miR-96-5p-mediated Inhibition of CD47 contributes to pancreatic tumor regression via activating both innate and adaptive anti-tumor immunity.

Blocking immune checkpoints has become a viable immunotherapy option for cancer. CD47, an anti-phagocytic molecule, engages with SIRPα on macrophages to transmit a “don’t eat me” signal, facilitating immunoevasion. This research examined the molecular pathways influenced by miR-96-5p in pancreatic ductal adenocarcinoma (PDAC) and evaluates its clinical and biological significance. Utilizing bioinformatics, Western blot, luciferase reporter assays and RNA fluorescence in situ hybridization, results revealed that miR-96-5p directly targeted and inversely regulated CD47 expression, indicating patient survival in PDAC. Further investigation into the effects of miR-96-5p on PDAC was conducted through co-culture phagocytosis, antigen presentation, and T cell activation experiments, and mouse PDAC models. The results demonstrated that specifically re-establishing miR-96-5p expression in PDAC cells significantly repressed PDAC tumorigenesis and reprogramed the immunosuppressive microenvironment by diminishing CD47 protein abundance. This modulation encouraged the shift of tumor-associated macrophages (TAMs) into pro-phagocytic M1-like phenotypes via exosomal transfer of miR-96-5p and boosted T cell activation within both peripheral and tumor immune microenvironments. Mechanistically, experiments based on the ovalbumin (OVA) antigen system revealed that the phagocytic function of miR-96-5p enhanced the presentation of tumor antigens to T cells, resulting in more effective activation of antigen-specific T cells, instead of miR-96-5p directly activating T cells. The findings verify that miR-96-5p serves as an effective tumor suppressor, reducing tumor burden by triggering both innate and adaptive anti-tumor immune responses, offering a promising avenue for PDAC immunotherapy improvement.