Platelets as messengers of early-stage cancer

Abstract

Platelets have an important role in tumor angiogenesis, growth, and metastasis. The reciprocal interaction between cancer and platelets results in changes of several platelet characteristics. It is becoming clear that analysis of these platelet features could offer a new strategy in the search for biomarkers of cancer. Here, we review the human studies in which platelet characteristics (e.g., count, volume, protein, and mRNA content) are investigated in early-stage cancer. The main focus of this paper is to evaluate which platelet features are suitable for the development of a blood test that could detect cancer in its early stages.

Keywords: Biomarker; Cancer; Early-stage; Platelets.

Fig. 1

Platelets promote tumor angiogenesis cancer growth and metastasis. (1) The prothrombotic tumor microenvironment induces platelet adhesion, activation, and secretion in the (angiogenic) blood vessels within the tumor. (2) Platelet secretome and microparticles induce tumor angiogenesis, vessel stabilization, cancer cell proliferation, and resistance to apoptosis. At the same time, platelets sequester proteins and mRNA from the tumor (and become so-called tumor-educated platelets). (3) Tumor cell-platelet aggregate formation shields circulating tumor cells from the immune system. (4) Platelets support metastatic niche formation by inducing the expression of adhesion molecules and recruitment of stromal cells at potential metastatic sites. (5) Platelet secretome increases tumor cell invasiveness by inducing epithelial-mesenchymal transition (EMT) and inhibiting local immune response

Fig. 2

Heat map and supervised cluster analysis of protein expression data from platelets of early-stage lung or head of pancreas cancer (HoP cancer) patients compared to healthy sex- and age-matched controls. Cancer type-specific supervised cluster analysis clearly separates the platelet proteome of patients with early-stage lung cancer (a) or head of pancreas cancer (b) from healthy controls. Reprinted from [10] with permission