101
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García-Román J, Zentella-Dehesa A. Vascular permeability changes involved in tumor metastasis. Cancer Lett 2013; 335:259-69. [DOI: 10.1016/j.canlet.2013.03.005] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2013] [Revised: 03/05/2013] [Accepted: 03/06/2013] [Indexed: 12/12/2022]
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102
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Angiopoietin-2 expression is correlated with angiogenesis and overall survival in oral squamous cell carcinoma. Med Oncol 2013; 30:571. [PMID: 23649549 DOI: 10.1007/s12032-013-0571-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 04/02/2013] [Indexed: 02/05/2023]
Abstract
This study sought to determine the expression of angiopoietin-2 (Ang-2) and vascular endothelial cell growth factor (VEGF) in oral squamous cell carcinoma (OSCC) and assess their correlations with tumor progression, angiogenesis, vessel maturation, and clinical survival. Tumor tissue from 102 OSCC patients, adjacent noncancerous oral tissue from 79 OSCC patients, and normal oral mucosa from 35 control patients were examined for Ang-2 and VEGF expression using conventional immunohistochemistry. Microvessel density (MVD) and vessel maturation index (VMI) were assessed by double-label immunohistochemistry staining using anti-CD34 and anti-alpha-smooth muscle actin, respectively. Although the proportion of OSCC samples positive for Ang-2 or VEGF expression was significantly higher than that observed in the adjacent noncancerous tissue and normal oral mucosa (P < 0.001), neither Ang-2 nor VEGF expression was associated with the clinicopathological parameters analyzed in OSCC patients. However, MVD and VMI were significantly associated with the expression of Ang-2 (P = 0.001 and P = 0.014, respectively); VEGF expression was associated MVD (P = 0.004). The MVD of OSCC tissues expressing both Ang-2 and VEGF was significantly higher than observed in the double-negative samples (P < 0.05). Multivariate regression and Kaplan-Meier analyses revealed that Ang-2 was negatively associated with the overall survival of OSCC patients. Expression of Ang-2 was associated with angiogenesis and vessel maturation in OSCC. Further studies will evaluate the prognostic value of determining Ang-2 expression in OSCC.
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103
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Eroglu Z, Stein CA, Pal SK. Targeting angiopoietin-2 signaling in cancer therapy. Expert Opin Investig Drugs 2013; 22:813-25. [DOI: 10.1517/13543784.2013.793306] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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104
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Eklund L, Saharinen P. Angiopoietin signaling in the vasculature. Exp Cell Res 2013; 319:1271-80. [PMID: 23500414 DOI: 10.1016/j.yexcr.2013.03.011] [Citation(s) in RCA: 175] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2012] [Revised: 03/03/2013] [Accepted: 03/04/2013] [Indexed: 01/26/2023]
Abstract
The angiopoietin (Ang) growth factors and the endothelial Tie receptors regulate blood and lymphatic vessel development, and vascular permeability, inflammation, angiogenic remodeling and tumor vascularization in adult tissues. The angiopoietins activate the Tie receptors in unique in trans complexes at endothelial cell-cell and cell-matrix contacts. In addition, integrins have been implicated in the regulation of Ang-Tie signaling. Recent interest has focused on the function of angiopoietin-2 and its inhibition in the tumor vasculature and also in other pathological conditions associated with endothelial dysfunction. Here we review the current understanding of the signaling functions of the Ang-Tie pathway and its potential for future development of targeted vascular therapeutics.
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Affiliation(s)
- Lauri Eklund
- Oulu Center for Cell-Matrix Research, Biocenter Oulu, and Department of Medical Biochemistry and Molecular Biology, University of Oulu, Finland
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105
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Thomas M, Kienast Y, Scheuer W, Bähner M, Kaluza K, Gassner C, Herting F, Brinkmann U, Seeber S, Kavlie A, Welschof M, Ries S, Weidner KM, Regula JT, Klein C. A novel angiopoietin-2 selective fully human antibody with potent anti-tumoral and anti-angiogenic efficacy and superior side effect profile compared to Pan-Angiopoietin-1/-2 inhibitors. PLoS One 2013; 8:e54923. [PMID: 23405099 PMCID: PMC3566157 DOI: 10.1371/journal.pone.0054923] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 12/19/2012] [Indexed: 11/29/2022] Open
Abstract
There is increasing experimental evidence for an important role of Angiopoietin-2 (Ang-2) in tumor angiogenesis and progression. In addition, Ang-2 is up-regulated in many cancer types and correlated with poor prognosis. To investigate the functional role of Ang-2 inhibition in tumor development and progression, we generated novel fully human antibodies that neutralize specifically the binding of Ang-2 to its receptor Tie2. The selected antibodies LC06 and LC08 recognize both rodent and human Ang-2 with high affinity, but LC06 shows a higher selectivity for Ang-2 over Ang-1 compared to LC08 which can be considered an Ang-2/Ang-1 cross-reactive antibody. Our data demonstrate that Ang-2 blockade results in potent tumor growth inhibition and pronounced tumor necrosis in subcutaneous and orthotopic tumor models. These effects are attended with a reduction of intratumoral microvessel density and tumor vessels characterized by fewer branches and increased pericyte coverage. Furthermore, anti-Ang-2 treatment strongly inhibits the dissemination of tumor cells to the lungs. Interestingly, in contrast to the Ang-2/Ang-1 cross-reactive antibody LC08 that leads to a regression of physiological vessels in the mouse trachea, the inhibition with the selective anti-Ang-2 antibody LC06 appears to be largely restricted to tumor vasculature without obvious effects on normal vasculature. Taken together, these data provide strong evidence for the selective Ang-2 antibody LC06 as promising new therapeutic agent for the treatment of various cancers.
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Affiliation(s)
- Markus Thomas
- Discovery Oncology, Pharma Research and Early Development, Roche Diagnostics GmbH, Penzberg, Germany.
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106
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Im JH, Tapmeier T, Balathasan L, Gal A, Yameen S, Hill S, Smart S, Noterdaeme O, Kelly M, Brady M, Fu W, Kruse K, Bernhard EJ, Augustin HG, Muschel RJ. G-CSF rescues tumor growth and neo-angiogenesis during liver metastasis under host angiopoietin-2 deficiency. Int J Cancer 2013; 132:315-26. [PMID: 22699974 DOI: 10.1002/ijc.27677] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Revised: 05/11/2012] [Accepted: 05/16/2012] [Indexed: 01/12/2023]
Abstract
Suppression of neo-angiogenesis is a clinically used anti-tumor strategy with new targets such as angiopoietin-2 (Ang2) being proposed. However, the functions of Ang2 in vascular remodeling, inflammation and tumor growth are not consistent. We examined effect of depletion of host Ang2 on liver colony formation using Ang2 deficient (Ang2(-/-)) mice. Surprisingly, the metastatic colonies formed in Ang2(-/-) mice were larger than those in the wild type. These colonies had greater vascular density with more pericyte coverage than the vessels in liver colonies in the wild type. Liver VEGF concentration in both genotypes was equivalent, and thus, the differences appeared VEGF independent. However, after colony formation, the serum concentration of granulocyte-colony stimulating factor (G-CSF) and CXCL1 in Ang2(-/-) mice was 12 and 6 times greater than after colony formation in wild type. Increase of these two cytokines was associated with two times greater numbers of neutrophils recruited to the liver. Two times more Tie2+/CD11b+/CD31- cells were present in the tumors in Ang2(-/-) than in the wild type livers. These results suggest that the depletion of host Ang2 induced compensatory VEGF-independent angiogenic mechanisms and thus enhanced liver metastatic colony growth and colony vascularity. They further indicate organotypic differences in response to tumor metastasis. In contrast, Ang2 deficiency inhibited tumor growth during metastatic colony formation in the lung, consistent with the reports of decreased pulmonary seeding of tumor cells after pharmacological inhibition of Ang2. Further studies are thus required to assess the effects of pharmacological Ang2 blockade for cancer patients particularly in the liver.
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Affiliation(s)
- Jae Hong Im
- Gray Institute for Radiation Oncology and Biology, University of Oxford, Oxford, United Kingdom
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107
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Molnar N, Siemann DW. Combined Ang-2 and VEGF Targeting Therapies in Renal Cell Carcinoma. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/jct.2013.49a2001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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108
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Interfering growth of malignant melanoma with Ang2-siRNA. Mol Biol Rep 2012; 40:1463-71. [PMID: 23160899 PMCID: PMC3538013 DOI: 10.1007/s11033-012-2189-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Accepted: 10/09/2012] [Indexed: 11/03/2022]
Abstract
To investigate the intervention therapy effect on the growth of malignant melanoma, we have made an observation of expression levels of Ang2 in malignant melanoma cells, which was transduced by small interfering RNA (Ang2-siRNA) of Ang2 in vitro and in vivo. We successfully constructed Ang2-siRNA lent virus, and constructed nude mice model by transplanting malignant melanoma. Ang2-siRNA lent virus inhibited Ang2 mRNA of malignant melanoma in vitro and in vivo, and inhibited malignant melanoma tumor growth at the same time. Ang2-siRNA lent virus can interfere expression levels of Ang2 in malignant melanoma cells, inhibit tumor growth, and silent Ang2 gene expression, which may pave a new way for clinical gene therapy of malignant melanoma.
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109
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Daly C, Eichten A, Castanaro C, Pasnikowski E, Adler A, Lalani AS, Papadopoulos N, Kyle AH, Minchinton AI, Yancopoulos GD, Thurston G. Angiopoietin-2 functions as a Tie2 agonist in tumor models, where it limits the effects of VEGF inhibition. Cancer Res 2012; 73:108-18. [PMID: 23149917 DOI: 10.1158/0008-5472.can-12-2064] [Citation(s) in RCA: 168] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The angiopoietins Ang1 (ANGPT1) and Ang2 (ANGPT2) are secreted factors that bind to the endothelial cell-specific receptor tyrosine kinase Tie2 (TEK) and regulate angiogenesis. Ang1 activates Tie2 to promote blood vessel maturation and stabilization. In contrast, Ang2, which is highly expressed by tumor endothelial cells, is thought to inhibit Tie2 activity and destabilize blood vessels, thereby facilitating VEGF-dependent vessel growth. Here, we show that the inhibition of tumor xenograft growth caused by an Ang2-specific antibody (REGN910) is reversed by systemic administration of the Tie2 agonist Ang1. These results indicate that Ang2 blockade inhibits tumor growth by decreasing Tie2 activity, showing that Ang2 is a Tie2 activator. REGN910 treatment of tumors resulted in increased expression of genes that are repressed by Tie2 activation, providing further evidence that REGN910 inhibits Tie2 signaling. Combination treatment with REGN910 plus the VEGF blocker aflibercept reduced tumor vascularity and tumor perfusion more dramatically than either single agent, resulting in more extensive tumor cell death and more potent inhibition of tumor growth. Challenging the prevailing model of Ang2 as a destabilizing factor, our findings indicate that Ang2 plays a protective role in tumor endothelial cells by activating Tie2, thereby limiting the antivascular effects of VEGF inhibition. Thus, blockade of Ang2 might enhance the clinical benefits currently provided by anti-VEGF agents. .
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110
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Thurston G, Daly C. The complex role of angiopoietin-2 in the angiopoietin-tie signaling pathway. Cold Spring Harb Perspect Med 2012; 2:a006550. [PMID: 22951441 DOI: 10.1101/cshperspect.a006650] [Citation(s) in RCA: 169] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The angiopoietin-Tie signaling system is a vascular-specific receptor tyrosine kinase pathway that is essential for normal vascular development. Although the basic functioning of the pathway is understood, many uncertainties remain about the role of certain members of the pathway, particularly angiopoietin-2 (Ang2), in pathological vascular remodeling and angiogenesis. We summarize the components of the angiopoietin-Tie pathway and then focus on studies that highlight the role of Ang2 in disease settings, including cancer and inflammation. The expression of Ang2 is elevated in many cancers and types of inflammation, which prompted the development of specific reagents to block its interaction with the Tie2 receptor. The application of these reagents in preclinical models of inflammation and cancer has begun to elucidate the role of Ang2 in vascular remodeling and disease pathogenesis and has led to emerging clinical tests of Ang2 inhibitors.
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111
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Angiopoietins in angiogenesis. Cancer Lett 2012; 328:18-26. [PMID: 22922303 DOI: 10.1016/j.canlet.2012.08.018] [Citation(s) in RCA: 438] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 08/14/2012] [Accepted: 08/14/2012] [Indexed: 12/26/2022]
Abstract
Tie-1 and Tie-2 tyrosine kinase receptors are expressed specifically on vascular endothelial cells and on a certain subtype of macrophages implicated in angiogenesis, thus, they have been a major focus of angiogenesis research. Tie-1 and Tie-2 are essential for vascular maturation during developmental, physiological and pathological angiogenesis. Angiopoietin 1-4 (Ang-1-4) have been identified as bona fide ligands of the Tie-2 receptor, while Tie-1 remains an orphan receptor which is able to heterodimerize with Tie-2 and to modulate Tie-2 signal transduction. The most exhaustively studied angiopoietins are Ang-1 and Ang-2. Ang-1 is a critical player in vessel maturation and it mediates migration, adhesion and survival of endothelial cells. Ang-2 disrupts the connections between the endothelium and perivascular cells and promotes cell death and vascular regression. Yet, in conjunction with VEGF, Ang-2 promotes neo-vascularization. Hence, angiopoietins exert crucial roles in the angiogenic switch during tumor progression, and increased expression of Ang-2 relative to Ang-1 in tumors correlates with poor prognosis. Its central role in the regulation of physiological and pathological angiogenesis makes the angiopoietin/Tie signaling pathway a therapeutically attractive target for the treatment of vascular disease and cancer.
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112
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Gardizi M, Kurschat C, Riese A, Hahn M, Krieg T, Mauch C, Kurschat P. A decreased ratio between serum levels of the antagonistic angiopoietins 1 and 2 indicates tumour progression of malignant melanoma. Arch Dermatol Res 2012; 304:397-400. [DOI: 10.1007/s00403-012-1228-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Revised: 02/28/2012] [Accepted: 02/29/2012] [Indexed: 01/11/2023]
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113
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Molnar N, Siemann DW. Inhibition of endothelial/smooth muscle cell contact loss by the investigational angiopoietin-2 antibody MEDI3617. Microvasc Res 2012; 83:290-7. [PMID: 22387475 DOI: 10.1016/j.mvr.2012.02.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Revised: 02/13/2012] [Accepted: 02/14/2012] [Indexed: 02/05/2023]
Abstract
A tumor's dependence on angiogenesis for survival and growth has led to the advancement of a variety of blood vessel directed anticancer treatment strategies. Overexpression of angiopoietin-2 (Ang-2) in tumor vasculature and its crucial role in angiogenesis, i.e. the destabilization of endothelial/peri-endothelial cell interactions, now raises the possibility of additional novel anti-angiogenic therapeutics. The present study utilized a co-culture sphere model to (i) demonstrate the destabilizing effect of Ang-2 on endothelial/smooth muscle cell contact and (ii) evaluate the impact of the investigational Ang-2 antibody MEDI3617 on endothelial/smooth muscle cell dissociation. Real time imaging of spheres showed both exogenous Ang-2 and PMA induced endogenous Ang-2 secretion resulted in sphere destabilization (loss of endothelial cells from smooth muscle cell core). The presence of MEDI3617 inhibited this process. To assess the anti-angiogenic potential of MEDI3617 in vivo, nude mice were injected intradermally with human renal cell carcinoma cells (Caki-1, Caki-2) and the number of blood vessels induced over a 3 day period was scored. MEDI3617 (2, 10, 20 mg/kg) significantly reduced the initiation of blood vessels for both tumor models at all doses investigated. These data indicate that MEDI3617 treatment significantly impairs the initiation of angiogenesis by inhibiting the Ang-2 mediated disruption of endothelial/muscle cell interaction associated with blood vessel destabilization and thereby reduces tumor cell induced angiogenesis. The results support the notion that targeting the angiopoietin/Tie2 axis may offer novel anti-angiogenic strategies for cancer treatment.
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MESH Headings
- Angiogenesis Inhibitors/pharmacology
- Angiopoietin-2/biosynthesis
- Angiopoietin-2/chemistry
- Animals
- Antibodies/chemistry
- Antibodies, Monoclonal/pharmacology
- Antibodies, Monoclonal, Humanized
- Carcinoma, Renal Cell/metabolism
- Coculture Techniques
- Dose-Response Relationship, Drug
- Endothelium, Vascular/cytology
- Endothelium, Vascular/drug effects
- Enzyme-Linked Immunosorbent Assay/methods
- Human Umbilical Vein Endothelial Cells
- Humans
- Mice
- Mice, Nude
- Microcirculation
- Myocytes, Smooth Muscle/cytology
- Myocytes, Smooth Muscle/drug effects
- Neoplasm Transplantation
- Neoplasms/drug therapy
- Neovascularization, Pathologic
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Affiliation(s)
- Nikolett Molnar
- Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, FL 32610, USA.
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114
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Tumor lymphangiogenesis as a potential therapeutic target. JOURNAL OF ONCOLOGY 2012; 2012:204946. [PMID: 22481918 PMCID: PMC3307004 DOI: 10.1155/2012/204946] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 10/10/2011] [Accepted: 10/31/2011] [Indexed: 12/18/2022]
Abstract
Metastasis the spread of cancer cells to distant organs, is the main cause of death for cancer patients. Metastasis is often mediated by lymphatic vessels that invade the primary tumor, and an early sign of metastasis is the presence of cancer cells in the regional lymph node (the first lymph node colonized by metastasizing cancer cells from a primary tumor). Understanding the interplay between tumorigenesis and lymphangiogenesis (the formation of lymphatic vessels associated with tumor growth) will provide us with new insights into mechanisms that modulate metastatic spread. In the long term, these insights will help to define new molecular targets that could be used to block lymphatic vessel-mediated metastasis and increase patient survival. Here, we review the molecular mechanisms of embryonic lymphangiogenesis and those that are recapitulated in tumor lymphangiogenesis, with a view to identifying potential targets for therapies designed to suppress tumor lymphangiogenesis and hence metastasis.
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115
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Zhou J, Zhang ZX, Zhao H, Zhu DM, Zhang Y, Li DC. Anti-angiogenesis by lentivirus-mediated small interfering RNA silencing of angiopoietin-2 gene in pancreatic carcinoma. Technol Cancer Res Treat 2012; 10:361-9. [PMID: 21728393 DOI: 10.7785/tcrt.2012.500213] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Angiopoietin-2 (Ang2) has been shown highly expressed in resected human pancreatic carcinoma samples, but the role of it is less clear. We were, therefore, interested in exploring the effects of Ang2 silencing on the angiogenesis and growth of pancreatic carcinoma. Lentivirus mediated Ang2 small hairpin RNA (LV-RNAi) were transfected into pancreatic carcinoma cell line MIA PaCa-2. Three groups were designed in this study: the control group (Mia PaCa-2 cells), the LV-NC group (cells transfected with the control GFP-lentivirus) and the LV-RNAi group (cells transfected with LV-RNAi). The mRNA and protein level of Ang2 gene were detected by real-time polymerase chain reaction and Western blot respectively. MTT assay and Flow Cytometry were used to detect the cell growth and apoptosis. Anti-angiogenesis effect was measured by chick embryo chorioallantoic membrane (CAM) assay. In nude mice bearing tumors, after treatment with intratumoral injection of LV-RNAi, mice growth and tumor volume were observed, and the expression of Ang2, VEGF and CD34 were measured by immunohistochemistry. Compared with the control group and the LV-NC group, the mRNA and protein level of Ang2 gene were successfully knocked down in LV- RNAi group. Also the vessel count was decreased in CAM assay after LV-RNAi transfection. Meanwhile, no obvious cell viability and apoptosis changes were found in MTT assay and Flow Cytometry, respectively. LV-RNAi inhibited pancreatic carcinoma angio- genesis and growth by downregulating the expression of VEGF and CD34. These findings demonstrate that Ang2 gene silencing may exert a anti-angiogenesis effect in vitro and in vivo, and Ang2 targeted gene therapy has the potential to serve as a novel way for pancreatic carcinoma treatment.
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Affiliation(s)
- J Zhou
- Department of General Surgery, the First Affiliated Hospital of Soochow University, 188 Shizi Road, Suzhou 21500, China
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116
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Cascone T, Heymach JV. Targeting the angiopoietin/Tie2 pathway: cutting tumor vessels with a double-edged sword? J Clin Oncol 2011; 30:441-4. [PMID: 22184396 DOI: 10.1200/jco.2011.38.7621] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Affiliation(s)
- Tina Cascone
- The University of Texas MD Anderson Cancer Center, Unit 432, 1515 Holcombe Blvd, Houston, TX 77030, USA
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117
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van der Veldt AAM, Vroling L, de Haas RR, Koolwijk P, van den Eertwegh AJM, Haanen JBAG, van Hinsbergh VWM, Broxterman HJ, Boven E. Sunitinib-induced changes in circulating endothelial cell-related proteins in patients with metastatic renal cell cancer. Int J Cancer 2011; 131:E484-93. [PMID: 21953673 DOI: 10.1002/ijc.26456] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Accepted: 09/01/2011] [Indexed: 11/06/2022]
Abstract
Vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitors are effective agents in the treatment of metastatic renal cell cancer (mRCC). We here investigated whether inhibition of VEGFR signalin by sunitinib causes changes in plasma proteins associated with tumor endothelium. Forty-three patients with mRCC received sunitinib 50 mg/day in a 4-weeks on 2-weeks off schedule. Sequential plasma samples were obtained before treatment (C1D1), on C1D14, on C1D28, and on C2D1 before start of cycle 2. Plasma levels were assessed for VEGF, soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble intercellular cell adhesion molecule-1 (sICAM-1), von Willebrand factor (vWF), circulating angiopoietin-2 (Ang-2) and soluble Tie-2 (sTie-2). Total tumor burden was calculated at baseline and at first evaluation. Progression-free survival (PFS) and overall survival (OS) were determined. Tumor burden was positively associated with baseline circulating Ang-2 [Spearman's rho (ρ) = 0.378, p = 0.028] and vWF (ρ = 0.417, p = 0.008). During sunitinib treatment, circulating Ang-2 and sTie-2 significantly decreased (p < 0.001 for both), plasma levels of sVCAM-1 and VEGF significantly increased (p = 0.022 and p < 0.001), whereas those of sICAM-1 and vWF remained stable. These protein changes had recovered on C2D1. The reduction in circulating Ang-2 levels on C1D28 was positively correlated with the percentage decrease in tumor burden (ρ = 0.605; p = 0.002). Baseline protein levels and subsequent changes were not associated with PFS or OS. In conclusion, sunitinib-induced changes in Ang-2, sTie-2, sVCAM-1 and VEGF are related to the administration schedule, while reduction in Ang-2 is also associated with decrease in tumor burden.
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118
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Vascular disruption and the role of angiogenic proteins after spinal cord injury. Transl Stroke Res 2011; 2:474-91. [PMID: 22448202 PMCID: PMC3296011 DOI: 10.1007/s12975-011-0109-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2011] [Revised: 09/20/2011] [Accepted: 09/25/2011] [Indexed: 02/06/2023]
Abstract
Spinal cord injuries (SCI) can result in devastating paralysis, for which there is currently no robustly efficacious neuroprotective/neuroregenerative treatment. When the spinal cord is subjected to a traumatic injury, the local vasculature is disrupted and the blood–spinal cord barrier is compromised. Subsequent inflammation and ischemia may then contribute to further secondary damage, exacerbating neurological deficits. Therefore, understanding the vascular response to SCI and the molecular elements that regulate angiogenesis has considerable relevance from a therapeutic standpoint. In this paper, we review the nature of vascular damage after traumatic SCI and what is known about the role that angiogenic proteins—angiopoietin 1 (Ang1), angiopoietin 2 (Ang2) and angiogenin—may play in the subsequent response. To this, we add recent work that we have conducted in measuring these proteins in the cerebrospinal fluid (CSF) and serum after acute SCI in human patients. Intrathecal catheters were installed in 15 acute SCI patients within 48 h of injury. CSF and serum samples were collected over the following 3–5 days and analysed for Ang1, Ang2 and angiogenin protein levels using a standard ELISA technique. This represents the first description of the endogenous expression of these proteins in an acute human SCI setting.
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119
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The Role of PTEN in Tumor Angiogenesis. JOURNAL OF ONCOLOGY 2011; 2012:141236. [PMID: 21904550 PMCID: PMC3167192 DOI: 10.1155/2012/141236] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Accepted: 07/01/2011] [Indexed: 01/08/2023]
Abstract
During the past 20 years, the phosphatase and tensin homolog PTEN has been shown to be involved in major physiological processes, and its mutation or loss is often associated with tumor formation. In addition PTEN regulates angiogenesis not only through its antagonizing effect on the PI3 kinase pathway mainly, but also through some phosphatase-independent functions. In this paper we delineate the role of this powerful tumor suppressor in tumor angiogenesis and dissect the underlying molecular mechanisms. Furthermore, it appears that, in a number of cancers, the PTEN status determines the response to chemotherapy, highlighting the need to monitor PTEN expression and to develop PTEN-targeted therapies.
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120
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Schulz P, Fischer C, Detjen KM, Rieke S, Hilfenhaus G, von Marschall Z, Böhmig M, Koch I, Kehrberger J, Hauff P, Thierauch KH, Alves F, Wiedenmann B, Scholz A. Angiopoietin-2 drives lymphatic metastasis of pancreatic cancer. FASEB J 2011; 25:3325-35. [PMID: 21685330 DOI: 10.1096/fj.11-182287] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Lymphatic metastasis constitutes a critical route of disease dissemination, which limits the prognosis of patients with pancreatic ductal adenocarcinoma (PDAC). As lymphangiogenesis has been implicated in stimulation of lymphatic metastasis by vascular endothelial growth factor-C (VEGF-C) and VEGF-D, we studied the effect of the angioregulatory growth factor angiopoietin-2 (Ang-2) on PDAC progression. Ang-2 was found to be expressed in transformed cells of human PDAC specimens, with corresponding Tie-2 receptors present on blood and lymphatic endothelium. In vitro in PDAC cells, Ang-2 was subject to autocrine/paracrine TGF-β stimulation (2-fold induction, P=0.0106) acting on the -61- to +476-bp element of the human Ang-2 promoter. In turn, Ang-2 regulated the expression of genes involved in cell motility and tumor suppression. Orthotopic PDAC xenografts with forced expression of Ang-2, but not Ang-1, displayed increased blood and lymphatic vessel density, and an enhanced rate of lymphatic metastasis (6.7- to 9.1-fold, P<0.01), which was prevented by sequestration of Ang-2 via coexpression of soluble Tie-2. Notably, elevated circulating Ang-2 in patients with PDAC correlated with the extent of lymphatic metastasis. Furthermore, median survival was reduced from 28.4 to 7.7 mo in patients with circulating Ang-2 ≥ 75th percentile (P=0.0005). These findings indicate that Ang-2 participates in the control of lymphatic metastasis, constitutes a noninvasive prognostic biomarker, and may provide an accessible therapeutic target in PDAC.
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Affiliation(s)
- Petra Schulz
- Medizinische Klinik mit Schwerpunkt Hepatologie und Gastroenterologie, Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, D-13353 Berlin, Germany
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121
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Imanishi Y, Hu B, Xiao G, Yao X, Cheng SY. Angiopoietin-2, an angiogenic regulator, promotes initial growth and survival of breast cancer metastases to the lung through the integrin-linked kinase (ILK)-AKT-B cell lymphoma 2 (Bcl-2) pathway. J Biol Chem 2011; 286:29249-29260. [PMID: 21680733 DOI: 10.1074/jbc.m111.235689] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The early onsets of breast cancer metastasis involve cell retention, survival, and resistant to apoptosis and subsequent growth at target vascular beds and tissues in distant organs. We previously reported that angiopoietin-2 (Ang2), an angiogenic regulator stimulates MCF-7 breast tumor metastasis from their orthotopic sites to distant organs through the α(5)β(1) integrin/integrin-linked kinase (ILK)/Akt pathway. Here, by using an experimental tumor metastasis model and in vitro studies, we further dissect the underlying mechanism by which Ang2 promotes the initial growth and survival of MCF-7 breast cancer metastasis in the lung of animals. We show that Ang2 increases cell survival and suppresses cell apoptosis through ILK-induced phosphorylation of Akt1, Akt2, and up-regulation of Bcl-2 in breast cancer cells. Inhibition of ILK, Akt1, and Akt2, and their effector Bcl-2 diminishes Ang2-stimulated breast cancer cell survival and Ang2-attenuated apoptosis in vitro, and initial survival and growth of breast cancer metastasis in the lung of animals. Additionally, siRNA knockdown of endogenous Ang2 in three human metastatic breast cancer cell lines also inhibits phosphorylation of Akt, expression of Bcl-2, and tumor cell survival, migration, and increases cell apoptosis. Since increased expression of Ang2 correlates with elevated potential of human breast cancer metastasis in clinic, our data underscore the importance that up-regulated Ang2 not only stimulates breast cancer growth and metastasis at late stages of the process, but is also critical at the initiating stages of metastases onset, thereby suggesting Ang2 as a promising therapeutic target for treating patients with metastatic breast cancer.
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Affiliation(s)
- Yorihisa Imanishi
- Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213; Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213; Department of Otorhinolaryngology, Head and Neck Surgery, Keio University, School of Medicine, Shinjuku, Tokyo 160-8582, Japan
| | - Bo Hu
- Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213; Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213.
| | - Gutian Xiao
- Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213; Department of Microbiology & Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213
| | - Xuebiao Yao
- Anhui Laboratory of Cellular Dynamics and Chemical Biology, Hefei National Laboratory for Physical Sciences at Nanoscale, Hefei 230027, China, and; Department of Physiology, Morehouse School of Medicine, Atlanta, Georgia 30310
| | - Shi-Yuan Cheng
- Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213; Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213.
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122
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Leong SPL, Gershenwald JE, Soong SJ, Schadendorf D, Tarhini AA, Agarwala S, Hauschild A, Soon CWM, Daud A, Kashani-Sabet M. Cutaneous melanoma: a model to study cancer metastasis. J Surg Oncol 2011; 103:538-49. [PMID: 21480247 DOI: 10.1002/jso.21816] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Nodal status in melanoma is a critically important prognostic factor for patient outcome. The survival rate drops to <10% when melanoma has spread beyond the regional lymph nodes and includes visceral involvement. In general, the process of melanoma metastasis is progressive in that dissemination of melanoma from the primary site to the regional lymph nodes occurs prior to systemic disease. The goal of this review article is to describe melanoma as a clinical model to study cancer metastasis. A future challenge is to develop a molecular taxonomy to subgroup melanoma patients at various stages of tumor progression for more accurate targeted treatment.
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Affiliation(s)
- Stanley P L Leong
- Center for Melanoma Research and Treatment and Department of Surgery, California Pacific Medical Center and Research Institute, San Francisco, California 94115, USA.
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123
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Rykala J, Przybylowska K, Majsterek I, Pasz-Walczak G, Sygut A, Dziki A, Kruk-Jeromin J. Angiogenesis markers quantification in breast cancer and their correlation with clinicopathological prognostic variables. Pathol Oncol Res 2011; 17:809-17. [PMID: 21560015 PMCID: PMC3185224 DOI: 10.1007/s12253-011-9387-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Accepted: 03/09/2011] [Indexed: 12/29/2022]
Abstract
Tumoural angiogenesis is essential for the growth and spread of breast cancer cells. Therefore the aim of this study was to assess the diagnostic performance of angiogenesis markers in tumours and there reflecting levels in serum of breast cancer patients. Angiogenin, Ang2, fibroblast growth factor basic, intercellular adhesion molecule (ICAM)-1, keratinocyte growth factor (KGF), platelet-derived growth factor-BB, and VEGF-A were measured using a FASTQuant angiogenic growth factor multiplex protein assay. We observed that breast cancer tumours exhibited high levels of PDGF-BB, bFGF and VEGF, and extremely high levels of TIMP-1 and Ang-2, whereas in serum we found significantly higher levels of Ang-2, PDGF-BB, bFGF, ICAM-1 and VEGF in patients with breast cancer compared to the benign breast diseases patients. Moreover, some of these angiogenesis markers evaluated in tumour and serum of breast cancer patients exhibited association with standard clinical parameters, ER status as well as MVD of tumours. Angiogenesis markers play important roles in tumour growth, invasion and metastasis. Our results suggest that analysis of angiogenesis markers in tumour and serum of breast cancer patients using multiplex protein assay can improve diagnosis and prognosis in this diseases.
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Affiliation(s)
- Jan Rykala
- Department of Plastic, Reconstructive and Aesthetic Surgery, Barlicki Hospital, Medical University of Lodz, Kopcinskiego 22, 90-153, Lodz, Poland.
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124
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Saharinen P, Eklund L, Pulkki K, Bono P, Alitalo K. VEGF and angiopoietin signaling in tumor angiogenesis and metastasis. Trends Mol Med 2011; 17:347-62. [PMID: 21481637 DOI: 10.1016/j.molmed.2011.01.015] [Citation(s) in RCA: 333] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Revised: 01/24/2011] [Accepted: 01/28/2011] [Indexed: 12/12/2022]
Abstract
Solid tumors require blood vessels for growth and dissemination, and lymphatic vessels as additional conduits for metastatic spread. The identification of growth factor receptor pathways regulating angiogenesis has led to the clinical approval of the first antiangiogenic molecules targeted against the vascular endothelial growth factor (VEGF)-VEGF receptor (VEGFR)-2 pathway. However, in many cases resistance to anti-VEGF-VEGFR therapy occurs, and thus far the clinical benefit has been limited to only modest improvements in overall survival. Therefore, novel treatment modalities are required. Here, we discuss the members of the VEGF-VEGFR family as well as the angiopoietin growth factors and their Tie receptors as potential novel targets for antiangiogenic and antilymphangiogenic therapies.
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Affiliation(s)
- Pipsa Saharinen
- Molecular/Cancer Biology, Research Programs Unit, Biomedicum Helsinki, P.O.B. 63, (Haartmaninkatu 8), FIN-00014, University of Helsinki, Finland
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125
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Gan L, Chen S, Zhong J, Wang X, Lam EKY, Liu X, Zhang J, Zhou T, Yu J, Si J, Wang L, Jin H. ZIC1 is downregulated through promoter hypermethylation, and functions as a tumor suppressor gene in colorectal cancer. PLoS One 2011; 6:e16916. [PMID: 21347233 PMCID: PMC3039653 DOI: 10.1371/journal.pone.0016916] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2010] [Accepted: 01/03/2011] [Indexed: 01/07/2023] Open
Abstract
The transcription factor, Zinc finger of the cerebellum (ZIC1), plays a crucial role in vertebrate development. Recently, ZIC1 has also been found to participate in the progression of human cancers, including medulloblastomas, endometrial cancers, and mesenchymal neoplasms. However, the function of ZIC1 in colon cancer progression has not been defined. In this study, we demonstrate ZIC1 to be silenced or significantly downregulated in colon cancer cell lines. These effects were reversed by demethylation treatment with 5-aza-2'-deoxycytidine (Aza). ZIC1 expression is also significantly downregulated in primary colorectal cancer tissues relative to adjacent non-tumor tissues (p = 0.0001). Furthermore, methylation of ZIC1 gene promoter is frequently detected in primary tumor tissues (85%, 34/40), but not in adjacent non-tumor tissues. Ectopic expression of ZIC1 suppresses cell proliferation and induces apoptosis, which is associated with MAPK and PI(3)K/Akt pathways, as well as the Bcl-xl/Bad/Caspase3 cascade. To identify target candidates of ZIC1, we employed cDNA microarray and found that 337 genes are downregulated and 95 genes upregulated by ectopic expression of ZIC1, which were verified by 10 selected gene expressions by qRT-PCR. Taken together, our results suggest that ZIC1 may potentially function as a tumor suppressor gene, which is downregulated through promoter hypermethylation in colorectal cancers.
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Affiliation(s)
- Lihong Gan
- Department of Gastroenterology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Shujie Chen
- Laboratory of Digestive Disease, Clinical Institution of Sir Run Run Shaw Hospital, Zhejiang University, Hangzhou, China
| | - Jing Zhong
- Department of Gastroenterology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Xian Wang
- Key Laboratory of Biotherapy of Zheijang Province, Biomedical Research Center, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Emily K. Y. Lam
- Department of Medicine and Therapeutics, Institute of Digestive Disease, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong, SAR China
| | - Xin Liu
- Department of Medicine and Therapeutics, Institute of Digestive Disease, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong, SAR China
| | - Jianbin Zhang
- Department of Medicine and Therapeutics, Institute of Digestive Disease, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong, SAR China
| | - Tianhua Zhou
- Department of Cell Biology and Program in Molecular Cell Biology, School of Medicine Zhejiang University, Hangzhou, China
| | - Jun Yu
- Department of Medicine and Therapeutics, Institute of Digestive Disease, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong, SAR China
| | - Jianmin Si
- Laboratory of Digestive Disease, Clinical Institution of Sir Run Run Shaw Hospital, Zhejiang University, Hangzhou, China
| | - Liangjing Wang
- Department of Gastroenterology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
- * E-mail:
| | - Hongchuan Jin
- Key Laboratory of Biotherapy of Zheijang Province, Biomedical Research Center, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China
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Helfrich I, Schadendorf D. Blood vessel maturation, vascular phenotype and angiogenic potential in malignant melanoma: one step forward for overcoming anti-angiogenic drug resistance? Mol Oncol 2011; 5:137-49. [PMID: 21345752 DOI: 10.1016/j.molonc.2011.01.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Accepted: 01/27/2011] [Indexed: 12/15/2022] Open
Abstract
Angiogenesis is a pivotal process for growth, invasion and spread of the majority of solid tumors including melanoma. Anti-angiogenic agents have not been systematically tested in patients with advanced melanoma. Clinical efficacy of angiogenesis inhibitors targeting endothelial cells has not been as affirmative as initially hoped and improved clinical outcomes have been observed in combination with chemotherapy or additional drugs for many types of human cancer. However, angiogenesis is not only dependent on endothelial cell invasion and proliferation, it also requires pericyte coverage of vascular sprouts for stabilization and maturation of vascular walls. Recent data suggest that pericytes might be able to confer resistance to anti-vascular endothelial growth factor (VEGF) therapy. This review will focus on the significance of the vascular phenotype but also on the impact of pericyte-mediated vessel maturation for the susceptibility to anti-angiogenic therapy, including malignant melanoma, which we identified as crucial factor regarding therapeutic efficacy.
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Affiliation(s)
- Iris Helfrich
- Department of Dermatology, University Hospital Essen, Hufelandstrasse 55, D-45122 Essen, Germany
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127
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Abstract
Bispecific antibodies (BsAbs) are regarded as promising therapeutic agents due to their ability to simultaneously bind two different antigens. Several bispecific modalities have been developed, but their utility is limited due to problems with stability and manufacturing complexity. Here we report a versatile technology, based on a scaffold antibody and pharmacophore peptide heterodimers, that enables rapid generation and chemical optimization of bispecific antibodies, which are termed bispecific CovX-Bodies. Two different peptides are joined together using a branched azetidinone linker and fused to the scaffold antibody under mild conditions in a site-specific manner. Whereas the pharmacophores are responsible for functional activities, the antibody scaffold imparts long half-life and Ig-like distribution. The pharmacophores can be chemically optimized or replaced with other pharmacophores to generate optimized or unique bispecific antibodies. As a prototype, we developed a bispecific antibody that binds both vascular endothelial growth factor (VEGF) and angiopoietin-2 (Ang2) simultaneously, inhibits their function, shows efficacy in tumor xenograft studies, and greatly augments the antitumor effects of standard chemotherapy. This unique antiangiogenic bispecific antibody is in phase-1 clinical trials.
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128
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Volkova E, Willis JA, Wells JE, Robinson BA, Dachs GU, Currie MJ. Association of angiopoietin-2, C-reactive protein and markers of obesity and insulin resistance with survival outcome in colorectal cancer. Br J Cancer 2010; 104:51-9. [PMID: 21081932 PMCID: PMC3039823 DOI: 10.1038/sj.bjc.6606005] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Background: This study investigated the relationship of obesity, insulin resistance, inflammation and angiogenesis with cancer progression and survival in a colorectal cancer cohort. Methods: Clinical and pathological data, along with anthropometric and follow-up data, were collected from 344 consecutive colorectal cancer patients. Serum samples at diagnosis were analysed by immunoassay for adiponectin, C-reactive protein (CRP), vascular endothelial growth factor-A (VEGF-A), angiopoietin-2 (Ang-2), insulin-like growth factor-1 (IGF-1), insulin and C-peptide. Results: Serum Ang-2 and VEGF-A levels increased with tumour T stage (P=0.007 and P=0.025, respectively) and N stage (P=0.02 and P=0.03, respectively), and correlated with CRP levels (r=0.43, P<0.001 and r=0.23, P<0.001, respectively). Angiopoietin-2 correlated with C-peptide (r=0.14, P=0.007) and VEGF-A with IGF-1 in males (r=0.25, P=0.001). Kaplan–Meier analysis showed that patients with high serum levels of CRP and Ang-2 had significantly reduced survival (both P⩽0.001). After adjusting for tumour stage and age, Ang-2 remained a significant predictor of survival. The CRP levels were inversely associated with survival in American Joint Committee on Cancer stage II patients (P=0.038), suggesting that CRP could be used to support treatment decisions in this subgroup. Serum markers and anthropometric measures of obesity correlated with each other, but not with survival. Conclusion: Our study supports the concept that obesity-related inflammation, rather than obesity itself, is associated with colorectal cancer progression and survival. The study confirms serum Ang-2 as a predictive marker for outcome of colorectal cancer.
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Affiliation(s)
- E Volkova
- Angiogenesis and Cancer Research Group, Department of Pathology, University of Otago Christchurch, PO Box 4345, Christchurch 8140, New Zealand
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129
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Goede V, Coutelle O, Neuneier J, Reinacher-Schick A, Schnell R, Koslowsky TC, Weihrauch MR, Cremer B, Kashkar H, Odenthal M, Augustin HG, Schmiegel W, Hallek M, Hacker UT. Identification of serum angiopoietin-2 as a biomarker for clinical outcome of colorectal cancer patients treated with bevacizumab-containing therapy. Br J Cancer 2010; 103:1407-14. [PMID: 20924372 PMCID: PMC2990609 DOI: 10.1038/sj.bjc.6605925] [Citation(s) in RCA: 131] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Background: The combination of chemotherapy with the vascular endothelial growth factor (VEGF) antibody bevacizumab is a standard of care in advanced colorectal cancer (CRC). However, biomarkers predicting outcome of bevacizumab-containing treatment are lacking. As angiopoietin-2 (Ang-2) is a key regulator of vascular remodelling in concert with VEGF, we investigated its role as a biomarker in metastatic CRC. Methods: Serum Ang-2 levels were measured in 33 healthy volunteers and 90 patients with CRC. Of these, 34 had metastatic disease and received bevacizumab-containing therapy. To determine the tissue of origin of Ang-2, quantitative real-time PCR was performed on microdissected cryosections of human CRC and in a murine xenograft model of CRC using species-specific amplification. Results: Ang-2 originated from the stromal compartment of CRC tissues. Serum Ang-2 levels were significantly elevated in patients with metastatic CRC compared with healthy controls. Amongst patients receiving bevacizumab-containing treatment, low pre-therapeutic serum Ang-2 levels were associated with a significant better response rate (82 vs 31% P<0.01), a prolonged median progression-free survival (14.1 vs 8.5 months; P<0.01) and a reduction of 91% in the hazard of death (P<0.05). Conclusion: Serum Ang-2 is a candidate biomarker for outcome of patients with metastatic CRC treated with bevacizumab-containing therapy, and it should be further validated to customise combined chemotherapeutic and anti-angiogenic treatment.
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Affiliation(s)
- V Goede
- Department of Internal Medicine I, Center of Integrated Oncology Cologne-Bonn, University Hospital Cologne, Kerpener Straße 62, Cologne 50924, Germany
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130
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Li Y, Chen J, Wu C, Wang L, Lu M, Chen X. Hepatitis B virus/hepatitis C virus upregulate angiopoietin-2 expression through mitogen-activated protein kinase pathway. Hepatol Res 2010; 40:1022-33. [PMID: 20887338 DOI: 10.1111/j.1872-034x.2010.00712.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
AIM To explore the molecular mechanism of hepatitis B virus (HBV)/hepatitis C virus (HCV) upregulate angiopoietin-2 (Ang-2) expression. METHODS Reverse transcription polymerase chain reaction (RT-PCR), quantitative real-time (qRT)-PCR and enzyme-linked immunosorbent assay (ELISA) analysis were used to measure the Ang-2 transcription and expression level. Reporter gene assays were used to determine the cis-element of the Ang-2 promoter. The specific inhibitors assay, immunofluorescence and western blot analysis were conducted to verify the signal pathway involved in the upregulation of Ang-2 expression. RESULTS The level of transcription and expression of Ang-2 increased in the HepG2.2.15 and Con-1 cells. Reporter gene assays in HepG2.2.15 and Con-1 cells revealed that HBV/HCV could enhance Ang-2 promoter expression by activating AP-1 and Ets1. Analysis with specific inhibitors indicated that HBV/HCV upregulated the expression of Ang-2 through mitogen-activated protein kinase (MAPK) pathways. CONCLUSION This study illustrates a distinct mechanism by which a tumor virus modulates vasculature to promote tumorigenesis.
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Affiliation(s)
- Yanmei Li
- State Key Lab of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China Institute of Virology, University Hospital of Essen, Essen, Germany
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131
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Trollope AF, Golledge J. Angiopoietins, abdominal aortic aneurysm and atherosclerosis. Atherosclerosis 2010; 214:237-43. [PMID: 20832800 DOI: 10.1016/j.atherosclerosis.2010.08.051] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Revised: 06/29/2010] [Accepted: 08/02/2010] [Indexed: 01/10/2023]
Abstract
Abdominal aortic aneurysm (AAA) and atherosclerosis are common causes of mortality and morbidity in an aging population. Angiogenesis is believed to contribute to the development and progression of these diseases. Angiopoietins (angpts) are known to be important regulators of angiogenesis. Angpts can also influence inflammation and have been shown to possess both pro-atherosclerotic and atheroprotective effects. This review explores the potential roles that the angpts play in the development and progression of AAA and atherosclerosis.
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Affiliation(s)
- Alexandra F Trollope
- The Vascular Biology Unit, School of Medicine and Dentistry, James Cook University, Douglas Campus, Townsville, QLD 4811, Australia
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132
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Abstract
Angiopoietins (ANGPTs) are ligands of the endothelial cell receptor TIE2 and have crucial roles in the tumour angiogenic switch. Increased expression of ANGPT2 relative to ANGPT1 in tumours correlates with poor prognosis. The biological effects of the ANGPT-TIE system are context dependent, which brings into question what the best strategy is to target this pathway. This Review presents an encompassing picture of what we know about this important axis in tumour biology. The various options for therapeutic intervention are discussed to identify the best path forwards.
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133
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Coffelt SB, Tal AO, Scholz A, De Palma M, Patel S, Urbich C, Biswas SK, Murdoch C, Plate KH, Reiss Y, Lewis CE. Angiopoietin-2 regulates gene expression in TIE2-expressing monocytes and augments their inherent proangiogenic functions. Cancer Res 2010; 70:5270-80. [PMID: 20530679 DOI: 10.1158/0008-5472.can-10-0012] [Citation(s) in RCA: 247] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
TIE2-expressing monocytes/macrophages (TEM) are a highly proangiogenic subset of myeloid cells in tumors. Here, we show that circulating human TEMs are already preprogrammed in the circulation to be more angiogenic and express higher levels of such proangiogenic genes as matrix metalloproteinase-9 (MMP-9), VEGFA, COX-2, and WNT5A than TIE2(-) monocytes. Additionally, angiopoietin-2 (ANG-2) markedly enhanced the proangiogenic activity of TEMs and increased their expression of two proangiogenic enzymes: thymidine phosphorylase (TP) and cathepsin B (CTSB). Three "alternatively activated" (or M2-like) macrophage markers were also upregulated by ANG-2 in TEMs: interleukin-10, mannose receptor (MRC1), and CCL17. To investigate the effects of ANG-2 on the phenotype and function of TEMs in tumors, we used a double-transgenic (DT) mouse model in which ANG-2 was specifically overexpressed by endothelial cells. Syngeneic tumors grown in these ANG-2 DT mice were more vascularized and contained greater numbers of TEMs than those in wild-type (WT) mice. In both tumor types, expression of MMP-9 and MRC1 was mainly restricted to tumor TEMs rather than TIE2(-) macrophages. Furthermore, tumor TEMs expressed higher levels of MRC1, TP, and CTSB in ANG-2 DT tumors than WT tumors. Taken together, our data show that although circulating TEMs are innately proangiogenic, exposure to tumor-derived ANG-2 stimulates these cells to exhibit a broader, tumor-promoting phenotype. As such, the ANG-2-TEM axis may represent a new target for antiangiogenic cancer therapies.
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Affiliation(s)
- Seth B Coffelt
- Academic Unit of Inflammation and Tumour Targeting, University of Sheffield Medical School, Sheffield, United Kingdom
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134
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Thomas M, Felcht M, Kruse K, Kretschmer S, Deppermann C, Biesdorf A, Rohr K, Benest AV, Fiedler U, Augustin HG. Angiopoietin-2 stimulation of endothelial cells induces alphavbeta3 integrin internalization and degradation. J Biol Chem 2010; 285:23842-9. [PMID: 20519501 DOI: 10.1074/jbc.m109.097543] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The angiopoietins (Ang-1 and Ang-2) have been identified as agonistic and antagonistic ligands of the endothelial receptor tyrosine kinase Tie2, respectively. Both ligands have been demonstrated to induce translocation of Tie2 to cell-cell junctions. However, only Ang-1 induces Tie2-dependent Akt activation and subsequent survival signaling and endothelial quiescence. Ang-2 interferes negatively with Ang-1/Tie2 signaling, thereby antagonizing the Ang-1/Tie2 axis. Here, we show that both Ang-1 and Ang-2 recruit beta3 integrins to Tie2. This co-localization is most prominent in cell-cell junctions. However, only Ang-2 stimulation resulted in complex formation among Tie2, alphavbeta3 integrin, and focal adhesion kinase as evidenced by co-immunoprecipitation experiments. Focal adhesion kinase was phosphorylated in the FAT domain at Ser(910) upon Ang-2 stimulation and the adaptor proteins p130Cas and talin dissociated from alphavbeta3 integrin. The alphavbeta3 integrin was internalized, ubiquitinylated, and gated toward lysosomes. Taken together, the experiments define Tie2/alphavbeta3 integrin association-induced integrin internalization and degradation as mechanistic consequences of endothelial Ang-2 stimulation.
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Affiliation(s)
- Markus Thomas
- Joint Research Division Vascular Biology, Medical Faculty Mannheim (CBTM), Heidelberg University, D-69120 Heidelberg, Germany
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135
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Basu B, Biswas S, Wrigley J, Sirohi B, Corrie P. Angiogenesis in cutaneous malignant melanoma and potential therapeutic strategies. Expert Rev Anticancer Ther 2010; 9:1583-98. [PMID: 19895243 DOI: 10.1586/era.09.135] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Metastatic melanoma (MM) carries a dismal prognosis, as it is largely resistant to conventional cytotoxic chemotherapy, biochemotherapy and immunotherapy. There is, therefore, a pressing need to identify new, effective treatments to improve outcomes from MM. Innovative approaches in oncology drug development include anti-angiogenic strategies, in the form of monoclonal antibodies and small-molecule kinase inhibitors. In this review we aim to present current concepts and controversies surrounding the role of angiogenesis and anti-angiogenic therapies in MM, alluding to other tumor types in which increasing knowledge may supply avenues for future directions in melanoma research and management. An overview of angiogenesis and its importance in melanoma progression is presented, highlighting the key molecules that represent potential therapeutic targets. The results of using anti-angiogenic strategies in preclinical and clinical trials are discussed and future perspectives for anti-angiogenic therapies in MM are considered.
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Affiliation(s)
- Bristi Basu
- Department of Oncology, Oncology Centre, Addenbrooke's Hospital, Cambridge, UK.
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136
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Helfrich I, Scheffrahn I, Bartling S, Weis J, von Felbert V, Middleton M, Kato M, Ergün S, Augustin HG, Schadendorf D. Resistance to antiangiogenic therapy is directed by vascular phenotype, vessel stabilization, and maturation in malignant melanoma. ACTA ACUST UNITED AC 2010; 207:491-503. [PMID: 20194633 PMCID: PMC2839146 DOI: 10.1084/jem.20091846] [Citation(s) in RCA: 144] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Angiogenesis is not only dependent on endothelial cell invasion and
proliferation, it also requires pericyte coverage of vascular sprouts for
stabilization of vascular walls. Clinical efficacy of angiogenesis inhibitors
targeting the vascular endothelial growth factor (VEGF) signaling pathway is
still limited to date. We hypothesized that the level of vessel maturation is
critically involved in the response to antiangiogenic therapies. To test this
hypothesis, we evaluated the vascular network in spontaneously developing
melanomas of MT/ret transgenic mice after using PTK787/ZK222584
for anti-VEGF therapy but also analyzed human melanoma metastases taken at
clinical relapse in patients undergoing adjuvant treatment using bevacizumab.
Both experimental settings showed that tumor vessels, which are resistant to
anti-VEGF therapy, are characterized by enhanced vessel diameter and
normalization of the vascular bed by coverage of mature pericytes and
immunoreactivity for desmin, NG-2, platelet-derived growth factor receptor
β, and the late-stage maturity marker α smooth muscle actin. Our
findings emphasize that the level of mural cell differentiation and
stabilization of the vascular wall significantly contribute to the response
toward antiangiogenic therapy in melanoma. This study may be useful in paving
the way toward a more rational development of second generation antiangiogenic
combination therapies and in providing, for the first time, a murine model to
study this.
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Affiliation(s)
- Iris Helfrich
- Department of Dermatology, University Hospital Essen, Essen, Germany.
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Ribatti D, Annese T, Longo V. Angiogenesis and melanoma. Cancers (Basel) 2010; 2:114-32. [PMID: 24281035 PMCID: PMC3827594 DOI: 10.3390/cancers2010114] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Revised: 02/10/2010] [Accepted: 02/24/2010] [Indexed: 11/16/2022] Open
Abstract
Angiogenesis occurs in pathological conditions, such as tumors, where a specific critical point in tumor progression is the transition from the avascular to the vascular phase. Tumor angiogenesis depends mainly on the release by neoplastic cells of growth factors specific for endothelial cells, which are able to stimulate the growth of the host's blood vessels. This article summarizes the literature concerning the relationship between angiogenesis and human melanoma progression. The recent applications of antiangiogenic agents which interfere with melanoma progression are also described.
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Affiliation(s)
- Domenico Ribatti
- Department of Human Anatomy and Histology, University of Bari Medical School, Piazza G. Cesare, 11, Policlinico 70124, Bari, Italy.
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138
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Hamilton HK, Rose AE, Christos PJ, Shapiro RL, Berman RS, Mazumdar M, Ma MW, Krich D, Liebes L, Brooks PC, Osman I. Increased shedding of HU177 correlates with worse prognosis in primary melanoma. J Transl Med 2010; 8:19. [PMID: 20178639 PMCID: PMC2837640 DOI: 10.1186/1479-5876-8-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Accepted: 02/23/2010] [Indexed: 01/07/2023] Open
Abstract
Background Increased levels of cryptic collagen epitope HU177 in the sera of melanoma patients have been shown to be associated with thicker primary melanomas and with the nodular histologic subtype. In this study, we investigate the association between HU177 shedding in the sera and clinical outcome in terms of disease-free survival (DFS) and overall survival (OS). Methods Serum samples from 209 patients with primary melanoma prospectively enrolled in the Interdisciplinary Melanoma Cooperative Group at the New York University Langone Medical Center (mean age = 58, mean thickness = 2.09 mm, stage I = 136, stage II = 41, stage III = 32, median follow-up = 54.9 months) were analyzed for HU177 concentration using a validated ELISA assay. HU177 serum levels at the time of diagnosis were used to divide the study cohort into two groups: low and high HU177. DFS and OS were estimated by Kaplan-Meier survival analysis, and the log-rank test was used to compare DFS and OS between the two HU177 groups. Multivariate Cox proportional hazards regression models were employed to examine the independent effect of HU177 category on DFS and OS. Results HU177 sera concentrations ranged from 0-139.8 ng/ml (mean and median of 6.2 ng/ml and 3.7 ng/ml, respectively). Thirty-eight of the 209 (18%) patients developed recurrences, and 34 of the 209 (16%) patients died during follow-up. Higher HU177 serum level was associated with an increased rate of melanoma recurrence (p = 0.04) and with increasing mortality (p = 0.01). The association with overall survival remained statistically significant after controlling for thickness and histologic subtype in a multivariate model (p = 0.035). Conclusions Increased shedding of HU177 in the serum of primary melanoma patients is associated with poor prognosis. Further studies are warranted to determine the clinical utility of HU177 in risk stratification compared to the current standard of care.
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Affiliation(s)
- Heather K Hamilton
- Department of Dermatology, New York University School of Medicine, New York, NY, USA
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139
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Geusens B, Sanders N, Prow T, Van Gele M, Lambert J. Cutaneous short-interfering RNA therapy. Expert Opin Drug Deliv 2010; 6:1333-49. [PMID: 19941411 DOI: 10.1517/17425240903304032] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Since the 1990s, RNA interference (RNAi) has become a major subject of interest, not only as a tool for biological research, but also, more importantly, as a therapeutic approach for gene-related diseases. The use of short-interfering RNAs (siRNAs) for the sequence-specific knockdown of disease-causing genes has led to numerous preclinical and even a few clinical studies. Applications for cutaneous delivery of therapeutic siRNA are now emerging owing to a strong demand for effective treatments of various cutaneous disorders. Although successful studies have been performed using several different delivery techniques, most of these techniques encounter limitations for translation to the clinic with regards to patient compliance. This review describes the principal findings and applications in cutaneous RNAi therapy and focuses on the promises and pitfalls of the delivery systems.
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Affiliation(s)
- B Geusens
- Ghent University Hospital, Department of Dermatology, De Pintelaan 185, B-9000 Ghent, Belgium.
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140
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Angiopoietin-1 reduces H(2)O(2)-induced increases in reactive oxygen species and oxidative damage to skin cells. J Invest Dermatol 2010; 130:1307-17. [PMID: 20072135 DOI: 10.1038/jid.2009.431] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
UV light-based damage to skin cells can cause photoaging and skin cancer. A major cause of UV light-induced damage to skin is increased free radicals, such as superoxides. Increased superoxides can cause oxidative and nitrative damage to cell components. Thus, agents that counteract these damages may have therapeutic value. Herein, we show that angiopoietin-1 (ang1) prevented and blocked H(2)O(2)-induced increases in superoxides in human spontaneously immortalized keratinocyte line, HaCaT, and primary melanocytes (HeMn). Ang1 prevented H(2)O(2)-induced increases in damage to DNA (8-hydroxy-2'-deoxyguanosine) and proteins (nitrotyrosinylation). Ang1 promoted skin cell metabolism/viability, adhesion, and akt and MAPK(p42/44) activations. Using multi-gene transcriptional profiling, we found that skin cells express integrin subunits {(beta(1), beta(4-6), beta(8), alpha(v), alpha(2), alpha(3), alpha(6) (HaCaT)), (beta(1), beta(3), beta(5), beta(8), alpha(v), alpha(3) (HeMn))} and lack tie2 receptor mRNA. Integrin antibodies (alpha(v), beta(1)) disrupted skin cell adhesion to ang1 and ang1-induced decreases in superoxides. Our findings show that ang1 blocks free radical damage to skin cells and may be clinically useful to prevent and/or reduce photoaging and skin cancer.
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141
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Detjen KM, Rieke S, Deters A, Schulz P, Rexin A, Vollmer S, Hauff P, Wiedenmann B, Pavel M, Scholz A. Angiopoietin-2 promotes disease progression of neuroendocrine tumors. Clin Cancer Res 2010; 16:420-9. [PMID: 20068079 DOI: 10.1158/1078-0432.ccr-09-1924] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
PURPOSE Inhibition of angiogenesis represents a promising therapeutic strategy in neuroendocrine tumors. Angiopoietin-2 (Ang-2), a ligand of the endothelial tyrosine kinase Tie-2, is emerging as a key regulator of vascular remodeling during tumor angiogenesis. We therefore addressed the expression and biological significance of Ang-2 in human neuroendocrine tumors. EXPERIMENTAL DESIGN Surgical specimens and serum from neuroendocrine tumor patients were used to determine Ang-2 expression by in situ hybridization or ELISA (circulating Ang-2). Ang-2 biological effects were evaluated following stable transfection into BON human pancreatic neuroendocrine tumor cells. BON clones were grown as orthotopic xenografts in nude mice to determine tumor growth and abdominal metastatic spread. Further analyses included microvessel density, lymphatic vessel density, and nodal invasion. RESULTS Specimens from pancreatic neuroendocrine tumors and nontransformed pancreatic tissue revealed uniform expression of Ang-2 mRNA in endothelial cells. In contrast, epithelial expression of Ang-2 mRNA occurred exclusively in neuroendocrine tumors. Overexpression of Ang-2 in BON orthotopic xenografts did not affect primary tumor growth, although successful Ang-2 induction was confirmed from elevated serum levels. However, increased microvessel density and enhanced lymphatic metastasis were evident in Ang-2-expressing tumors, indicating a functional role of Ang-2 in experimental neuroendocrine tumors. Consistent with this notion, circulating Ang-2 was significantly elevated in neuroendocrine tumor patients compared with healthy controls. Circulating Ang-2 furthermore correlated with metastatic versus localized disease. The highest Ang-2 concentrations occurred in patients with liver metastasis, and concentrations >or=75th percentile predicted shorter survival (P = 0.0003). CONCLUSION Induction of Ang-2 in neuroendocrine tumors represents a clinically relevant pathomechanism of disease progression and constitutes an adverse prognostic marker.
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Affiliation(s)
- Katharina M Detjen
- Medizinische Klinik m. S. Hepatologie und Gastroenterologie, Campus Virchow-Klinikum, Charité-Universitätsmedizin, Berlin, Germany.
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De Bock K, De Smet F, Leite De Oliveira R, Anthonis K, Carmeliet P. Endothelial oxygen sensors regulate tumor vessel abnormalization by instructing phalanx endothelial cells. J Mol Med (Berl) 2009; 87:561-9. [PMID: 19455291 DOI: 10.1007/s00109-009-0482-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Revised: 04/23/2009] [Accepted: 04/23/2009] [Indexed: 01/07/2023]
Abstract
An ancestral function of vessels is to conduct blood flow and supply oxygen (O(2)). In hypoxia, cells secrete angiogenic factors to initiate vessel sprouting. Angiogenic factors are balanced off by inhibitors, ensuring that vessels form optimally and supply sufficient oxygen (O(2)). By contrast, in tumors, excessive production of angiogenic factors induces vessels and their endothelial cell (EC) layer to become highly abnormal, thereby impairing tumor perfusion and oxygenation. In such pathological conditions, angiogenic factors act as "abnormalization factors" and promote the vessel "abnormalization switch." Recent genetic data indicate that ECs sense an imbalance in oxygen levels, by using the oxygen-sensing prolyl hydroxylase PHD2. In conditions of O(2) shortage, a decrease in PHD2 activity in ECs initiates a feedback that restores their shape, not their numbers. This induces ECs to align in a streamlined "phalanx" of tightly apposed, regularly ordered cobblestone ECs, which improves perfusion and oxygenation. As a result, EC normalization in PHD2 haplodeficient tumor vessels improves oxygenation and renders tumor cells less invasive and metastatic. This review discusses the role of PHD2 in the regulation of vessel (ab)normalization and the therapeutic potential of PHD2 inhibition for tumor invasiveness and metastasis.
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143
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Thomas M, Augustin HG. The role of the Angiopoietins in vascular morphogenesis. Angiogenesis 2009; 12:125-37. [PMID: 19449109 DOI: 10.1007/s10456-009-9147-3] [Citation(s) in RCA: 278] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Accepted: 04/24/2009] [Indexed: 01/20/2023]
Abstract
The Angiopoietin/Tie system acts as a vascular specific ligand/receptor system to control endothelial cell survival and vascular maturation. The Angiopoietin family includes four ligands (Angiopoietin-1, Angiopoietin-2 and Angiopoietin-3/4) and two corresponding tyrosine kinase receptors (Tie1 and Tie2). Ang-1 and Ang-2 are specific ligands of Tie2 binding the receptor with similar affinity. Tie2 activation promotes vessel assembly and maturation by mediating survival signals for endothelial cells and regulating the recruitment of mural cells. Ang-1 acts in a paracrine agonistic manner inducing Tie2 phosphorylation and subsequent vessel stabilization. In contrast, Ang-2 is produced by endothelial cells and acts as an autocrine antagonist of Ang-1-mediated Tie2 activation. Ang-2 thereby primes the vascular endothelium to exogenous cytokines and induces vascular destabilization at higher concentrations. Ang-2 is strongly expressed in the vasculature of many tumors and it has been suggested that Ang-2 may act synergistically with other cytokines such as vascular endothelial growth factor to promote tumor-associated angiogenesis and tumor progression. The better mechanistic understanding of the Ang/Tie system is gradually paving the way toward the rationale exploitation of this vascular signaling system as a therapeutic target for neoplastic and non-neoplastic diseases.
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Affiliation(s)
- Markus Thomas
- Joint Research Division Vascular Biology, Medical Faculty Mannheim (CBTM), University of Heidelberg, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
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