Exosomal P4HA3: a promising biomarker for diagnosis and prognosis in gastric cancer.

Gastric cancer (GC) poses a significant global health burden due to its high mortality rate, which is partly attributable to the lack of sensitive and non-invasive diagnostic tools for early detection. Exosomes, nano-sized extracellular vesicles, have emerged as key mediators of intercellular communication and promising sources of biomarkers in various cancers, including GC. To identify novel exosome-related biomarkers, we focused on prolyl 4-hydroxylase subunit alpha 3 (P4HA3) mRNA levels in plasma-derived exosomes and investigated its role in GC tissues. We integrated bioinformatics analyses and experimental validation to investigate the clinical significance and functional role of P4HA3 in exosomes and GC tissues. Its expression was assessed using RNA sequencing (RNA-seq) data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) datasets. Diagnostic and prognostic values were evaluated via receiver operating characteristic (ROC) and Kaplan-Meier survival curves. Functional enrichment, immune infiltration, and drug sensitivity analyses were conducted in silico. Furthermore, the oncogenic functions of P4HA3 in GC tissues were rigorously examined using in vitro and in vivo models. P4HA3 was significantly upregulated both in GC tissues and plasma-derived exosomes from GC patients. Elevated tissue P4HA3 expression was strongly associated with advanced tumor stage and served as a predictor of poor overall survival (OS). Bioinformatics analyses implicated P4HA3 in pathways related to extracellular matrix (ECM) organization and epithelial-mesenchymal transformation (EMT). These findings were substantiated by functional assays, which demonstrated that P4HA3 knockdown in GC cells significantly suppressed cell proliferation, migration, and induced apoptosis, as well as markedly inhibiting tumor growth in a xenograft mouse model. Further investigation indicated that the oncogenic role of P4HA3 was associated with COL1A1 upregulation and PI3K-AKT signaling pathway activation. Collectively, our findings indicate that exosomal P4HA3 may serve as a novel, non-invasive biomarker for GC diagnosis and prognosis. Given that P4HA3 plays a central role in driving tumor progression, which is associated with the COL1A1 upregulation and PI3K-AKT activation, it represents a promising therapeutic target worthy of further investigation.