• BMB Reports
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• v.42 no.8
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• pp.511-515
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• 2009

Downstream of Bid (DOBI) known as Pus10, has been identified as a modulator of TRAIL-induced cell death using RNAi library screening. The crystal structure of DOBI has revealed that it is a crescent-shaped protein containing the pseudouridine synthase catalytic domain and a THUMP-containing domain. Here, we demonstrated that DOBI is expressed in various tissues such as heart and lung, and is also expressed in various tumor cells such as HeLa and A549. Although ectopic expression of DOBI does not promote TRAIL death signaling in HeLa cells, knock-down of DOBI expression using shRNA inhibited TRAIL death signaling. DOBI is cleaved into a 54 kD cleaved DOBI during cell death, and the recombinant DOBI protein can be directly cleaved by caspases-3, or -8 in vitro. Together, these data suggest that the cleaved DOBI may acquire a new function, possibly by cooperating with tBid in the mitochondrial event of cell death caused by TRAIL.

• Animal cells and systems
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• v.16 no.4
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• pp.295-301
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• 2012

Interdigital tissue regression is one of the most well-known examples of embryonic programmed cell death, providing the mechanism behind separation of developing digits. Caspases have been shown to play a key part in this process, with activated caspase-3 localized between the developing digits. In caspase-3 knock-out adult mice, however, the digits are completely separated with no webbing. In other mutants with defects in the apoptotic machinery, such as Apaf1 deficient mice, interdigital tissue regression is initially inhibited but the webbing eventually disappears as alternative/additional cell death mechanisms step in. In order to investigate whether a similar temporal effect occurs after loss of caspase-3, we have used an in vitro approach to inhibit caspase-3 at specific times during digit separation. Previous limb explant culture approaches have encountered problems with proper limb development in culture, and thus a modified technique was used. The new approach enables detailed observation of the effects of caspase-3 inhibition on interdigital regression. Using these methods, we show that caspase-3 inhibition caused a delay in the loss of interdigital tissue compared with control explants, similar to that observed in Apaf1 mutant mice. Along with immunohistochemistry, active caspase-3 positive cells of the interdigital vs. digital regions were measured by flow cytometry. Notably, activated caspase-3 in vivo was found not only in the interdigital mesenchyme but also in the TUNEL negative digit region, supporting a role for caspase-3 in nonapoptotic events.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.9
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• pp.1363-1369
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• 2013

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) can selectively induce apoptosis by targeting cancer cells. However, some cancer cells are resistant to TRAIL-induced cytotoxicity. One method of overcoming TRAIL resistance is combination treatment with reagents to sensitize cells to TRAIL. Luteolin, a flavonoid, has been shown to have anti-cancer effects by inducing apoptosis and cell cycle arrest in various cancer cell lines in vitro. In this study, we investigated the effects of combination treatment with non-toxic concentration of TRAIL and luteolin in T24 human bladder cancer cells. Combined treatment with luteolin and TRAIL significantly inhibits cell proliferation via activation of caspases by inducing Bid truncation, up-regulation of Bax and down-regulation of X-linked inhibitor of apoptosis protein (XIAP). However, the apoptotic effects of combination treatment with luteolin and TRAIL were significantly inhibited by specific caspases inhibitors. Taken together, these results indicate that combination treatment with TRAIL and luteolin can induce apoptosis in TRAIL-resistant cancer cells through down-regulation of XIAP and modulation of tBid and Bax expression.

• BMB Reports
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• v.42 no.2
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• pp.96-100
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• 2009

Aromatic (ar)-turmerone from turmeric oil displays anti-tumorigenesis activity that includes inhibited cell proliferation. This study investigated ar-turmerone-mediated apoptotic protein activation in human lymphoma U937 cells. Ar-turmerone treatment inhibited U937 cell viability in a concentration-dependent fashion, with inhibition exceeding 84%. Moreover, the treatment produced nucleosomal DNA fragmentation and the percentage of sub-diploid cells increased in a concentration-dependent manner; both are hallmarks of apoptosis. The apoptotic effect of ar-turmerone was associated with the induction of Bax and p53 proteins, rather than Bcl-2 and p21. Activation of mitochondrial cytochrome c and caspase-3 demonstrated that the activation of caspases accompanied the apoptotic effect of ar-turmerone, which mediated cell death. These results suggest that the apoptotic effect of ar-turmerone on U937 cells may involve caspase-3 activation through the induction of Bax and p53, rather than Bcl-2 and p21.

• Journal of Pharmacopuncture
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• v.7 no.2
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• pp.19-28
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• 2004

봉독은 관절염 치료를 비롯한 여러 질환에 그 응용범위가 넓어지고 있으며 기전규명과 새로운 치료효과 개발을 위한 연구가 필요하다. 연골의 파괴는 진행된 각종 관절병증의 공통 병리기전이며 연골세포의 기능이상은 이 기전에 중요한 의미를 지닌다. 사람 연골세포의 특성을 유지하고 있는 HTB-94 연골육종세포를 배양하고 봉독을 처치했을 때의 유전자 발현양상을 microarray를 이용하여 관찰하였다. 대조군에 비해 4배 이상 발현의 차이가 있는 경우를 유의한 것으로 보았을 때 microarray의 344개 유전자중 봉독처치시 발현이 증강되는 유전자는 없었으며 발현이 억제되는 유전자는 interleukin 6 receptor, interleukin 1 alpha, tissue inhibitor of metalloproteinase 1, matrix metalloproteinase 1, tumor necrosis factor (ligand) superfamily, members 4, 8 and 12, and caspases 2, 6, and 10등 35개가 관찰되었다. Microarray를 통한 유전자발현 분석을 통해 관절염에 대한 봉독치료의 기전을 시사하는 유용한 자료를 얻을 수 있었으며 앞으로 보다 넓은 범위에 대한 연구가 필요할 것이다.

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2003.05a
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• pp.68-69
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• 2003

• Journal of Microbiology and Biotechnology
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• v.19 no.8
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• pp.787-791
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• 2009

In the course of screening for substances that inhibit etoposide (10 ${\mu}g$/ml)-induced apoptosis in human leukemia U937 cells, fungal strain F000120, which exhibits potent inhibitory activity, was selected. The active compound was purified from an ethyl acetate extract of the microorganism by Sep-pak $C_{18}$ column chromatography and HPLC, and was identified as heptelidic acid (koningic acid) by spectroscopic methods. This compound inhibited caspase-3 induction in U937 cells with an $IC_{50}$ value of 40 ${\mu}M$ after 8 h of etoposide treatment. Fluorescent dye staining with acridine orange and ethidium bromide showed that heptelidic acid inhibited apoptosis. Furthermore, it was found that DNA fragmentation and caspase-3 activation, the biological hallmarks of apoptosis, were inhibited by the compound in a dose-dependent manner, suggesting that heptelidic acid inhibits etoposide-induced apoptosis via downregulation of caspases.

• Journal of Microbiology and Biotechnology
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• v.19 no.3
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• pp.286-290
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• 2009

In the course of screening for substances inhibiting apoptosis of U937 human leukemia cells induced by etoposide ($10\;{\mu}g/ml$), Forsythiae fructus, which showed a high level of inhibition, was selected. The regulating compounds were purified from the ethyl acetate extract by silica gel column chromatography and HPLC. The active substance was purified and identified as rengyolone by spectroscopic methods. This compound showed inhibitory activity on caspase-3 induction, a major protease of the apoptosis cascade, with an $IC_{50}$ value of $38.96\;{\mu}M$ after 8 h of etoposide treatment in U937 cells. The expression level of caspase-3 and poly(ADP-ribose) polymerase (PARP) were dose-dependently inhibited by the compound, suggesting that rengyolone inhibits etoposide-induced apoptosis via downregulation of caspases.

• Journal of Microbiology and Biotechnology
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• v.19 no.9
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• pp.946-950
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• 2009

In the course of screening for apoptotic substances that induce apoptosis in human leukemia U937 cells, a fungal strain, F000487, which exhibits potent inducible activity, was selected. The active compound was purified from an ethyl acetate extract of the microorganism by Sep-pak $C_{18}$ column chromatography and HPLC, and was identified as atromentin by spectroscopic methods. This compound induced caspase-3 processing in human leukemia U937 cells. The caspase-3 and poly (ADP-ribose) polymerase (PARP) were induced by atromentin in a dose-dependent manner. Furthermore, DNA fragmentation was also induced by this compound in a dose-dependent manner. These results show that atromentin potently induces apoptosis in U937 cells and that atromentin-induced apoptosis is related to the selective activation of caspases.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.2
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• pp.761-767
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• 2015

Background: In this study, we used Daucus carota oil extract (DCOE) to target acute myeloid leukemia (AML) cells. All the AML cell lines tested were sensitive to the extract while peripheral mononuclear cells were not. Analysis of mechanism of cell death showed an increase in cells positive for annexinV and for active caspases, indicating that DCOE induces apoptotic cell death in AML. Inhibition of the MAPK pathway decreased sensitivity of AML cells to DCOE, indicating that cytotoxicity may be dependent on its activity. In conclusion, DCOE induces selective apoptosis in AML cells, possibly through a MAPK-dependent mechanism.