Receptor Activator of Nuclear Transcription Factor NF-κB (RANK), Its Ligand RANKL, and Natural Inhibitor of RANKL Osteoprotegerin (OPG) in the Blood Serum of Patients with Primary Bone Tumors.

The content of components of the RANK/RANKL/OPG system, the key regulator of homeostasis in the bone tissue, in blood serum samples from 199 patients with primary bone neoplasms and 131 practically healthy volunteers was measured by ELISA. Borderline giantcell tumor of the bone with high osteoclastogenic and osteolytic activity is characterized by an increase in the level of all components of this system and highest ratio of sRANKL/OPG in the blood serum. Study indexes in patients with various benign neoplasms and tumor-like bone lesions were lower than in patients with giant-cell tumor. The patients with malignant bone tumors could be divided into 2 subgroups with opposite indexes of the RANK/RANKL/OPG system. The patients with osteosarcoma and Ewing sarcoma had a low level of sRANK, but a high level of sRANKL. The patients with chondrosarcoma and chordoma had a high level of sRANK, but a low level of sRANKL.