Immune recognition of human colonic‐tumour‐associated muc‐2 mucins using an anti‐peptide antibody

Abstract

In human intestinal malignancy, alterations occur in the expression of mucins defined by the MUC-2 gene. These changes include the unmasking of epitopes in the mucin protein core. In order to probe these modifications associated with mucins of the malignant phenotype, a monoclonal antibody (MAb) was developed against synthetic peptide with a sequence based upon that of the protein core of the MUC-2 mucin. The antibody (designated 996) was shown to recognize a high-molecular-weight glycoprotein from colonic carcinoma tissue. The material reacted uniformly with Concanavalin A but variably with other lectins, indicating heterogeneity in the associated oligosaccharide side chains. The protein core was accessible both to 996 antibody binding and to degradation with proteases. Immunization with the affinity-purified mucin-like material elicited antibodies reactive with both the immunogen and the synthetic peptides, confirming the immunogenic character of protein-core determinants. Epitope mapping studies, using synthetic peptides in solution and synthetic peptides tethered to the heads of plastic pins, indicated that the minimum epitope for the 996 antibody is a tetramer of T G T Q. Antibody interaction with the glutamine (Q) residue was determined to be of major importance in the antigen-antibody reaction. The findings illustrate the characterization of an anti-peptide antibody which may be used to probe alterations in MUC-2 mucin expression associated with human intestinal malignant disease.

Mucin Macromolecules in Normal, Adenomatous, and Carcinomatous Colon: Evidence for the Neotransformation

“…However, malignant transformation usually alters this. [131][132][133][134][135][136][137][138][139][140][141][142][143][144][145][146] Alterations in expression of mucin carbohydrate or peptide antigens or both are progressively described in carcinomas developed from various tissues such as breast, [147,148] endometrium, [149] ovary, [150,151] pharynx and larynx, [152] lung, [153] stomach, [154,155] liver, [156] gall bladder, [157,158] pancreas, [159,160] and small and large intestine. [161][162][163] Some mucins are rarely expressed in normal tissues, but are anomalously expressed in tumoural tissues.…”

“…[25,[40][41][42][43][44]50,54,133,[136][137][138][139][140][141][142][143][144][145] From a medical point of view, these studies are particularly important for potential diagnostics or therapeutic consequences. [54,133,142,146] This section will serve to review the biochemical and biophysical alterations of MUC2 as a predominant colonic mucin, occurring during the malignant transformation of benign adenoma to colorectal carcinoma by using an in vitro adenoma-carcinoma sequence. A multitude of scientific and clinical questions can be studied with in vitro model systems that will provide groundwork for studies ranging from the search for diagnostic molecular markers and the testing of potential anti-cancer reagents in vitro to the introduction of specific normal genes implicated in growth control into cancer cells to determine whether they can reverse the malignant phenotype, and if so by which mechanisms.…”

Expression of MUC1 and MUC2 mucins in epithelial ovarian tumours

“…12,13 Preliminary studies using anti-MUC2 core protein reactive MAbs and polyclonal antibodies showed the presence of MUC2 in tumours of the lung, breast, bladder, and ovary by immunohistochemistry. 11,[14][15][16][17][18] Previously we have shown that the presence of MUC2 correlated with a shorter disease-free interval in breast cancer patients. 17 Mucin expression by ovarian cancers has not been studied in detail.…”

Partial d -amino acid substitution: Improved enzymatic stability and preserved Ab recognition of a MUC2 epitope peptide

“…Peptides representing epitope(s) of the protein core, if attached to carrier, or their analogues (e.g., D-amino acid substituted versions) could also be considered as synthetic vaccines in active specific immunotherapy to stimulate the B cell-specific immune responses of patients with MUC2 related disease (e.g., colon carcinoma). We have identified (18,19) (20) by using protein core-specific mAb 996 (21). We have also demonstrated that the N-terminal part of peptide 16 PTPT-GTQ 22 forms ␤-turn secondary structure required for the Ab binding (22).…”

“…Peptides representing epitope(s) of the protein core, if attached to carrier, or their analogues (e.g., D-amino acid substituted versions) could also be considered as synthetic vaccines in active specific immunotherapy to stimulate the B cell-specific immune responses of patients with MUC2 related disease (e.g., colon carcinoma). We have identified (18,19) The aim of this study is to create peptides that are stable toward proteolysis and display the same, if not enhanced, binding properties compared to the original all-L peptides. Therefore, we have studied the antigenic properties and enzymatic stability of several MUC2 peptides partially substituted by D-amino acids in the flanking regions only.…”