The question whether tumorigenic cancer stem cells exist in human melanomas has arisen recently1. Here we show that in melanomas, tumor stem cells (MTSC) can be isolated prospectively as a highly enriched CD271+ MTSC population using a process that maximizes viable cell transplantation1,6. In this study the tumors sampled were taken from a broad spectrum of sites and stages. High viability FACS isolated cells resuspended in a matrigel vehicle were implanted into T, B, and NK deficient Rag2−/− γc−/− mice (RG) mice. The CD271+ subset of cells was the tumor initiating population in 9/10 melanomas tested. Transplantation of isolated melanoma cells into engrafted human skin or bone in RG mice resulted in melanoma from CD271+ but not CD271− cells. We also showed that tumors transplanted by CD271+ patient cells were capable of metastasis in-vivo. Importantly, CD271+ melanoma cells lacked expression of TYR, MART and MAGE in 86%, 69% and 68% of melanoma patients respectively suggesting why T cell therapies directed at these antigens usually result in only temporary tumor shrinkage.

Akt kinases control essential cellular functions, including proliferation, apoptosis, metabolism and transcription, and have been proposed as promising targets for treatment of angiogenesis-dependent pathologies, such as cancer and ischemic injury. But their precise roles in neovascularization remain elusive. Here we show that Akt1 is the predominant isoform in vascular cells and describe the unexpected consequences of Akt1 knockout on vascular integrity and pathological angiogenesis. Angiogenic responses in three distinct in vivo models were enhanced in Akt1(-/-) mice; these enhanced responses were associated with impairment of blood vessel maturation and increased vascular permeability. Although impaired vascular maturation in Akt1(-/-) mice may be attributed to reduced activation of endothelial nitric oxide synthase (eNOS), the major phenotypic changes in vascular permeability and angiogenesis were linked to reduced expression of two endogenous vascular regulators, thrombospondins 1 (TSP-1) and 2 (TSP-2). Re-expression of TSP-1 and TSP-2 in mice transplanted with wild-type bone marrow corrected the angiogenic abnormalities in Akt1(-/-) mice. These findings establish a crucial role of an Akt-thrombospondin axis in angiogenesis.

Monogenic deficiency diseases provide unique opportunities to define the contributions of individual molecules to human physiology and to identify pathologies arising from their dysfunction. Here we describe a deficiency disease in two human siblings that presented with severe bleeding, frequent infections and osteopetrosis at an early age. These symptoms are consistent with but more severe than those reported for people with leukocyte adhesion deficiency III (LAD-III). Mechanistically, these symptoms arose from an inability to activate the integrins expressed on hematopoietic cells, including platelets and leukocytes. Immortalized lymphocyte cell lines isolated from the two individuals showed integrin activation defects. Several proteins previously implicated in integrin activation, including Ras-associated protein-1 (RAP1) 1 and calcium and diacylglycerol-regulated guanine nucleotide exchange factor-1 (CALDAG-GEF1) 2 , were present and functional in these cell lines. The genetic basis for this disease was traced to a point mutation in the coding region of the KINDLIN3 (official gene symbol FERMT3) gene 3 . When wild-type KINDLIN-3 was expressed in the immortalized lymphocytes, their integrins Correspondence should be addressed to T.V.B. (byzovat@ccf.org). 6 These authors contributed equally to this work.Note: Supplementary information is available on the Nature Medicine website. AUTHOR CONTRIBUTIONS N.L.M. identified the Kindlin-3 mutation, performed molecular biology and protein biochemistry studies and wrote the manuscript; L.Z. contributed to study design and experiments on primary leukocytes from subjects; J.C. performed assays with EGFP-Kindlin-3 rescue and siRNA-mediated KINDLIN3 knockdown and western blotting; A.C. performed microscopy studies and FACS analysis; O.R. performed cell culture work and molecular biology; Y.-Q.M. performed molecular biology and Kindlin-3-specific antibody preparation; E.A.P. performed platelet studies; M.T. performed neutrophil analysis; D.P.L. and A.I.C. performed osteogenesis assays; S.B.S. originally described the subjects, designed clinical studies and wrote the manuscript; E.F.P. designed the studies, interpreted the results and wrote the manuscript; T.V.B. performed experiments with platelets and leukocytes, designed the general strategy, interpreted data and wrote the manuscript. Kindlin-3 is one of the three-member kindlin family of intracellular proteins that are linked to the actin cytoskeleton 3 . The family is evolutionarily conserved with an ortholog, UNC-112, found in Caenorhabditis elegans 4 . Each kindlin contains a C-terminal FERM domain that is most similar to that of talin, another cytoskeletal protein involved in integrin regulation. Kindlins and talin bind to nonoverlapping sites in the cytoplasmic tails of integrins 5 . Kindler disease, associated with a deficiency of Kindlin-1, has multiple symptoms, including skin blistering and poikiloderma 6 . Kindlin-2 deficiency is embryonically lethal in zebrafish and mice but has not been described in hu...