Key functions of exosomal TGF-β

Function of exosomal TGF-βMechanismResulting effectCancer type(s)Reference(s)
Fibroblast differentiation and activationActivates SMAD-dependent signaling upon internalization into fibroblasts.Promotes differentiation of fibroblasts into CAFs, enhances CAF marker expression.Prostate cancer, bladder cancer, gastric cancer, and lung adenocarcinoma.[8991, 103]
ECM remodelingEnhances LOX activity, leading to collagen cross-linking.Stiffens the ECM, creating a favorable environment for metastasis development.General (tumor microenvironment).[87, 103]
Angiogenesis promotionStimulates angiogenesis via myofibroblast phenotype.Enhances tumor growth in vivo.Prostate cancer.[89]
MSC modulationTGF-β interaction with receptors on MSCs.Increases synthesis and release of pro-inflammatory IL-6, supporting metastasis via immunosuppression.Osteosarcoma, chronic myeloid leukemia.[92, 95, 96]
Non-coding RNA-mediated signalingDelivery of circPAGRGL, miR-21-5p, miR-92, miR-142-3p, and miR-506-3p via exosomes.Induces TGF-β expression, enhances cell proliferation and metastasis, promotes EMT, and supports phenotypic switch of neutrophils to pro-tumorigenic N2.Colorectal cancer, gastric cancer, and lung cancer.[93, 94, 100]
Premetastatic niche formationActivation of TGF-β signaling in hepatic Kupffer cells and stellate cells.Remodels liver tissue, making it more favorable for metastasis by stimulating fibronectin and collagen type I production.Pancreatic ductal adenocarcinoma, lung cancer.[98, 100]
EMT inductionActivation of SMAD2/3 signaling.Promotes a more motile and invasive mesenchymal phenotype, enhancing migration and invasion.General (ovarian cancer).[104]
Immune suppressionTransfer of TGF-β1 to tumor-infiltrating natural killer cells.Impairs NK cell functioning via TGF-β/SMAD pathway activation, supports immune evasion of quiescent cells.Renal cell carcinoma.[105]
Macrophage reprogrammingStimulation of macrophage chemotaxis and reprogramming.Promotes proangiogenic phenotype in macrophages, characterized by upregulation of proangiogenic factors.Head and neck squamous cell carcinoma.[80]

CAFs: cancer-associated fibroblasts; ECM: extracellular matrix; EMT: epithelial-mesenchymal transition; LOX: lysyl oxidase; MSC: mesenchymal stem cell; TGF-β: transforming growth factor-β