CD95, known also as Fas and APO-1, is a classical death receptor that regulates tissue homeostasis through apoptosis. Here it is shown that cancer cells, regardless of their sensitivity to CD95-induced apoptosis, depend for optimal growth on CD95. Without CD95 the incidence of ovarian cancer and liver cancer in mice models is reduced, as is their tumour size. CD95 therefore appears to be a double-edged sword: in order to kill tumour cells it may be necessary to reduce, rather than enhance, CD95 activity. CD95 is a classical death receptor protein that regulates tissue homeostasis by inducing cell death. Here it is shown, however, that cancer cells depend on CD95 for optimal growth. Without CD95, the incidence of ovarian cancer and liver cancer in mice is reduced, as is the size of any tumours. So CD95 is a double-edged sword, and it may be necessary to reduce, rather than enhance, its activity in order to kill tumour cells. CD95 (also called Fas and APO-1) is a prototypical death receptor that regulates tissue homeostasis mainly in the immune system through the induction of apoptosis1,2,3. During cancer progression CD95 is frequently downregulated or cells are rendered apoptosis resistant4,5, raising the possibility that loss of CD95 is part of a mechanism for tumour evasion. However, complete loss of CD95 is rarely seen in human cancers4 and many cancer cells express large quantities of CD95 and are highly sensitive to CD95-mediated apoptosis in vitro. Furthermore, cancer patients frequently have elevated levels of the physiological ligand for CD95, CD95L6. These data raise the possibility that CD95 could actually promote the growth of tumours through its non-apoptotic activities7. Here we show that cancer cells in general, regardless of their CD95 apoptosis sensitivity, depend on constitutive activity of CD95, stimulated by cancer-produced CD95L, for optimal growth. Consistently, loss of CD95 in mouse models of ovarian cancer and liver cancer reduces cancer incidence as well as the size of the tumours. The tumorigenic activity of CD95 is mediated by a pathway involving JNK and Jun. These results demonstrate that CD95 has a growth-promoting role during tumorigenesis and indicate that efforts to inhibit its activity rather than to enhance it should be considered during cancer therapy.

Command and Control: Innate lymphoid cells are vital for the development of gut-associated lymphoid tissues, maintenance of the epithelial barrier, and protection against intestinal microbes; their dysfunction can promote immune pathology. Immunoglobulin A (IgA) production is important for maintenance of the gut epithelial barrier and the composition of the gut microbiota. Through the generation of knockout mouse models, Kruglov et al. (p. 1243 ) were able to distinguish how soluble and membrane-bound lymphotoxins expressed by innate lymphoid cells in the gut specifically regulate IgA production and thereby control gut microbiota composition.

Amyloid beta (Abeta) is a major contributor to the pathogenesis of Alzheimer's disease (AD). Although Abeta has been reported to be directly neurotoxic, it also causes indirect neuronal damage by activating mononuclear phagocytes (microglia) that accumulate in and around senile plaques. In this study, we show that the 42 amino acid form of beta amyloid peptide, Abeta(42), is a chemotactic agonist for a seven-transmembrane, G-protein-coupled receptor named FPR-Like-1 (FPRL1), which is expressed on human mononuclear phagocytes. Moreover, FPRL1 is expressed at high levels by inflammatory cells infiltrating senile plaques in brain tissues from AD patients. Thus, FPRL1 may mediate inflammation seen in AD and is a potential target for developing therapeutic agents.