The MET receptor tyrosine kinase contributes to invasive tumour growth in rhabdomyosarcomas

The receptor tyrosine kinase MET and its ligand hepatocyte growth factor (HGF), have been implicated in the genesis of the paediatric tumour rhabdomyosarcoma (RMS). Addition of exogenous HGF to RH30 RMS cells enhanced non-chemotactic migration. Stable transfection of dominant negative MET into RH30 cells attenuated Matrigel invasion and in vivo tumour growth. To assess the role of a putative HGF-MET pathway in human RMS, we measured their expression in a panel of 68 human primary tumours. All tumours expressed MET but with a three orders of magnitude variation of expression and 62% of tumours co-expressed HGF. In contrast with other tumour types, neither high-MET expression nor HGF/MET coexpression correlated with metastatic disease. In a microarray screen, we identified CCN1 as being 7.8-fold up regulated following addition of HGF to RH30 cells and in RMS tumours, CCN1 expression correlated with HGF expression. Surprisingly, we identified MET as a consistent feature of embryonal and not alveolar RMS.