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Background and Aim: Long noncoding RNA TRPM2‐AS has emerged as a novel regulator in cancer initiation and progression of various cancers. However, the function and underlying mechanism of TRPM2‐AS in the progression of gastric cancer (GC) remain poorly understood. Methods: GEO and TCGA databases were used for isolation of differential lncRNA expression. TRPM2‐AS expression levels in GC tissues and cells were measured by quantitative polymerase chain reaction method. TRPM2‐AS subcellular location was detected by fluorescence in situ hybridization analysis. The functional roles of TRPM2‐AS in cells were analyzed by loss and gain function assays. Results: By using bioinformatics and quantitative polymerase chain reaction methods, TRPM2‐AS expression levels were proved to be upregulated in GSE70880 dataset, TCGA database, and 26 GC tissues, which was partly induced by SP1. The results of clinical assays showed that TRPM2‐AS could be an indicator for early‐stage GC diagnosis. Fluorescence in situ hybridization analysis showed that TRPM2‐AS was located in both nucleus and cytoplasm. Functional experiments displayed that knockdown of TRPM2‐AS inhibited proliferation, migration, and invasion in GC cells. Furthermore, depression of TRPM2‐AS suppressed cell growth though promotion of cell apoptosis. The expression levels of cleaved PARP, caspase 9, caspase 3, and Bax were significantly increased in BGC823 with TRPM2‐AS knockdown. In addition, knockdown of TRPM2‐AS reduced and phosphorylate signal transducer and activator of transcription 3 and increased and phosphorylate p38 mitogen‐activated protein kinase. Conclusions: This study demonstrated that SP1‐regulated TRPM2‐AS is involved in GC cell apoptosis probably via p38 mitogen‐activated protein kinase and signal transducer and activator of transcription 3 pathways, indicating that TRPM2‐AS might be a potential therapeutic target in GC. [ABSTRACT FROM AUTHOR]

Integrated analysis of accumulated data is an effective way to obtain reliable potential diagnostic molecular in gastric cancer (GC). The study aimed to identify potential lncRNAs associated with the pathogenesis and prognosis in GC. Raw noncoding RNA microarray data (GSE53137, GSE95667, and GSE111762) was downloaded from Gene Expression Omnibus (GEO) database. Differentially expressed genes between GC and adjacent normal gastric tissue samples were screened by an integrated analysis of multiple gene expression profile after gene reannotation and batch normalization. Differentially expressed genes were further confirmed by the cancer genome atlas (TCGA) database. Competing endogenous RNA (ceRNA) network, survival analysis, and gene set enrichment analysis (GSEA) were extensively applied to identify hub lncRNAs and discover potential biomarkers related to diagnosis and prognosis of GC. qPCR was applied to confirm hub lncRNA expression levels in GC tissues. In total, 17 integrated differential lncRNAs were obtained after intersections of differential genes between GEO and TCGA database. Four lncRNAs (HMGA1P4, UBE2Q1-AS1, MAGI2-AS3, MIR22HG) concentrated in ceRNA network were validated by qPCR in GC tissues, which were consistent with informatics results. The clinicopathological association revealed that four lncRNAs might be effective in GC progression. Further study revealed that GC patients with lower MAGI2-AS3 expression was evidently longer than those with higher MAGI2-AS3 expression (p = 0.015). Multivariate analysis revealed MAGI2-AS3 was independently associated with overall survival in GC. GSEA showed GC samples were differentially enriched in pyrimidine metabolism, RNA degradation, cell cycle, oxidative phosphorylation etc., and most significantly enriched in ribosome pathway in MAGI2-AS3 low expression phenotype. Four lncRNAs, including HMGA1P4, UBE2Q1-AS1, MAGI2-AS3, and MIR22HG may contribute to GC development, and MAGI2-AS3 might be associated with the prognosis of GC. [ABSTRACT FROM AUTHOR]

Gastric cancer (GC) is a common type of cancer, and identification of novel diagnostic biomarkers associated with this disease is important. The present study aimed to identify novel diagnostic biomarkers associated with the prognosis of GC, using an integrated bioinformatics approach. Differentially expressed long non-coding RNAs (lncRNAs) associated with GC were identified using Gene Expression Omnibus datasets (GSE58828, GSE72305 and GSE99416) and The Cancer Genome Atlas database. A competing endogenous RNA network that incorporated five lncRNAs [long intergenic non-protein coding RNA 501 (LINC00501), LINC00365, SOX21 antisense divergent transcript 1 (SOX21-AS1), GK intronic transcript 1 (GK-IT1) and DLEU7 antisense RNA 1 (DLEU7-AS1)], 29 microRNAs and 114 mRNAs was constructed. Gene Ontology and protein-protein interaction network analyses revealed that these lncRNAs may be involved in 'biological regulation', 'metabolic process', 'cell communication', 'developmental process', 'cell proliferation', 'reproduction' and the 'cell cycle'. The results of receiver operating characteristic curve analysis demonstrated that LINC00501 (AUC=0.819), LINC00365 (AUC=0.580), SOX21-AS1 (AUC=0.736), GK-IT1 (AUC=0.823) and DLEU7-AS1 (AUC=0.932) had the potential to become valuable diagnostic biomarkers for GC. Associations with clinicopathological characteristics demonstrated that LINC00501 expression was significantly associated with sex (P=0.015) and tumor grade (P=0.022). Furthermore, LINC00365 expression was significantly associated with lymph node metastasis (P=0.025). Gene set enrichment analysis revealed that LINC00501, LINC00365 and SOX21-AS1 were enriched in signaling pathways associated with GC. Reverse transcription-quantitative PCR analysis demonstrated that LINC00501 expression (P=0.043) was significantly upregulated in GC tissues, whereas the expression levels of LINC00365 (P=0.033) and SOX21-AS1 (P=0.037) were significantly downregulated in GC tissues. Taken together, the results of the present study suggest that LINC00501, LINC00365, SOX21-AS1, GK-IT1 and DLEU7-AS1 may be used as novel diagnostic biomarkers for GC, and may be functionally associated with GC development and progression. [ABSTRACT FROM AUTHOR]