An immature B cell population from peripheral blood serves as surrogate marker for monitoring tumor angiogenesis and anti-angiogenic therapy in mouse models

Tumor growth depends on the formation of new blood vessels (tumor angiogenesis) either from preexisting vessels or by the recruitment of bone marrow-derived cells. Despite encouraging results obtained with preclinical cancer models, the therapeutic targeting of tumor angiogenesis has thus far failed to deliver an enduring clinical response in cancer patients. One major obstacle for improving anti-angiogenic therapy is the lack of validated biomarkers, which allow patient stratification for suitable treatment and a rapid assessment of therapy response. Toward these goals, we have employed several mouse models of tumor angiogenesis to identify cell populations circulating in their blood that correlated with the extent of tumor angiogenesis and therapy response. Flow cytometry analyses of different combinations of cell surface markers that define subsets of bone marrow-derived cells were performed on peripheral blood mononuclear cells from tumor-bearing and healthy mice. We identified one cell population, CD45dimVEGFR1⁻CD31low, that was increased in levels during active tumor angiogenesis in a variety of transgenic and syngeneic transplantation mouse models of cancer. Treatment with various anti-angiogenic drugs did not affect CD45dimVEGFR1⁻CD31low cells in healthy mice, whereas in tumor-bearing mice, a consistent reduction in their levels was observed. Gene expression profiling of CD45dimVEGFR1⁻CD31low cells characterized these cells as an immature B cell population. These immature B cells were then directly validated as surrogate marker for tumor angiogenesis and of pharmacologic responses to anti-angiogenic therapies in various mouse models of cancer

Targeting Metabolic Symbiosis to Overcome Resistance to Anti-angiogenic Therapy

Despite the approval of several anti-angiogenic therapies, clinical results remain unsatisfactory, and transient benefits are followed by rapid tumor recurrence. Here, we demonstrate potent anti-angiogenic efficacy of the multi-kinase inhibitors nintedanib and sunitinib in a mouse model of breast cancer. However, after an initial regression, tumors resume growth in the absence of active tumor angiogenesis. Gene expression profiling of tumor cells reveals metabolic reprogramming toward anaerobic glycolysis. Indeed, combinatorial treatment with a glycolysis inhibitor (3PO) efficiently inhibits tumor growth. Moreover, tumors establish metabolic symbiosis, illustrated by the differential expression of MCT1 and MCT4, monocarboxylate transporters active in lactate exchange in glycolytic tumors. Accordingly, genetic ablation of MCT4 expression overcomes adaptive resistance against anti-angiogenic therapy. Hence, targeting metabolic symbiosis may be an attractive avenue to avoid resistance development to anti-angiogenic therapy in patients

An immature B cell population from peripheral blood serves as surrogate marker for monitoring tumor angiogenesis and anti-angiogenic therapy in mouse models

Tumor growth depends on the formation of new blood vessels (tumor angiogenesis) either from preexisting vessels or by the recruitment of bone marrow-derived cells. Despite encouraging results obtained with preclinical cancer models, the therapeutic targeting of tumor angiogenesis has thus far failed to deliver an enduring clinical response in cancer patients. One major obstacle for improving anti-angiogenic therapy is the lack of validated biomarkers, which allow patient stratification for suitable treatment and a rapid assessment of therapy response. Toward these goals, we have employed several mouse models of tumor angiogenesis to identify cell populations circulating in their blood that correlated with the extent of tumor angiogenesis and therapy response. Flow cytometry analyses of different combinations of cell surface markers that define subsets of bone marrow-derived cells were performed on peripheral blood mononuclear cells from tumor-bearing and healthy mice. We identified one cell population, CD45dimVEGFR1−CD31low, that was increased in levels during active tumor angiogenesis in a variety of transgenic and syngeneic transplantation mouse models of cancer. Treatment with various anti-angiogenic drugs did not affect CD45dimVEGFR1−CD31low cells in healthy mice, whereas in tumor-bearing mice, a consistent reduction in their levels was observed. Gene expression profiling of CD45dimVEGFR1−CD31low cells characterized these cells as an immature B cell population. These immature B cells were then directly validated as surrogate marker for tumor angiogenesis and of pharmacologic responses to anti-angiogenic therapies in various mouse models of cancer

VEGF receptor-2-specific signaling mediated by VEGF-E induces hemangioma-like lesions in normal and in malignant tissue

Viral VEGF-E (ovVEGF-E), a homolog of VEGF-A, was discovered in the genome of Orf virus. Together with VEGF-A, B, C, D, placental growth factor (PlGF) and snake venom VEGF (svVEGF), ovVEGF-E is a member of the VEGF family of potent angiogenesis factors with a bioactivity similar to; it induces proliferation, migration and sprouting of cultured vascular endothelial cells and proliferative lesions in the skin of sheep, goat and man that are characterized by massive capillary proliferation and dilation. These biological functions are mediated exclusively via its interaction with VEGF receptor-2 (VEGFR-2). Here, we have generated transgenic mice specifically expressing ovVEGF-E in β-cells of the endocrine pancreas (Rip1VEGF-E; RVE). RVE mice show an increase in number and size of the islets of Langerhans and a distorted organization of insulin and glucagon-expressing cells. Islet endothelial cells of RVE mice hyper-proliferate and form increased numbers of functional blood vessels. In addition, the formation of disorganized lymphatic vessels and increased immune cell infiltration is observed. Upon crossing RVE single-transgenic mice with Rip1Tag2 (RT2) transgenic mice, a well-studied model of pancreatic β-cell carcinogenesis, double-transgenic mice (RT2;RVE) display hyper-proliferation of endothelial cells resulting in the formation of hemangioma-like lesions. In addition, RT2;RVE mice exhibit activated lymphangiogenesis at the tumor periphery and increased neutrophil and macrophage tumor infiltration and micro-metastasis to lymph nodes and lungs. These phenotypes markedly differ from the phenotypes observed with the transgenic expression of the other VEGF family members in β-cells of normal mice and of RT2 mice

Angiopoietin-1 and -2 exert antagonistic functions in tumor angiogenesis, yet both induce lymphangiogenesis

Members of the Angiopoietin family regulate various aspects of physiologic and pathologic angiogenesis. Although Angiopoietin-1 (Ang-1) decreases endothelial cell permeability and increases vascular stabilization via recruitment of pericytes and smooth muscle cells to growing blood vessels, Angiopoietin-2 (Ang-2) mediates angiogenic sprouting and vascular regression. In this study, we used the Rip1Tag2 transgenic mouse model of pancreatic ?-cell carcinogenesis to investigate the roles of Ang-1 and Ang-2 in tumor angiogenesis and tumor progression. On their own, transgenic expression of human Ang-1 or Ang-2 in pancreatic ? cells caused formation of peri-insular lymphatic vessels in the absence of effects on blood vessel density, islet morphology, or physiology. When crossed to Rip1Tag2 mice, both Ang-1-and Ang-2-expressing ?-cell tumors showed increased peritumoral lymphangiogenesis in the absence of metastasis to local lymph nodes or distant organs. There was no alteration in tumor outgrowth, blood vessel density, or vessel maturation in Ang-1-expressing tumors. In contrast, Ang-2-expressing tumors exhibited diminished pericyte recruitment to blood vessels that were dilated, nonfunctional, and highly permeable. These tumors were hemorrhagic, highly infiltrated by leukocytes, and impaired in outgrowth. Together, our findings establish that Ang-2 antagonizes Ang-1 function, leading to excessive vessel sprouting with impaired pericyte recruitment and vessel stabilization. The poor perfusion of immature blood vessels results in retarded tumor growth, defining an important pathophysiologic pathway required for efficient tumorigenesis

Nintedanib Is a Highly Effective Therapeutic for Neuroendocrine Carcinoma of the Pancreas (PNET) in the Rip1Tag2 Transgenic Mouse Model

PURPOSE: Pancreatic neuroendocrine tumors (PNET) represent a rare but challenging heterogeneous group of cancers with an increasing incidence over the last number of decades. Herein, we report an in-depth evaluation of the new antiangiogenic small-molecule tyrosine kinase inhibitor (TKI) nintedanib in the preclinical Rip1Tag2 transgenic mouse model of neuroendocrine carcinoma of the pancreas (insulinoma). EXPERIMENTAL DESIGN: We have assessed the antiangiogenic and antitumor activity of nintedanib, in comparison with other antiangiogenic TKI, by treating Rip1Tag2 transgenic mice with different treatment schedules complemented with histopathologic, cell biologic, and biochemical analyses. RESULTS: Prolonged nintedanib treatment of Rip1Tag2 mice has led to a strong suppression of angiogenesis, accompanied by a reduced tumor burden, which translated into a significant prolongation of survival. Despite nintedanib's inhibitory action on perivascular cells, the blood vessels remaining after therapy displayed a considerably mature phenotype with tight perivascular cell coverage and preserved perfusion. Nintedanib treatment did not increase local tumor invasiveness or metastasis to the liver and pancreatic lymph nodes--a phenomenon that has been observed with antiangiogenic treatments of Rip1Tag2 transgenic mice in other laboratories. In contrast with the strong reduction in blood microvessel densities, nintedanib did not have any impact on tumor lymphangiogenesis. CONCLUSIONS: Based on our findings, we propose the clinical evaluation of the antiangiogenic drug nintedanib as a new treatment modality for PNET patients, notably in a direct comparison with already established therapeutic regimens, such as sunitinib

Junctional adhesion molecule B interferes with angiogenic VEGF/VEGFR2 signaling

De novo formation of blood vessels is a pivotal mechanism during cancer development. During the past few years, antiangiogenic drugs have been developed to target tumor vasculature. However, because of limitations and adverse effects observed with current therapies, there is a strong need for alternative antiangiogenic strategies. Using specific anti-junctional adhesion molecule (JAM)-B antibodies and Jam-b-deficient mice, we studied the role in antiangiogenesis of JAM-B. We found that antibodies against murine JAM-B, an endothelium-specific adhesion molecule, inhibited microvessel outgrowth from ex vivo aortic rings and in vitro endothelial network formation. In addition, anti-JAM-B antibodies blocked VEGF signaling, an essential pathway for angiogenesis. Moreover, increased aortic ring branching was observed in aortas isolated from Jam-b-deficient animals, suggesting that JAM-B negatively regulates proangiogenic pathways. In mice, JAM-B expression was detected in de novo-formed blood vessels of tumors, but anti-JAM-B antibodies unexpectedly did not reduce tumor growth. Accordingly, JAM-B deficiency in vivo had no impact on blood vessel formation, suggesting that targeting JAM-B in vivo may be offset by other proangiogenic mechanisms. In conclusion, despite the promising effects observed in vitro, targeting JAM-B during tumor progression seems to be inefficient as a stand-alone antiangiogenesis therapy.-Meguenani, M., Miljkovic-Licina, M., Fagiani, E., Ropraz, P., Hammel, P., Aurrand-Lions, M., Adams, R. H., Christofori, G., Imhof, B. A., Garrido-Urbani, S. Junctional adhesion molecule B interferes with angiogenic VEGF/VEGFR2 signaling