Cell surface alterations on colon adenocarcinoma cells

By the use of five independent techniques, cell surface alterations distinctive of malignant as compared to normal colon cells were detected on in vivo surgical specimens and on cultured cell lines established in our laboratory. The findings, which were distinctive of the malignant as compared to the normal cell included: (a) polymorphism of surface microvilli on scan electron microscopy; (b) decreased susceptibility to infection with vaccinia and reovirus, but not to herpes, adeno- or echovirus: (c) production of large quantities of carcinoembryonic antigen; (d) presence of specific membrane proteins on sodium dodecyl sulfate-polyacrylamide gel analysis of plasma membranes purified from cell homogenates by ultracentrifugation in polyethylene glycol-dextran partitions; and (e) reaction with specific, cytotoxic, rabbit heteroantisera. Solubilized extracts of the malignant cells formed precipitin lines with the heteroantisera, suggesting that the distinctive antigens could be released from the cell surface. These results suggest that human colon carcinomas bear tumor-distinctive proteins and offer the prospect of specific immunodiagnostic reagents and immunotherapeutic tools.