• Archives of Pharmacal Research
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• v.24 no.2
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• pp.126-135
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• 2001

Quinacrine (QU), a phospholipase-A2 (PLA-2) inhibitor has been used clinically as a chemotherapeutic adjuvant. To understand the mechanisms leading to its chemotherapeutic effect, we have investigated QU-induced apoptotic signaling pathways in human cervical squamous carcinoma HeLa cells. In this study, we found that QU induced cytochrome c-dependent apoptotic signaling. The release of pro-apoptotic cytochrome c was QU concentration- and time-dependent, and preceded activation of caspase-9 and -3. Flow cytometric FACScan analysis using fluorescence intensities of $DiOC_6$/ demonstrated that QU-induced cytochrome c release was independent of mitochondrial permeability transition (MPT), since the concentrations of QU that induced cytochrome c release did not alter mitochondrial membrane potential (${\blacktriangle}{\Psi}_m$). Moreover, kinetic analysis of caspase activities showed that cytochrome c release led to the activation of caspase-9 and downstream death effector caspase-3, Caspase-3 inhibitor (Ac-DEVD-CHO) partially blocked QU-induced apoptosis, suggesting the importance of caspase-3 in this apoptotic signaling mechanism. Supplementation with arachidonic acid (AA) sustained caspase-3 activation induced by QU. Using inhibitors against cellular arachidonate metabolism of lipooxygenase (Nordihydroxyguaiaretic Acid, NDGA) and cyclooxygenase (5,8,11,14-Eicosatetraynoic Acid, ETYA) demonstrated that QU-induced apoptotic signaling may be dependent on its role as a PLA-2 inhibitor. Interestingly, NDCA attenuated QU-induced cytochrome c release, caspase activity as well as apoptotic cell death. The blockade of cytochrome c release by NDCA was much more effective than that attained with cyclosporin A (CsA), a MPT inhibitor. ETYA was not effective in blocking cytochrome c release, except under very high concentrations. Caspase inhibitor z-VAD blocked the release of cytochrome c suggesting that this signaling event is caspase dependent, and caspase-8 activation may be upstream of the mitochondrial events. In summary, we report that QU induced cytochrome c-dependent apoptotic signaling cascade, which may be dependent on its role as a PLA-2 inhibitor. This apoptotic mechanism induced by QU may contribute to its known chemotherapeutic effects.

• Archives of Pharmacal Research
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• v.26 no.11
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• pp.937-942
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• 2003

Nitric oxide(NO) induces apoptosis in human osteoblasts. Treatment with exogenous NO donors, SNAP (S-Nitroso-N-acelylpenicillamine) and SNP (sodium nitroprusside), to MG-63 osteoblasts resulted in apoptotic morphological changes, as shown by a bright blue-fluorescent condensed nuclei and chromatin fragmentation by fluorescence microscope of Hoechst 33258-staining. The activities of caspase-9 and the subsequent caspase-3-like cysteine proteases were increased during NO-induced cell death. Pretreatment with Z-VAD-FMK (a pancaspase inhibitor) or Ac-DEVD-CHO (a specific caspase-3 inhibitor) abrogated the NO-induced cell death. The NO donor markedly activated JNK, a stress-activated protein kinase in the human osteoblasts. This study showed that the inhibition of the JNK pathway markedly reduced NO-induced cell death. But neither PD98059 (MEK inhibitor) nor SB203580 (p38 MAPK inhibitor) had any effect on NO-induced death. Taken together, these results suggest that JNK/SAPK may be related to NO-induced apoptosis in MG-63 human osteoblasts.

• Journal of the Korean Chemical Society
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• v.52 no.6
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• pp.717-723
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• 2008

• Journal of Photoscience
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• v.9 no.2
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• pp.509-511
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• 2002

In this study, we investigated apoptotic cell death induced by photodynamic therapy using 5-aminolaevulinic acid (ALA-PDT) in human promyelocytic leukemia cells (HL-60). ALA-PDT induced apoptosis in HL-60 cells as confirmed by DNA agarose gel electrophoresis and nuclear staining with Hoechst 33342. The apoptotic cell death was inhibited by addition of broad-spectrum caspase inhibitor Z-Asp-CH$_2$-DCB, indicating that the apoptotic cell death was induced in a caspase-dependent manner. Actually, western blotting analysis revealed that caspase-3 was processed as early as 1.5 h after ALA-PDT. Cytoplasmic cytochrome c released from mitochondria was detected by western blotting. However, inhibitor of caspase-9, a cysteine protease located in the downstream of cytochrome c release, was not able to reduce the apoptotic cell death. Therefore, the mitochondrial apoptotic pathway was not involved in the ALA-PDT-induced apoptosis. On the other hand, it was found that ALA-PDT-induced apoptosis was clearly inhibited by pretreatment of caspase-8 inhibitor. These data suggest that caspase-8-mediated apoptotic pathway is important in ALA-PDT-induced cell death.

• Korean Journal of Food Science and Technology
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• v.35 no.4
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• pp.680-683
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• 2003

Through the screening of caspase-3 inducing inhibitors in U937 human monocytic leukemia cell from natural sources, Caesalpiniae sappan, which showed a high level of inhibition, was selected. The inhibition compound was purified from methanol extract by silica gel column chromatography and HPLC. The inhibitor was identified as brazilin by spectroscopic methods of ESI-MS, $^1H-NMR$, and $^{13}C-NMR$. Brazilin showed inhibitory activity of caspase-3 induction, a major protease of apoptosis cascade, with $IC_{50}$ value of $4.5\;{\mu}g/mL$ after 7 hr of treatment in U937 cells.

• Journal of Life Science
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• v.19 no.11
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• pp.1529-1537
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• 2009

To elucidate further the antitumor effects of a natural L-arginine analogue, L-canavanine, the mechanism underlying apoptogenic activity of L-canavanine and its modulation by protein tyrosine kinase $p56^{lck}$ was investigated in human Jurkat T cells. When the cells were treated with 1.25 to 2.5 mM L-canavanine for 36 h, several apoptotic events including mitochondrial membrane potential (${\Delta\Psi}m$) loss, activation of caspase-9, -3, -8, and -7, poly (ADP-ribose) polymerase (PARP) degradation, and DNA fragmentation were induced without alteration in the levels of Fas or FasL. These apoptotic changes were more significant in $p56^{lck}$-deficient Jurkat clone JCaM1.6 than in $p56^{lck}$-positive Jurkat clone E6.1. The L-canavanine-induced apoptosis observed in $p56^{lck}$-deficient JCaM1.6 cells was significantly reduced by introducing $p56^{lck}$ gene into JCaM1.6 cells by stable transfection. Treatment of JCaM1.6/lck cells with L-canavanine caused a transient 1.6-fold increase in the kinase activity of $p56^{lck}$. Both FADD-positive wild-type Jurkat T cell clone A3 and FADD-deficient Jurkat T cell clone I2.1 exhibited a similar susceptibility to the cytotoxicity of L-canavanine, excluding involvement of Fas/FasL system in triggering L-canavanine-induced apoptosis. The L-canavanine-induced apoptotic sub-$G_1$ peak and activation of caspase-3, -8, and -7 were abrogated by pan-caspase inhibitor (z-VAD-fmk), whereas L-canavanine-induced activation of caspase-9 was not affected. These results demonstrated that L-canavanine caused apoptosis of Jurkat T cells via the loss of ${\Delta\Psi}m$, and the activation of caspase-9, -3, -8, and -7, leading to PARP degradation, and that the $p56^{lck}$ kinase attenuated the ${\Delta\Psi}m$ loss and activation of caspases, and thus contributed as a negative regulator to L-canavanine-induced apoptosis.

• Journal of Korean Medicine Rehabilitation
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• v.19 no.2
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• pp.103-112
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• 2009

Objectives : This study was to evaluate the pharmacological effect of Korea Red Ginseng aqueous extract (KRGE) on serum-deprived apoptosis of neuronal-like pheochromocytoma PC12 cells and to investigate its underlying action mechanism. Methods : KRGE was prepared by extracting Korea Red Ginseng with hot water and concentrating using a vacuum evaporator. Cell viability was determined after incubation of cells with KRGE or chemical inhibitor in serum-deprived medium for 60 h by counting intact nuclei following lysing of the cell membrane. Caspase activities were measured using chromogenic substrates and signal-associated protein phosphorylation and cytochrome c release were determined by Western blot analyses using their specific antibodies. Results : Serum deprivation induced PC12 cell death, which was accompanied by typical morphological features of apoptotic cell, such as nuclear fragmentation, caspase-3 activation, and cytochrome c release. This apoptotic cell death was significantly inhibited by KRGE and caspase-3 inhibitor, but not by the addition of NMA, ODQ, and PD98059. KRGE promoted phosphorylation of Akt and Bad, and this phosphorylation was inhibited by the PI3K inhibitor LY92004. In addition, this inhibitor also reversed KRGE-mediated protection of PC 12 cells from serum deprivation. These results suggested that KRGE protects PC12 cells from serum deprivation-induced apoptosis through the activation of PI3K/Akt-dependent Bad phosphorylation and cytochrome c release, resulting in caspase-3 activation. Conclusions : KRGE should be considered as a potential therapeutic drug for brain diseases including stroke induced by apoptosis of neuronal cells.

• Journal of Life Science
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• v.9 no.1
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• pp.9-13
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• 1999

Reduced thiols were important compounds for the maintenance of leukemia and lymphoma cell survival (and growth). In the course of examining the microenvirn-mental effects on lymphoma and leukemia cell growth, we found that cysteine suppressed apoptosis in these cells. In a present study, in order to investigate the role of cystein on the suppression of apoptotic cell death, we used CS21, P388, and L1210 cell lines. The addition of BSO, an inhibitor of glutathione synthase, induced apoptosis of these cells by blocking the cellular uptake of cysteine in CS21 cells. Although L1210 cells underwent apoptosis without thiol compounds, the addition of these compounds suppressed the apoptosis and promoted the growth or L1210 cells. When specific inhibitors of caspase3-like proteases, but not caspase1-like proteases, were activated during the L1210 cell apoptosis but the addition of thiol compounds suppressed the activation of caspase3-like proteases. These results suggest that reduced thiols including cysteine play an important role in the suppression of cell apoptosis by inhibiting the activation of caspase3-like proteases.

• Toxicological Research
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• v.19 no.3
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• pp.197-203
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• 2003

Apicidin, a histone-deacetylase inhibitor, has been successfully used to inhibit the growth of cancer cells. In this study, the apoptotic potential and mechanistic insights of apicidin were investigated in human myeloid leukemia U937 cells. Treatment of U937 cells with apicidin resulted in a decrease of cell viability with apoptotic characteristics, including chromatin condensation and ladder-pattern fragmentation of genomic DNA. Apicidin converted the procaspase-3 protease to catalytically active effector protease, resulting in subsequent cleavage of poly (ADP-ribose) polymerase (PARP) and inhibitor of caspase-activated deoxyribonuclease (ICAD). In addition, apicidin induced the activation of caspase-9 protease and the cytosolic release of mitochondrial cytochrome c with mitochon-drial membrane potential transition. Moreover, apicidin transiently increased the expression of Fas and Fas ligand proteins. Taken together, the results suggest that apicidin induces apoptosis of U937 cells through activation of intrinsic caspase cascades and Fas/FasL system with mitochondrial dysfunction.

• Proceedings of the Korean Biophysical Society Conference
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• 2001.06a
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• pp.34-34
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• 2001

Survivin, an apoptosis inhibitor/cell-cycle regulator, is critically required for suppression of apoptosis and ensuring normal cell division in the G2/M phase of the cell cycle. It is highly expressed in a cell cycle-regulated manner and localizes together with caspase-3 on microtubules within centrosomes. Whether survivin is a physiologically relevant caspase inhibitor has been unclear due to the difficulties with obtaining correctly folded survivin and finding right conditions for inhibition assay.(omitted)