HNRNPA1-mediated upregulation of SLC3A2 modulates cuproptosis-associated phenotypes and cell viability in RA-FLS

Rheumatoid arthritis (RA) is characterized by persistent synovial inflammation and the abnormal survival of fibroblast-like synoviocytes (FLS). Although m6A RNA modification and cuproptosis have both been implicated in cell-fate regulation, their potential functional connection in RA-FLS remains unclear. This study aimed to identify m6A-associated regulators linked to cuproptosis-related phenotypes in RA and to characterize the HNRNPA1-SLC3A2 regulatory relationship and its biological relevance. This study integrated bioinformatics with multi-dimensional experimental validation. First, weighted gene co-expression network analysis (WGCNA), differential expression analysis, and receiver operating characteristic (ROC) curve analysis were performed on the GSE55235 dataset to evaluate the discriminatory performance of the candidate genes. The m6A2Target database was used to predict the upstream m6A regulators. qPCR, Western blot, CCK-8, transmission electron microscopy, and m6A-RIP-qPCR were performed to verify the results in RA-FLS. Immune cell infiltration analysis was performed using CIBERSORT. Four key cuproptosis-related genes were identified, among which SLC3A2 was the most significantly downregulated gene and showed the highest discriminatory performance within the GSE55235 dataset (AUC = 0.98). Experimentally, HNRNPA1 overexpression increased SLC3A2 expression without detectably altering the m6A enrichment of SLC3A2 mRNA. Functional experiments showed that HNRNPA1 overexpression modulated cuproptosis-associated molecular and biochemical features, increased LDH release, and reduced RA-FLS viability. SLC3A2 knockdown aggravated these abnormalities, whereas HNRNPA1 overexpression partially reversed the changes induced by SLC3A2 deficiency. This study identified an HNRNPA1 - SLC3A2 regulatory relationship associated with cuproptosis-related phenotypes in RA-FLS and revealed altered m6A enrichment of SLC3A2 mRNA in RA-FLS. These findings provide new insights into the abnormal survival of RA-FLS and identify the HNRNPA1-SLC3A2 regulatory relationship as a candidate pathway for further investigation.