Circulating Candidate Biomarkers in Giant Cell Tumours of Bone.

Purpose Experimental design Approximately 5% of giant cell tumors (GCT) of bone develop pulmonary metastases. Although many biomarkers have been proposed, identification of circulating low abundance molecules may be useful to predict malignant progression. The hydrogel nanoparticle technique followed by MS was used to detect low molecular weight serum proteins or protein fragments in serum of 20 GCT patients with different clinical course and in ten healthy sera used as control. The most representative low-abundant de novo or differentially abundant proteins were submitted to String database that recognized interconnected activated pathways including protein activation cascade, wound healing, cell-substrate adhesion, and response to stress. Statistics were performed for identification of candidate prognostic factors. Results Conclusions and clinical relevance Proteome cluster analysis separated metastasis-free from metastatic GCT patients in two well-defined groups where serum levels of signaling transduction mediators and regulators of kinase activity presented a high discriminatory power. Increased expression of proteins STAT5B, GRB2, and OXSR1 was related to a higher probability of metastasis. Multivariate analysis demonstrated that tumor grade and STAT5B were independent prognostic factors. By using a noninvasive technique, we identified differentially abundant serum candidate biomarkers, also providing prognostic information in patients with GCT of bone.