Adhesion to carcinoembryonic antigen by human colorectal carcinoma cells involves at least two epitopes

Abstract

Carcinoembryonic antigen (CEA) may be involved in both cell-cell and cell-substrate adhesion. Our purpose was to determine whether epitopes involved in the homophilic binding of human colorectal carcinoma cells to CEA participated in adhesion to basement membrane proteins. Three human colorectal adenocarcinoma cell lines and one CHO cell line transfected with CEA cDNA were tested in a solid-phase adhesion assay. The 2 CEA-expressing carcinoma cell lines (KM-12c and CCL 188) and the transfectant, but not the parental CHO line, bound to CEA. The CEA-non-producing carcinoma line (Clone A) did not bind to CEA. All colorectal carcinoma cell lines, the transfectant and the parental CHO line bound to laminin, while the colorectal carcinoma lines bound to type-IV collagen. MAbs to epitopes on CEA that cross-react with non-specific cross-reacting antigen (NCA) inhibited adhesion of CEA-expressing cells to CEA. MAbs to non-cross-reactive epitopes of CEA did not block adhesion to CEA. When the inhibitory anti-CEA antibodies were compared in a competitive radioimmunoassay, 2 distinct epitopes were identified. Epitope I is in the N-terminal domain and defined by MAbs MN3, T84.1 and C110, whereas epitope II is located in the repeating loop domains and is recognized by antibodies MN15, PR3B10 and NP1. None of the antibodies to epitope I or II blocked adhesion by KM-12c or CCL 188 cells to laminin or type-IV collagen. Thus, at least 2 different regions on CEA participate in adhesion to CEA but not to collagen or laminin by CEA-expressing human colorectal carcinoma cells.

Involvement of circulating CEA in liver metastases from colorectal cancers re-examined in a new experimental model

“…Zhou et al (1993) proposed an interaction model involving the N-terminal and A3 domains. Contribution of the N-terminal domain was confirmed by different authors but that of the A3 domain was contested (Jessup et al, 1993b;Hashino et al, 1994).…”

“…Such cells are able to form homotypic aggregates (CEA-CEA or NCA-NCA) and to a lower extent heterotypic ones (CEA-NCA) (Benchimol et al, 1989;Oikawa et al, 1989;Zhou et al, 1990). Two different CEA epitopes are presumed to be necessary for CEA-CEA interactions (Jessup et al, 1993b). Zhou et al (1993) proposed an interaction model involving the N-terminal and A3 domains.…”

Carcinoembryonic Antigen Inhibits Anoikis in Colorectal Carcinoma Cells by Interfering with Trail-R2 (DR5) Signaling

“…clone A and its stable transfectants WT CEA, delPELPK CEA, or empty vector were immunostained with MN3, a monoclonal antibody to the N-terminal domain of CEA (31), and imaged with confocal microscopy to show that delPELPK CEA is expressed on the plasma membrane of cells stably transfected with the delPELPK plasmid to the same extent as WT CEA cells (Fig. 4).…”

Opposite Functions for Two Classes of Genes of the Human Carcinoembryonic Antigen Family

“…2) and, unlike CEA, is reversibly inhibited by ATP [25], Formal similarity with the adhesion properties of the cadherins breaks down here in that cadherin-mediated adhesion is specifically dependent on Ca2+ [33], Finally, CEA-mediated adhesion has been recently shown to involve two domains [34][35][36] and, from domain studies with CEA-NCAM hybrid molecules and inhibitory pep tides, is effected by double reciprocal bonds between the N and A3B3 domains on antipa rallel molecules on apposed cell surfaces [34], Thus CEA-NCAM constructs containing the N domain or A3B3 domain alone are incapa ble of mediating homotypic adhesion in stable transfectant clones but these homotypically defective constructs are capable of mediating heterotypic adhesion when such transfectant clones are mixed. Also, bacterially produced fusion peptides representing the N terminal or A3B3 internal CEA domains can each inhibit adhesion [34], This type of bonding is unique for intermolecular binding between immuno globulin superfamily members; the predicted strength of such a mechanism could explain the fact that CEA is a potent adhesion mole cule when assessed by its ability to confer aggregation on transfectant clones [28].…”