Expression of a high molecular weight mucin-type glycoprotein in human colon cancer as defined by monoclonal antibody 1D3

Murine monoclonal antibody 1D3 recognizes a high molecular weight acidic mucin restricted to the epithelium of normal colonic mucosa and goblet cells. Of 72 colonic carcinoma specimens examined, 29 were found to have detectable level of 1D3 antigen by an indirect immunoperoxidase staining assay on fixed, paraffin-embedded tissue sections. In some specimens a focal staining pattern was observed, while in others 50-90% of tumor cells were stained. Of 28 cases having adjacent normal mucosa, all 28 showed intense staining reaction in the normal mucosa and goblet cells despite the fact that 18 of the tumors were unstained. One of 1 colonic diverticulosis, 2 of 2 ulcerative colitis, 3 of 3 villo-glandular polyps, 19 of 20 adenomatous polyps and 17 of 19 hyperplastic polyps were also stained heavily for the 1D3 antigen. Colonic carcinomas displayed a range of staining patterns and a great degree of antigenic heterogeneity. Well-differentiated tumors characterized by typical goblet cells were almost always positive (10 of 12). As cellular structure became disorganized, as in moderately-differentiated tumors, about 33% of the tumors (17 of 51) stained for 1D3 antigen. As the tumor became more invasive with further disorientation of cellular features, as in poorly differentiated tumors, very few specimens (2 of 9) were positive. It was apparent that with the progression of de-differentiation there was a gradual loss of 1D3 antigen in human colonic tumors.