CELL-ADHESION MOLECULES AND INTERMEDIATE FILAMENTS ON EMBRYONAL CHILDHOOD TUMORS

We describe the expression of is different cell adhesion molecules, in termediate filaments and Ki-67 antigen in embryonal childhood tumors. 5 mu m frozen sections from 15 nephroblastomas, 13 neuroblastomas, six rhabdomyosarcomas, one Ewing sarcoma and one pulmonary blastoma were analyzed by the alkaline phosphatase anti-alkaline phosphatase (APAAP) method using murine monoclonal antibodies. All tumors exhibited high proliferation rates as did, surprisingly, the nephroblastoma specimens despite pre-treatment with chemotherapy. Polysialylated NCAM was demo nstrated on all tumor types, but Ewing sarcoma and expression correlat ed inversely with cell differentiation. In contrast, E-cadherin was pr esent solely on tubulus like cells in nephroblastomas. This cell type showed a coexpression of cytokeratin and vimentin, giving evidence of its intermediate position between the mesenchyme and epithelium. In ne uroblastomas, CD44s (hyaluronate receptor) expression was increased wi th cell differentiation. ICAM-1, VCAM-1 and E-selectin were mostly exp ressed in regressive areas of pretreated nephroblastoma specimens wher e a considerable infiltration of leukocytes was noted as well. Since e ndothelial and leukocyte adhesion molecules were distinctly less expre ssed in all other tumors investigated, these findings may indicate imm unological processes as a consequence of or as supplement to the chemo therapeutical effect on nephroblastoma cells. Integrin receptors were not found on the surface of tumor cells, and therefore, at least, thos e investigated seem to be of secondary importance to the biology of th e tumors studied herein. In conclusion, our investigations demonstrate that, besides achieving a secure and prompt differentiation between v arious embryonal tumors, applying the panel of monoclonal antibodies p roposed herein gives interesting insights into the histogenesis, biolo gy and metastatic potential of pediatric malignancies.