Dysregulation of non-coding RNAs in gastric cancer

The Most Recent Insights into the Roots of Gastric Cancer

Helicobacter pylori (H. pylori) is the most common bacterial infection worldwide, usually being acquired during childhood, and its persistence into adulthood represents one of the main contributors of gastric carcinogenesis. Based on these statements, it would be of great importance to know if the most early premalignant transformation occurs in children or later since, this would enable the development of effective anti-tumorigenesis strategies. The interplay between H. pylori virulence factors, the host's responses modified by this infection, and the gastric microecology are complex and eventually lead to the development of gastric cancer in susceptible individuals. Several biomarkers were identified as major contributors of this long-lasting process, such as pepsinogens, gastrin 17, lipid-, glucose- and iron-metabolism parameters, immunity players, aberrant bacterial DNA methylation, H. pylori virulence factors, and hallmarks of gastric dysbiosis. Several of these biomarkers were also identified in children with H. pylori infection, independently of the presence of premalignant lesions, which were also proven to be present in a subgroup of H. pylori-infected children, especially those carrying extremely virulent strains. Therefore, the most incipient premalignant gastric changes might indeed occur early during childhood, opening a promising research gate for further studies to delineate the border between infection and cancer.

Role of Angiogenesis and Its Biomarkers in Development of Targeted Tumor Therapies

Angiogenesis plays a significant role in the human body, from wound healing to tumor progression. "Angiogenic switch" indicates a time-restricted event where the imbalance between pro- and antiangiogenic factors results in the transition from prevascular hyperplasia to outgrowing vascularized tumor, which eventually leads to the malignant cancer progression. In the last decade, molecular players, i.e., angiogenic biomarkers and underlying molecular pathways involved in tumorigenesis, have been intensely investigated. Disrupting the initiation and halting the progression of angiogenesis by targeting these biomarkers and molecular pathways has been considered as a potential treatment approach for tumor angiogenesis. This review discusses the currently known biomarkers and available antiangiogenic therapies in cancer, i.e., monoclonal antibodies, aptamers, small molecular inhibitors, miRNAs, siRNAs, angiostatin, endostatin, and melatonin analogues, either approved by the U.S. Food and Drug Administration or currently under clinical and preclinical investigations.

Metallomic Signatures of Lung Cancer and Chronic Obstructive Pulmonary Disease

Lung cancer (LC) is the leading cause of cancer deaths, and chronic obstructive pulmonary disease (COPD) can increase LC risk. Metallomics may provide insights into both of these tobacco-related diseases and their shared etiology. We conducted an observational study of 191 human serum samples, including those of healthy controls, LC patients, COPD patients, and patients with both COPD and LC. We found 18 elements (V, Al, As, Mn, Co, Cu, Zn, Cd, Se, W, Mo, Sb, Pb, Tl, Cr, Mg, Ni, and U) in these samples. In addition, we evaluated the elemental profiles of COPD cases of varying severity. The ratios and associations between the elements were also studied as possible signatures of the diseases. COPD severity and LC have a significant impact on the elemental composition of human serum. The severity of COPD was found to reduce the serum concentrations of As, Cd, and Tl and increased the serum concentrations of Mn and Sb compared with healthy control samples, while LC was found to increase Al, As, Mn, and Pb concentrations. This study provides new insights into the effects of LC and COPD on the human serum elemental profile that will pave the way for the potential use of elements as biomarkers for diagnosis and prognosis. It also sheds light on the potential link between the two diseases, i.e., the evolution of COPD to LC.

Investigations into the impact of non-coding RNA on the sensitivity of gastric cancer to radiotherapy

Non-coding RNAs (ncRNAs) are a newly discovered functional RNA different from messenger RNA, which can participate in regulating the occurrence and development of tumors. More and more research results show that ncRNAs can participate in the regulation of gastric cancer (GC) radiotherapy response, and its mechanism may be related to its effect on DNA damage repair, gastric cancer cell stemness, cell apoptosis, activation of epidermal growth factor receptor signaling pathway, etc. This article summarizes the relevant mechanisms of ncRNAs regulating the response to radiotherapy in gastric cancer, which will be directly important for the introduction of ncRNAs particularly microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) into clinical medicine as biomarkers and therapeutic targets.

LncRNA DLEU2 silencing impedes the migration, invasion and EMT in gastric cancer cell by suppressing PI3K/AKT signaling pathway

Context: The high expression of long non-coding RNA deleted in lymphocytic leukaemia 2 (lncRNA DLEU2) has been confirmed in gastric cancer (GC).Objective: However, the detailed mechanism concerning its involvement in GC remained unclear, which we aimed to explore in this study.Materials and methods: LncRNA DLEU2 expression in GC was estimated by bioinformatic analysis, and the relationship between the expression of DLEU2 and the clinicopathological characteristics of patients with GC was performed. qRT-PCR was employed to detect the expression of lncRNA DLEU2 and confirm the transfection efficiency following the knockdown or overexpression of DLEU2. Functional assays, including CCK-8, flow cytometry, scratching test and Transwell assays, were used to determine the role of DLEU2 in tumor phenotypes. The effects of DLEU2 on the PI3K/Akt pathway were detected by western blot. For elucidating the functions of DLEU2/PI3K/Akt axis in GC, we inhibited the PI3K/Akt pathway in rescue experiments, and evaluated the expression levels of epithelial-mesenchymal transition (EMT)-related proteins by western blot.Results: The expression of DLEU2 was aberrantly up-regulated in GC tissues and cells, which was correlated with the degree of tumor differentiation, cancer antigen 19-9 (CA19-9) and Lauren histologic classification of patients with GC. Silencing of DLEU2 induced apoptosis, attenuated viability, migration and invasion as well as inhibited the PI3K/Akt signaling pathway in GC cells. Mechanistically, the DLEU2/PI3K/Akt axis promoted the progression of GC and the EMT by down-regulating the expression of E-Cadherin and up-regulating those of N-Cadherin and Vimentin.Discussion and conclusions: LncRNA DLEU2 promoted the migration, invasion and EMT in GC by activating the PI3K/Akt pathway.

MiR-874-3p represses the migration and invasion yet promotes the apoptosis and cisplatin sensitivity via being sponged by long intergenic non-coding RNA 00922 (LINC00922) and targeting Glycerophosphodiester Phosphodiesterase Domain Containing 5 (GDPD5) in gastric cancer cells

Our study mainly reports the specific mechanisms of microRNA (miR)-874-3p on drug resistance in gastric cancer (GC). Clinical specimen was collected. The upstream long non-coding RNA (lncRNA) and the downstream gene of miR-874-3p were predicted using bioinformatic analysis with the results being ascertained with dual-luciferase reporter assay. The viability, apoptosis, migration and invasion of transfected GC cells with or without cisplatin (DDP) treatment were evaluated by Cell Counting Kit-8 (CCK-8), flow cytometric, Scratch, and Transwell assays. An animal xenograft model was constructed. Expressions of long intergenic non-coding RNA 00922 (LINC00922), miR-874-3p and potential target genes were quantified by quantitative real-time polymerase-chain reaction (qRT-PCR) and Western blot. MiR-874-3p, which was lower-expressed in drug-resistant GC tissues and cells, was upregulated to repress the viability, migration and invasion but enhance the apoptosis and sensitivity in GC cells with or without DDP resistance. Downregulation of miR-874-3p eliminated the effects of silenced LINC00922, a upstream lncRNA of miR-874-3p, on cell viability, apoptosis, migration and invasion, as well as the expressions of Glycerophosphodiester Phosphodiesterase Domain Containing 5 (GDPD5) and the downstream gene of miR-874-3p in DDP-resistant GC cells. GDPD5 silencing diminished the effects of miR-874-3p downregulation on GDPD5 expression, viability, migration and invasion of DDP-resistant GC cells. Additionally, LINC00922 silencing enhanced the inhibitory effect of DDP on tumor growth, whereas reversing the effects of DDP on LINC00922, miR-874-3p and GDPD5 expressions in tumors. MiR-874-3p, an miRNA, which is sponged by LINC00922 and targets GDPD5, inhibits the GC progression yet enhances the DDP sensitivity in GC.

MicroRNA-217: a therapeutic and diagnostic tumor marker

INTRODUCTION

Cancer as one of the most common causes of death has always been one of the major health challenges globally. Since, the identification of tumors in the early tumor stages can significantly reduce mortality rates; it is required to introduce novel early detection tumor markers. MicroRNAs (miRNAs) have pivotal roles in regulation of cell proliferation, migration, apoptosis, and tumor progression. Moreover, due to the higher stability of miRNAs than mRNAs in body fluids, they can be considered as non-invasive diagnostic or prognostic markers in cancer patients.

AREAS COVERED

In the present review we have summarized the role of miR-217 during tumor progressions. The miR-217 functions were categorized based on its target molecular mechanisms and signaling pathways.

EXPERT OPINION

It was observed that miR-217 mainly exerts its function by regulation of the transcription factors during tumor progressions. The WNT, MAPK, and PI3K/AKT signaling pathways were also important molecular targets of miR-217 in different cancers. The present review clarifies the molecular biology of miR-217 and paves the way of introducing miR-217 as a non-invasive diagnostic marker and therapeutic target in cancer therapy.

Potential Non-invasive Biomarkers of Helicobacter pylori-Associated Gastric Cancer

BACKGROUND

Gastric cancer (GC) remains the fifth most common incident cancer with the highest incidence in East Asian countries and the third leading cause of cancer death worldwide. The causal association between non-cardia GC and Helicobacter pylori (H. pylori) has been firmly documented by clinical and epidemiological studies. According to the guidelines for diagnosis and treatment of H. pylori infection, eradication therapy is strongly recommended. Early detection of GC is critical and can save lives through rapid technological advancement. At present, endoscopy remains the most efficient technique. However, it is invasive and costs highly.

METHODS

An extensive bibliographic search was performed via PubMed/Medline, Web of Science, and EBSCO host databases to select studies conducted within the past 8 years. Forty-six relevant analyses were encompassed in this review.

RESULTS

Several non-invasive candidate biomarkers associated with H. pylori, divided into virulence markers, transcriptome markers, genomic markers, and inflammatory markers, have been shown to be potential predictors of GC at an early stage.

CONCLUSION

The discovery of non-invasive biomarkers offers new perspectives for screening, early detection, and monitoring of individuals at risk.

LncRNA-HEIH is a Novel Diagnostic and Predictive Biomarker in Gastric Cancer

Background: Gastric cancer (GC) is associated with a high mortality rate. Long noncoding RNA (lncRNA)-high expressed in hepatocellular carcinoma (HEIH) has recently gained interest as a marker for the detection of several cancer types. This study was designed to uncover the function of lncRNA-HEIH in GC. Materials and Methods: Oncomine was used to analyze HEIH expression in cancerous and paired noncancerous tissues of GC patients. Subsequently, the expression levels of HEIH in GC cells was determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). In addition, the effects of HEIH expression level on clinicopathological parameters and prognosis were further studied by statistical analysis and Kaplan-Meier survival curves. GC cell proliferation and the influence of HEIH on the sensitivity of cells to oxaliplatin following HEIH knockdown were assessed using sulforhodamine blue (SRB) assays in the MKN45 and AGS cell lines. In addition, the expression levels of p53 were detected by RT-qPCR following knockdown of HEIH. Results: The lncRNA-HEIH was highly expressed in both GC tissues and GC cell lines. Patients with high HEIH expression were associated with medium-high differentiation (p = 0.0058), distant metastasis (M, p = 0.0378), lymph node metastasis (N, p = 0.0083), and a deeper tumor invasion (T, p = 0.0204). The elevated expression levels of HEIH in GC patients were associated with a worse prognosis compared to GC patients with low HEIH expression. This finding was supported by the parameters overall survival (p = 3.3e-06), first progression (p = 0.00028), and postprogression (p = 1.5e-08). Downregulation of HEIH expression inhibited cell proliferation, enhanced oxaliplatin sensitivity, and induced the expression of p53 in MKN45 and AGC cells. Conclusion: These findings provide evidence that HEIH may be useful as a prognostic biomarker in GC. This lncRNA may also serve as a potential therapeutic target in GC patients.

Dysregulation of lncRNA in Helicobacter pylori-Infected Gastric Cancer Cells

Helicobacter pylori (H. pylori) infection is the most common cause of gastric cancer (GC). This microorganism is genetically diverse; GC is caused by several genetic deregulations in addition to environmental factors and bacterial virulence factors. lncRNAs (long noncoding RNAs) are significant biological macromolecules in GC, have specific functions in diseases, and could be therapeutic targets. Altered lncRNAs can lead to the abnormal expression of adjacent protein-coding genes, which may be important in cancer development. Their mechanisms have not been well understood, so we are going to investigate the risk of GC in a population with both high lncRNA and H. pylori infection.

miR-1301-3p Promotes Cell Proliferation and Facilitates Cell Cycle Progression via Targeting SIRT1 in Gastric Cancer

So far, many existing evidences indicate that microRNAs (miRNA) are closely associated with the tumorigenesis and progression of various tumors. It has been reported that miR-1301-3p is abnormally expressed in several malignant tumors. However, the role of miR-1301-3p in gastric cancer (GC) remains unclear and is worth studying. Through qRT-PCR, the expression of miR-1301-3p and SIRT1 were detected in GC tissues and cells. The cell proliferation and cell cycle were measured through CCK-8 assay and clone formation assay. Dual luciferase reporter assay was used to determine the target of miR-1301-3p. Though tumorigenesis assay, we monitored the effect of miR-1301-3p on GC cell growth in vivo. miR-1301-3p was upregulated in GC tissues and cells in our study. Overexpression of miR-1301-3p accelerated GC cell proliferation, cell cycle progression and tumorigenesis. Notably, altering the expression miR-1301-3p caused deregulation of Cyclin D1, CDK4, c-Myc and P21. Furthermore, SIRT1 was the direct target of miR-1301-3p by luciferase reporter assay. After transfecting with miR-1301-3p inhibitor, we found that knockdown of SIRT1 could enhance the ability of proliferation. Our results identify miR-1301-3p as a novel potential therapeutic target that is associated with the tumorigenesis and progression of gastric cancer.

The Role and Expression of Angiogenesis-Related miRNAs in Gastric Cancer

Gastric cancer (GC) is the fifth most frequently diagnosed malignant tumor and the third highest cause of cancer mortality worldwide. For advanced GC, many novel drugs and combinations have been tested, but results are still disappointing, and the disease is incurable in the majority of cases. In this regard, it is critical to investigate the molecular mechanisms underlying GC development. Angiogenesis is one of the hallmarks of cancer with a fundamental role in GC growth and progression. Ramucirumab, a monoclonal antibody that binds to vascular endothelial growth factor-2 (VEGFR-2), is approved in the treatment of advanced and pretreated GC. However, no predictive biomarkers for ramucirumab have been identified so far. Micro RNAs (miRNAs) are a class of evolutionarily-conserved single-stranded non-coding RNAs that play an important role (via post-transcriptional regulation) in essentially all biologic processes, such as cell proliferation, differentiation, apoptosis, survival, invasion, and migration. In our review, we aimed to analyze the available data on the role of angiogenesis-related miRNAs in GC.

Long Noncoding RNAs: New Regulators of Resistance to Systemic Therapies for Gastric Cancer

Gastric cancer (GC) is the second leading cause of cancer mortality and the fourth most commonly diagnosed malignant disease, with approximately 951,000 new cases diagnosed and approximately 723,000 cases of mortality each year. The highest mortality rate of GC is in East Asia, and the lowest is in North America. A large number of studies have demonstrated that GC patients are characterized by higher morbidity, metastasis rates, and mortality and lower early diagnosis rates, radical resection rates, and 5-year survival rates. All cases of GC can be divided into two important stages, namely, early- and advanced-stage GC, and the stage mainly determines the treatment strategy for and the therapeutic effect in GC patients. Patients with early-stage GC undergo radical surgery followed by chemotherapy, and the 5-year survival rate can be as high as 90%. However, patients with advanced-stage GC cannot undergo radical surgery because they are at risk for metastasis; therefore, they can choose only radiotherapy or chemotherapy and have a poor prognosis. Based on the lack of specific clinical manifestations and detection methods, most GC patients (>70%) are diagnosed in the advanced stage; therefore, continued efforts toward developing treatments have been focused on advanced-stage GC patients and include molecular targeted therapy, immunotherapy, and small molecular therapy. Nevertheless, in recent years, accumulating evidence has indicated that small molecules, especially long noncoding RNAs (lncRNAs), are involved in the occurrence, development, and progression of GC, and their abundantly dysregulated expression has been identified in GC tissues and cell lines. Therefore, lncRNAs are considered easily detectable molecules and ideal biomarkers or target-specific agents for the future diagnosis or treatment of GC. In this review, we primarily discuss the status of GC, the role of lncRNAs in GC, and the emerging systemic treatments for GC.

Integrated Profiling Revealed Potential Regulatory Networks Among Long Noncoding RNAs and mRNAs in Mucosal Gastric Cancer

Gastric cancer is one of the most commonly occurring cancers worldwide. Investigation of long noncoding RNAs is of increasing interest, particularly in relation to their contribution to progression and prognosis of gastric cancers; however, insufficient studies been performed investigating the part of long noncoding RNAs play in gastric cancer carcinogenesis. Patterns of dysregulated long noncoding RNA and messenger RNA between mucosa gastric cancer and adjacent normal tissues were identified using long noncoding RNAs microarray analysis. Quantitative real-time polymerase chain reaction was conducted as a means to verify the obtained data. Both Gene Ontology and Kyoto Encyclopedia of Genes and Genomes  (KEGG) pathway analyses were subsequently used to investigate the function of dysregulated long noncoding RNAs and messenger RNAs. Cis and trans action was used to predict the possible targets of long noncoding RNAs, and a coexpression network was created to simulate the complex intergenic interactions. Ninety-five dysregulated long noncoding RNAs and 123 messenger RNAs were identified, and quantitative real-time polymerase chain reaction was used to validate 6 filtered long noncoding RNAs. Gene Ontology and KEGG pathway analyses identified several remarkably biological processes and signaling pathways, including spliceosome, RNA transport, and ubiquitin-mediated proteolysis. The transcriptional factors MYC, GABPA, and E2F1 were found to play a central function in the long noncoding RNAs process, as indicated by the coexpression network. This study revealed the dysregulated long noncoding RNA profiles of mucosal gastric cancer. The results shed light on the biological function of long noncoding RNAs in gastric cancer pathogenesis. This provides useful information for exploring potential early screening biomarkers in gastric cancer.

Long Non-Coding RNA AC118344.1 Promotes Gastric Cancer Cell Proliferation, Invasion, and Metastasis via AKT2 and Its Downstream Molecules HK2 and MMP2

Background

Gastric cancer (GC) is a highly occurring cancer with poor prognosis. Reports indicate that long non-coding RNA (LncRNA) potentially regulates tumor progression. Herein, we aim to explore the effect of LncRNA AC118344.1 on the progression of gastric cancer.

Methods

Overexpression and knockout experiments were used to clarify the potential molecular signaling mechanisms induced by AC118344.1. CCK-8, transwell and in vivo metastasis assay were used to detect the function of AC118344.1 in AGS and SGC-7901 cells. Additionally, shRNA silencing techniques, qRT-PCR and Western blot assay were used to explore the relationship between AC118344.1, AKT2, and its downstream molecules.

Results

Upregulating the expression of AC118344.1 induces cell proliferation, invasion in vitro, and lung metastasis in vivo whereas downregulating the expression of AC118344.1 inhibits these effects. Besides, silencing the expression of AC118344.1 downregulated the expression of AKT2 in both the two cells. On the other hand, silencing the expression of AKT2 by shRNA was unable to downregulate the expression of AC118344.1 in both the gastric cancer cells. Also, AC118344.1 regulated AKT2 via its downstream molecules including HK2 and MMP2.

Conclusion

AC118344.1 promotes gastric cancer cell proliferation and invasion and lung metastasis in nude mice by upregulating the expression of AKT2 and its downstream molecules (HK2 and MMP2). Therefore, our findings provide a novel mechanism of the AC118344.1-AKT2-HK2/MMP2 axis in regulating the development of gastric cancer cells.

MicroRNA-99 family in cancer and immunity

The microRNA (miR)-99 family comprising miR-99a, miR-99b, and miR-100 is an evolutionarily conserved family with existence dating prior to the bilaterians. Members are typically oncogenic in leukemia while their functional roles in other cancers alternate between that of a tumor suppressor and a tumor promoter. Targets of the miR-99 family rank in the lists of oncogenes and tumor suppressors, thereby illustrating the dual role of this miR family as oncogenic miRs (oncomiRs) and tumor suppressing miRs (TSmiRs) in different cellular contexts. In addition to their functional roles in cancers, miR-99 family is implicated in the modulation of macrophage inflammatory responses and T-cell subsets biology, thereby exerting critical roles in the maintenance of tissue homeostasis, establishment of peripheral tolerance as well as resolution of an inflammatory reaction. Here, we review emerging knowledge of this miR family and discuss remaining concerns linked to their activities. A better dissection of the functional roles of miR-99 family members in cancer and immunity will help in the development of novel miR-99-based therapeutics for the treatment of human cancer and immune-related diseases. This article is categorized under: RNA in Disease and Development > RNA in Disease.

HOTAIR contributes to the carcinogenesis of gastric cancer via modulating cellular and exosomal miRNAs level

Gastric cancer (GC) is one of the most leading malignancies. Long noncoding RNA is related to GC. In this study, 11 miRNAs in the exosomes and six lncRNAs in the tissues was examined by qRT-PCR. Correlation analysis was used to analyze the relationship between miRNAs in exosome and lncRNAs in the tissues. Four miRNAs level in GC tissues were examined by qRT-PCR. MTT was used to determine cell viability. Flow cytometry was used to quantify the apoptotic cells. Transwell assay was used to examine the migration and invasion capacity. Dual-luciferase assay was used to examine the interaction between HOTAIR and miR-30a or -b. Capillary formation was used to determine the capillary formation capacity. Weak negative correlations were found between HOTAIR and miR-30a or -b in GC tissue samples. Interestingly, strong negative correlations were identified between the HOTAIR level in GC tissue samples and the miR-30a or -b levels in plasma exosomes. HOTAIR knockdown GC cells exhibited decreased migration, invasion, proliferation, and upregulated apoptosis, which released more miR-30a and -b into the exosomes. KRAS was upregulated when co-cultured with exosomes from HOTAIR overexpressed cells, and promoted GC cells proliferation, migration, and invasion. Meanwhile, HUVEC cells expressed increased VEGF-A and formatted more capillaries. Subsequently, we identified a 10mer target site of miR-30a or -b in HOTAIR sequence, and the overexpression of HOTAIR induced the degradation of miR-30a or -b, indicating a ceRNA role of HOTAIR. We report the negative correlation between the plasma miRNAs level and GC tissue HOTAIR expression for the first time and unveiled the ceRNA role of HOTAIR in GC. HOTAIR functions as an onco-lncRNA regulating the level of miR-30a and -b in both GC cells and exosomes. These findings may give insight into understanding the mechanism of GC pathogenesis and provide new biomarkers for clinical diagnosis.

Helicobacter pylori Eradication Can Reverse the Methylation-Associated Regulation of miR-200a/b in Gastric Carcinogenesis

Background/Aims

Epigenetic change is one of the mechanisms that regulates the expression of microRNAs (miRNAs) and is known to play a role in Helicobacter pylori-associated gastric carcinogenesis. We aimed to evaluate the epigenetic changes of miR-200a/b in H. pylori-associated gastric carcinogenesis and restoration after eradication.

Methods

The expression and methylation levels of miR-200a/b were evaluated in gastric cancer (GC) cell lines, human gastric mucosa of H. pylori-negative and -positive controls, and H. pylori-positive GC patients. Next, the changes in the expression and methylation levels of miR-200a/b were compared between H. pylori-eradication and H. pylori-persistence groups at 6 months. Real-time reverse transcription-polymerase chain reaction was conducted to investigate the miRNA expression levels, and MethyLight was performed to assess the methylation levels.

Results

In the GC cell lines, the level of miR-200a/b methylation decreased and the level of expression increased after demethylation. In the human gastric mucosa, the miR-200a/b methylation levels increased in the following group order: H. pylori-negative control group, H. pylori-positive control group, and H. pylori-positive GC group. Conversely, the miR-200a/b expression levels decreased in the same order. In the H. pylori-persistence group, no significant changes were observed in the methylation and expression levels of miR-200a/b after 6 months, whereas the level of methylation decreased and the level of expression of miR-200a/b increased significantly 6 months in the H. pylori-eradication group.

Conclusions

Epigenetic alterations of miR-200a/b may be implicated in H. pylori-induced gastric carcinogenesis. This field defect for cancerization is suggested to be improved by H. pylori eradication.

The functional role of long noncoding RNA in resistance to anticancer treatment

Chemotherapy is one of the fundamental methods of cancer treatment. However, drug resistance remains the main cause of clinical treatment failure. We comprehensively review the newly identified roles of long noncoding RNAs (lncRNAs) in oncobiology that are associated with drug resistance. The expression of lncRNAs is tissue-specific and often dysregulated in human cancers. Accumulating evidence suggests that lncRNAs are involved in chemoresistance of cancer cells. The main lncRNA-driven mechanisms of chemoresistance include regulation of drug efflux, DNA damage repair, cell cycle, apoptosis, epithelial-mesenchymal transition (EMT), induction of signaling pathways, and angiogenesis. LncRNA-driven mechanisms of resistance to various antineoplastic agents have been studied extensively. There are unique mechanisms of resistance against different types of drugs, and each mechanism may have more than one contributing factor. We summarize the emerging strategies that can be used to overcome the technical challenges in studying and addressing lncRNA-mediated drug resistance.

Combined eight-long noncoding RNA signature: a new risk score predicting prognosis in elderly non-small cell lung cancer patients

The elderly are the majority of patients with non-small cell lung cancer (NSCLC). Compared to the overall population's predictive guidance, an effective predictive guidance for elderly patients can better guide patients' postoperative treatment and improve overall survival (OS) and disease-free survival (DFS). Recently, the long non-coding RNAs (lncRNAs) have been found to play an important role in predicting tumor prognosis. To identify potential lncRNAs to predict survival in elderly patients with NSCLC, in the present study, we chose 456 elderly patients with NSCLC and analyzed differentially expressed lncRNAs from four Gene Expression Omnibus (GEO) datasets (GSE30219, GSE31546, GSE37745 and GSE50081). We then constructed an eight-lncRNA formula to predict elderly patients’ prognosis in NSCLC. Furthermore, we validated the prognostic values of the new risk model in two independent datasets, TCGA (n=670) and GSE31210 (n=130). Our data suggested a significant association between risk model and patients’ prognosis. Finally, stratification analysis further revealed the eight-lncRNA signature was an independent factor to predict OS and DFS in stage I elderly patients from both the discovery and validation groups. Functional prediction revealed that 8 lncRNAs have potential effects on tumor immune processes such as lymphocyte activation and TNF production in NSCLC. In summary, our data provides evidence that the eight-lncRNA signature could serve as an independent biomarker to predict prognosis in elderly patients with NSCLC especially in elderly stage I patients.

FLAD1 is up-regulated in Gastric Cancer and is a potential prediction of prognosis

Background: Gastric cancer (GC) is a common malignancy throughout the world. Biomarkers for prognosis and risk evaluation of GC are rapidly discovered. We investigated the prognostic role of FLAD1, an important protein-coding gene that affects cell cycle and survival. Methods: The expression of FLAD1 at mRNA levels in GC tumor tissues and normal tissues was mined and analyzed in Oncomine database and verified in 10 pairs of GS tissues and their adjacent normal tissues in our center by RT qPCR. The FLAD1 protein expression were detected in 106 paraffin-embedded GC tissues by immunohistochemistry (IHC). Statistical analyses were applied to evaluate the clinical significance of FLAD1. The prognostic value of FLAD1 mRNA expression was also analyzed using the Kaplan-Meier plotter (www.kmplot.com). Results: Statistics obtained from online database suggested FLAD1 mRNA was overexpressed in GC tissues. The results were further validated in 10 pairs of GS tissues and adjacent normal tissues in our center (p=0.021). IHC and survival analysis of GC samples from 106 patients showed FLAD1 was overexpressed in 63/106 (59.4%) patients and was associated to higher TNM stage (p=0.026). Multivariate analysis revealed FLAD1 was an independent prognostic factor for GC (p < 0.001). Furthermore, FLAD1 mRNA was associated to unfavorable overall survival (OS), first progression (FP), and post-progression survival (PPS) of GC (p<0.001). Conclusion: FLAD1 in GC is overexpressed at both mRNA and protein level and could be a potential biomarker for GC prognosis.

Quantitative Proteomics Analysis Revealed the Potential Role of lncRNA Ftx in Promoting Gastric Cancer Progression

PURPOSE

The molecular pathogenesis of gastric cancer is still ambiguous till now. Here, it is demonstrated that long noncoding RNA (lncRNA) Ftx acts as a novel tumor promotor of gastric cancer and a potent regulator of hexokinase-2 (HK2).

EXPERIMENTAL DESIGN

The role of lncRNA Ftx is detected in the loss and gain-of-function models of gastric cancer cells. Tandem mass tags combined with multidimensional LC and MS analyses are performed to decipher comparative proteomic profiles of gastric cancer cells in response to lncRNA Ftx knockdown and overexpression. Real-time roteomics-clinical applications (PCR) and western blot are used to validate the proteomic data.

RESULTS

A total of 5124 proteins are quantified and indicated in diverse biological functions and metabolic related signaling pathways. Interestingly, HK2, which is downregulated when lncRNA Ftx is deleted and upregulated while lncRNA Ftx is overexpressed, is further validated in gastric cancer cells.

CONCLUSIONS AND CLINICAL RELEVANCE

The present study suggests lncRNA Ftx promotes gastric cancer progression by upregulating HK2, which provides a new perspective for the mechanism of gastric cancer progression, and thus identifies potential therapeutic targets for gastric cancer.

Long noncoding RNA VCAN-AS1 contributes to the progression of gastric cancer via regulating p53 expression

Gastric cancer (GC) is one of the most frequent malignancies worldwide. Long noncoding RNAs (lncRNAs) are found to be largely implicated in various cancers, including GC. However, the function of lncRNA VCAN antisense RNA 1 (VCAN-AS1) in GC remains unclear. Herein, we observed a low level of VCAN-AS1 in normal gastric tissues through NCBI and UCSC, and that VCAN-AS1 upregulation in GC tissues was related to poor prognosis by TCGA. Furthermore, VCAN-AS1 was found markedly enhanced in GC tissues and cell lines, while its upregulation was related with clinical outcomes of GC patients. Besides this, silencing VCAN-AS1 represses cell proliferation, migration, and invasion but enhances apoptosis. More important, we discovered that VCAN-AS1 expression was negatively correlated with wild-type p53 levels in GC tissues and that p53 was negatively modulated by VCAN-AS1 in GC cells. Furthermore, p53 suppression reversed the repression of VCAN-AS1 silence on the biological processes of AGS cells. Intriguingly, we identified that both VCAN-AS1 and TP53 can bind with eIF4A3, one of the core proteins in the exon junction complex. Also, we confirmed that VCAN-AS1 negatively regulates TP53 expression by competitively binding with eIF4A3. Our findings disclosed that VCAN-AS1 contributes to GC progression through interacting with eIF4A3 to downregulate TP53 expression, indicating that VCAN-AS1 is a novel therapeutic strategy for GC treatment.

LncRNAs as potential diagnostic and prognostic biomarkers in gastric cancer: A novel approach to personalized medicine

Gastric cancer is the third leading cause of cancer death with 5-year survival rate of about 30-35%. Since early detection is associated with decreased mortality, identification of novel biomarkers for early diagnosis and proper management of patients with the best response to therapy is urgently needed. Long noncoding RNAs (lncRNAs) due to their high specificity, easy accessibility in a noninvasive manner, as well as their aberrant expression under different pathological and physiological conditions, have received a great attention as potential diagnostic, prognostic, or predictive biomarkers. They may also serve as targets for treating gastric cancer. In this review, we highlighted the role of lncRNAs as tumor suppressors or oncogenes that make them potential biomarkers for the diagnosis and prognosis of gastric cancer. Relatively, lncRNAs such as H19, HOTAIR, UCA1, PVT1, tissue differentiation-inducing nonprotein coding, and LINC00152 could be potential diagnostic and prognostic markers in patients with gastric cancer. Also, the impact of lncRNAs such as ecCEBPA, MLK7-AS1, TUG1, HOXA11-AS, GAPLINC, LEIGC, multidrug resistance-related and upregulated lncRNA, PVT1 on gastric cancer epigenetic and drug resistance as well as their potential as therapeutic targets for personalized medicine was discussed.

Long non-coding RNA LINC00152 promotes tumorigenesis via sponging miR-193b-3p in osteosarcoma

The majority of the human genome has been revealed to be non-protein-coding, which are transcribed into noncoding RNAs (ncRNA), RNAs which are not translated into protein. Long non-coding RNAs (lncRNAs), including LINC00152, may be associated with the pathogenesis of different types of cancer. LINC00152 serves as an endogenous sponge by binding to micro-RNAs (miRNAs) and inhibiting their activity. The current study revealed that LINC00152 is overexpressed in osteosarcoma cells, leading to increased cell proliferation, and decreased G0/G1 cell cycle arrest and apoptosis. The binding of miR-193b-3p to LINC00152 was demonstrated by dual-luciferase assay, and led to miR-193b-3p downregulation in osteosarcoma cells. Knockdown of LINC00152 revealed an antitumorigenic effect by reducing cell proliferation and increasing G0/G1 arrest and apoptosis. Inhibiting miR-193b-3p reversed the effects of LINC00152 knockdown. These results suggested that LINC00152 binds to miR-193b-3p and reduces its expression level, leading to increased cell proliferation and decreased G0/G1 cell cycle arrest and apoptosis in osteosarcoma cells.

Incorporating molecular biomarkers into clinical practice for gastric cancer

Introduction: Gastric cancer is one of the most common causes of cancer-related mortality worldwide. To improve clinical outcomes, it is critical to develop appropriate approaches to diagnosis and treatment. Biomarkers have numerous potential clinical applications, including screening, assessing risk, determining prognosis, monitoring recurrence, and predicting response to treatment. Furthermore, biomarkers may contribute to the development of effective therapies. Areas covered: Here we review recent progress in exploiting GC-specific biomarkers such as protein-coding genes, microRNAs, long noncoding RNAs, and methylated gene promoters. Expert opinion: The development of biomarkers for diagnosing and monitoring gastric cancer and for individualizing therapeutic targets shows great promise for improving gastric cancer management.

Induction/reversal of drug resistance in gastric cancer by non-coding RNAs (Review)

Gastric cancer (GC) is one of the most prevalent and malignant types of cancer worldwide. In China, it is the second most common type of cancer and the malignancy with the highest incidence and mortality rate. Chemotherapy for GC is not always effective due to the development of drug resistance. Drug resistance, which is frequently observed in GC, undermines the success rate of chemotherapy and the survival of patients with GC. The dysregulation of non‑coding RNAs (ncRNAs), primarily microRNAs (miRNAs or miRs) and long non‑coding RNAs (lncRNAs), is involved in the development of GC drug resistance via numerous mechanisms. These mechanisms contribute to the involvement of a large and complex network of ncRNAs in drug resistance. In this review, we focus on and summarize the latest research on the specific mechanisms of action of miRNAs and lncRNAs that modulate drug resistance in GC. In addition, we discuss future prospects and clinical applications of ncRNAs as potential targeted therapies against the chemoresistance of GC.

Reciprocal regulations between miRNAs and HIF-1α in human cancers

Hypoxia inducible factor-1α (HIF-1α) is a central molecule involved in mediating cellular processes. Alterations of HIF-1α and hypoxically regulated microRNAs (miRNAs) are correlated with patients' outcome in various cancers, indicating their crucial roles on cancer development. Recently, an increasing number of studies have revealed the intricate regulations between miRNAs and HIF-1α in modulating a wide variety of processes, including proliferation, metastasis, apoptosis, and drug resistance, etc. miRNAs are a class of small noncoding RNAs which function as negative regulators by directly targeting mRNAs. Evidence shows that miRNAs can be regulated by HIF-1α at transcriptional level. In turn, HIF-1α itself can be modulated by many miRNAs whose alterations have been implicated in tumorigenesis, thus forming a reciprocal regulation network. These findings add a new layer of complexity to our understanding of HIF-1α regulatory networks. Here, we will provide a comprehensive overview of the current advances about the bidirectional interactions between HIF-1α and miRNAs in human cancers. Besides, the review will summarize the roles of miRNAs/HIF-1α crosstalk according to various cellular processes. Finally, the potential values of miRNAs/HIF-1α loops in clinical applications are discussed.

Knockdown of linc00152 inhibits the progression of gastric cancer by regulating microRNA-193b-3p/ETS1 axis

BACKGROUND

Gastric cancer (GC) is a serious threat for public health worldwide. Long non-coding RNA (lncRNA) linc00152 has been well reported to be an oncogene and a potential biomarker in multiple cancers including GC. However, the molecular mechanisms of linc00152 in GC development need to be further investigated.

METHODS

RT-qPCR assay was employed to detect the levels of linc00152, microRNA-193b-3p (miR-193b-3p) and ETS1 mRNA. ETS1 protein level was measured by western blot assay. Cell proliferative, migratory and invasive capacities were assessed by colony formation together with CCK-8 assays, transwell migration and invasion assays, respectively. Bioinformatics analyses and luciferase reporter assay were used to explore whether miR-193b-3p could interact with linc00152 or ETS1 3'UTR. The roles and molecular basis of linc00152 silence on the growth of GC xenograft tumors were tested in vivo.

RESULTS

Linc00152 expression was notably upregulated in GC tissues and cells. The proliferative, migratory and invasive abilities of GC cells were weakened by linc00152 depletion, miR-193b-3p overexpression or ETS1 knockdown. Linc00152 upregulation inhibited miR-193b-3p expression by direct interaction and abolished miR-193b-3p-mediated anti-proliferation, anti-migration and anti-invasion effects in GC cells. ETS1 was a target of miR-193b-3p and linc00152 could promote ETS1 expression by downregulating miR-193b-3p. In vivo experiments further validated that linc00152 knockdown inhibited the growth of GC xenograft tumors by upregulating miR-193b-3p and downregulating ETS1.

CONCLUSION

Knockdown of linc00152 inhibited GC progression by sequestering miR-193b-3p from ETS1 in vitro and in vivo, elucidating a novel molecular mechanism of linc00152 in promoting GC carcinogenesis.

Long non-coding RNA MIF-AS1 promotes gastric cancer cell proliferation and reduces apoptosis to upregulate NDUFA4

Long non‐coding RNA MIF‐AS1 (lncMIF‐AS1) has been found to be upregulated in the tumor tissues of gastric cancer; however, its importance for the progression of gastric cancer remains unknown. Thus, the present study was designed to determine the role of the lncMIF‐AS1‐based signal transduction pathway in mediating the proliferation and apoptosis of gastric cancer cells. Differentially expressed lncRNAs and mRNAs were screened out using microarray analysis, based on the published data (GSE63288), and validated using quantitative RT‐PCR. Target relationships between lncRNA‐micro RNA (miRNA) and miRNA‐mRNA were predicted by bioinformatics analysis and verified by dual‐luciferase reporter assay. Protein expression of NDUFA4, COX6C and COX5B was detected by western blot. Cell proliferation, cell cycle and apoptosis were determined using colony formation assay and flow cytometry analysis. Oxidative phosphorylation in gastric cancer cells was assessed by levels of oxygen consumption and ATP synthase activity. Expression of lncMIF‐AS1 and NDUFA4 were upregulated in gastric cancer tissues and cells as compared with non‐cancerous gastric tissues and cells (P < .05). MiR‐212‐5p was identified as the most important miRNA linker between lncMIF‐AS1 and NDUFA4, which was negatively regulated by lncMIF‐AS1 and its depletion is the main cause of NDUFA4 overexpression (P < .01). The upregulated expression of NDUFA4 then greatly promoted the proliferation and decreased the apoptosis of gastric cancer cells through activation of the oxidative phosphorylation pathway. Taken together, the present study implies that inhibition of lncMIF‐AS1/miR‐212‐5p/NDUFA4 signal transduction may provide a promising therapeutic target for the treatment of gastric cancer.

Prader-Willi region non-protein coding RNA 1 suppressed gastric cancer growth as a competing endogenous RNA of miR-425-5p

Gastric cancer (GC) is one of the major global health problems, especially in Asia. Nowadays, long non-coding RNA (lncRNA) has gained significant attention in the current research climate such as carcinogenesis. This research desires to explore the mechanism of Prader-Willi region non-protein coding RNA 1 (PWRN1) on regulating GC process. Differentially expressed lncRNAs in GC tissues were screened out through microarray analysis. The RNA and protein expression level were detected by quantitative real-time PCR (qRT-PCR) and Western blot. Cell proliferation, apoptosis rate, metastasis abilities were respectively determined by cell counting kit 8 (CCK8), flow cytometry, wound healing, and transwell assay. The luciferase reporter system was used to verify the targetting relationships between PWRN1, miR-425-5p, and phosphatase and tensin homolog (PTEN). RNA-binding protein immunoprecipitation (RIP) assay was performed to prove whether PWRN1 acted as a competitive endogenous RNA (ceRNA) of miR-425-5p Tumor xenograft model and immunohistochemistry (IHC) were developed to study the influence of PWRN1 on tumor growth in vivo Microarray analysis determined that PWRN1 was differently expressed between GC tissues and adjacent tissues. qRT-PCR revealed PWRN1 low expression in GC tissues and cells. Up-regulated PWRN1 could reduce proliferation and metastasis and increase apoptosis in GC cells, while miR-425-5p had reverse effects. The RIP assay indicated that PWRN1 may target an oncogene, miR-425-5p The tumor xenograft assay found that up-regulated PWRN1 suppressed the tumor growth. The bioinformatics analysis, luciferase assay, and Western blot indicated that PWRN1 affected PTEN/Akt/MDM2/p53 axis via suppressing miR-425-5p Our findings suggested that PWRN1 functioned as a ceRNA targetting miR-425-5p and suppressed GC development via p53 signaling pathway.

Oncogenic role of miR‑183‑5p in lung adenocarcinoma: A comprehensive study of qPCR, in vitro experiments and bioinformatic analysis

Despite the fact that previous studies have reported the aberrant expression of miR-183-5p in lung adenocarcinoma (LUAD), the oncogenic role of miR-183-5p in LUAD and its underlying mechanisms have remained elusive. Hence, we attempted to elucidate the clinicopathological significance of miR-183-5p expression in LUAD and identify the biological function of miR-183-5p in LUAD in this study. Meta-analysis of Gene Expression Omnibus (GEO) data, data mining of The Cancer Genome Atlas (TCGA) and real-time quantitative polymerase chain reaction (qPCR) were performed to evaluate the clinicopathological significance of miR-183-5p in LUAD. Then, the effect of miR-183-5p on cell growth in LUAD was assessed by in vitro experiments. Additionally, the target genes of miR-183-5p were identified via miRWalk v.2.0 and TCGA. Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis and Disease Ontology (DO) analysis were further carried out for the target genes. The targetability between target genes in key KEGG pathways and miR-183-5p was validated by independent samples t-test, Pearson's correlation test and immunohistochemistry results from the Human Protein Atlas (HPA). According to the results, miR-183-5p was overexpressed in LUAD and exhibited significant diagnostic value. Moreover, miR-183 expression was associated with tumor progression in the TCGA data. In vitro experiments revealed the positive influence of miR-183-5p on cell viability and proliferation as well as the negative effect of miR-183-5p on caspase-3/7 activity in LUAD, which supports the finding that target genes of miR-183-5p are mainly enriched in gene pathways containing cell adhesion molecules (CAMs) and gene pathways important in cancer. Therefore, we conclude that miR-183-5p acts as an oncogene in LUAD and participates in the pathogenesis of LUAD via the interaction networks of its target genes.

Epigenetic Mechanisms and Events in Gastric Cancer-Emerging Novel Biomarkers

Gastric cancer is one of the most common malignancy worldwide. The various genetic and epigenetic events have been found to be associated with its carcinogenesis. The epigenetic is a heritable and transient/reversible change in the gene expression that is not accompanied by modification in the DNA sequence. This event is characterized by the alteration in the promoter CpG island of the gene or histone modification. These events are associated with silencing of critical tumor suppressor gene and activation of oncogenes leading to carcinogenesis. The DNA methylation is a chemical change in the DNA sequence that most commonly occurs at cytosine moiety of CpG dinucleotide and histone, primarily on N- terminal tail that ultimately effect the interaction of DNA with chromatin modifying protein.Hypermethylation of tumor suppressor genes and global hypomethylation of oncogenes are widely studied epigenetic modifications. There are large number of publish reports regarding epigenetic events involving gastric cancer. These changes are potentially useful in identifying markers for early diagnosis and management of this lethal malignancy. Also, role of specific miRNAs and long non coding RNAs in regulation of gene expression is gaining interest and is a matter of further investigation. In this review, we aimed to summarize major epigenetic events (DNA methylation) in gastric cancer along with alteration in miRNAs and long non coding RNAs which plays an important role in pathology of this poorly understood malignancy.

MiR-217 is involved in the carcinogenesis of gastric cancer by down-regulating CDH1 expression

GC is one of the most leading malignancies all over the world, and is also the leading cause of cancer-related mortalities. At present, GC remains difficult to diagnose at an early stage. In this study, we first detected the expression of 9 selected miRNAs in the exosomes from 67 GC patients' circular exosomes and found 4 miRNAs level was significantly altered. Meanwhile, one out of 4 candidate miRNAs also had a higher expression in the GC tissue samples, and negative correlated with CDH1 expression. Predicted by bioinformatics tools, confirmed by dual luciferase assay and immunoblotting, we identified that CDH1 is a direct target of miR-217. MiR-217 overexpression enhanced gastric cancer cells proliferation, and reduced exosomal CDH1 level which can be delivered into microenvironment. In conclusion, we constructed the negative correlation between miR-217 and CDH1 level in GC patients and cells; unveiled part of the miR-217 function during the pathogenesis of GC. These findings may give insight into understanding the mechanism of GC pathogenesis and provide new biomarkers for clinical diagnosis.

Evaluation of the expression and clinical value of lncRNA AC010761.9 in human gastric adenocarcinoma

Background

The current study determined the expression and clinical value of lncRNA AC010761.9 in human gastric adenocarcinoma (GA).

Methods

Real-time quantitative reverse transcription (qRT)-PCR was used to detect the level of lncRNA expression in 145 GA tissues and three GA cell lines, and the correlation between its level and clinicopathologic characteristics and potential corresponding mRNA of TNF receptor-associated factor 4 gene (TRAF4) was then evaluated.

Results

Elevated lncRNA AC010761.9 was detected in all 6 GA tissues by previous lncRNA expression profile microarray assay. LncRNA AC010761.9 was over-expressed in 99 of 145 GA tissues (68.3%) with an elevated fold change of up to 35.14 compared to matched paracancerous tissues (p < 0.05), and was also over-expressed in the 3 GA cell lines (MGC803, BGC823, and SGC7901) compared to the normal gastric mucosal epithelial cell line (GES-1 cells; p < 0.05) by qRT-PCR. The elevated expression of this lncRNA was related to tumor size (p = 0.028), degree of differentiation (p = 0.047), and serum carbohydrate antigen (CA19-9) and carcinoembryonic antigen (CEA) concentrations (p = 0.026 and p = 0.037, respectively). Multivariate analysis further confirmed that the expression of lncRNA AC010761.9 was related to the degree of tumor differentiation (p = 0.015). Additionally, the expression of lncRNA AC010761.9 had a positive correlation with the mRNA expression of the potentially associated gene (TRAF4) in GA tissues (r = 0.385, p < 0.01).

Conclusions

LncRNA AC010761.9 may be linked to GA progression and is a potential new biomarker for GA.

Electronic supplementary material

The online version of this article (10.1186/s12957-017-1289-y) contains supplementary material, which is available to authorized users.

Ultraconserved element uc.372 drives hepatic lipid accumulation by suppressing miR-195/miR4668 maturation

Ultraconserved (uc) RNAs, a class of long non-coding RNAs (lncRNAs), are conserved across humans, mice, and rats, but the physiological significance and pathological role of ucRNAs is largely unknown. Here we show that uc.372 is upregulated in the livers of db/db mice, HFD-fed mice, and NAFLD patients. Gain-of-function and loss-of-function studies indicate that uc.372 drives hepatic lipid accumulation in mice by promoting lipogenesis. We further demonstrate that uc.372 binds to pri-miR-195/pri-miR-4668 and suppresses maturation of miR-195/miR-4668 to regulate expression of genes related to lipid synthesis and uptake, including ACC, FAS, SCD1, and CD36. Finally, we identify that uc.372 is located downstream of the insulinoma-associated 2 (INSM2) gene that is transcriptionally activated by upstream transcription factor 1 (USF1). Our findings reveal a novel mechanism by which uc.372 drives hepatic steatosis through inhibition of miR-195/miR-4668 maturation to relieve miR-195/miR-4668-mediated suppression of functional target gene expression.

Ultraconserved RNAs are a class of long non-coding RNAs whose functions are yet to be identified. Here Guo and colleagues show that an ultraconserved RNA uc.372 promotes lipogenesis and lipid accumulation within the hepatocytes by suppressing the maturation of miR-195/miR-4668 that inhibits lipogenic gene expression.

Pseudogene BMI1P1 expression as a novel predictor for acute myeloid leukemia development and prognosis

The BMI1P1 levels of 144 de novo AML patients and 36 healthy donors were detected by real-time quantitative PCR (RQ-PCR). BMI1P1 was significantly down-regulated in AML compared with control (P < 0.001). A receiver operating characteristic (ROC) curve revealed that BMI1P1 expression could differentiate patients with AML from control subjects (AUC = 0.895, 95% CI: 0.835–0.954, P < 0.001). The percentage of blasts in bone marrow (BM) was significantly lower in BMI1P1 high-expressed group versus low-expressed group (P = 0.008). BMI1P1 high-expressed cases had significantly higher complete remission (CR) than BMI1P1 low-expressed cases (P = 0.023). Furthermore, Kaplan–Meier demonstrated that both whole AML cohort and non-M3-AML patients with low BMI1P1 expression showed shorter leukemia free survival (LFS, P = 0.002 and P = 0.01, respectively) and overall survival (OS, P < 0.001 and P = 0.011, respectively) than those with high BMI1P1 expression. Multivariate analysis also showed that BMI1P1 over-expression was an independent favorable prognostic factor for OS in both whole and non-M3 cohort of AML patients (HR = 0.462, 95% CI = 0.243–0.879, P = 0.019 and HR = 0.483, 95% CI = 0.254–0.919, P = 0.027). To further investigate the significance of BMI1P1 expression in the follow-up of AML patients, we monitored the BMI1P1 level in 26 de novo AML patients and found that the BMI1P1 level increased significantly from the initial diagnosis to post-CR (P < 0.001). These results indicated that BMI1P1 might contribute to the diagnosis of AML and the assessment of therapeutic effect.

Identification of key miRNAs and genes associated with stomach adenocarcinoma from The Cancer Genome Atlas database

Stomach adenocarcinoma (STAD) is the second leading cause of cancer death and a fuller understanding of its molecular basis is needed to develop new therapeutic targets. miRNA and mRNA data were downloaded from The Cancer Genome Atlas database, and the differentially expressed miRNAs and genes were identified. The target genes of differentially expressed miRNAs were screened by prediction tools. Furthermore, the biological function of these target genes was investigated. Several key miRNAs and their target genes were selected for validation using quantitative real-time polymerase chain reaction (qRT-PCR). The Gene Expression Omnibus (GEO) dataset was used to verify the expression of selected miRNAs and target genes. The diagnostic value of identified miRNAs and genes was accessed by receiver operating characteristic analysis. A total of 1248 differentially expressed genes were identified in STAD. Additionally, nine differentially expressed miRNAs were identified and 160 target genes of these nine miRNAs were identified via target gene detection. Interestingly, they were remarkably enriched in the calcium signaling pathway and bile secretion. qRT-PCR confirmed the expression of several key miRNAs and their target genes. The expression levels of hsa-miR-145-3p, hsa-miR-145-5p, ADAM12,ACAN,HOXC11 and MMP11 in the GEO database were compatible with the bioinformatics results. hsa-miR-139-5p, hsa-miR-145-3p and MMP11 have a potential diagnostic value for STAD. Differential expression of the mature form of miRNAs (hsa-miR-139-5p, hsa-miR-145-3p, hsa-miR-145-5p and hsa-miR-490-3p) and genes including ADAM12,ACAN,HOXC11 and MMP11 and calcium and bile secretion signaling pathways may play important roles in the development of STAD.

miR-106b promotes cell invasion and metastasis via PTEN mediated EMT in ESCC

MicroRNA (miR)-106b serves an essential function in a variety of human cancer types, particularly in the process of invasion and metastasis. However, the function and mechanism of miR-106b in the invasion and metastasis of esophageal squamous cell carcinoma (ESCC) has remained elusive. In the present study, it was demonstrated that miR-106b was upregulated in ESCC tissues and cell lines. Furthermore, miR-106b expression in ESCC tissues was positively associated with lymphatic metastasis. Inhibition of miR-106b in EC-1 and EC9706 cells decreased not only the invasion and metastasis ability but also the proliferation ability of EC-1 and EC9706 cells. In addition, miR-106b had the ability to induce epithelial-to-mesenchymal transition (EMT) in EC-1 and EC9706 cells. In terms of the underlying mechanism, it was revealed that miR-106b promoted the invasion, metastasis and proliferation ability of EC-1 and EC9706 cells by directly targeting phosphatase and tension homolog (PTEN). Furthermore, miR-106b induced EMT in EC-1 and EC9706 cells by suppressing the expression of PTEN. In summary, the present study revealed that miR-106b contributed to invasion and metastasis in ESCC by regulating PTEN mediated EMT. Downregulation of miR-106b may be a novel strategy for preventing tumor invasion and metastasis.

Assessing the Off-Target Effects of miRNA Inhibitors on Innate Immune Toll-Like Receptors

MicroRNAs (miRNAs) are involved in most cellular processes and are deregulated in several diseases. Antisense miRNA oligonucleotides (AMOs) therefore present novel therapeutic opportunities. Currently, in vivo delivery of AMOs often relies on high doses of nucleic acids, with nonspecific uptake by most tissues. Critically, AMOs accumulate in phagocytic cells where they can interfere with immune functions, such as the activation of Toll-Like Receptors (TLRs). In this chapter, we describe a method to assess the possible off-target effects of AMOs on TLR7, 8, and 9 sensing.

FPHPB inhibits gastric tumor cell proliferation by inducing G2-M cell cycle arrest

Gastric cancer is a common cancer in the world with high morbidity and mortality. Here, we report that FPHPB (4-(4-(2-fluoropyridin-3-yl)phenyl)-N-(4-hydroxyphenyl)), a derivative of CMPD-1/MK2a Inhibitor, had anti-tumor activities by inhibiting gastric tumor SNU-16 and SGC7901 cells. FPHPB dose-dependently inhibited cell proliferation, induced cell apoptosis and arrested SNU-16 and SGC7901 cells in G2-M cell cycle checkpoint. Upon treatment with FPHPB, apoptotic proteins cleaved PARP and cleaved caspase-3 were remarkably increased, and G2-M regulatory molecules, the phosphorylation of Cdc2 and Chk2, were significantly accentuated. Collectively, FPHPB has anti-tumor activities and may be a potential candidate for treating gastric cancers.

Long noncoding RNA NEAT1 promotes the metastasis of osteosarcoma via interaction with the G9a-DNMT1-Snail complex

Osteosarcoma (OS) is the most common histological form of primary bone cancer. Long noncoding RNA nuclear enriched abundant transcript 1 (NEAT1) functions as an oncogene in some cancers. However, the functional role of NEAT1 in OS metastasis remains elusive. In the present study, we found that NEAT1 expression was significantly increased in OS tissues and cell lines. Overexpression of NEAT1 in OS tissues was correlated with higher clinical stage, distant metastasis and poorer prognosis. Loss- and gain-of-function assays showed that NEAT1 positively regulated metastasis in vitro and in vivo. In addition, ectopic expression of NEAT1 also induced epithelial-mesenchymal transition (EMT). Mechanistic studies revealed that NEAT1 epigenetically suppresses E-cadherin expression through association with G9a-DNMT1-Snail complex. Taken together, our study reveals a critical epigenetic mechanism underlying NEAT1-mediated metastasis.

The Long Non-Coding RNA TP73-AS1 Interacted With miR-142 to Modulate Brain Glioma Growth Through HMGB1/RAGE Pathway

P73 antisense RNA 1T (non-protein coding), also known as TP73-AS1 or PDAM, is a long non-coding RNA which may regulate apoptosis via regulation of p53-dependent anti-apoptotic genes. An abnormal change of TP73-AS1 expression was noticed in cancers. The effects of TP73-AS1 in brain glioma growth and the underlying mechanism remain unclear so far. In the present study, TP73-AS1 was specifically upregulated in brain glioma tissues and cell lines, and was associated with poorer prognosis in patients with glioma. TP73-AS1 knocking down suppressed human brain glioma cell proliferation and invasion in vitro, as well as HMGB1 protein. MiR-142 has been reported to play a pivotal role in cancers; here we observed that TP73-AS1 and miR-142 could negatively regulate each other. Results from luciferase assays suggested that TP73-AS1 might compete with HMGB1 for miR-142 binding. Further, HMGB1/RAGE was involved in TP73-AS1/miR-142 regulation of glioma cell proliferation and invasion. In glioma tissues, TP73-AS1 and HMGB1 expression was up-regulated, whereas miR-142 expression was down-regulated. Data from the present study revealed that TP73-AS1 promoted the brain glioma growth and invasion through acting as a competing endogenous RNA (ceRNA) to promote HMGB1 expression by sponging miR-142. In conclusion, we regarded TP73-AS1 as an oncogenic lncRNA promoting brain glioma proliferation and invasion, and a potential target for human brain glioma treatment. J. Cell. Biochem. 119: 3007-3016, 2018. © 2017 Wiley Periodicals, Inc.

Molecular mechanisms and theranostic potential of miRNAs in drug resistance of gastric cancer

INTRODUCTION

Systemic chemotherapy is a curative approach to inhibit gastric cancer cells proliferation. Despite the great progress in anti-cancer treatment achieved during the last decades, drug resistance and treatment refractoriness still extensively persists. Recently, accumulating studies have highlighted the role of miRNAs in drug resistance of gastric cancers by modulating some drug resistance-related proteins and genes expression. Pre-clinical reports indicate that miRNAs might serve as ideal biomarkers and potential targets, thus holding great promise for developing targeted therapy and personalized treatment for the patients with gastric cancer. Areas covered: This review provide a comprehensive overview of the current advances of miRNAs and molecular mechanisms underlying miRNA-mediated drug resistance in gastric cancer. We particularly focus on the potential values of drug resistance-related miRNAs as biomarkers and novel targets in gastric cancer therapy and envisage the future research developments of these miRNAs and challenges in translating the new findings into clinical applications. Expert opinion: Although the concrete mechanisms of miRNAs in drug resistance of gastric cancer have not been fully clarified, miRNA may be a promising theranostic approach. Further studies are still needed to facilitate the clinical applications of miRNAs in drug resistant gastric cancer.

MicroRNA-335-5p is a potential suppressor of metastasis and invasion in gastric cancer

Background

Multiple aberrant microRNA expression has been reported in gastric cancer. Among them, microRNA-335-5p (miR-335), a microRNA regulated by DNA methylation, has been reported to possess both tumor suppressor and tumor promoter activities.

Results

Herein, we show that miR-335 levels are reduced in gastric cancer and significantly associate with lymph node metastasis, depth of tumor invasion, and ultimately poor patient survival in a cohort of Amerindian/Hispanic patients. In two gastric cancer cell lines AGS and, Hs 746T the exogenous miR-335 decreases migration, invasion, viability, and anchorage-independent cell growth capacities. Performing a PCR array on cells transfected with miR-335, 19 (30.6%) out of 62 genes involved in metastasis and tumor invasion showed decreased transcription levels. Network enrichment analysis narrowed these genes to nine (PLAUR, CDH11, COL4A2, CTGF, CTSK, MMP7, PDGFA, TIMP1, and TIMP2). Elevated levels of PLAUR, a validated target gene, and CDH11 were confirmed in tumors with low expression of miR-335. The 3′UTR of CDH11 was identified to be directly targeted by miR-335. Downregulation of miR-335 was also demonstrated in plasma samples from gastric cancer patients and inversely correlated with DNA methylation of promoter region (Z = 1.96, p = 0.029). DNA methylation, evaluated by methylation-specific PCR assay, was found in plasma from 23 (56.1%) out of 41 gastric cancer patients but in only 9 (30%) out of 30 healthy donors (p = 0.029, Pearson’s correlation). Taken in consideration, our results of the association with depth of invasion, lymph node metastasis, and poor prognosis together with functional assays on cell migration, invasion, and tumorigenicity are in accordance with the downregulation of miR-335 in gastric cancer.

Conclusions

Comprehensive evaluation of metastasis and invasion pathway identified a subset of associated genes and confirmed PLAUR and CDH11, both targets of miR-335, to be overexpressed in gastric cancer tissues. DNA methylation of miR-335 may be a promissory strategy for non-invasive approach to gastric cancer.

Electronic supplementary material

The online version of this article (10.1186/s13148-017-0413-8) contains supplementary material, which is available to authorized users.

Long Non-Coding RNA SPRY4-IT1 Can Predict Poor Prognosis in Digestive System Malignancies: a Meta-Analysis

Recent studies have reported that long non-coding RNA SPRY4 intron transcript 1 (SPRY4-IT1) is abnormally expressed in malignant digestive tumors and associated with prognosis. But its clinical relevance is unclear. Here, we performed a meta-analysis aims to evaluate the prognostic value of SPRY4-IT1 in digestive system malignancies. We systematic search the PubMed, Web of Science, ScienceDirect and Wiley Online Library database to eligible studies. The pooled hazard ratios (HRs) with a 95% confidence interval (95% CI) were calculated to explored the association of lncRNA SPRY4-IT1 with prognosis. Five studies were eligible for analysis, a total of 518 patients were included. Meta-analysis indicated that overexpression of SPRY4-IT1 was associated with poor over survival (OS) (HR = 1.24, 95%CI:0.49-1.98; random-effects model). The clinicopathological parameters analysis further showed that increased expression level of SPRY4-IT1 was positively correlated with lymph node metastasis (HR = 1.45, 95% CI =0.88-2.02; fixed-effects model), TNM stage (HR = 1.24,95% CI = 0.78-1.70; fixed-effects model), and invasion depth (HR = 1.25,95% CI = 0.63-1.88; fixed-effects model). lncRNA SPRY4-IT1 may serve as a potential prognostic marker in malignant digestive tumors.

MicroRNA-27a contributes to the malignant behavior of gastric cancer cells by directly targeting PH domain and leucine-rich repeat protein phosphatase 2

Background

Accumulating evidence indicates that microRNA-27a (miR-27a) is involved in carcinogenesis and tumor progression. However, the exact function and molecular mechanism of miR-27a in gastric cancer remain unclear.

Methods

Quantitative real-time PCR (qRT-PCR) was used to quantify the expression of miR-27a and its target gene. The function of miR-27a in gastric cancer was investigated through in vitro and in vivo assays (MTT assay, colony formation assay, flow cytometry assay, wound healing assay, migration and invasion assay, immunohistochemistry (IHC), immunofluorescence (IF) and Western blot). A luciferase reporter assay was conducted to confirm the target gene of miR-27a.

Results

We found that miR-27a was commonly overexpressed in gastric cancer and high expression of miR-27a was associated with distant metastasis, lymph node metastasis, advanced T stage and advanced clinical stage. Functional assays demonstrated that overexpression of miR-27a in AGS cells accelerated cell proliferation, migration and invasion and suppressed apoptosis. Meanwhile, opposite results were observed in SGC-7901 cells when miR-27a was suppressed. Consistently, down-regulation of miR-27a inhibited the growth and metastasis of engrafted tumors in vivo. Furthermore, we found PH domain and leucine-rich repeat protein phosphatase 2 (PHLPP2) to be a new target of miR-27a, and downregulation of PHLPP2 could rescue the effect of anti-miR-27a in gastric cancer cells. In addition, miR-27a-mediated suppression of PHLPP2 led to stimulation of the AKT/GSK3β pathway.

Conclusions

Our data suggest that miR-27a functions as a crucial oncogenic miRNA in gastric cancer. It can promote proliferation and metastasis of tumor cells by suppressing PHLPP2 and activating the AKT/GSK3β pathway. Therefore, miR-27a is a potential novel therapeutic target in gastric cancer treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-017-0516-2) contains supplementary material, which is available to authorized users.