APOA1 promotes tumor proliferation and migration and may be a potential pan-cancer biomarker and immunotherapy target

Introduction: Aberrant expression of APOA1 has been reported in various cancers. However, a comprehensive investigation into its role in cancer is currently lacking. Methods: Online websites and databases such as TIMER2.0, GEPIA2, UALCAN and GSCA were used to investigate the relationship between APOA1 expression and prognostic value, immune infiltration, gene mutations, and drug sensitivity. In addition, in vitro CCK-8 and transwell migration and invasion assays were performed to determine the biological functions of APOA1 in gastric cancer (GC) cells. Results: The pan-cancer analysis showed that APOA1 is differentially expressed in different cancer types and significantly correlated with tumor stages. A survival analysis revealed that APOA1 predicted a poor prognosis in ACC, KIRC, STAD, and a good prognosis in BRCA, OV, and UCEC. We also found that the most common genetic alteration type of APOA1 was deep deletion, and the DNA methylation level of APOA1 decreased in various cancers. Furthermore, APOA1 expression negatively correlated with immune cells infiltration in cancers, including CD4+ T, CD8+ T, and myeloid dendritic cells. For STAD, GO/KEGG enrichment analysis revealed the possible involvement of APOA1 in cholesterol metabolism and PPAR signaling pathway. Finally, we further performed in vitro experiments to verify that overexpression of APOA1 could promote the proliferation, migration and invasion of GC cells. Conclusion: The results of this study indicate that APOA1 is a potential tumor prognostic biomarker and immunotherapy target. In addition, APOA1 plays an essential role in the proliferation, migration, and invasion of GC cells by vitro experiments.