A2M promotes the progression of STAD by upregulating vimentin expression and epithelial-mesenchymal transition: boinformatics analysis and experimental verification

<h4>Background</h4>Stomach adenocarcinoma (STAD) is a common malignant tumor within the digestive system, characterized by significant morbidity and mortality rates. The identification of innovative biomarkers or therapeutic targets for STAD is of utmost importance. A deeper understanding of the molecular mechanisms underlying STAD progression may facilitate the identification of novel prognostic indicators and therapeutic strategies. This investigation aims to assess the expression patterns of alpha-2-macroglobulin (A2M) across various tumors and their corresponding pathological stages, utilizing data from The Cancer Genome Atlas (TCGA) and University of Alabama at Birmingham Cancer Analysis Portal (UALCAN) databases.<h4>Methods</h4>To evaluate the influence of A2M on survival prognosis, we employed the Kaplan-Meier method alongside Cox and receiver operating characteristic (ROC) analysis. Additionally, Tumor Immune Estimation Resource, Version 2 (TIMER2.0) was utilized to examine its impact on the infiltration of immune cells within tumors. By employing R programming, STAD samples were divided into high-expression and low-expression groups based on A2M gene expression levels. Differentially expressed genes (DEGs) were subsequently identified, followed by enrichment analyses, including Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and gene set enrichment analysis (GSEA). We further selected STAD cells exhibiting high A2M expression and utilized CRISPR/Cas9 technology to silence A2M, to investigate its effects on cell viability, migration, invasion, and colony formation capabilities.<h4>Results</h4>Bioinformatics analysis indicated that A2M is highly expressed in STAD tumor tissues compared to normal gastric tissues. Patients exhibiting elevated A2M levels experienced shorter survival periods compared to those with lower expression levels, with Cox and ROC analyses suggesting A2M's potential as a prognostic biomarker. This implies that A2M plays a role in promoting STAD progression and functions as an oncogene. Pathway enrichment analyses demonstrated that A2M facilitates epithelial-mesenchymal transition (EMT) in STAD cells, showing a significant correlation with EMT marker vimentin and EMT-related genes. Furthermore, A2M exhibited a positive correlation with the infiltration of various immune cells in STAD tissues, displaying strong associations with multiple immune cell markers. A2M expression also influences the responsiveness of STAD patients to immunotherapy and small-molecule drug therapies. Cell experiments indicated that the silencing of A2M expression led to reduced STAD cell viability, migration, invasion, and colony formation, alongside a decrease in the expression of the mesenchymal marker vimentin.<h4>Conclusions</h4>These findings suggest that A2M promotes EMT through the upregulation of vimentin expression, thereby facilitating the malignant progression of STAD. Thus, A2M emerges as a promising therapeutic target that warrants further investigation to refine treatment strategies and improve patient outcomes in STAD.