SOX2 drives ICIs resistance by restricting cGAS-STING-STAT1 immune activation through DNA repair maintenance

국문 초록 (Abstract)

면역관문억제제(ICI)는 비소세포폐암(NSCLC) 치료의 핵심 요소로 자리 잡았지만, 임상적 효능은 환자마다 큰 차이를 보인다. 특히 명확한 표적 치료 타겟이 없는 폐편평세포암(LUSC)은 ICI 기반 치료에 의존하고 있으며, 치료 반응을 예측할 수 있는 보다 신뢰성 높은 바이오마커를 필요로 한다. LUSC 환자의 약 60%에서 증폭되는 SOX2는 다능성 관련 전사인자로, 종양에 기여하는 유전자로 알려져 있다. 그러나 종양 면역 미세환경을 형성하고, ICI의 반응성에 영향을 미치는 SOX2의 자세한 역할은 아직 충분히 밝혀지지 않았다.
본 연구원은 LUSC환자의 면역 조절에서 SOX2의 역할을 연구하기 위해, 공공 데이터베이스에서 단일 세포 RNA-seq 데이터와 대량 RNA-seq 데이터를 확보하고 재분석하여 종양-면역 상호작용을 규명하였다. In silico분석 결과 추론된 다양한 분자 및 생화학적 경로를 암세포주와 일차 세포에서 검증하여, 기저 메커니즘을 밝혔다. ICI반응은 ICI 치료 코호트의 임상 및 오믹스 데이터를 사용하여 추가로 분석하였다.
TCGA RNA-seq 데이터와 단일 세포 RNA-seq 데이터를 통합 분석한 결과는 SOX2 과발현이 면역 침윤 및 면역 반응 경로 감소와 관련이 있음을 보여주었다. 특히, SOX2 발현이 높은 LUSC에서는 CD8+ T 세포가 차지하는 비율이 유의미하게 낮았고, 조절 T 세포의 비율은 높았다. 이러한 in silico 연구 결과는 in vitro 모델을 통하여 추가로 검증되었다. SOX2는 DNA 복구 시스템을 유지시키며, 따라서SOX2의 손실은 DNA 손상의 누적을 초래하여 cGAS-STING 축을 활성화시킨다. 이는 하위 JAK-STAT 경로 활성화 및 면역 관련 유전자(IRG) 발현 증가로 이어진다. 또한, SOX2는 IRG의 프로모터 또는 인핸서 결합을 위해 STAT1과 경쟁한다. 결과적으로, SOX2를 과발현하는 암세포는 T 세포의 증식, 기능 및 침윤을 억제하여 면역 억제적인 종양 미세환경을 형성한다. 추가적인 임상 ICI 코호트 분석 결과, LUSC에서 높은 SOX2 발현은 ICI에 대한 반응 저하와 상관관계가 있는 것으로 나타났다.
요약하면, SOX2는 cGAS–STING–STAT 매개 면역 활성화 및 T 세포 반응을 억제하여 LUSC에서 종양 면역 회피를 촉진한다. 본 연구자는 SOX2를 치료 타겟으로 제시하여, LUSC ICI의 효능을 향상시킬 수 있는 방법을 제안한다.

다국어 초록 (Multilingual Abstract)

Background: Immune checkpoint inhibitors (ICIs) have become a central component of therapy for non-small cell lung cancer (NSCLC), yet their clinical efficacy varies widely among patients. Lung squamous cell carcinoma (LUSC), which lacks well-defined actionable targets, relies on ICIs-based treatment, underscoring the need for reliable biomarkers that predict therapeutic response. SOX2, amplified in approximately 60% of LUSC cases, is a pluripotency-associated transcription factor with established oncogenic functions; however, its role in shaping the tumor immune microenvironment and influencing ICIs responsiveness remains poorly understood.

Methods: Single cell RNA-seq data and bulk RNA-seq data were obtained from public databases and reanalyzed to characterize tumor-immune interactions. Findings from the in-silico analysis were validated in immortalized and primary cells using various molecular and biochemical assay to elucidate the underlying mechanisms. Immunotherapy responses were further examined using clinically annotated immunotherapy cohorts with omics data.

Results: Bulk RNA-seq data from TCGA and single-cell RNA-seq data demonstrated that SOX2 overexpression is associated with reduced immune infiltration and immune response pathways. In particular, CD8+ T cells were significantly lower, while regulatory T cells were inversely enriched, in tumors with high SOX2 expression. These in silico findings were further validated, and mechanistic studies were conducted using in vitro models. SOX2 sustains DNA repair and its loss results in accumulated DNA damage that activates the cGAS–STING axis, leading to downstream JAK–STAT activation and increased immune-related genes (IRGs) expression. Additionally, SOX2 competed with STAT1 for binding to promoters or enhancers of IRGs. Consequently, SOX2-expressing cancer cells inhibit T-cell recruitment, and cytokine secretion, contributing to an immunosuppressive tumor microenvironment. In line with these findings, analysis of clinical immunotherapy cohorts revealed that high SOX2 expression correlates with poor responses to ICIs in LUSC.

Conclusion: In summary, SOX2 suppresses cGAS–STING–STAT–mediated immune activation and T cell responses, thereby promoting tumor immune evasion. Targeting SOX2 may enhance ICIs efficacy and improve tumor immunotherapy responses.

목차 (Table of Contents)

• Chapter 1. SOX2-mediated immune inactivation underlies poor response to immune checkpoint inhibitors in lung squamous cell carcinoma 1
• 1.1. Abstract 2
• 1.2. Introduction 4
• 1.3. Material and Method 7
• 1.4. Result 10
• 1.4.1. SOX2 was a potential negative marker for ICI response in LUSC 10
• 1.4.2. Immune-related signaling pathways were consistently enriched in both SOX2_low patients and ICI responders 10
• 1.4.3. Screening SOX2-mediated mechanism underlying ICI resistance using TCGA LUSC data 11
• 1.4.4. SOX2 was overexpressed in LUSC but was not sufficient to drive tumor progression 13
• 1.4.5. SOX2 ICI predictive value was investigated across different cancer types 14
• 1.5. Discussion 16
• 1.6. List of Figures 19
• Chapter 2. Immune infiltration is negatively regulated through inhibition of cGASSTINGSTAT signaling by SOX2 31
• 2.1. Abstract 32
• 2.2. Introduction 34
• 2.3. Material and Method 37
• 2.4. Result 48
• 2.4.1. High levels of SOX2 was negatively correlated with immune cell infiltration and Immune response related signaling pathways in LUSC 48
• 2.4.2. CD8 effector T cell infiltration and function were enhanced in SOX2_low patients 50
• 2.4.3. IRGs upregulation was mediated by the JAK-STAT pathway in SOX2-KO cell 51
• 2.4.4. JAKSTAT signaling was activated through the DNA damagecGASSTING axis upon SOX2 knockout 53
• 2.4.5. Immune-related genes were repressed by SOX2 through STAT1 inhibition and competitive interference with STAT1 binding 54
• 2.4.6. T cell recruitment and proliferation were promoted with conditioned medium derived from SOX2-knockout cells 57
• 2.4.7. SOX2-midiated immune regulation role was explored in LUAD and HNSC 58
• 2.5. Discussion 60
• 2.6. List of Figures 63
• 3. References 91
• 4. 논문요약 97