Systemic immune profiling analysis identifying M2-TAM related genes predicted colon cancer prognosis and chemotherapy responses

Colon cancer (COAD) poses great challenges to clinical treatment due to its heterogeneity and complex immune microenvironment. M2-like macrophages significantly influence COAD's onset, progression, and treatment. Yet, existing M2-like macrophage markers are limited in prognostic efficacy, prompting the exploration of new M2 signatures. Extensive data analysis aimed to unveil prognosis-associated M2-derived signatures. Bulk transcriptome, single-cell RNA sequencing, and clinical data from The Cancer Genome Atlas and Gene Expression Omnibus databases for patients with COAD were amassed. Cell-Type Identification by Estimating Relative Subsets of RNA Transcripts identified immune cell infiltration, and the Kaplan-Meier test identified crucial immune populations associated with prognosis. Genetic signatures linked to M2 tumor-associated macrophage were crafted utilizing weighted gene coexpression network analysis, least absolute shrinkage and selection operator, and Cox regression. The M2 tumor-associated macrophage gene signature was validated in GSE17536. The expression profile of the M2 gene signature was investigated in single-cell RNA sequencing dataset GSE166555. Systemic immune profile identified that M2-like macrophage has the most significant prognostic significance in The Cancer Genome Atlas-COAD. The core genes related to M2 macrophage infiltration were extracted by weighted gene coexpression network analysis. Least absolute shrinkage and selection operator-stepwise COX regression-derived M2-derived signatures (snail family zinc finger 1, gastrin-releasing peptide, gamma-aminobutyric acid type A receptor delta subunit, cluster of differentiation 1B, poly(A)-binding protein cytoplasmic 2, manic fringe, and death-associated protein kinase 1) as a risk model, which was confirmed as independent prognosis factors, validated by external dataset. This M2-based prognostic model reflected M2 macrophage infiltration. Mendelian randomization established cytotoxic T lymphocyte associate protein-4 and cluster of differentiation 274 immune checkpoints' causality with COAD. In conclusion, our study developed novel markers for discriminating M2-like macrophages and predicting the prognosis of patients with COAD, offering fresh perspectives for clinical interventions.