OSTEOSARCOMA - APOPTOSIS AND PROLIFERATIO N

The relationsship between the growth of tumors and the expression of t he protooncogen Bcl-2 could be shown in epithelial tumors. A bcl-2 exp ression leads to a prolonged cell survival due to an inhibition of apo ptosis. The potential meaning of bcl-2 expression in mesenchymal tumor s remains still unknown. The fact, that the heterogenous group of oste osarkoma is not sufficiently characterized at present, suggested to in vestigate the bcI-2 expression in osteosarcoma. Thus, immunohistochemi stry was used to analyze 47 specimens of different osteosarcomas of 36 patients. Sixteen cases (46%) showed a strong expression of bcl-2 and 13 cases (35%) were moderately positiv for bcl-2. Seven cases (19%) w ere negative for bcl-2. The heterogenous, negative up to strong expres sion of bcl-2 yield clues, that the Bcl-2 controlled regulation of pro grammed cell death could be an important factor of cellular kinetics. Additionally the cellular proliferationrate was determined with the mo noklonal antibody MIB 1, directed against the Ki-67 epitop. The data o f bcl-2 expression and cellular proliferationrate lead to a classifica tion correlating with the histological classification. To verify the i mportance of apoptosis in the genesis of mesenchymal tumors and whethe r Bcl-2 may play an important role as a predictive factor for the prog nosis of osteosarcoma, further investigations will be needed.