Book of Abstracts - Ruhr-Universität Bochum

OP-34
ISBOMC `10 5.7 – 9.7. 2010 Ruhr-Universität Bochum
RAPTA-T interacts with �1�1 integrin at the molecular level
Alletta Schmidt-Hederich, a Michael Grössl, c Alessia Masi, b Alberta Bergamo, b Gianni Sava, b Paul J.
Dyson, c and Johannes A. Eble *a
a Goethe University of Frankfurt, Faculty of Medicine, Center for Molecular Medicine, Vascular
Matrix Biology, Excellence Cluster CardioPulmonary System, Theodor-Stern-Kai 7, 60590
Frankfurt/Main, Germany. b Callerio Foundation, Via Fleming 31, 34127 Trieste, Italy. c Ècole
Polytechnique Fedèrale de Lausanne, Department of Chemistry and Chemical Engineering, 1015
Lausanne, Switzerland. E-mail: Eble@med.uni-frankfurt.de
Metal-based compounds, such as cisplatin and ruthenium complexes have been used as cytostatic
drugs in cancer treatment. These compounds are generally thought to target DNA and hence interfere
with the growth of highly proliferative tumor cells. However, recent experiments have suggested that
ruthenium compounds, such as RAPTA-T, additionally affect cellular interactions with the
extracellular matrix (ECM). Among cell adhesion molecules, integrins form a numerous and most
versatile family. They bind to ECM proteins in a divalent cation-dependent manner and thus mediate
cell-matrix interactions and regulate tissue-specific cell morphology, migration, cell survival and
proliferation. Therefore, they play key roles in various physiological situations and diseases, such as
tumor progression and metastasis.
To analyse the effects of ruthenium-based compounds, in particular RAPTA-T, on integrins at both
cellular and molecular level, we used cell attachment studies as well as cell-free protein interaction
assays with recombinant human integrins. Moreover, a test system to determine the binding of metal
organic compounds to integrins was established.
At the cellular level, RAPTA-T affected cell adhesion especially to the basement membrane collagen
IV and to fibronectin, which is mediated via the integrins �1�1 and �5�1, respectively. The isolated
integrins were affected in their binding properties towards their cognate ligands, depending on the
incubation time with RAPTA-T. Bioanalytical studies, such as gel filtration of �1�1 integrin with the
ruthenium compound followed by an on-line detection of ruthenium by inductively coupled plasma
mass spectrometry (ICP-MS), demonstrated that RAPTA-T binds to �1�1 integrin and alters its ability
to form higher aggregates. In parallel, the binding activity of �1�1 integrin is compromised.
Additional studies will be necessary in the future to elucidate the molecular mechanism.
50