Abstract:Objective To explore the relationship between actin-related protein 2/3 complex subunit 1B（ARPC1B）gene and pan-cancer prognosis，tumor immune microenvironment ，and its functional phenotype in clear cell renal cell carcinoma（ccRCC）. Methods The expression of ARPC1B in pan-cancer and its impact on the tumor immune microenvironment were explored using the Cancer Genome Atlas（TCGA）. Subcellular localization of ARPC1B was analyzed using the Human Protein Atlas（HPA）. The potential association between ARPC1B and pan-cancer survival prognosis was assessed using Kaplan-Meier survival analysis and univariate Cox regression analysis. In ccRCC，the role of ARPC1B in promoting tumor progression was further investigated using the GEO database，clinical tissue samples， and cell experiments.Results ARPC1B was predominantly located in the cytoplasm and was significantly overexpressed in most tumor tissues compared to normal tissues，closely associated with poor clinical prognosis. ARPC1B was positively correlated with tumor mutation burden（TMB） and microsatellite instability（MSI）. These characteristics were particularly pronounced in ccRCC. KEGG/GO enrichment analysis further confirmed that ARPC1B may be involved in regulating multiple signaling pathways of the immune microenvironment. Clinical samples and cell experiments confirmed that ARPC1B was highly expressed in ccRCC，and it significantly promoted cancer cell growth，invasion，and migration（P<0.05）. Conclusion ARPC1B can induce a malignant phenotype in ccRCC，and its high expression is associated with poor prognosis in multiple cancers. It may also play a role in regulating the immune microenvironment.The potential value of ARPC1B in prediction of tumor prognosis and immunotherapy efficacy warrants further investigation.