Inhibitors of Apoptosis Proteins (IAPs): Clinical Significance in Cancer Treatment Research

Apoptosis is a process, which involves a sequence of cellular changes, which ultimately lead to cell death. This programmed cell death is a normal phenomenon required for growth of an organism. Inhibition of apoptosis can result in a number of cancers, inflammatory and autoimmune diseases and viral infections. Inhibitors of apoptosis proteins (IAPs) are a family of structurally and functionally related proteins, which play a crucial role in apoptosis (programmed cell death), proliferation and angiogenesis. Till date 8 IAPs have been identified (Survivin, XIAP, Livin, cellular IAP 1 and 2, ILP-2, NAIP and BRUCE/Apollon). The current review discusses individual protein in details with respect to its structural features, functions and clinical significance. These proteins; especially survivin, XIAP and Livin have been found to express in wide range of malignancies and hence taken as a target of interest by various research groups. The review also highlights the various Phase1 and 2 studies of new therapeutic agents that are being developed either as a monotherapy or in combination with existent drugs, which target these IAPs.