Paclitaxel Induces Apoptosis in Saos-2 Cells with CD95L Upregulation and Bcl-2 Phosphorylation

We examined the effect of paclitaxel on human osteoblastic cells Saos-2 to determine if paclitaxel can affect proliferation and apoptosis. We used a p53-negative cell line in order to mimic the loss of function frequently observed at the clinical level. Paclitaxel induced cell death in a dose- and t...

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Bibliographic Details
Published in:Experimental cell research 1999-10, Vol.252 (1), p.134-143
Main Authors: Pucci, Bruna, Bellincampi, Lorenza, Tafani, Marco, Masciullo, Valeria, Melino, Gerry, Giordano, Antonio
Format: Article
Language:English
Subjects:
Antineoplastic Agents, Phytogenic - pharmacology
apoptosis
Apoptosis - drug effects
Apoptosis - immunology
Apoptosis - physiology
Bcl-2
Caspases - physiology
CD95
Cell Cycle - drug effects
Cell Division - drug effects
Fas Ligand Protein
fas Receptor - metabolism
Humans
Membrane Glycoproteins - biosynthesis
Microscopy, Electron
Osteoblasts - cytology
Osteoblasts - drug effects
Osteoblasts - physiology
osteosarcoma
Osteosarcoma - drug therapy
Osteosarcoma - pathology
Osteosarcoma - physiopathology
paclitaxel
Paclitaxel - pharmacology
Phosphorylation
Proto-Oncogene Proteins c-bcl-2 - metabolism
Tumor Cells, Cultured
Up-Regulation - drug effects
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Summary:We examined the effect of paclitaxel on human osteoblastic cells Saos-2 to determine if paclitaxel can affect proliferation and apoptosis. We used a p53-negative cell line in order to mimic the loss of function frequently observed at the clinical level. Paclitaxel induced cell death in a dose- and time-dependent manner. Marked nuclear condensation and fragmentation of chromatin were observed by Hoechst 33258 stain, DNA ladder formation, electron microscopy, and flow cytometry at concentrations as low as 100 nM, a concentration which can be achieved by infusion in human plasma. At 100 nM, paclitaxel induced a G2 arrest at 8 h of treatment. The cells then continued to accumulate in G2 until 72 h when the percentage of apoptotic events reached 54%. At the molecular level, Bcl-2 protein was phosphorylated at 16 h and PARP protein was cleaved, indicating the activation of caspase-3-like proteases. Caspase inhibitors Z-VAD-FMK and Z-DEVD-FMK rescued Saos-2 cells from paclitaxel-induced apoptosis. CD95 expression was constantly high, while CD95L showed a threefold increase in expression. This suggests that, following the G2 arrest, apoptosis is induced through the CD95/CD95L system.
ISSN:0014-4827
1090-2422
DOI:10.1006/excr.1999.4591