G. Gallardo et al., Regulation by ceramide of epidermal growth factor signal transduction and mitogenesis in cell lines overexpressing the growth factor receptor, CELL MOL B, 46(7), 2000, pp. 1305-1312
Ceramide has emerged as a pleiotropic signal mediator of cellular responses
including differentiation, proliferation, cell cycle arrest and apoptosis.
In the present study we evaluated the effect of cell permeant ceramide ana
logues on ligand-induced tyrosine phosphorylation of the EGF receptor (EGFR
), phospholipase C gamma (PLC gamma) activity and cell proliferation. Treat
ment with N-acetylsphingosine (C2-cer) and N-hexanoylceramide (C6-cer) prev
ented EGF-induced tyrosine trans-phosphorylation of the receptor in two dif
ferent cell lines overexpressing the human EGFR (A431 and EGF-T17 cells). I
n contrast, treatment of A431 and EGFR-T17 cells with C2-cer or C6-cer did
not affect the ligand binding capacity of the receptor, an effect that was
however: observed after TPA-induced activation of PKC. In addition EGF-stim
ulated PLC gamma activity was transiently decreased in A431 cells treated w
ith C6-cer and only a modest, albeit significant reduction on ligand-induce
d H-3-InsP(3) generation was observed in EGFR-T17 cells pretreated with cer
amide. We also examined the effect of C2-cer on serum (A431)- or EGF (EGFR-
T17)-induced cell proliferation Treatment of EGFR-T17 cells with C2-cer (0.
1-10 muM) did not affect cell viability, but prevented EGF-induced H-3-thym
idine incorporation in a dose-dependent manner. In contrast, H-3-thymidine
incorporation in serum-stimulated A431 cells decreased only at the higher d
oses of C2-cer used (1-10 muM), being this effect accompanied by a slight,
albeit significant (20-25%), reduction in cell viability.