The role and function validation of P2RX4 as a novel cancer biomarker in pan-cancer analysis

Purinergic Receptor P2X4 (P2RX4) is implicated in the carcinogenesis of several cancers, but no extensive study on its role in different forms of cancer. Expression level, gene mutation, immune infiltration, pathway enrichment, and prognostic value analysis of P2RX4 were performed based on multiple publicly available databases such as TCGA, GTEx, GEO, TIMER2, cBioportal, and Metascape databases. Western blot and RT-qPCR were used to identify P2RX4 expression in liver hepatocellular carcinoma (LIHC) and paracancer samples. P2RX4 was knocked in glioblastoma cell line (U251) and prostate cancer cell line (PC3), and its effects on cell viability, apoptosis, migration and invasion were investigated through cell counting kit-8 assay, flow cytometry, wound healing and trasnwell assays, respectively. P2RX4 expression was elevated in most cancers, which predicted poor overall survival and disease-free survival. Mutations in P2RX4 were predominantly found in Lymphoid Neoplasm Diffuse Large B-cell Lymphoma (> 4%). P2RX4 expression showed a positive correlation with the infiltration levels of cancer-associated fibroblasts and CD8 + cells in multiple tumor types. Functional enrichment analysis indicated that P2RX4 is closely related to autophagy, protein modification or intracellular trafficking. P2RX4 was highly expressed in LIHC compared to paracancerous tissues. Knockdown of P2RX4 suppressed cell viability, migration, invasion, and promoted cell apoptosis of U251 and PC3 cells. Overexpression of P2RX4 occurred in multi cancers, and was connected to an unfavorable prognosis. This pan-cancer analysis highlighted the predictive value and tumorigenic role of P2RX4.