Research line 2
Development of novel
angiogenesis inhibitors
The main aim of research line II
is to get more insight in the working mechanism(s) of angiostatic agents
and to employ this knowledge for the identification and development of
novel agents with therapeutic and diagnostic applications.
Development of synthetic cytokine-like angiogenesis inhibitors
Based on the ß-sheet structure
of the well-known angiogenesis inhibitor platelet factor-4 (PF4), a
library of beta-sheet forming peptides was designed in collaboration
with the Department of Biochemistry of the
University of
Minnesota (Prof. K.H. Mayo).
One of these de novo designed peptides, ßpep-25 or anginex, is a more
potent angiogenesis inhibitor as compared to native PF4. The in
vitro mechanism of action is inhibition of endothelial cell
proliferation, prevention of endothelial cell adhesion/migration and
subsequently the induction of apoptosis of the endothelial cells. In
vivo, anginex inhibits tumor growth by specifically targeting to
tumor vessels thus preventing tumor angiogenesis. Studies on the
structure-activity relationship of anginex have resulted in the
identification of the amino acids and regions within anginex that are
essential for the anti-angiogenesis function. This information has
resulted in the development of partial non-peptide ß-sheet mimetics of
anginex with similar or even improved anti-tumor activity. Currently,
these mimetics are being further developed in order to create
non-biological small-molecule pharmaceutical agents that can be applied
to different pathological disorders which are related to angiogenesis
such as rheumatoid arthritis, diabetic retinopathy and cardiovascular
diseases.
From: Dings et al. JNCI, 2006.
Identification of EC specific receptors and novel endogenous angiostatic
agents
In order to fully grasp the
mechanisms behind tumor specific inhibition of angiostatic compounds,
the identification of pathways that are targeted by these compounds is
of utmost importance. To identify cellular receptors for angiostatic
agents, yeast two-hybrid technology is used. In turn, candidate
receptors are used in yeast two-hybrid screens to discover novel
endogenous angiostatic proteins. Recently, this research has resulted in
the identification of galectin-1 as a target protein for the angiostatic
peptide anginex. In galectin-1 knockout mice we found that galectin-1 is
pivotal for tumor-angiogenesis. Furthermore, it was observed that the
knockout mice no longer respond to treatment with anginex strongly
suggesting that the galectin-1 is the major target for anginex. Current
research is focused to unravel the exact cellular mechanisms by which
galectin-1/anginex interaction inhibits endothelial cell function. In
addition, other angiostatic proteins are now used in our yeast
two-hybrid platform to identify their, yet unknown, receptors.
From: Thijssen et al. PNAS, 2006.
Molecular profiling of angiogenesis
In addition to the
identification of novel targets important in angiogenesis, a method has
been developed to obtain the angiogenesis expression profile of known
angiogenesis factors in tumor cells and tumor vasculature in vivo.
This method, employing the sensitivity and specificity of real-time PCR,
can be used to determine the interactions between host cells and donor
cells in vivo and it allows the analysis of the effects of
angiostatic treatment on either the tumor cells or the tumor
vasculature. Currently, for over 40 genes involved in angiogenesis,
primers sets are available for quantitative analysis of gene expression
including all known ligands and receptors involved in VEGF and
angiopoietin signaling. The profiling is almost routinely used in the
lab to get insight in the angiogenic potential of cells and tissue in
vitro and in vivo.
From: Thijssen et al. Exp. Cell Res., 2004.
From: Baldewijns et al. Br. J. Cancer, 2007. |
