Death receptors as targets for anti-cancer therapy

Abstract

Human tumour cells are characterized by their ability to avoid the normal regulatory mechanisms of cell growth, division and death. The classical chemotherapy aims to kill tumour cells by causing DNA damage-induced apoptosis. However, as many tumour cells possess mutations in intracellular apoptosis-sensing molecules like p53, they are not capable of inducing apoptosis on their own and are therefore resistant to chemotherapy. With the discovery of the death receptors the opportunity arose to directly trigger apoptosis from the outside of tumour cells, thereby circumventing chemotherapeutic resistance. Death receptors belong to the tumour necrosis factor receptor superfamily, with tumour necrosis factor (TNF) receptor-1, CD95 and TNF-related apoptosis-inducing ligand-R1 and -R2 being the most prominent members. This review covers the current knowledge about these four death receptors, summarizes pre-clinical approaches engaging these death receptors in anti-cancer therapy and also gives an overview about their application in clinical trials conducted to date.

Fig. 1

The six currently known death receptors and their respective ligands. All receptors contain several cytokine-rich domains (green) that are responsible for binding to the respective ligands. Following the transmembrane domain, the cytoplasmic region of each receptor pocesses a death domain (red) that is responsible for apoptosis induction.

Fig. 2

The extrinsic and intrinsic apoptotic pathway.