Alkyl‐lysophospholipid 1‐O‐octadecyl‐2‐O‐methyl‐ glycerophosphocholine induces invasion through episialin‐mediated neutralization of E‐cadherin in human mammary MCF‐7 cells in vitro

• Published in: International journal of cancer 2001-05, Vol.92 (4), p.527-536
• Main Authors: Steelant, Wim F.A., Goeman, Jan L., Philippé, Jan, Oomen, Lauran C.J.M., Hilkens, John, Krzewinski‐Recchi, Marie‐Ange, Huet, Guillemette, Van der Eycken, Johan, Delannoy, Philippe, Bruyneel, Erik A., Mareel, Marc M.
• Format: Article
• Language: English
• Subjects: 2-lysophosphatidylcholine; adhesion; alkyl‐lysophospholipid; Antibodies, Monoclonal - metabolism; beta Catenin; Biological and medical sciences; Biotinylation; Blotting, Northern; Blotting, Western; Breast Neoplasms - pathology; Cadherins - metabolism; Cell Adhesion; Cell Aggregation; Cell Membrane - metabolism; Cell Survival; Collagen - metabolism; Cytoskeletal Proteins - metabolism; E-cadherin; Enzyme Inhibitors - pharmacology; episialin; Flow Cytometry; Gynecology. Andrology. Obstetrics; Humans; Immunoblotting; invasion; Mammary gland diseases; Medical sciences; Microscopy, Confocal; Microscopy, Fluorescence; Mucin-1 - biosynthesis; Mucin-1 - metabolism; Mucin-1 - pharmacology; Neoplasm Invasiveness; Phenotype; Phosphatidylcholines - pharmacology; Phospholipid Ethers; Phosphorylation; Precipitin Tests; Protein Binding; Radioimmunoassay; Signal Transduction; Time Factors; Trans-Activators; Tumor Cells, Cultured; Tumors; Tyrosine - metabolism
• ISSN: 0020-7136; 1097-0215
• DOI: 10.1002/ijc.1216

1‐O‐octadecyl‐2‐O‐methyl‐glycerophosphocholine (ET‐18‐OMe) is an analogue of the naturally occurring 2‐lysophosphatidylcholine belonging to the class of antitumor lipids. Previously, we demonstrated that ET‐18‐OMe modulates cell‐cell adhesion of human breast cancer MCF‐7 cells. In the present study, we tested the effect of ET‐18‐OMe on adhesion, invasion and localisation of episialin and E‐cadherin in MCF‐7/AZ cells expressing a functional E‐cadherin/catenin complex. The MCF‐7/6 human breast cancer cells were used as negative control since their E‐cadherin/catenin complex is functional in cells grown on solid substrate but not in suspension. The function of E‐cadherin, a calcium‐dependent transmembrane cell‐cell adhesion and signal‐transducing molecule, is disturbed in invasive cancers by mutation, loss of mRNA stability, proteolytic degradation, tyrosine phosphorylation of associated proteins and large cell‐associated proteoglycans or mucin‐like molecules such as episialin. Episialin, also called MUC1, is an anti‐adhesion molecule that by its large number of glycosylated tandem repeats can sterically hinder the adhesive properties of other glycoproteins. ET‐18‐OMe inhibited the E‐cadherin functions of MCF‐7/AZ cells as measured by inhibition of fast and slow aggregation and by the induction of collagen invasion. These effects were enhanced by MB2, an antibody against E‐cadherin and blocked by monoclonal antibodies (MAbs) 214D4 or M8 against episialin. ET‐18‐OMe had no influence on tyrosine phosphorylation of β‐catenin and the E‐cadherin/catenin complex remained intact. Transcription, translation, protein turnover and cell surface localisation of episialin were not altered. ET‐18‐OMe induced finger‐like extensions with clustering of episialin together with E‐cadherin and carcinoembryonic antigen but not with occludin. In cells in suspension, ET‐18‐OMe caused a shift in the flow‐cytometric profile of episialin toward a lower intensity for MCF‐7/AZ cells. In contrast with MCF‐7/AZ cells, the adhesion‐deficient and noninvasive MCF‐7/6 cells showed neither morphotypic changes nor induction of aggregation nor invasion in collagen I upon treatment with ET‐18‐OMe. Co‐localisation of episialin with E‐cadherin was rarely observed. We conclude that in the human breast cancer cells MCF‐7/AZ, E‐cadherin and episialin are key molecular players in the regulation of promotion and suppression of cell‐cell adhesion and invasion. © 2001 Wiley‐Liss, Inc.