Sialylation of E-cadherin does not change the spontaneous or ET-18-OMe-mediated aggregation of MCF-7 human breast cancer cells

• Published in: Clinical & experimental metastasis 1999-05, Vol.17 (3), p.245-253
• Main Authors: Steelant, W F, Recchi, M A, Noë, V T, Boilly-Marer, Y, Bruyneel, E A, Verbert, A, Mareel, M M, Delannoy, P
• Format: Article
• Language: English
• Subjects: Antineoplastic Agents - pharmacology; Breast Neoplasms - enzymology; Breast Neoplasms - metabolism; Breast Neoplasms - pathology; Cadherins - metabolism; Cell Aggregation - drug effects; Cell Survival - drug effects; Female; Glycoproteins - metabolism; Humans; Immunoblotting; Phosphodiesterase Inhibitors - pharmacology; Phospholipid Ethers - pharmacology; Precipitin Tests; Reverse Transcriptase Polymerase Chain Reaction; Sialic Acids - metabolism; Sialyltransferases - biosynthesis; Sialyltransferases - metabolism; Tumor Cells, Cultured
• ISSN: 0262-0898; 1573-7276
• DOI: 10.1023/A:1006639804430

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.