Transactivation of E-cadherin is not involved in the activity of EGF receptor in colorectal carcinoma cells.
In epithelial cells, the cell surface glycoprotein E-cadherin is a key molecule in the establishment of cell-cell adhesion. In addition to its contribution to cell adhesion, E-cadherin was found to induce ligand-independent activation of the EGF receptor (EGFR), likely as a result of their co-clustering. As it has also been reported that ligand activation of the overexpressed EGFRs disturb E-cadherin-mediated cell-cell adhesion, we analyzed E-cadherin-EGFR interactions and their consequences in A431 cells and in two colorectal cancer cell lines using immunoblotting and analyzes of several protein kinase activities. Activation of the PI3-K/Akt/GSK-3 signaling pathway upon EGF treatment that we observed in the analyzed cells indicates that EGFRs are functional even in the colorectal cancer cells containing a low density of EGFRs. The transactivation of EGFR by E-cadherin did not occur either in the colorectal cancer cells tested or in A431 cells containing a high density of both EGFRs and E-cadherin on their surface. This observation suggests that high amounts of both molecules on the surface of tumour cells did not predetermine ligand-independent activation of EGFRs.
Sovová
Vlasta
V
Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 37 Prague 6, Czech Republic. sova@img.cas.cz
Kucerová
Dana
D
Vojtechová
Martina
M
Sloncová
Eva
E
Tuhácková
Zdena
Z
D015820:Cadherins / Q000096:biosynthesis* / Q000494:pharmacology; D002277:Carcinoma / Q000235:genetics* / Q000473:pathology*; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology*; D066246:ErbB Receptors / Q000096:biosynthesis*; D006801:Humans; D015151:Immunoblotting; D008024:Ligands; D015398:Signal Transduction; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured
D015820:Cadherins; D008024:Ligands; D066246:ErbB Receptors