Figure 2

The potential role(s) of tumor associated eosinophils. Tumor development has been characterized as proceeding through several stages (initiation, promotion, progression). The initiation stage is a period of mutagenesis where genetic and/or epigenetic alternations in stem cells or progenitor cells are established. The promotion stage invokes cellular growth (mitogenesis) that is induced by growth factors and altered apoptotic cell signal pathways. This increased cell division creates a microenvironment of metabolic stress, hypoxia and necrotic cell death that has also been associated with thrombosis. The progression stage involves additional genetic and epigenetic events that confer phenotypic changes necessary for tumor cell autonomous growth, invasiveness, and migration. Eosinophils are able to produce growth factors, cytokines, chemokines, blood coagulants, and cytotoxic mediators that may affect each stage of tumor development.