Chondrosarcomas represent 20% of all primary bone
sarcomas, and many studies have attempted to unravel molecular targets for future development of new
therapies. The aim of this study was to investigate the expression/activation of
PDGFRalpha, PDGFRbeta and KIT
receptor tyrosine kinases (RTKs) as potential therapeutic targets in conventional central primary
chondrosarcomas (CCS). The expression of
PDGFRalpha, PDGFRbeta and KIT RTKs was detected in 16 CCSs using immunohistochemistry (IHC), and their level of expression and activation status were analysed by immunoprecipitation and western blot experiments.
PDGFRalpha, PDGFRbeta and KIT cDNAs were screened to verify the presence of activating mutations and the presence of the cognate
ligands was analysed by means of RT-PCR. RTK gene amplification was further studied by means of fluorescence in situ hybridization (FISH) analysis. The immunophenotyping and biochemical analyses showed that the CCSs co-expressed
PDGFRalpha and PDGFRbeta, with the latter showing definitively greater
protein expression and phosphorylation levels. PDGFRbeta was expressed but not activated in control healthy joint cartilage, in line with no
PDGFB detection. Conversely, the KIT gene product did not seem to play a relevant role. These findings, in the absence of activating mutations or an abnormal genomic profile and the presence of PDGFA and
PDGFB expression, are consistent with an autocrine/paracrine loop activation of the corresponding receptors. The CCS gene profile described here offers a rationale for the use of RTK inhibitors alone or in combination with
chemotherapy, and supports further investigation of RTKs and their downstream signals.