Thrombospondin-1 is a multifaceted player in tumor progression

// Tingting Huang 1 , Li Sun 1 , Xianglin Yuan 1 and Hong Qiu 1 1 Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, PR China Correspondence to: Hong Qiu, email: tjqiuhong@163.com Keywords: thrombospondin-1, tumor progression, tumor angiogenesis, cancer cell behavior, tumor immunity Received: March 16, 2017 Accepted: June 28, 2017 Published: July 11, 2017 ABSTRACT Thrombospondins are a family of extracellular matrix (ECM) proteins. Thrombospondin-1 (TSP1) was the first member to be identified and is a main player in tumor microenvironment. The diverse functions of TSP1 depend on the interactions between its structural domains and multiple cell surface molecules. TSP1 acts as an angiogenesis inhibitor by stimulating endothelial cell apoptosis, inhibiting endothelial cell migration and proliferation, and regulating vascular endothelial growth factor bioavailability and activity. In addition to angiogenesis modulation, TSP1 also affects tumor cell adhesion, invasion, migration, proliferation, apoptosis and tumor immunity. This review discusses the multifaceted and sometimes opposite effects of TSP1 on tumor progression depending on the molecular and cellular composition of the microenvironment. Clinical implications of TSP1-related compounds are also discussed.