Directing cancer cells to self-destruct with pro-apoptotic receptor agonists.

Each day, the human body eliminates billions of unwanted cells by apoptotic suicide. Apoptosis provides an important barrier against cancer; however, specific mutations enable some tumour cells to escape apoptotic death and become more malignant. Two signalling pathways initiate apoptosis: one acts through intracellular Bcl-2 proteins, the other through cell-surface pro-apoptotic receptors. New molecular insights have inspired the development of pro-apoptotic receptor agonists (PARAs), including the recombinant human protein apoptosis ligand 2/TNF-related apoptosis-inducing ligand (Apo2L/TRAIL) and agonistic monoclonal antibodies to its signalling receptors. Acting alone, or in concert with other agents, PARAs may overcome key apoptosis blocks and direct cancer cells to self-destruct.