Lysosomes as “Suicide Bags” in Cell Death: Myth or Reality?

50 years ago, Christian de Duve introduced the term "suicide bags" to describe lysosomes (1), the organelles containing numerous hydrolases, which were, until the discovery of the ubiquitin-proteasome system, thought to be responsible for the major part of the intracellular turnover of proteins and other macromolecules. It is well established now that the endosomal/ lysosomal system has numerous other functions, including survival functions. Recently, lysosomes and lysosomal proteases were found to participate in cell death pathways, which, at least during apoptosis, are suicidal for cells. It seems timely therefore to discuss whether or not lysosomes in fact play suicidal roles in cellular processes.