cytochrome-c-t and Neurilemmoma

Malignant peripheral nerve sheath tumours (MPNSTs) are invasive, hard-to-treat, soft tissue sarcomas. In this study, in vitro and in vivo effects of triptolide were investigated using human MPNST cell lines.. Cultured STS-26T and ST88-14 cells were treated with 0-100 ng/ml triptolide (for determination of cell proliferation by sulphorhodamine B assay), with 12.5 ng/ml or 25 ng/ml triptolide (for analysis of caspase activity, effects on apoptotic pathway intermediates [by Western blots and flow cytometry], and for measurement of vascular endothelial growth factor [VEGF] and epidermal growth factor receptor [EGFR] levels by enzyme-linked immunosorbent assay). A xenograft model was established by injection of STS-26T cells into nude mice, and the effects of 250 μg/kg triptolide on tumour growth and apoptosis were compared with controls.. Triptolide significantly inhibited cell proliferation and induced apoptosis in vitro, through activation of caspases, in a dose- and time-dependent manner; VEGF and EGFR levels were suppressed. In vivo, triptolide inhibited the growth of STS-26T xenografts and reduced apoptosis.. Triptolide may have a therapeutic benefit in MPNST treatment.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Apoptosis; Caspase 3; Caspase 8; Caspase 9; Cell Line, Tumor; Cell Proliferation; Cytochromes c; Diterpenes; Enzyme Activation; Epoxy Compounds; ErbB Receptors; Female; Humans; Mice; Mice, Nude; Neoplasm Transplantation; Neurilemmoma; Phenanthrenes; Proto-Oncogene Proteins c-bcl-2; Vascular Endothelial Growth Factor A; Xenograft Model Antitumor Assays

In response to different stress signals, the c-Jun NH(2)-terminal kinase (JNK) can trigger cell death. However, JNK also facilitates the survival and cell cycle progression of tumor cells by mechanisms that are poorly defined. Here, we show that schwannoma RN22 cells can survive and proliferate under serum-free conditions although serum withdrawal rapidly induces mitochondrial fission and swelling. Although the morphologic changes observed in the mitochondria did not trigger cytochrome c release, they were accompanied by an increase in the mitochondrial membrane potential (DeltaPsi(M)) and of immunoreactivity for active JNK in these organelles. Pharmacologic inhibition of JNK provoked a further increase of the DeltaPsi(M), an increase in reactive oxygen species (ROS) production, and a sustained decrease in cell viability due to necrosis. This increase in necrosis was prevented by the presence of ROS scavengers. Immunoreactivity for active JNK was also observed in the mitochondria of neuroblastoma 1E-115 and neuroblastoma 2a neuroblastoma cell lines on serum withdrawal, whereas active JNK was barely detected in serum-deprived fibroblasts. Accordingly, the reduction in neural tumor cell viability induced by JNK inhibition was largely attenuated in serum-deprived fibroblasts. These data indicate that local activation of JNK in the mitochondria can protect against necrotic cell death associated with ROS production, facilitating the growth of neural tumor cells subjected to serum deprivation.

Topics: Animals; Cell Death; Culture Media, Serum-Free; Cytochromes c; Enzyme Inhibitors; JNK Mitogen-Activated Protein Kinases; Membrane Potential, Mitochondrial; Mice; Mitochondria; Mitogen-Activated Protein Kinases; Necrosis; Neurilemmoma; Neuroblastoma; Oxidative Stress; Rats; Reactive Oxygen Species; Tumor Cells, Cultured