Extracellular Vesicles Released by Tumor Endothelial Cells Spread Immunosuppressive and Transforming Signals Through Various Recipient Cells
Tatiana Lopatina, Enrica Favaro, Ludmila Danilova, Elana J. Fertig, Alexander V. Favorov, Luciane T. Kagohara, Tiziana Martone, Benedetta Bussolati, Renato Romagnoli, Roberto Albera, Giancarlo Pecorari, Maria Felice Brizzi, Giovanni Camussi, Daria A. Gaykalova
Abstract
Head and neck squamous cell carcinoma (HNSCC) has a high recurrence and metastatic rate with an unknown mechanism of cancer spread. Tumor inflammation is the most critical processes of cancer onset, growth, and metastasis. We hypothesize that the release of extracellular vesicles (EVs) by tumor endothelial cells (TEC) induce reprogramming of immune cells as well as stromal cells to create an immunosuppressive microenvironment that favor tumor spread. We call this mechanism as non-metastatic contagious carcinogenesis. EVs were collected from primary HNSCC-derived endothelial cells (TEC-EVs) and were used for stimulation of peripheral blood mononuclear cells (PBMC) and primary adipose mesenchymal stem cells (ASCs). Regulation of ASC gene expression was investigated by RNA sequencing and protein array. PBMC, stimulated with TEC-EVs, were analyzed by enzyme-linked immunosorbent assay and fluorescence-activated cell sorting. We validated in vitro the effects of TEC-EVs on ASCs or PBMC by measuring invasion, adhesion, and proliferation. We found and confirmed that TEC-EVs were able to change ASC inflammatory gene expression signature within 24-48 hours. TEC-EVs were also able to enhance the secretion of TGFβ1 and IL-10 by PBMC and to increase T regulatory cell (Treg) expansion. TEC-EVs carry specific proteins and RNAs that are responsible for Treg differentiation and immune suppression. ASCs and PBMC, treated with TEC-EVs, enhanced proliferation, adhesion of tumor cells, and their invasion. These data indicate that TEC-EVs exhibit a mechanism of non-metastatic contagious carcinogenesis that regulates tumor microenvironment and reprograms immune cells to sustain tumor growth and progression.