Inflammation and tissue homeostasis: the NF-κB system in physiology and malignant progression

Disruption of tissue function activates cellular stress which triggers a number of mechanisms that protect the tissue from further damage. These mechanisms involve a number of homeostatic modules, which are regulated at the level of gene expression by the transactivator NF-kappa B. This transcription factor shifts between activation and repression of discrete, cell-dependent gene expression clusters. Some of its target genes provide feedback to NF-kappa B itself, thereby strengthening the inflammatory response of the tissue and later terminating inflammation to facilitate restoration of tissue homeostasis. Disruption of key feedback modules for NF-kappa B in certain cell types facilitates the survival of clones with genomic aberrations, and protects them from being recognized and eliminated by the immune system, to enable thereby carcinogenesis.