Loss of NCCRP1 overcomes immune evasion in lung adenocarcinoma.

BACKGROUND: The low response rate to immunotherapy in patients with lung adenocarcinoma is primarily due to tumor immune evasion. The tumor immunosuppressive microenvironment orchestrates this evasion, yet the underlying mechanisms remain elusive. Here we identify non-specific cytotoxic cell receptor protein 1 (NCCRP1) as a critical and previously uncharacterized regulator of this process. METHODS: We first analyzed publicly accessible patient-derived single-cell RNA sequencing and RNA sequencing data to investigate the expression of NCCRP1 in lung adenocarcinoma and its impact on the tumor immune microenvironment. Subsequently, the Nccrp1 gene was knocked out in mouse lung adenocarcinoma cells using CRISPR-Cas9. The effect of NCCRP1 deletion on tumor growth was then evaluated using subcutaneous transplantation models in both NSG and C57BL/6 mice. Single-cell RNA sequencing, flow cytometry and multiple targeted in vivo interventions were employed to assess the influence of NCCRP1 on the tumor immune microenvironment. To explore the underlying mechanisms by which NCCRP1 regulates the tumor immune microenvironment, we conducted co-immunoprecipitation, RNA pull-down, ubiquitination assay, mass spectrometry, isobaric tags for relative and absolute quantitation proteomics, dual-luciferase reporter gene assay, and ELISA. RESULTS: Loss of NCCRP1 inhibits lung tumor growth and prolongs survival in immunocompetent C57BL/6 mouse models. NCCRP1 deficiency upregulates CX3CL1 to recruit CX3CR1+ antitumoral macrophages. These macrophages subsequently secrete CXCL9 and CXCL10, enhancing the infiltration of CD8+ T cells and NK cells into the tumor microenvironment. Mechanistically, NCCRP1 and STAU1 competitively bind to NEDD4. NCCRP1 deficiency enhances the STAU1-NEDD4 interaction, promoting ubiquitination and proteasomal degradation of STAU1, thereby increasing CX3CL1 messenger RNA stability. Remarkably, ablating NCCRP1 synergized with anti-programmed cell death protein 1 or interferon-γ therapy, leading to complete tumor eradication. CONCLUSION: Our findings highlight NCCRP1 targeting as a promising therapeutic strategy to reprogram the immunosuppressive microenvironment and overcome the "cold tumor" phenotype in lung adenocarcinoma.