Patients with metastatic cancer commonly have increased serum galectin-3 concentrations, but it is not known whether this has any functional implications for cancer progression. We report that MUC1, a large transmembrane mucin protein that is overexpressed and aberrantly glycosylated in epithelial cancer, is a natural ligand for galectin-3. Recombinant galectin-3 at concentrations (0.2-1.0 g/ml) similar to those found in the sera of patients with metastatic cancer increased adhesion of MUC1-expressing human breast ( Galectin-3 is one of 15 known members of the galectin family of naturally occurring galactoside-binding lectins that are expressed intracellularly and extracellularly by many cell types (1). Galectin-3 concentrations are increased up to 5-fold in the sera of patients with breast, gastrointestinal, or lung cancer (2). Moreover, higher galectin-3 concentrations are seen in the sera of patients with metastatic disease than in the sera of patients with localized tumors (2). The source of increased circulating galectin-3 in cancer patients is not clear, but it is probably generated by tumor cells as well as by peritumoral inflammatory and stromal cells (2). It is not known whether this increased circulating galectin-3 has any functional implications for cancer progression.Cytoplasmic galectin-3 is known to be anti-apoptotic (3), whereas nuclear galectin-3 promotes pre-mRNA splicing (4, 5). Cell surface galectin-3 is involved in various cell-cell and cellmatrix interactions (1, 6, 7) and enhances cancer cell adhesion to and invasion through basement membrane by interacting with extracellular matrix proteins such as fibronectin, collagen, or laminin (1,8,9). Galectin-3 expressed on the endothelial cell surface has been shown to promote the adhesion of breast cancer cells to endothelium by interaction with cancer-associated Thomsen-Friedenreich (galactose ␤1,3N-acetylgalactosamine ␣Ϫ (TF)) 2 antigen expressed by unknown cell surface molecules (10 -14). TF antigen is the core I structure of mucin-type O-linked glycans, but in its simplest nonsialylated, nonextended form it acts as an oncofetal antigen, and its presence/expression is increased in malignant and premalignant epithelia (15).MUC1 (also known as episialin and DF3) is a large (M r Ͼ 250,000) transmembrane mucin protein expressed on the apical surface of most normal secretory epithelia including those in the mammary gland, and the gastrointestinal, respiratory, urinary, and reproductive tracts. The MUC1 extracellular domain consists of variable numbers of 20-amino acid tandem repeat peptides (VNTR) that are rich in serines, threonines, and prolines. These tandem repeat domains are heavily glycosylated

Expression of the E-cadherin-catenin cell adhesion complex in primary squamous cell carcinomas of the head and neck and their nodal metastases NA Andrews1l23, AS Jones1, TR Helliwell3 and AR Kinsella2Departments of 1Otorhinolaryngology, 2Surgery and 3Pathology, University of Liverpool, Liverpool, UK Summary Reductions in cell-cell adhesion and stromal and vascular invasion are essential steps in the progression from localized malignancy to metastatic disease. In this study, changes in the expression of the components of the E-cadherin-catenin cell adhesion complex have been investigated using immunohistochemical techniques in primary tumours and nodal metastases from 36 patients with squamous cell carcinoma of the head and neck. For 14 patients the corresponding primary and nodal metastases samples were available. None of the 51 samples showed normal E-cadherin expression when compared with either the adjacent normal squamous epithelium or with normal colonic epithelium that was used as positive control material. In 88% of primary tumours fewer than 50% of cells exhibited normal membranous E-cadherin expression. Loss of membranous E-cadherin expression was more extensive in poorly differentiated carcinomas while, in individual carcinomas, membranous E-cadherin expression was stronger in those parts of the neoplasm that expressed the differentiation marker involucrin. Expression of P-catenin generally paralleled that of E-cadherin, but in 12 cases there was strong membranous P-catenin expression in samples that exhibited predominantly cytoplasmic E-cadherin labelling. Expression of a-catenin was generally weak and did not correlate with the expression of either P-catenin or E-cadherin. Marked intratumoral heterogeneity for protein expression was evident for all antibodies, and the abnormal expression of the catenins is a novel finding. E-cadherin is expressed more intensely in cells with greater squamous differentiation, but there was no correlation between the decreased expression of any of the adhesion molecules of the E-cadherin complex tested and local recurrence, metastasis or survival. The loss of expression of components of the E-cadherin complex is a common abnormality in squamous carcinomas and, while it may be permissive for metastasis, it does not appear to be the only determinant of this process.

Increased cell surface expression of the oncofetal ThomsenFriedenreich antigen (TF, Galpl-3GalNAc-) is common in malignant and hyperplastic epithelia. Our previous studies haveshown that a TF antigen-binding lectin from the common edible mushroom Agaricus bisporus (ABL) reversibly inhibits epithelial cell proliferation (Cancer Res.1993,53:4627) in association with inhibition of nuclear localization sequence (NLS)-dependent nuclear protein import (J.Biol.Chem.l999,274:4890). The purpose of this study is to investigate how ABL produces such an unique effect on nuclear protein import. Using ABL-affinity purification, an ABL-binding 16OkDa protein was obtained from the HT29 cell cytosol extracts. N-terminal protein sequencing identified the protein as an N-terminal truncated form of the oxygen-regulated protein150 (Orp150) which lacks the ER translocation signal peptide of full length Orp150. This protein expresses sialyl-TF antigen as determined by specific sialidase/OGlyganase treatment and IectinNlrestern blotting. Introduction of an anti-Grpl50 antibody to the digitonin semi-permeabilized nuclear transport system or depletion of Orp150 inhibited the nuclear accumulation of an NLS-peptide complex. This is probably the first demonstration of an intracellular glycoprotein expressing sialyl-TF. The inhibition of nuclear accumulation of NLS-complex by anti-0rp150 antibody suggests that Orp150 is required for NLS-dependent nuclear protein import. Dietary vitamin E reduces plasma and liver markers of oxidantstress in the aluminium treated rat.Aluminium (Al) toxicity may be mediated in part via reactive oxygen species (ROS). We have investigated the effects of the antioxidant vitamin E on Al-induced effects on the liver using male Wistar albino rats. A1 was administered i.p. as aluminium lactate (10 mg/Kg body weight) 5 times a week for 4 weeks. Groups (n=5 each) were either treated with aluminium alone, or with a dietary supplement of 5, 15, and 20 mg/g, of vitamin E. Further groups received 20 mg/g vitamin E supplemented diet or normal chow without Al. Following treatment, the animals were killed and, the liver and blood removed for measurement of aluminium and markers of oxidative stress. Al treatment caused a significant increase in aluminium content of plasma (P< 0.001) and liver (P< 0.001) in all groups. Liver ROS were significantly higher (P

Nuclear localization sequence-dependent nuclear protein import is essential for maintaining cell function and can be selectively blocked in epithelial cells by mushroom (Agaricus bisporus) lectin. Here we report that a major intracellular ligand for this lectin is an N-terminally truncated form of oxygen-regulated protein 150 (Orp150), which lacks the endoplasmic reticulum translocation signal peptide of full-length Orp150. This cytoplasmic form of Orp150 expresses the lectin carbohydrate ligand (sialyl-2,3-galactosyl-beta1,3-N-acetylgalactosamine-alpha) and is shown to be essential for nuclear localization sequence-dependent nuclear protein import.

No abstract