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CRISPR Screening Reveals SAA1-Driven Neutrophil Extracellular Traps Promote CD8⁺ T Cell Dysfunction in Renal Cell
Xin Luo1, Xiangpeng Zou1, Yi Wu2
1Sun Yat-sen University Cancer Center Guangzhou China.
Abstract:
Immune checkpoint inhibitors are a frontline treatment for metastatic renal cell carcinoma (RCC), one of the most common malignancies of the urinary system. However, a large proportion of patients exhibit poor responses or develop resistance, which severely limits the therapeutic efficacy and patient survival. In this study, we constructed a custom CRISPR activation library based on the top 500 genes upregulated in anti-PD-1-resistant RCC cells. Functional screening identified serum amyloid A1 (SAA1) as a critical mediator of resistance; SAA1 activation promoted immune evasion, while deficiency sensitized RCC cells to anti-PD-1 treatment. SAA1 promoted anti-PD-1 resistance both in RCC patients and in mouse models. Mechanistically, SAA1 bound to toll-like receptor 2 (TLR2) and activated the NF-κB signaling pathway, thereby inducing the formation of neutrophil extracellular traps (NETs). These NETs not only acted as physical barriers that blocked direct contact between CD8⁺ T cells and tumor cells but also promoted CD8⁺ T cell exhaustion, facilitating tumor immune evasion and resistance to immunotherapy. Both in vitro and in vivo experiments demonstrated that suppression of SAA1 significantly reduced NET formation and enhanced the efficacy of immunotherapy. In conclusion, SAA1 promotes immunotherapy resistance in RCC by driving NET formation via the TLR2/NF-κB axis and inducing CD8⁺ T cell dysfunction. Targeting SAA1 may represent a promising strategy to overcome immune resistance in RCC.
Insights
Serum amyloid A1 (SAA1) drives resistance to immunotherapy in metastatic renal cell carcinoma (RCC) by promoting neutrophil extracellular traps (NETs). Targeting SAA1 may improve treatment efficacy for RCC patients.
Area of Science:
- Oncology
- Immunology
- Genetics
Background:
- Metastatic renal cell carcinoma (RCC) is a common urinary system malignancy.
- Immune checkpoint inhibitors (ICIs) are a primary treatment, but resistance limits efficacy.
- Identifying resistance mechanisms is crucial for improving RCC patient survival.
Purpose of the Study:
- To identify genes mediating resistance to anti-PD-1 therapy in RCC.
- To investigate the role of serum amyloid A1 (SAA1) in immunotherapy resistance.
- To elucidate the mechanism by which SAA1 promotes immune evasion in RCC.
Main Methods:
- Constructed a CRISPR activation library targeting upregulated genes in anti-PD-1-resistant RCC cells.
- Performed functional screening to identify key resistance mediators.
- Utilized in vitro and in vivo models, including patient data and mouse models, to validate findings.
- Investigated the molecular mechanism involving SAA1, toll-like receptor 2 (TLR2), NF-κB signaling, and neutrophil extracellular traps (NETs).
Main Results:
- Serum amyloid A1 (SAA1) was identified as a critical mediator of anti-PD-1 resistance in RCC.
- SAA1 activation promoted immune evasion, while SAA1 deficiency sensitized RCC cells to anti-PD-1 treatment.
- SAA1 activates the TLR2/NF-κB pathway, inducing NET formation that hinders CD8+ T cell function and promotes immune evasion.
- Suppression of SAA1 reduced NET formation and enhanced immunotherapy efficacy in both in vitro and in vivo settings.
Conclusions:
- SAA1 is a key driver of immunotherapy resistance in RCC through NET formation and CD8+ T cell dysfunction.
- The SAA1-TLR2-NF-κB-NET axis represents a novel mechanism of immune evasion in RCC.
- Targeting SAA1 offers a potential therapeutic strategy to overcome immunotherapy resistance in RCC.
