ANALYSIS OF THE PRESENCE OF OSTEOCALCIN, S-100 PROTEIN, AND PROLIFERATING CELL NUCLEAR ANTIGEN IN CELLS OF VARIOUS TYPES OF OSTEOSARCOMAS

Osteosarcomas are characterized by different histologic subtypes that are composed of heterogeneous tumor cells. Although the histological o rigin of the malignant cells is unknown, it has been speculated that o steoblasts lead to the malignant cells. In the current study, the oste osarcoma cells in 27 lesions were assessed by means of immunohistochem ical staining for osteocalcin (OC), S-100 protein (S-100) and prolifer ating cell nuclear antigen (PCNA). PCNA labeling indices were the high est in osteoblastic and stromal areas, and significantly lower in chon droblastic areas (p<0.01). Cells that were positive for both PCNA and OC were abundant in osteoblastic and stromal areas, while cells that w ere positive for both PCNA and S-100 were rarely observed. These resul ts were almost similar for conventional, parosteal and periosteal oste osarcomas. In contrast, OC reactivity was poor in fibroblastic osteosa rcoma, in osteosarcoma with giant cells, and in telangiectatic osteosa rcoma. Pulmonary metastatic osteosarcoma lesions weakly expressed OC ( p<0.01), but showed high values for the PCNA labeling indices. In conc lusion, immunohistochemical staining for OC, S-100, and PCNA are usefu l to analyze the proliferating cells in osteosarcomas. The main prolif erating cells in most osteosarcomas are mature osteoblast-like cells. OC-negative tumor cells predominate in some of osteosarcoma subtypes, and these tumors therefore probably represent a distinct osteosarcoma variant. OC expression in pulmonary metastatic lesions may be suppress ed.