The Role of Platelet Activation in the Development and Metastasis of Solid Tumors

Abstract

The blood coagulation system is actively involved in the development of cancer. It is known that many solid tumors express tissue factor, a “trigger” of the cascade of plasma coagulation reactions, which leads to an increased risk of cancer-associated thrombosis and venous thrombosis in cancer patients. It has also long been known that platelets - small cellular fragments that are the basis of blood clots - play a critical role in metastasis by binding to the tumor cell after it enters the blood vessel, “shielding” it from the immune system and promoting the adhesion and extravasation of the tumor cell into tissues and the formation metastasis. In addition, platelets, being mobile “storehouses” of growth factors, are actively attracted and, in some cases, consumed by the tumor, which contributes to its development and vascularization. Platelet attraction occurs both through activation of the blood coagulation system in the tumor area and through exposure of the adhesive surface by the tumor. Activated in the tumor vicinity, platelets attract and induce neutrophil activation and the formation of neutrophil extracellular traps (NETs), thereby modulating the tumor microenvironment. When activated, platelets are known to secrete a variety of growth factors that promote both tumor development and vascularization. In addition to direct interaction, platelets and tumor cells exchange mRNA, micro-RNA and other regulatory molecules through microvesicles, while platelets are containers for the spread of tumor genetic material (circulating nucleic acids) throughout the body. In this review, we consider the molecular mechanisms of platelet participation in the development and metastasis of solid tumors, and also discuss possible options for pharmacological interruption of this interaction.