Sialylation of E-cadherin does not change the spontaneous or ET-18-OMe-mediated aggregation of MCF-7 human breast cancer cells.
We have investigated the role of sialylation on cell-cell adhesion mediated by E-cadherin. Two MCF-7 human breast cancer cell variants were studied: MCF-7/AZ cells showed a spontaneous cell-cell adhesion in the fast and slow aggregation assay. whereas the adhesion deficient MCF-7/6 cell variant failed to form larger aggregates, suggesting that E-cadherin was not functional under the conditions of both assays. We measured the sialyltransferase activities using Galbeta1-3GalNAcalpha-O-benzyl and Galbeta1-4GlcNAcalpha-O-benzyl as acceptor substrates as well as mRNA levels of four sialyltransferases, ST3Gal I, ST3Gal III, ST3Gal IV, ST6Gal I, using multiplex RT-PCR in MCF-7 cell variants. The alpha2-6 and alpha2-3 sialylation of E-cadherin was investigated by immuno-blot using Sambucus nigra agglutinin and Maackia amurensis agglutinin. Compared to the adhesion-proficient MCF-7/AZ cells, the adhesion-deficient MCF-7/6 cell line apparently lacks ST6Gal I mRNA, has a lower ST3Gal I mRNA, a lower ST3Gal I sialyltransferase activity, and no alpha2-3 linked sialic acid moieties on E-cadherin. The potential anti-cancer drug 1-O-octadecyl-2-O-methylglycero-3-phosphocholine (ET-18-OMe, 48 h, 25 microg/ml) belonging to the class of alkyllysophospholipids restored the E-cadherin function in the adhesion-deficient MCF-7/6 cells as evidenced by an increased aggregation. ET-18-OMe caused loss of ST6Gal I mRNA in MCF-7/AZ cells but no changes of sialyltransferase activities or sialic acid moieties on E-cadherin could be observed. We conclude that Ca2+-dependent, E-cadherin-specific homotypic adhesion of MCF-7/AZ or MCF-7/6 cells treated with ET-18-OMe was not affected by sialylation of E-cadherin.
Steelant
W F
WF
Department of Radiotherapy and Nuclear Medicine, University Hospital Ghent, Belgium.
Recchi
M A
MA
Noë
V T
VT
Boilly-Marer
Y
Y
Bruyneel
E A
EA
Verbert
A
A
Mareel
M M
MM
Delannoy
P
P
D000970:Antineoplastic Agents / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000201:enzymology / Q000378:metabolism / Q000473:pathology*; D015820:Cadherins / Q000378:metabolism*; D002449:Cell Aggregation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D005260:Female; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D010742:Phospholipid Ethers / Q000494:pharmacology*; D011233:Precipitin Tests; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012794:Sialic Acids / Q000378:metabolism*; D012799:Sialyltransferases / Q000096:biosynthesis / Q000378:metabolism; D014407:Tumor Cells, Cultured
D000970:Antineoplastic Agents; D015820:Cadherins; D006023:Glycoproteins; D010726:Phosphodiesterase Inhibitors; D010742:Phospholipid Ethers; D012794:Sialic Acids; C026659:edelfosine; D012799:Sialyltransferases