary for CASC9 activation, and the antisense chain of L1 participates in the formation of exons of CASC9. The activation of the antisense promoter was due to the aberrant hypomethylation of L1 elements. An active enhancer element was identified in the downstream region of CASC9 gene by ChIP-seq and ChIP-qPCR. The interaction between ASP and the enhancer elements was confirmed by chromosome conformation capture (3C). Thus, our results suggest that the L1 ASP activation due to aberrant hypomethylation and downstream enhancer interaction plays a key role in the overexpression of lncRNA CASC9 in ESCC.

Functional role of lncRNAs in gastrointestinal malignancies: the peculiar case of small nucleolar RNA host gene family

Long noncoding RNAs (lncRNAs) play crucial roles in normal physiology and are often de-regulated in disease states such as cancer. Recently, a class of lncRNAs referred to as the small nucleolar RNA host gene (SNHG) family have emerged as important players in tumourigenesis. Here, we discuss new findings describing the role of SNHGs in gastrointestinal tumours and summarize the three main functions by which these lncRNAs promote carcinogenesis, namely: competing with endogenous RNAs, modulating protein function, and regulating epigenetic marking. Furthermore, we discuss how SNHGs participate in different hallmarks of cancer, and how this class of lncRNAs may serve as potential biomarkers in cancer diagnosis and therapy.

MicroRNAs: A novel signature in the metastasis of esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a malignant epithelial tumor, characterized by squamous cell differentiation, it is the sixth leading cause of cancer-related deaths globally. The increased mortality rate of ESCC patients is predominantly due to the advanced stage of the disease when discovered, coupled with higher risk of metastasis, which is an exceedingly malignant characteristic of cancer, frequently leading to a high mortality rate. Unfortunately, there is currently no specific and effective marker to predict and treat metastasis in ESCC. MicroRNAs (miRNAs) are a class of small non-coding RNA molecules, approximately 22 nucleotides in length. miRNAs are vital in modulating gene expression and serve pivotal regulatory roles in the occurrence, progression, and prognosis of cancer. Here, we have examined the literature to highlight the intimate correlations between miRNAs and ESCC metastasis, and show that ESCC metastasis is predominantly regulated or regulated by genetic and epigenetic factors. This review proposes a potential role for miRNAs as diagnostic and therapeutic biomarkers for metastasis in ESCC metastasis, with the ultimate aim of reducing the mortality rate among patients with ESCC.

GAS5: A pivotal lncRNA in diabetes mellitus pathogenesis and management

The long non-coding RNA (lncRNA), GAS5, has garnered significant attention recently for its multifaceted involvement in cellular processes, particularly within the context of diabetes. This comprehensive review delves into the intricate molecular interactions associated with GAS5 and their profound implications for understanding, diagnosing, and effectively managing diabetes mellitus. The article begins by highlighting the global prevalence of diabetes and the urgent need for innovative insights into its underlying mechanisms and therapeutic approaches. It introduces GAS5 as a crucial regulator of gene expression, with emerging significance in the context of diabetes-related processes. The core of this review unravels the regulatory network of GAS5 in diabetes, elucidating its impact on various aspects of the disease. It explores how GAS5 influences insulin signaling pathways, glucose metabolism, and the function of β-cells, shedding light on its role in hyperglycemia and insulin resistance. Moreover, the article underscores the clinical relevance of GAS5's interactions by discussing their associations with different diabetes subtypes, predictive value, and potential applications as both diagnostic tools and therapeutic targets. It provides insights into ongoing research endeavours aimed at harnessing the potential of GAS5 for innovative disease management strategies, including the development of RNA-based therapeutics. Concluding with a forward-looking perspective, the abstract highlights the broader implications of GAS5 in the field of diabetes, such as its connection to diabetic complications and its potential for personalized approaches in disease management.

Intron Editing Reveals SNORD-Dependent Maturation of the Small Nucleolar RNA Host Gene GAS5 in Human Cells

The GAS5 gene encodes a long non-coding RNA (lncRNA) and intron-located small nucleolar RNAs (snoRNAs). Its structure, splice variants, and diverse functions in mammalian cells have been thoroughly investigated. However, there are still no data on a successful knockout of GAS5 in human cells, with most of the loss-of-function experiments utilizing standard techniques to produce knockdowns. By using CRISPR/Cas9 to introduce double-strand breaks in the terminal intronic box C/D snoRNA genes (SNORDs), we created monoclonal cell lines carrying continuous deletions in one of the GAS5 alleles. The levels of GAS5-encoded box C/D snoRNAs and lncRNA GAS5 were assessed, and the formation of the novel splice variants was analyzed. To comprehensively evaluate the influence of specific SNORD mutations, human cell lines with individual mutations in SNORD74 and SNORD81 were obtained. Specific mutations in SNORD74 led to the downregulation of all GAS5-encoded SNORDs and GAS5 lncRNA. Further analysis revealed that SNORD74 contains a specific regulatory element modulating the maturation of the GAS5 precursor transcript. The results demonstrate that the maturation of GAS5 occurs through the m6A-associated pathway in a SNORD-dependent manner, which is a quite intriguing epitranscriptomic mechanism.

Non-coding RNAs' function in cancer development, diagnosis and therapy

While previous research on cancer biology has focused on genes that code for proteins, in recent years it has been discovered that non-coding RNAs (ncRNAs)play key regulatory roles in cell biological functions. NcRNAs account for more than 95% of human transcripts and are an important entry point for the study of the mechanism of cancer development. An increasing number of studies have demonstrated that ncRNAs can act as tumor suppressor genes or oncogenes to regulate tumor development at the epigenetic level, transcriptional level, as well as post-transcriptional level. Because of the importance of ncRNAs in cancer, most clinical trials have focused on ncRNAs to explore whether ncRNAs can be used as new biomarkers or therapies. In this review, we focus on recent studies of ncRNAs including microRNAs (miRNAs), long ncRNAs (lncRNAs), circle RNAs (circRNAs), PIWI interacting RNAs (piRNAs), and tRNA in different types of cancer and explore the application of these ncRNAs in the development of cancer and the identification of relevant therapeutic targets and tumor biomarkers. Graphical abstract drawn by Fidraw.

Comprehensive analysis of candidate signatures of long non-coding RNA LINC01116 and related protein-coding genes in patients with hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is a long-term malignancy that causes high morbidities and mortalities worldwide. Notably, long non-coding RNAs (LncRNAs) have been identified as candidate targets for malignancy treatments.

METHODS

LncRNA LINC01116 and its Pearson-correlated genes (PCGs) were identified and analyzed in HCC patients. The diagnostic and prognostic value of the lncRNA was evaluated using data from The Cancer Genome Atlas (TCGA). Further, we explored the target drugs of LINC01116 for clinical application. Relationships between immune infiltration and PCGs, methylation and PCGs were explored. The diagnostic potentials were then validated by Oncomine cohorts.

RESULTS

LINC01116 and the PCG OLFML2B are differentially and highly expressed in tumor tissues (both P ≤ 0.050). We found that LINC01116, TMSB15A, PLAU, OLFML2B, and MRC2 have diagnostic potentials (all AUC ≥ 0.700, all P ≤ 0.050) while LINC01116 and TMSB15A have prognostic significance (both adjusted P ≤ 0.050). LINC01116 was enriched in the vascular endothelial growth factor (VEGF) receptor signaling pathway, mesenchyme morphogenesis, etc. After that, candidate target drugs with potential clinical significance were identified: Thiamine, Cromolyn, Rilmenidine, Chlorhexidine, Sulindac_sulfone, Chloropyrazine, and Meprylcaine. Analysis of immune infiltration revealed that MRC2, OLFML2B, PLAU, and TMSB15A are negatively associated with the purity but positively associated with the specific cell types (all P < 0.050). Analysis of promoter methylation demonstrated that MRC2, OLFML2B, and PLAU have differential and high methylation levels in primary tumors (all P < 0.050). Validation results of the differential expressions and diagnostic potential of OLFML2B (Oncomine) were consistent with those obtained in the TCGA cohort (P < 0.050, AUC > 0.700).

CONCLUSIONS

Differentially expressed LINC01116 could be a candidate diagnostic and an independent prognostic signature in HCC. Besides, its target drugs may work for HCC therapy via the VEGF receptor signaling pathway. Differentially expressed OLFML2B could be a diagnostic signature involved in HCC via immune infiltrates.

The Common LncRNAs of Neuroinflammation-Related Diseases

Spatio-temporal specific long noncoding RNAs (lncRNAs) play important regulatory roles not only in the growth and development of the brain but also in the occurrence and development of neurologic diseases. Generally, the occurrence of neurologic diseases is accompanied by neuroinflammation. Elucidation of the regulatory mechanisms of lncRNAs on neuroinflammation is helpful for the clinical treatment of neurologic diseases. This paper focuses on recent findings on the regulatory effect of lncRNAs on neuroinflammatory diseases and selects 10 lncRNAs that have been intensively studied to analyze their mechanism action. The clinical treatment status of lncRNAs as drug targets is also reviewed. SIGNIFICANCE STATEMENT: Gene therapies such as clustered regularly interspaced short palindrome repeats technology, antisense RNA technology, and RNAi technology are gradually applied in clinical treatment, and the development of technology is based on a large number of basic research investigations. This paper focuses on the mechanisms of lncRNAs regulation of neuroinflammation, elucidates the beneficial or harmful effects of lncRNAs in neurosystemic diseases, and provides theoretical bases for lncRNAs as drug targets.

MSF-UBRW: An Improved Unbalanced Bi-Random Walk Method to Infer Human lncRNA-Disease Associations

Long-non-coding RNA (lncRNA) is a transcription product that exerts its biological functions through a variety of mechanisms. The occurrence and development of a series of human diseases are closely related to abnormal expression levels of lncRNAs. Scientists have developed many computational models to identify the lncRNA-disease associations (LDAs). However, many potential LDAs are still unknown. In this paper, a novel method, namely MSF-UBRW (multiple similarities fusion based on unbalanced bi-random walk), is designed to explore new LDAs. First, two similarities (functional similarity and Gaussian Interaction Profile kernel similarity) of lncRNAs are calculated and fused linearly, also for disease data. Then, the known association matrix is preprocessed. Next, the linear neighbor similarities of lncRNAs and diseases are calculated, respectively. After that, the potential associations are predicted based on unbalanced bi-random walk. The fusion of multiple similarities improves the prediction performance of MSF-UBRW to a large extent. Finally, the prediction ability of the MSF-UBRW algorithm is measured by two statistical methods, leave-one-out cross-validation (LOOCV) and 5-fold cross-validation (5-fold CV). The AUCs of 0.9391 in LOOCV and 0.9183 (±0.0054) in 5-fold CV confirmed the reliable prediction ability of the MSF-UBRW method. Case studies of three common diseases also show that the MSF-UBRW method can infer new LDAs effectively.

Serum non-coding RNAs for diagnosis and stage of liver fibrosis

Background

All chronic liver diseases could lead to liver fibrosis. Accurate diagnosis and stage of fibrosis were important for the medical determination, management, and therapy. Liver biopsy was considered to be the gold criteria of fibrosis diagnosis. However, liver biopsy was an invasive method with some drawbacks. Non‐invasive tests for liver fibrosis included radiologic method and serum‐based test. Radiologic examination was influenced by obesity, cost, and availability. Serum‐based test was widely used in the screening and diagnostic of liver fibrosis. However, the accuracy was still needed to be improved.

Methods

Recent studies showed serum non‐coding RNAs: microRNA, long non‐coding RNA(lncRNA), and circular RNA(circRNA), which have the potentiality to be non‐invasive markers for liver fibrosis. The recent progress was summarized in this review.

Results

These studies showed serum non‐coding RNAs exerted a good diagnostic performance for liver fibrosis. A panel that included several non‐coding RNAs could increase the accuracy of single marker.

Conclusions

Serum microRNAs, lncRNAs, and circRNAs could be potential non‐invasive markers for diagnosis and stage of liver fibrosis. More high‐quality clinical study is needed for further research.

5‑Aza‑dC suppresses melanoma progression by inhibiting GAS5 hypermethylation

The in‑depth study of melanoma pathogenesis has revealed that epigenetic modifications, particularly DNA methylation, is a universal inherent feature of the development and progression of melanoma. In the present study, the analysis of the tumor suppressor gene growth arrest‑specific transcript 5 (GAS5) demonstrated that its expression was downregulated in melanoma, and its expression level had a certain negative association with its methylation modification level. The promoter of GAS5 presented with detectable CpG islands, and methylation‑specific polymerase chain reaction analysis demonstrated that GAS5 was actually modified by methylation in melanoma tissues and cells; however, no methylation modification of GAS5 was detected in normal tissues. Following the treatment of melanoma cells with 5‑Aza‑2'‑deoxycytidine (5‑Aza‑dC), GAS5 methylation was significantly reversed. The analysis of melanoma cell proliferation revealed that 5‑Aza‑dC inhibited A375 and SK‑MEL‑110 cell proliferation in a time‑dependent manner. Further analysis of apoptosis demonstrated that 5‑Aza‑dC significantly increased the apoptosis level of the two cell lines. Moreover, migration analysis of melanoma cells revealed that 5‑Aza‑dC significantly reduced cell migration. Furthermore, 5‑Aza‑dC significantly decreased the invasive ability of the two cell lines. However, when the expression of GAS5 was silenced, the effects of 5‑Aza‑dC on cell proliferation, apoptosis, invasion and migration were not significant. Furthermore, the subcutaneous injection of A375 cells in nude mice successfully resulted in xenograft tumor formation. However, following an intraperitoneal injection of 5‑Aza‑dC, the volume and weight of xenograft tumors and Ki‑67 expression were significantly reduced, and caspase‑3 activity and GAS5 expression were enhanced; following the silencing of GAS5, the antitumor effect of 5‑Aza‑dC was significantly blocked. On the whole, the present study demonstrates that 5‑Aza‑dC inhibits the growth of melanoma, and its function may be related to the methylation modification of GAS5.

Liquid Biopsy in Squamous Cell Carcinoma of the Esophagus and of the Head and Neck

Squamous cell carcinomas of the esophagus (ESCC) and of the head and neck (HNSCC) are two neoplasms that share common risk factors and have the same embryological origin, but a very different prognosis, the 5-year survival of HNSCC being almost double (40–50%) compared to the 5-year survival of ESCC (20%). Current guidelines emphasize the importance of screening for ESCC in patients diagnosed with head and neck cancers. A liquid biopsy is a novel tool for diagnosis, prognostic stratification, and personalized therapy. Liquid biopsy biomarkers for these two malignancies could help both their early detection, facilitate residual disease identification, and provide prognosis information. The present systematic review of the literature was aimed at describing the liquid biopsy biomarkers present in these two malignancies, with an emphasis on potential clinical applications.

Long Non-Coding RNA in Esophageal Cancer: A Review of Research Progress

In recent years, there has been significant progress in the diagnosis and treatment of esophageal cancer. However, owing to the lack of early diagnosis strategies and treatment targets, the prognosis of patients with esophageal cancer remains unsatisfactory. There is an urgent need to identify novel biomarkers and treatment targets for esophageal cancer. With the development of genomics, long-chain non-coding RNAs (LncRNAs), which were once considered transcriptional “noise,” are being identified and characterized rapidly in large numbers. Recent research shows that LncRNAs are closely related to a series of steps in tumor development and play an important regulatory role in DNA replication, transcription, and post-transcriptional regulation. The abnormal expression of LncRNAs leads to tumor cell proliferation, migration, invasion, and treatment resistance. This review focuses on the latest progress in research on the abnormal expression and functional mechanisms of LncRNAs in esophageal cancer. Further, it discusses the potential applications of these findings towards achieving an early diagnosis, improving treatment efficacy, and evaluating the prognosis of esophageal cancer.

LncRNA LINC00115 facilitates lung cancer progression through miR-607/ITGB1 pathway

Dysregulated long noncoding RNAs (lncRNAs) have potential roles in various cancer types. The objective of this study was to investigate the expression and the underlying role of long intergenic nonprotein coding RNA 115 (LINC00115) in lung cancer. The relative expression of LINC00115 and miR-607 in tumor tissues and cells was detected by real-time PCR. After overexpression or knockdown of LINC00115 expression in tumor cells, the changes in the proliferation, migration, and invasion capacities were detected via Counting Kit-8 (CCK-8) assay and transwell assays. The interplay among LINC00115, miR-607, and integrin β1 (ITGB1) was confirmed by bioinformatics analyses and luciferase reporter assay. In addition, tumor cells with LINC00115 knockdown were injected into nude mice to investigate the effect of LINC00115 on tumorigenesis in vivo. LINC00115 was highly expressed in tumor tissues and cells. LINC00115 promoted the malignant properties of tumor cells. Investigation to its molecular mechanism revealed that LINC00115 functioned as a competitive endogenous RNA (ceRNA), regulating the expression of ITGB1 by sponging miR-607 to affect tumor growth. The LINC00115/miR-607/ITGB1 signaling axis might be a novel therapeutic target in lung cancer.

Long noncoding RNA GAS5 in age-related diseases

Aging refers to a natural process and a universal phenomenon in all cells, tissues, organs and the whole organism. Long non-coding RNAs (lncRNAs) are non-coding RNAs with the length of 200 nucleotides. LncRNA growth arrest-specific 5 (lncRNA GAS5) is often down-regulated in cancer. The accumulation of lncRNA GAS5 has been found to be able to inhibit cancer growth, invasion and metastasis, while enhancing the sensitivity of cells to chemotherapy drugs. LncRNA GAS5 can be a signaling protein, which is specifically transcribed under different triggering conditions. Subsequently, it is involved in signal transmission in numerous pathways as a signal node. LncRNA GAS5, with a close relationship to multiple miRNAs, was suggested to be involved in the signaling pathway under three action modes (i.e., signal, bait and guidance). LncRNA GAS5 was found to be involved in different age-related diseases (e.g., rheumatoid arthritis, type 2 diabetes, atherosclerosis, osteoarthritis, osteoporosis, multiple sclerosis, cancer etc.). This study mainly summarized the regulatory effect exerted by lncRNA GAS5 on age-related diseases.

Long Non-Coding RNAs as Potential Diagnostic and Prognostic Biomarkers in Breast Cancer: Progress and Prospects

Breast cancer is the most common malignancy among women worldwide, excluding non-melanoma skin cancer. It is now well understood that breast cancer is a heterogeneous entity that exhibits distinctive histological and biological features, treatment responses and prognostic patterns. Therefore, the identification of novel ideal diagnostic and prognostic biomarkers is of utmost importance. Long non-coding RNAs (lncRNAs) are commonly defined as transcripts longer than 200 nucleotides that lack coding potential. Extensive research has shown that lncRNAs are involved in multiple human cancers, including breast cancer. LncRNAs with dysregulated expression can act as oncogenes or tumor-suppressor genes to regulate malignant transformation processes, such as proliferation, invasion, migration and drug resistance. Intriguingly, the expression profiles of lncRNAs tend to be highly cell-type-specific, tissue-specific, disease-specific or developmental stage-specific, which makes them suitable biomarkers for breast cancer diagnosis and prognosis.

Epigenetically-regulated serum GAS5 as a potential biomarker for patients with chronic hepatitis B virus infection

BACKGROUND

Long non-coding RNA-growth arrest specific transcript 5 (lncRNA-GAS5) plays a suppressive role in activated hepatic stellate cells (HSCs). LncRNAs could circulate in the blood in a cell-free form and serve as promising biomarkers for various human diseases. Herein, we investigated the feasibility of using serum GAS5 as a biomarker for liver fibrosis in chronic hepatitis B (CHB) patients and whether promoter methylation was responsible for GAS5 down-regulation.

METHODS

Serum GAS5 levels were quantified using quantitative real-time PCR in CHB patients and healthy controls. GAS5 promoter methylation was examined in LX-2 cells and cirrhotic tissues.

RESULTS

Compared with the sera from healthy controls, lower GAS5 levels were found in the sera from CHB patients. Receiver operating characteristic curve analysis indicated that serum GAS5 had a significant diagnostic value for liver fibrosis in CHB patients. Serum GAS5 negatively correlated with HAI scores as well as ALT values in CHB patients. GAS5 was additionally reduced in cirrhotic tissues, associated with its hypermethylation promoter. In LX-2 cells, transforming growth factor-β1 treatment led to a reduction in GAS5 expression and an increase in promoter methylation. Hypermethylation of GAS5 was blocked down by DNA methyltransferase (DNMT) inhibitor and restored GAS5 inhibited HSC activation including proliferation and collagen production. Further studies confirmed that GAS5 methylation was mediated by DNMT1.

CONCLUSION

We demonstrate that epigenetically-regulated serum GAS5 could serve as a potential biomarker in CHB patients. Loss of GAS5 is associated with DNMT1-mediated promoter methylation.

Long non-coding RNA LINC01137 contributes to oral squamous cell carcinoma development and is negatively regulated by miR-22-3p

PURPOSE

Long noncoding RNAs (lncRNAs) are emerging as key regulators in cancer initiation and progression. LINC01137 is a recently identified lncRNA of which the functional role in the development of oral squamous cell carcinoma (OSCC) has not been determined yet.

METHODS

We analyzed the expression of LINC01137 using a microarray-based OSCC gene expression dataset (GSE31056), and validated the results obtained using RT-qPCR in 26 pairs of primary OSCC tumor tissues and adjacent non-tumor tissues. The proliferative and invasive effects of LINC01137 on OSCC cells were determined using CCK-8, colony formation and transwell assays, respectively. Targeted binding between miR-22-3p and LINC01137 was verified using a dual luciferase reporter assay.

RESULTS

We found that LINC01137 was significantly upregulated in primary OSCCs. LINC01137 knockdown inhibited OSCC cell proliferation, migration and invasion, whereas LINC01137 overexpression induced opposite effects. LINC01137 upregulation along with p53 inhibition enhanced the malignant transformation of oral cells. In addition, we found that miR-22-3p can directly target LINC01137 through interaction with a putative miR-22-3p-binding site present within the LINC01137 sequence. A significant negative correlation was observed between LINC01137 and miR-22-3p expression in primary OSCC specimens. Exogenous overexpression of miR-22-3p markedly reduced the endogenous expression level of LINC01137 in OSCC cells. Additional functional assays showed that miR-22-3p overexpression enhanced the inhibitory effect of siRNA-mediated LINC01137 silencing on OSCC cell proliferation, migration and invasion, whereas miR-22-3p inhibition had the opposite effect.

CONCLUSIONS

Our results indicate that LINC01137 functions as an oncogenic lncRNA in OSCC. miR-22-3p can directly target LINC01137 and negatively regulate its expression and function.

The emerging role of long noncoding RNAs in esophageal carcinoma: from underlying mechanisms to clinical implications

Long noncoding RNAs (lncRNAs), a type of transcriptional product more than 200 nucleotides in length, have emerged as crucial regulators in human cancers. Accumulating data have recently indicated relationships between lncRNAs and esophageal carcinoma (EC). Of note, lncRNAs act as decoys/sponges, scaffolds, guides, and signals to regulate the expression of oncogenes or tumor suppressors at epigenetic, post-transcriptional, and protein levels, through which they exert their unique EC-driving or EC-suppressive functions. Moreover, the features of EC-related lncRNAs have been gradually exploited for developing novel diagnostic and therapeutic strategies in clinical scenarios. LncRNAs have the potential to be used as diagnostic and prognostic indicators individually or in combination with other clinical variables. Beyond these, although the time is not yet ripe, therapeutically targeting EC-related lncRNAs via gene editing, antisense oligonucleotides, RNA interference, and small molecules is likely one of the most promising therapeutic strategies for the next generation of cancer treatment. Herein, we focus on summarizing EC-driving/suppressive lncRNAs, as well as discussing their different features regarding expression profiles, modes of action, and oncological effects. Moreover, we further discuss current challenges and future developing possibilities of capitalizing on lncRNAs for EC early diagnosis and treatment.

Long Noncoding RNA GAS5 Accelerates Cholangiocarcinoma Progression by Regulating hsa-miR-1297

Background

Long noncoding RNAs (lncRNAs) have been reported as important molecules in cholangiocarcinoma (CCA) occurrence and development. A previous study showed that lncRNA GAS5 (GAS5) was an oncogene in some tumors. But the role of GAS5 in CCA progression reminds unclear. This research was designed to study the expression and potential effects of GAS5 in the progression of CCA.

Methods

The expression of GAS5 in CCA tissues was evaluated through mining of the TCGA and GEPIA databases. qRT-PCR was applied to validate the results in our clinical samples. χ² test was used to analyze the association between the expression level of tissue GAS5 and different clinicopathological parameters of CCA patients. The target gene of GAS5 was predicted by bioinformatic databases, and further verified by luciferase reporter assays. Finally, the role of GAS5 in CCA cells invasion and proliferation was detected by Transwell assay and CCK-8 assay.

Results

Compared to the adjacent nontumor tissues and the normal human intrahepatic biliary epithelial cell, the expression of GAS5 was markedly increased in CCA tissues (p<0.001) and cell lines (p<0.01), respectively. CCA patients with high GAS5 expression tended to present lymph node metastasis (p<0.001) and had advanced clinical stage (p=0.006). The bioinformatics analysis predicted that hsa-miR-1297 was the potential target gene of GAS5, which was validated by luciferase reporter assays. In addition, the function study showed that GAS5 acted as a “sponge” to downregulate hsa-miR-1297, thus modulating CCA cell proliferation and invasion.

Conclusion

GAS5 acts as an endogenous sponge of hsa-miR-1297 to promote CCA cell proliferation and invasion, which might be a potential biomarker and therapeutic target for CCA.

MiR-196: emerging of a new potential therapeutic target and biomarker in colorectal cancer

Deregulation of microRNAs, as key elements in colorectal cancer (CRC) pathogenesis, is correlated with various stages of this cancer. miR-196 is involved in the initiation and progression of a verity of malignances, especially CRC. miR-196 in CRC cells could target different types of genes with oncogenic and/or tumor suppressor function such as HOX genes, GATA6, SOCS1, SOCS3, ANXA1, DFFA, PDCD4, ZG16 and ING5. Therefore, these genes could be up or down-regulated in cells and subsequently change the capacity of CRC cells in terms of tumor development, progression and, response to therapy. Comprehension of miR-196-associated aberrations underlying the CRC pathogenesis might introduce promising targets for therapy. Additionally, it seems that miR-196 expression profiling, especially circulatory exosomal miR-196, might be useful for diagnosis and prognosis determination of the CRC patients. In this review, at first, we summarize the roles of miR-196 in different types of cancers. After that, a detailed discussion about this miRNA and also their targets in CRC pathogenesis, progression, and response to treatment are represented. Moreover, we highlight the potential utilization of miR-196 and its targets as therapeutic targets and novel biomarkers in early detection and prediction of prognosis in CRC patients.

Long non-coding RNA GAS5 in human cancer

Long non-coding RNAs (lncRNAs) constitute a group of >200-nucleotide ncRNA molecules. lncRNAs regulate several cell functions, such as proliferation, apoptosis, invasion and metastasis. Meanwhile, lncRNAs are abnormally expressed in human malignancies, where they suppress or promote tumor growth. The present study focused on growth arrest-specific transcript 5 (GAS5), a well-known lncRNA that acts as a tumor suppressor but is suppressed in multiple types of cancer, including mammary carcinoma, prostate cancer, colorectal cancer, gastric cancer, melanoma, esophageal squamous cell carcinoma, lung cancer, ovarian cancer, cervical cancer, gliomas, osteosarcoma, pancreatic cancer, bladder cancer, kidney cancer, papillary thyroid carcinoma, neuroblastoma, endometrial cancer and liver cancer. Notably, GAS5 is overexpressed in liver cancer, potentially functioning as an oncogene. In the present study, the diagnostic and therapeutic roles of GAS5 in different tumors were reviewed, with a summary of the potential clinical application of the lncRNA, which may help identify novel study directions for GAS5.

LncRNA growth arrest-specific transcript 5 targets miR-21 gene and regulates bladder cancer cell proliferation and apoptosis through PTEN

The aim of this study was to investigate the mechanism by which growth arrest‐specific transcript 5 (GAS5) regulates bladder cancer cells. Bladder cancer samples were collected and tested for experiment. Dual‐luciferase reporter assay was used to verify the downstream target genes for GAS5 and miR‐21. The expression level of GAS5 was decreased and that of miR‐21 was increased, indicating a negative correlation between the two. Patients with high GAS5 level and low miR‐21 level had relatively longer survival rates. GAS5 inhibited bladder cancer cells proliferation and promoted apoptosis, and miR‐21 had the opposite effects. MiR‐21 was a direct target for GAS5, whereas phosphatase and tensin homolog (PTEN) was a direct target gene of miR‐21. Low expression of miR‐21 could reverse the proliferative and antiapoptotic effects caused by GAS5 silencing. High levels of GAS5 and low levels of miR‐21 might be associated with a higher survival rate in bladder cancer patients. GAS5 could exert antiproliferative and proapoptotic effects on bladder cancer cells through miR‐21 and PTEN.

Biological and clinical relevance of metastasis-associated long noncoding RNAs in esophageal squamous cell carcinoma: A systematic review

Esophageal squamous cell carcinoma (ESCC) is a foremost cancer-related death worldwide owing to rapid metastasis and poor prognosis. Metastasis, as the most important reason for death, is biologically a multifaceted process involving a range of cell signaling pathways. Long noncoding RNAs (lncRNAs), as transcriptional regulators, can regulate numerous genomic processes and cellular processes such as cell proliferation, migration, and invasion. LncRNAs have also been shown to involve in/regulate the cancer metastasis-related signaling pathways. Hence, they have increasingly been brought to international attention in molecular oncology research. A number of researchers have attempted to reveal the biological and clinical relevance of lncRNAs in ESCC tumourigenesis and metastasis. The aberrant expression of these molecules in ESCC has regularly been reported to involve in various cellular processes and clinical features, including diagnosis, prognosis, and therapeutic responses. Here, we especially consider the pathways in which lncRNAs act as metastasis-mediated effectors, mainly by interacting with epithelial-mesenchymal transition-associated factors. We review the biological roles of lncRNAs through involving in ESCC metastasis as well as the clinical significance of the metastasis-related lncRNAs in cancer diagnosis and prognosis.

Long non-coding RNA PSMA3-AS1 promotes malignant phenotypes of esophageal cancer by modulating the miR-101/EZH2 axis as a ceRNA

Backgrounds: Emerging evidences has demonstrated that dysregulation of long non-coding RNAs (lncRNAs) is critically involved in esophageal squamous cell carcinoma (ESCC) progression. However, the function of lncRNA PSMA3-AS1 in ESCC is unclear. Therefore, we aimed to explore the functions and potential mechanisms of PSMA3-AS1 in ESCC cells progression.

Results: Here, we found that PSMA3-AS1 expression was significantly up-regulated in ESCC tissues. Forced PSMA3-AS1 expression was correlated with tumor size, distant metastasis, and poor prognosis in ESCC patients. Functionally, PSMA3-AS1-overexpression promoted ESCC cells proliferation, invasion, and migration in vitro. Mechanistically, PSMA3-AS1 up-regulated EZH2 expression by competitively binding to miR-101.

Conclusion: PSMA3-AS1 is significantly up-regulated in ESCC tissues, and the PSMA3-AS1/miR-101/EZH2 axis plays a critical role in ESCC progression. Taken together, our results may provide promising targets for ESCC therapy.

Methods: PSMA3-AS1 and miR-101 expression were explored using qRT-PCR in ESCC tissues and cell lines. Immunohistochemistry assays were carried out to analyze EZH2 (enhancer of zeste homolog) protein expression. RIP, dual-luciferase reporter, fluorescence in situ hybridization, and biotin pull-down assays were used to detect the interactions of PSMA3-AS1, miR-101 and EZH2. The biological functions of PSMA3-AS1 in PSMA3-AS1-altered cells were explored using CCK-8, colony formation, wound healing, and transwell assays in vitro.

lncRNA KLF3-AS1 Suppresses Cell Migration and Invasion in ESCC by Impairing miR-185-5p-Targeted KLF3 Inhibition

Esophageal squamous cell carcinoma (ESCC) is a common cancer occurring in males and females worldwide. Accumulating evidence continues to highlight the crucial roles of long non-coding RNAs (lncRNAs) in the process of tumorigenesis. However, the regulatory mechanism of lncRNAs in ESCC remains unclear. The aim of this study is to elucidate the role of lncRNA Krüppel-like factor 3 antisense RNA 1 (KLF3-AS1) in ESCC by regulating miR-185-5p and KLF3. Initially, ESCC cell spheres with stem cell-like properties were prepared by suspension culture, and subsequently characterized by assessing colony formation ability and stem cell markers. LncRNA KLF3-AS1 was found to be poorly expressed in ESCC and could upregulate the expression of KLF3 by binding to miR-185-5p. lncRNA KLF3-AS1 upregulation was observed to inhibit miR-185-5p, thereby contributing to decreased expression of SOX2 and Oct4 (octamer-binding transcription factor 4). Furthermore, enhancement of lncRNA KLF3-AS1 resulted in reduced colony formation ability, cell invasion and migration, and tumor volume in vivo while promoting cell apoptosis in ESCC through downregulation of miR-185-5p. Collectively, this study indicated that lncRNA KLF3-AS1 inhibited ESCC cell invasion and migration by impairing miR-185-5p-mediated inhibition of KLF3, highlighting a promising novel potential target for ESCC treatment.

Emerging Role of Non-Coding RNAs in Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) is a highly prevalent tumor and is associated with ethnicity, genetics, and dietary intake. Non-coding RNAs (ncRNAs), specifically microRNAs (miRNAs), long ncRNAs (lncRNAs), and circular RNAs (circRNAs) have been reported as functional regulatory molecules involved in the development of many human cancers, including ESCC. Recently, several ncRNAs have been detected as oncogenes or tumor suppressors in ESCC progression. These ncRNAs influence the expression of specific genes or their associated signaling pathways. Moreover, interactions of ncRNAs are evident in ESCC, as miRNAs regulate the expression of lncRNAs, and further, lncRNAs and circRNAs function as miRNA sponges to compete with the endogenous RNAs. Here, we discuss and summarize the findings of recent investigations into the role of ncRNAs (miRNAs, lncRNAs, and circRNAs) in the development and progression of ESCC and how their interactions regulate ESCC development.

Elevation of long non-coding RNA GAS5 and knockdown of microRNA-21 up-regulate RECK expression to enhance esophageal squamous cell carcinoma cell radio-sensitivity after radiotherapy

OBJECTIVE

Lately, lncRNAs have been proposed to function in the radio-sensitivity of tumor cells, yet the role of lncRNA GAS5 in that of esophageal squamous cell carcinoma (ESCC) has scarcely been studied. This study aims to examine GAS5's effects on ESCC cell radio-sensitivity.

METHODS

GAS5, miR-21 and RECK expression in radiation-sensitive and radiation-resistant ESCC tissues, and TE-1 and TE-1-R cells was determined. TE-1 and TE-1-R cells were treated with pcDNA-GAS5 or miR-21 inhibitors to figure out their roles in ESCC cell proliferation, radio-sensitivity, and apoptosis via gain- and loss-of-function experiments.

RESULTS

We found underexpressed GAS5 and RECK, and overexpressed miR-21 in ESCC. GAS5 elevation and miR-21 inhibition reduced viability and the colony formation ability, and enhanced the apoptosis of ESCC cells under radiation.

CONCLUSION

Our study reveals that GAS5 elevation up-regulates RECK expression by down-regulating miR-21 to increase ESCC cell apoptosis after radiation therapy, thus enhancing cell radio-sensitivity.

Association of MicroRNA 196a and 499 Polymorphisms with Development of Cirrhosis and Hepatocellular Carcinoma Post-HCV Infection in Egyptian Patients

Hepatocellular carcinoma (HCC) is the commonest primary tumor of the liver. Chronic HCV infection is the leading cause of end-stage liver disease, HCC and liver-related death in Egypt. Single nucleotide polymorphisms (SNPs) in microRNAs were reported to increase susceptibility to tumorigenesis; affect prognosis and as promising biomarkers in virus-host interactions. This study was conducted to investigate the role of genetic variants of miR-196a2 (rs 11614913) C>T and miR-499 (rs 3746444) A>G in the development of cirrhosis and HCC in Egyptian HCV infected patients. Genotyping of the candidate SNPs was performed by Real Time PCR in 75 HCV-related HCC patients, 75 cirrhotic patients on top of HCV and 75 healthy controls. There was significant difference in miR-499 (rs3746444) genotypes frequency between the three studied groups as the GG genotype was significantly lower in HCC cases than other groups (P = 0.009) while the combined miR-499 (AA+AG) genotypes were significantly higher in HCC cases than other groups (P = 0.005). Also a significant difference was found in miR-499 genotypes frequency when compared between HCC and cirrhosis groups as the GG genotype was significantly lower in HCC cases than cirrhosis group (P = 0.006) while the combined miR-499 (AA+AG) genotypes were significantly higher in HCC cases than in cirrhosis group (P = 0.003) [OR (95% CI) = 0.131 (0.028-0.601)]. The frequency of the G allele was significantly lower in HCC than other groups (P = 0.024) and significantly lower in HCC than normal group (P = 0.006) [OR (95%CI) = 0.501 (0.304-0.825)]. For miR-196a2 (rs11614913) C>T polymorphisms, no significant association was found with HCC risk. Our study concluded that the G allele of miR-499 is associated with lower risk of HCV related HCC development. No significant association of miR-196a2 (rs 11614913), genotypes or alleles with risk for HCC development, could be detected.<br />.

Novel Tumor Suppressor lncRNA Growth Arrest-Specific 5 (GAS5) In Human Cancer

Long noncoding RNAs (lncRNAs) play crucial regulatory roles in fundamental biological processes, and deregulations of lncRNAs have been linked to numerous human diseases, especially cancers. Of particular interest in this regard is lncRNA GAS5, which is mainly identified as a tumor suppressor in several cancers. GAS5 was significantly low expressed in multiple cancers and was associated with clinic-pathological characteristics and patient survival, indicating a novel potential diagnostic and prognostic biomarker, and a therapeutic target for cancer. Functionally, GAS5 is involved in cell proliferation, metastasis, invasion, apoptosis, epithelial-mesenchymal transition (EMT), and drug resistance, among others, via multiple molecular mechanisms, such as binding to DNA sequences, forming RNA-DNA triplex complex, triggering or suppressing the expression of genes, binding proteins to form chromatin-modifying complex, which activates or represses gene expression, and acting as miRNA sponge to suppress miRNA expression, leading to regulation of miRNA target genes. This review provides an overview of the current state of knowledge and role of GAS5 in clinical relevance, biological functions and molecular mechanisms underlying the dysregulation of expression and function of GAS5 in cancer. Finally, the potential prospective role as diagnostic and prognostic biomarker and therapeutic target in cancer is discussed.

The Growth-Arrest-Specific (GAS)-5 Long Non-Coding RNA: A Fascinating lncRNA Widely Expressed in Cancers

Long non-coding RNA (lncRNA) genes encode non-messenger RNAs that lack open reading frames (ORFs) longer than 300 nucleotides, lack evolutionary conservation in their shorter ORFs, and do not belong to any classical non-coding RNA category. LncRNA genes equal, or exceed in number, protein-coding genes in mammalian genomes. Most mammalian genomes harbor ~20,000 protein-coding genes that give rise to conventional messenger RNA (mRNA) transcripts. These coding genes exhibit sweeping evolutionary conservation in their ORFs. LncRNAs function via different mechanisms, including but not limited to: (1) serving as “enhancer” RNAs regulating nearby coding genes in cis; (2) functioning as scaffolds to create ribonucleoprotein (RNP) complexes; (3) serving as sponges for microRNAs; (4) acting as ribo-mimics of consensus transcription factor binding sites in genomic DNA; (5) hybridizing to other nucleic acids (mRNAs and genomic DNA); and, rarely, (6) as templates encoding small open reading frames (smORFs) that may encode short proteins. Any given lncRNA may have more than one of these functions. This review focuses on one fascinating case—the growth-arrest-specific (GAS)-5 gene, encoding a complicated repertoire of alternatively-spliced lncRNA isoforms. GAS5 is also a host gene of numerous small nucleolar (sno) RNAs, which are processed from its introns. Publications about this lncRNA date back over three decades, covering its role in cell proliferation, cell differentiation, and cancer. The GAS5 story has drawn in contributions from prominent molecular geneticists who attempted to define its tumor suppressor function in mechanistic terms. The evidence suggests that rodent Gas5 and human GAS5 functions may be different, despite the conserved multi-exonic architecture featuring intronic snoRNAs, and positional conservation on syntenic chromosomal regions indicating that the rodent Gas5 gene is the true ortholog of the GAS5 gene in man and other apes. There is no single answer to the molecular mechanism of GAS5 action. Our goal here is to summarize competing, not mutually exclusive, mechanistic explanations of GAS5 function that have compelling experimental support.

Knockdown of LINC01116 inhibits cell migration and invasion in head and neck squamous cell carcinoma through epithelial-mesenchymal transition pathway

Long noncoding RNAs (lncRNAs) are linked to tumor development and progression. The aim of this study was to determine the prognostic significance and biological role of LINC01116 in head and neck squamous cell carcinoma (HNSCC). We identified 21 aberrantly expressed lncRNAs specific to HNSCC that were common in two microarray datasets. LINC01116 was highly overexpressed in HNSCC tissues and was correlated to shorter overall survival and relapse-free survival duration, as analyzed by the online Gene Expression Profiling Interactive Analysis platform. LINC01116 was also overexpressed in oral squamous cell carcinoma and nasopharyngeal carcinoma tissues, and LINC01116 silencing significantly inhibited the migration and invasion capacities of both cell lines by blocking the epithelial-mesenchymal transition process. In addition, 125 coexpressing genes were identified by circlncRNAnet, and were mainly located on human autosomes and enriched in transforming growth factor-β signaling pathway. These findings indicate that LINC01116 might be a potential therapeutic target for HNSCC.

MALAT1 modulates miR-146's protection of microvascular endothelial cells against LPS-induced NF-κB activation and inflammatory injury

To investigate the role of miR-146 and its possible relationship with MALAT1 in LPS-induced inflammation in human microvascular endothelial cells (HMECs), HMEC-1 cells were treated with LPS to construct an inflammatory injury cell model, and the cell viability, TNF-α and IL-6 secretion and the expression levels of VCAM-1, SELE and ICAM-1 were analysed as markers of inflammatory injury. The regulation mechanisms of miR-146 interacted with MALAT1 and the downstream NF-κB signalling were also verified by dual-luciferase assay and knockdown technology. LPS significantly decreased the cell viability, increased levels of VCAM-1, SELE and ICAM-1 and also up-regulated miR-146a/b, TNF-α and IL-6 in a dose-dependent manner. Over-expression of miR-146a resulted in down-regulation of TNF-α and IL-6, as well as VCAM-1, SELE and ICAM-1, while inhibition of miR-146a led to opposite results. The dual-luciferase reporter assay showed both miR-146a and miR-146b directly targeted and negatively regulated the expression of MALAT1. Silencing of MALAT1 suppressed LPS-induced NF-κB activation and TNF-α and IL-6 secretion, reducing the cell inflammatory injury, but these changes were reversed after combined treatment with miR-146a inhibitor. Taken together, we demonstrate that miR-146 protects HMECs against inflammatory injury by inhibiting NF-κB activation. This process is modulated by MALAT1.

Up-regulated lncRNA GAS5 promotes chemosensitivity and apoptosis of triple-negative breast cancer cells

Up to accomplishment of this study, the role of long non-coding RNAs (lncRNAs) in breast cancer has been investigated in several researches. Nevertheless, its association with the chemosensitivity of cancer was little known. Therefore, this study is focused on lncRNA GAS5 and its influence in the chemosensitivity of triple-negative breast cancer (TNBC). Expression of GAS5 in TNBC tissues and cells was detected by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and its methylation was evaluated using methylation-specific polymerase chain reaction (MSP). Moreover, in order to define the contributory role of GAS5 in TNBC, GAS5 expression, proliferation, and apoptosis of TNBC cells were detected by a series of experiment. Finally, the effects of GAS5 in vivo were investigated by measuring tumor formation in nude mice. GAS5 was poorly expressed in TNBC tissues and cells, which could regulate the progression of TNBC. The methylation of CpG island in the promoter region of GAS5 in MDA-MB-231 and MDA-MB-468 cells was decreased, while GAS5 expression in cells was increased. Overexpressed GAS5 reduced the inhibitory concentration (IC50) value and the cell proliferation of TNBC, and promoted their apoptosis, so as to delay the progression of TNBC. Our study provides evidence that up-regulated GAS5 suppressed the progression of TNBC and promoted chemosensitivity and apoptosis of TNBC cells. Thus, GAS5 may be a potential candidate for the treatment of TNBC.

The role of long non-coding RNA GAS5 in cancers

Long non-coding RNAs (lncRNAs) have shown potential as a biomarker in the diagnosis and prognosis in multiple cancers. LncRNAs are dysregulated in various cancers, playing either oncogenic or tumor suppressive roles. Emerging evidences have proved that the growth arrest-specific 5 (GAS5) lncRNA can function as a tumor suppressor in several cancers. LncRNA GAS5 is downregulated in many types of cancer, regulating cellular processes such as cell proliferation, apoptosis and invasion. The low level of GAS5 expression often elevates capacity of proliferation and predicts poorer prognosis in some cancers. This review aims to summarize the recent published literature on the biogenesis, regulation mechanism and function of GAS5 in different types of cancers and explore its potential for cancer diagnosis, prognosis and treatment.

Progress in research of long non-coding RNA GAS5 in human tumors

Growth arrest-special transcript 5 (GAS5) is a long non-coding RNA (lncRNA), located on chromosome 1 of the human genome, and it plays an important regulatory role in biological processes such as cell proliferation, apoptosis, migration, and invasion. Recent studies have shown that GAS5 is down-expressed in most tumor tissues, which is closely related to tumorigenesis, tumor development, and prognosis. A better understanding of the pathogenetic mechanisms and biologic functions of lncRNA GAS5 may offer novel opportunities for diagnosis and therapy of tumors. In this review, we summarize the latest research progress of lncRNA GAS5 in various human carcinomas.

Altered expression of long non-coding RNA GAS5 in digestive tumors

Cancer has become one of the most important diseases that affect human health and life. The effects of cancer in the digestive system are particularly prominent. Recently, long non-coding RNA (lncRNA) has attracted the attention of more and more researchers and has become an emerging field of gene research. The lncRNA growth arrest-specific 5 (GAS5) is a novel lncRNA that has attracted the attention of researchers in recent years and plays an important role in the development of tumors, especially in digestive system tumors. GAS5 was first identified in a mouse cDNA library. It was generally considered that it has the role of tumor suppressor genes, but there are still studies that have a certain ability to promote cancer. Furthermore, the 5-bp indel polymorphism (rs145204276) in the GAS5 promoter region also has a carcinogenic effect. The discovery of GAS5 and in-depth study of single nucleotide polymorphism (SNP) mechanism can provide a new way for the prevention and treatment of digestive system tumors.

Long noncoding RNA HOTTIP mediates SRF expression through sponging miR-150 in hepatic stellate cells

HOXA transcript at the distal tip (HOTTIP) has been shown to be up‐regulated in a variety of cancers and is identified as an oncogenic long noncoding RNA. However, the biological role of HOTTIP in liver fibrosis is unclear. Here, we reported that HOTTIP was specifically overexpressed in activated hepatic stellate cells (HSCs). HOTTIP knockdown suppressed the activation and proliferation of HSCs. Luciferase reporter assay showed that HOTTIP and serum response factor (SRF) were targets of miR‐150. RNA binding protein immunoprecipitation assay indicated the interaction between miR‐150 and HOTTIP. Further study revealed that HOTTIP increased SRF expression as a competing endogenous RNA for miR‐150, thus prompting HSC activation. Taken together, we provide a novel HOTTIP‐miR‐150‐SRF signalling cascade in liver fibrosis.

Long Non-Coding RNA (lncRNA) Growth Arrest Specific 5 (GAS5) Suppresses Esophageal Squamous Cell Carcinoma Cell Proliferation and Migration by Inactivating Phosphatidylinositol 3-kinase (PI3K)/AKT/Mammalian Target of Rapamycin (mTOR) Signaling Pathway

BACKGROUND lncRNA GAS5 acts as a tumor-suppressor gene in various types of malignancies, but its involvement in esophageal cancer has not been well studied. MATERIAL AND METHODS A total of 112 patients with esophageal cancer and 55 volunteers with normal physiological conditions were included in this study. Tumor tissues and adjacent healthy tissues were collected from esophageal cancer patients and blood was extracted from patients and controls. Expression of GAS5 in those tissues was detected by qRT-PCR. All patients were followed up for 5 years and diagnostic and prognostic values of serum GAS5 for esophageal cancer were investigated by ROC curve analysis and survival curve analysis, respectively. Effects of GAS5 expression on cell proliferation and migration were investigated by CCK-8 assay and Transwell cell migration assay, respectively. Effects of GAS5 overexpression on expression of PI3K/AKT/mTOR-related proteins were explored by Western blot analysis. RESULTS GAS5 expression level was lower in tumor tissues than in adjacent healthy tissues. Serum level of GAS5 was lower in cancer patients than in healthy controls, and serum level of GAS5 was decreased with increase in stage of primary tumor (T stage). GAS5 overexpression inhibited tumor cell proliferation and migration, while treatment with PI3K activator reduced the inhibitory effects. GAS5 overexpression decreased the expression level of PI3K and phosphorylation levels of Akt and mTOR in esophageal cancer cells, while PI3K activator treatment showed no significant effects on GAS5 expression. CONCLUSIONS GAS5 was downregulated in esophageal cancer patients compared to healthy controls, and GAS5 overexpression suppressed proliferation and migration of esophageal cancer cells by inactivating the PI3K/AKT/mTOR pathway.

Lowly-expressed lncRNA GAS5 facilitates progression of ovarian cancer through targeting miR-196-5p and thereby regulating HOXA5

PURPOSE

This investigation was aimed at extrapolating whether and how lncRNA GAS5, miR-196a-5p and HOXA5 altered progression of ovarian cancer (OA).

METHOD

Totally 195 pairs of OA tissues and adjacent normal tissues were collected. Also si-GAS5, pcDNA-GAS5, miR-196a-5p mimic, miR-196a-5p inhibitor and negative control (NC) were, respectively, transfected into OA cells. Besides, dual-luciferase reporter gene assay was performed to validate the targeted relationships between GAS5 and miR-196a-5p, as well as between miR-196a-5p and HOXA5. The impacts of GAS5, miR-196a-5p and HOXA5 on viability, proliferation and apoptosis of OA cells were appraised via conduction of colony formation assay, MTT assay and flow cytometry assay.

RESULT

Lower GAS5 expression and higher miR-196a-5p expression were associated with larger tumor size (≥5 cm) and more advanced FIGO stage (III-IV) of OA patients (P < 0.05). Transfection of si-GAS5, miR-196a-5p mimic or si-HOXA5 conferred OA cells with stronger viability, faster proliferation and smaller percentage of apoptosis (P < 0.05). After injecting mice models with si-GAS5, miR-196a-5p mimic or si-HOXA5, a larger tumor size was also observed within the rats (P < 0.05). GAS5 was indicated to directly target miR-196a-5p and modify its expression, and the targeted relationship also seemed to exist between miR-196a-5p and HOXA5 (P < 0.05). The HOXA5 was found to reverse the effects imposed by miR-196a-5p on viability, proliferation and apoptosis of OA cells (P < 0.05).

CONCLUSION

LncRNA GAS5 depressed OA development by targeting miR-196a-5p and thereby down-regulating HOXA5 expression, providing substance for developing lncRNA-based strategies to treat OA.

Long non-coding RNA GAS5 is induced by interferons and plays an antitumor role in esophageal squamous cell carcinoma

The long non-coding RNA GAS5 has been reported as a tumor suppressor in many cancers. However, its functions and mechanisms remain largely unknown in esophageal squamous cell carcinoma (ESCC). In this study, we found that GAS5 was over-expressed in ESCC tissue compared with that in normal esophageal tissue in a public database. Functional studies showed that GAS5 could inhibit ESCC cell proliferation, migration and invasion in vitro. Further analysis revealed that GAS5 was regulated by interferon (IFN) responses via the JAK-STAT pathway. Moreover, as an IFN-stimulated gene (ISG), GAS5 was a positive regulator of IFN responses. The feedback loop between GAS5 and the IFN signaling pathway plays an important antitumor role in ESCC, thus providing novel potential therapeutic targets.