%0 Journal Article
%T Inhibition of receptor tyrosine kinase signalling by small molecule agonist of T-cell protein tyrosine phosphatase
%A Elina Mattila
%A Heidi Marttila
%A Niko Sahlberg
%A Pekka Kohonen
%A Siri T£¿htinen
%A Pasi Halonen
%A Merja Per£¿l£¿
%A Johanna Ivaska
%J BMC Cancer
%D 2010
%I BioMed Central
%R 10.1186/1471-2407-10-7
%X We developed a high-throughput compatible assay to analyse activity of recombinant TCPTP in vitro. Using this assay we have screened 64280 small molecules to identify novel agonists for TCPTP. Dose-dependent response to TCPTP agonist was performed using the in vitro assay. Inhibition effects and specificity of TCPTP agonists were evaluated using TCPTP expressing and null mouse embryonic fibroblasts. Western blot analysis was used to evaluate attenuation of PDGFR¦Â and EGFR phosphorylation. Inhibition of VEGF signalling was analysed with VEGF-induced endothelial cell sprouting assays.From the screen we identified six TCPTP agonists. Two compounds competed with ¦Á1-cytoplasmic domain for binding to TCPTP, suggesting that they activate TCPTP similar to ¦Á1-cyt by disrupting the intra-molecular bond in TCPTP. Importantly, one of the compounds (spermidine) displayed specificity towards TCPTP in cells, since TCPTP -/- cells were 43-fold more resistant to the compound than TCPTP expressing cells. This compound attenuates PDGFR¦Â and VEGFR2 signalling in cells in a TCPTP-dependent manner and functions as a negative regulator of EGFR phosphorylation in cancer cells.In this study we showed that small molecules mimicking TCPTP-¦Á1 interaction can be used as TCPTP agonists. These data provide the first proof-of-concept description of the use of high-throughput screening to identify small molecule PTP activators that could function as RTK antagonists in cells.Cellular homeostasis is maintained by the coordinated actions of kinases and phosphatases. Aberrant activation of several kinases due to overexpression, amplification or activating mutations are the underlying causes of many human pathologies like inflammation and cancer [1]. Conversely, loss of the negative regulation exerted by phosphatases may lead to a similar outcome [2]. To date, many kinase inhibitors have been developed and several small molecule inhibitors and function blocking antibodies against receptor tyrosine kinas
%U http://www.biomedcentral.com/1471-2407/10/7