TGFβ+ small extracellular vesicles from head and neck squamous cell carcinoma cells reprogram macrophages towards a pro-angiogenic phenotype

Transforming growth factor beta (TGF beta) is a major component of tumor-derived small extracellular vesicles (TEX) in cancer patients. Mechanisms utilized by TGF beta(+) TEX to promote tumor growth and pro-tumor activities in the tumor microenvironment (TME) are largely unknown. TEX produced by head and neck squamous cell carcinoma (HNSCC) cell lines carried TGF beta and angiogenesis-promoting proteins. TGF beta(+) TEX stimulated macrophage chemotaxis without a notable M1/M2 phenotype shift and reprogrammed primary human macrophages to a pro-angiogenic phenotype characterized by the upregulation of pro-angiogenic factors and functions. In a murine basement membrane extract plug model, TGF beta(+) TEX promoted macrophage infiltration and vascularization (p < 0.001), which was blocked by using the TGF beta ligand trap mRER (p < 0.001). TGF beta(+) TEX injected into mice undergoing the 4-nitroquinoline-1-oxide (4-NQO)-driven oral carcinogenesis promoted tumor angiogenesis (p < 0.05), infiltration of M2-like macrophages in the TME (p < 0.05) and ultimately tumor progression (p < 0.05). Inhibition of TGF beta signaling in TEX with mRER ameliorated these pro-tumor activities. Silencing of TGF beta emerges as a critical step in suppressing pro-angiogenic functions of TEX in HNSCC.

Automated summary

Transforming growth factor beta (TGF beta) is a major component of tumor-derived small extracellular vesicles (TEX) that can promote tumor growth and pro-tumor activities in the tumor microenvironment (TME). TGF beta(+) TEX can stimulate macrophage chemotaxis and reprogram primary human macrophages to promote angiogenesis and tumor progression. Inhibition of TGF beta signaling in TEX can suppress these pro-tumor activities in head and neck squamous cell carcinoma (HNSCC).