Analysis of a human osteogenic sarcoma antigen and its expression on various human tumour cell lines

✍ Scribed by D. G. Campbell; Dr. M. R. Price; R. W. Baldwin

• Publisher: John Wiley and Sons
• Year: 1984
• Tongue: French
• Weight: 839 KB
• Volume: 34
• Category: Article
• ISSN: 0020-7136
• DOI: 10.1002/ijc.2910340107

✦ Synopsis

Abstract

The murine monoclonal antibody 79IT/36 cross‐reacts with cells other than the immunizing osteogenic sarcoma cell line 79IT, upon which the 79IT/36‐defined epitope is expressed on a protein of apparent molecular weight 72,000. An investigation was performed to determine whether the epitope occurred on similar molecules on other cell lines. Radiolabelled immunoprecipitates, prepared with the 79IT/36 antibody, from three osteogenic sarcoma cell lines (2 OS, 788T and 278T), the prostate carcinoma EB33 and the colon carcinoma HcLo each contained a protein with a molecular weight of 72,000 as the major constituent, together with, in some cases, material of lower molecular weight. This heterogeneity was shown by neuraminidase treatment of the immune precipitates to be due to variations in sialic acid content of the antigens since, in five of the six cell lines tested, such treatment produced homogeneous material of apparent molecular weight 55,000. Chymotrypsin treatment of the immune precipitates produced in each instance a major polyypeptide of molecular weight 47,000 which displayed no microheterogeneity. Immunoadsorbent‐purified antigen from 79IT cells was shown to bind strongly to Sepharose‐wheat‐germ agglutinin and less to Sepharose‐concanavalin A, confirming the glycoprotein nature of this antigen. These studies demonstrate that molecules expressing the 79IT/36‐defined epitopes on different tumour cell lines are glycoproteins which display heterogeneity with respect to apparent molecular weight that is attributable to varying degrees of sialylation. No apparent differences were detected in the polypeptide “backbone” of these antigenic molecules.