bryostatin-1 and Neuroblastoma
bryostatin-1 has been researched along with Neuroblastoma* in 5 studies
Other Studies
5 other study(ies) available for bryostatin-1 and Neuroblastoma
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Bryostatin-1 vs. TPPB: dose-dependent APP processing and PKC-α, -δ, and -ε isoform activation in SH-SY5Y neuronal cells.
Activation of the α-secretase processing pathway of amyloid precursor protein (APP) is recognized as an important mechanism which diverts APP processing from production of beta-amyloid (Aβ) to non toxic sAPPα, decreasing Alzheimer's disease (AD) plaque formation and AD-associated cognitive deficits. Two potent classes of PKC modulators can activate the α-secretase pathway, the benzo/indolactams and bryostatin/bryologues. While both modulate PKC-dependent APP processing, no direct comparisons of their relative pharmacological potencies have been accomplished which could assist in the development of AD therapies. In this study, we measured the activation of α-secretase APP processing and PKC-α, -δ, and -ε induced by the benzolactam-APP modulator TPPB and bryostatin-1 in the neuroblastoma cell line SH-SY5Y which expresses APP and α- and β-secretase processing mechanisms. Bryostatin-1 produced a more rapid, potent, and sustained activation of α-secretase APP processing than TPPB and selectively activated PKC-δ and PKC-ε. Although TPPB also activated α-secretase, its potency was approximately 10- to 100-fold lower, possibly reflecting lower PKC-δ and -ε activation. Because bryostatin-1 is a highly potent PKC-δ and -ε activator which activates α-secretase APP processing, further characterization of bryostatin-1/bryologues may help refine their use as important tools for the clinical management of AD. Topics: Adjuvants, Immunologic; Amyloid beta-Peptides; Amyloid Precursor Protein Secretases; Benzopyrans; Bryostatins; Cell Line, Tumor; Dose-Response Relationship, Drug; Enzyme Activation; Humans; Neuroblastoma; Neurons; Protein Kinase C; Protein Kinase C-alpha; Protein Kinase C-delta; Protein Kinase C-epsilon | 2012 |
Phorbol ester-enhanced noradrenaline secretion correlates with the presence and activity of protein kinase C-alpha in human SH-SY5Y neuroblastoma cells.
The effect of inhibition and down-regulation of protein kinase C (PKC) subtypes alpha, epsilon, and zeta on noradrenaline (NA) secretion from human SH-SY5Y neuroblastoma cells was investigated. The PKC inhibitor Ro 31-7549 inhibited carbachol-evoked NA release (IC(50) 0.6 microM) but not 100 mM (K+)-evoked release. In addition, Ro 31-7549 inhibited the enhancement of carbachol- and (K+)-evoked release after pretreatment with 12-O-tetradecanoylphorbol 13-acetate (TPA; 100 nM) for 8 min, with IC50 values of 0.7 and 2.4 microM, respectively. Immunoblotting studies showed that prolonged exposure (48 h) of SH-SY5Y cells to phorbol 12,13-dibutyrate (PDBu) or bryostatin-1 caused down-regulation of PKC-alpha and PKC-epsilon but not PKC-zeta. Under these conditions, the acute TPA enhancement of NA release was inhibited. Moreover, the inhibition of TPA-enhanced secretion was also apparent after only 2-h exposure to either PDBu or bryostatin-1, conditions that caused down-regulation of PKC-alpha, but not PKC-epsilon or zeta. The PKC inhibitor Gö-6976 (2 microM), which has been shown to inhibit selectively PKC-alpha and beta in vitro, also inhibited the TPA enhancement of carbachol- and (K+)-evoked NA release by > 50%. These data suggest that in SH-SY5Y cells, the ability of TPA to enhance carbachol- and (K+)-evoked NA secretion is due to activation of PKC-alpha. Topics: Bryostatins; Carbazoles; Enzyme Activation; Enzyme Inhibitors; Humans; Indoles; Isoenzymes; Lactones; Macrolides; Maleimides; Mitogens; Neuroblastoma; Norepinephrine; Phorbol Esters; Protein Kinase C; Protein Kinase C-alpha; Time Factors; Tumor Cells, Cultured | 1996 |
Protein kinase C-alpha but not protein kinase C-epsilon is differentially down-regulated by bryostatin 1 and tetradecanoyl phorbol 13-acetate in SH-SY5Y human neuroblastoma cells.
SH-SY5Y human neuroblastoma cells can be induced to differentiate by phorbol esters but not by bryostatins although both agents increase protein kinase C (PKC) activity in these cells to a similar extent. We examined whether this difference could be explained by differences in the responses of specific PKC isoenzymes. Both TPA and bryostatin 1 at 10 nM induced a rapid increase in membrane-associated PKC-alpha immunoreactivity which was sustained for 72 hours in TPA-treated cells, but was down-regulated within 24 hours in bryostatin-treated cells. TPA likewise induced a sustained phosphorylation of an 80 kDa PKC substrate whereas in bryostatin-treated cells the 80 kDa substrate was rapidly phosphorylated reaching a maximum at 6 hours followed by a decline to basal level within 48 hours. A higher concentration of TPA (300 nM), which results in a less differentiated phenotype, induced down-regulation of PKC-alpha within 24 hours. In contrast, both TPA and bryostatin 1 stimulated translocation and a partial down-regulation of PKC-epsilon with similar kinetics. These results suggest that the divergent actions of bryostatin 1 and TPA in SH-SY5Y cells are at least partially due to differential modulation of PKC-alpha but not PKC-epsilon by these two agents. Topics: Biological Transport; Bryostatins; Cell Differentiation; Cytosol; Down-Regulation; Enzyme Activation; Humans; Isoenzymes; Lactones; Macrolides; Neuroblastoma; Phosphorylation; Protein Kinase C; Substrate Specificity; Tetradecanoylphorbol Acetate; Tumor Cells, Cultured | 1993 |
Protein kinase inhibitor, staurosporine, induces a mature neuronal phenotype in SH-SY5Y human neuroblastoma cells through an alpha-, beta-, and zeta-protein kinase C-independent pathway.
Previous studies have shown that the tumour-promoting phorbol ester 12-O-tetradecanoyl phorbol-13 acetate (TPA) induces both morphological and functional differentiation in SH-SY5Y human neuroblastoma cells (Påhlman et al., 1981). In order to investigate the role of protein kinase C (PKC) in TPA-induced maturation of SH-SY5Y cells, we have used staurosporine, which is a potent inhibitor of protein kinases including PKC. Treatment of SH-SY5Y cells with 25 nM staurosporine for 72 hours caused an appearance of long, neuritelike processes with varicosities, terminated by growth cones. The morphological differentiation was accompanied by a cessation of DNA synthesis, induction of growth associated protein 43 (GAP-43), and neuropeptide Y (NPY) mRNA. These effects of staurosporine were comparable to those elicited by TPA. Staurosporine further induced a time-dependent increase in the expression of tyrosine hydroxylase protein and a 30-fold increase in the concentration of noradrenaline. TPA only induced a marginal increase in tyrosine hydroxylase expression. Both TPA and staurosporine induced an appearance of voltage-gated Ca2+ channels in SH-SY5Y cells detected with single-cell fluorescent measurements using fura-2. The Ca2+ channels were found almost exclusively in growth cones and varicosities. Staurosporine inhibited both basal and a TPA-induced phosphorylation of an endogenous 80kDa PKC substrate (p80), and also blocked c-fos proto-oncogene mRNA expression induced by the phorbol ester. Bryostatin 1, a potent activator of PKC, has failed to induce morphological or functional differentiation in SH-SY5Y cells (Jalava et al., 1990). Incubation of SH-SY5Y cells in the presence of 100 nM bryostatin 1 for 24 hours caused a complete disappearance of all immunoreactive alpha-, beta-, and zeta-PKC. The level of epsilon-PKC decreased by 70%. Staurosporine induced a partial translocation of the epsilon-isoenzyme but it failed to cause down-regulation of epsilon-PKC. Bryostatin 1-treatment did not interfere in the ability of staurosporine to induce morphological differentiation, cessation of DNA synthesis, and GAP-43 and NPY mRNA expression. The ability of staurosporine to stimulate tyrosine hydroxylase expression and to increase cellular content of noradrenaline was also unaffected. Taken together the results of this study show that staurosporine induces a mature neuronal noradrenergic phenotype in SH-SY5Y cells through an alpha-, beta-, and zeta-PKC-independent pathwa Topics: Alkaloids; Bryostatins; Cell Differentiation; Cellular Senescence; Gene Expression; Genes, fos; Humans; Lactones; Macrolides; Neuroblastoma; Neurons; Phenotype; Phosphorylation; Protein Kinase C; Protein Kinase Inhibitors; Proto-Oncogene Mas; Staurosporine; Subcellular Fractions; Substrate Specificity; Tetradecanoylphorbol Acetate; Tumor Cells, Cultured | 1993 |
Effects of bryostatins 1 and 2 on morphological and functional differentiation of SH-SY5Y human neuroblastoma cells.
SH-SY5Y human neuroblastoma cells can be induced to differentiate to mature ganglion cells when treated with the phorbol ester tetradecanoylphorbol acetate (TPA). Bryostatins are a new class of protein kinase C activators that are structurally unrelated to phorbol esters. This paper describes the effects of bryostatins 1 and 2 on morphological and functional differentiation of SH-SY5Y cells. Both bryostatins induced a rapid translocation of protein kinase C from the cytosol to the membrane fraction. Within 24 h, the bryostatins had caused a nearly complete down-regulation of the enzyme. Bryostatin 1 competed for [3H]phorbol-12,13-dibutyrate binding in intact cells with potency equal to that of TPA, in contrast to bryostatin 2, which exhibited a Ki value 1 order of magnitude higher than those of the two other agents. Bryostatins induced morphological changes similar to those induced by TPA. These changes were, however, only transient, occurring during the first 6 h of incubation in the presence of these compounds. By 72 h, the cells had acquired a morphology typical of untreated cells and, although a wide range of bryostatin concentrations were used, morphological changes characteristic of differentiated SH-SY5Y cells were not detected at 72 h. Bryostatin 1 at 5 nM and bryostatin 2 at 100 nM inhibited DNA synthesis, as measured by incorporation of [3H]thymidine by SH-SY5Y cells, although to a significantly lesser degree than TPA. In spite of the fact that bryostatins failed to induce morphological differentiation in SH-SY5Y cells, these compounds down-regulated c-myc mRNA expression. Bryostatins were significantly weaker in stimulating noradrenaline synthesis, compared with TPA, and high concentrations of these agents blocked the effect of the phorbol ester when they were included together with TPA. When SH-SY5Y cells were incubated in the presence of high concentrations of bryostatins, a decreased sensitivity of cells to muscarinic agonist-induced increases in cytosolic free Ca2+ was observed. The results suggest that down-regulation of protein kinase C activity and c-myc mRNA expression do not necessarily correlate with the morphological differentiation of SH-SY5Y cells. Topics: Antineoplastic Agents; Bryostatins; DNA, Neoplasm; Down-Regulation; Enzyme Induction; Humans; Lactones; Macrolides; Neuroblastoma; Norepinephrine; Oncogenes; Phorbol 12,13-Dibutyrate; Protein Kinase C; Receptors, Muscarinic; RNA, Messenger; RNA, Neoplasm; Tetradecanoylphorbol Acetate; Tumor Cells, Cultured | 1990 |