모건우 (한국과학기술연합대학원)

이주연 (한국기초과학지원연구원)

모건우 (한국과학기술연합대학원)

송주환 (고려대학교)

조건 (한국기초과학지원연구원)

우창곡 (충북대학교)

이주연 (한국기초과학지원연구원)

Background: PDAC shows immune evasion and poor prognosis, often with dense fibrosis; a subset exhibits abundant tumor-infiltrating neutrophils (TINs) acting as MDSCs. This study defines the proteomic/phosphoproteomic landscape of neutrophil-rich PDAC.

Methods: FFPE specimens were classified as neutrophil-rich (N, n=6), fibrotic (F, n=6), and normal pancreas (P, n=6). Proteins were TMT18-labeled and analyzed by LC-MS/MS after fractionation; phosphopeptides were enriched via Fe3+-IMAC. Differential expression was assessed by ANOVA/t-tests with PCA and pathway enrichment.

Results: We quantified 5,771 proteins and 447 phosphopeptides (336 phosphoproteins); 3,679 proteins and 96 phosphopeptides differed significantly (FDR<0.05). PCA separated normal from tumor tissue. N vs P and F vs P yielded 2,864 and 3,267 DEPs, with minimal N-F differences. Neutrophil-rich tumors showed enrichment in neutrophil degranulation, NET formation, and CXCR4 signaling, with elevated MPO, CD66b, and ELANE. Phosphoproteomics identified 88 regulated phosphopeptides linked to cytoskeletal remodeling via Rho GTPase signaling and immune-cell migration.

Conclusions: Neutrophil-infiltrated PDAC shows a distinct immunosuppressive microenvironment marked by elevated MPO, CD66b, and NET signaling. Despite sharing an oncogenic background with fibrotic PDAC, phosphoproteomic changes reveal subtype-specific mechanisms, informing MDSC-associated PDAC biology and neutrophil-targeted therapy.