Study of the expression of Tn antigen in different types of human breast cancer cells using VVA-B4 lectin.

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.

Leptin: a proliferative factor for breast cancer? Study on human ductal carcinoma.

Mammary adipose tissue is an important source of paracrine mitogens and anti-mitogens, including insulin-like growth factor, transforming growth factors, and cytokines (especially, TNFalpha and IL-1beta). Nevertheless, it is also an important source of the adipocytokine, leptin. Recently, leptin was reported to stimulate the proliferation of various cell types (pancreatic beta cells, prostate, colorectal, lung, etc.) as a new growth factor. It was also shown to stimulate the proliferation of breast cancer cell lines. In this study, we conducted an immunohistochemical analysis of leptin expression in normal tissue and benign and malignant ductal breast cell, representing the different states of the invasion process. We determined for the first time that leptin is expressed both by ductal breast tumors and by benign lesions as atypical hyperplasia. This suggests that leptin may be taken up or synthesized by all modified ductal breast cells, and may prove a proliferative factor. Moreover, leptin is unexpressed by normal tissue in the healthy breast but is exhibited by the normal tissue in near vicinity of the malignant ductal breast lesions. We also postulated that leptin may be a prognostic or diagnostic factor for ductal breast cancer. These putative hypotheses require further study.

Ultrastructural localization of binding sites for PNA and VVA-B(4) lectins in human breast cancer cell lines detected by confocal fluorescence microscopy.

Three cancer cell lines (MCF-7, HBL-100, MDA-MB 231) and subnormal breast epithelial cell line MCF-10A were labeled with FITC-conjugated VVA-B4 lectin, specific for D-GalNAcalpha-O-ser/thr, matching the structure of Tn antigen sugar residues, and with RTIC-conjugated PNA lectin, specific for DGalbeta1-3GalNAc-O-ser/thr, corresponding to the structure of T antigen. Simultaneous expression of Tn and T antigens on the same cells (but in widely differing proportions) led to their large heterogeneity and occurrence of numerous cell subpopulations within each of the studied cell lines. This observation proved that the changes leading to the formation of Tn antigen are not caused by an irreversible genetic mutation of beta1-3-galactosyltransferase. Expression of Tn antigen on MCF-10A cells with normal (or subnormal) karyotype suggests that the process of malignant transformation of the cell begins with the changes in molecular structure of glycoconjugates.

In vitro cultures of higher plants and fungi as a potential source of bioactive metabolites.

The review presents the results of investigations conducted at the Chair of Pharmaceutical Botany, Collegium Medicum, Jagiellonian University, which demonstrated a prospects to obtain biologically active metabolites representative of many chemical groups (furanocoumarins, polysaccharides and lectins, indole compounds, carotenoids) in in vitro cultures of both higher plants and higher fungi (Macromycetes) (mycelial cultures). These cultures can be a potential, rich, new source of metabolites.

Purification and characterization of an anti-(A+B) specific lectin from the mushroom Hygrophorus hypothejus.

A lectin (HHL) was isolated from the fruiting body of the mushroom Hygrophorus hypothejus by a combination of affinity chromatography on stromas of group B erythrocytes embedded in polyacrylamide gel, and DEAE-trisacryl and gel filtration chromatography. Its molecular mass, as determined by gel filtration, is estimated to be 68000 kDa and its structure is tetrameric with four identical subunits assembled with non-covalent bonds. HHL agglutinates specifically A and B blood group erythrocytes and in hemagglutination inhibition assays, exhibits sugar-binding specificity toward lactose, the anomeric alpha form being more effective than the beta form.

[Expression of T and Tn antigens in breast cancers]. / Expression des antigènes T et Tn dans les cancers du sein.

Expression of carcinoembryonic Tn antigen studied with VVA-B4 and GSI-A4 lectins with the monoclonal antibody 83D4 and of T antigen with LDL and PNA lectins with the monoclonal antibody ZCMO4, were examined in 54 malignant or benign human breast tumors and for MCF-7, T47D and MCF-10A cell lines of human breast tumors origin. For breast tissues, positive membrane labelling with D-GalNAc alpha-O-ser/thr (Tn-antigen) specific lectins and 83D4 MAb occurred in benign cases indicating that modification of glycoconjugates may precede the cytologic anomalies. In fibroadenoma, fibrocystic dystrophy, ductal hyperplasia and grade I invasive ductal carcinomas, the binding sites for lectins and 83D4 MAb were essentially on the cell membrane with labelling of both apical and basolateral compartments. In grade II and III, the labelling involved the cytoplasma, and cell heterogeneity appeared. The disappearance of reactivity observed for a large proportion of cells at grade III may be due either to the loss of glycosyltransferase, or to the lack of synthesis of the protein back-bone. Invasive lobular carcinomas showed labelling both on apical membrane and the outermost part of the cytoplasm with a distinct cell polarity. Lectin receptors are present at the surface of metastatic cells, possibly related to their involvement in adhesion. In all cases, T or sialosyl-T antigens are present at the surface of tumors cells. All cell lines from breast tumors cultured in vitro were labelled with lectins and monoclonal antibodies. The simultaneous presence of Tn and T antigens on the cells, indicates that the expression of Tn antigen is due to a partial but non total deficiency in the beta-1- > 3 galactosyltransferase involved in T-antigen synthesis.

Expression of Tn antigen and N-acetyllactosamine residues in malignant and benign human breast tumors detected by lectins and monoclonal antibody 83D4.

Expressions of the carcinoembryonic Tn antigen studied with VVA-B4 and GSI-A4 lectins with the monoclonal antibody 83D4 and of N-acetyllactosamine residues with ECA and LSL lectins, were examined in 54 malignant or benign human breast tumors. Positive membrane labelling with lectins and 83D4 MAb occured in benign cases indicating that modification of glycoconjugates may precede the cytologic anomalies. In fibroadenoma, fibrocystic dystrophy, ductal hyperplasia and grade I invasive ductal carcinomas, the binding sites for all lectins and 83D4 MAb were essentially on the cell membrane with labelling of both apical and basolateral compartments. In grade II and III, the labelling involved the cytoplasm, and cell heterogeneity appeared. The disappearance of reactivity observed for a large proportion of cells at grade III may be due either to the loss of glycosyl-transferase, or to the lack of synthesis of the protein back-bone. Invasive lobular carcinomas showed labelling both on apical membrane and the outermost part of the cytoplasm with a distinct cell polarity. Lectin receptors are present at the surface of metastatic cells, possibly related to their involvement in adhesion.

Isolation and characterization of an N-acetyllactosamine-binding lectin from the mushroom Laetiporus sulfureus.

A hemagglutinating and hemolytic lectin (PSL) has been isolated from carpophores of the parasitic mushroom Laetiporus sulfureus by affinity chromatography on Sepharose. Its molecular weight, as determined both by gel filtration and by electrophoresis in non-denaturing conditions, is about 190,000 and its structure is tetrameric, with two distinct types of subunits (about 60,000 and 36,000). It appeared homogeneous on HPLC gel filtration but exhibited microheterogeneity on isoelectric focusing. Hapten inhibition assay indicated that the Laetiporus lectin is specific for N-acetyllactosamine residues and that hemagglutinating and hemolysis activities are supported by the same site.