Bioinformatics analysis combined with cell experiments reveals that APOC1 inhibits ferroptosis and promotes M2 macrophage polarization by activating the PI3K/AKT signaling pathway in oral squamous cell carcinoma cells.

BACKGROUND: Oral squamous cell carcinoma (OSCC) is the most common malignant tumor in the head and neck region. Apolipoprotein C1 (APOC1) has been identified as an oncogene in multiple tumors, while its role and molecular mechanism in OSCC remain incompletely understood. METHODS: Data of primary and metastatic OSCC samples were downloaded from GSE275870 dataset, and ferroptosis-related genes were retrieved from FerrDb V2 database. Clustering analysis was performed on 108 OSCC samples from GSE275870 dataset using 29 ferroptosis-related genes to identify molecular subtypes. Differentially expressed genes (DEGs) were analyzed, and machine learning algorithms were utilized to screen core genes. Immune and ferroptosis correlation analysis was conducted by Spearman correlation coefficient. Western blotting was performed for protein detection. Cell viability was examined using cell counting kit-8 assay. Ferroptosis-associated markers were evaluated using commercial kits. Cluster of differentiation 206 (CD206) and CD86 rates in THP1-0 macrophages were examined using flow cytometry. Enzyme-linked immunosorbent assay was employed to measure M2 and M1 macrophage markers. Cell migration was assessed using transwell assay. RESULTS: Clustering analysis identified two molecular types (C1 and C2) related to ferroptosis. Differential analysis and machine learning screened APOC1 as a key gene, and it was highly expressed in C1 and metastasis samples (P < 0.05). APOC1 was significantly correlated to M2 macrophage polarization and ferroptosis (P < 0.05). APOC1 downregulation enhanced ferroptosis of OSCC cells (lipid ROS increased ∼3-fold; GSH decreased ∼50%), inhibited M2 macrophage polarization (CD206 + cells reduced ∼2-fold) and promoted M1 macrophage polarization (CD86 + cells increased ∼2-fold) (P < 0.05). APOC1 knockdown inactivated the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway (p-AKT/AKT reduced ∼66%) to promote ferroptosis and inhibit M2 macrophage polarization, thus preventing OSCC cell migration (P < 0.05). CONCLUSION: This study integrates bioinformatics and in vitro experiments to demonstrate that APOC1 suppresses ferroptosis and promotes M2 macrophage polarization in the OSCC microenvironment by activating the PI3K/AKT pathway. Beyond confirming APOC1's known anti-ferroptosis role, our study reveals its crucial function in lymph node metastasis-associated molecular subtyping and tumor-macrophage crosstalk, highlighting a potential dual-targeting strategy for OSCC intervention.