Detection of the MUC2 apomucin tandem repeat with a mouse monoclonal antibody.

Abstract

The MUC2 intestinal mucin gene contains tandem repeats of 23 amino acid length that are rich in threonine. Mouse monoclonal antibody LDQ10 was raised against chemically deglycosylated mucin isolated from LS174T colon cancer nude mouse xenografts. LDQ10 reacts with deglycosylated colon cancer mucin and with a synthetic peptide encompassing the MUC2 tandem repeat sequence. In immunohistochemical assays, strong reactivity with goblet cells in colon, small bowel, and stomach is observed; weaker reactivity with mucin-producing cells in other epithelial tissues is shown. The epitope recognized by LDQ10 is localized in the rough endoplasmic reticulum of normal colonic goblet cells. LDQ10 also shows strong reactivity with colorectal and stomach cancers and weaker reactivity with pancreas, breast, and bladder cancers. Antibody LDQ10 detects a peptide epitope of MUC2 that becomes cryptic on glycosylation. Altered synthesis of the MUC2 apomucin takes place in a variety of epithelial cancers.