Notch activation has been detected in pancreatic ductal adenocarcinoma (PDAC). However, its role in PDAC metastasis remains unknown. In this study, we identify a Notch-dependent feedback circuit between pancreatic cancer cells and macrophages, which contributes to PDAC metastasis. In this circuit, miR-124 regulated Notch signaling in cancer cells by directly targeting the Notch ligand Jagged 1. Autoamplified Notch signaling promoted the recruitment and activation of macrophages to a tumor-supporting M2-like phenotype via downstream IL8, CCL2, IL1α, and uPA paracrine signaling. In turn, activated macrophage-derived IL6 activated the oncogenic transcription factor STAT3 that directly repressed miR-124 genes via a conserved STAT3-binding site in their promoters, thereby promoting cancer cell epithelial-mesenchymal transition and invasion. Disrupting this circuit suppressed liver metastasis in mouse models. Thus, our study suggests that manipulation of this Notch-dependent circuit has a therapeutic potential for the treatment of PDAC metastasis. SIGNIFICANCE: This study provided potential therapeutic targets and robust preclinical evidence for PDAC treatment by interrupting feedback signaling between cancer cells and macrophages with targeted inhibitors.
©2020 American Association for Cancer Research.