The motility and morphogenesis of endothelial cells is controlled by spatio-temporally regulated activation of integrin adhesion receptors, and integrin activation is stimulated by major determinants of vascular remodelling. In order for endothelial cells to be responsive to changes in activator gradients, the adhesiveness of these cells to the extracellular matrix must be dynamic, and negative regulators of integrins could be required. Here we show that during vascular development and experimental angiogenesis, endothelial cells generate autocrine chemorepulsive signals of class 3 semaphorins (SEMA3 proteins) that localize at nascent adhesive sites in spreading endothelial cells. Disrupting endogenous SEMA3 function in endothelial cells stimulates integrin-mediated adhesion and migration to extracellular matrices, whereas exogenous SEMA3 proteins antagonize integrin activation. Misexpression of dominant negative SEMA3 receptors in chick embryo endothelial cells locks integrins in an active conformation, and severely impairs vascular remodelling. Sema3a null mice show vascular defects as well. Thus during angiogenesis endothelial SEMA3 proteins endow the vascular system with the plasticity required for its reshaping by controlling integrin function.

Iron metabolism in inflammation has been mostly characterized in macrophages exposed to pathogens or inflammatory conditions, mimicked by the combined action of LPS and IFN-c (M1 polarization). However, macrophages can undergo an alternative type of activation stimulated by Th2 cytokines, and acquire a role in cell growth and tissue repair control (M2 polarization). We characterized the expression of genes related to iron homeostasis in fully differentiated unpolarized (M0), M1 and M2 human macrophages. The molecular signature of the M1 macrophages showed changes in gene expression (ferroportin repression and H ferritin induction) that favour iron sequestration in the reticuloendothelial system, a hallmark of inflammatory disorders, whereas the M2 macrophages had an expression profile (ferroportin upregulation and the downregulation of H ferritin and heme oxygenase) that enhanced iron release. The conditioned media from M2 macrophages promoted cell proliferation more efficiently than those of M1 cells and the effect was blunted by iron chelation. The role of ferroportin-mediated iron release was demonstrated by the absence of differences from the media of macrophages of a patient with loss of function ferroportin mutation. The distinct regulation of iron homeostasis in M2 macrophages provides insights into their role under pathophysiological conditions. Key words: Immune system . Iron . Polarized macrophages IntroductionMacrophages play a critical role in body iron homeostasis by recovering iron from old red blood cells and returning it to the circulation for binding to transferrin, which delivers the metal to the cells that need it for various functions, thus contributing more than 80% to daily iron turnover [1][2][3].Iron retention in the reticuloendothelial system is the main response of body iron homeostasis to inflammation and is regarded as a host's attempt to withhold iron from the invading pathogens [4]. This restricts iron availability for erythroid progenitor cells and may contribute toward causing the common condition of inflammation-related anaemia [1,5,6]. Increased iron retention within inflammatory macrophages is due to increased iron uptake and decreased iron export [7], and is favoured by the induction of the iron storage protein ferritin (Ft) [8,9]. The blockade of macrophage iron release is mainly due to the interaction between the acute phase protein hepcidin and the iron exporter ferroportin (Fpn) [1][2][3], as the increase in circulating hepcidin triggered by inflammatory cytokines causes the internalization and degradation of Fpn [10], the exporter of non-heme iron [11], thus blocking iron release from macrophages.Macrophage Fpn is also negatively regulated at transcriptional and post-transcriptional levels by inflammatory mediators [12][13][14]. It is still unknown whether the inflammatory response affects the feline leukemia virus, subgroup C, receptor that exports heme from macrophages [15] and whether the heme transporter HRG1 proteins play a role in macrophage iron metabolism [16]. O...

Tumor-associated macrophages (TAMs) are key orchestrators of the tumor microenvironment directly affecting neoplastic cell growth, neoangiogenesis, and extracellular matrix remodeling. In turn, the tumor milieu strongly influences maturation of TAMs and shapes several of their features. To address the early macrophage (Mϕ) differentiation phase in a malignant context, we mimicked a tumor microenvironment by in vitro coculturing human blood monocytes with conditioned media from different cancer cell lines. Only 2 out of 16 tumor cell lines induced Mϕ differentiation due to secreted M-CSF isoforms, including high molecular mass species. A global gene profiling of tumor-conditioned Mϕ was performed. Comparison with other datasets (polarized M1-Mϕ, M2-Mϕ, and TAMs isolated from human tumors) highlighted the upregulation of several genes also shared by TAM and M2-polarized Mϕ. The most expressed genes were selenoprotein 1, osteoactivin, osteopontin, and, interestingly, migration-stimulating factor (MSF), a poorly studied oncofoetal isoform of fibronectin. MSF (present in fetal/cancer epithelial and stromal cells but not in healthy tissues) was never identified in Mϕ. MSF production was confirmed by immunohistochemistry in human TAMs. MSF was induced by M-CSF, IL-4, and TGFβ but not by proinflammatory stimuli. RNA and protein analysis clearly demonstrated that it is specifically associated with the M2 polarization of Mϕ. Tumor-conditioned Mϕ-derived MSFs strongly stimulated tumor cell migration, thus contributing to the motile phenotype of neoplastic cells. In conclusion, MSF is a new molecule associated with the M2 polarization of Mϕ and expressed by TAMs. Its biological function may contribute to Mϕ-mediated promotion of cancer cell invasion and metastasis.

In response to microenvironmental signals, macrophages undergo different activation, including the "classic" proinflammatory phenotype (also called M1), the "alternative" activation induced by the IL-4/IL-13 trigger, and the related but distinct heterogeneous M2 polarization associated with the anti-inflammatory profile. The latter is induced by several stimuli, including IL-10 and TGF-␤. Macrophagepolarized activation has profound effects on immune and inflammatory responses and in tumor biology, but information on the underlying molecular pathways is scarce. In the present study, we report that alternative polarization of macrophages requires the transcription factor c-MYC. In macrophages, IL-4 and different stimuli sustaining M2-like polarization induce c-MYC expression and its translocation to the nucleus. c-MYC controls the induction of a subset (45%) of genes associated with alternative activation. ChIP assays indicate that c-MYC directly regulates some genes associated with alternative activation, including SCARB1, ALOX15, and MRC1, whereas others, including CD209, are indirectly regulated by c-MYC. c-MYC up-regulates the IL-4 signaling mediators signal transducer and activator of transcription-6 and peroxisome proliferator-activated receptor␥, is also expressed in tumorassociated macrophages, and its inhibition blocks the expression of protumoral genes including VEGF, MMP9, HIF-1␣, and TGF-␤. We conclude that c-MYC is a key player in alternative macrophage activation, and is therefore a potential therapeutic target in pathologies related to these cells, including tumors. (Blood. 2012;119(2):411-421) IntroductionMacrophages are specialized phagocytic cells involved in multiple processes, both in homeostatic conditions and during the immune response after tissue damage or exposure to a pathogen. Macrophages are characterized by a striking heterogeneity, which can be partially ascribed to their origin by self-renewal of resident postmitotic cells and by monocyte subsets recruited and differentiated locally. 1-3 A second element shaping macrophage heterogeneity is the microenvironment, both under homeostatic conditions, with the hosting tissue profoundly influencing macrophage differentiation, and in the context of an inflammatory or immune response, which generates a wide range of polarized activation states. [3][4][5][6] Activation with IFN-␥, alone or in combination with pathogen-derived signals such as lipopolysaccharide (LPS), leads to classically activated macrophages, also referred to as M1 cells, which develop proinflammatory type 1 immune responses. Macrophage exposure to other immune signals results in profoundly different functional phenotypes. These include "alternatively activated" macrophages caused by IL-4/IL-13 stimulation, which are associated with type 2 immune responses and a spectrum of functional phenotypes related to anti-inflammatory, angiogenic, and tissue-repair properties induced in macrophages by stimuli including TGF-␤, immune complexes, glucocorticoids, and IL-10. 3,4,6,7 Further...

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The bone morphogenic protein antagonist gremlin is expressed during embryonic development and under different pathologic conditions, including cancer. Gremlin is a proangiogenic protein belonging to the cystine-knot superfamily that includes transforming growth factor-␤ proteins and the angiogenic vascu- IntroductionThe bone morphogenic protein (BMP) antagonist gremlin 1 induces angiogenesis in a BMP-independent manner by binding to as-yetunidentified endothelial cell (EC) membrane receptors and activating multiple tyrosine kinase-dependent intracellular signaling pathways in ECs. 2,3 Gremlin is produced by human tumors 4,5 and is expressed by fibroblast growth factor-2 (FGF2)-activated ECs and tumor endothelium. 2 Thus, gremlin may play paracrine/autocrine roles in tumor neovascularization. The identification of the EC receptors activated by gremlin has so far been unsuccessful.Vascular endothelial growth factor receptor-2 (VEGFR2) is the major proangiogenic tyrosine kinase receptor expressed by ECs and is activated by different members of the vascular endothelial growth factor (VEGF) family. 6 Both gremlin and VEGFs belong to the cystine-knot protein superfamily, 7 suggesting possible structural and/or functional similarities among these proangiogenic factors. On this basis, we investigated the capacity of gremlin to interact with and activate VEGFR2. The results demonstrate that gremlin binds and activates VEGFR2, leading to VEGFR2-dependent angiogenic responses in vitro and in vivo. Methods Ligand-receptor interaction assaysInteraction of VEGF-A and gremlin (R&D Systems) with the immobilized extracellular domain of VEGFR2 (sVEGFR2; Calbiochem) was analyzed by surface plasmon resonance (BIAcore Inc) and by competitive enzymelinked immunosorbent assay (ELISA). VEGFR2 interaction on the EC surface was characterized by cross-linking experiments, whereas VEGFR2 dimerization was assessed by fluorescence resonance energy transfer analysis. In vitro angiogenic assaysMotility and 3-dimensional gel invasion assays were performed on human, murine, and bovine ECs. 3 When indicated, ECs were stably transfected with a pcDNA3.1 expression vector harboring the mouse VEGFR2 complementary DNA.

Carcinosarcomas (CSs) of the uterus and ovary are highly aggressive neoplasms containing both carcinomatous and sarcomatous elements. We analyzed the mutational landscape of 68 uterine and ovarian CSs by whole-exome sequencing. We also performed multiregion whole-exome sequencing comprising two carcinoma and sarcoma samples from six tumors to resolve their evolutionary histories. The results demonstrated that carcinomatous and sarcomatous elements derive from a common precursor having mutations typical of carcinomas. In addition to mutations in cancer genes previously identified in uterine and ovarian carcinomas such as TP53, PIK3CA, PPP2R1A, KRAS, PTEN, CHD4, and BCOR, we found an excess of mutations in genes encoding histone H2A and H2B, as well as significant amplification of the segment of chromosome 6p harboring the histone gene cluster containing these genes. We also found frequent deletions of the genes TP53 and MBD3 (a member with CHD4 of the nucleosome remodeling deacetylase complex) and frequent amplification of chromosome segments containing the genes PIK3CA, TERT, and MYC. Stable transgenic expression of H2A and H2B in a uterine serous carcinoma cell line demonstrated that mutant, but not wild-type, histones increased expression of markers of epithelial-mesenchymal transition (EMT) as well as tumor migratory and invasive properties, suggesting a role in sarcomatous transformation. Comparison of the phylogenetic relationships of carcinomatous and sarcomatous elements of the same tumors demonstrated separate lineages leading to these two components. These findings define the genetic landscape of CSs and suggest therapeutic targets for these highly aggressive neoplasms.uterine carcinosarcoma | ovarian carcinosarcoma | exome sequencing C arcinosarcomas (CSs) of the female genital tract, also known as mixed malignant Müllerian tumors, are rare but highly aggressive tumors characterized by a biphasic histology. These cancers most commonly arise in the uterus, followed by the ovaries, fallopian tubes, and vagina (1-3). The diagnosis of CS requires the presence of both sarcomatous and carcinomatous components. Although the pathogenesis of CSs remains under debate, an increasing body of evidence supports the origin of both elements from a common epithelial cell that undergoes sarcomatous dedifferentiation, rather than two independent progenitors (2-5).The overall 5-y survival is only 30 ± 9% for all stages, and the recurrence rate after surgery is extremely high (50-80%) (3-5). The uncertain origin and poor prognosis of uterine and ovarian CSs motivate determination of the molecular basis of CS aggressive behavior in the hope of developing novel and effective treatment modalities. ResultsThe Genetic Landscape of CS. A total of 68 patients with stage I-IV uterine (n = 44) and ovarian (n = 24) CSs were studied. Their clinical and histological features are presented in SI Appendix, Table S1. Upon surgical removal of tumors, primary cell lines were prepared (five tumors) or tumors were frozen (63 tumors). Among t...

(2011) Epigenetic investigation of variably X chromosome inactivated genes in monozygotic female twins discordant for primary biliary cirrhosis , Epigenetics, 6:1, 95-102,