The Opposing Roles of Cellular Inhibitor of Apoptosis Proteins in Cancer

Cellular inhibitors of apoptosis proteins 1 and 2 (cIAP1/2) are members of the inhibitor of apoptosis protein (IAP) family that has been implicated in the pathology of human cancers due to their overexpression and function as blockers of cell death in various cancers. As a result, small molecule IAP antagonists have been developed and are currently under clinical evaluation for potential therapeutic use. In contrast, recent evidence has indicated a tumour-suppressing role for the cIAPs. Mutations in or loss of cIAPs have been identified as molecular lesions that contribute to constitutive activation of NF- κ B in hematopoietic malignancies. These studies reveal a context-dependent role for the cIAPs wherein both their overexpression and loss may contribute to tumourigenesis.