CXCR4 up-regulation mediated by USP1 deubiquitination promotes the tumorigenesis and immune escape in esophageal squamous-cell carcinoma.

Abstract

CXC chemokine receptor 4 (CXCR4) and ubiquitin specific protease 1 (USP1) have been reported to involve in the tumorigenesis of esophageal squamous-cell carcinoma (ESCC). Here, we investigated whether USP1 induced CXCR4 deubiquitination in regulating ESCC progression. MTT assay, 5-ethynyl-2'-deoxyuridine assay, flow cytometry, transwell assay and ELISA analysis were used to detect cell oncogenic phenotypes, macrophage phenotypes, inflammatory cytokines production, the cytotoxicity of cytokine-induced killer (CIK) cells and CD8 + T cell apoptosis. Protein interaction was determined by immunoprecipitation assay. Cellular ubiquitination detected the ubiquitination effect on CXCR4. A mouse xenograft model was established for in vivo experiments. CXCR4 was highly expressed in ESCC tissues and cells. Functionally, CXCR4 silencing suppressed ESCC cell proliferation, invasion, and induced cell apoptosis. Moreover, CXCR4 deficiency suppressed cancer cell immune escape by suppressing macrophage M2 polarization, elevating inflammatory cytokines produced by PBMCs, enhancing the cytotoxicity of CIK cells, and suppressing CD8 + T cell apoptosis. A high USP1 expression was observed in ESCC, USP1 interacted with CXCR4 and enhanced its protein stability through deubiquitination. USP1 silencing suppressed ESCC cell proliferation, invasion, and immune escape, which were reversed by CXCR4 overexpression. In vivo assay showed that USP1 deficiency impeded tumor growth by regulating CXCR4. Besides, fused in sarcoma (FUS) was confirmed to bind to USP1 and stabilized its mRNA expression, and could regulate CXCR4 via USP1. In conclusion, USP1 stabilized CXCR4 by removing ubiquitination on CXCR4, thereby promoting ESCC cell proliferation, invasion, and immune escape in vitro, and tumor growth in vivo.