Cancer and cell death

Programmed cell death is an ordered and orchestrated cellular process that occurs in physiological and pathological conditions. Regulated programmed cell death is one of the mechanisms by which multicellular organisms limit the growth and replication of cells. Cell death is essential to control cell growth and tissue homeostasis; it occurs in normal tissues to allow the removal of damaged cells or to maintain a constant number of cells in regenerating tissues and plays an important part in embryogenesis. In an average human adult 50–70 billion cells undergo programmed cell death every day. The abundance of literature suggests that defects in programmed cell death play a crucial role in carcinogenesis. The genetic alterations in the cancer cell not only lead to increased cellular proliferation, as discussed in other chapters of this book, but also lead to loss of programmed cell death, thus increasing tumour growth. Despite being part of the problem, cell death plays an important role in the treatment of cancer as it is an important target of many treatment strategies. Unquestionably, apoptosis is the best-characterized and the most evolutionary conserved form of programmed cell death. Recently, many studies have demonstrated the existence of several other forms of programmed cell death including autophagy, necroptosis, and pyroptosis. In this chapter we discuss several regulated forms of cell death; we outline what we know about their mechanisms and how we can exploit this knowledge to reactivate programmed cell death in tumour cells for the treatment of cancer.