Serum Mac2-binding protein glycosylated isomer (M2BPGi) as a prognostic biomarker in pancreatic ductal adenocarcinoma: iCAFs-derived M2BPGi drives tumor invasion.

Background: Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy with a poor prognosis. Mac2-binding protein glycosylated isomer (M2BPGi), a known biomarker for liver fibrosis, is also elevated in other fibrotic tissues. However, its role in PDAC remains unexplored. This study investigates the potential of M2BPGi as a prognostic biomarker for PDAC and elucidates its role in cancer progression.

Methods: We analyzed serum M2BPGi levels in 83 PDAC patients and 60 healthy controls, examining the relationship with clinical outcomes. Tissue immunostaining and in vitro experiments were conducted to investigate M2BPGi-secreting cells and its role.

Results: Serum M2BPGi levels were significantly higher in PDAC patients than in controls (0.98 vs. 0.59, p < 0.0001). Notably, elevated serum M2BPGi was associated with worse progression-free survival (144 days vs. 260 days, p = 0.017) and overall survival (OS) (245 days vs. 541 days, p < 0.001) following chemotherapy. Multivariable Cox regression analysis further confirmed that a high serum M2BPGi level is an independent risk factor for OS (HR: 2.44, 95% CI 1.26-4.74, p = 0.008). Immunostaining revealed that M2BPGi is secreted by both cancer cells and cancer-associated fibroblasts (CAFs), with high M2BP expression in CAFs correlating with poor prognosis. Furthermore, M2BPGi-secreting CAFs exhibited characteristics of inflammatory CAFs. M2BPGi directly activated mTOR signaling and epithelial-mesenchymal transition in PDAC cells, enhancing their invasive and migratory capabilities.

Conclusions: Our findings identify M2BPGi as a promising prognostic biomarker for PDAC. Moreover, we demonstrate that inflammatory CAFs promote tumor invasion and contribute to poor outcomes by secreting M2BPGi, revealing a novel mechanism of PDAC progression.