LncRNAs: emerging biomarkers in gastric cancer

Investigating the effect of LncRNA DLGAP1-AS2 suppression on chemosensitivity of gastric cancer to chemotherapy

Gastric cancer, as the fifth most frequent disease and the fourth foremost cause of cancer-related death worldwide, remains a main clinical challenge due to its poor prognosis, limited treatment choices, and ability to metastasize. Combining siRNAs to suppress lncRNA with chemotherapeutic medications is a novel treatment approach that eventually increases the therapeutic efficacy of the drug while lessening its adverse effects. This study was performed with the purpose of examining the impact of inhibiting DLGAP1-AS2 expression on gastric cancer cells' drug chemosensitivity. AGS cells were cultured as the study cell line and were transfected with an optimum dose of DLGAP1-AS2 siRNA and then treated with oxaliplatin. Cell viability was examined using the MTT technique. Apoptosis and cell cycle were evaluated using Annexin V/PI staining and flow cytometry. Later, the scratch test was conducted to investigate the ability of cells to migrate, and the inhibition of the stemness of AGS cells was further investigated through the colony formation method. Finally, the qRT-PCR technique was used to assess the expression of Bax, Bcl-2, Caspase-3, p53, MMP-2, and CD44 genes. The MTT test indicated the effect of gene therapy with siRNA and oxaliplatin in combination reduced the chemotherapy drug dose to 29.92 µM and increased AGS cells' sensitivity to oxaliplatin. Also, the combination therapy caused a significant increase in apoptosis. However, it reduced the stemness feature, the rate of cell viability, proliferation, and metastasis compared to the effect of each treatment alone; the results also showed the arrest of the cell cycle in the Sub G1 phase after the combined treatment and a further reduction in the number and size of the formed colonies. Suppressing the expression of lncRNA DLGAP1-AS2 by siRNA followed by treatment with oxaliplatin can be utilized as an effective and new therapeutic technique for gastric cancer therapy.

Diagnostic value of long noncoding RNA SNHG15 in gastric cancer: in vitro and in silico studies

LncRNA SNHG15 has been recognized as the main factor in the progression of various cancer types. However, the underlying mechanisms are not well clarified. This research aimed to explore the diagnostic potential of SNHG15 in gastric cancer (GC) patients and also the effects of SNHG15-miRNA-mRNA network in GC pathobiology. The expression level of SNHG15 in GC tissues and adjacent normal tissues (ANTs) was evaluated by qRT-PCR and also considered in relation to clinicopathologic factors. The ROC curve was explored to consider the specificity and sensitivity of SNHG15. Gene ontology functional annotation and KEGG pathway analysis were performed in order to predict the effects of SNHG15-miRNA-mRNA network in GC pathobiology. SNHG15 was overexpressed in GC tissues compared to ANTs (fold change= 3.87 and P-value = 0.0022). The SNHG15 expression level was not significantly associated with clinicopathologic factors. ROC curve indicated the specificity of 63.51 and sensitivity of 79.73 and the AUC of 0.744 (P-value < 0.0001). Further gene network analysis revealed that SNHG15 interacts with has-miR-613, has-miR-542-3p, and has-miR-1236-3p, and may be involved in the GC pathobiology by affecting the EGFR tyrosine kinase inhibitor resistance, HIF-1 signaling pathway, and VEGF signaling pathway. It can be concluded that SNHG15 may be a diagnostic factor in GC and may contribute in a variety of cancer-related signaling pathways.

LncRNA CAI2 Contributes to Poor Prognosis of Glioma through the PI3K-Akt Signaling Pathway

AIMS

We aim to explore new potential therapeutic targets and markers in human glioma.

BACKGROUND

Gliomas are the most common malignant primary tumor in the brain.

OBJECTIVE

In the present research, we evaluated the effect of CAI2, a long non-coding RNA, on the biological behaviors of glioma and explored the related molecular mechanism.

METHODS

The expression of CAI2 was analyzed using qRT-PCR in 65 cases of glioma patients. The cell proliferation was determined with MTT and colony formation assays, and the PI3K-AKt signaling pathway was analyzed using western blot.

RESULTS

CAI2 was upregulated in human glioma tissue compared with the matched, adjacent nontumor tissue and was correlated with WHO grade. Survival analyses proved that the overall survival of patients with high CAI2 expression was poor compared to that of patients with low CAI2 expression. High CAI2 expression was an independent prognostic factor in glioma. The absorbance values in the MTT assay after 96 h were .712 ± .031 for the si-control and .465 ± .018 for the si- CAI2-transfected cells, and si-CAI2 inhibited colony formation in U251 cells by approximately 80%. The levels of PI3K, p-AKt, and AKt in si-CAI2-treated cells were decreased.

CONCLUSION

CAI2 may promote glioma growth through the PI3K-AKt signaling pathway. This research provided a novel potential diagnostic marker for human glioma.

OIP5-AS1/CD147/TRPM7 axis promotes gastric cancer metastasis by regulating apoptosis related PI3K-Akt signaling

Background

To explore the mechanism of OIP5-AS1/CD147/TRPM7 axis to gastric cancer (GC) metastasis.

Methods

Bioinformatic analysis was performed to pick up the candidate genes associated with regulation GC metastasis. Using GC cell lines, AGS and MKN-45 as research objects, identify the effect of candidate genes on GC metastasis, judge cell proliferation status by MTT assay and cell clone number, and detect cell migration by Transwell and Wound-healing assay. The molecular mechanism of CD147/OIP5/TRPM7 axis regulating GC metastasis was further explored by RNA sequencing. The key signaling pathways were subsequently verified by flow cytometry and WB.

Results

Bioinformatic analysis suggested OIP5-AS1/CD147/TRPM7 axis may be involving in GC metastasis. The RNA interference experiment proved that after gene interference, the proliferation ability of GC cells decreased significantly (P<0.05), which was manifested in the reduction of the number of cell clones. In addition, the migration ability of GC cells was also affected, which was based on the results of Wound Healing (P<0.05). CD147, OIP5-AS1 and TRPM7 all have harmful effects on GC cells. The relationship between OIP5-AS1 and CD147/TRPM7 was detected by RNA immunoprecipitation. Moreover, the RNA sequencing data indicated that CD147/OIP5-AS1/TRPM7 may coordinately regulate the PI3K-AKT pathway related to GC cell apoptosis, thereby affecting the proliferation and migration of GC cells. After RNA interference, the level of apoptosis increased both in AGS and MKN-45 cells. Meanwhile, the expression of pro-apoptotic proteins Caspase9 and BAX were up-regulated (P<0.05). In addition, the expression of PI3K and AKT proteins was reduced (P<0.05). The mouse tumorigenesis experiment corroborated the results of the in vitro study.

Conclusion

OIP5-AS1/CD147/TRPM7 axis reduces GC cell proliferation by regulating apoptosis associated with PI3K-AKT signaling, further affecting cancer metastasis.

Ribosomal DNA copy number alteration in blood sample from gastric cancer patients

BACKGROUND

Ribosomal DNA (rDNA) is the most abundant and important housekeeping gene in the cell. It usually acted as DNA damage sensor in DNA damage reaction. Gastric cancer (GC) as a tumor with high morbidity and mortality, it is hard to diagnosis in an early stage.

METHODS

In this study, we collected and test the copy number of rDNA in blood sample of 42 GC patients and 56 healthy controls (HC) to explore the relationship between rDNA and GC. Besides, we make a correlation between the copy number of rDNA and ten biomarkers (CYFR21-1, CA15-3, CA72-4, NSE, CEA, CA125, ProGRP, AFP, SCC, CA19-9).

RESULTS

The copy number of 18 S, 5.8 S, 28 S rDNA in GC is less than HC and 5 S is more than HC in their blood sample. And the expression of H-cox-1 and ND1 in GC is higher than HC in blood sample. it shows the expression of CA15-3 is related to ND1 and H-cox-1.

CONCLUSION

We found for the first time the changes of rDNA and mtDNA expression in the blood of patients with gastric cancer. All these finding suggests rDNA may have potential in diagnosing GC.

Knockdown of long non-coding RNA SNHG3 inhibits proliferation, migration and invasion of human thyroid cancer via miR-339-5p/GPR62 axis

Previous studies have implicated SNHG3, a long non-coding RNA, in various human cancers, suggesting its oncogenic role. However, its specific involvement in thyroid cancer and the underlying molecular mechanisms remain unclear. Therefore, this study aims to elucidate the role of SNHG3 in human thyroid cancer and its interaction with the miR-339-5p/GPR62 axis. Understanding these mechanisms could provide insights into potential therapeutic targets for managing thyroid cancer. Results revealed significant upregulation of SNHG3 in human thyroid cancer tissues and cell lines. Knockdown of SNHG3 significantly suppressed proliferation, migration and invasion of CUTC5 and IHH-4 thyroid cancer cells. Knockdown of SNHG3 induces apoptosis in CUTC5 and IHH-4 cells and also inhibits the growth of xenografted tumors in vivo. Different in vitro assays revealed the interaction of SNHG3 with microRNA-339-5p (miR-339-5p) in thyroid cancer cells. Expression of miR-339-5p was significantly downregulated in thyroid cancer tissues and cell lines. However, the knockdown of SNHG3 caused significant upregulation of miR-339-5p. Interestingly, overexpression of miR-339-5p exerted tumor-suppressive effects in CUTC5 and IHH-4 cells via post-transcriptional suppression of GPR62. Knockdown of GPR62 significantly inhibited the proliferation, migration and invasion of CUTC5 and IHH-4 cells. Nonetheless, inhibition of miR-339-5p or overexpression of GPR62 avoids the growth inhibitory effects of SNHG3 knockdown in CUTC5 and IHH-4 cells. Results indicated that SNHG3 exerts oncogenic molecular function in thyroid cancer via miR-339-5p/GPR62 axis and may act as a therapeutic target for its management.

Tumor- and metastasis-promoting roles of miR-488 inhibition via HULC enhancement and EZH2-mediated p53 repression in gastric cancer

Dysregulation of microRNAs (miRNAs or miRs) is implicated in the development of gastric cancer (GC), which is possibly related to their roles in targeting tumor-suppressive or tumor-promoting genes. Herein, the current study was intended to ascertain the function of miR-488 and its modulatory mechanism in GC. Initially, human GC cells were assayed for their in vitro malignancy after miRNA gain- or loss-of-function and RNA interference or overexpression. Also, tumorigenesis and liver metastasis were evaluated in nude mouse models. Results demonstrated that miR-488 elevation suppressed GC (MKN-45 and OCUM-1) cell proliferation, migration, and invasiveness in vitro and reduced their tumorigenesis and liver metastasis in vivo. The luciferase assay identified that miR-488 bound to HULC and inhibited its expression. Furthermore, HULC could enhance EZH2-H3K27me3 enrichment at the p53 promoter region and epigenetically repress the p53 expression based on the data from RIP- and ChIP-qPCR assay. Additionally, HULC was validated to enhance GC growth and metastasis in vitro and in vivo. Overall, HULC re-expression elicited by miR-488 inhibition can enhance EZH2-H3K27me3 enrichment in the p53 promoter and repress the p53 expression, thus promoting the growth and metastasis of GC.

Integrating multiple machine learning algorithms for prognostic prediction of gastric cancer based on immune-related lncRNAs

Background: Long non-coding RNAs (lncRNAs) play an important role in the immune regulation of gastric cancer (GC). However, the clinical application value of immune-related lncRNAs has not been fully developed. It is of great significance to overcome the challenges of prognostic prediction and classification of gastric cancer patients based on the current study.

Methods: In this study, the R package ImmLnc was used to obtain immune-related lncRNAs of The Cancer Genome Atlas Stomach Adenocarcinoma (TCGA-STAD) project, and univariate Cox regression analysis was performed to find prognostic immune-related lncRNAs. A total of 117 combinations based on 10 algorithms were integrated to determine the immune-related lncRNA prognostic model (ILPM). According to the ILPM, the least absolute shrinkage and selection operator (LASSO) regression was employed to find the major lncRNAs and develop the risk model. ssGSEA, CIBERSORT algorithm, the R package maftools, pRRophetic, and clusterProfiler were employed for measuring the proportion of immune cells among risk groups, genomic mutation difference, drug sensitivity analysis, and pathway enrichment score.

Results: A total of 321 immune-related lncRNAs were found, and there were 26 prognostic immune-related lncRNAs. According to the ILPM, 18 of 26 lncRNAs were selected and the risk score (RS) developed by the 18-lncRNA signature had good strength in the TCGA training set and Gene Expression Omnibus (GEO) validation datasets. Patients were divided into high- and low-risk groups according to the median RS, and the low-risk group had a better prognosis, tumor immune microenvironment, and tumor signature enrichment score and a higher metabolism, frequency of genomic mutations, proportion of immune cell infiltration, and antitumor drug resistance. Furthermore, 86 differentially expressed genes (DEGs) between high- and low-risk groups were mainly enriched in immune-related pathways.

Conclusion: The ILPM developed based on 26 prognostic immune-related lncRNAs can help in predicting the prognosis of patients suffering from gastric cancer. Precision medicine can be effectively carried out by dividing patients into high- and low-risk groups according to the RS.

A comprehensive review of the role of lncRNAs in gastric cancer (GC) pathogenesis, immune regulation, and their clinical applications

Gastric cancer (GC) is the fifth most common malignant tumor and the third leading cause of cancer-related deaths worldwide. Although numerous studies have been conducted on advanced GC, the molecular mechanisms behind it remain obscure. Long non-coding RNAs (lncRNAs) are a family of RNA transcripts capable of regulating target genes at transcriptional, post-transcriptional, and translational stages. They do this by modifying mRNAs, miRNAs, and proteins. These RNAs are critical regulators of many biological processes, including gene epigenetics, transcription, and post-transcriptional levels. This article highlights recent results on lncRNAs involved in drug resistance, proliferation, migration, angiogenesis, apoptosis, autophagy, and immune response in GC. The potential clinical implications of lncRNAs as biomarkers and therapeutic targets in GC are also discussed.

Oncogenic LINC00857 recruits TFAP2C to elevate FAT1 expression in gastric cancer

FAT atypical cadherin 1 (FAT1) is a mutant gene frequently found in human cancers and mainly accumulates at the plasma membrane of cancer cells. Emerging evidence has implicated FAT1 in the progression of gastric cancer (GC). This study intended to identify a regulatory network related to FAT1 in GC development. Upregulated expression of FAT1 was confirmed in GC tissues, and silencing FAT1 was observed to result in suppression of GC cell oncogenic phenotypes. Mechanistic investigation results demonstrated that FAT1 upregulated AP-1 expression by phosphorylating c-JUN and c-FOS, whereas LINC00857 elevated the expression of FAT1 by recruiting a transcription factor TFAP2C. Functional experiments further suggested that LINC00857 enhanced the malignant biological characteristics of GC cells through TFAP2C-mediated promotion of FAT1. More importantly, LINC00857 silencing delayed the tumor growth and blocked epithelial-mesenchymal transition in tumor-bearing mice, which was associated with downregulated expression of TFAP2C/FAT1. To conclude, LINC00857 plays an oncogenic role in GC through regulating the TFAP2C/FAT1/AP-1 axis. Therefore, this study contributes to extended the understanding of gastric carcinogenesis and LINC00857 may serve as a therapeutic target for GC.

Network analysis reveals that the tumor suppressor lncRNA GAS5 acts as a double-edged sword in response to DNA damage in gastric cancer

The lncRNA GAS5 acts as a tumor suppressor and is downregulated in gastric cancer (GC). In contrast, E2F1, an important transcription factor and tumor promoter, directly inhibits miR-34c expression in GC cell lines. Furthermore, in the corresponding GC cell lines, lncRNA GAS5 directly targets E2F1. However, lncRNA GAS5 and miR-34c remain to be studied in conjunction with GC. Here, we present a dynamic Boolean network to classify gene regulation between these two non-coding RNAs (ncRNAs) in GC. This is the first study to show that lncRNA GAS5 can positively regulate miR-34c in GC through a previously unknown molecular pathway coupling lncRNA/miRNA. We compared our network to several in-vivo/in-vitro experiments and obtained an excellent agreement. We revealed that lncRNA GAS5 regulates miR-34c by targeting E2F1. Additionally, we found that lncRNA GAS5, independently of p53, inhibits GC proliferation through the ATM/p38 MAPK signaling pathway. Accordingly, our results support that E2F1 is an engaging target of drug development in tumor growth and aggressive proliferation of GC, and favorable results can be achieved through tumor suppressor lncRNA GAS5/miR-34c axis in GC. Thus, our findings unlock a new avenue for GC treatment in response to DNA damage by these ncRNAs.

Overexpression of lncRNA TCLlnc1 in gastric cancer predicts postoperative distant recurrence and poor survival

TCLlnc1 was characterized as a lncRNA with oncogenic roles in T cell lymphoma, whereas its role in other diseases is unknown. We then explored the involvement of TCLlnc1 in gastric cancer. Paired gastric cancer and nontumor tissues from 66 gastric cancer patients were used to extract total RNA samples, which were used to perform RT-qPCRs to determine the expression of TCLlnc1. Plasma samples from these 66 gastric cancer patients and 66 healthy controls were also used to detect circulating TCLlnc1. Correlations of TCLlnc1 in both plasma and tissue samples with patients’ clinical data were analyzed by chi-square t-test. The diagnostic value of TCLlnc1 for early-stage gastric cancer was analyzed with the receiver operating characteristic curve. A 5-year follow-up study was performed to explore the prognostic value of TCLlnc1 for the survival of gastric cancer patients. TCLlnc1 expression in tissue was increased in gastric cancer. Plasma TCLlnc1 was also increased in gastric cancer. Plasma TCLlnc1 was closely correlated with TCLlnc1 in gastric cancer tissues, but not TCLlnc1 in nontumor tissues. TCLlnc1 in plasma was only correlated with tumor distant metastasis, but not other clinical data. TCLlnc1 in plasma showed promising diagnostic value for stage I and II gastric cancer. Increased accumulation of TCLlnc1 was closely correlated with distant recurrence and poor survival during a 5-year follow-up. Therefore, TCLlnc1 is overexpressed in gastric cancer predicts postoperative distant recurrence and poor survival.

Identification and Validation of Apparent Imbalanced Epi-lncRNAs Prognostic Model Based on Multi-Omics Data in Pancreatic Cancer

Background: Globally, pancreatic adenocarcinoma is a recognized cause of pancreatic death (PAAD) associated with high mortality. Long non-coding RNAs (lncRNAs) play an important role in several biological processes in pancreatic cancer.

Methods: The gene expression profile of PAAD patients were obtained from The Cancer Genome Atlas (TCGA) database. The limma package was used to identify epigenetic disorders of lncRNAs and PCG. Subsequently, the genomic characteristics and landscape of lncRNAs were explored. The pancreatic cancer-related lncRNAs gene set from Lnc2Cancer v3.0 were collected and the difference between cancer samples and normal samples were analysed. A prognostic model consisting of five epigenetic lncRNA (epi-lncRNAs) was established by univariate and multivariate Cox proportional hazards regression analyses and was verified across different data sets. Finally, the expression of core epi-lncRNAs was identified by PCR experiment.

Results: A total of 2237 epi-lncRNAs, 11855 non-epi-lncRNAs, 13518 epi-PCGs, and 6097 non-epi-PCGs, were identified. The abnormal frequency of lncRNAs in pancreatic cancer was much lower than that in PCG, and 138 epi-lncRNAs were enriched in human cancer-related lncRNAs. Epi-lncRNAs had a higher number with longer lengths and a greater number of transcripts. Epi-lncRNAs associated with epigenetic disorders had a higher number of exons, gene length, and isomers as compared to non-epi-lncRNAs. Further, the five pancreatic cancer-specific epi-lncRNA genes (AL161431.1, LINC00663, LINC00941, SNHG10, and TM4SF1-AS1) were identified. Based on these five pancreatic cancer-specific epis-lncRNAs, a prognostic model for pancreatic cancer was established. The RT-PCR result confirmed that AL161431.1, LINC00663, LINC00941, and SNHG10 expressions in pancreatic cancer samples were higher as compared to normal pancreatic samples; the expression of TM4SF1-AS1 in pancreatic cancer cells was significantly lower than that in normal pancreatic samples.

Conclusions: Epigenetic abnormalities could promote abnormal lncRNA expression in pancreatic cancer and may play an important role in its progression.

Differential Long Non-Coding RNA Expression Analysis in Chronic Non-Atrophic Gastritis, Gastric Mucosal Intraepithelial Neoplasia, and Gastric Cancer Tissues

Gastric cancer (GC) has a high incidence worldwide, and when detected, the majority of patients have already progressed to advanced stages. Long non-coding RNAs (lncRNAs) have a wide range of biological functions and affect tumor occurrence and development. However, the potential role of lncRNAs in GC diagnosis remains unclear. We selected five high-quality samples from each group of chronic non-atrophic gastritis, gastric mucosal intraepithelial neoplasia, and GC tissues for analysis. RNA-seq was used to screen the differentially expressed lncRNAs, and we identified 666 differentially expressed lncRNAs between the chronic non-atrophic gastritis and GC groups, 13 differentially expressed lncRNAs between the gastric mucosal intraepithelial neoplasia and GC groups, and 507 differentially expressed lncRNAs between the chronic non-atrophic gastritis and gastric mucosal intraepithelial neoplasia groups. We also identified six lncRNAs (lncRNA H19, LINC00895, lnc-SRGAP2C-16, lnc-HLA-C-2, lnc-APOC1-1, and lnc-B3GALT2-1) which not only differentially expressed between the chronic non-atrophic gastritis and GC groups, but also differentially expressed between the gastric mucosal intraepithelial neoplasia and GC groups. Furthermore, RT-qPCR was used to verify the differentially co-expressed lncRNAs. LncSEA was used to conduct a functional analysis of differentially expressed lncRNAs. We also predicted the target mRNAs of the differentially expressed lncRNAs through bioinformatics analysis and analyzed targeting correlations between three differentially co-expressed lncRNAs and mRNAs (lncRNA H19, LINC00895, and lnc-SRGAP2C-16). Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases were used to explore the functions of target mRNAs of differentially expressed lncRNAs. In conclusion, our study provides a novel perspective on the potential functions of differentially expressed lncRNAs in GC occurrence and development, indicating that the differentially expressed lncRNAs might be new biomarkers for early GC diagnosis.

Zooming in on Long Non-Coding RNAs in Ewing Sarcoma Pathogenesis

Ewing sarcoma (ES) is a rare aggressive cancer of bone and soft tissue that is mainly characterized by a reciprocal chromosomal translocation. As a result, about 90% of cases express the EWS-FLI1 fusion protein that has been shown to function as an aberrant transcription factor driving sarcomagenesis. ES is the second most common malignant bone tumor in children and young adults. Current treatment modalities include dose-intensified chemo- and radiotherapy, as well as surgery. Despite these strategies, patients who present with metastasis or relapse still have dismal prognosis, warranting a better understanding of treatment resistant-disease biology in order to generate better prognostic and therapeutic tools. Since the genomes of ES tumors are relatively quiet and stable, exploring the contributions of epigenetic mechanisms in the initiation and progression of the disease becomes inevitable. The search for novel biomarkers and potential therapeutic targets of cancer metastasis and chemotherapeutic drug resistance is increasingly focusing on long non-coding RNAs (lncRNAs). Recent advances in genome analysis by high throughput sequencing have immensely expanded and advanced our knowledge of lncRNAs. They are non-protein coding RNA species with multiple biological functions that have been shown to be dysregulated in many diseases and are emerging as crucial players in cancer development. Understanding the various roles of lncRNAs in tumorigenesis and metastasis would determine eclectic avenues to establish therapeutic and diagnostic targets. In ES, some lncRNAs have been implicated in cell proliferation, migration and invasion, features that make them suitable as relevant biomarkers and therapeutic targets. In this review, we comprehensively discuss known lncRNAs implicated in ES that could serve as potential biomarkers and therapeutic targets of the disease. Though some current reviews have discussed non-coding RNAs in ES, to our knowledge, this is the first review focusing exclusively on ES-associated lncRNAs.

Long Non-coding RNA HOXA11-AS Facilitates Proliferation of Lung Adenocarcinoma Cells via Targeting the Let-7c-5p/IGF2BP1 Axis

Objective: This study investigates the relationship between the HOXA11-AS/let-7c-5p/IGF2BP1 regulatory axis and lung adenocarcinoma.

Methods: The expression levels of HOXA11-AS, let-7c-5p, and IGF2BP1 were evaluated in LUAD tissue and cell lines. Subcellular fractionation detection assay was adopted to verify the HOXA11-AS distribution in LUAD cells. The interaction relationship between let-7c-5p and HOXA11-AS or IGF2BP1 was validated by dual-luciferase reporter detection. In RNA binding protein immunoprecipitation assay, the binding relationship between HOXA11-AS and let-7c-5p was identified. The cell viability of transfected cells was tested by the Cell Counting Kit-8 assay. The mouse xenograft model was used to identify the effect of HOXA11-AS on tumor growth in vivo.

Results: Upregulation of lncRNA HOXA11-AS was found in LUAD, and suppression of HOXA11-AS could suppress the proliferative ability of LUAD cells. The let-7c-5p was expressed to be downregulated, which played an inhibitory role in LUAD cell proliferation. Let-7c-5p was negatively regulated by HOXA11-AS. HOXA11-AS promoted LUAD cell proliferation, while let-7c-5p had an inverse effect. Besides, IGF2BP1, regulated by let-7c-5p, had a positive relation with HOXA11-AS, while overexpression of IGF2BP1 could suppress the inhibition of silencing HOXA11-AS on LUAD cell proliferation. Experiments on mice confirmed that HOXA11-AS facilitated LUAD cell growth in vivo through regulating the let-7c-5p/IGF2BP1 axis.

Conclusion: HOXA11-AS promoted LUAD cell proliferation by targeting let-7c-5p/IGF2BP1, which could be potential molecular targets for LUAD.

+HOXA10-AS Promotes Malignant Phenotypes of Gastric Cancer via Upregulating HOXA10

Objective

To study the role of long noncoding RNA HOXA10-AS in gastric cancer (GC) and its underlying mechanism which is one of the most common and fetal malignancies. Long noncoding RNA HOXA10-AS is highly expressed and acts in an oncogenic role in cancers. However, its roles in GC are still unknown.

Methods

The expression of HOXA10-AS and HOXA10 in GC tissues from the TCGA database was analyzed. Western blot and qRT-PCR assays were applied to examine the expression of HOXA10-AS and HOXA10. Cell proliferation was evaluated with CCK-8 and EdU incorporation assays. Cell apoptosis was analyzed by flow cytometry. Migratory and invasive capacities were evaluated with wound healing and transwell assays.

Results

HOXA10-AS and HOXA10 were upregulated in GC, and their expressions were positively correlated. Knockdown of HOXA10-AS inhibited HOXA10 expression in GC cells. Furthermore, knockdown of HOXA10-AS restrained GC cell proliferation, migration, and invasion but promoted apoptosis. In addition, overexpression of HOXA10-AS promoted malignant phenotypes of GC cells, but all these effects could be reversed by knockdown of HOXA10.

Conclusion

HOXA10-AS promoted GC cell proliferation, migration and invasion and enhanced apoptosis via upregulating HOXA10. Our study implies a novel regulatory mechanism of malignant phenotypes and provides potential therapeutic targets for GC.

Long non-coding RNA CCL2 promoted gastric cancer function via miR-128/ PARP2 signal pathway

Amounts of studies have revealed long non-coding RNA (lncRNA) was related to the development of gastric cancer. Here, our results suggested the function and regulatory mechanism of CCL2 in gastric cancer. Quantitative polymerase-chain reaction (qPCR) was employed to inspect lncRNA CCL2 and miR-128 expression in normal gastric cell line (GES-1) and tumor cell lines (HGC-27 and MKN-45). The effects of CCL2 and miR-128 were measured via Luciferase reporter test. Western blot was used to check PARP2 protein expression. CCL2 expression and PARP2 protein levels were up-regulated, while miR-128 expression was obviously lower. Meanwhile, CCL2 down-regulating significantly repressed the proliferation, migration, and invasion by regulating miR-128. In addition, we proved miR-128 was a direct target of CCL2 through double luciferase assay and bioinformatics analysis. Moreover, miR-128 markedly inhibited the proliferation, migration, and invasion in gastric cancer. More importantly, miR-128 could reverse the effects of lncRNA CCL2 knocked down. PARP2-si obviously suppressed in gastric cancer proliferation, migration, and invasion. Meanwhile, miR-128 mimic and the knockout of CCL2 distinctly decreased PARP2 protein level. Additionally, luciferase report experiments certificated that PARP2 targeted miR-128, implying PARP2 directly interacted with miR-128 in gastric cancer. More interestingly, the downregulation of PARP could reverse the trend triggered by miR-128 inhibitor in gastric tumor. All over these results showed lncRNA CCL2 played importance of role in gastric tumor via miR-128/PARP2 axis signal pathway. LncRNA CCL2 accelerated gastric cancer progression by regulating miR-128/PARP2 signaling pathway, providing a novel possible strategy for the treatment of gastric cancer.

SLCO4A1-AS1 Facilitates the Malignant Phenotype via miR-149-5p/STAT3 Axis in Gastric Cancer Cells

Solute carrier organic anion transporter family member 4A1 (SLCO4A1-AS1), a newly discovered lncRNA, may exert effects in tumors. Since its role in gastric cancer remains obscure, we sought to explore the mechanism of SLCO4A1-AS1 in gastric cancer. The relationship among SLCO4A1-AS1, miR-149-5p, and STAT3 was detected by bioinformatics, dual luciferase analysis, and Pearson's test, and the expressions of these genes were determined by quantitative real-time PCR and Western blot. Moreover, CCK-8, flow cytometry, wound healing assay, and Transwell analysis were performed to verify the function of SLCO4A1-AS1 in gastric cancer. Rescue experiments were used to detect the role of miR-149-5p. The expressions of SLCO4A1-AS1 and STAT3 were increased, while the expression of miR-149-5p was suppressed in gastric cancer tissues and cell lines. In addition, STAT3 expression was negatively correlated with miR-149-5p expression but was positively correlated with SLCO4A1-AS1 expression. Overexpression of SLCO4A1-AS1 promoted cell viability, migration, invasion, and STAT3 expression but suppressed apoptosis, while knockdown of SLCO4A1-AS1 had the opposite effect. SLCO4A1-AS1 bound to miR-149-5p and targeted STAT3. Moreover, miR-149-5p mimic inhibited the malignant development of gastric cancer cells and obviously reversed the function of SLCO4A1-AS1 overexpression. Our research reveals that abnormally increased SLCO4A1-AS1 expression may be an important molecular mechanism in the development of gastric cancer.

Phosphoglycerate kinase 1 silencing by a novel microRNA microRNA-4523 protects human osteoblasts from dexamethasone through activation of Nrf2 signaling cascade

Nuclear-factor-E2-related factor 2 (Nrf2) cascade activation can ameliorate dexamethasone (DEX)-induced oxidative injury and death in human osteoblasts. Phosphoglycerate kinase 1 (PGK1) depletion is shown to efficiently activate Nrf2 signaling by inducing methylglyoxal modification of Kelch-like ECH-associated protein 1 (Keap1). We here identified a novel PGK1-targeting microRNA: microRNA-4523 (miR-4523). RNA fluorescent in situ hybridization, RNA pull-down, and Argonaute-2 RNA immunoprecipitation results confirmed a direct binding between miR-4523 and PGK1 mRNA in primary human osteoblasts and hFOB1.19 osteoblastic cells. Forced overexpression of miR-4523, using a lentiviral construct, robustly decreased PGK1 3'-UTR (untranslated region) luciferase activity and downregulated its expression in human osteoblasts and hFOB1.19 cells. Furthermore, miR-4523 overexpression activated the Nrf2 signaling cascade, causing Keap1-Nrf2 disassociation, Nrf2 protein stabilization, and its nuclear translocation as well as transcription activation of Nrf2-dependent genes (NQO1, GCLC, and HO1) in human osteoblasts. By expressing a UTR-null PGK1 construct, miR-4523 overexpression-induced Nrf2 cascade activation was however largely inhibited. Importantly, DEX-induced reactive oxygen species production, oxidative injury, and cell apoptosis were significantly attenuated by miR-4523 overexpression in human osteoblasts and hFOB1.19 cells. Such actions by miR-4523 were abolished by Nrf2 shRNA or knockout, but mimicked by PGK1 knockout (using CRISPR/Cas9 method). In PGK1 knockout human osteoblasts, miR-4523 overexpression failed to further increase Nrf2 cascade activation and offer osteoblast cytoprotection against DEX. Significantly, miR-4523 is downregulated in human necrotic femoral head tissues of DEX-taking patients. Together, PGK1 silencing by miR-4523 protected human osteoblasts from DEX through activation of the Nrf2 signaling cascade.

SNHG10 Promotes Cell Proliferation and Migration in Gastric Cancer by Targeting miR-495-3p/CTNNB1 Axis

BACKGROUND

Long non-coding RNAs have been acknowledged as the crucial regulators in the progression of human cancers, including gastric cancer (GC). Small nucleolar RNA host gene 10 (SNHG10) has been identified as an oncogene in several cancer types. Nonetheless, it is unclear whether SNHG10 exerts functions in GC cells.

AIMS

The aims of the current study were to explore the function and underlying mechanism of SNHG10 in GC.

METHODS

The expression levels of SNHG10, miR-495-3p and catenin beta 1 (CTNNB1) were detected by RT-qPCR. Loss-of-function assays, including CCK-8, colony formation assay, flow cytometry analysis and transwell assays, were conducted to verify the effect of SHNG10 on the proliferation, apoptosis, migration and invasion of GC cells. Mechanism experiments were performed to identify the downstream molecular mechanism of SNHG10.

RESULTS

SNHG10 was expressed at a high level in GC cells. Knockdown of SNHG10 inhibited the proliferation, migration and invasion of GC cells. Silencing of SNHG10 led to the downregulation of core factors of WNT signaling pathway. Knockdown of SNHG10 could decline the expression of CTNNB1 through sequestering miR-495-3p.

CONCLUSIONS

SNHG10 promotes the procession of GC through targeting miR-495-3p/CTNNB1 and activating WNT signaling pathway.

ILF3-AS1 promotes cell proliferation and inhibits cell apoptosis of breast cancer by binding with miR-4429 to upregulate RAB14

As one of the leading causes of cancer-related deaths among women, breast cancer accounts for a 30% increase of incidence worldwide since 1970s. Recently, increasing studies have revealed that the long non-coding RNA ILF3-AS1 is involved in the progression of various cancers. Nevertheless, the role of ILF3-AS1 in breast cancer remains largely unknown. In the present study, we found that ILF3-AS1 was highly expressed in breast cancer tissues and cells. ILF3-AS1 silencing inhibited breast cancer cell proliferation, migration and invasion, and promoted cell apoptosis. ILF3-AS1 bound with miR-4429 in breast cancer cells. Moreover, RAB14 was a downstream target of miR-4429, and miR-4429 expression was negatively correlated with RAB14 or ILF3-AS1 expression in breast cancer tissues. The result of rescue experiments demonstrated that overexpression of RAB14 can reverse the inhibitory effect of ILF3-AS1 knockdown on breast cancer cell proliferation, migration and invasion. Overall, ILF3-AS1 promotes the malignant phenotypes of breast cancer cells by interacting with miR-4429 to regulate RAB14, which might offer a new insight into the underlying mechanism of breast cancer.

LINC00943 is correlated with gastric cancer and regulates cancer cell proliferation and chemosensitivity via hsa-miR-101-3p

BACKGROUND

Non-coding RNAs have emerged as important regulators in human cancers. In this work, we investigated the role of long intergenic non-protein-coding RNA 943 (LINC00943) in gastric cancer (GC).

METHODS

LINC00943 expression was evaluated in GC patient tissues and cell lines. In SNU-5 and MKN-45 cells, LINC00943 was knocked down to investigate its roles in regulating GC cell proliferation, 5-FU chemosensitivity and in vivo explant growth. Possible downstream target of LINC00943, human mature microRNA-101-3p (hsa-miR-101-3p) was also evaluated.

RESULTS

LINC00943 was aberrantly overexpressed in in situ GC tumors and immortal GC cell lines. LINC00943 overexpression was associated with GC patients' poor prognosis. LINC00943 knockdown reduced GC cell proliferation, 5-FU resistance and in vivo explant growth. Hsa-miR-101-3p was found to be regulated by LINC00943 in GC. Hsa-miR-101-3p downregulation reversed the tumor-suppressing functions of LINC00943 knockdown in GC cells.

CONCLUSION

In summary, our results indicated that LINC00943 was correlated with gastric cancer and regulates cancer cell proliferation and chemosensitivity via hsa-miR-101-3p.

LncRNA PINK1-AS promotes Gαi1-driven gastric cancer tumorigenesis by sponging microRNA-200a

Gastric cancer (GC) is one of the leading causes of human mortality around the world. We have previously shown that Gαi1 (the inhibitory subunit 1 of the heterotrimeric guanine nucleotide-binding protein) recruitment to ligand-activated receptor tyrosine kinases (RTKs) is essential for signaling. Testing its role in GC cancer-promoting functions, we found that Gαi1 is upregulated in human GC, correlating with poor overall survival. In established and primary human GC cells, Gαi1 shRNA (small hairpin RNA) or knockout produced significant anti-GC cell activity, proliferation and migration was inhibited, and apoptosis was activated. Conversely, ectopic Gαi1 overexpression promoted proliferation and migration of GC cells in vitro. By examining the tumor-suppressive miRNA microRNA-200a (miR-200a), we found that miR-200a directly silenced Gαi1 to induce anti-GC cell activity. The expression of miR-200a was downregulated in human GC, correlating with upregulation of a novel miR-200a-targeting long non-coding RNA (LncRNA), PINK1 (PTEN Induced Kinase 1)-AS. RNA immunoprecipitation, RNA-pull down, and RNA fluorescence in situ hybridization assays confirmed that PINK1-AS directly binds to miR-200a. Silencing PINK1-AS in GC cells led to miR-200a accumulation, Gαi1 downregulation, and inhibition of GC cell progression in vitro, whereas PINK1-AS upregulation produced the converse results. Significantly, anti-GC cell activity induced by PINK1-AS shRNA was ameliorated by the expression of miR-200a antisense or the 3'-UTR (untranslated region)-depleted Gαi1. In vivo, the growth of subcutaneous MGC-803 xenografts in nude mice was inhibited by PINK1-AS shRNA, but accelerated by PINK1-AS overexpression. Patient-derived GC xenograft growth in nude mice was largely inhibited after intratumoral injection of PINK1-AS shRNA lentivirus. In conclusion, PINK1-AS promotes Gαi1-driven GC progression by sponging miR-200a.

Silencing of long non-coding RNA XIST represses gastric cancer progression through blocking NFκB pathway via inhibiting HNF4A-mediated transcription of EPHA1

Gastric cancer (GC) is a common cancer and a leading cause of cancer-related deaths worldwide. Recent studies have supported the important role of long non-coding RNAs (lncRNAs) in GC progression. This study identified functional significance of X inactive specific transcript (XIST) in GC. The expression of XIST and EPHA1 in GC tissues and cells was measured. Then, dual luciferase reporter gene assay, RNA immunoprecipitation (RIP) assay and Chromatin Immunoprecipitation (ChIP) assay were performed to explore the interaction among XIST, EPHA1 and HNF4A. The effects of XIST on GG progression were evaluated by determining expression of proliferation- and invasion-related proteins (Ki67, PCNA, MMP-2, and MMP-9). Further, the functional role of XIST in GC with the involvement of NFκB pathway was also analyzed. Subsequently, the tumor growth in nude mice was evaluated. High expression of XIST and EPHA1 was observed in GC. XIST elevated EPHA1 expression by recruiting HNF4A. In addition, silencing of XIST inhibited GC progression in vitro and in vivo. Overexpressed XIST and EPHA1 yielded a reversed effect on cell proliferation and invasion. SN50 treatment (inhibitor of NFκB pathway) counteracted the promotive effect on GC cell proliferation and invasion mediated by XIST. The present study unveils that XIST increases the enrichment of HNF4A in the promoter region of EPHA1, thus promoting the deterioration of GC.

GAERF: predicting lncRNA-disease associations by graph auto-encoder and random forest

Predicting disease-related long non-coding RNAs (lncRNAs) is beneficial to finding of new biomarkers for prevention, diagnosis and treatment of complex human diseases. In this paper, we proposed a machine learning techniques-based classification approach to identify disease-related lncRNAs by graph auto-encoder (GAE) and random forest (RF) (GAERF). First, we combined the relationship of lncRNA, miRNA and disease into a heterogeneous network. Then, low-dimensional representation vectors of nodes were learned from the network by GAE, which reduce the dimension and heterogeneity of biological data. Taking these feature vectors as input, we trained a RF classifier to predict new lncRNA-disease associations (LDAs). Related experiment results show that the proposed method for the representation of lncRNA-disease characterizes them accurately. GAERF achieves superior performance owing to the ensemble learning method, outperforming other methods significantly. Moreover, case studies further demonstrated that GAERF is an effective method to predict LDAs.

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.

Research Progress and Application Prospects of Long Noncoding RNAs in Gastric Neoplasms

Long noncoding RNAs (lncRNAs) are noncoding RNAs longer than 200 nt that have almost no function for encoding proteins. As an important regulatory molecule of the human genome, lncRNAs play a regulatory role in the human body. LncRNAs have a variety of functions, such as signaling, guiding, baiting or scaffolding of functional proteins, and are closely related to tumor development. Gastric cancer is one of the most common malignant tumors. It has a high incidence, a low early diagnosis rate, and a poor prognosis, and it seriously threatens human health. Abnormal expression of lncRNAs can affect the occurrence, development, invasion and metastasis of gastric cancer. Therefore, lncRNAs are expected to become important biomarkers and new targets for the diagnosis and treatment of gastric cancer. LncRNAs have a significant potential to guide the diagnosis, treatment and prognosis of gastric cancer. This article reviews lncRNAs and the mechanisms that have been discovered in recent years related to gastrointestinal tumors.

lncRNA HOTAIR knockdown suppresses gastric cancer cell biological activities

The aim of this study was to characterize the involvement of long noncoding RNA HOTAIR in gastric cancer development. Measurement of HOTAIR and miRNA-206 expression by in situ hybridization (ISH) and analyzed for the correlation between HOTAIR and miRNA-206 in gastric cancer tissues. To evaluate the effects of HOTAIR in gastric cancer, MTT assay, flow cytometry, transwell, and wound healing assays were applied. To explain the mechanism behind HOTAIR's involvement, the expression of proteins related to it was also measured by Western blotting. Finally, correlations among related factors were determined by a luciferase target experiment. HOTAIR expression significantly increased, and miRNA-206 expression significantly decreased in cancer tissues (p < .01 and p < .001, respectively); HOTAIR knockdown suppressed cell viability, increased cell apoptosis by maintaining cells in the G1 phase, and inhibited cell invasion and migration by regulating miRNA-206 expression (p < .01 or p < .001). Meanwhile, with HOTAIR knockdown, CCND1 and CCND2 protein expressions were significantly suppressed, whereas miRNA-206 expression increased (p < .01 or p < .001). HOTAIR was shown to target miRNA-206 and miRNA-206 targeted CCND1 and CCND2. HOTAIR knockdown had antitumor effects by suppressing CCND1 and CCND2 expression by stimulating miRNA-206 in gastric cancer in vitro study.

Long Non-Coding RNA HCG11 Aggravates Osteosarcoma Carcinogenesis via Regulating the microRNA-579/MMP13 Axis

Background

Previous studies have suggested that long non-coding RNAs (lncRNAs) were involved in tumorigenesis of various human carcinomas, including osteosarcoma (OS). However, the expression and specific role of lncRNA HLA complex group 11 (HCG11) in OS remain unknown. The current study aimed at revealing the role of lncRNA HCG11 and its related mechanism in OS.

Methods

lncRNA HCG11 expression was verified with RT-qPCR followed by sub-localization determination. LncRNA-microRNA (miRNA) and miRNA–mRNA interactions were predicted by online bioinformatics websites. Validation was performed using dual-luciferase reporter gene assays, and gain- and loss-of-function experiments. The effects of lncRNA HCG11, miR-579 and matrix metalloproteinase 13 (MMP13) on the proliferation, migration and invasion, epithelial-mesenchymal transition (EMT) of OS cells were detected using cell counting kit-8 (CCK-8), Transwell assays and Western blot analysis.

Results

LncRNA HCG11 overexpression was observed in OS tissues and cell lines. Downregulation of lncRNA HCG11/MMP13 or overexpression of miR-579 blocked the progression of OS cells. LncRNA HCG11, which is located in the cytoplasm, promoted MMP13 expression through sponging miR-579.

Conclusion

LncRNA HCG11 might be beneficial for OS aggravation via sponging miR-579 and facilitating MMP13 expression, which represents a candidate biomarker and target for OS therapy.

The role of long non-coding RNAs in mediating chemoresistance by modulating autophagy in cancer

Cancer is a complex process in which protein-coding and non-coding genes play essential roles. Long noncoding RNAs (lncRNAs), as a subclass of noncoding genes, are implicated in various cancer processes including growth, proliferation, metastasis, and angiogenesis. Due to presence in body fluids such as blood and urine, lncRNAs have become novel biomarkers in cancer detection, diagnosis, progression, and therapy response. Remarkably, increasing evidence has verified that lncRNAs play essential roles in chemoresistance by targeting different signalling pathways. Autophagy, a highly conserved process in response to environmental stresses such as starvation and hypoxia, plays a paradoxical role in inducing resistance or sensitivity to chemotherapy agents. In this regard, we reviewed chemoresistance, the role of lncRNAs in cancer, and the role of lncRNAs in chemoresistance by modulating autophagy.

Dual functional nanoparticles efficiently across the blood-brain barrier to combat glioblastoma via simultaneously inhibit the PI3K pathway and NKG2A axis

The blood-brain barrier (BBB) and complex tumour immunosuppressive micro-environment posed austere challenges for combatting brain tumours such as the glioblastoma. In this study, we have developed a novel dual functional dendrimer drug delivery system (DDS) by the PAMAM and loaded with siLSINCT5 (NP- siRNA) for efficiently across the BBB to inhibit glioblastoma. To achieve the goal of BBB crossing, on the surface of NP-siRNA was decorated with the cell penetrating peptides tLyp-1 (tLypNP-siRNA). Moreover, to overcome the immunosuppressive microenvironment within the glioblastoma (GBM) tissues, a checkpoint inhibitor named as anti-NKG2A monoclonal antibody (aNKG2A), which was able of promoting anti-tumour immunity by unleashing both T and NK Cells, was further conjugated on the surface of siLSINCT5-loaded nanoparticles via the pH-sensitive linkage. Therefore, the developed dual functional and siLSINCT5-loaded dendrimer nanoparticles (tLyp/aNKNP-siRNA) was supposed to have the ability to efficiently cross the BBB and inhibit GBM by simultaneously inhibit the LSINCT5-activated signalling pathways and activate the anti-tumour immunity. The hypothesis was thoroughly confirmed by in vitro cellular and in vivo animal experiments, and provided a novel strategy for combating glioblastoma.

LncRNA NEAT1 promotes gastric cancer progression via miR-1294/AKT1 axis

Long non-coding RNAs (lncRNAs) were reported to promote the development of gastric cancer (GC). Nuclear-enriched abundant transcript 1 (NEAT1) played a great role in diverse cancers, but the mechanism of NEAT1 in GC remains indistinct. NEAT1 and AKT1 were distinctly up-regulated and miR-1294 was down-regulated in GC tissues and cells. Cell proliferation and metastasis were refrained but apoptosis was promoted in GC cells after knockdown of NEAT1. NEAT1 negatively regulated miR-1294 expression, and the miR-1294 inhibitor reverted the si-NEAT1-induced effect on GC cells. NEAT1 modulated AKT1 expression through miR-1294, and the si-NEAT1-induced effect was relieved by AKT1. NEAT1 affected phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling pathway via regulating miR-1294 and AKT1. NEAT1 could modulate cell proliferation, apoptosis, and metastasis in GC cells by regulating the PI3K/AKT/mTOR signaling pathway via the miR-1294/AKT1 axis, showing the great potential for NEAT1 as a valid biomarker in the progression and treatment of GC.

Long non-coding RNA Loc490 inhibits gastric cancer cell proliferation and metastasis by upregulating RNA-binding protein Quaking

Gastric cancer (GC) is one of the most common malignant tumor types worldwide. Long non-coding RNAs (lncRNAs) have important epigenetic effects, including altering the proliferation and metastasis of malignant tumors. We used gene chip technology to search for lncRNAs that were differentially expressed in GC and metastatic lymph node tissues compared with adjacent normal tissues. The lncRNA Loc490 and the RNA-binding protein Quaking (QKI) were downregulated in GC tissues and lymph node metastases compared with normal tissues, and the levels of these two genes correlated positively with one another. Loc490 expression correlated negatively with lymph node metastasis and vein/nerve invasion, while it correlated positively with overall and disease-free survival. In vitro, Loc490 post-translationally enhanced the expression of QKI and suppressed the expression of epithelial-mesenchymal transition-related molecules. Overexpression of Loc490 inhibited GC cell proliferation, invasion and metastasis and exerted strong antitumor effects in vivo, while silencing of QKI antagonized these effects. A potential binding site between Loc490 and QKI was detected through bioinformatics analysis and confirmed through RNA immunoprecipitation and mutant analyses. Our results suggest that lncRNA Loc490 inhibits GC cell proliferation and metastasis by upregulating RNA-binding protein QKI.

Long non-coding RNAs as potential markers for occurrence, progression, and prognosis of gastric cancer

In recent years, more and more attention has been paid to the relationship between long non-coding RNAs (lncRNAs) and tumor. Abnormal expression of lncRNAs plays an oncogenic or tumor-suppressing role in gastric cancer (GC) by participating in the biological behaviors of GC cells, such as proliferation, invasion, and migration. By summarizing the relevant literature, this paper discusses the research status, detection technology, and mechanism of action of lncRNAs in GC, as well as their potential as markers for occurrence, progression, prognosis, and drug resistance of GC. It is expected that lncRNAs can play an important role in early detection, early treatment, and effective improvement of chemotherapy resistance of GC to achieve personalized precise treatment of this malignancy.

Activation of the LINC00242/miR-141/FOXC1 axis underpins the development of gastric cancer

Background

Long non-coding RNAs (LncRNAs) are a class of newly identified transcripts recognized as critical governors of gene expression during human carcinogenesis, whereas their tumor-suppressive or tumor-promoting effects on gastric cancer (GC) are required for further investigation. In the study, we identify the expression pattern of a novel lncRNA LINC00242 in GC and its possible permissive role in the development of GC.

Methods

The study included 68 pairs of GC and adjacent normal gastric tissue samples. The viability, migration, and invasion of cultured human GC cells HGC27 were evaluated by CCK-8 and Transwell chamber assays. In vitro tube formation of human brain microvascular endothelial cells (HBMVECs) in HGC27 cell coculture was detected. The regulatory network of LINC00242/miR-141/FOXC1 was verified using dual luciferase reporter gene assay and RNA immunoprecipitation (RIP) assay. Subcutaneous xenografts of HGC27 cells were performed in nude mice.

Results

LINC00242 was highly expressed in GC tissues and cells and contributed to poor prognosis. LINC00242 knockdown inhibited HGC27 cell viability, migration and invasion, and tube formation of HBMVECs. LINC00242 interacted with miR-141 and positively regulated FOXC1, a target gene of miR-141. LINC00242 knockdown was partially lost in HGC27 cells upon miR-141 inhibition or FOXC1 overexpression. The tumor-promoting effect of LINC00242 on GC was demonstrated in nude mice.

Conclusion

Taken together, the present study demonstrates the oncogenic role of the LINC00242/miR-141/FOXC1 axis in GC, highlighting a theoretical basis for GC treatment.

Non-Coding RNAs as Potential Novel Biomarkers for Early Diagnosis of Hepatic Insulin Resistance

In the recent years, the prevalence of metabolic conditions such as type 2 Diabetes (T2D) and metabolic syndrome (MetS) raises. The impairment of liver metabolism resulting in hepatic insulin resistance is a common symptom and a critical step in the development of T2D and MetS. The liver plays a crucial role in maintaining glucose homeostasis. Hepatic insulin resistance can often be identified before other symptoms arrive; therefore, establishing methods for its early diagnosis would allow for the implementation of proper treatment in patients before the disease develops. Non-coding RNAs such as miRNAs (micro-RNA) and lncRNAs (long-non-coding RNA) are being recognized as promising novel biomarkers and therapeutic targets—especially due to their regulatory function. The dysregulation of miRNA and lncRNA activity has been reported in the livers of insulin-resistant patients. Many of those transcripts are involved in the regulation of the hepatic insulin signaling cascade. Furthermore, for several miRNAs (miR-802, miR-499-5p, and miR-122) and lncRNAs (H19 imprinted maternally expressed transcript (H19), maternally expressed gene 3 (MEG3), and metastasis associated lung adenocarcinoma transcript 1 (MALAT1)), circulating levels were altered in patients with prediabetes, T2D, and MetS. In the course of this review, the role of the aforementioned ncRNAs in hepatic insulin signaling cascade, as well as their potential application in diagnostics, is discussed. Overall, circulating ncRNAs are precise indicators of hepatic insulin resistance in the development of metabolic diseases and could be applied as early diagnostic and/or therapeutic tools in conditions associated with insulin resistance.

Overexpression of long noncoding RNA HOXA-AS2 predicts an adverse prognosis and promotes tumorigenesis via SOX4/PI3K/AKT pathway in acute myeloid leukemia

Long noncoding RNAs (lncRNAs) play important roles in diverse cellular processes and carcinogenesis. Homeobox A cluster antisense RNA 2 (HOXA-AS2) is a 1,048-basepairs lncRNA located between human HOXA3 and HOXA4 genes, whose overactivation was previously found to promote the proliferation and invasion of solid tumors. However, its clinical and biological roles in acute myeloid leukemia (AML) remain unclear. This study showed that HOXA-AS2 was overexpressed in AML patients. In addition, the increased HOXA-AS2 expression was correlated with higher white blood cell and bone marrow blast counts, unfavorable karyotype classification, more measurable residual disease positivity, and earlier death. There was also a tendency toward inferior survival in patients with high HOXA-AS2 expression, and HOXA-AS2 was an independent prognostic factor among the normal-karyotype AMLs. Furthermore, the results of in vitro study showed that silencing HOXA-AS2 significantly inhibited the growth of leukemic cells by inducing G1/G0-phase arrest and apoptosis. Further analysis demonstrated that silencing HOXA-AS2 suppressed the phosphorylation level of PI3K and AKT, which thereafter promoted the expression of P21 and P27. Moreover, it was suggested that the sex-determining region Y-box 4 (SOX4), which is closely involved in the PI3K/AKT pathway, might be one of the major downstream targets of HOXA-AS2. Silencing HOXA-AS2 decreased the expression of SOX4, whereas the upregulation of SOX4 partially abrogated the inhibitory effect of silencing HOXA-AS2 on leukemic cells. In conclusion, these findings suggest that HOXA-AS2 probably functions as an oncogene via SOX4/PI3K/AKT pathway and might be a useful biomarker for the prognostic prediction in AML patients, providing a potential therapeutic target for AML.

Integrative analysis of immune microenvironment-related CeRNA regulatory axis in gastric cancer

This study aimed to identify significant immune microenvironment-related competing endogenous RNA (CeRNA) regulatory axis in gastric cancer (GC). Analysis of differentially expressed mRNAs (DEmRNAs), miRNAs (DEmiRNAs), and lncRNAs (DElncRNAs) was performed for the microarray datasets. After abundance analysis of immune cell's infiltration, immune-related mRNAs and lncRNAs were obtained. Meanwhile, according to the Pearson correlation coefficient between immune-related mRNAs and lncRNAs, the co-expression mRNA-lncRNA pairs were screened. Furthermore, the target genes of co-existance miRNAs were predicted, and miRNA-lncRNA pairs were identified. Finally, the lncRNA-miRNA and miRNA-mRNA relationship regulated by the same miRNA was screened. Combining with the co-expression relationship between lncRNA and mRNA, the CeRNA network was constructed. In abundance analysis of immune cell's infiltration, a total of eight immune cells were obtained, in addition, 83 immune-related DElncRNAs and 705 immune-related DEmRNAs were screened. KEGG pathway enrichment analysis showed that these mRNAs were mainly involved in PI3K-Akt signaling pathway and human papillomavirus infection, while lncRNA were relevant to gastric acid secretion. A total of 25 miRNAs were significantly associated with immune-related mRNAs, such as hsa-miR-148a-3p, hsa-miR-17-5p, and hsa-miR-25-3p. From the mRNA-miRNA-lncRNA CeRNA network, we observed that AC104389.28─miR-17-5─SMAD5 axis and LINC01133─miR-17-5p─PBLD axis played a crucial role in the development of GC. Furthermore, resting memory CD4 T cells and plasma cells were closely associated with the pathogenesis of GC, and these immune cells might be affected by the key genes. The present study identified key genes that associated with immune microenvironment in GC, providing potential molecular targets for immunotherapy of GC.

Interaction between ACOT7 and LncRNA NMRAL2P via Methylation Regulates Gastric Cancer Progression

PURPOSE

Gastric cancer (GC) has a very poor prognosis when diagnosed at a late stage. Acyl-CoA thioesterase 7 (ACOT7) is a major isoform of the acyl coenzyme family that catalyzes the hydrolysis of fatty acyl-CoAs into unesterified free fatty acid and coenzyme A. The purpose of this study was to investigate the expression levels of ACOT7 in GC and mechanisms related therewith.

MATERIALS AND METHODS

Screening of systematic biology studies revealed ACOT7 as a key gene in GC, as well as involvement of the long non-coding RNA NMRAL2P in ACOT7 expression. In this study, GC tissues and adjacent tissue samples were obtained from 10 GC patients at the Department of Gastrointestinal Surgery. GES1 and SGC-7901 cells were collected and treated to silence ACOT7 and overexpress NMRAL2P. The expressions of ACOT7 and NMRAL2P were detected by real-time quantitative PCR and Western blot. Additionally, cell proliferation, apoptosis, migration, and invasion were examined.

RESULTS

ACOT7 was upregulated in gastric tumor tissues and GC cell lines. ACOT7 gene silencing induced a less malignant phenotype and was closely correlated to reduced cell proliferation and migration, altered cell cycle, and increased apoptosis. Furthermore, NMRAL2P was downregulated in tumor tissues and GC cell lines. NMRAL2P overexpression induced a more malignant phenotype and significantly inhibited the expression of ACOT7. Importantly, NMRAL2P indirectly methylated ACOT7 by binding to DNMT3b, thereby suppressing ACOT7 expression.

CONCLUSION

NMRAL2P activation suppresses ACOT7 expression in GC. Thus, ACOT7 could be a promising target for the treatment of GC.

The Effect of Long Non-Coding RNA (lncRNA) HCP5 on Regulating Epithelial-Mesenchymal Transition (EMT)-Related Markers in Gastric Carcinoma Is Partially Reversed by miR-27b-3p

Background

lncRNA HCP5 plays a cancer-promoting role in a variety of cancers. This study was the first to explore the mechanism of HCP5 in gastric carcinoma (GC).

Material/Methods

The differences in HCP5 between GC patients and healthy people were revealed in the TCGA database. The expression of HCP5 in GC tissues and adjacent tissues was compared by qRT-PCR. At the same time, the clinic pathological features of the patients were counted. Starbase and luciferase assay predicted and verified that miR-27b-3p is a targeted miRNA for HCP5. The expression of HCP5 and miR-27b-3p in various GC cells was detected by qRT-PCR. Cell viability and metastasis in different treatment groups were assessed by use of Cell Couting Kit-8 assay and clone formation assay, wound-healing assay, and transwell assay. Finally, expression of epithelial-mesenchymal transition (EMT)-associated markers was detected by Western blot.

Results

We found that HCP5 was overexpressed in GC tissues. Patients with higher expression of HCP5 had larger tumors, were more likely to have lymph node metastasis, and had higher TNM stage. HCP5 was overexpressed in GC cells, but this was reversed by miR-27b-3p. Silencing HCP5 inhibited GC cell viability and metastasis by downregulating Vimentin and N-cadherin and up-regulating E-cadherin, but this effect was partially reversed by miR-27b-3p inhibitor.

Conclusions

The effect of silencing HCP5 on repressing GC cells viability and metastasis by regulating EMT-associated markers can be partially reversed by miR-27b-3p inhibitor.

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.

LncRNA COL1A1-014 is involved in the progression of gastric cancer via regulating CXCL12-CXCR4 axis

BACKGROUND

The aberrant expression of long noncoding RNAs (lncRNAs) is found in various types of cancers and also showed its association with the occurrence and development of gastric cancer (GC). We found lncRNA COL1A1-014 was frequently upregulated in GC.

METHODS

This study investigated COL1A1-014 for its biological function at both cellular and animal levels, using MTT, flow cytometry, colony formation and transwell assays. The expression levels of COL1A1-014 and other genes were detected by RT-PCR and western blot. Luciferase reporter assay was used to detect the potential binding of miR-1273h-5p to COL1A1-014 and CXCL12.

RESULTS

We found that COL1A1-014 was frequently upregulated in GC tissues as well as cells. COL1A1-014 increased cell proliferation, colony forming efficiency, migration ability, invasion ability, and weight and volume of grafted tumors, while reduced cell apoptosis. Overexpression of COL1A1-014 increased the mRNA expression of chemokine (CXCmotif) ligand (CXCL12) and high levels of CXCL12 and CXCR4 proteins in GC cells. The levels of miR-1273h-5p showed an inverse correlation with COL1A1-014 and CXCL12 in GC cells transfected with miR-1273h-5p. The mRNAs of wild-type COL1A1-014 and CXCL12 showed reduction in HEK293 cells transfected with miR-1273h-5p. This suggested that COL1A1-014 functions as an efficient miR-1273h-5p sponge and as a competing endogenous RNA (ceRNA) to regulate CXCL12. The proliferative activity of COL1A1-014 on GC cells was blocked by CXCL12-CXCR4 axis inhibitor AMD-3100.

CONCLUSIONS

These findings demonstrated that COL1A1-014 play an important regulatory role in GC development by functioning as a ceRNA in regulating the CXCL12/CXCR4 axis via sponging miR-1273h-5p.

A Review of Research Progress in Multidrug-Resistance Mechanisms in Gastric Cancer

Gastric cancer is one of the most common malignant tumors, and it is also one of the leading causes of cancer death worldwide. Because of its insidious symptoms and lack of early dictation screening, many cases of gastric cancer are at late stages which make it more complicated to cure. For these advanced-stage gastric cancers, combination therapy of surgery, chemotherapy, radiotherapy and target therapy would bring more benefit to the patients. However, the drug-resistance to the chemotherapy restricts its effect and might lead to treatment failure. In this review article, we discuss the mechanisms which have been found in recent years of drug resistance in gastric cancer. And we also want to find new approaches to counteract chemotherapy resistance and bring more benefits to the patients.

Identification of the Prognosis-Related lncRNAs and Genes in Gastric Cancer

Gastric cancer is a common malignant tumor with high occurrence and recurrence and is the leading cause of death worldwide. However, the prognostic value of protein-coding and non-coding RNAs in stage III gastric cancer has not been systematically analyzed. In this study, using TCGA data, we identified 585 long noncoding RNAs (lncRNAs) and 927 protein-coding genes (PCGs) correlated with the overall survival rate of gastric cancer. Functional enrichment analysis revealed that the prognostic genes positively correlated with death rates were enriched in pathways, including gap junction, focal adhesion, cell adhesion molecules (CAMs), and neuroactive ligand-receptor interaction, that are involved in the tumor microenvironment and cell-cell communications, suggesting that their dysregulation may promote the tumor progression. To evaluate the performance of the prognostic genes in risk prediction, we built three multivariable Cox models based on prognostic genes selected from the prognostic PCGs and lncRNAs. The performance of the three models based on features from only PCGs or lncRNAs or from all prognostic genes were systematically compared, which revealed that the features selected from all the prognostic genes showed higher performance than the features selected only from lncRNAs or PCGs. Furthermore, the multivariable Cox regression analysis revealed that the stratification with the highest performance was an independent prognostic factor in stage III gastric cancer. In addition, we explored the underlying mechanism of the prognostic lncRNAs in the Cox model by predicting the lncRNA and protein interaction. Specifically, CTD-2218G20.2 was predicted to interact with PSG4, PSG5, and PSG7, which could also interact with cancer-related proteins, including KISS1, TIMP2, MMP11, IGFBP1, EGFR, and CDKN1C, suggesting that CTD-2218G20.2 might participate in the cancer progression via these cancer-related proteins. In summary, the systematic analysis of the prognostic lncRNAs and PCGs was of great importance to the understanding of the progression of stage III gastric cancer.

Long non-coding RNA ERICH3-AS1 is an unfavorable prognostic factor for gastric cancer

Long non-coding RNAs (lncRNAs) play important roles in gastric cancer (GC), but the mechanism is not fully clear. ERICH3-AS1 (ERICH3 antisense RNA1) is affiliated with the non-coding RNA class which has proven to be involved in the prognostic of GC, but the function of ERICH3-AS1 is still unclear. In this study, we aim to explore the potential function of ERICH3-AS1 in the development of GC and analyze the prognostic role of ERICH3-AS1 in GC. We found that the lncRNA ERICH3-AS1 was significantly up-regulated in GC tissues in the analysis of The Cancer Genome Atlas (TCGA) data; the Kaplan-Meier analysis showed that the higher the expression of ERICH3-AS1 was, the earlier the recurrence and the poorer the prognosis would be in patients. Cox univariate and multivariate analyses revealed that ERICH3-AS1 was a risk factor of disease-free survival (DFS) (p < 0.05) and overall survival (OS) (p < 0.05) of patients. Through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, it demonstrated that the ERBB pathways, the mitogen-activated protein kinase (MAPK) pathways, the MTOR pathways, p53 pathways and Wnt pathways were differentially enriched in ERICH3-AS1 high expression phenotype. Furthermore, the correlation analysis showed that ERICH3-AS1 had significant correlations with apoptosis-related proteins such as BCL2L10 and CASP14; cell cycle-associated proteins CDK14 and invasion and migration-associated proteins such as MMP20, MMP26 and MMP27. In summary, we identified that increased ERICH3-AS1 might be a potential biomarker for diagnosis and independent prognostic factor of GC. Moreover, ERICH3-AS1 might participate in the oncogenesis and development of tumors via cell cycle and apoptosis pathway mediated by ERBB, MAPK, MTOR, p53 and Wnt pathways.

Expression levels and associations of five long non-coding RNAs in gastric cancer and their clinical significance

Gastric cancer (GC) is a type of cancer that is commonly diagnosed worldwide due to a lack of early diagnostic, prognostic and therapeutic targets for this disease. The aim of the present study was to examine the expression levels of five long non-coding RNAs, namely PTPRG antisense RNA 1 (PTPRG-AS1), forkhead box P4 antisense RNA 1 (FOXP4-AS1), bladder cancer-associated transcript 2 (BLACAT2), ZXF2 and upregulated in colorectal cancer (UCC), to study their associations with patient characteristics and assess their prognostic efficacy, in order to determine the possibility of their application as GC biomarkers. The expression levels of long non-coding RNAs (lncRNAs) were determined by reverse transcription-quantitative PCR analysis of 61 pairs of GC tissues and adjacent healthy gastric mucosa tissues and GC cell lines. The Chi-square test was conducted to assess the associations of lncRNA expression levels with clinical characteristics of patients. The effect of UCC on GC cell proliferation was determined using in vitro functional experiments. The prognostic efficacy of FOXP4-AS1, BLACAT2 and UCC were examined in the Gene Expression Profiling Interactive Analysis database and those of PTPRG-AS1 were examined in the Kaplan Meier Plot database. Gene alteration frequencies of PTPRG-AS1 and BLACAT2 in GC were identified using the cBioPortal for Cancer Genomics. PTPRG-AS1, FOXP4-AS1, BLACAT2, ZXF2 and UCC were found to be upregulated in GC cell lines and GC tissues compared with adjacent normal tissues. PTPRG-AS1 and ZXF2 expression levels were associated with the expression status of the cell proliferation marker Ki67. UCC promoted the proliferation of GC cells in vitro and was associated with lymph node metastasis. Increased expression of FOXP4-AS1 indicated a favorable outcome in terms of disease-free survival, whereas high expression of PTPRG-AS1 was associated with poor survival rates for patients in different GC risk groups. BLACAT2 gene mutation was associated with poor disease-free survival outcome for patients with GC. The results suggest that PTPRG-AS1, FOXP4-AS1, BLACAT2, ZXF2 and UCC are potential biomarkers for the detection of GC at the molecular level and may be used as potential targets for GC therapy. The individual roles of these lncRNAs may be utilized for prognostic predictions.

Silencing of Long Non-Coding RNA Colon Cancer-Associated Transcript 2 Inhibits the Growth and Metastasis of Gastric Cancer Through Blocking mTOR Signaling

Purpose

This study aimed to evaluate the specific role of colon cancer-associated transcript 2 (CCAT2) on gastric cancer (GC), and reveal the potential regulatory mechanism relating to mammalian target of rapamycin (mTOR) signaling.

Methods

The expression of CCAT2 was detected in GC tissues and cells by quantitative real-time PCR (qRT-PCR), and its relation with the pathologic characteristics of GC patients was analyzed. HGC-27 and SGC-7901 cells were transfected with siRNA-CCAT2 to silence CCAT2, and HGC-27 cells were then treated with an mTOR agonist Leucine (Leu) to activate mTOR signaling. The cell proliferation was evaluated by cell viability and colony formation. The cell cycle and apoptosis, and the migration and invasion abilities were detected by Flow cytometry, and Transwell assay, respectively. The expression of PCNA (proliferation marker), Snail, N-cadherin, E-cadherin (invasion markers), P53, Caspase-8, Bcl-2 (apoptosis markers), LC3-II/LC3-I, ATG3, p62 (autophagy makers), phosphorylated mTOR (p-mTOR), p-AKT, and p-p70S6K (mTOR signaling markers) were detected by Western blot.

Results

CCAT2 was upregulated in GC tissues and cells, and positively associated with the maximum tumor diameter, lymphatic metastasis, TNM staging, and low overall survival rate (P < 0.05). siRNA-CCAT2 transfection significantly inhibited the viability, colony formation, and migration and invasion abilities, blocked the cell cycle in G0/G1 phase, and promoted the apoptosis and autophagy of SGC-7901 and HGC-27 cells (P < 0.05). In addition, siRNA-CCAT2 transfection significantly upregulated P53, Caspase-8, LC3-II/LC3-I and ATG3, and downregulated PCNA, Bcl-2, p62, p-mTOR, p-AKT and p-p70S6K in SGC-7901 and HGC-27 cells (P < 0.05). siRNA-CCAT2 reversed the tumor-promoting effect of mTOR signaling activation on HGC-27 cells (P < 0.05).

Conclusion

Silencing of CCAT2 inhibited the proliferation, migration and invasion, and promoted the apoptosis and autophagy of GC cells through blocking mTOR signaling.