Towards high-throughput functional target discovery in angiogenesis research

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Angiogenesis is a hallmark of malignancies and other proliferative diseases, and inhibition of this process is considered to be a promising treatment strategy. Classical gene-expression analyses performed during the past decade have generated vast lists of genes associated with disease but have so far yielded only limited novel therapeutic targets for clinical applications. Recently, the focus has shifted from target identification, based on gene-expression analysis, to identification of genes, based on the function of the encoded protein. Disease-target genes can now be identified in a high-throughput fashion based on functional properties that are directly related to the disease phenotype. This new approach significantly shortens the time span for the development of therapeutic applications from the laboratory bench to the hospital bedside.

Section snippets

Identification of targets for angiogenesis modulation

Angiogenesis, the formation of novel blood vessels from pre-existing blood vessels, is a hallmark of numerous pathologies such as cancer, rheumatoid arthritis, endometriosis, atherosclerosis and diabetic retinopathy 1, 2. In normal tissues, blood vessels and capillaries are generally in a resting state, which is maintained by a fine-tuned balance of pro-angiogenic and anti-angiogenic factors present in the microenvironment. However, different stimuli can disturb this balance in favor of

Target validation: from gene to function

Gene- and protein-expression-profiling techniques have been applied to study molecular events in angiogenesis [6]. Differentially expressed molecules might serve as targets for therapeutic intervention. Validating the relevance of a target for therapeutic applications requires the establishment of a causative relationship between protein expression and/or function and the disease phenotype. This can be achieved by either blocking protein function or modulating protein-expression levels. In this

Functional-target discovery: from function to gene

The wealth of gene-expression data generated to date has presented the scientific community with the formidable challenge of functionally annotating the individual genes in a multitude of processes and diseases. Recently, diverse high-throughput methods have been shown to functionally annotate putative target molecules, overcoming these limitations. Advances in gene-library generation, transfection methods, miniaturization of assays, and screening techniques have provided the opportunity for

Functional genomics in angiogenesis research

Recent advances in high-throughput functional genomics will have a major impact on our future understanding of pathological and physiological angiogenesis. The shift in focus towards functional identification of putative therapeutic targets enables more-efficient clinical translation. Most techniques described in this review rely on efficient transfection of cells. This can be a complicating factor when studying some cell types, such as ECs. Recent developments in high-throughput

Concluding remarks

Functional validation tools, originally developed for the analysis of individual genes, have become useful for high-throughput functional identification with almost no limitations. In conclusion, the use of high-throughput gene-expression analysis, which only generates associative data rather than causative data, is being caught up by novel methods that enable direct functional linkage between the gene-expression level and the phenotype. Although technical challenges remain, recent progress has

Acknowledgements

This work was supported by a grant from the Research Institute for Growth and Development (GROW), Maastricht University. The study has been financially supported by the sixth EU Framework Programme (Integrated Project ‘Angiotargeting’; contract no. 504743) in the area of ‘Life sciences, genomics and biotechnology for health’.

Glossary

Antisense oligodeoxynucleotide (ODN):
a single-stranded, DNA-like molecule of 17–22 nucleotides in length that is complementary to its target mRNA and blocks protein translation by forming DNA–RNA duplexes.
Array:
a systematically arranged repertoire of DNA, cells or tissues. These arrays can be arranged in microtiter plates, or printed on glass slides or chips (microarray).
cDNA library:
a collection of cDNA sequences in separate vectors.
Expression library:
a collection of cDNA sequences

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