TYROBP overexpression alters macrophage phenotype and enhances pancreatic cancer stemness through STAT3 and PKM2 signaling.

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a complex tumor microenvironment (TME) that influences tumor progression and therapeutic responses. TYRO protein tyrosine kinase binding protein (TYROBP), a transmembrane polypeptide involved in immune cell signaling, has been implicated in PDAC and associated with M2 macrophage polarization.

METHODS

We investigated the correlation between TYROBP expression and M2 macrophage infiltration in PDAC tissues using multiplex immunofluorescence staining. We also engineered TYROBP overexpression in SW1990 and Capan-1 pancreatic cancer cell lines to evaluate its impact on cell migration and macrophage polarization. Furthermore, we conducted co-culture experiments with SW1990 cells and THP-1 cells to explore the role of TYROBP in macrophage-mediated SW1990 cell proliferation and stemness. Nuclear translocation of STAT3 and PKM2 was assessed in TYROBP-overexpressing SW1990 cells, and the regulatory effects of STAT3 and PKM2 on CXCL8 expression were examined. Finally, molecular docking studies were performed to evaluate the binding of baicalein to STAT3, and in vivo studies assessed the inhibitory effects of baicalein on SW1990 cell proliferation.

RESULTS

High TYROBP expression in PDAC tissues correlated with increased M2 macrophage infiltration, as indicated by elevated CD68 and CD206 levels. TYROBP overexpression promotes M2 macrophage polarization and glycolytic reprogramming via STAT3/PKM2, validated in vitro and in vivo. TYROBP overexpression also promoted the nuclear translocation of STAT3 and PKM2, enhancing glycolytic activity in SW1990 cells. STAT3 and PKM2 cooperated to regulate CXCL8 expression via direct binding to the CXCL8 promoter region. Molecular docking demonstrated baicalein's binding to STAT3, and in vivo studies showed that baicalein significantly inhibited SW1990 cell growth and modulated key signaling pathways.

CONCLUSIONS

Our study reveals that high TYROBP expression is associated with increased M2 macrophage infiltration in PDAC, promoting a pro-tumorigenic TME. TYROBP overexpression drives macrophage polarization towards the M2 phenotype, enhances glycolytic activity, and modulates key signaling pathways. Baicalein, targeting STAT3, shows potential as a therapeutic agent for PDAC by inhibiting cell proliferation and modulating the TME. These findings highlight TYROBP as a key regulator in PDAC progression and suggest potential therapeutic strategies targeting TYROBP and its associated pathways.