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Oltean S, Bates DO. Hallmarks of alternative splicing in cancer. Oncogene 2013; 33:5311-8. [PMID: 24336324 DOI: 10.1038/onc.2013.533] [Citation(s) in RCA: 451] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Revised: 11/04/2013] [Accepted: 11/04/2013] [Indexed: 12/17/2022]
Abstract
The immense majority of genes are alternatively spliced and there are many isoforms specifically associated with cancer progression and metastasis. The splicing pattern of specific isoforms of numerous genes is altered as cells move through the oncogenic process of gaining proliferative capacity, acquiring angiogenic, invasive, antiapoptotic and survival properties, becoming free from growth factor dependence and growth suppression, altering their metabolism to cope with hypoxia, enabling them to acquire mechanisms of immune escape, and as they move through the epithelial-mesenchymal and mesenchymal-epithelial transitions and metastasis. Each of the 'hallmarks of cancer' is associated with a switch in splicing, towards a more aggressive invasive cancer phenotype. The choice of isoforms is regulated by several factors (signaling molecules, kinases, splicing factors) currently being identified systematically by a number of high-throughput, independent and unbiased methodologies. Splicing factors are de-regulated in cancer, and in some cases are themselves oncogenes or pseudo-oncogenes and can contribute to positive feedback loops driving cancer progression. Tumour progression may therefore be associated with a coordinated splicing control, meaning that there is the potential for a relatively small number of splice factors or their regulators to drive multiple oncogenic processes. The understanding of how splicing contributes to the various phenotypic traits acquired by tumours as they progress and metastasise, and in particular how alternative splicing is coordinated, can and is leading to the development of a new class of anticancer therapeutics-the alternative-splicing inhibitors.
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Affiliation(s)
- S Oltean
- School of Physiology and Pharmacology, University of Bristol, Bristol, UK
| | - D O Bates
- Division of Pre-clinical Oncology, School of Clinical Sciences, University of Nottingham, Queen's Medical Center, Nottingham, UK
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Gammons MV, Fedorov O, Ivison D, Du C, Clark T, Hopkins C, Hagiwara M, Dick AD, Cox R, Harper SJ, Hancox JC, Knapp S, Bates DO. Topical antiangiogenic SRPK1 inhibitors reduce choroidal neovascularization in rodent models of exudative AMD. Invest Ophthalmol Vis Sci 2013; 54:6052-62. [PMID: 23887803 PMCID: PMC3771558 DOI: 10.1167/iovs.13-12422] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 07/18/2013] [Indexed: 12/14/2022] Open
Abstract
PURPOSE Exudative AMD (wet AMD) is treated by monthly injection into the eye of anti-VEGF proteins. VEGF is alternatively spliced to produce numerous isoforms that differ in angiogenic activity. Serine-rich protein kinase-1 (SRPK1) has been identified as a regulator of pro-angiogenic VEGF splicing by phosphorylating serine-rich splicing factor-1 (SRSF1), which binds to VEGF pre-mRNA. We tested the hypothesis that topical (eye drop) SRPK1-selective inhibitors could be generated that reduce pro-angiogenic isoforms, and prevent choroidal neovascularization in vivo. METHODS Novel inhibitors were tested for SRPK inhibition in vitro, pro-angiogenic VEGF production in RPE cells by PCR and ELISA, and for inhibition of choroidal neovascularisation in mice and rats. RESULTS A novel disubstituted furan inhibitor was selective for the SRPK family of kinases and reduced expression of pro-angiogenic but not antiangiogenic VEGF isoforms. This inhibitor and previously identified SRPK inhibitors significantly reduced choroidal neovascularisation in vivo. Topical administration of SRPK inhibitors dose-dependently blocked CNV with an EC50 of 9 μM. CONCLUSIONS These results indicate that novel SRPK1 selective inhibitors could be a potentially novel topical (eye drop) therapeutic for wet AMD.
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Affiliation(s)
- Melissa V. Gammons
- Microvascular Research Laboratories, School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - Oleg Fedorov
- Nuffield Department of Clinical Medicine, Structural Genomics Consortium and Target Discovery Institute (TDI), University of Oxford, Oxford, United Kingdom
| | - David Ivison
- School of Chemistry, University of Bristol, Bristol, United Kingdom
| | - Chunyun Du
- Cardiovascular Research Laboratories, School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - Tamsyn Clark
- Microvascular Research Laboratories, School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - Claire Hopkins
- Microvascular Research Laboratories, School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - Masatoshi Hagiwara
- Department of Anatomy and Developmental Biology Graduate School of Medicine, Kyoto University, Japan
| | - Andrew D. Dick
- School of Clinical Sciences and School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom
| | - Russell Cox
- School of Chemistry, University of Bristol, Bristol, United Kingdom
| | - Steven J. Harper
- Microvascular Research Laboratories, School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - Jules C. Hancox
- Cardiovascular Research Laboratories, School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - Stefan Knapp
- Nuffield Department of Clinical Medicine, Structural Genomics Consortium and Target Discovery Institute (TDI), University of Oxford, Oxford, United Kingdom
| | - David O. Bates
- Microvascular Research Laboratories, School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
- Cancer Biology, Division of Oncology, School of Medicine, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
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Gammons MVR, Dick AD, Harper SJ, Bates DO. SRPK1 inhibition modulates VEGF splicing to reduce pathological neovascularization in a rat model of retinopathy of prematurity. Invest Ophthalmol Vis Sci 2013; 54:5797-806. [PMID: 23761094 DOI: 10.1167/iovs.13-11634] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE We tested the hypothesis that recombinant human VEGF-A165b and the serine arginine protein kinase (SRPK) inhibitor, SRPIN340, which controls splicing of the VEGF-A pre-mRNA, prevent neovascularization in a rodent model of retinopathy of prematurity (ROP). METHODS In the 50/10 oxygen-induced retinopathy (50/10 OIR) model that exposes newborn rats to repeated cycles of 24 hours of 50% oxygen alternating with 24 hours of 10% oxygen, pups received intraocular injections of SRPIN340, vehicle, VEGF165b, anti-VEGF antibody, or saline. Whole mounts of retinas were prepared for isolectin immunohistochemistry, and preretinal or intravitreal neovascularization (PRNV) determined by clock hour analysis. RESULTS The anti-VEGF antibody (P < 0.04), rhVEGF165b (P < 0.001), and SRPIN340 (P < 0.05) significantly reduced PRNV compared with control eyes. SRPIN340 reduced the expression of proangiogenic VEGF165 without affecting VEGF165b expression. CONCLUSIONS These results suggest that splicing regulation through selective downregulation of proangiogenic VEGF isoforms (via SRPK1 inhibition) or competitive inhibition of VEGF signaling by rhVEGF165b has the potential to be an effective alternative to potential cyto- and neurotoxic anti-VEGF agents in the treatment of pathological neovascularization in the eye.
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Affiliation(s)
- Melissa V R Gammons
- Microvascular Research Laboratories, School of Physiology and Pharmacology, University of Bristol, Bristol, UK
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Bates DO, Mavrou A, Qiu Y, Carter JG, Hamdollah-Zadeh M, Barratt S, Gammons MV, Millar AB, Salmon AHJ, Oltean S, Harper SJ. Detection of VEGF-A(xxx)b isoforms in human tissues. PLoS One 2013; 8:e68399. [PMID: 23935865 PMCID: PMC3729684 DOI: 10.1371/journal.pone.0068399] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Accepted: 05/30/2013] [Indexed: 12/24/2022] Open
Abstract
Vascular Endothelial Growth Factor-A (VEGF-A) can be generated as multiple isoforms by alternative splicing. Two families of isoforms have been described in humans, pro-angiogenic isoforms typified by VEGF-A165a, and anti-angiogenic isoforms typified by VEGF-A165b. The practical determination of expression levels of alternative isoforms of the same gene may be complicated by experimental protocols that favour one isoform over another, and the use of specific positive and negative controls is essential for the interpretation of findings on expression of the isoforms. Here we address some of the difficulties in experimental design when investigating alternative splicing of VEGF isoforms, and discuss the use of appropriate control paradigms. We demonstrate why use of specific control experiments can prevent assumptions that VEGF-A165b is not present, when in fact it is. We reiterate, and confirm previously published experimental design protocols that demonstrate the importance of using positive controls. These include using known target sequences to show that the experimental conditions are suitable for PCR amplification of VEGF-A165b mRNA for both q-PCR and RT-PCR and to ensure that mispriming does not occur. We also provide evidence that demonstrates that detection of VEGF-A165b protein in mice needs to be tightly controlled to prevent detection of mouse IgG by a secondary antibody. We also show that human VEGF165b protein can be immunoprecipitated from cultured human cells and that immunoprecipitating VEGF-A results in protein that is detected by VEGF-A165b antibody. These findings support the conclusion that more information on the biology of VEGF-A165b isoforms is required, and confirm the importance of the experimental design in such investigations, including the use of specific positive and negative controls.
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Affiliation(s)
- David O Bates
- Microvascular Research Laboratories, School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom.
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Arcondéguy T, Lacazette E, Millevoi S, Prats H, Touriol C. VEGF-A mRNA processing, stability and translation: a paradigm for intricate regulation of gene expression at the post-transcriptional level. Nucleic Acids Res 2013; 41:7997-8010. [PMID: 23851566 PMCID: PMC3783158 DOI: 10.1093/nar/gkt539] [Citation(s) in RCA: 166] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Vascular Endothelial Growth Factor A (VEGF-A) is a potent secreted mitogen crucial for physiological and pathological angiogenesis. Post-transcriptional regulation of VEGF-A occurs at multiple levels. Firstly, alternative splicing gives rise to different transcript variants encoding diverse isoforms that exhibit distinct biological properties with regard to receptor binding and extra-cellular localization. Secondly, VEGF-A mRNA stability is regulated by effectors such as hypoxia or growth factors through the binding of stabilizing and destabilizing proteins at AU-rich elements located in the 3′-untranslated region. Thirdly, translation of VEGF-A mRNA is a controlled process involving alternative initiation codons, internal ribosome entry sites (IRESs), an upstream open reading frame (uORF), miRNA targeting and a riboswitch in the 3′ untranslated region. These different levels of regulation cooperate for the crucial fine-tuning of the expression of VEGF-A variants. This review will be focused on our current knowledge of the complex post-transcriptional regulatory switches that modulate the cellular VEGF-A level, a paradigmatic model of post-transcriptional regulation.
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Affiliation(s)
- Tania Arcondéguy
- Inserm UMR1037, Centre de Recherches en Cancérologie de Toulouse, CHU Rangueil, BP84225, 31432 Toulouse Cedex 4, France and Université Toulouse III Paul-Sabatier, 118 Route de Narbonne, 31400 Toulouse, France
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Beazley-Long N, Hua J, Jehle T, Hulse RP, Dersch R, Lehrling C, Bevan H, Qiu Y, Lagrèze WA, Wynick D, Churchill AJ, Kehoe P, Harper SJ, Bates DO, Donaldson LF. VEGF-A165b is an endogenous neuroprotective splice isoform of vascular endothelial growth factor A in vivo and in vitro. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 183:918-29. [PMID: 23838428 DOI: 10.1016/j.ajpath.2013.05.031] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 05/19/2013] [Accepted: 05/31/2013] [Indexed: 01/13/2023]
Abstract
Vascular endothelial growth factor (VEGF) A is generated as two isoform families by alternative RNA splicing, represented by VEGF-A165a and VEGF-A165b. These isoforms have opposing actions on vascular permeability, angiogenesis, and vasodilatation. The proangiogenic VEGF-A165a isoform is neuroprotective in hippocampal, dorsal root ganglia, and retinal neurons, but its propermeability, vasodilatatory, and angiogenic properties limit its therapeutic usefulness. In contrast, a neuroprotective effect of endogenous VEGF-A165b on neurons would be advantageous for neurodegenerative pathologies. Endogenous expression of human and rat VEGF-A165b was detected in hippocampal and cortical neurons. VEGF-A165b formed a significant proportion of total VEGF-A in rat brain. Recombinant human VEGF-A165b exerted neuroprotective effects in response to multiple insults, including glutamatergic excitotoxicity in hippocampal neurons, chemotherapy-induced cytotoxicity of dorsal root ganglion neurons, and retinal ganglion cells (RGCs) in rat retinal ischemia-reperfusion injury in vivo. Neuroprotection was dependent on VEGFR2 and MEK1/2 activation but not on p38 or phosphatidylinositol 3-kinase activation. Recombinant human VEGF-A165b is a neuroprotective agent that effectively protects both peripheral and central neurons in vivo and in vitro through VEGFR2, MEK1/2, and inhibition of caspase-3 induction. VEGF-A165b may be therapeutically useful for pathologies that involve neuronal damage, including hippocampal neurodegeneration, glaucoma diabetic retinopathy, and peripheral neuropathy. The endogenous nature of VEGF-A165b expression suggests that non-isoform-specific inhibition of VEGF-A (for antiangiogenic reasons) may be damaging to retinal and sensory neurons.
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Affiliation(s)
- Nicholas Beazley-Long
- Microvascular Research Laboratories, School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
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Bradshaw M, Mansfield A, Peikert T. The role of vascular endothelial growth factor in the pathogenesis, diagnosis and treatment of malignant pleural effusion. Curr Oncol Rep 2013; 15:207-16. [PMID: 23568600 PMCID: PMC3674487 DOI: 10.1007/s11912-013-0315-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Malignant pleural effusions (MPEs) are a significant source of cancer-related morbidity. Over 150,000 patients in the United States suffer from breathlessness and diminished quality of life due to MPE each year. Current management strategies are of mostly palliative value and focus on symptom control; they do not address the pathobiology of the effusion, nor do they improve survival. Further elucidation of the pathophysiological mechanisms, coupled with the development of novel treatments such as intrapleural chemotherapeutics targeting this process, has the potential to greatly improve the efficacy of our current management options. Vascular endothelial growth factor-A (VEGF-A) has been implicated as a critical cytokine in the formation of malignant pleural effusions. Elevated levels of VEGF produced by tumor cells, mesothelial cells, and infiltrating immune cells result in increased vascular permeability, cancer cell transmigration, and angiogenesis. Therefore antiangiogenic therapies such as Bevacizumab, a monoclonal antibody targeting VEGF-A, may have a potential role in the management of malignant pleural effusions. Herein we review the pathogenesis and potential treatment strategies of malignant pleural effusions, with a focus on angiogenesis and antiangiogenic therapeutics.
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Pasquali S, van der Ploeg APT, Mocellin S, Stretch JR, Thompson JF, Scolyer RA. Lymphatic biomarkers in primary melanomas as predictors of regional lymph node metastasis and patient outcomes. Pigment Cell Melanoma Res 2013; 26:326-37. [PMID: 23298266 DOI: 10.1111/pcmr.12064] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 01/02/2013] [Indexed: 11/26/2022]
Abstract
Recently developed lymphatic-specific immunohistochemical markers can now be utilized to assess intratumoral and/or peritumoral lymphatic vessel density (LVD), to detect lymphatic vessel invasion (LVI) by melanoma cells and to identify lymphatic marker expression in melanoma cells themselves. We systematically reviewed the available evidence for the expression of lymphatic markers as predictors of regional node metastasis and survival in melanoma patients. The currently available evidence suggests that LVD (particularly in a peritumoral location) and LVI are predictors of sentinel node metastasis and poorer survival. Nevertheless, adherence to international guidelines in the conduct and reporting of the studies was generally poor, with wide methodologic variations and heterogeneous findings. Larger, carefully conducted and well-reported studies that confirm these preliminary findings are required before it would be appropriate to recommend the routine application of costly and time-consuming immunohistochemistry for lymphatic markers in the routine clinical assessment of primary cutaneous melanomas.
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Affiliation(s)
- Sandro Pasquali
- Melanoma Institute Australia, The University of Sydney, Sydney, NSW, Australia.
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Shibuya M. Vascular endothelial growth factor and its receptor system: physiological functions in angiogenesis and pathological roles in various diseases. J Biochem 2012; 153:13-9. [PMID: 23172303 DOI: 10.1093/jb/mvs136] [Citation(s) in RCA: 525] [Impact Index Per Article: 43.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Vascular endothelial growth factors (VEGFs) belong to the platelet-derived growth factor supergene family, and they play central roles in the regulation of angiogenesis and lymphangiogenesis. VEGF-A, the major factor for angiogenesis, binds to two tyrosine kinase (TK) receptors, VEGFR-1 (Flt-1) and VEGFR-2 (KDR/Flk-1), and regulates endothelial cell proliferation, migration, vascular permeability, secretion and other endothelial functions. VEGFR-2 exhibits a strong TK activity towards pro-angiogenic signals, whereas the soluble VEGFR-1 (sFlt-1) functions as an endogenous VEGF inhibitor. sFlt-1 is abnormally overexpressed in the placenta of preeclampsia patients, resulting in the major symptoms of the disease due to abnormal trapping of VEGFs. The VEGF-VEGFR system is crucial for tumour angiogenesis, and anti-VEGF-VEGFR molecules are now widely used in the clinical field to treat cancer patients. The efficacy of these molecules in prolonging the overall survival of patients has been established; however, some cancers do not respond well and reduced tumour sensitivity to anti-VEGF signals may occur after long-term treatment. The molecular basis of tumour refractoriness should be determined to improve anti-angiogenic therapy.
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Affiliation(s)
- Masabumi Shibuya
- Gakubunkan Institute of Physiology and Medicine, Jobu University, 270-1 Shinmachi, Takasaki, Gunma 370-1393, Japan.
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Bates DO, Catalano PJ, Symonds KE, Varey AHR, Ramani P, O'Dwyer PJ, Giantonio BJ, Meropol NJ, Benson AB, Harper SJ. Association between VEGF splice isoforms and progression-free survival in metastatic colorectal cancer patients treated with bevacizumab. Clin Cancer Res 2012; 18:6384-91. [PMID: 23104894 DOI: 10.1158/1078-0432.ccr-12-2223] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Bevacizumab improves survival for patients with metastatic colorectal cancer with chemotherapy, but no proven predictive markers exist. The VEGF-A splice form, VEGF(165)b, anti-angiogenic in animal models, binds bevacizumab. We tested the hypothesis that prolonged progression-free survival (PFS) would occur only in patients with low relative VEGF(165)b levels treated with bevacizumab. EXPERIMENTAL DESIGN Blinded tumor samples from the phase III trial of FOLFOX4 ± bevacizumab were assessed for VEGF(165)b and VEGF(total) by immunohistochemistry and scored relative to normal tissue. A predictive index (PI) was derived from the ratio of VEGF(165)b:VEGF(total) for 44 samples from patients treated with FOLFOX + bevacizumab (arm A) and 53 samples from patients treated with FOLFOX4 (arm B), and PFS, and overall survival (OS) analyzed on the basis of PI relative to median ratio. RESULTS Unadjusted analysis of PFS showed significantly better outcome for individuals with VEGF(165)b:VEGF(total) ratio scores below median treated with FOLFOX4 + bevacizumab compared with FOLFOX4 alone (median, 8.0 vs. 5.2 months; P < 0.02), but no effect of bevacizumab on PFS in patients with VEGF(165)b:VEGF(total) ratio >median (5.9 vs. 6.3 months). These findings held after adjustment for other clinical and demographic features. OS was increased in arm A (median, 13.6 months) compared with arm B (10.6 months) in the low VEGF(165)b group, but this did not reach statistical significance. There was no difference in the high VEGF(165)b:VEGF(total) group between FOLFOX + bevacizumab (10.8 months) and FOLFOX alone (11.3 months). CONCLUSION Low VEGF(165)b:VEGF(total) ratio may be a predictive marker for bevacizumab in metastatic colorectal cancer, and individuals with high relative levels may not benefit.
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Affiliation(s)
- David O Bates
- Microvascular Research Laboratories, Department of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom.
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Abstract
Anti-angiogenic vascular endothelial growth factor A (VEGF) 165b and pro-angiogenic VEGF 165 are generated from the same transcript, and their relative amounts are dependent on alternative splicing. The role of VEGF 165b has not been investigated in as much detail as VEGF 165, although it appears to be highly expressed in non-angiogenic tissues and, in contrast with VEGF 165, is downregulated in tumors and other pathologies associated with abnormal neovascularization such as diabetic retinopathy or Denys Drash syndrome. VEGF 165b inhibits VEGFR2 signaling by inducing differential phosphorylation, and it can be used to block angiogenesis in in vivo models of tumorigenesis and angiogenesis-related eye disease. Recent reports have identified three serine/arginine-rich proteins, SRSF1, SRSF2 and SRSF6, and studied their role in regulating terminal splice-site selection. Since the balance of VEGF isoforms is lost in cancer and angiogenesis-related conditions, control of VEGF splicing could also be used as a basis for therapy in these diseases.
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Affiliation(s)
- Maria Peiris-Pagès
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY, USA
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Assessing the in vivo efficacy of biologic antiangiogenic therapies. Cancer Chemother Pharmacol 2012; 71:1-12. [PMID: 23053262 DOI: 10.1007/s00280-012-1978-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Accepted: 09/13/2012] [Indexed: 12/13/2022]
Abstract
PURPOSE To review key clinical issues underlying the assessment of in vivo efficacy when using antiangiogenic therapies for cancer treatment. METHODS Literature relevant to use of antiangiogenic therapies in cancer was reviewed, with particular emphasis on the assessment of in vivo efficacy of these agents, as well as additional angiogenic factors that could play a role in escape from angiogenesis inhibition. RESULTS In order to grow and metastasize, tumors need to continually acquire new blood supplies; therefore, therapeutic inhibition of angiogenesis has become a component of anticancer treatment for many tumor types. Bevacizumab, a humanized monoclonal antibody directed at vascular endothelial growth factor A (VEGF-A), has shown activity in combination with chemotherapy in metastatic colorectal cancer. Nevertheless, the use of antiangiogenic therapies remains suboptimal; specifically, optimal dose, duration of therapy, and combination of agents remain unknown. Also, at present, it is not possible to determine which patients are most likely to respond to a given form of antiangiogenic therapy. There has been increased recognition of alternative pathways possibly associated with disease progression in patients undergoing antiangiogenic therapy targeted at VEGF-A. Multiligand-targeted antiangiogenic therapies, such as ziv-aflibercept (formerly known as aflibercept, VEGF Trap), are currently undergoing clinical evaluation. Ziv-aflibercept forms monomeric complexes with VEGF-A, VEGF-B, and PlGF, which have a long half-life, allowing optimization of ziv-aflibercept doses and angiogenic blockage. CONCLUSIONS Although antiangiogenic therapies have increased treatment options for cancer patients, their use is limited by a lack of established and standardized methodology to evaluate their efficacy in vivo. Circulating endothelial cells, hypertension, and several molecular and imaging-based markers have potential for use as biomarkers in these patients and may better define appropriate patient populations.
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Jewer M, Findlay SD, Postovit LM. Post-transcriptional regulation in cancer progression : Microenvironmental control of alternative splicing and translation. J Cell Commun Signal 2012; 6:233-48. [PMID: 23054595 DOI: 10.1007/s12079-012-0179-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 09/24/2012] [Indexed: 12/28/2022] Open
Abstract
The microenvironment acts as a conduit for cellular communication, delivering signals that direct development and sustain tissue homeostasis. In pathologies such as cancer, this integral function of the microenvironment is hijacked to support tumor growth and progression. Cells sense the microenvironment via signal transduction pathways culminating in altered gene expression. In addition to induced transcriptional changes, the microenvironment exerts its effect on the cell through regulation of post-transcriptional processes including alternative splicing and translational control. Here we describe how alternative splicing and protein translation are controlled by microenvironmental parameters such as oxygen availability. We also emphasize how these pathways can be utilized to support processes that are hallmarks of cancer such as angiogenesis, proliferation, and cell migration. We stress that cancer cells respond to their microenvironment through an integrated regulation of gene expression at multiple levels that collectively contribute to disease progression.
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Affiliation(s)
- Michael Jewer
- Department of Anatomy & Cell Biology, The Schulich School of Medicine and Dentistry, Western University, 438 Medical Science Building, London, ON, N6A 5C1, Canada
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Seguin F, Carvalho MA, Bastos DC, Agostini M, Zecchin KG, Alvarez-Flores MP, Chudzinski-Tavassi AM, Coletta RD, Graner E. The fatty acid synthase inhibitor orlistat reduces experimental metastases and angiogenesis in B16-F10 melanomas. Br J Cancer 2012; 107:977-87. [PMID: 22892389 PMCID: PMC3464771 DOI: 10.1038/bjc.2012.355] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 07/12/2012] [Accepted: 07/17/2012] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Fatty acid synthase (FASN) is overexpressed and associated with poor prognosis in several human cancers. Here, we investigate the effect of FASN inhibitors on the metastatic spread and angiogenesis in experimental melanomas and cultured melanoma cells. METHODS The lung colonisation assay and cutaneous melanomas were performed by the inoculation of mouse melanoma B16-F10 cells in C57BL6 mice. Blood vessel endothelial cells (RAEC and HUVEC) were applied to determine cell proliferation, apoptosis, and the formation of capillary-like structures. Vascular endothelial growth factor A (VEGFA) expression was evaluated by quantitative RT-PCR and ELISA in B16-F10, human melanoma (SK-MEL-25), and human oral squamous carcinoma (SCC-9) cells. Conditioned media from these cancer cell lines were used to study the effects of FASN inhibitors on endothelial cells. RESULTS B16-F10 melanoma-induced metastases and angiogenesis were significantly reduced in orlistat-treated mice. Fatty acid synthase inhibitors reduced the viability, proliferation, and the formation of capillary-like structures by RAEC cells, as well as the tumour cell-mediated formation of HUVEC capillary-like structures. Cerulenin and orlistat stimulated the production of total VEGFA in B16-F10, SK-MEL-25, and SCC-9 cells. Both drugs also enhanced VEGFA(121), (165), (189,) and (165b) in SK-MEL-25 and SCC-9 cells. CONCLUSION FASN inhibitors reduce metastasis and tumour-induced angiogenesis in experimental melanomas, and differentially modulate VEGFA expression in B16-F10 cells.
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Affiliation(s)
- F Seguin
- Department of Oral Diagnosis, School of Dentistry of Piracicaba, University of Campinas (UNICAMP), Avenida Limeira 901, CP 52, Areão, Piracicaba, CEP 13414-018, SP, Brazil
| | - M A Carvalho
- Department of Oral Diagnosis, School of Dentistry of Piracicaba, University of Campinas (UNICAMP), Avenida Limeira 901, CP 52, Areão, Piracicaba, CEP 13414-018, SP, Brazil
| | - D C Bastos
- Department of Oral Diagnosis, School of Dentistry of Piracicaba, University of Campinas (UNICAMP), Avenida Limeira 901, CP 52, Areão, Piracicaba, CEP 13414-018, SP, Brazil
| | - M Agostini
- Department of Oral Diagnosis, School of Dentistry of Piracicaba, University of Campinas (UNICAMP), Avenida Limeira 901, CP 52, Areão, Piracicaba, CEP 13414-018, SP, Brazil
| | - K G Zecchin
- Department of Oral Diagnosis, School of Dentistry of Piracicaba, University of Campinas (UNICAMP), Avenida Limeira 901, CP 52, Areão, Piracicaba, CEP 13414-018, SP, Brazil
| | - M P Alvarez-Flores
- Laboratory of Biochemistry and Biophysics, Butantan Institute, Avenida Vital Brasil 1500, Butantã, São Paulo, CEP 05503-900, SP, Brazil
| | - A M Chudzinski-Tavassi
- Laboratory of Biochemistry and Biophysics, Butantan Institute, Avenida Vital Brasil 1500, Butantã, São Paulo, CEP 05503-900, SP, Brazil
| | - R D Coletta
- Department of Oral Diagnosis, School of Dentistry of Piracicaba, University of Campinas (UNICAMP), Avenida Limeira 901, CP 52, Areão, Piracicaba, CEP 13414-018, SP, Brazil
| | - E Graner
- Department of Oral Diagnosis, School of Dentistry of Piracicaba, University of Campinas (UNICAMP), Avenida Limeira 901, CP 52, Areão, Piracicaba, CEP 13414-018, SP, Brazil
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Shibuya M. Vascular Endothelial Growth Factor (VEGF) and Its Receptor (VEGFR) Signaling in Angiogenesis: A Crucial Target for Anti- and Pro-Angiogenic Therapies. Genes Cancer 2012; 2:1097-105. [PMID: 22866201 DOI: 10.1177/1947601911423031] [Citation(s) in RCA: 953] [Impact Index Per Article: 79.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The vascular endothelial growth factor (VEGF) and its receptor (VEGFR) have been shown to play major roles not only in physiological but also in most pathological angiogenesis, such as cancer. VEGF belongs to the PDGF supergene family characterized by 8 conserved cysteines and functions as a homodimer structure. VEGF-A regulates angiogenesis and vascular permeability by activating 2 receptors, VEGFR-1 (Flt-1) and VEGFR-2 (KDR/Flk1 in mice). On the other hand, VEGF-C/VEGF-D and their receptor, VEGFR-3 (Flt-4), mainly regulate lymphangiogenesis. The VEGF family includes other interesting variants, one of which is the virally encoded VEGF-E and another is specifically expressed in the venom of the habu snake (Trimeresurus flavoviridis). VEGFRs are distantly related to the PDGFR family; however, they are unique with respect to their structure and signaling system. Unlike members of the PDGFR family that strongly stimulate the PI3K-Akt pathway toward cell proliferation, VEGFR-2, the major signal transducer for angiogenesis, preferentially utilizes the PLCγ-PKC-MAPK pathway for signaling. The VEGF-VEGFR system is an important target for anti-angiogenic therapy in cancer and is also an attractive system for pro-angiogenic therapy in the treatment of neuronal degeneration and ischemic diseases.
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66
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Alternative transcription and alternative splicing in cancer. Pharmacol Ther 2012; 136:283-94. [PMID: 22909788 DOI: 10.1016/j.pharmthera.2012.08.005] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 08/01/2012] [Indexed: 01/27/2023]
Abstract
In recent years, the notion of "one gene makes one protein that functions in one signaling pathway" in mammalian cells has been shown to be overly simplistic. Recent genome-wide studies suggest that at least half of the human genes, including many therapeutic target genes, produce multiple protein isoforms through alternative splicing and alternative usage of transcription initiation and/or termination. For example, alternative splicing of the vascular endothelial growth factor gene (VEGFA) produces multiple protein isoforms, which display either pro-angiogenic or anti-angiogenic activities. Similarly, for the majority of human genes, the inclusion or exclusion of exonic sequences enhances the generation of transcript variants and/or protein isoforms that can vary in structure and functional properties. Many of the isoforms produced in this manner are tightly regulated during normal development but are misregulated in cancer cells. Altered expression of transcript variants and protein isoforms for numerous genes is linked with disease and its prognosis, and cancer cells manipulate regulatory mechanisms to express specific isoforms that confer drug resistance and survival advantages. Emerging insights indicate that modulating the expression of transcript and protein isoforms of a gene may hold the key to impeding tumor growth and act as a model for efficient targeting of disease-associated genes at the isoform level. This review highlights the role and regulation of alternative transcription and splicing mechanisms in generating the transcriptome, and the misuse and diagnostic/prognostic potential of alternative transcription and splicing in cancer.
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67
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Kaida D, Schneider-Poetsch T, Yoshida M. Splicing in oncogenesis and tumor suppression. Cancer Sci 2012; 103:1611-6. [PMID: 22691055 DOI: 10.1111/j.1349-7006.2012.02356.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Revised: 06/04/2012] [Accepted: 06/07/2012] [Indexed: 12/23/2022] Open
Abstract
Post-transcriptional modifications, such as 5' end capping, 3' end polyadenylation and splicing, are necessary for the precise regulation of gene expression and transcriptome integrity. Therefore, it is not surprising that abnormalities of these post-transcriptional modifications prompt numerous diseases, including cancer. In fact, many studies revealed that misregulation of mRNA processing, especially splicing, are observed in a variety of cancer cells. In this review we describe how changes within RNA splicing regulatory elements or mutations in the processing factors alter the expression of tumor suppressors or oncogenes with pathological consequences. In addition, we show how several small molecules that bind to spliceosomal components and splicing regulators inhibit or modulate splicing activity. These compounds have anticancer activity and further development of small molecule modulators has potential in next generation cancer therapy.
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Affiliation(s)
- Daisuke Kaida
- Frontier Research Core for Life Sciences, University of Toyama, Japan
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68
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Kim YJ, Kim HS. Alternative splicing and its impact as a cancer diagnostic marker. Genomics Inform 2012; 10:74-80. [PMID: 23105933 PMCID: PMC3480681 DOI: 10.5808/gi.2012.10.2.74] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Revised: 05/18/2012] [Accepted: 05/21/2012] [Indexed: 01/13/2023] Open
Abstract
Most genes are processed by alternative splicing for gene expression, resulting in the complexity of the transcriptome in eukaryotes. It allows a limited number of genes to encode various proteins with intricate functions. Alternative splicing is regulated by genetic mutations in cis-regulatory factors and epigenetic events. Furthermore, splicing events occur differently according to cell type, developmental stage, and various diseases, including cancer. Genome instability and flexible proteomes by alternative splicing could affect cancer cells to grow and survive, leading to metastasis. Cancer cells that are transformed by aberrant and uncontrolled mechanisms could produce alternative splicing to maintain and spread them continuously. Splicing variants in various cancers represent crucial roles for tumorigenesis. Taken together, the identification of alternative spliced variants as biomarkers to distinguish between normal and cancer cells could cast light on tumorigenesis.
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Affiliation(s)
- Yun-Ji Kim
- Department of Biological Sciences, College of Natural Sciences, Pusan National University, Busan 609-735, Korea
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69
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Dewing D, Emmett M, Pritchard Jones R. The Roles of Angiogenesis in Malignant Melanoma: Trends in Basic Science Research over the Last 100 Years. ISRN ONCOLOGY 2012; 2012:546927. [PMID: 22720169 PMCID: PMC3376762 DOI: 10.5402/2012/546927] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Accepted: 04/28/2012] [Indexed: 12/13/2022]
Abstract
Blood vessels arose during evolution carrying oxygen and nutrients to distant organs via complex networks of blood vessels penetrating organs and tissues. Mammalian cells require oxygen and nutrients for survival, of which oxygen has a diffusion limit of 100 to 200 μm between cell and blood vessel. For growth beyond this margin, cells must recruit new blood vessels, first by vasculogenesis, where embryonic vessels form from endothelial precursors, then angiogenesis which is the sprouting of interstitial tissue columns into the lumen of preexisting blood vessels. Angiogenesis occurs in many inflammatory diseases and in many malignant disease states, including over 90% of solid tumours. Malignant melanoma (MM) is the most lethal skin cancer, highly angiogenic, highly metastatic, and refractory to all treatments. Raised serum levels of vascular endothelial growth factor (VEGF) strongly correlate MM disease progression and poor prognosis. Melanoma cells secrete several proangiogenic cytokines including VEGF-A, fibroblast growth factor (FGF-2), platelet growth factor (PGF-1), interleukin-8 (IL-8), and transforming growth factor (TGF-1) that modulate the angiogenic switch, changing expression levels during tumour transition from radial to invasive vertical and then metastatic growth. We highlight modern and historical lines of research and development that are driving this exciting area of research currently.
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Affiliation(s)
- D Dewing
- Department of Molecular and Clinical Cancer Medicine, Mersey Academic Plastic Surgery Group, Liverpool Cancer Research UK Centre, The Duncan Building, Daulby Street, Liverpool L69 3GA, UK
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70
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Do anti-angiogenic VEGF (VEGFxxxb) isoforms exist? A cautionary tale. PLoS One 2012; 7:e35231. [PMID: 22567098 PMCID: PMC3342274 DOI: 10.1371/journal.pone.0035231] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Accepted: 03/14/2012] [Indexed: 12/28/2022] Open
Abstract
Splicing of the human vascular endothelial growth factor-A (VEGF-A) gene has been reported to generate angiogenic (VEGFxxx) and anti-angiogenic (VEGFxxxb) isoforms. Corresponding VEGFxxxb isoforms have also been reported in rat and mouse. We examined VEGFxxxb expression in mouse fibrosarcoma cell lines expressing all or individual VEGF isoforms (VEGF120, 164 or 188), grown in vitro and in vivo, and compared results with those from normal mouse and human tissues. Importantly, genetic construction of VEGF164 and VEGF188 expressing fibrosarcomas, in which exon 7 is fused to the conventional exon 8, precludes VEGFxxxb splicing from occurring. Thus, these two fibrosarcoma cell lines provided endogenous negative controls. Using RT-PCR we show that primers designed to simultaneously amplify VEGFxxx and VEGFxxxb isoforms amplified only VEGFxxx variants in both species. Moreover, only VEGFxxx species were generated when mouse podocytes were treated with TGFβ-1, a reported activator of VEGFxxxb splice selection in human podocytes. A VEGF164/120 heteroduplex species was identified as a PCR artefact, specifically in mouse. VEGFxxxb isoform-specific PCR did amplify putative VEGFxxxb species in mouse and human tissues, but unexpectedly also in VEGF188 and VEGF164 fibrosarcoma cells and tumours, where splicing to produce true VEGFxxxb isoforms cannot occur. Moreover, these products were only consistently generated using reverse primers spanning more than 5 bases across the 8b/7 or 8b/5 splice junctions. Primer annealing to VEGFxxx transcripts and amplification of exon 8b primer ‘tails’ explained the artefactual generation of VEGFxxxb products, since the same products were generated when the PCR reactions were performed with cDNA from VEGF164/VEGF188 ‘knock-in’ vectors used in the generation of single VEGF isoform-expressing transgenic mice from which the fibrosarcoma lines were developed. Collectively, our results highlight important pitfalls in data interpretation associated with detecting VEGFxxxb isoforms using current methods, and demonstrate that anti-angiogenic isoforms are not commonly expressed in mouse or human tissues.
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71
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Qiu Y, Seager M, Osman A, Castle-Miller J, Bevan H, Tortonese DJ, Murphy D, Harper SJ, Fraser HM, Donaldson LF, Bates DO. Ovarian VEGF(165)b expression regulates follicular development, corpus luteum function and fertility. Reproduction 2012; 143:501-11. [PMID: 22232745 PMCID: PMC3325318 DOI: 10.1530/rep-11-0091] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 12/07/2011] [Accepted: 01/09/2012] [Indexed: 12/22/2022]
Abstract
Angiogenesis and vascular regression are critical for the female ovulatory cycle. They enable progression and regression of follicular development, and corpora lutea formation and regression. Angiogenesis in the ovary occurs under the control of the vascular endothelial growth factor-A (VEGFA) family of proteins, which are generated as both pro-(VEGF(165)) and anti(VEGF(165)b)-angiogenic isoforms by alternative splicing. To determine the role of the VEGF(165)b isoforms in the ovulatory cycle, we measured VEGF(165)b expression in marmoset ovaries by immunohistochemistry and ELISA, and used transgenic mice over-expressing VEGF(165)b in the ovary. VEGF(165)b was expressed in the marmoset ovaries in granulosa cells and theca, and the balance of VEGF(165)b:VEGF(165) was regulated during luteogenesis. Mice over-expressing VEGF(165)b in the ovary were less fertile than wild-type littermates, had reduced secondary and tertiary follicles after mating, increased atretic follicles, fewer corpora lutea and generated fewer embryos in the oviduct after mating, and these were more likely not to retain the corona radiata. These results indicate that the balance of VEGFA isoforms controls follicle progression and luteogenesis, and that control of isoform expression may regulate fertility in mammals, including in primates.
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Affiliation(s)
- Y Qiu
- Microvascular Research LaboratoriesSchool of Physiology and Pharmacology, Bristol Heart InstitutePre-clinical Veterinary Sciences Building, Southwell Street, Bristol, BS2 8EJUK
| | - M Seager
- Microvascular Research LaboratoriesSchool of Physiology and Pharmacology, Bristol Heart InstitutePre-clinical Veterinary Sciences Building, Southwell Street, Bristol, BS2 8EJUK
| | - A Osman
- Microvascular Research LaboratoriesSchool of Physiology and Pharmacology, Bristol Heart InstitutePre-clinical Veterinary Sciences Building, Southwell Street, Bristol, BS2 8EJUK
| | - J Castle-Miller
- Microvascular Research LaboratoriesSchool of Physiology and Pharmacology, Bristol Heart InstitutePre-clinical Veterinary Sciences Building, Southwell Street, Bristol, BS2 8EJUK
- Centre for Comparative and Clinical AnatomyUniversity of BristolPre-clinical Veterinary Sciences Building, Southwell Street, Bristol, BS2 8EJUK
| | - H Bevan
- Microvascular Research LaboratoriesSchool of Physiology and Pharmacology, Bristol Heart InstitutePre-clinical Veterinary Sciences Building, Southwell Street, Bristol, BS2 8EJUK
| | - D J Tortonese
- Centre for Comparative and Clinical AnatomyUniversity of BristolPre-clinical Veterinary Sciences Building, Southwell Street, Bristol, BS2 8EJUK
| | - D Murphy
- Henry Wellcome Laboratories for Integrative Neuroscience and EndocrinologyUniversity of BristolBristolUK
| | - S J Harper
- Microvascular Research LaboratoriesSchool of Physiology and Pharmacology, Bristol Heart InstitutePre-clinical Veterinary Sciences Building, Southwell Street, Bristol, BS2 8EJUK
| | - H M Fraser
- MRC Human Reproductive Sciences UnitQueen's Medical Research Institute47 Little France Crescent, Edinburgh, EH16 4TJUK
| | - L F Donaldson
- School of Physiology and PharmacologyMedical Sciences Building, University Walk, Bristol, BS8 1TDUK
| | - D O Bates
- Microvascular Research LaboratoriesSchool of Physiology and Pharmacology, Bristol Heart InstitutePre-clinical Veterinary Sciences Building, Southwell Street, Bristol, BS2 8EJUK
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Development of a multiplexed PCR-coupled liquid bead array assay for vascular endothelial growth factor (VEGF) splice variants. Clin Biochem 2012; 45:475-82. [PMID: 22330939 DOI: 10.1016/j.clinbiochem.2012.01.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Revised: 01/24/2012] [Accepted: 01/26/2012] [Indexed: 12/27/2022]
Abstract
OBJECTIVES To develop a multiplex PCR-coupled liquid bead array assay for the expression of VEGF splice variants. DESIGN AND METHODS The assay was based on the combination of multiplex PCR with liquid bead array technology, and optimized and evaluated in terms of analytical sensitivity, specificity, and reproducibility using the MCF-7 cell line. Clinical performance was evaluated in 16 pairs of fresh frozen cancerous and corresponding noncancerous adjacent tissues from NSCLC patients. RESULTS The assay is highly sensitive, reproducible and can detect specifically VEGF splice variants in clinical samples. When applied in 32 clinical samples it gave comparable results to RT-qPCR (concordance of 81%, 75%, 88% and 81% for PBGD, VEGF(121), VEGF(165), and VEGF(189) respectively). CONCLUSIONS The developed assay can simultaneously detect three VEGF splice variants with high specificity and sensitivity and can be further used to evaluate the role of each individual VEGF splice variant in molecular therapies targeted against VEGF.
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73
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Baba T, McLeod DS, Edwards MM, Merges C, Sen T, Sinha D, Lutty GA. VEGF 165 b in the developing vasculatures of the fetal human eye. Dev Dyn 2012; 241:595-607. [PMID: 22275161 DOI: 10.1002/dvdy.23743] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/03/2012] [Indexed: 12/19/2022] Open
Abstract
VEGF(165) b is an anti-angiogenic form of VEGF(165) produced by alternative splicing. The localization of pro-angiogenic VEGF(165) and anti-angiogenic VEGF(165) b was investigated during development of the vasculatures in fetal human eyes from 7 to 21 weeks gestation (WG). The fetal vasculature of vitreous, which includes tunica vasculosa lentis (TVL), had moderate VEGF(165) immunoreactivity at 7WG and very little VEGF(165) b. Both forms were elevated at 12WG. VEGF(165) then decreased around 17WG when the TVL regresses but VEGF(165) b remained elevated. In choroid, VEGF(165) was present in forming choriocapillaris (CC) and retinal pigment epithelium (RPE) at 7WG while VEGF165b was present in CC and mesenchymal precursors within the choroidal stroma. By 21WG, both forms were elevated in RPE and choroidal blood vessels but VEGF(165) b was apical and VEGF(165) basal in RPE. Diffuse VEGF(165) immunoreactivity was prominent in 12WG innermost retina where blood vessels will form while VEGF(165) b was present in most CXCR4(+) progenitors in the inner neuroblastic layer and migrating angioblasts in the putative nerve fiber layer. By 21WG, VEGF(165) was present in nerve fibers and VEGF(165) b in the inner Muller cell process. The localization of VEGF(165) b was distinctly different from VEGF(165) both spatially and temporally and it was often associated with nucleus in progenitors.
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Affiliation(s)
- Takayuki Baba
- Wilmer Ophthalmological Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA
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74
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Biselli-Chicote PM, Oliveira ARCP, Pavarino EC, Goloni-Bertollo EM. VEGF gene alternative splicing: pro- and anti-angiogenic isoforms in cancer. J Cancer Res Clin Oncol 2011; 138:363-70. [PMID: 22045472 DOI: 10.1007/s00432-011-1073-2] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Accepted: 09/21/2011] [Indexed: 12/28/2022]
Abstract
Tumor growth and progression depend on angiogenesis, a process of new blood vessels formation from a preexisting vascular endothelium. Tumors promote angiogenesis by secreting or activating angiogenic factors that stimulate endothelial proliferation and migration and capillary morphogenesis. The newly formed blood vessels provide nutrients and oxygen to the tumor, increasing its growth. Thus, angiogenesis plays a key role in cancer progression and development of metastases. An important growth factor that promotes angiogenesis and participates in a variety of physiological and pathological processes is the vascular endothelial growth factor (VEGF-A or VEGF). Overexpression of VEGF results in increased angiogenesis in normal and pathological conditions. The existence of an alternative site of splicing at the 3' untranslated region of the mRNA results in the expression of isoforms with a C-terminal region which are downregulated in tumors and may have differential inhibitory effects. This suggests that control of splicing can be an important regulatory mechanism of angiogenesis in cancer.
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Affiliation(s)
- P M Biselli-Chicote
- Genetics and Molecular Biology Research Unit - UPGEM, Medical School of Sao Jose do Rio Preto - FAMERP, Av. Brigadeiro Faria Lima, 5416, Bloco U6, Sao Jose do Rio Preto, SP 15090-000, Brazil
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75
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Chen J, Li Z, Zhang S, Zhang R, Dassarath M, Wu G. Effects of exogenous VEGF(165)b on invasion and migration of human lung adenocarcinoma A549 cells. ACTA ACUST UNITED AC 2011; 31:619. [PMID: 22038350 DOI: 10.1007/s11596-011-0571-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Indexed: 01/19/2023]
Abstract
Vascular endothelial growth factor 165 (VEGF(165))-mediated autocrine stimulation of tumor cells enhances the progression to a malignant phenotype. VEGF(165)b competes with VEGF(165) and binds to vascular endothelial growth factor receptor (VEGFR), resulting in inhibition of downstream signal transduction pathways. This study was designed to investigate the role of VEGF(165)b in the migration and invasion of human lung adenocarcinoma A549 cells. The full-length of VEGF(165)b was constructed and cloned into an expression plasmid (pVEGF(165)b), and then transfected into A549 cells. Dimethylthiazolyl- 1 -2, 5-diphenyltetrazolium bromide (MTT) assay was used to detect the effect of VEGF(165)b on proliferation of transfected cells. Reverse transcription polymerase chain reaction (RT-PCR) was employed to examine the effect of VEGF(165)b on the expression of VEGF(165) in transfected cells. Wound-healing assays were used to investigate the effect of VEGF(165)b on migration of transfected cells. Matrix metalloproteinase (MMPs) activity assay and in vitro invasion assay were used to determine the role of VEGF(165)b in invasion of transfected cells. There was no significant change in proliferation of A549 cells after transfection of pVEGF(165)b, but the expression of VEGF(165), migration and invasion in A549 cells were inhibited. Furthermore, exogenous VEGF(165)b inhibited the activity of MMP9 in the supernatant of A549 cells and the subsequent invasion capacity of those cells. We therefore conclude that exogenous VEGF(165)b can inhibit the expression of VEGF(165), as well as the migration and invasion of A549 cells, but has no effect on the proliferation of A549 cells.
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Affiliation(s)
- Jing Chen
- Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Zhenyu Li
- Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Sheng Zhang
- Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Ruiguang Zhang
- Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Meera Dassarath
- Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.,Department of Oncology, Queen Victoria Hospital, Candos, Quatre-Bornes, Mauritius
| | - Gang Wu
- Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
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VEGF spliced variants: possible role of anti-angiogenesis therapy. J Nucleic Acids 2011; 2012:162692. [PMID: 22013509 PMCID: PMC3195439 DOI: 10.1155/2012/162692] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Revised: 07/27/2011] [Accepted: 07/29/2011] [Indexed: 01/13/2023] Open
Abstract
Angiogenesis has been targeted in retinopathies, psoriasis, and a variety of cancers (colon, breast, lung, and kidney). Among these tumour types, clear cell renal cell carcinomas (RCCs) are the most vascularized tumours due to mutations of the von Hippel Lindau gene resulting in HIF-1 alpha stabilisation and overexpression of Vascular Endothelial Growth Factor (VEGF). Surgical nephrectomy remains the most efficient curative treatment for patients with noninvasive disease, while VEGF targeting has resulted in varying degrees of success for treating metastatic disease. VEGF pre-mRNA undergoes alternative splicing generating pro-angiogenic isoforms. However, the recent identification of novel splice variants of VEGF with anti-angiogenic properties has provided some insight for the lack of current treatment efficacy. Here we discuss an explanation for the relapse to anti-angiogenesis treatment as being due to either an initial or acquired resistance to the therapy. We also discuss targeting angiogenesis via SR (serine/arginine-rich) proteins implicated in VEGF splicing.
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Impaired Angiogenesis in Systemic Sclerosis: The Emerging Role of the Antiangiogenic VEGF165b Splice Variant. Trends Cardiovasc Med 2011; 21:204-10. [DOI: 10.1016/j.tcm.2012.05.011] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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78
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Emmett MS, Dewing D, Pritchard-Jones RO. Angiogenesis and melanoma - from basic science to clinical trials. Am J Cancer Res 2011; 1:852-868. [PMID: 22016833 PMCID: PMC3196284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Accepted: 07/27/2011] [Indexed: 05/31/2023] Open
Abstract
The effective management of malignant melanoma has remained centred around the surgeon. The arrival of anti-angiogenic agents as the 'fourth' cancer treatment joining the ranks of surgery, chemotherapy and radiotherapy has been a source of renewed hope. This article provides an up-to-date review of the focus, state and rationale of clinical trials of anti-angiogenic therapies in metastatic malignant melanoma. Vascular Endothelial Growth Factor (VEGF) is by no means the only target, although perhaps the most extensively studied following the successful introduction of the anti-VEGF Antibody bevacizumab. This has been combined with other established therapies to try and improve outcomes in metastatic disease, and is being trialled in the UK to prevent metastasis in high-risk patients. We describe the encouraging preclinical work that lead to great enthusiasm for these agents, assess the key trials and their outcomes, discuss why these therapies have not revolutionised melanoma care and explore how they might be better targeted in the future.
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79
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Relevance of VEGF and nephrin expression in glomerular diseases. JOURNAL OF SIGNAL TRANSDUCTION 2011; 2011:718609. [PMID: 21808734 PMCID: PMC3144718 DOI: 10.1155/2011/718609] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Accepted: 05/25/2011] [Indexed: 12/23/2022]
Abstract
The glomerular filtration barrier is affected in a large number of acquired and inherited diseases resulting in extensive leakage of plasma albumin and larger proteins, leading to nephrotic syndrome and end-stage renal disease. Unfortunately, the molecular mechanisms governing the development of the nephrotic syndrome remain poorly understood. Here, I give an overview of recent investigations that have focused on characterizing the interrelationships between the slit diaphragm components and podocytes-secreted VEGF, which have a significant role for maintaining the normal podocyte structure and the integrity of the filtering barrier.
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80
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Ruffini F, Failla CM, Orecchia A, Bani MR, Dorio AS, Fortes C, Zambruno G, Graziani G, Giavazzi R, D'Atri S, Lacal PM. Expression of the soluble vascular endothelial growth factor receptor-1 in cutaneous melanoma: role in tumour progression. Br J Dermatol 2011; 164:1061-70. [PMID: 21198538 DOI: 10.1111/j.1365-2133.2010.10200.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Vascular endothelial growth factor (VEGF)-A, placenta growth factor (PlGF) and their corresponding membrane receptors are involved in autocrine and paracrine regulation of melanoma growth and metastasis. Besides the membrane receptors, a soluble form of the VEGF receptor (VEGFR)-1 (sVEGFR-1) has been identified, that behaves both as a decoy receptor, sequestering VEGF-A and PlGF, and as an extracellular matrix (ECM) molecule, promoting endothelial cell adhesion and migration through the interaction with α5β1 integrin. OBJECTIVES To analyse whether sVEGFR-1 plays a role during melanoma progression. METHODS sVEGFR-1 expression was evaluated in a panel of 36 melanoma cell lines and 11 primary human melanocyte cultures by quantitative real-time polymerase chain reaction analysis and in specimens of primary or metastatic melanoma lesions from 23 patients by immunohistochemical analysis. RESULTS sVEGFR-1 expression was highly upregulated in melanoma cell lines with respect to human melanocytes. Interestingly, cell lines obtained from cutaneous metastases showed a significant reduction of sVEGFR-1 expression, as compared with cell lines derived from primary tumours. These results were confirmed by immunohistochemical analysis of sections from primary skin melanomas and the corresponding cutaneous metastases, suggesting that modulation of sVEGFR-1 expression influences ECM invasion by melanoma cells and metastasis localization. Moreover, we provide evidence that adhesion of melanoma cells to sVEGFR-1 is favoured by the activation of a VEGF-A/VEGFR-2 autocrine loop. CONCLUSIONS Our data strongly suggest that sVEGFR-1 plays a role in melanoma progression and that low sVEGFR-1/VEGF-A and sVEGFR-1/transmembrane VEGFR-1 ratios might predict a poor outcome in patients with melanoma.
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Affiliation(s)
- F Ruffini
- Laboratory of Molecular Oncology, Istituto Dermopatico dell'Immacolata-IRCCS, 00167 Rome, Italy
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81
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Manetti M, Guiducci S, Romano E, Ceccarelli C, Bellando-Randone S, Conforti ML, Ibba-Manneschi L, Matucci-Cerinic M. Overexpression of VEGF165b, an inhibitory splice variant of vascular endothelial growth factor, leads to insufficient angiogenesis in patients with systemic sclerosis. Circ Res 2011; 109:e14-26. [PMID: 21636803 DOI: 10.1161/circresaha.111.242057] [Citation(s) in RCA: 133] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
RATIONALE Systemic sclerosis (SSc) is characterized by widespread microangiopathy, fibrosis, and autoimmunity. Despite the lack of angiogenesis, the expression of vascular endothelial growth factor A (VEGF) was shown to be upregulated in SSc skin and circulation; however, previous studies did not distinguish between proangiogenic VEGF(165) and antiangiogenic VEGF(165)b isoforms, which are generated by alternative splicing in the terminal exon of VEGF pre-RNA. OBJECTIVE We investigated whether VEGF isoform expression could be altered in skin and circulation of patients with SSc. METHODS AND RESULTS Here, we show that the endogenous antiangiogenic VEGF(165)b splice variant is selectively overexpressed at both the mRNA and protein levels in SSc skin. Elevated VEGF(165)b expression correlated with increased expression of profibrotic transforming growth factor-β1 and serine/arginine protein 55 splicing factor in keratinocytes, fibroblasts, endothelial cells, and perivascular inflammatory cells. Circulating levels of VEGF(165)b were significantly higher in patients with SSc than in control subjects. Microvascular endothelial cells (MVECs) isolated from SSc skin expressed and released higher levels of VEGF(165)b than healthy MVECs. Transforming growth factor-β1 upregulated the expression of VEGF(165)b and serine/arginine protein 55 in both SSc and healthy MVECs. In SSc MVECs, VEGF receptor-2 was overexpressed, but its phosphorylation was impaired. Recombinant VEGF(165)b and SSc-MVEC-conditioned medium inhibited VEGF(165)-mediated VEGF receptor-2 phosphorylation and capillary morphogenesis in healthy MVECs. The addition of anti-VEGF(165)b blocking antibodies abrogated the antiangiogenic effect of SSc-MVEC-conditioned medium. Capillary morphogenesis was severely impaired in SSc MVECs and could be ameliorated by treatment with recombinant VEGF(165) and anti-VEGF(165)b blocking antibodies. CONCLUSIONS In SSc, a switch from proangiogenic to antiangiogenic VEGF isoforms may have a crucial role in the insufficient angiogenic response to chronic ischemia.
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Affiliation(s)
- Mirko Manetti
- Department of Anatomy, Histology and Forensic Medicine, University of Florence, Viale G.B. Morgagni 85, Florence, Italy.
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Holmes W, Mishra A, Gorst C, Liew S. Propranolol as first-line treatment for rapidly proliferating Infantile Haemangiomas. J Plast Reconstr Aesthet Surg 2011; 64:445-51. [DOI: 10.1016/j.bjps.2010.07.009] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Accepted: 07/16/2010] [Indexed: 11/27/2022]
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83
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Li ZY, Zhu F, Hu JL, Peng G, Chen J, Zhang S, Chen X, Zhang RG, Chen LJ, Liu P, Luo M, Sun ZH, Ren JH, Huang LL, Wu G. Sp1 inhibition-mediated upregulation of VEGF165b induced by rh-endostatin enhances antiangiogenic and anticancer effect of rh-endostatin in A549. Tumour Biol 2011; 32:677-87. [DOI: 10.1007/s13277-011-0168-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2010] [Accepted: 02/28/2011] [Indexed: 12/11/2022] Open
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84
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David CJ, Manley JL. Alternative pre-mRNA splicing regulation in cancer: pathways and programs unhinged. Genes Dev 2011; 24:2343-64. [PMID: 21041405 DOI: 10.1101/gad.1973010] [Citation(s) in RCA: 621] [Impact Index Per Article: 47.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Alternative splicing of mRNA precursors is a nearly ubiquitous and extremely flexible point of gene control in humans. It provides cells with the opportunity to create protein isoforms of differing, even opposing, functions from a single gene. Cancer cells often take advantage of this flexibility to produce proteins that promote growth and survival. Many of the isoforms produced in this manner are developmentally regulated and are preferentially re-expressed in tumors. Emerging insights into this process indicate that pathways that are frequently deregulated in cancer often play important roles in promoting aberrant splicing, which in turn contributes to all aspects of tumor biology.
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Affiliation(s)
- Charles J David
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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85
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Woolard J, Vousden W, Moss SJ, Krishnakumar A, Gammons MVR, Nowak DG, Dixon N, Micklefield J, Spannhoff A, Bedford MT, Gregory MA, Martin CJ, Leadlay PF, Zhang MQ, Harper SJ, Bates DO, Wilkinson B. Borrelidin modulates the alternative splicing of VEGF in favour of anti-angiogenic isoforms. Chem Sci 2011; 2011:273-278. [PMID: 22822423 PMCID: PMC3399765 DOI: 10.1039/c0sc00297f] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The polyketide natural product borrelidin 1 is a potent inhibitor of angiogenesis and spontaneous metastasis. Affinity biopanning of a phage display library of colon tumor cell cDNAs identified the tandem WW domains of spliceosome-associated protein formin binding protein 21 (FBP21) as a novel molecular target of borrelidin, suggesting that borrelidin may act as a modulator of alternative splicing. In support of this idea, 1, and its more selective analog 2, bound to purified recombinant WW domains of FBP21. They also altered the ratio of vascular endothelial growth factor (VEGF) isoforms in retinal pigmented endothelial (RPE) cells in favour of anti-angiogenic isoforms. Transfection of RPE cells with FBP21 altered the ratio in favour of pro-angiogenic VEGF isoforms, an effect inhibited by 2. These data implicate FBP21 in the regulation of alternative splicing and suggest the potential of borrelidin analogs as tools to deconvolute key steps of spliceosome function.
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Affiliation(s)
- Jeanette Woolard
- Microvascular Research Laboratories, Bristol Heart Institute, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Southwell Street Bristol, BS2 8EJ, UK. Fax: +44 (0)117 9288151; Tel: +44 (0)117 9289818;
| | - William Vousden
- Biotica, Chesterford Research Park, Cambridge, CB10 1XL, UK. Fax: +44 (0)1799 532921; Tel: +44 (0)1799 532925;
| | - Steven J. Moss
- Biotica, Chesterford Research Park, Cambridge, CB10 1XL, UK. Fax: +44 (0)1799 532921; Tel: +44 (0)1799 532925;
| | - Arjun Krishnakumar
- Microvascular Research Laboratories, Bristol Heart Institute, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Southwell Street Bristol, BS2 8EJ, UK. Fax: +44 (0)117 9288151; Tel: +44 (0)117 9289818;
| | - Melissa VR Gammons
- Microvascular Research Laboratories, Bristol Heart Institute, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Southwell Street Bristol, BS2 8EJ, UK. Fax: +44 (0)117 9288151; Tel: +44 (0)117 9289818;
| | - David G Nowak
- Microvascular Research Laboratories, Bristol Heart Institute, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Southwell Street Bristol, BS2 8EJ, UK. Fax: +44 (0)117 9288151; Tel: +44 (0)117 9289818;
| | - Neil Dixon
- School of Chemistry and Manchester Interdisciplinary Biocentre, University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
| | - Jason Micklefield
- School of Chemistry and Manchester Interdisciplinary Biocentre, University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
| | - Astrid Spannhoff
- The University of Texas M.D. Anderson Cancer Center, Science Park-Research Division, Smithville, Texas 78957, USA
| | - Mark T. Bedford
- The University of Texas M.D. Anderson Cancer Center, Science Park-Research Division, Smithville, Texas 78957, USA
| | - Matthew A. Gregory
- Biotica, Chesterford Research Park, Cambridge, CB10 1XL, UK. Fax: +44 (0)1799 532921; Tel: +44 (0)1799 532925;
| | - Christine J. Martin
- Biotica, Chesterford Research Park, Cambridge, CB10 1XL, UK. Fax: +44 (0)1799 532921; Tel: +44 (0)1799 532925;
| | - Peter F. Leadlay
- Department of Biochemistry, 80 Tennis Court Road, University of Cambridge, Cambridge CB2 1GA, UK
| | - Ming Q. Zhang
- Biotica, Chesterford Research Park, Cambridge, CB10 1XL, UK. Fax: +44 (0)1799 532921; Tel: +44 (0)1799 532925;
| | - Steven J. Harper
- Microvascular Research Laboratories, Bristol Heart Institute, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Southwell Street Bristol, BS2 8EJ, UK. Fax: +44 (0)117 9288151; Tel: +44 (0)117 9289818;
| | - David O. Bates
- Microvascular Research Laboratories, Bristol Heart Institute, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Southwell Street Bristol, BS2 8EJ, UK. Fax: +44 (0)117 9288151; Tel: +44 (0)117 9289818;
| | - Barrie Wilkinson
- Biotica, Chesterford Research Park, Cambridge, CB10 1XL, UK. Fax: +44 (0)1799 532921; Tel: +44 (0)1799 532925;
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Catena R, Larzabal L, Larrayoz M, Molina E, Hermida J, Agorreta J, Montes R, Pio R, Montuenga LM, Calvo A. VEGF₁₂₁b and VEGF₁₆₅b are weakly angiogenic isoforms of VEGF-A. Mol Cancer 2010; 9:320. [PMID: 21194429 PMCID: PMC3022671 DOI: 10.1186/1476-4598-9-320] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Accepted: 12/31/2010] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Different isoforms of VEGF-A (mainly VEGF₁₂₁, VEGF₁₆₅ and VEGF189) have been shown to display particular angiogenic properties in the generation of a functional tumor vasculature. Recently, a novel class of VEGF-A isoforms, designated as VEGF(xxx)b, generated through alternative splicing, have been described. Previous studies have suggested that these isoforms may inhibit angiogenesis. In the present work we have produced recombinant VEGF₁₂₁/₁₆₅b proteins in the yeast Pichia pastoris and constructed vectors to overexpress these isoforms and assess their angiogenic potential. RESULTS Recombinant VEGF₁₂₁/₁₆₅b proteins generated either in yeasts or mammalian cells activated VEGFR2 and its downstream effector ERK1/2, although to a lesser extent than VEGF₁₆₅. Furthermore, treatment of endothelial cells with VEGF₁₂₁/₁₆₅b increased cell proliferation compared to untreated cells, although such stimulation was lower than that induced by VEGF₁₆₅. Moreover, in vivo angiogenesis assays confirmed angiogenesis stimulation by VEGF₁₂₁/₁₆₅b isoforms. A549 and PC-3 cells overexpressing VEGF₁₂₁b or VEGF₁₆₅b (or carrying the PCDNA3.1 empty vector, as control) and xenotransplanted into nude mice showed increased tumor volume and angiogenesis compared to controls. To assess whether the VEGF(xxx)b isoforms are differentially expressed in tumors compared to healthy tissues, immunohistochemical analysis was conducted on a breast cancer tissue microarray. A significant increase (p < 0.05) in both VEGF(xxx)b and total VEGF-A protein expression in infiltrating ductal carcinomas compared to normal breasts was observed. A positive significant correlation (r = 0.404, p = 0.033) between VEGF(xxx)b and total VEGF-A was found. CONCLUSIONS Our results demonstrate that VEGF₁₂₁/₁₆₅b are not anti-angiogenic, but weakly angiogenic isoforms of VEGF-A. In addition, VEGF(xxx)b isoforms are up-regulated in breast cancer in comparison with non malignant breast tissues. These results are to be taken into account when considering a possible use of VEGF₁₂₁/₁₆₅b-based therapies in patients.
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Affiliation(s)
- Raúl Catena
- Laboratory of Novel Therapeutic Targets, Division of Oncology, Center for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain
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87
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Merdzhanova G, Gout S, Keramidas M, Edmond V, Coll JL, Brambilla C, Brambilla E, Gazzeri S, Eymin B. The transcription factor E2F1 and the SR protein SC35 control the ratio of pro-angiogenic versus antiangiogenic isoforms of vascular endothelial growth factor-A to inhibit neovascularization in vivo. Oncogene 2010; 29:5392-403. [PMID: 20639906 DOI: 10.1038/onc.2010.281] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The transcription factor E2F1 has a crucial role in the control of cell growth and has been shown to regulate neoangiogenesis in a p53-dependent manner through inhibition of activity of the VEGF-A (vascular endothelial growth factor) promoter. Besides being regulated by transcription, VEGF-A is also highly regulated by pre-mRNA alternative splicing, resulting in the expression of several VEGF isoforms with either pro-(VEGF(xxx)) or anti-(VEGF(xxx)b) angiogenic properties. Recently, we identified the SR (Ser-Rich/Arg) protein SC35, a splicing factor, as a new transcriptional target of E2F1. Here, we show that E2F1 downregulates the activity of the VEGF-A promoter in tumour cells independently of p53, leading to a strong decrease in VEGF(xxx) mRNA levels. We further show that, strikingly, E2F1 alters the ratio of pro-VEGF(xxx) versus anti-VEGF(xxx)b angiogenic isoforms, favouring the antiangiogenic isoforms, by a mechanism involving the induction of SC35 expression. Finally, using lung tumour xenografts in nude mice, we provide evidence that E2F1 and SC35 proteins increase the VEGF(165)b/VEGF ratio and decrease tumour neovascularization in vivo. Overall, these findings highlight E2F1 and SC35 as two regulators of the VEGF(xxx)/VEGF(xxx)b angiogenic switch in human cancer cells, a role that could be crucial during tumour progression, as well as in tumour response to antiangiogenic therapies.
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Affiliation(s)
- G Merdzhanova
- INSERM, U823, Equipe 2 Bases Moléculaires de la Progression des Cancers du Poumon, Grenoble, France
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88
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Biomarkers: the useful and the not so useful--an assessment of molecular prognostic markers for cutaneous melanoma. J Invest Dermatol 2010; 130:1971-87. [PMID: 20555347 DOI: 10.1038/jid.2010.149] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Among individuals with localized (Stage I-II) melanoma, stratifying patients by a number of phenotypic variables (e.g., depth of invasion, ulceration) yields a wide range of 10-year melanoma-specific survival rates. With the possible exception of Ki-67, no molecular assessment is routinely used. However, there have been a tremendous number of studies assessing protein expression by immunohistochemistry toward the goal of better prediction of recurrence. In a previous systematic review, which required publication of multivariable prognostic models as a strict inclusion criterion, we identified 37 manuscripts that collectively reported on 62 proteins. Data for 324 proteins extracted from 418 manuscripts did not meet our inclusion criteria for that study, but are revisited here, emphasizing trends of protein expression across either melanocytic lesion progression or gradations of tumor thickness. These identified 101 additional proteins that stratify melanoma, organized according to the Hanahan and Weinberg functional capabilities of cancer.
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89
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Hua J, Spee C, Kase S, Rennel ES, Magnussen AL, Qiu Y, Varey A, Dhayade S, Churchill AJ, Harper SJ, Bates DO, Hinton DR. Recombinant human VEGF165b inhibits experimental choroidal neovascularization. Invest Ophthalmol Vis Sci 2010; 51:4282-8. [PMID: 20237252 DOI: 10.1167/iovs.09-4360] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
PURPOSE Vascular endothelial growth factor (VEGF-A) is the principal stimulator of angiogenesis in wet age-related macular degeneration (AMD). However, VEGF-A is generated by alternate splicing into two families, the proangiogenic VEGF-A(xxx) family and the antiangiogenic VEGF-A(xxx)b family. It is the proangiogenic family that is responsible for the blood vessel growth seen in AMD. METHODS To determine the role of antiangiogenic isoforms of VEGF-A as inhibitors of choroidal neovascularization, the authors used a model of laser-induced choroidal neovascularization in the mouse eye and investigated VEGF-A(165)b effects on endothelial cells and VEGFRs in vitro. RESULTS VEGF-A(165)b inhibited VEGF-A(165)-mediated endothelial cell migration with a dose effect similar to that of ranibizumab and bevacizumab and 200-fold more potent than that of pegaptanib. VEGF-A(165)b bound both VEGFR1 and VEGFR2 with affinity similar to that of VEGF-A(165). After laser injury, mice were injected either intraocularly or subcutaneously with recombinant human VEGF-A(165)b. Intraocular injection of rhVEGF-A(165)b gave a pronounced dose-dependent inhibition of fluorescein leakage, with an IC(50) of 16 pg/eye, neovascularization (IC(50), 0.8 pg/eye), and lesion as assessed by histologic staining (IC(50), 8 pg/eye). Subcutaneous administration of 100 microg twice a week also inhibited fluorescein leakage and neovascularization and reduced lesion size. CONCLUSIONS These results show that VEGF-A(165)b is a potent antiangiogenic agent in a mouse model of age-related macular degeneration and suggest that increasing the ratio of antiangiogenic-to-proangiogenic isoforms may be therapeutically effective in this condition.
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Affiliation(s)
- Jing Hua
- Microvascular Research Laboratories, Department of Physiology and Pharmacology, Bristol Heart Institute, School of Veterinary Sciences, University of Bristol, Bristol, UK
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Ciura J, Jagodziński PP. Butyrate increases the formation of anti-angiogenic vascular endothelial growth factor variants in human lung microvascular endothelial cells. Mol Biol Rep 2010; 37:3729-34. [PMID: 20213511 DOI: 10.1007/s11033-010-0026-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Accepted: 02/24/2010] [Indexed: 11/30/2022]
Abstract
The primary transcript of vascular endothelial growth factor (VEGF) can be alternatively spliced and translated to pro-angiogenic and anti-angiogenic VEGF variants. We investigated the effect of sodium butyrate (NaB) on pro-angiogenic and anti-angiogenic VEGF variants production in immortalized human lung microvascular endothelial cells (HLMEC). These cells were cultured in the absence or in the presence of NaB, followed by total RNA and protein isolation. The transcript and protein levels of pro-angiogenic and anti-angiogenic VEGF variants were evaluated by reverse transcription, real-time quantitative PCR and western blot analysis. We found that NaB significantly increased the anti-angiogenic transcript and protein levels of the VEGF 121b, VEGF165b and VEGF189b variants in HLMEC cells. We did not find the pro-angiogenic VEGF189a transcript variant either in control or NaB treated cells. By contrast, the pro-angiogenic VEGF121a and VEGF165a transcript variants were present in HLMEC cells, but their levels were slightly modulated in the cells treated with NaB compared to controls. Since anti-angiogenic VEGF variants inhibit angiogenesis and tumour progression, and NaB is considered an anticancer drug, our findings may have clinical significance.
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Affiliation(s)
- J Ciura
- Department of Biochemistry and Molecular Biology, Poznan University of Medical Sciences, 6 Swiecickiego St., 60-781, Poznan, Poland
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91
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Qiu Y, Hoareau-Aveilla C, Oltean S, Harper SJ, Bates DO. The anti-angiogenic isoforms of VEGF in health and disease. Biochem Soc Trans 2009; 37:1207-13. [PMID: 19909248 PMCID: PMC2882696 DOI: 10.1042/bst0371207] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Anti-angiogenic VEGF (vascular endothelial growth factor) isoforms, generated from differential splicing of exon 8, are widely expressed in normal human tissues but down-regulated in cancers and other pathologies associated with abnormal angiogenesis (cancer, diabetic retinopathy, retinal vein occlusion, the Denys-Drash syndrome and pre-eclampsia). Administration of recombinant VEGF(165)b inhibits ocular angiogenesis in mouse models of retinopathy and age-related macular degeneration, and colorectal carcinoma and metastatic melanoma. Splicing factors and their regulatory molecules alter splice site selection, such that cells can switch from the anti-angiogenic VEGF(xxx)b isoforms to the pro-angiogenic VEGF(xxx) isoforms, including SRp55 (serine/arginine protein 55), ASF/SF2 (alternative splicing factor/splicing factor 2) and SRPK (serine arginine domain protein kinase), and inhibitors of these molecules can inhibit angiogenesis in the eye, and splice site selection in cancer cells, opening up the possibility of using splicing factor inhibitors as novel anti-angiogenic therapeutics. Endogenous anti-angiogenic VEGF(xxx)b isoforms are cytoprotective for endothelial, epithelial and neuronal cells in vitro and in vivo, suggesting both an improved safety profile and an explanation for unpredicted anti-VEGF side effects. In summary, C-terminal distal splicing is a key component of VEGF biology, overlooked by the vast majority of publications in the field, and these findings require a radical revision of our understanding of VEGF biology in normal human physiology.
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Affiliation(s)
- Yan Qiu
- Microvascular Research Laboratories, Bristol Heart Institute, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Southwell Street, Bristol BS2 8EJ, U.K
| | - Coralie Hoareau-Aveilla
- Microvascular Research Laboratories, Bristol Heart Institute, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Southwell Street, Bristol BS2 8EJ, U.K
| | - Sebastian Oltean
- Microvascular Research Laboratories, Bristol Heart Institute, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Southwell Street, Bristol BS2 8EJ, U.K
| | - Steven J. Harper
- Microvascular Research Laboratories, Bristol Heart Institute, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Southwell Street, Bristol BS2 8EJ, U.K
| | - David O. Bates
- Microvascular Research Laboratories, Bristol Heart Institute, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Southwell Street, Bristol BS2 8EJ, U.K
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Nowak DG, Amin EM, Rennel ES, Hoareau-Aveilla C, Gammons M, Damodoran G, Hagiwara M, Harper SJ, Woolard J, Ladomery MR, Bates DO. Regulation of vascular endothelial growth factor (VEGF) splicing from pro-angiogenic to anti-angiogenic isoforms: a novel therapeutic strategy for angiogenesis. J Biol Chem 2009; 285:5532-40. [PMID: 19906640 PMCID: PMC2820781 DOI: 10.1074/jbc.m109.074930] [Citation(s) in RCA: 162] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Vascular endothelial growth factor (VEGF) is produced either as a pro-angiogenic or anti-angiogenic protein depending upon splice site choice in the terminal, eighth exon. Proximal splice site selection (PSS) in exon 8 generates pro-angiogenic isoforms such as VEGF165, and distal splice site selection (DSS) results in anti-angiogenic isoforms such as VEGF165b. Cellular decisions on splice site selection depend upon the activity of RNA-binding splice factors, such as ASF/SF2, which have previously been shown to regulate VEGF splice site choice. To determine the mechanism by which the pro-angiogenic splice site choice is mediated, we investigated the effect of inhibition of ASF/SF2 phosphorylation by SR protein kinases (SRPK1/2) on splice site choice in epithelial cells and in in vivo angiogenesis models. Epithelial cells treated with insulin-like growth factor-1 (IGF-1) increased PSS and produced more VEGF165 and less VEGF165b. This down-regulation of DSS and increased PSS was blocked by protein kinase C inhibition and SRPK1/2 inhibition. IGF-1 treatment resulted in nuclear localization of ASF/SF2, which was blocked by SPRK1/2 inhibition. Pull-down assay and RNA immunoprecipitation using VEGF mRNA sequences identified an 11-nucleotide sequence required for ASF/SF2 binding. Injection of an SRPK1/2 inhibitor reduced angiogenesis in a mouse model of retinal neovascularization, suggesting that regulation of alternative splicing could be a potential therapeutic strategy in angiogenic pathologies.
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Affiliation(s)
- Dawid G Nowak
- Microvascular Research Laboratories, Bristol Heart Institute, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Bristol BS2 8EJ, United Kingdom
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Wu FTH, Stefanini MO, Mac Gabhann F, Kontos CD, Annex BH, Popel AS. A systems biology perspective on sVEGFR1: its biological function, pathogenic role and therapeutic use. J Cell Mol Med 2009; 14:528-52. [PMID: 19840194 PMCID: PMC3039304 DOI: 10.1111/j.1582-4934.2009.00941.x] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Angiogenesis is the growth of new capillaries from pre-existent microvasculature. A wide range of pathological conditions, from atherosclerosis to cancer, can be attributed to either excessive or deficient angiogenesis. Central to the physiological regulation of angiogenesis is the vascular endothelial growth factor (VEGF) system – its ligands and receptors (VEGFRs) are thus prime molecular targets of pro-angiogenic and anti-angiogenic therapies. Of growing interest as a prognostic marker and therapeutic target in angiogenesis-dependent diseases is soluble VEGF receptor-1 (sVEGFR1, also known as sFlt-1) – a truncated version of the cell membrane-spanning VEGFR1. For instance, it is known that sVEGFR1 is involved in the endothelial dysfunction characterizing the pregnancy disorder of pre-eclampsia, and sVEGFR1’s therapeutic potential as an anti-angiogenic agent is being evaluated in pre-clinical models of cancer. This mini review begins with an examination of the protein domain structure and biomolecular interactions of sVEGFR1 in relation to the full-length VEGFR1. A synopsis of known and inferred physiological and pathological roles of sVEGFR1 is then given, with emphasis on the utility of computational systems biology models in deciphering the molecular mechanisms by which sVEGFR1’s purported biological functions occur. Finally, we present the need for a systems biology perspective in interpreting circulating VEGF and sVEGFR1 concentrations as surrogate markers of angiogenic status in angiogenesis-dependent diseases.
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Affiliation(s)
- Florence T H Wu
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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94
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Woolard J, Bevan HS, Harper SJ, Bates DO. Molecular diversity of VEGF-A as a regulator of its biological activity. Microcirculation 2009; 16:572-92. [PMID: 19521900 PMCID: PMC2929464 DOI: 10.1080/10739680902997333] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The vascular endothelial growth factor (VEGF) family of proteins regulates blood flow, growth, and function in both normal physiology and disease processes. VEGF-A is alternatively spliced to form multiple isoforms, in two subfamilies, that have specific, novel functions. Alternative splicing of exons 5-7 of the VEGF gene generates forms with differing bioavailability and activities, whereas alternative splice-site selection in exon 8 generates proangiogenic, termed VEGF(xxx), or antiangiogenic proteins, termed VEGF(xxx)b. Despite its name, emerging roles for VEGF isoforms on cell types other than endothelium have now been identified. Although VEGF-A has conventionally been considered to be a family of proangiogenic, propermeability vasodilators, the identification of effects on nonendothelial cells, and the discovery of the antiangiogenic subfamily of splice isoforms, has added further complexity to their regulation of microvascular function. The distally spliced antiangiogenic isoforms are expressed in normal human tissue, but downregulated in angiogenic diseases, such as cancer and proliferative retinopathy, and in developmental pathologies, such as Denys Drash syndrome and preeclampsia. Here, we examine the molecular diversity of VEGF-A as a regulator of its biological activity and compare the role of the pro- and antiangiogenic VEGF-A splice isoforms in both normal and pathophysiological processes.
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Affiliation(s)
- Jeanette Woolard
- Department of Physiology and Pharmacology, Bristol Heart Institute, School of Veterinary Sciences, University of Bristol, Bristol, UK.
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Structure-function analysis of VEGF receptor activation and the role of coreceptors in angiogenic signaling. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1804:567-80. [PMID: 19761875 DOI: 10.1016/j.bbapap.2009.09.002] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 06/25/2009] [Revised: 08/22/2009] [Accepted: 09/04/2009] [Indexed: 12/11/2022]
Abstract
Vascular endothelial growth factors (VEGFs) constitute a family of six polypeptides, VEGF-A, -B, -C, -D, -E and PlGF, that regulate blood and lymphatic vessel development. VEGFs specifically bind to three type V receptor tyrosine kinases (RTKs), VEGFR-1, -2 and -3, and to coreceptors such as neuropilins and heparan sulfate proteoglycans (HSPG). VEGFRs are activated upon ligand-induced dimerization mediated by the extracellular domain (ECD). A study using receptor constructs carrying artificial dimerization-promoting transmembrane domains (TMDs) showed that receptor dimerization is necessary, but not sufficient, for receptor activation and demonstrates that distinct orientation of receptor monomers is required to instigate transmembrane signaling. Angiogenic signaling by VEGF receptors also depends on cooperation with specific coreceptors such as neuropilins and HSPG. A number of VEGF isoforms differ in binding to coreceptors, and ligand-specific signal output is apparently the result of the specific coreceptor complex assembled by a particular VEGF isoform. Here we discuss the structural features of VEGF family ligands and their receptors in relation to their distinct signal output and angiogenic potential.
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96
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Rennel ES, Harper SJ, Bates DO. Therapeutic potential of manipulating VEGF splice isoforms in oncology. Future Oncol 2009; 5:703-12. [PMID: 19519209 DOI: 10.2217/fon.09.33] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Anti-angiogenic therapies currently revolve around targeting vascular endothelial growth factor-A (VEGF-A) or its receptors. These therapies are effective to some degree, but have low response rates and poor side-effect profiles. Part of these problems is likely to be due to their lack of specificity between pro- and anti-angiogenic isoforms, and their nonspecific effects on proactive, pleiotropic survival and maintenance roles of VEGF-A in endothelial and other cell types. An alternative approach, and one which has recently been shown to be effective in animal models of neovascularization in the eye, is to target the mechanisms by which the cell generates pro-angiogenic splice forms of VEGF-A, its receptors and, co-incidentally, by targeting the upstream processes, other oncogenes that have antagonistic splice isoforms. The concept here is to target the splicing mechanisms that control splice site choice in the VEGF-A mRNA. Recent evidence on the pharmacological possibilities of such splice factors is described.
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Affiliation(s)
- Emma S Rennel
- Microvascular Research Laboratories, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Bristol, UK.
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97
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VEGF(121)b, a new member of the VEGF(xxx)b family of VEGF-A splice isoforms, inhibits neovascularisation and tumour growth in vivo. Br J Cancer 2009; 101:1183-93. [PMID: 19707198 PMCID: PMC2768092 DOI: 10.1038/sj.bjc.6605249] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Background: The key mediator of new vessel formation in cancer and other diseases is VEGF-A. VEGF-A exists as alternatively spliced isoforms - the pro-angiogenic VEGFxxx family generated by exon 8 proximal splicing, and a sister family, termed VEGFxxxb, exemplified by VEGF165b, generated by distal splicing of exon 8. However, it is unknown whether this anti-angiogenic property of VEGF165b is a general property of the VEGFxxxb family of isoforms. Methods: The mRNA and protein expression of VEGF121b was studied in human tissue. The effect of VEGF121b was analysed by saturation binding to VEGF receptors, endothelial migration, apoptosis, xenograft tumour growth, pre-retinal neovascularisation and imaging of biodistribution in tumour-bearing mice with radioactive VEGF121b. Results: The existence of VEGF121b was confirmed in normal human tissues. VEGF121b binds both VEGF receptors with similar affinity as other VEGF isoforms, but inhibits endothelial cell migration and is cytoprotective to endothelial cells through VEGFR-2 activation. Administration of VEGF121b normalised retinal vasculature by reducing both angiogenesis and ischaemia. VEGF121b reduced the growth of xenografted human colon tumours in association with reduced microvascular density, and an intravenous bolus of VEGF121b is taken up into colon tumour xenografts. Conclusion: Here we identify a second member of the family, VEGF121b, with similar properties to those of VEGF165b, and underline the importance of the six amino acids of exon 8b in the anti-angiogenic activity of the VEGFxxxb isoforms.
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98
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Kim WC, Lee CH. The role of mammalian ribonucleases (RNases) in cancer. Biochim Biophys Acta Rev Cancer 2009; 1796:99-113. [PMID: 19463900 DOI: 10.1016/j.bbcan.2009.05.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2008] [Revised: 05/08/2009] [Accepted: 05/13/2009] [Indexed: 01/01/2023]
Abstract
Ribonucleases (RNases) are a group of enzymes that cleave RNAs at phosphodiester bonds resulting in remarkably diverse biological consequences. This review focuses on mammalian RNases that are capable of, or potentially capable of, cleaving messenger RNA (mRNA) as well as other RNAs in cells and play roles in the development of human cancers. The aims of this review are to provide an overview of the roles of currently known mammalian RNases, and the evidence that associate them as regulators of tumor development. The roles of these RNases as oncoproteins and/or tumor suppressors in influencing cell growth, apoptosis, angiogenesis, and other cellular hallmarks of cancer will be presented and discussed. The RNases under discussion include RNases from the conventional mRNA decay pathways, RNases that are activated under cellular stress, RNases from the miRNA pathway, and RNases with multifunctional activity.
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Affiliation(s)
- Wan-Cheol Kim
- Chemistry Program, University of Northern British Columbia, 3333 University Way, Prince George, BC, Canada V2N 4Z9
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99
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Varey AH, Dunn DB. Comment on: Akhavani MA, Sivakumar B, Paleolog EM and Kang, N: ‘Angiogenesis and plastic surgery’ J Plast Reconstr Aesthet Surg 2008;61:1425–37. J Plast Reconstr Aesthet Surg 2009; 62:710. [DOI: 10.1016/j.bjps.2008.12.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2008] [Accepted: 12/12/2008] [Indexed: 11/15/2022]
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100
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Gould Rothberg BE, Bracken MB, Rimm DL. Tissue biomarkers for prognosis in cutaneous melanoma: a systematic review and meta-analysis. J Natl Cancer Inst 2009; 101:452-74. [PMID: 19318635 DOI: 10.1093/jnci/djp038] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
In the clinical management of early-stage cutaneous melanoma, it is critical to determine which patients are cured by surgery alone and which should be treated with adjuvant therapy. To assist in this decision, many groups have made an effort to use molecular information. However, although there are hundreds of studies that have sought to assess the potential prognostic value of molecular markers in predicting the course of cutaneous melanoma, at this time, no molecular method to improve risk stratification is part of recommended clinical practice. To help understand this disconnect, we conducted a systematic review and meta-analysis of the published literature that reported immunohistochemistry-based protein biomarkers of melanoma outcome. Three parallel search strategies were applied to the PubMed database through January 15, 2008, to identify cohort studies that reported associations between immunohistochemical expression and survival outcomes in melanoma that conformed to the REMARK criteria. Of the 102 cohort studies, we identified only 37 manuscripts, collectively describing 87 assays on 62 distinct proteins, which met all inclusion criteria. Promising markers that emerged included melanoma cell adhesion molecule (MCAM)/MUC18 (all-cause mortality [ACM] hazard ratio [HR] = 16.34; 95% confidence interval [CI] = 3.80 to 70.28), matrix metalloproteinase-2 (melanoma-specific mortality [MSM] HR = 2.6; 95% CI = 1.32 to 5.07), Ki-67 (combined ACM HR = 2.66; 95% CI = 1.41 to 5.01), proliferating cell nuclear antigen (ACM HR = 2.27; 95% CI = 1.56 to 3.31), and p16/INK4A (ACM HR = 0.29; 95% CI = 0.10 to 0.83, MSM HR = 0.4; 95% CI = 0.24 to 0.67). We further noted incomplete adherence to the REMARK guidelines: 14 of 27 cohort studies that failed to adequately report their methods and nine studies that failed to either perform multivariable analyses or report their risk estimates were published since 2005.
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