A destabilized tumor vasculature leads to limited drug delivery, hypoxia, detrimental tumor microenvironment, and even metastasis. We performed a side-by-side comparison of ABTAA (Ang2-Binding and ...Tie2-Activating Antibody) and ABA (Ang2-Blocking Antibody) in mice with orthotopically implanted glioma, with subcutaneously implanted Lewis lung carcinoma, and with spontaneous mammary cancer. We found that Tie2 activation induced tumor vascular normalization, leading to enhanced blood perfusion and chemotherapeutic drug delivery, markedly lessened lactate acidosis, and reduced tumor growth and metastasis. Moreover, ABTAA favorably altered the immune cell profile within tumors. Together, our findings establish that simultaneous Tie2 activation and Ang2 inhibition form a powerful therapeutic strategy to elicit a favorable tumor microenvironment and enhanced delivery of a chemotherapeutic agent into tumors.
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•ABTAA-induced Tie2 activation and Ang2 inhibition normalize tumor vasculature•Tumor vessel normalization leads to enhanced blood perfusion and drug delivery•Tumor vessel normalization lessens hypoxia, acidosis, tumor growth, and metastasis•Tie2 activation favorably alters the tumor microenvironment and immune infiltration
Park et al. show that an antibody that simultaneously activates Tie2 and inhibits Ang2 enhances blood perfusion and reduces tumor growth and metastasis in three different pre-clinical tumor models. Moreover, this antibody enhances therapeutic effects of chemotherapies by improving delivery to tumors.
Protection of endothelial integrity has been recognized as a frontline approach to alleviating sepsis progression, yet no effective agent for preserving endothelial integrity is available. Using an ...unusual anti-angiopoietin 2 (ANG2) antibody, ABTAA (ANG2-binding and TIE2-activating antibody), we show that activation of the endothelial receptor TIE2 protects the vasculature from septic damage and provides survival benefit in three sepsis mouse models. Upon binding to ANG2, ABTAA triggers clustering of ANG2, assembling an ABTAA/ANG2 complex that can subsequently bind and activate TIE2. Compared with a conventional ANG2-blocking antibody, ABTAA was highly effective in augmenting survival from sepsis by strengthening the endothelial glycocalyx, reducing cytokine storms, vascular leakage, and rarefaction, and mitigating organ damage. Together, our data advance the role of TIE2 activation in ameliorating sepsis progression and open a potential therapeutic avenue for sepsis to address the lack of sepsis-specific treatment.
Abstract
Upon severe head injury (HI), blood vessels of the meninges and brain parenchyma are inevitably damaged. While limited vascular regeneration of the injured brain has been studied ...extensively, our understanding of meningeal vascular regeneration following head injury is quite limited. Here, we identify key pathways governing meningeal vascular regeneration following HI. Rapid and complete vascular regeneration in the meninges is predominantly driven by VEGFR2 signaling. Substantial increase of VEGFR2 is observed in both human patients and mouse models of HI, and endothelial cell-specific deletion of
Vegfr2
in the latter inhibits meningeal vascular regeneration. We further identify the facilitating, stabilizing and arresting roles of Tie2, PDGFRβ and Dll4 signaling, respectively, in meningeal vascular regeneration. Prolonged inhibition of this angiogenic process following HI compromises immunological and stromal integrity of the injured meninges. These findings establish a molecular framework for meningeal vascular regeneration after HI, and may guide development of wound healing therapeutics.
Fetal stem cells differ phenotypically and functionally from adult stem cells in diverse tissues. However, little is known about how these differences are regulated. To address this we compared the ...gene expression profiles of fetal versus adult hematopoietic stem cells (HSCs) and discovered that the Sox17 transcriptional regulator is specifically expressed in fetal and neonatal but not adult HSCs. Germline deletion of
Sox17 led to severe fetal hematopoietic defects, including a lack of detectable definitive HSCs. Conditional deletion of
Sox17 from hematopoietic cells led to the loss of fetal and neonatal but not adult HSCs. HSCs stopped expressing
Sox17 approximately 4 weeks after birth. During this transition, loss of
Sox17 expression correlated with slower proliferation and the acquisition of an adult phenotype by individual HSCs.
Sox17 is thus required for the maintenance of fetal and neonatal HSCs and distinguishes their transcriptional regulation from adult HSCs.
Tumor progression is intimately associated with the vasculature, as tumor proliferation induces angiogenesis and tumor cells metastasize to distant organs via blood vessels. However, whether tumor ...invasion is associated with blood vessels remains unknown. As glioblastoma (GBM) is featured by aggressive invasion and vascular abnormalities, we characterized the onset of vascular remodeling in the diffuse tumor infiltrating zone by establishing new spontaneous GBM models with robust invasion capacity. Normal brain vessels underwent a gradual transition to severely impaired tumor vessels at the GBM periphery over several days. Increasing vasodilation from the tumor periphery to the tumor core was also found in human GBM. The levels of vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2) showed a spatial correlation with the extent of vascular abnormalities spanning the tumor-invading zone. Blockade of VEGFR2 suppressed vascular remodeling at the tumor periphery, confirming the role of VEGF-VEGFR2 signaling in the invasion-associated vascular transition. As angiopoietin-2 (ANGPT2) was expressed in only a portion of the central tumor vessels, we developed a ligand-independent tunica interna endothelial cell kinase 2 (Tie2)-activating antibody that can result in Tie2 phosphorylation in vivo. This agonistic anti-Tie2 antibody effectively normalized the vasculature in both the tumor periphery and tumor center, similar to the effects of VEGFR2 blockade. Mechanistically, this antibody-based Tie2 activation induced VE-PTP-mediated VEGFR2 dephosphorylation in vivo. Thus, our study reveals that the normal-to-tumor vascular transition is spatiotemporally associated with GBM invasion and may be controlled by Tie2 activation via a novel mechanism of action.
Vascular endothelial growth factor (VEGF) signaling is a key pathway for angiogenesis and requires highly coordinated regulation. Although the Notch pathway-mediated suppression of excessive VEGF ...activity via negative feedback is well known, the positive feedback control for augmenting VEGF signaling remains poorly understood. Transcription factor Sox17 is indispensable for angiogenesis, but its association with VEGF signaling is largely unknown. The contribution of other Sox members to angiogenesis also remains to be determined.
To reveal the genetic interaction of Sox7, another Sox member, with Sox17 in developmental angiogenesis and their functional relationship with VEGF signaling.
Sox7 is expressed specifically in endothelial cells and its global and endothelial-specific deletion resulted in embryonic lethality with severely impaired angiogenesis in mice, substantially overlapping with Sox17 in both expression and function. Interestingly, compound heterozygosity for Sox7 and Sox17 phenocopied vascular defects of Sox7 or Sox17 homozygous knockout, indicating that the genetic cooperation of Sox7 and Sox17 is sensitive to their combined gene dosage. VEGF signaling upregulated both Sox7 and Sox17 expression in angiogenesis via mTOR pathway. Furthermore, Sox7 and Sox17 promoted VEGFR2 (VEGF receptor 2) expression in angiogenic vessels, suggesting a positive feedback loop between VEGF signaling and SoxF.
Our findings demonstrate that SoxF transcription factors are indispensable players in developmental angiogenesis by acting as positive feedback regulators of VEGF signaling.
A key question concerns the mechanisms that determine temporal identity in stem cells. Fetal hematopoietic stem cells (HSCs) differ from adult HSCs in terms of gene expression profile, surface marker ...expression, differentiation, and self-renewal capacity. We previously showed that the transcription factor SOX17 is expressed by fetal, but not adult, HSCs and is required for the maintenance of fetal and neonatal, but not adult, HSCs. In the current study, we show that ectopic expression of Sox17 in adult HSCs and transiently reconstituting multipotent progenitors was sufficient to confer increased self-renewal potential and the expression of fetal HSC genes, including fetal HSC surface markers. Sox17 expression enabled transiently reconstituting adult progenitors to give long-term multilineage reconstitution that resembled fetal hematopoiesis, including increased erythropoiesis, increased myelopoiesis, and decreased lymphopoiesis. Long-term ectopic expression of Sox17 eventually led to leukemogenesis. These data demonstrate that SOX17 is sufficient to confer fetal HSC characteristics to adult hematopoietic progenitors and is therefore a key determinant of fetal HSC identity.
The stromal vascular fraction (SVF) in adipose tissue contains a pool of various stem and progenitor cells, but the existence of hematopoietic stem and progenitor cells (HSPCs) in the SVF has not ...been seriously considered. We detected the presence of HSPCs in the SVF by phenotypically probing with Lin−Sca-1+c-kit+ (LSK) and functionally confirming the presence using colony-forming cell assay and assessing the long-term multilineage reconstitution ability after SVF transplantation. The LSK population in the SVF was 0.004% plus or minus 0.001%, and 5 × 105 freshly isolated SVF cells gave rise to 13 plus or minus 4 multilineage colonies. In addition, 0.15% plus or minus 0.03% of SVF cells was home to bone marrow (BM), especially near vascular and endosteal regions, 24 hours after blood transplantation. SVF transplantation was capable of generating a long-term (> 16 weeks), but variable extent (2.1%-32.1%) multilineage reconstitution in primary recipients, which was subsequently transferred to the secondary recipients by BM transplantation. All HSPCs within the SVF originated from the BM. Furthermore, the granulocyte–colony-stimulating factor (G-CSF) mobilization of HSPCs from BM markedly elevated the number of phenotypic and functional HSPCs in the SVF, which induced a high efficiency long-term reconstitution in multilineage hematopoiesis in vivo. Our results provide compelling evidence that adipose tissue is a novel extramedullary tissue possessing phenotypic and functional HSPCs.
Taking aim at Sox18 Kim, Injune; Koh, Gou Young
eLife,
01/2017, Letnik:
6
Journal Article
Recenzirano
Odprti dostop
A small molecule called Sm4 can disrupt interactions involving a transcription factor called Sox18, while having little impact on other members of the SoxF family.
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