Tumor promoter modulation of epidermal growth factor‐ and nerve growth factor‐induced adhesion and growth factor binding of PC‐12 pheochromocytoma cells

Abstract

Nerve growth factor (NGF) has previously been shown to increase the rate of adhesion of PC-12 pheochromocytoma cells to cell culture dishes. This increase in the rate of adhesion was postulated to be important in NGF-mediated neurite outgrowth. We now report that epidermal growth factor (EGF) is also able to increase the rate of adhesion of PC-12 cells to cell culture dishes, but does not elicit neurite outgrowth. The dose-response curve for EGF is bell-shaped, in contrast to the more classically shaped dose-response curve obtained with NGF. Tetradecanoyl-phorbol-acetate (TPA), a potent tumor promoter, blocks the EGF-induced increase in adhesion rate of PC-12 cells, but does not alter the NGF-induced increase in adhesion rate. TPA shifts the EGF bindings curve to the right for PC-12 cells, but does not alter maximal EGF binding at saturating concentrations of EGF. The binding of NGF to PC-12 cells is not affected by TPA. NGF-induced neurite formation by PC-12 cells is unaffected by TPA, in contrast to the previously reported delay of neurite outgrowth of serum-deprived neuroblastoma cells and NGF-exposed chick embryonic ganglia cells. NGF and EGF both cause a decrease in the number of short microvilli and an increase in the number of long microvilli on PC-12 cells. TPA blocks the decrease in the number of short microvilli in EGF-treated cells, but not in NGF-treated cells. Long microvilli formation is blocked by TPA in both conditions, suggesting the latter are not involved in the increased adhesion rates.

Effects of epidermal growth factor and 12-O-tetradecanoylphorbol-13-acetate on metabolism of the epidermal growth factor receptor in normal human fibroblasts.

“…Tumor promoters inhibit EGF-induced mitogenesis in human fibroblasts (34), rat hepatoma cells (29), and human hepatoma cells (37) and block EGF-induced cellular adhesion in PC12 phaeochromocytoma cells (8) and EGF-induced production of diacylglycerol in A431 cells (43). We confirm that TPA can inhibit EGF-induced mitogenesis in human fibroblasts and present a possible mechanism.…”

Comparison of rapid changes in surface morphology and coated pit formation of PC12 cells in response to nerve growth factor, epidermal growth factor, and dibutyryl cyclic AMP.

“…In addition to the alterations in surface morphology of sympathetic neurons, a threefold increase in the number of coated pits per unit area of cell surface was seen after NGF treatment (3) . In another study, PC 12 cells are reported to undergo loss ofshort microvilli and an increase in long microvilli after 1-h treatment with NGF or EGF (4) .…”

“…The first purpose of the present study was to determine whether the observed surface changes were specific manifestations of early differentiation or reflected a more universal phenomenon associated with the early response of sensitive cells to peptide growth factor treatment . To deal with this question, we chose to take advantage ofthe observation that PC12 cells have receptors for, and responses to, both NGF and EGF (4,8). These cells respond to NGF in various ways including cessation of cell division (5) and neuronal differentiation (5-7), as noted above, and respond to EGF with ornithine decarboxylase induction (8), rapid phosphorylation of several proteins (9), continued cell division, and no evident morphological differentiation (4,8) .…”

Molecular cloning of PC3, a putatively secreted protein whose mRNA is induced by nerve growth factor and depolarization.

“…Although the effect of this factor on PC12 cells is proliferative rather than differentiative, it displays several properties in common with NGF (28). When PC12 cells were treated with EGF or NGF at concentrations maximally effective in stimulating transcription of various NGF-induced genes (5 ng/ml and 100 ng/ml, respectively; ref.…”