Expression, Clinical Significance, and Role in Immunotherapy Efficacy Evaluation of the Co-stimulatory Molecule LLT1 in Gastric Cancer

After a thorough examination of the TCGA and Tumor IMmune Estimation Resource(TIMER) databases, we investigated how LLT1 behaves in different types of cancer, especially gastric cancer. The TISIDB database was utilized to investigate the correlation between LLT1 expression levels and different molecular subtypes of gastric cancer.The correlation between patients' clinical characteristics and LLT1 expression was further analyzed with TCGA data through R programming. GO and KEGG analyses were employed to investigate the functional role of LLT1 in gastric carcinogenesis.The ESTIMATE (Estimation of STromal and Immune cells in MAlignant Tumor tissues using Expression data) algorithm was additionally employed to quantify immune and stromal cell infiltration levels in tumor tissues according to LLT1 expression patterns. Further analysis utilizing the CIBERSORT algorithm was conducted to evaluate correlations between LLT1 expression levels and specific immune cell infiltration patterns within the tumor microenvironment. Comprehensive bioinformatic analysis was performed using TCGA datasets and R statistical programming (v4.4.1) to interrogate potential correlations between LLT1 expression profiles and immunoregulatory biomarkers. Finally, the TCIA (The Cancer Immunome Atlas) database was utilized to investigate whether LLT1 expression could predict response to PD-1/PD-L1 immune checkpoint blockade therapy.