Role of X-linked Inhibitor of Apoptosis Protein as Cancer Biomarker

Abstract

X-linked Inhibitor of Apoptosis Protein (XIAP), is one of the most important apoptotic inhibitors that plays a vital role in regulating various aspects of cell functions including cell cycle progression, arrest, and apoptosis. It is one of the most potent and widely studied members of the Inhibitors of Apoptosis Protein (IAP) family which promotes cell survival by inhibiting both extrinsic and intrinsic pathway of apoptosis depending on its intracellular concentration. It blocks major molecules (caspases-3, 7 and 9) which leads to the apoptosome formation responsible for cell death by neutralising caspases-3, 7 and caspase-9, through BIR3 and BIR2 domain respectively. As XIAP has a dominant contribution in the suppression of apoptosis in cancer cells and promotes cell growth, it plays an important role in development of various types of cancers. Overexpression of this protein is directly correlated with the prognosis of different malignancies. The property of XIAP as an apoptosis inhibitor with overexpression in different cancers makes it a useful therapeutic target for cancer therapy especially in resistant tumours and is a focus of molecular and clinical research both in vitro and in vivo. This review summarizes current knowledge on differential roles of XIAP as a cancer biomarker in common malignancies, its role as a predictive and prognostic tool and therapeutic target for cancer therapy.

Keywords

• caspases
• cell death
• cellular homeostasis