Identifying Mechanisms for Therapeutic Intervention in Chordoma c-Met Oncoprotein

Study Design. A human sacral chordoma cell line, CCL3, was established and in vitro characterization of c-Met oncoprotein in chordoma cells was performed. Objective. Determination of whether c-Met plays an important role in chordoma's malignancy. Summary of Background Data. Chordomas are malignant life-threatening tumors that arise from the remnants of the notochord. c-Met is an oncoprotein that is expressed by a variety of solid tumors, including chordomas, and HGF is its high affinity ligand. In the present study, we investigated c-Met and HGF expression, localization, and function in human chordoma cells. Methods. SDS-PAGE, Western blotting, immunofluorescence techniques, and cell migration functional assays were used to asses c-Met and HGF expression, localization, and functional activity. Results. Intracellular protein tyrosine phosphorylation was enhanced on HGF binding, and an increase in the amount of 50 kDa alpha-chain of c-Met was detected in HGF-stimulated cells. Immunostaining of c-Met and HGF revealed membrane/cytoplasmic localization in nonstimulated cells, and perinuclear colocalization in HGF-stimulated cells. Positive chemotactic and migration activity in response to HGF was also demonstrated. Conclusion. Our data supports our hypothesis that the c-Met oncoprotein plays a leading role in the metastatic process in chordomas, and that a c-Met-HGF pair is involved in chordoma malignancy. Taking into consideration the very limited treatment options and an extremely poor prognosis for the chordoma patients, our results are a valuable and promising addition to the current situation in managing chordomas.