Gastric Cancer-Derived Extracellular Vesicles (EVs) Promote Angiogenesis via Angiopoietin-2

SIMPLE SUMMARY: Angiogenesis is the formation of new blood vessels, which is essential for gastric cancer growth and metastasis. Angiopoietin-2 is a key driver of tumor angiogenesis and has recently emerged as a promising target for antiangiogenic therapy. Extracellular vesicles play an important role in tumor progression including angiogenesis. We explored the crosstalk between gastric cancer and endothelial cells mediated by vesicles, with a specific focus on angiopoietin-2. We show that primary gastric cancer and omental metastasis tissues express angiopoietin-2. We isolated gastric cancer vesicles and demonstrated that they induce the proliferation, migration, invasion, and tube formation of endothelial cells. Characterization of the angiogenic profile of these vesicles revealed high levels of proangiogenic proteins including angiopoietin-2. Using angiopoietin-2 knockdown, we demonstrate that angiopoietin-2 mediates the proangiogenic effects of the gastric cancer vesicles. Our findings suggest a new mechanism via which gastric cancer cells induce angiogenesis. Such a mechanism may be used as a target for cancer therapy. ABSTRACT: Angiogenesis is an important control point of gastric cancer (GC) progression and metastasis. Angiopoietin-2 (ANG2) is a key driver of tumor angiogenesis and metastasis, and it has been identified in primary GC tissues. Extracellular vesicles (EVs) play an important role in mediating intercellular communication through the transfer of proteins between cells. However, the expression of ANG2 in GC-EVs has never been reported. Here, we characterized the EV-mediated crosstalk between GC and endothelial cells (ECs), with particular focus on the role of ANG2. We first demonstrate that ANG2 is expressed in GC primary and metastatic tissues. We then isolated EVs from two different GC cell lines and showed that these EVs enhance EC proliferation, migration, invasion, and tube formation in vitro and in vivo. Using an angiogenesis protein array, we showed that GC-EVs contain high levels of proangiogenic proteins, including ANG2. Lastly, using Lenti viral ANG2-shRNA, we demonstrated that the proangiogenic effects of the GC-EVs were mediated by ANG2 through the activation of the PI3K/Akt signal transduction pathway. Our data suggest a new mechanism via which GC cells induce angiogenesis. This knowledge may be utilized to develop new therapies in gastric cancer.