Long noncoding RNAs in gastric cancer carcinogenesis and metastasis

An innovative pyroptosis-related long-noncoding-RNA signature predicts the prognosis of gastric cancer via affecting immune cell infiltration landscape

Background: Gastric cancer (GC) is a worldwide popular malignant tumor. However, the survival rate of advanced GC remains low. Pyroptosis and long non-coding RNAs (lncRNAs) are important in cancer progression. Thus, we aimed to find out a pyroptosis-related lncRNAs (PRLs) signature and use it to build a practical risk model with the purpose to predict the prognosis of patients with GC. Methods: Univariate Cox regression analysis was used to identify PRLs linked to GC patient's prognosis. Subsequently, to construct a PRLs signature, the least absolute shrinkage and selection operator regression, and multivariate Cox regression analysis were used. Kaplan-Meier analysis, principal component analysis, and receiver operating characteristic curve analysis were performed to assess our novel lncRNA signature. The correlation between risk signature and clinicopathological features was also examined. Finally, the relationship of pyroptosis and immune cells were evaluated through the CIBERSORT tool and single-sample lncRNA set enrichment analysis (ssGSEA). Results: A PRLs signature comprising eight lncRNAs was discerned as a self-determining predictor of prognosis. GC patients were sub-divided into high-risk and low-risk groups via this risk-model. Stratified analysis of different clinical factors also displayed that the PRLs signature was a good prognosis factor. According to the risk score and clinical characteristics, a nomogram was established. Moreover, the difference between the groups is significance in immune cells and immune pathways. Conclusion: This study established an effective prognostic signature consist of eight PRLs in GC, and constructed an efficient nomogram model. Further, the PRLs correlated with immune cells and immune pathways.

Linear and Circular Long Non-Coding RNAs in Acute Lymphoblastic Leukemia: From Pathogenesis to Classification and Treatment

The coding regions account for only a small part of the human genome, and the remaining vast majority of the regions generate large amounts of non-coding RNAs. Although non-coding RNAs do not code for any protein, they are suggested to work as either tumor suppressers or oncogenes through modulating the expression of genes and functions of proteins at transcriptional, posttranscriptional and post-translational levels. Acute Lymphoblastic Leukemia (ALL) originates from malignant transformed B/T-precursor-stage lymphoid progenitors in the bone marrow (BM). The pathogenesis of ALL is closely associated with aberrant genetic alterations that block lymphoid differentiation and drive abnormal cell proliferation as well as survival. While treatment of pediatric ALL represents a major success story in chemotherapy-based elimination of a malignancy, adult ALL remains a devastating disease with relatively poor prognosis. Thus, novel aspects in the pathogenesis and progression of ALL, especially in the adult population, need to be further explored. Accumulating evidence indicated that genetic changes alone are rarely sufficient for development of ALL. Recent advances in cytogenic and sequencing technologies revealed epigenetic alterations including that of non-coding RNAs as cooperating events in ALL etiology and progression. While the role of micro RNAs in ALL has been extensively reviewed, less attention, relatively, has been paid to other non-coding RNAs. Herein, we review the involvement of linear and circular long non-coding RNAs in the etiology, maintenance, and progression of ALL, highlighting the contribution of these non-coding RNAs in ALL classification and diagnosis, risk stratification as well as treatment.

LncRNA DLGAP1-AS2 overexpression associates with gastric tumorigenesis: a promising diagnostic and therapeutic target

BACKGROUND

Aberrant expression of long noncoding RNAs (lncRNAs) is associated with the progression of human cancers, including gastric cancer (GC). The function of lncRNA DLGAP1-AS2, as a promising oncogene, has been identified in several human cancers. Therefore, this study was aimed to explore the association of DLGAP1-AS2 with gastric tumorigenesis, as well.

METHODS AND RESULTS

The expression level of DLGAP1-AS2 was initially pre-evaluated in GC datasets from Gene Expression Omnibus (GEO). Moreover, qRT-PCR experiment was performed on 25 GC and 25 adjacent normal tissue samples. The Cancer Genome Atlas (TCGA) data were also analyzed for further validation. Consistent with data obtained from GEO datasets, qRT-PCR results revealed that DLGAP1-AS2 was significantly (p < 0.0032) upregulated in GC specimens compared to normal samples, which was additionally confirmed using TCGA analysis (p < 0.0001). DLGAP1-AS2 expression level was also correlated with age (p = 0.0008), lymphatic and vascular invasion (p = 0.0415) in internal samples as well as poor survival of GC patients (p = 0.00074) in GEO datasets. Also, Gene Ontology analysis illustrated that DLGAP1-AS2 may be involved in the cellular process, including hippo signaling, regulated by YAP1, as its valid downstream target, in GC samples. Moreover, ROC curve analysis showed the high accuracy of the DLGAP1-AS2 expression pattern as a diagnostic biomarker for GC.

CONCLUSION

Our findings indicated that DLGAP1-AS2 might display oncogenic properties through gastric tumorigenesis and could be suggested as a therapeutic, diagnostic, and prognostic target.

Upregulation of LINC00659 expression predicts a poor prognosis and promotes migration and invasion of gastric cancer cells

Long non-coding RNAs (lncRNAs) serve an important role in the progression of cancer. LINC00659 was recently identified as a novel oncogenic lncRNA involved in colon cancer cell proliferation via modulating the cell cycle. However, the function of LINC00659 in other types of cancer, especially in gastric cancer (GC), remains unknown. In the present study, bioinformatics analysis combined with cell experiments were performed to explore the function of LINC00659 in GC. It was revealed that LINC00659 expression was significantly upregulated in GC tissues and cell lines. Increased levels of LINC00659 were associated with advanced tumor stage and unfavorable prognosis of patients with GC. Additionally, upregulated LINC00659 expression promoted the migration and invasion of GC cells. Further analysis using a bioinformatics method revealed that matrix metalloproteinase 15 and IQ motif-containing GTPase activating protein 3 were potential downstream targets of LINC00659 involved in tumor metastasis, although the precise underlying mechanism requires further exploration.

Long non-coding RNA ASB16-AS1 inhibits proliferation, migration, and invasion of gastric cancer cells by regulating miR-670-3p/ATXN7L3 axis

BACKGROUND

Many long non-coding RNAs (lncRNAs) have been shown to play a role in suppressing or promoting the progression of gastric cancer (GC). However, there are still a large number of lncRNAs whose roles in the progression of GC are still unclear. Therefore, it is still necessary to identify lncRNAs that affect the proliferation, migration, and invasion of GC cells to provide potential targets for the prevention and treatment of GC.

AIM

To investigate the effect of lncRNA ASB16-AS1 on the proliferation, migration, and invasion of GC cells and the underlying mechanism.

METHODS

The expression levels of ASB16-AS1, miR-670-3p, and ATXN7L3 in human gastric mucosal cell line GES-1 and GC cell lines HGC-27, AGS, and NUGC-4 were detected by real-time fluorescent quantitative PCR (RT-qPCR) and Western blot. HGC-27 cells were divided into si-NC, si-ASB16-AS1, miR-NC, miR-670-3p, si-ATXN7L3, si-ASB16-AS1 + anti-miR-NC, si-ASB16 -AS1 + anti-miR-670-3p, si-ASB16-AS1 + pcDNA-NC, and si-ASB16-AS1 + pcDNA-ATXN7L3 groups. Cell counting kit-8 and transwell assay were used to detect cell viability and migration invasion , respectively. Dual luciferase reportor assay, RT-qPCR, and Western blot were used to determine the interaction between ASB16-AS1 and miR-670-3p and between miR-670-3p and ATXN7L3.

RESULTS

ASB16-AS1 and ATXN7L3 were highly expressed in GC cells, while miR-670-3p was lowly expressed (P < 0.05). After inhibiting the expression of ASB16-AS1, overexpressing miR-670-3p, or inhibiting the expression of ATXN7L3, the proliferation, migration, and invasion of HGC-27 cells were significantly reduced (P < 0.05). ASB16-AS1 targets and negatively regulates miR-670-3p expression. MiR-670-3p targets and negatively regulates ATXN7L3 expression. Inhibiting miR-670-3p partially reversed the effects of inhibiting ASB16-AS1 on the proliferation, migration, and invasion of HGC-27 cells (P < 0.05). Overexpressing ATXN7L3 partially reversed the effect of inhibiting ASB16-AS1 on the proliferation, migration, and invasion of HGC-27 cells (P < 0.05).

CONCLUSION

Inhibiting ASB16-AS1 inhibits the proliferation, migration, and invasion of GC cells by regulating the miR-670-3p/ATXN7L3 axis.

Long Noncoding RNASBF2-AS1 Promotes Gastric Cancer Progression via Regulating miR-545/EMS1 Axis

Objective

Long noncoding RNA (LncRNA) SBF2-AS1 was reportedly to function as an oncogene in several types of cancers, such as hepatocellular carcinoma, nonsmall cell lung cancer, glioma, and colorectal cancer. However, the biological roles and regulatory mechanisms of SBF2-AS1 in gastric cancer (GC) are unknown.

Methods

The expression of SBF2-AS1 and miR-545 were examined in GC tissues and cell lines via real-time quantitative PCR. The relationship of SBF2-AS1 with miR-545 was verified via dual-luciferase reporter gene assay and RNA immunoprecipitation. The influences of SBF2-AS1 on cell proliferation, migration, and invasion were determined using cell counting Kit-8 (CCK-8), wound healing, and transwell invasion assays, respectively.

Results

LncRNA SBF2-AS1 expression was upregulated in GC tissues, especially in advanced clinical stage cases. Moreover, increased SBF2-AS1 indicated a poor survival rate. Functionally, the downregulation of SBF2-AS1 by siRNA in GC cells suppressed the proliferation, migration, and invasion. In terms of mechanism, SBF2-AS1 can directly bind to miR-545 and regulate its expression. Moreover, SBF2-AS1 knockdown significantly decreased the expression of EMS1, which was the direct target of miR-545. Importantly, inhibition of miR-545 or overexpression of EMS1 partially reversed SBF2-AS1-depletion-caused suppression on proliferation, migration, and invasion.

Conclusion

These findings elucidated a crucial role of SBF2-AS1 as a miR-545 sponge in GC cells, suggesting that SBF2-AS1 might be a potential target for GC.

Long non-coding RNAs towards precision medicine in gastric cancer: early diagnosis, treatment, and drug resistance

Gastric cancer is a deadly disease and remains the third leading cause of cancer-related death worldwide. The 5-year overall survival rate of patients with early-stage localized gastric cancer is more than 60%, whereas that of patients with distant metastasis is less than 5%. Surgical resection is the best option for early-stage gastric cancer, while chemotherapy is mainly used in the middle and advanced stages of this disease, despite the frequently reported treatment failure due to chemotherapy resistance. Therefore, there is an unmet medical need for identifying new biomarkers for the early diagnosis and proper management of patients, to achieve the best response to treatment. Long non-coding RNAs (lncRNAs) in body fluids have attracted widespread attention as biomarkers for early screening, diagnosis, treatment, prognosis, and responses to drugs due to the high specificity and sensitivity. In the present review, we focus on the clinical potential of lncRNAs as biomarkers in liquid biopsies in the diagnosis and prognosis of gastric cancer. We also comprehensively discuss the roles of lncRNAs and their molecular mechanisms in gastric cancer chemoresistance as well as their potential as therapeutic targets for gastric cancer precision medicine.

The fasting blood glucose and long non-coding RNA SNHG8 predict poor prognosis in patients with gastric carcinoma after radical gastrectomy

This prospective study sought to evaluate the prediction of fasting blood glucose and long non-coding RNA (lncRNA) SNHG8 for the risk of gastric carcinoma mortality. A total of 217 gastric carcinoma patients underwent radical gastrectomy were included during 2012-16. The final follow-up was finished in January 2017. The aggregate hazard ratio(HR) demonstrated that poor prognosis of gastric carcinoma was associated with fasting blood glucose (HR= 1.29, P=0.037), SNHG8 expression(HR = 1.10, P= 0.009), positive distant metastasis(HR = 2.99, P= 0.020), EBV positive (HR = 3.40, P=0.002), and tumor size more than 5.0 cm (HR = 3.36, P= 0.005). In survival analysis, elevated fasting blood glucose (P =0.007) and high SNHG8 expression (P =0.007) were significantly associated with shorter survival times in gastric cancer. Significant multiplicative interaction was shown between fasting blood glucose and SNHG8 expression (chi-squared=7.81, P_{multiplicative} =0.005), without statistical additive interaction. Fasting blood glucose and SNHG8 expression could predict poor prognosis after radical gastrectomy. LncRNA SNHG8 could be applied as a novel epigenetic molecular target in gastric carcinoma.

Identification of a 6-lncRNA prognostic signature based on microarray re-annotation in gastric cancer

Gastric cancer (GC) remains an important malignancy worldwide with poor prognosis. Long noncoding RNAs (lncRNAs) can markedly affect cancer progression. Moreover, lncRNAs have been proposed as diagnostic or prognostic biomarkers of GC. Therefore, the current study aimed to explore lncRNA‐based prognostic biomarkers for GC. LncRNA expression profiles from the Gene Expression Omnibus (GEO) database were first downloaded. After re‐annotation of lncRNAs, a univariate Cox analysis identified 177 prognostic lncRNA probes in the training set http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE62254 (n = 225). Multivariate Cox analysis of each lncRNA with clinical characteristics as covariates identified a total of 46 prognostic lncRNA probes. Robust likelihood‐based survival and least absolute shrinkage and selection operator (LASSO) models were used to establish a 6‐lncRNA signature with prognostic value. Receiver operating characteristic (ROC) curve analyses were employed to compare survival prediction in terms of specificity and sensitivity. Patients with high‐risk scores exhibited a significantly worse overall survival (OS) than patients with low‐risk scores (log‐rank test P‐value <.0001), and the area under the ROC curve (AUC) for 5‐year survival was 0.77. A nomogram and forest plot were constructed to compare the clinical characteristics and risk scores by a multivariable Cox regression analysis, which suggested that the 6‐lncRNA signature can independently make the prognosis evaluation of patients. Single‐sample GSEA (ssGSEA) was used to determine the relationships between the 6‐lncRNA signature and biological functions. The internal validation set http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE62254 (n = 75) and the external validation set http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE57303 (n = 70) were successfully used to validate the robustness of our 6‐lncRNA signature. In conclusion, based on the above results, the 6‐lncRNA signature can effectively make the prognosis evaluation of GC patients.

MALAT1 promotes gastric adenocarcinoma through the MALAT1/miR-181a-5p/AKT3 axis

Gastric adenocarcinoma, which originates from the gastric mucosal epithelium, has the highest incidence among various malignant tumours in China. As a crucial long non-coding RNA, metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) has been suggested to play an important role in many tumours. Here, we aimed to investigate the role and underlying mechanism of MALAT1 in gastric adenocarcinoma. Quantitative reverse transcription polymerase chain reaction was applied to determine the expression levels of MALAT1 in serum and cell lines. A CCK-8 assay and a clonogenic survival assay were used to examine cell proliferation and apoptosis. The protein level of RAC-γ serine/threonine-specific protein kinase (AKT3) was determined by western blot. Our results showed that MALAT1 was highly expressed in the serum of patients with gastric adenocarcinoma and in cell lines. Downregulating MALAT1 inhibited proliferation and promoted apoptosis of MGC-803 cells. In addition, MALAT1 directly targeted and decreased the expression of miR-181a-5p, which in turn upregulated the expression of AKT3. Further, overexpressing miR-181a-5p or directly inhibiting the AKT pathway with the inhibitor ipatasertib exhibited similar effects to MALAT1 knockdown. Our research proposes a novel mechanism where the role of MALAT1 is dependent on the MALAT1/miR-181a-5p/AKT3 axis. MALAT1 competes with AKT3 for miR-181a-5p binding, thereby upregulating the AKT3 protein level and ultimately promoting the growth of gastric adenocarcinoma.

Downregulation of Long Non-coding RNA FALEC Inhibits Gastric Cancer Cell Migration and Invasion Through Impairing ECM1 Expression by Exerting Its Enhancer-Like Function

Long non-coding RNAs (lncRNAs) have been shown to play important roles in many human diseases. However, their functions and mechanisms in tumorigenesis and development remain largely unknown. Here, we demonstrated that focally amplified lncRNA in epithelial cancer (FALEC) was upregulated and significantly correlated with lymph node metastasis, TNM stage in gastric cancer (GC). Further experiments revealed that FALEC knockdown significantly inhibited GC cells migration and invasion in vitro. Mechanistic investigations demonstrated that small interfering RNA-induced silencing of FALEC decreased expression of the nearby gene extracellular matrix protein 1 (ECM1) in cis. Additionally, ECM1 and FALEC expression were positively correlated, and high levels of ECM1 predicted shorter survival time in GC patients. Our results suggest that the downregulation of FALEC significantly inhibited the migration and invasion of GC cells through impairing ECM1 expression by exerting an enhancer-like function. Our work provides valuable information and a novel promising target for developing new therapeutic strategies in GC.

Gene Expression Analysis of Two Epithelial-mesenchymal Transition-related Genes: Long Noncoding RNA-ATB and SETD8 in Gastric Cancer Tissues

Background

Cancer is the second cause of death after cardiovascular diseases worldwide. Tumor metastasis is the main cause of death in patients with cancer; therefore, unraveling the molecular mechanisms involved in metastasis is critical. Epithelial-mesenchymal transition (EMT) is believed to promote tumor metastasis. Based on the critical roles of long noncoding RNA-ATB (lncRNA-ATB) and SETD8 genes in cancer pathogenesis and EMT, in this study, we aimed to assess expression profile and clinicopathological relevance of these two genes in human gastric cancer.

Materials and Methods

Quantitative real-time polymerase chain reaction was performed to assess these gene expressions in gastric cancer tissues and various cell lines. The associations between these gene expressions and clinicopathological characteristics were also analyzed.

Results

Insignificant downregulation of lncRNA-ATB and significant upregulation of SETD8 in cancerous versus noncancerous gastric tissues were observed. Among different examined cell lines, all displayed both genes expression. Except for a significant inverse correlation between the expression levels of lncRNA-ATB and depth of invasion (T) and a direct association between SETD8 levels and advanced tumor grades, no significant association was found with other clinicopathological characteristics.

Conclusion

lncRNA-ATB and SETD8 genes may play a critical role in gastric cancer progression and may serve as potential diagnostic/prognostic biomarkers in cancer patients.

Ameloblastoma RNA profiling uncovers a distinct non-coding RNA signature

Ameloblastoma of the jaws remains the top difficult to treat odontogenic tumour and has a high recurrence rate. New evidence suggests that non-coding RNAs (ncRNAs) play a critical role in tumourgenesis and prognosis of cancer. However, ameloblastoma ncRNA expression data is lacking. Here we present the first report of ameloblastoma ncRNA signatures. A total of 95 ameloblastoma cases and a global array transcriptome technology covering > 285.000 full-length transcripts were used in this two-step analysis. The analysis first identified in a test cohort 31 upregulated ameloblastoma-associated ncRNAs accompanied by signalling pathways of cancer, spliceosome, mRNA surveillance and Wnt. Further validation in an independent cohort points out the long non-coding (lncRNAs) and small nucleolar RNA (snoRNAs): LINC340, SNORD116-25, SNORA11, SNORA21, SNORA47 and SNORA65 as a distinct ncRNA signature of ameloblastoma. Importantly, the presence of these ncRNAs was independent of BRAF-V600E and SMO-L412F mutations, histology type or tumour location, but was positively correlated with the tumour size. Taken together, this study shows a systematic investigation of ncRNA expression of ameloblastoma, and illuminates new diagnostic and therapeutic targets for this invasive odontogenic tumour.

SNHG8 is identified as a key regulator of epstein-barr virus(EBV)-associated gastric cancer by an integrative analysis of lncRNA and mRNA expression

The Epstein-Barr virus (EBV) is associated with a variety of cancers, including gastric cancer, which has one of the highest mortality rates of all human cancers. Long non-coding RNAs (lncRNAs) have been suggested to have important causal roles in gastric cancer. However, the interaction between lncRNAs and EBV has not yet been studied. To this end, we sequenced 11,311 lncRNAs and 144,826 protein-coding transcripts from four types of tissue: one non-EBV-infected gastric carcinoma (EBVnGC) and its adjacent normal tissue, and one EBV-associated gastric carcinoma (EBVaGC) and its adjacent normal tissue. Five lncRNAs showed EBVaGC-specific expression; of those, one (SNHG8) was validated using real-time PCR in an independent cohort with 88 paired gastric cancer and adjacent tissue samples. To explore the functions of SNHG8, we identified its mRNA targets on the lncRNA-mRNA co-expression network of the Illumina Body Map, which contains the RNA sequencing data of mRNAs and lncRNAs from 16 normal human tissues. SNHG8 lncRNA was found to affect several gastric cancer-specific pathways and target genes of EBV. Our results reveal the intertwined tumorigenesis mechanisms of lncRNA and EBV and identify SNHG8 as a highly possible candidate biomarker and drug target of gastric cancer.