Virus induced inflammation and cancer development

• Tumourigenic viruses HBV, HCV, EBV, KSHV, HTLV and HPV all have confirmed roles in cancer initiation.
• Inflammation as a result of chronic infection is mediated directly by viral proteins and indirectly as a result of viral replication.
• HBV/HCV mediated inflammation plays a particularly prominent role in cancer initiation and progression, due to significant cell death and regeneration.
• Inflammatory activation mediated directly by viral proteins is often a result of pathway overlap with growth/apoptosis signalling pathways (particularly NF-κB).

Chronic inflammation as a result of viral infection significantly increases the likelihood of cancer development. A handful of diverse viruses have confirmed roles in cancer development and progression, but the list of suspected oncogenic viruses is continually growing. Viruses induce cancer directly and indirectly, by activating inflammatory signalling pathways and cytokines, stimulating growth of infected cells and inhibiting apoptosis. Although oncogenic viruses induce inflammation by various mechanisms, it is generally mediated by the MAPK, NFκB and STAT3 signalling pathways. This review will explore the unique mechanisms by which different oncogenic viruses induce inflammation to promote cancer initiation and progression.