Bioinformatic Analysis and Experimental Validation of HMGA2-AS1 as a Prognostic Biomarker Associated with Immune Infiltration in Gastric Cancer

Background: Natural antisense long noncoding RNAs (lncRNAs) have the ability to modulate the expression of their corresponding sense genes. Consequently, any dysregulation of these lncRNAs can contribute to the development of pathological processes. The ambiguity surrounding the role of HMGA2-AS1 in gastric cancer (GC) requires further investigation. Objective: The aim of this study was to examine the involvement of HMGA2-AS1 in GC. Methods: The Kaplan-Meier method, Cox regression analysis, gene set enrichment analysis (GSEA), and immune infiltration analysis were used in this study. These methods were used to evaluate the relationship between clinical characteristics and HMGA2-AS1 expression, prognostic factors, and the significant functional impact of HMGA2-AS1. HMGA2-AS1 levels in GC cell lines were validated using quantitative real-time polymerase chain reaction (qRT-PCR). Results: In patients diagnosed with GC, a significant correlation was observed between high expression of HMGA2-AS1 and the T stage (p = 0.01). Furthermore, the high expression of HMGA2- AS1 was identified as a prognostic indicator for poorer OS (p = 0.004), PFS (p = 0.006), and DSS (p = 0.011). Furthermore, the expression of HMGA2-AS1 (p < 0.001) demonstrated an independent association with OS in patients with GC. The presence of a low expression phenotype of HMGA2-AS1 was associated with differential enrichment of various pathways, including the focal adhesion-PI3K-Akt-mTOR signaling pathway, focal adhesion, ECM glycoproteins, MET promoting cell motility, among others. Furthermore, the expression of HMGA2-AS1 exhibited correlations with B cells, CD56 bright cells, and TFH and Th17 cells. Furthermore, GC cell lines demonstrated significantly higher expression of HMGA2-AS1. Conclusion: Elevated expression of HMGA2-AS1 in GC patients exhibited a significant correlation with unfavorable survival outcomes and increased immune infiltration. This suggests that HMGA2- AS1 holds promise as a potential prognostic biomarker and target for immunotherapy in GC.