Gastric cancer (GC) is the fourth most common malignant tumor. The mechanism underlying GC occurrence and development remains unclear. Previous studies have indicated that long non-coding RNAs (lncRNAs) are significantly associated with gastric cancer, but a systematic understanding of the role of lncRNAs in gastric cancer is lacking. In recent years, with the development of next-generation sequencing technology, tens of thousands of lncRNAs have been discovered. However, a large number of unannotated lncRNAs remain unidentified in different tissues, including potential gastric cancer-related lncRNAs. In this study, RNA sequencing (RNA-seq) data from 16 samples of eight gastric cancer patients were obtained and analyzed. A total of 1,854 previously unannotated lncRNAs were identified by ab initio assembly, and 520 differentially expressed lncRNAs were validated in the TCGA expression dataset. Methylation and copy number variation (CNV) array data from the same sample were integrated in the analysis. Changes in DNA methylation levels and CNVs may be responsible for the differential expression of 91 lncRNAs. Differentially expressed lncRNAs were enriched in coexpressed clusters of genes related to functions such as cell signaling, cell cycle, immune response, metabolic processes, angiogenesis, and regulation of retinoic acid (RA) receptors. Finally, a differentially expressed lncRNA, AC004510.3, was identified as a potential biomarker for the prediction of the overall survival of gastric cancer patients.

胃癌（GC）是第四大最常见的恶性肿瘤。GC发生和发展的潜在机制尚不清楚。先前的研究表明，长的非编码RNA（lncRNA）与胃癌显着相关，但对lncRNA在胃癌中的作用缺乏系统的了解。近年来，随着下一代测序技术的发展，已经发现了数以万计的lncRNA。然而，在许多不同的组织中，包括潜在的胃癌相关的lncRNA，许多未注释的lncRNA仍然未被鉴定。在这项研究中，获得并分析了来自8位胃癌患者的16个样品的RNA测序（RNA-seq）数据。总共鉴定出1,854个先前未注释的lncRNA。从头开始装配，并在TCGA表达数据集中验证了520个差异表达的lncRNA。来自同一样品的甲基化和拷贝数变异（CNV）阵列数据已整合到分析中。DNA甲基化水平和CNV的变化可能是91个lncRNA差异表达的原因。差异表达的lncRNA富含共表达的与功能有关的基因簇，这些功能与细胞信号传导，细胞周期，免疫应答，代谢过程，血管生成和视黄酸（RA）受体的调节有关。最后，鉴定出差异表达的lncRNA AC004510.3作为预测胃癌患者总体生存的潜在生物标志物。