Cancers are believed to arise from cancer stem cells (CSCs), but it is not known if these cells remain dependent upon the niche microenvironments that regulate normal stem cells. We show that endothelial cells interact closely with self-renewing brain tumor cells and secrete factors that maintain these cells in a stem cell-like state. Increasing the number of endothelial cells or blood vessels in orthotopic brain tumor xenografts expanded the fraction of self-renewing cells and accelerated the initiation and growth of tumors. Conversely, depletion of blood vessels from xenografts ablated self-renewing cells from tumors and arrested tumor growth. We propose that brain CSCs are maintained within vascular niches that are important targets for therapeutic approaches.

Tumors of the same histologic type often comprise clinically and molecularly distinct subgroups; however, the etiology of these subgroups is unknown. Here, we report that histologically identical, but genetically distinct, ependymomas exhibit patterns of gene expression that recapitulate those of radial glia cells in the corresponding region of the central nervous system. Cancer stem cells isolated from ependymomas displayed a radial glia phenotype and formed tumors when orthotopically transplanted in mice. These findings identify restricted populations of radial glia cells as candidate stem cells of the different subgroups of ependymoma, and they support a general hypothesis that subgroups of the same histologic tumor type are generated by different populations of progenitor cells in the tissues of origin.

AG14361 is, to our knowledge, the first high-potency PARP-1 inhibitor with the specificity and in vivo activity to enhance chemotherapy and radiation therapy of human cancer.

The incidences of chronic inflammatory disorders have increased significantly over the past three decades1. Recent shifts in dietary consumption are believed to have contributed importantly to this surge, but how dietary consumption modulates inflammatory disease is poorly defined. Pstpip2cmo mice that express a homozygous L98P missense mutation in the Pombe Cdc15 homology (PCH) family proline-serine-threonine phosphatase interacting protein 2 (PSTPIP2) phosphatase spontaneously develop osteomyelitis that resembles chronic recurrent multifocal osteomyelitis (CRMO) in humans2-4. Recent reports demonstrated osteomyelitis to critically rely on IL-1β, but deletion of the inflammasome components caspase-1 and NLRP3 failed to rescue Pstpip2cmo mice from inflammatory bone disease5,6. Thus, the upstream mechanisms controlling IL-1β production in Pstpip2cmo mice remain to be identified. In addition, the environmental factors driving IL-1β-dependent inflammatory bone erosion are unknown. Here, we show that the intestinal microbiota of diseased Pstpip2cmo mice was characterized by an outgrowth of Prevotella. Notably, Pstpip2cmo mice that were fed a diet rich in fat and cholesterol maintained a normal body weight, but were markedly protected against inflammatory bone disease and bone erosion. Diet-induced protection against osteomyelitis was accompanied by marked reductions in intestinal Prevotella levels and significantly reduced proIL-1β expression in distant neutrophils. Furthermore, proIL-1β expression was also decreased in antibiotics-treated Pstpip2cmo mice, and in wildtype mice that were kept under germfree conditions. We further demonstrated that combined deletion of caspases 1 and 8 was required for protection against IL-1β-dependent inflammatory bone disease, whereas deletion of each caspase alone, elastase or neutrophil proteinase-3 failed to prevent inflammatory disease. Collectively, this work reveals diet-associated changes in the intestinal microbiome as a critical factor regulating inflammasome- and caspase-8-mediated maturation of IL-1β and osteomyelitis in Pstpip2cmo mice.

The gene names provided in Figure 3C of this manuscript were incorrect. Images labeled Pcp4, Ppp1r1a, and Plekhb1 display RNA expression of Hoxa9, Igf1, and Fgf1, respectively.