The identification of heterogeneous reactive oxygen subtypes in esophageal squamous cell carcinoma to aid patient prognosis and immunotherapy

Introduction: Esophageal cancer is increasingly recognized as a significant global malignancy. The main pathological subtype of this cancer is esophageal squamous cell carcinoma (ESCC), which displays a higher degree of malignancy and a poorer prognosis. Reactive oxygen species (ROS) play a critical role in modulating the immune response to tumors, and understanding the regulation of ROS in ESCC could lead to novel and improved therapeutic strategies for ESCC patients. Methods: A consensus matrix derived from genes involved in the ROS pathway revealed two subtypes of ROS. These subtypes were categorized as ROS-active or ROS-suppressive based on their level of ROS activity. The heterogeneity among the different ROS subtypes was then explored from various perspectives, including gene function, immune response, genomic stability, and immunotherapy. In order to assess the prognosis and the potential benefits of immunotherapy, a ROS activity score (RAS) was developed using the identified ROS subtypes. In vitro experiments were performed to confirm the impact of core RAS genes on the proliferative activity of esophageal cancer cell lines. Results: Two distinctive subtypes of ROS were identified. The first subtype, referred to as ROS-active, exhibited elevated ROS activity, enhanced involvement in cancer-associated immune pathways, and increased infiltration of effector immune cells. The second subtype, named ROS-suppressive, demonstrated weaker ROS activity but displayed more pronounced dysregulation in the cell cycle and a denser extracellular matrix, indicating malignant characteristics. Genomic stability, particularly in terms of copy number variation (CNV) events, differed between the two ROS subtypes. By developing a RAS model, reliable risk assessment for overall survival (OS) in patients with ESCC was achieved, and the model demonstrated strong predictive capabilities in real-world immunotherapy cohorts. Moreover, the core gene LDLRAD1 within the RAS model was found to enhance proliferative activity in esophageal cancer cell lines. Conclusion: Based on the ROS pathway, we successfully identified two distinct subtypes in ESCC: the ROS-active subtype and the ROS-suppressive subtype. These subtypes were utilized to evaluate prognosis and the sensitivity to immunotherapy.