Prognostic stratification of colorectal cancer by immune profiling reveals SPP1 as a key indicator for tumor immune status

Abstract Objectives The urgency of screening patients for the potential benefit of immunotherapy has prompted explorations of predictive biomarkers or stratification for colorectal cancer (CRC). This study aims to explore the molecular subtypes associated with immune-related genes (IRGs) in CRC and to further elucidate the underlying molecular mechanisms. Methods IRGs were downloaded for non-negative matrix factorization (NMF) clustering. Kaplan-Meier survival analyses were used to assess survival differences. Gene set variation analysis was conducted for the exploration of potential biological mechanisms and pathways. The hub differentially expressed genes (DEGs) were selected via machine learning. Immunohistochemistry was performed to determine the expression of the hub gene and the infiltration of immune components. Results A preliminary classification of CRC subclasses was conducted through the NMF consensus clustering. Cluster 1 was found to exhibit worse overall survival and progression-free survival than Cluster 2. The two clusters demonstrated different enriched pathways, tumor immune scores, and differential gene expression. The intersection of screening characteristic genes pertained to two genes, SPP1 and GUCA2A. Immunohistochemistry indicated that SPP1 was overexpressed in CRC tissues. Patients with high SPP1 expression demonstrated a poorer prognosis, whether at the transcriptional or protein level. Immunohistochemistry revealed that high SPP1 expression was associated with more neutrophil and less CD8 + T cell infiltration. Conclusions NMF algorithm categorized CRC patients into two immunophenotypically distinct clusters with prognostic implications and a unique profile. SPP1 emerged as a crucial indicator for assessing tumor immune status, providing novel insights to enhance prognostic assessments and therapeutic strategies tailored to individual CRC patients.