Cell adhesion molecules and intermediate filaments on embryonal childhood tumors

We describe the expression of 18 different cell adhesion molecules, intermediate filaments and Ki-67 antigen in embryonal childhood tumors. 5 microns 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 demonstrated on all tumor types, but Ewing sarcoma and expression correlated inversely with cell differentiation. In contrast, E-cadherin was present 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 neuroblastomas, CD44s (hyaluronate receptor) expression was increased with cell differentiation. ICAM-1, VCAM-1 and E-selectin were mostly expressed in regressive areas of pretreated nephroblastoma specimens where a considerable infiltration of leukocytes was noted as well. Since endothelial and leukocyte adhesion molecules were distinctly less expressed in all other tumors investigated, these findings may indicate immunological processes as a consequence of or as supplement to the chemotherapeutical effect on nephroblastoma cells. Integrin receptors were not found on the surface of tumor cells, and therefore, at least those investigated seem to be of secondary importance to the biology of the tumors studied herein. In conclusion, our investigations demonstrate that, besides achieving a secure and prompt differentiation between various embryonal tumors, applying the panel of monoclonal antibodies proposed herein gives interesting insights into the histogenesis, biology and metastatic potential of pediatric malignancies.