| 1. |
- Nowak-Sliwinska, Patrycja, et al.
(författare)
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Consensus guidelines for the use and interpretation of angiogenesis assays
- 2018
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Ingår i: Angiogenesis. - : Springer. - 0969-6970 .- 1573-7209. ; 21:3, s. 425-532
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Forskningsöversikt (refereegranskat)abstract
- The formation of new blood vessels, or angiogenesis, is a complex process that plays important roles in growth and development, tissue and organ regeneration, as well as numerous pathological conditions. Angiogenesis undergoes multiple discrete steps that can be individually evaluated and quantified by a large number of bioassays. These independent assessments hold advantages but also have limitations. This article describes in vivo, ex vivo, and in vitro bioassays that are available for the evaluation of angiogenesis and highlights critical aspects that are relevant for their execution and proper interpretation. As such, this collaborative work is the first edition of consensus guidelines on angiogenesis bioassays to serve for current and future reference.
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| 3. |
- Sikkema, A. H., et al.
(författare)
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Vascular endothelial growth factor receptor 2 (VEGFR-2) signalling activity in paediatric pilocytic astrocytoma is restricted to tumour endothelial cells
- 2011
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Ingår i: Neuropathology and Applied Neurobiology. - : Wiley. - 0305-1846 .- 1365-2990. ; 37:5, s. 538-548
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Tumours depend on angiogenesis for enhanced tumour cell survival and progression. Vascular endothelial growth factor receptor (VEGFR) signalling plays a major part in this process. Previously, we evaluated tyrosine kinase activity in paediatric brain tumour tissue lysates using a peptide microarray containing 144 different tyrosine kinase peptide substrates. When applied to paediatric pilocytic astrocytoma tissue, this analysis revealed extensive phosphorylation of VEGFR-derived peptides. The aim of the current study was to validate this result and determine the presence of VEGFR-2 activity in paediatric pilocytic astrocytoma as the main VEGFR in terms of mitogenic signalling. In addition, the localization of VEGFR1-3 mRNA expression was assessed. Methods: VEGFR-2 phosphorylation was determined by adopting a proximity ligation assay approach. Enrichment of endothelial markers and VEGFRs in tumour endothelium was determined by quantitative polymerase chain reaction (qPCR) analysis of laser-microdissected blood vessels. Results: Proximity ligation assays on tumour cryosections showed the presence of phosphorylation of VEGFR-2, which primarily localized to vascular endothelium. qPCR analysis of endothelial markers and VEGFRs showed a 13.6-fold average enrichment of VEGFR-2 expression in the laser-microdissected endothelium compared to whole tumour. Also the expression of VEGFR-1 and -3 was highly enriched in the endothelium fraction with an average fold-enrichment of 16.5 and 50.8 respectively. Conclusions: Phosphorylated VEGFR-2 is detected on endothelial cells in paediatric pilocytic astrocytoma. Furthermore, endothelial cells are the main source of VEGFR1-3 mRNA expression. This suggests a crucial role for VEGF/VEGFR-induced angiogenesis in the progression and maintenance of these tumours.
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| 4. |
- Cottarelli, Azzurra, et al.
(författare)
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Fgfbp1 promotes blood-brain barrier development by regulating collagen IV deposition and maintaining Wnt/beta-catenin signaling
- 2020
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Ingår i: Development. - : COMPANY BIOLOGISTS LTD. - 0950-1991 .- 1477-9129. ; 147:16
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Tidskriftsartikel (refereegranskat)abstract
- Central nervous system (CNS) blood vessels contain a functional blood-brain barrier (BBB) that is necessary for neuronal survival and activity. Although Wnt/beta-catenin signaling is essential for BBB development, its downstream targets within the neurovasculature remain poorly understood. To identify targets of Wnt/beta-catenin signaling underlying BBB maturation, we performed a microarray analysis that identified Fgfbp1 as a novel Wnt/beta-catenin-regulated gene in mouse brain endothelial cells (mBECs). Fgfbp1 is expressed in the CNS endothelium and secreted into the vascular basement membrane during BBB formation. Endothelial genetic ablation of Fgfbp1 results in transient hypervascularization but delays BBB maturation in specific CNSregions, as evidenced by both upregulation of Plvap and increased tracer leakage across the neurovasculature due to reduced Wnt/beta-catenin activity. In addition, collagen IV deposition in the vascular basement membrane is reduced in mutant mice, leading to defective endothelial cell-pericyte interactions. Fgfbp1 is required cell-autonomously in mBECs to concentrate Wnt ligands near cell junctions and promote maturation of their barrier properties in vitro. Thus, Fgfbp1 is a crucial extracellular matrix protein during BBB maturation that regulates cell-cell interactions and Wnt/beta-catenin activity.
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| 5. |
- Dimberg, J, et al.
(författare)
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Decreased levels of precursor transforming growth factor beta(1) in human colorectal cancer
- 2001
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Ingår i: International Journal of Molecular Medicine. - 1107-3756 .- 1791-244X. ; 7:6, s. 597-601
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Tidskriftsartikel (refereegranskat)abstract
- Transforming growth factor (TGF) beta (1) is a growth factor with wide-ranging effects on proliferation, differentiation, immunosuppression, apoptosis and matrix remodelling. TGF beta (1) seems to have an antitumorigenic role in the gastrointestinal tract but may also be associated with the development of colorectal cancer. Initially, TGF beta (1) is produced in a latent (precursor) form in epithelial cells and then is activated by a not clearly understood multistep process. In this study, we analysed precursor TGF beta (1) protein expression (n=40) and TGF beta (1) gene expression (n=49) in human colorectal adenocarcinomas and 49 normal adjacent tissue. Out of these 49 normal tissues 40 were matched. Western blot analysis revealed that the precursor TGF beta (1) protein levels were generally lower in colorectal cancerous tissue compared to adjacent noncancerous tissue (P <0.001). Furthermore, with real-time PCR our results cannot reflect a statistically significant difference in TGF beta (1) gene expression between the tumour tissue and normal tissue. These finds indicate that it is likely that there are mechanisms which control precursor TGF beta (1) protein expression by factor(s) at the level of pre-translation of the TGF beta (1) transcript and/or at the level of post-translation of the TGF beta (1) protein in the tumours. This process may be related to carcinogenesis and poses the question whether the suppression of the precursor TGF beta (1) is an early event, in vivo, in the human colorectal adenoma-carcinoma sequence.
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| 9. |
- Dimberg, Jan, et al.
(författare)
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Enhanced expression of cyclooxygenase-2 and nuclear beta-catenin are related to mutations in the APC gene in human colorectal cancer
- 2001
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Ingår i: Anticancer Research. - 0250-7005 .- 1791-7530. ; 21:2A, s. 911-915
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Tidskriftsartikel (refereegranskat)abstract
- Mutational inactivation of the human tumour suppressor gene adenomatous polyposis coli (APC) results in constitutive activation of beta -catenin/T cell factor-4 (Tcf-4) mediated transcription of target genes. Up-regulation of cyclooxygenase-2 (COX-2) protein is frequently found in human colorectal cancer (CRC). We analysed 38 CRC for mutations in APC and beta -catenin and found an association between APC mutations and elevated COX-2 levels. Furthermore, APC mutations were predominantly observed in tumour tissues from the rectum compared to tumours of colonic origin. Western blot analysis revealed that nuclear beta -catenin levels were generally higher in tumours with APC mutations compared to tumours with wild type APC. However, there was also a higher level of nuclear beta -catenin in tumour compared to normal tissue, hut nuclear Tcf-4 protein was constitutively expressed in tumour and normal tissue and showed no differences. An identified putative Tcf-4 binding element in the COX-2 promoter may partly explain the enhanced level of COX-2 and support the idea that COX-2 may be a downstream target of the APC/beta -catenin/Tcf-4 pathway.
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