• Journal of Microbiology and Biotechnology
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• v.24 no.12
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• pp.1654-1663
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• 2014

To examine the effect of tumor suppressor protein p53 on the antitumor activity of 2-methoxyestradiol (2-MeO-$E_2$), 2-MeO-$E_2$-induced cell cycle changes and apoptotic events were compared between the human colon carcinoma cell lines HCT116 ($p53^{+/+}$) and HCT116 ($p53^{-/-}$). When both cell types were exposed to 2-MeO-$E_2$, a reduction in the cell viability and an enhancement in the proportions of $G_2/M$ cells and apoptotic sub-$G_1$ cells commonly occurred dose-dependently. These 2-MeO-$E_2$-induced cellular changes, except for $G_2/M$ arrest, appeared to be more apparent in the presence of p53. Immunofluorescence microscopic analysis using anti-${\alpha}$-tubulin and anti-lamin B2 antibodies revealed that after 2-MeO-$E_2$ treatment, impaired mitotic spindle network and prometaphase arrest occurred similarly in both cell types. Following 2-MeO-$E_2$ treatment, only HCT116 ($p53^{+/+}$) cells exhibited an enhancement in the levels of p53, p-p53 (Ser-15), $p21^{WAF1/CIP1}$, and Bax; however, the Bak level remained relatively constant in both cell types, and the Bcl-2 level decreased only in HCT116 ($p53^{+/+}$) cells. Additionally, mitochondrial apoptotic events, including the activation of Bak and Bax, loss of ${\Delta}{\psi}m$, activation of caspase-9 and -3, and cleavage of lamin A/C, were more dominantly induced in the presence of p53. The Bak-specific and Bax-specific siRNA approaches confirmed the necessity of both Bak and Bax activations for the 2-MeO-$E_2$-induced apoptosis in HCT116 cells. These results show that among 2-MeO-$E_2$-induced apoptotic events, including prometaphase arrest, up-regulation of Bax level, down-regulation of Bcl-2 level, activation of both Bak and Bax, and mitochondria-dependent caspase activation, the modulation of Bax and Bcl-2 levels is the target of the pro-apoptotic action of p53.

• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.419-424
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• 2014

The pro-apoptotic BCL-2 family protein BID activates BAK and/or BAX, which form oligomeric pores in the mitochondrial outer membrane. This results in the release of cytochrome c into the cytoplasm, initiating the apoptotic cascade. Here, we utilized liposomes encapsulating sulfo-rhodamine at a controlled temperature to improve upon a previously reported assay system with enhanced sensitivity and specificity for measuring membrane permeabilization by BID-dependent BAK activation. BAK activation was inhibited by BCL-$X_L$ protein but not by a mutant protein with impaired anti-apoptotic activity. With the assay system, we screened a chemical library and identified several compounds including trifluoperazine, a mitochondrial apoptosis-induced channel blocker. It inhibited BAK activation by direct binding to BAK and blocking the oligomerization of BAK.

• Journal of Life Science
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• v.23 no.10
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• pp.1230-1238
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• 2013

The regulatory effect of the tumor-suppressor protein p53 on the apoptogenic activity of $17{\alpha}$-estradiol ($17{\alpha}-E_2$) was compared between HCT116 ($p53^{+/+}$) and HCT116 ($p53^{-/-}$) cells. When the HCT116 ($p53^{+/+}$) and HCT116 ($p53^{-/-}$) cells were treated with $2.5{\sim}10{\mu}M$ $17{\alpha}-E_2$ for 48 h or with $10{\mu}M$for various time periods, cytotoxicity and an apoptotic sub-$G_1$ peak were induced in the HCT116 ($p53^{+/+}$) cells in a dose- and time-dependent manner. However, the HCT116 ($p53^{-/-}$) cells were much less sensitive to the apoptotic effect of $17{\alpha}-E_2$. Although $17{\alpha}-E_2$ induced aberrant mitotic spindle organization and incomplete chromosome congregation at the equatorial plate, $G_2/M$ arrest was induced to a similar extent in both cell types. In addition, $17{\alpha}-E_2$-induced activation of Bak and Bax, ${\Delta}{\Psi}m$ loss, and PARP degradation were more dominant in the HCT116 ($p53^{+/+}$) than in the HCT116 ($p53^{-/-}$) cells. In accordance with enhancement of p53 phosphorylation (Ser-15) and p53 levels, p21 and Bax levels were elevated in the HCT116 ($p53^{+/+}$) cells treated with $17{\alpha}-E_2$. The HCT116 ($p53^{-/-}$) cells exhibited barely or undetectable levels of p21 and Bax, regardless of $17{\alpha}-E_2$ treatment. On the other hand, although the level of Bcl-2 was slightly lower in the HCT116 ($p53^{+/+}$) than in the HCT116 ($p53^{-/-}$) cells, it remained relatively constant after the $17{\alpha}-E_2$ treatment. Together, these results show that among the components of the $17{\alpha}-E_2$-induced apoptotic-signaling pathway, which proceeds through mitotic spindle defects causing mitotic arrest, subsequent activation of Bak and Bax and the mitochondria-dependent caspase cascade, leading to PARP degradation, $17{\alpha}-E_2$-induced activation of Bak and Bax is the upstream target of proapoptotic action of p53.

• Journal of Life Science
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• v.33 no.1
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• pp.15-24
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• 2023

To examine the antitumor effect of proso millet grains, whether proso millet grains exert apoptotic activity against human cancer cells was investigated. When the cytotoxicity of 80% ethanol (EtOH) extract of proso millet grains was tested against various cancer cells using MTT assay, more potent cytotoxicity was observed against human breast cancer MDA-MB-231 cells than against other cancer cells. When the EtOH extract was evaporated to dryness, dissolved in water, and then further fractionated by sequential extraction using four organic solvents (n-hexane, methylene chloride, ethyl acetate, and n-butanol), the BuOH fraction exhibited the highest cytotoxicity against MDA-MB-231 cells. Along with the cytotoxicity, TUNEL-positive apoptotic nucleosomal DNA fragmentation and several apoptotic responses including BAK/BAX activation, mitochondria membrane potential (Δψm) loss, mitochondrial cytochrome c release into the cytosol, activation of caspase-8/-9/-3, and degradation of poly (ADP-ribose) polymerase (PARP) were detected. However, human normal mammary epithelial MCF-10A cells exhibited a significantly lesser extent of sensitivity compared to malignant MDA-MB-231 cells. Irrespective of Fas-associated death domain (FADD)-deficiency or caspase-8-deficiency, human T acute lymphoblastic leukemia Jurkat cells displayed similar sensitivities to the cytotoxicity of BuOH fraction, excluding an involvement of extrinsic apoptotic mechanism in the apoptosis induction. These results demonstrate that the cytotoxicity of BuOH fraction from proso millet grains against human breast cancer MDA-MB-231 cells is attributable to intrinsic apoptotic cell death resulting from BAK/BAX activation, and subsequent mediation of mitochondrial damage-dependent activation of caspase cascade.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.9
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• pp.1257-1264
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• 2016

Extracts from Artemisia annua $Linn\acute{e}$ (AAE) have various functions (anti-malaria, anti-virus, and anti-oxidant). However, the mechanism of the effects of AAE is not well known. Thus, we determined the apoptotic effects of AAE in AGS human gastric carcinoma cells. In this study, we suggested that AAE may exert cancer cell apoptosis through the Akt/mammalian target of rapamycin (mTOR)/glycogen synthase kinase (GSK)-$3{\beta}$ signal pathway and mitochondria-mediated apoptotic proteins. Activation by Akt phosphorylation resulted in cell proliferation through phosphorylation of tuberous sclerosis complex 2 (TSC2), mTOR, and GSK-$3{\beta}$. Thus, de-phosphorylation of Akt inhibited cell proliferation and induced apoptosis through inhibition of Akt, mTOR, phosphorylation of GSK-$3{\beta}$ at serine9, and control of Bcl-2 family members. Inhibition of GSK-$3{\beta}$ attenuated loss of mitochondrial membrane potential and release of cytochrome C. Bax and pro-apoptotic proteins were activated by their translocation into mitochondria from the cytosol. Translocation of Bax induced outer membrane transmission and generated apoptosis through cytochrome C release and caspase activity. We also measured 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, lactate dehydrogenase assay, Hoechst 33342 staining, Annexin V-PI staining, 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethyl-imidacarbocyanine iodide staining, and Western blotting. Accordingly, our study showed that AAE treatment to AGS cells resulted in inhibition of Akt, TSC2, GSK-$3{\beta}$-phosphorylated, Bim, Bcl-2, and pro-caspase 3 as well as activation of Bax and Bak expression. These results indicate that AAE induced apoptosis via a mitochondrial event through regulation of the Akt/mTOR/GSK-$3{\beta}$ signaling pathways.

• Journal of Ginseng Research
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• v.39 no.1
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• pp.22-28
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• 2015

Background: Sun ginseng (SG), a specific formulation of quality-controlled red ginseng, contains approximately equal amounts of three major ginsenosides (RK1, Rg3, and Rg5), which reportedly has antitumor-promoting activities in animal models. Methods: MTT assay was used to assess whether SG can potentiate the anticancer activity of epirubicin or paclitaxel in human cervical adenocarcinoma HeLa cells, human colon cancer SW111C cells, and SW480 cells; apoptosis status was analyzed by annexin V-FITC and PI and analyzed by flow cytometry; and apoptosis pathway was studied by analysis of caspase-3, -8, and -9 activation, mitochondrial accumulation of Bax and Bak, and cytochrome c release. Results: SG remarkably enhances cancer cell death induced by epirubicin or paclitaxel in human cervical adenocarcinoma HeLa cells, human colon cancer SW111C cells, and SW480 cells. Results of the mechanism study highlighted the cooperation between SG and epirubicin or paclitaxel in activating caspase-3 and -9 but not caspase-8. Moreover, SG significantly increased the mitochondrial accumulation of both Bax and Bak triggered by epirubicin or paclitaxel as well as the subsequent release of cytochrome c in the targeted cells. Conclusion: SG significantly potentiated the anticancer activities of epirubicin and paclitaxel in a synergistic manner. These effects were associated with the increased mitochondrial accumulation of both Bax and Bak that led to an enhanced cytochrome c release, caspase-9/-3 activation, and apoptosis. Treating cancer cells by combining epirubicin and paclitaxel with SG may prove to be a novel strategy for enhancing the efficacy of the two drug types.

• Journal of Physiology & Pathology in Korean Medicine
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• v.30 no.3
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• pp.150-156
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• 2016

Extract of Broussometia kazinoki Rhizodermatis has been traditionally used for geopoong, diuresis, hwalhyeol. In the present study, the apoptotic effect of methanol extract of Broussometia kazinoki (MBK) were investigated. Cell viability of A549 cells was measured by MTT assay. Apoptosis-related protein and MAPK protein levels were measured by Western blot. Chromatin condensation of A549 cells was stained with DAPI. MBK inhibited cell proliferation of A549 cell. Based on DAPI staining, MBK-treated cells manifested nuclear shrinkage, condensation and fragmentation. Treatment of A549 cells with MBK resulted in activation of the caspase-3, -8, -9 and cleavage of poly ADP-ribose polymerase (PARP). In the upstream, MBK increased the expressions Bax and Bak, decreased the expression of Bcl-2, and augmented the Bax/Bcl-2 ratio. MBK-induced apoptosis was accompanied by sustained phosphorylation of JNK, p38 MAPK and apoptosis signal-regulating kinase (ASK)-1. These results suggest that MBK induced apoptosis in A549 cells through Bcl-2 family protein-mediated mitochondria/caspase-3 dependent pathway. In addition, MBK increased the activation of ASK-1, which are critical upsteam signals for JNK/p38 MAPK activation in A549 cancer cells.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.1
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• pp.75-82
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• 1999

It has been reported that activation of sphingomyelin pathway and nonsteroidal anti-inflammatory drugs (NSAIDS) inhibit the promotion of colon carcinoma. Ceramide, a metabolite of sphingomyelin, and indomethacin were shown to induce apoptosis in colon carcinoma cells. However, the mechanisms of ceramide- and indomethacin-induced apoptosis in the colon carcinoma cells are not clearly elucidated. Recent studys showed that indomethacin-induced apoptosis in colon cancer cells through the cyclooxygenase-independent pathways, and that may be mediated by generation of ceramide. In this study, we compared effects of ceramide and indomethacin on important modulators of apoptotic processes in HT29 cells, a human colon cancer cell line. Ceramide and indomethacin induced apoptosis dose- and time- dependently. Ceramide and indomethacin increased stress-activated protein kinase (SAPK) activity, and decreased mitogen-activated protein kinase (MAPK) activity. The expression of Bak was increased by the treatment of ceramide and indomethacin. The expression of other Bcl-2 related proteins (Mcl-1, $Bcl-X_L,$ Bax) which were known to be expressed in colon epithelial cells was not changed during the ceramide- and indomethacin-induced apoptosis. Our results suggest that ceramide and indomethacin share common mechanisms for induction of apoptosis in HT29 cells.

• Journal of Life Science
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• v.26 no.8
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• pp.887-894
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• 2016

The extract from Artemisia annuain L.(AAE) is known as a medicinal herb that is effective against cancer. Apoptosis is the process of programmed cell death, and mitochondria are known to play a central role in cell death control. In this study, we evaluated the p53-independent apoptosis of extract of AAE through downregulation of Bcl-2 and the mitochondrial pathway in A549 (lung cancer cells). AAE may exert cancer cell apoptosis through regulating p-Akt, Cox-2, p53 and mitochondria-mediated apoptotic proteins. p-Akt/cox-2 is known to play an important role in cell proliferation and cell survival. The Bcl-2 pro-apoptotic proteins (such as Bax, Bak and Bim) mediate the permeabilization of the mitochondrial outer membrane. Treatment of AAE reduces p-Akt, p-Mdm2, cox-2 and anti-apoptotic proteins (such as Bcl-2), while tumor suppressor p53 and pro-apoptotic proteins. Activation of Bax/Bak releases cytochrome c from mitochondria to the cytosol to activate a caspase. Caspase-3 is the major effector caspase associated with apoptotic pathways. Caspase-3 generally exists in cytoplasm in the form of a pro-enzyme. In the initiation stage of apoptosis, caspase-3 is activated by proteolytic cleavage and activated caspase-3 cleaves poly (ADP-ribose) polymerase (PARP). We treated Pifithrin-α (p53 inhibitor) and Celecoxib (Cox-2 inhibitor) to learn the relationship between the signal transduction of proteins associated with apoptosis. These results suggest that AAE induces apoptosis through a p53-independent pathway in A549.

• Journal of Life Science
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• v.26 no.7
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• pp.764-771
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• 2016

Extracts from Artemisia annua Linné (AAE) have been known to possess various functions, including anti-bacterial, anti-virus, and anti-oxidant effects. However, the mechanism of those effects of AAE is not well-known. The aim of this study was to analyze the inhibitory effects of AAE on cell proliferation of the human hepatoma cell line (Hep3B) and to examine its effects on apoptosis. Activation by phosphorylation of Akt is cell proliferation through the phosphorylation of TSC2, mTOR, and GSK-3β. We suggested that AAE may exert cancer cell apoptosis through Akt/mTOR/GSK-3β signal pathways and mitochondria-mediated apoptotic proteins. For this, we examined the effects of extracts of AAE on cell proliferation according to treatment concentration. Treatment with AAE not only reduced cell viability, but also resulted in the induced release of lactate dehydrogenase (LDH). These results were determined with a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and a lactate dehydrogenase (LDH) assay. Furthermore, we determined the effects of apoptosis through Hoechst 33342 staining, annexinⅤ-propidium iodide (PI) staining, 5,5′, 6,6′-tetrachloro-1,1′,3,3′-tetraethyl-imidacarbocyanine iodide (JC-1) staining, and Western blotting. Our study showed that the treatment of liver cancer cells with AAE resulted in the inhibition of Akt, TSC2, GSK-3β-phosphorylated, Bcl-2, and pro-caspase 3 and the activation of Bim, Bax, Bak, and cleaved PARP expressions. These results indicate that AAE induced apoptosis by means of a mitochondrial event through the regulate of Akt/mTOR/GSK-3β signaling pathways.