Primary tumor–derived systemic nANGPTL4 inhibits metastasis

Primary tumors and distant site metastases form a bidirectionally communicating system. Yet, the molecular mechanisms of this crosstalk are poorly understood. Here, we identified the proteolytically cleaved fragments of angiopoietin-like 4 (ANGPTL4) as contextually active protumorigenic and antitumorigenic contributors in this communication ecosystem. Preclinical studies in multiple tumor models revealed that the C-terminal fragment (cANGPTL4) promoted tumor growth and metastasis. In contrast, the N-terminal fragment of ANGPTL4 (nANGPTL4) inhibited metastasis and enhanced overall survival in a postsurgical metastasis model by inhibiting WNT signaling and reducing vascularity at the metastatic site. Tracing ANGPTL4 and its fragments in tumor patients detected full-length ANGPTL4 primarily in tumor tissues, whereas nANGPTL4 predominated in systemic circulation and correlated inversely with disease progression. The study highlights the spatial context of the proteolytic cleavage-dependent pro- and antitumorigenic functions of ANGPTL4 and identifies and validates nANGPTL4 as a novel biomarker of tumor progression and antimetastatic therapeutic agent

LRG1 destabilizes tumor vessels and restricts immunotherapeutic potency

Background: A poorly functioning tumor vasculature is pro-oncogenic and may impede the delivery of therapeutics. Normalizing the vasculature, therefore, may be beneficial. We previously reported that the secreted glycoprotein leucine-rich α-2-glycoprotein 1 (LRG1) contributes to pathogenic neovascularization. Here, we investigate whether LRG1 in tumors is vasculopathic and whether its inhibition has therapeutic utility. Methods: Tumor growth and vascular structure were analyzed in subcutaneous and genetically engineered mouse models in wild-type and Lrg1 knockout mice. The effects of LRG1 antibody blockade as monotherapy, or in combination with co-therapies, on vascular function, tumor growth, and infiltrated lymphocytes were investigated. Findings: In mouse models of cancer, Lrg1 expression was induced in tumor endothelial cells, consistent with an increase in protein expression in human cancers. The expression of LRG1 affected tumor progression as Lrg1 gene deletion, or treatment with a LRG1 function-blocking antibody, inhibited tumor growth and improved survival. Inhibition of LRG1 increased endothelial cell pericyte coverage and improved vascular function, resulting in enhanced efficacy of cisplatin chemotherapy, adoptive T cell therapy, and immune checkpoint inhibition (anti-PD1) therapy. With immunotherapy, LRG1 inhibition led to a significant shift in the tumor microenvironment from being predominantly immune silent to immune active. Conclusions: LRG1 drives vascular abnormalization, and its inhibition represents a novel and effective means of improving the efficacy of cancer therapeutics. Funding: Wellcome Trust (206413/B/17/Z), UKRI/MRC (G1000466, MR/N006410/1, MC/PC/14118, and MR/L008742/1), BHF (PG/16/50/32182), Health and Care Research Wales (CA05), CRUK (C42412/A24416 and A17196), ERC (ColonCan 311301 and AngioMature 787181), and DFG (CRC1366)

Angio-regulation of liver neovascularization and lung metastatic progression

Blutgefäße durchziehen den gesamten Körper und versorgen jede Zelle mit Sauerstoff und Nährstoffen. Endothelzellen (EC) stellen die innerste Zellschicht von Blutgefäßen dar, welche lange Zeit ausschließlich als inerte und passive Grenzfläche betrachtet wurde. In der letzten Dekade haben jedoch zahlreiche Forschungsergebnisse eine aktive Rolle von EC bei der Aufrechterhaltung einer physiologischen Gewebshomöostase aufgezeigt. Zusätzlich spielen angiokrine Mediatoren aus EC, die multidirektional Signale innerhalb der lokalen Gewebsmikroumgebung vermitteln, eine übergeordnete Rolle in der Wundheilung und zahlreicher pathologischer Prozesse, unter anderem bei Krebserkrankungen. Die vorliegende Studie zielte darauf ab (i) zelluläre Quellen zu ermitteln, die an der Reparatur und Erneuerung von Blutgefäßen in adulten Mäusen beteiligt sind, sowie (ii) die dynamische Evolution des Genexpressionsmusters von EC während der Progression von Tumormetastasen zu untersuchen. Um die unterschiedlichen zellulären Quellen aufzuschlüsseln, die an der vaskulären Reparatur beteiligt sind, wurde als Untersuchungsmodell eine partielle (zwei Drittel-) Hepatektomie (PHx) in adulten Mäusen durchgeführt. Die adulte Leber hat die einzigartige Fähigkeit ihre verlorene Gewebemasse innerhalb von 10 Tagen nach PHx komplett zu regenerieren. Genetische Abstammungsuntersuchungen („lineage tracing“) zeigten, dass unbeschädigte, nach PHx verbliebene Lebergefäßzellen effizient proliferieren um ein vollständig funktionelles vaskuläres Netzwerk wiederherzustellen. Im Gegensatz hierzu, führt eine Strahlenbelastung zu einer derartigen Beschädigung lokaler Leber-EC, dass Knochenmarkszellen für die vaskuläre Reparatur benötigt werden. Daher können sowohl lokale EC sowie Vorläuferzellen aus dem Knochenmark als potentielle Quellen der Lebergefäßregeneration dienen, deren relative Beteiligung von der zellulären Fitness der verbliebenen Lebervaskulatur abhängt. Um zu verstehen welche Rolle angiokrine Mediatoren bei der Etablierung einer metastatischen Nische spielen, wurde in einem fortschrittlichen Maustumormodell vergleichend sowohl das Transkriptom von Lungen-EC als auch das Serum-Proteom an verschiedenen Zeitpunkten der Metastasenprogression bestimmt. Leucine Rich alpha-2-Glycoprotein 1 (LRG1) wurde hierbei als ein EC-spezifisches Signal identifiziert, dessen Genexpressionsmuster die Abfolge einer Tumor-induzierten systemischen Entzündungsreaktion widerspiegelt. Weitere Einzelzell-Analysen von Lungen-EC sowie Multi-Organ-Gefäßanalysen offenbarten, dass LRG1 bei einer Tumorerkrankung in multiplen Gefäßbetten hochreguliert wird. Funktionell erleichtert ein systemisch erhöhter LRG1-Spiegel die metastatische Kolonisierung. Daher unterdrückt eine postoperative adjuvante Therapie mit einem LRG1-neutralisierenden Antikörper Metastasierung und verlängert das Gesamtüberleben, im Vergleich zu Kontroll-IgG-behandelten Mäusen. Insgesamt repräsentieren die erstellten Datensätze eine beispiellose Ressource um per intelligenter Datenanalyse angiokrine Mediatoren zu identifizieren, die als mögliche Zielstrukturen dienen könnten, um eine metastatische Progression zu limitieren

Preclinical validation of a novel metastasis‐inhibiting Tie1 function‐blocking antibody

Abstract The angiopoietin (Ang)–Tie pathway has been intensely pursued as candidate second‐generation anti‐angiogenic target. While much of the translational work has focused on the ligand Ang2, the clinical efficacy of Ang2‐targeting drugs is limited and failed to improve patient survival. In turn, the orphan receptor Tie1 remains therapeutically unexplored, although its endothelial‐specific genetic deletion has previously been shown to result in a strong reduction in metastatic growth. Here, we report a novel Tie1 function‐blocking antibody (AB‐Tie1‐39), which suppressed postnatal retinal angiogenesis. During primary tumor growth, neoadjuvant administration of AB‐Tie1‐39 strongly impeded systemic metastasis. Furthermore, the administration of AB‐Tie1‐39 in a perioperative therapeutic window led to a significant survival advantage as compared to control‐IgG‐treated mice. Additional in vivo experimental metastasis and in vitro transmigration assays concurrently revealed that AB‐Tie1‐39 treatment suppressed tumor cell extravasation at secondary sites. Taken together, the data phenocopy previous genetic work in endothelial Tie1 KO mice and thereby validate AB‐Tie1‐39 as a Tie1 function‐blocking antibody. The study establishes Tie1 as a therapeutic target for metastasis in a perioperative or neoadjuvant setting

Sphingosine-1-Phosphate Recruits Macrophages and Microglia and Induces a Pro-Tumorigenic Phenotype That Favors Glioma Progression

Glioblastoma is the most aggressive brain tumor in adults. Treatment failure is predominantly caused by its high invasiveness and its ability to induce a supportive microenvironment. As part of this, a major role for tumor-associated macrophages/microglia (TAMs) in glioblastoma development was recognized. Phospholipids are important players in various fundamental biological processes, including tumor–stroma crosstalk, and the bioactive lipid sphingosine-1-phosphate (S1P) has been linked to glioblastoma cell proliferation, invasion, and survival. Despite the urgent need for better therapeutic approaches, novel strategies targeting sphingolipids in glioblastoma are still poorly explored. Here, we showed that higher amounts of S1P secreted by glioma cells are responsible for an active recruitment of TAMs, mediated by S1P receptor (S1PR) signaling through the modulation of Rac1/RhoA. This resulted in increased infiltration of TAMs in the tumor, which, in turn, triggered their pro-tumorigenic phenotype through the inhibition of NFkB-mediated inflammation. Gene set enrichment analyses showed that such an anti-inflammatory microenvironment correlated with shorter survival of glioblastoma patients. Inhibition of S1P restored a pro-inflammatory phenotype in TAMs and resulted in increased survival of tumor-bearing mice. Taken together, our results establish a crucial role for S1P in fine-tuning the crosstalk between glioma and infiltrating TAMs, thus pointing to the S1P–S1PR axis as an attractive target for glioma treatment

STAT3-YAP/TAZ signaling in endothelial cells promotes tumor angiogenesis

The nuclear translocation and activity of the cotranscriptional activators YAP and TAZ (YAP/TAZ) in endothelial cells (ECs) are crucial during developmental angiogenesis. Here, we studied the role of YAP/TAZ signaling in ECs in tumor angiogenesis and found that the expression of YAP/TAZ and downstream target genes in ECs correlated with tumor vascularization in human colorectal carcinomas and skin melanoma. Treatment with the YAP/TAZ inhibitor verteporfin reduced vessel density and tumor progression in a mouse colorectal cancer (CRC) model. Conditional deletion of YAP/TAZ in ECs reduced tumor angiogenesis and growth in a mouse B16-F10 melanoma model. Using cultured ECs and mice with EC-specific ablation, we showed that signal transducer and activator of transcription 3 (STAT3) was required for the activation of YAP/TAZ in tumor-associated ECs. Moreover, we showed that STAT3-mediated signaling promoted YAP/TAZ activity and that the nuclear shuttling machinery for STAT3 was also required for YAP/TAZ nuclear translocation. Together, our data highlight the role of YAP/TAZ as critical players in ECs during tumor angiogenesis and provide insight into the signaling pathways leading to their activation

Caspase-8 in endothelial cells maintains gut homeostasis and prevents small bowel inflammation in mice

The gut has a specific vascular barrier that controls trafficking of antigens and microbiota into the bloodstream. However, the molecular mechanisms regulating the maintenance of this vascular barrier remain elusive. Here, we identified Caspase-8 as a pro-survival factor in mature intestinal endothelial cells that is required to actively maintain vascular homeostasis in the small intestine in an organ-specific manner. In particular, we find that deletion of Caspase-8 in endothelial cells results in small intestinal hemorrhages and bowel inflammation, while all other organs remained unaffected. We also show that Caspase-8 seems to be particularly needed in lymphatic endothelial cells to maintain gut homeostasis. Our work demonstrates that endothelial cell dysfunction, leading to the breakdown of the gut-vascular barrier, is an active driver of chronic small intestinal inflammation, highlighting the role of the intestinal vasculature as a safeguard of organ function