Showing papers by "Michael Detmar published in 2013"

Endocan is upregulated on tumor vessels in invasive bladder cancer where it mediates VEGF-A-induced angiogenesis.

Abstract: Tumor-associated blood vessels differ from normal vessels and proteins present only on tumor vessels may serve as biomarkers or targets for antiangiogenic therapy in cancer. Comparing the transcriptional profiles of blood vascular endothelium from human invasive bladder cancer with normal bladder tissue, we found that the endothelial cell-specific molecule endocan (ESM1) was highly elevated on tumor vessels. Endocan was associated with filopodia of angiogenic endothelial tip cells in invasive bladder cancer. Notably, endocan expression on tumor vessels correlated strongly with staging and invasiveness, predicting a shorter recurrence-free survival time in noninvasive bladder cancers. Both endocan and VEGF-A levels were higher in plasma of patients with invasive bladder cancer than healthy individuals. Mechanistic investigations in cultured blood vascular endothelial cells or transgenic mice revealed that endocan expression was stimulated by VEGF-A through the phosphorylation and activation of VEGFR-2, which was required to promote cell migration and tube formation by VEGF-A. Taken together, our findings suggest that disrupting endocan interaction with VEGFR-2 or VEGF-A could offer a novel rational strategy to inhibit tumor angiogenesis. Furthermore, they suggest that endocan might serve as a useful biomarker to monitor disease progression and the efficacy of VEGF-A-targeting therapies in patients with bladder cancer.

Blockade of VEGF receptor-3 aggravates inflammatory bowel disease and lymphatic vessel enlargement

Abstract: BACKGROUND In contrast to the prominent function of the blood vasculature in promoting tissue inflammation, the role of lymphatic vessels in inflammation has been scarcely studied in vivo. To investigate whether modulating lymphatic vessel function might affect the course of chronic inflammation, the major lymphangiogenic receptor, vascular growth factor receptor 3 (VEGFR-3, FLT4), was blocked in an established model of inflammatory bowel disease. METHODS Interleukin 10 (IL10)-deficient mice that spontaneously develop inflammatory bowel disease were treated with a blocking antibody to VEGFR-3 for 18 days, and the inflammatory changes in colon tissue and the blood and lymphatic vascularization were quantitatively analyzed. RESULTS We found a significant increase in the severity of colon inflammation in anti-VEGFR-3-treated mice. This was accompanied by an increased number of enlarged and tortuous lymphatic vessels and edema in colon submucosa, indicating impaired lymphatic function. In contrast, no major effects of the treatment on the blood vasculature were observed. CONCLUSIONS These results indicate that therapies aimed at promoting lymphatic function, e.g., with prolymphangiogenic factors, such as VEGF-C, might provide a novel strategy for the treatment of inflammatory conditions, such as inflammatory bowel disease.

VEGF-C and VEGF-D blockade inhibits inflammatory skin carcinogenesis

Abstract: VEGF-C and VEGF-D were identified as lymphangiogenic growth factors and later shown to promote tumor metastasis, but their effects on carcinogenesis are poorly understood. Here, we have studied the effects of VEGF-C and VEGF-D on tumor development in the murine multistep chemical carcinogenesis model of squamous cell carcinoma by using a soluble VEGF-C/VEGF-D inhibitor. After topical treatment with a tumor initiator and repeated tumor promoter applications, transgenic mice expressing a soluble VEGF-C/VEGF-D receptor (sVEGFR-3) in the skin developed significantly fewer squamous cell tumors with a delayed onset when compared with wild-type mice or mice expressing sVEGFR-3 lacking the ligand-binding site. Epidermal proliferation was reduced in the carcinogen-treated transgenic skin, whereas epidermal keratinocyte proliferation in vitro was not affected by VEGF-C or VEGF-D, indicating indirect effects of sVEGFR-3 expression. Importantly, transgenic mouse skin was less sensitive to tumor promoter-induced inflammation, with reduced angiogenesis and blood vessel leakage. Cutaneous leukocytes, especially macrophages, were reduced in transgenic skin without major changes in macrophage polarization or blood monocyte numbers. Several macrophage-associated cytokines were also reduced in transgenic papillomas, although the dermal macrophages themselves did not express VEGFR-3. These findings indicate that VEGF-C/VEGF-D are involved in shaping the inflammatory tumor microenvironment that regulates early tumor progression. Our results support the use of VEGF-C/VEGF-D-blocking agents not only to inhibit metastatic progression, but also during the early stages of tumor growth.

Dynamics of lymphatic regeneration and flow patterns after lymph node dissection

Abstract: Knowledge about the mechanisms of regeneration of the lymphatic vasculature after surgical trauma is essential for the development of strategies for the prevention and therapy of lymphedema. However, little is known about the alterations of lymphatic flow directly after surgical trauma. We investigated lymphatic function in mice using near-infrared imaging for a period of 4 weeks after surgeries that mimic sentinel lymph node biopsy (SLNB) or axillary lymph node dissection (ALND), by removal of the popliteal lymph node (LN) alone or together with the popliteal fat pad, respectively. SLNB-like surgery did not cause changes in lymphatic drainage in the majority of cases. In contrast, lymphatic drainage impairment shown by collecting vessel rupture, dermal backflow and rerouting of lymph flow via collateral vessels were observed after ALND-like surgery. All collateral vessels drained to the inguinal LN. These results indicate that less invasive surgery prevents lymphatic decompensation. They also reveal the development and maturation of collateral lymphatic vessels after extensive surgical trauma, which reroute the flow of lymph towards a different LN. These findings might be helpful for the development of strategies to prevent and/or treat post-surgical lymphedema.

Non-invasive dynamic near-infrared imaging and quantification of vascular leakage in vivo.

Abstract: Preclinical vascular research has been hindered by a lack of methods that can sensitively image and quantify vascular perfusion and leakage in vivo. In this study, we have developed dynamic near-infrared imaging methods to repeatedly visualize and quantify vascular leakage in mouse skin in vivo, and we have applied these methods to transgenic mice with overexpression of vascular endothelial growth factors VEGF-A or -C. Near-infrared dye conjugates were developed to identify a suitable vascular tracer that had a prolonged circulation lifetime and slow leakage into normal tissue after intravenous injection. Dynamic simultaneous imaging of ear skin and a large blood vessel in the leg enabled determination of the intravascular signal (blood volume fraction) from the tissue signal shortly after injection and quantifications of vascular leakage into the extravascular tissue over time. This method allowed for the sensitive detection of increased blood vascularity and leakage rates in K14-VEGF-A transgenic mice and also reliably measured inflammation-induced changes of vascularity and leakage over time in the same mice. Measurements after injection of recombinant VEGF-A surprisingly revealed increased blood vascular leakage and lymphatic clearance in K14-VEGF-C transgenic mice which have an expanded cutaneous lymphatic vessel network, potentially indicating unanticipated effects of lymphatic drainage on vascular leakage. Increased vascular leakage was also detected in subcutaneous tumors, confirming that the method can also be applied to deeper tissues. This new imaging method might facilitate longitudinal investigations of the in vivo effects of drug candidates, including angiogenesis inhibitors, in preclinical disease models.

Steering Target Selectivity and Potency by Fragment‐Based De Novo Drug Design

Abstract: Kinase inhibitors: Ligand-based de novo design is validated as a viable technology for rapidly generating innovative compounds possessing the desired biochemical profile. The study discloses the discovery of the most selective vascular endothelial growth factor receptor-2 (VEGFR-2) kinase inhibitor (right in scheme) known to date as prime lead for antiangiogenic drug development.

De novo design and optimization of Aurora A kinase inhibitors

Abstract: Drug discovery programs urgently seek new chemical entities that meet the needs of a demanding pharmaceutical industry. Consequently, de novo ligand design is currently re-emerging as a novelty-generating approach. Using ligand-based de novo design software, we computationally generated, chemically synthesized and biochemically tested a new arylsulfonamide against Aurora A kinase, a validated drug target in several types of cancer. The designed compound exhibited desired direct inhibitory activity against Aurora A kinase. By chemical optimization we obtained a lead structure exhibiting sustained activity in phenotypic assays. These results emphasize the potential of ligand-based de novo design to consistently deliver functional new chemotypes within short timeframes and limited effort.

In vivo imaging of lymph node lymphangiogenesis by immuno-positron emission tomography.

Abstract: Recently, our group and others found that cancer and inflammation can induce the expansion of the lymphatic vasculature (lymphangiogenesis) in draining lymph nodes in experimental animal models and in cancer patients (Hirakawa et al., J Exp Med 201:1089-1099, 2005; Qian et al., Cancer Res 66:10365-10376, 2006; Halin et al., Blood 110:3158-3167, 2007; Angeli et al., Immunity 24:203-215, 2006; Dadras et al., Mod Pathol 18:1232-1242, 2005). Since then, a growing number of reports have confirmed the importance of lymph node lymphangiogenesis in tumor metastasis, inflammation resolution, and dendritic cell migration to the lymph nodes (Angeli et al., Immunity 24:203-215, 2006; Hirakawa et al., Blood 109:1010-1017, 2007; Harrell et al., Am J Pathol 170:774-786, 2007; Kataru et al. Blood 113:5650-5659, 2009; Kataru et al., Immunity 34:96-107, 2011; Van den Eynden et al., Clin Cancer Res 13:5391-5397, 2007). Conventionally, lymphangiogenesis in mice is detected by extensive quantitative analysis of lymphatic vessels in stained tissue sections. Here we present a noninvasive methodology that we have recently developed to image lymphangiogenesis in vivo in mice (Mumprecht et al., Cancer Res 70:8842-8851, 2010). This technique is based on the intravenous injection of a radioactively labeled antibody against the lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1), which is almost exclusively expressed on lymphatic vessels (Banerji et al., J Cell Biol 144:789-801, 1999; Preyo et al., J Biol Chem 276:19420-19430, 2001). The accumulation of the injected anti-LYVE-1 antibody in the lymphatic vessels is subsequently visualized by positron emission tomography (PET). Lymphangiogenic lymph nodes emit a stronger radioactive signal than control lymph nodes because they take up more of the radiolabeled anti-LYVE-1 antibody and thus are distinguishable from normal lymph nodes in the PET images.

Abstract 3893: Endocan is upregulated on tumor vessels in invasive bladder cancer and mediates VEGF-A-induced angiogenesis.

Abstract: Tumor-associated blood vessels differ from normal vessels at the morphological and molecular level. Proteins that are only present on tumor vessels may serve as biomarkers and as therapeutic targets for inhibition of angiogenesis in cancer. To identify factors contributed by the tumor-associated endothelium, we performed immuno-laser capture microdissection (i-LCM) of blood vascular endothelial cells in conjunction with transcriptional profiling from surgically harvested cancer and normal matched bladder tissue of five patients with invasive bladder cancer. Comparing the transcriptional profiles of blood vascular endothelium from human invasive bladder cancer and from normal bladder tissue, we found that endocan (endothelial cell-specific molecule-1) was highly elevated on tumor vessels and associated with the filopodia of angiogenic endothelial tip cells in invasive bladder cancer. Notably, endocan expression on tumor vessels strongly correlated with the tumor stage and invasiveness and predicted a shorter recurrence-free survival time in non-invasive bladder cancers. Furthermore, both endocan and VEGF-A levels were significantly higher in plasma of patients with invasive bladder cancer (n=53) compared to healthy individuals (n=60). Using cultured blood vascular endothelial cells and an in vivo transgenic mouse model we found that endocan expression was strongly upregulated by VEGF-A activation of VEGFR-2. RNA interference-mediated knockdown of endocan in cultured blood vascular endothelial cells revealed that endocan was required for the promotion of cell migration and tube formation by VEGF-A. Furthermore, we found that endocan potentiates VEGFR-2 phosphorylation in response to VEGF-A. Therefore, blocking the interaction of endocan with either VEGFR-2 or VEGF-A might represent a promising approach for inhibiting tumor angiogenesis. Endocan might also serve as a novel biomarker for monitoring disease progression and the efficacy of VEGF-A-targeting therapies in patients with bladder cancer. Citation Format: Filip Roudnicky, Cedric Poyet, Peter J. Wild, Sarah Krampitz, Fabrizia Negrini, Reto Huggenberger, Anja Rogler, Robert Stohr, Arndt Hartmann, Maurizio Provenzano, Vivianne I. Otto, Michael Detmar. Endocan is upregulated on tumor vessels in invasive bladder cancer and mediates VEGF-A-induced angiogenesis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3893. doi:10.1158/1538-7445.AM2013-3893

Use of VEGF-C agonists for inhibiting ultraviolet B-induced skin damage

Abstract: This application features methods of inhibiting ultraviolet B-induced skin damage in a subject. The methods include administering a VEGF-C agonist to the subject.