Characterization of cluster 13: the epithelial/carcinoma antigen recognized by MAb RS7.
Cluster 13 was defined by 2 independently derived murine monoclonal antibodies (MAbs), RS7 (IgG1) and MR54 (IgG2a), which were raised against human squamous-cell carcinoma of the lung and a human ovarian-carcinoma cell line, respectively. Immunologic and biochemical evidence demonstrated that RS7 and MR54, as well as 2 additional MAbs, MR6 (IgG2a) and MR23 (IgG1), generated in the same fusion as MR54, recognize the same antigen, a 46- to 48-kDa glycoprotein. Evaluation of the expression of antigen on the surface of tumor cell lines, Western blotting analyses, competitive binding studies, and double-determinant ELISA assays, support this conclusion. Two distinct epitopes are defined by these MAbs. In order to further characterize this antigen, amino-acid-sequence analyses were performed on peptides derived from antigen purified by affinity chromatography with MAb RS7. The sequence data obtained from 2 peptides, which were independently generated by CNBr cleavage and trypsin digestion respectively indicated identity to GA733-1. The GA733-1 genomic DNA sequence predicted a type-1 membrane protein of 35 kDa, with 4 potential N-linked glycosylation sites. The GA733-1 protein product has not been identified previously, and MAbs to this tumor-associated antigen were not previously known.
Stein
R
R
Garden State Cancer Center, Center for Molecular Medicine and Immunology, Newark, NJ 07103.
Basu
A
A
Goldenberg
D M
DM
Lloyd
K O
KO
Mattes
M J
MJ
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm / Q000032:analysis* / Q000737:chemistry* / Q000235:genetics; D015153:Blotting, Western; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D015815:Cell Adhesion Molecules / Q000235:genetics; D002460:Cell Line; D004815:Epidermal Growth Factor / Q000737:chemistry; D000071858:Epithelial Cell Adhesion Molecule; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000145:classification / Q000276:immunology; D008175:Lung Neoplasms / Q000473:pathology*; D051379:Mice / Q000276:immunology; D008969:Molecular Sequence Data; D005810:Multigene Family; D009369:Neoplasms / Q000473:pathology; D010051:Ovarian Neoplasms / Q000473:pathology; D017386:Sequence Homology, Amino Acid; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D015815:Cell Adhesion Molecules; D000071858:Epithelial Cell Adhesion Molecule; D007074:Immunoglobulin G; D004815:Epidermal Growth Factor