Molecular pathways in cancer-related inflammation

Accumulating evidence shows that chronic inflammation is associated to increased risk of cancer. An inflammatory component is present also in the microenvironment of tumours epidemiologically unrelated to inflammation. Extensive investigations over the past decade have uncovered many of the important mechanistic pathways underlying cancer-related inflammation. Pathways linking inflammation and cancer have been identified: an intrinsic one (driven by genetic events that cause neoplasia) and an extrinsic one (driven by inflammatory conditions which predispose to cancer). Smouldering inflammation is a component of the tumour microenvironment and is a recognized hallmark of cancer. Key orchestrators at the intersection of the intrinsic and extrinsic pathways include transcription factors (e.g. Nuclear Factor kappa-B, NF kappa B) that modulate the inflammatory response through soluble mediators (cytokines, chemokines) and cellular components (e.g. tumor-associated macrophages), promoting tumorigenesis. NF kappa B aids in the proliferation and survival of malignant cells, promotes angiogenesis and metastasis, subverts adaptive immunity, and alters responses to hormones and chemotherapeutic agents. Emerging evidence also suggests that persistent inflammation promotes genetic instability. Thus, cancer-related inflammation represents a target for innovative diagnostic and therapeutic strategies.