Macrophages and the hypoxic tumour microenvironment.

One characteristic of solid tumour tissue is the presence of large numbers of tumour-associated macrophages. These migrate down gradients of chemo-attractive agents to accumulate within hypoxic and / or necrotic areas where they are generally related to poor clinical prognosis. In this review we will discuss the molecular mechanisms that underlie recruitment of macrophages into tumours and their pro-tumourigenic activities with respect to stimulation of angiogenesis, lymphangiogenesis, tumour cell migration, metastasis and immuno-suppression. The potential of macrophage-related anticancer therapies will be discussed in the light of this phenotype.