Simvastatin induces proliferation inhibition and apoptosis in C6 glioma cells via c-jun N-terminal kinase.
The lipid-lowering drugs, statins, induce apoptosis in a variety of tumor cells. Here we investigated the apoptotic effect of the lipophilic statin, simvastatin, in C6 glioma cells and the underlying effects on intracellular signal transduction. Simvastatin inhibited cell proliferation totally after 20h of treatment as shown by the decrease in proliferating cell nuclear antigen expression in the nucleus. Subsequently, simvastatin caused apoptotic cell death by shrinkage of cytoplasm and condensation of chromatin, and DNA fragmentation. The features of apoptosis were visible only after 48 h of treatment, possibly reflecting a requirement for cell commitment to growth arrest. In immunocytochemical and immunoblotting experiments we have shown that simvastatin markedly increased the phosphorylation of ATF-2 and c-jun in the nucleus of the C6 glioma cells at early time points which was preserved even 24 h after treatment. In contrast, activities of protein kinases Erk1/2 and AKT in the cell survival pathway remained unchanged throughout the treatment. Selective inhibitor of JNK, but not p38 kinase, reduced simvastatin-induced cell death and ATF-2 and c-jun phosphorylation suggesting that JNK-dependent activation of ATF-2 and c-jun may play an important role in simvastatin-induced proliferation inhibition and apoptosis in C6 glioma cells. These observations suggest that statins may have clinical significance in the prevention of glial tumors beyond their cholesterol-lowering effect and JNK may be a rational target for sensitizing glioma cells to chemotherapeutic agents.
Koyuturk
Meral
M
Department of Histology and Embryology, Kadir Has University Faculty of Medicine, Istanbul, Turkey.
Ersoz
Melike
M
Altiok
Nedret
N
D051698:Activating Transcription Factor 2; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor / Q000166:cytology / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D005910:Glioma; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology*; D007150:Immunohistochemistry / Q000379:methods; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D051379:Mice; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D019821:Simvastatin / Q000494:pharmacology*; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism
D051698:Activating Transcription Factor 2; C497106:Atf2 protein, mouse; D017362:Cyclic AMP Response Element-Binding Protein; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D018809:Proliferating Cell Nuclear Antigen; D011518:Proto-Oncogene Proteins; D016755:Proto-Oncogene Proteins c-jun; D014157:Transcription Factors; D019821:Simvastatin; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D048031:JNK Mitogen-Activated Protein Kinases; D048052:Mitogen-Activated Protein Kinase 3