Brain derived neutrophic factor (BDNF) coordinates lympho-vascular metastasis through a fibroblast-governed paracrine axis in the tumor microenvironment.

It has long been known that the tumor microenvironment contributes to the proliferation and survival of neoplasms through the constant interaction with the stromal and immune compartments. In this investigation, we explored the role of cancer-associated fibroblasts (CAFs) in the regulation of the tumor microenvironment in head and neck squamous cell carcinoma (HNSCC) though a complex intercellular BDNF-TrkB signaling system. Our studies show that conditioned media derived from patient-derived CAFs promoted HNSCC cell proliferation, in vitro cell migration, cell invasion and chemotherapy resistance, compared to normal fibroblasts. Furthermore, examination of the in vivo impact of CAF pathophysiology in the tumor microenvironment in animal xenograft models revealed that HNSCC cell lines in combination with CAFs promoted tumor growth and increased incidence of lymphovascular metastasis as compared to injection of tumor cells or CAF cells alone. Using pharmacological and genetic alterations, we mechanistically demonstrate the critical importance of BDNF-TrkB signaling in the tumor microenvironment. These investigations further support the rationale for BDNF/TRKB targeted therapy against in the treatment of HNSCC.