Localization of human breast tumors grafted in nude mice with a monoclonal antibody directed against a defined cell surface antigen of human mammary epithelial cells

Epitope expression on the breast epithelial mucin

Multiple epitope expression on the breast epithelial mucin was explored using a panel of monoclonal antibodies (MoAbs) created against milk and breast tissue preparations, against blood group determinants, and against other non-breast epithelial mucins. Since the breast epithelial mucin is now used in both diagnostic and therapeutic modalities for breast cancer, and also because altered or incomplete glycosylation in varying degrees is expected in breast carcinoma tissue, the antigenic target used here was the native mucin and sequential stages of deglycosylation introduced to it by HF treatment. Partial deglycosylation increased exposure of core peptide amino acid sequences increasing MoAb binding generally, while it either decreased or occasionally increased binding of blood group oligosaccharides. Cross reactivity of MoAbs to other mucins was low with the breast epithelial mucin (BEM). The study of the affinity binding constants of some of the anti-BEM peptide MoAbs predicted carbohydrate participation in their epitope structure. The identification of different epitopes on the BEM, investigations on their possible epitopic structure, and the study of MoAb binding during different stages of glycosylation of the molecule leads to knowledge on the contribution of carbohydrates to their epitopes and strengthens the ability to understand their performance in their diverse possible applications in breast cancer diagnosis, prognosis, and therapy.

Effect of dietary fat and monoclonal antibody therapy on the growth of human mammary adenocarcinoma MX-1 grafted in athymic mice

A diet containing 11% per weight fish oils (Max-EPA) reduced the rate of growth of a transplantable human breast tumor (MX-1) grafted into immunodeficient mice (BALB/c, nu/nu) when compared to MX-1 tumors in mice fed polyunsaturated (corn oil) and saturated (lard) fatty acids; however, there was no difference between the corn oil and lard animal groups. Treatment with a cocktail of monoclonal antibodies (MoAbs) decreased the rat of growth of MX-1 in the corn oil fed animals but not in those fed lard or Max-EPA, but the rate of tumor growth of the Max-EPA treated group, either MoAb treated or not, was slower than that of the corn oil and lard groups.

Human milk-fat globule membrane derived mucin is a disulfide-linked heteromer

The human milk-fat globule membrane (HMFG) contains a number of antigens also expressed on breast tumors. The dominant antigens are a mucin of MW greater than 400,000 and a group of antigens of MW 67,000-70,000. The mucin was separated with monoclonal antibodies against HMFG and a MW 70,000 doublet was found to be associated with the mucin under non-reducing conditions, the latter identifiable by another set of monoclonal antibodies. Immunoprecipitation of the mucin and analysis of the precipitated material using Western blots and identification of transferred material with monoclonal antibodies demonstrated that the MW 70,000 protein and the mucin were co-precipitated and linked by reducible disulfide bonds. Treatment with detergents, protein-dissociating agents and glycosidases did not release the component from the mucin. Mucins in HMFG membrane and breast tumor cells may be associated therefore to disulfide-linked linker proteins similar to those described for intestinal and gastric mucins, that would co-purify with the mucin under non-reducing conditions.