Inflammation and oncogenesis: a vicious connection

Abstract

Epidemiological and experimental data suggest a close connection between inflammation and tumorigenesis. Solid tumors are typically infiltrated with immune cells and inflammation impacts most, if not all, stages of tumorigenesis. Molecular and cellular pathways, which connect inflammation and cancer, have emerged as attractive targets for prevention and therapy. In this review we discuss general mechanisms and concepts of cancer promoting inflammation.

Figure 1

Inflammation is important at various stages of tumorigenesis. Inflammation may contribute to tumor initiation by inducing DNA damage through intermediates like ROS and via activation of epigenetic mechanisms, which lead to silencing of tumor suppressor genes. During tumor promotion, immune and inflammatory cells produce cytokines and chemokines, which facilitate cancer cell survival, proliferation and promote the angiogenic switch. This results in increased tumor growth. Cytokines and chemokines also induce further recruitment and differentiation of immune cells in the tumor microenvironment. At the tumor progression and metastasis stages, immune cells further contribute by production of cytokines and chemokines to increase cell survival, motility and invasiveness, as well as to promote epithelial mesenchymal transition (EMT).