VVA-B4
lectin was used to investigate the differences in
Tn antigen expression in tissues of different types of human
breast cancer (benign lesions,
carcinoma in situ, invasive
carcinoma) and in normal tissues neighboring
lobular carcinoma. Locations in which
Tn antigen was expressed were identified using the
avidin-
biotin-
peroxidase labeling system. Tissues collected during cosmetic procedures and classified as normal were completely negative, except for one case. Benign proliferative changes including
fibroadenoma, apocrine and cylindrical
metaplasia showed a very weak positive reaction, although strongly positive cells were also observed. The reaction in non-invasive cases of atypical
hyperplasia was diversified depending on site. Intralobular
hyperplasia was characterized by a particularly high percentage of labeled cells. A majority (up to 80%) of ductal and
lobular carcinoma in situ showed very strong or moderate staining. In invasive
cancers, there were conspicuous differences between stage of
cancer development and tendency towards a decrease in intensely labeled cell count in the most advanced stages. In normal tissues in the direct neighborhood of
carcinoma in situ, the cytoplasm of 40% of cells was strongly labeled. However, the findings for normal tissues in the close vicinity of invasive
cancer were the most surprising, since there was either no or only very weak positive reaction. It can be concluded that glycosylation modifications during
carcinogenesis, as demonstrated by the presence of Tn
epitope, develop very early, before any destructive changes in proliferation/apoptosis or cell differentiation become discernible.