Differential IGF-independent effects of insulin-like growth factor binding proteins (1-6) on apoptosis of breast epithelial cells

Autor: C M, Perks, S, Bowen, Z P, Gill, P V, Newcomb, J M, Holly
Rok vydání: 1999
Předmět:
Zdroj: Journal of cellular biochemistry. 75(4)
ISSN: 0730-2312
Popis: We have demonstrated previously that insulin-like growth factor binding protein (IGFBP)-3 alone has little growth inhibitory effect on Hs578T human breast cancer cells, but that it can dramatically accentuate the apoptotic response to the physiological trigger, ceramide, in an IGF-independent manner. We have now studied the potential of other IGFBPs (1-6) to interact with apoptotic signalling pathways. Hs578T cells were preincubated with a binding protein (100 ng/ml) for 24 h, followed by co-incubation of the binding protein with an apoptotic dose of ceramide or RGD-containing peptide for a further 24 h. Apoptosis was assessed using flow cytometry, MTT (3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide; thiazolyl blue) assay and morphological assessment. Binding protein profiles were determined using ligand and immunoblotting techniques. Each of the IGFBPs (1-6) alone had no significant (P0. 05) growth inhibitory effects relative to control cells. In contrast to IGFBP-3, which significantly (P0.05) accentuated C2-induced apoptosis, IGFBP-1, -2, and -6 had no effect, whereas IGFBP-4 and -5 each caused marked (P0.01) inhibition of ceramide-induced programmed cell death. Apoptosis induced by RGD was also significantly (P0.05) reduced by IGFBP-5, whereas IGFBP-3 had no effect. These data provide evidence to suggest that individual IGFBPs have specific IGF-independent effects and act differentially on apoptotic signalling pathways.
Databáze: OpenAIRE
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