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.
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 beta-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.
Steelant
W F
WF
Laboratory of Experimental Cancerology, Ghent University Hospital, Gent, Belgium.
Goeman
J L
JL
Philippé
J
J
Oomen
L C
LC
Hilkens
J
J
Krzewinski-Recchi
M A
MA
Huet
G
G
Van der Eycken
J
J
Delannoy
P
P
Bruyneel
E A
EA
Mareel
M M
MM
D000911:Antibodies, Monoclonal / Q000378:metabolism; D019921:Biotinylation; D015152:Blotting, Northern; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000473:pathology*; D015820:Cadherins / Q000378:metabolism*; D002448:Cell Adhesion; D002449:Cell Aggregation; D002462:Cell Membrane / Q000378:metabolism; D002470:Cell Survival; D003094:Collagen / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005434:Flow Cytometry; D006801:Humans; D015151:Immunoblotting; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D018396:Mucin-1 / Q000096:biosynthesis / Q000378:metabolism / Q000494:pharmacology*; D009361:Neoplasm Invasiveness; D010641:Phenotype; D010713:Phosphatidylcholines / Q000494:pharmacology*; D010742:Phospholipid Ethers; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D011863:Radioimmunoassay; D015398:Signal Transduction; D013997:Time Factors; D015534:Trans-Activators; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism; D051176:beta Catenin
D000911:Antibodies, Monoclonal; C495270:CTNNB1 protein, human; D015820:Cadherins; D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors; D018396:Mucin-1; D010713:Phosphatidylcholines; D010742:Phospholipid Ethers; D015534:Trans-Activators; D051176:beta Catenin; C026659:edelfosine; D014443:Tyrosine; D003094:Collagen