• Natural Product Sciences
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• v.21 no.4
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• pp.282-288
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• 2015

Viriditoxin is a fungal metabolite isolated from Paecilomyces variotii, which was derived from the giant jellyfish Nemopilema nomurai. Viriditoxin was reported to inhibit polymerization of FtsZ, which is a key protein for bacterial cell division and a structural homologue of eukaryotic tubulin. Both tubulin and FtsZ contain a GTP-binding domain, have GTPase activity, assemble into protofilaments, two-dimensional sheets, and protofilament rings, and share substantial structural identities. Accordingly, we hypothesized that viriditoxin may inhibit eukaryotic cell division by inhibiting tubulin polymerization as in the case of bacterial FtsZ inhibition. Docking simulation of viriditoxin to ${\beta}-tubulin$ indicated that it binds to the paclitaxel-binding domain and makes hydrogen bonds with Thr276 and Gly370 in the same manner as paclitaxel. Viriditoxin suppressed growth of A549 human lung cancer cells, and inhibited cell division with G2/M cell cycle arrest, leading to apoptotic cell death.

• The Journal of Internal Korean Medicine
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• v.28 no.4
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• pp.694-708
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• 2007

Objectives : Jageum-Jung is used as an anti-cancer agent in oriental medicine, but the mechanism by which it induces cell death in cancer cells is still unclear. The purpose of this study was to investigate the effects of Jageum-Jung on apoptosis and cell cycle arrest in HepG2 hepatoma cells. Methods : Various cancer cell lines including HepG2, C6 glioma, SH-SY5Y, PANC-1, and MCF-7 cells, were used. Apoptosis was determined by DAPI nuclei staining and flow cytometry in HepG2 cells treated with various concentrations (from 25 to 200 ${\mu}g/ml$) of $H_2O$ extract of Jageum-Jung (JGJ) for 48 hrs. Expression of cell cycle arrest mediators including Rb, p53, p21, cyclin B1, cdk4, and cyclin E proteins were measured by Western blot analysis. To estimate intracellular hydrogen peroxide levels and intracellular nitric oxide levels, HepG2 cells were stained with DCFH-DA dye and DAF dye, subjected on flow cytometric analysis. Results : 1. Jageum-Jung decreased the viability of HepG2 cells in a dose-dependent manner. 2. Jageum-Jung induced the catalytic activation of caspase-3 in HepG2 cells. 3. Jageum-Jung increased the intracellular hydrogen peroxide and NO in HepG2 cells. 4. Jageum-Jung increased the expression of Rb, p53 and p21 in HepG2 cells. 5. Jageum-Jung induced the expression of cyclin B1, cdk4, and cyclin E in HepG2 cells. Conclusions : Taken together, we suggest that Jageum-Jung exhibits cytotoxic effects on HepG2 cells, causing apoptosis and cell cycle arrest. The results showed that Jageum-Jung may do so by regulating the expression of specific target molecules that promote efficient apoptotic cell death following $G_2$/M phase arrest in a dose-dependent manner.

• Biomolecules & Therapeutics
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• v.17 no.3
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• pp.282-287
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• 2009

Ochnaflavone is a natural biflavonoid and mainly found in the caulis of Lonicera japonica (Caprifoliaceae). Biological activities such as anti-inflammatory and anti-atherogenic effects have been previously reported. The anticancer activity of ochnaflavone, however, has been poorly elucidated yet. In the present study, we investigated the effect of ochnaflavone on the growth inhibitory activity in cultured human colon cancer cell line HCT-15. Ochnaflavone inhibited the proliferation of the cancer cells with an $IC_{50}$ value of $4.1{\mu}M$. Flow cytometric analysis showed that ochnaflavone arrested cell cycle progression in the G2/M phase, and induced the increase of sub-G1 peak in a concentration-dependent manner. Induction of cell cycle arrest was correlated with the modulation of the expression of cell cycle regulating proteins including cdc2 (Tyr15), cyclin A, cyclin B1 and cyclin E. The increase of sub-G1 peak by the higher concentrations of ochnaflavone (over $20{\mu}M$) was closely related to the induction of apoptosis, which was evidenced by the induction of DNA fragmentation, activation of caspase-3, -8 and -9, and cleavage of poly-(ADP-ribose) polymerase. These findings suggest that the cell cycle arrest and induction of apoptosis might be one possible mechanism of actions for the anti-proliferative activity of ochnaflavone in human colon cancer cells.

• Natural Product Sciences
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• v.18 no.1
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• pp.16-21
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• 2012

Honokiol, a naturally occurring neolignan mainly found in Magnolia species, has been shown to have the anti-angiogenic, anti-invasive and cancer chemopreventive activities, but the molecular mechanism of actions has not been fully elucidated yet. In the present study, we investigated the effect of honokiol on the growth inhibitory activity in cultured SNU-638 human gastric cancer cells. We found that honokiol exerted potent antiproliferative activity against SNU-638 cells. Honokiol also arrested the cell cycle progression at the G0/G1 phase and induced the apoptotic cell death in a concentration-dependent manner. The cell cycle arrest was well correlated with the downregulation of Rb, cyclin D1, cyclin A, cyclin E, and CDK4 expression, and the induction of cyclin-dependent kinase inhibitor p27. The increase of sub-G1 peak by honokiol was closely related to the induction of apoptosis, which was evidenced by the induction of DNA fragmentation, the cleavage of poly(ADPribose) polymerase, and the sequential activation of caspase cascade. These findings suggest the cell cycle arrest and induction of apoptosis might be one possible mechanism of actions for the anti-proliferative activity of honokiol in human gastric cancer cell.

• Journal of Microbiology and Biotechnology
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• v.31 no.12
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• pp.1615-1623
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• 2021

Picropodophyllotoxin (PPT), an epimer of podophyllotoxin, is derived from the roots of Podophyllum hexandrum and exerts various biological effects, including anti-proliferation activity. However, the effect of PPT on colorectal cancer cells and the associated cellular mechanisms have not been studied. In the present study, we explored the anticancer activity of PPT and its underlying mechanisms in HCT116 cells. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to monitor cell viability. Flow cytometry was used to evaluate cell cycle distribution, the induction of apoptosis, the level of reactive oxygen species (ROS), assess the mitochondrial membrane potential (Δψm), and multi-caspase activity. Western blot assays were performed to detect the expression of cell cycle regulatory proteins, apoptosis-related proteins, and p38 MAPK (mitogen-activated protein kinase). We found that PPT induced apoptosis, cell cycle arrest at the G1 phase, and ROS in the HCT116 cell line. In addition, PPT enhanced the phosphorylation of p38 MAPK, which regulates apoptosis and PPT-induced apoptosis. The phosphorylation of p38 MAPK was inhibited by an antioxidant agent (N-acetyl-L-cysteine, NAC) and a p38 inhibitor (SB203580). PPT induced depolarization of the mitochondrial inner membrane and caspase-dependent apoptosis, which was attenuated by exposure to Z-VAD-FMK. Overall, these data indicate that PPT induced G1 arrest and apoptosis via ROS generation and activation of the p38 MAPK signaling pathway.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2003.11a
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• pp.86-86
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• 2003

In a continuous effort to develop novel anticancer agents we newly synthesized and evaluated the antitumor activity of nucleoside analogues. One analogue, 4 - ［2-Chlor-6- (3-iodo- benzy lamino) -purin -9-yl］- 2,3-dihydroxy-cyclopentanecarbo xylic acid methylamide (LJ-331), has been shown to exert a potent inhibition of human cancer cell growth in vitro including human lung (A549), stomach (SNU-638) and leukemia (HL-60) cancer cells. Following mechanism of action study revealed that LJ - 331induces cell cycle arrest at the G1 phase in HL-60 cells and evokes apoptotic phenomena such as an increase in DNA ladder intensity and chromatin condensation by a dose- and time-dependent manner. LJ-331 also activated the caspase-3 activity in HL-60. This result suggests that the growth inhibition of human cancer cells by LJ-331 might be related to the cell cycle arrest and induction of apoptosis.

• Proceedings of the Korean Society of Toxicology Conference
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• 2002.11b
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• pp.138-138
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• 2002

8-hydroxydeoxyguanosine (oh8dG) potently inhibits proliferation of KG-1, a human leukemia cell line in vitro, but little is known regarding to molecular mechanisms mediating this effect. Here we demonstrate that treatment of KG-1, deficient in 8-oxoguanine glycosylase (OGG1) activity, with oh8dG lead to G1 arrest associated with a dramatic decrease in the levels of cyclin D3 and cyclin-dependent kinase 4 (cdk4) and accompanied by an increase in the expression of p21.(omitted)

• Environmental Mutagens and Carcinogens
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• v.24 no.3
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• pp.113-120
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• 2004

Chromium compounds are known human and animal carcinogens. In this study, the effects of sodium chromate on apoptosis and cell cycle were investigated in order to unveil the elements of early cellular responses to the metal. Using Chinese hamster ovary cells(CHO-K1-BH4), we found taht chromium (VI) treatment induced apoptosis in these cells, as signified by nuclear fragmentation, DNA laddering on agarose gel electrophoresis, and an increased proportionof cells with hypodiploid DNA. Preceding these changes, chromium (VI) treatment increased caspase 3 pritease activity and also increased expression of p53 protein, while the level of bcl2 protein was not changed. Coincubation with caspase inhibitor, Z-DEVD-FMK, inhibited chromium-induced apoptosis. In the flow cytometric analysis using propidium iodide fluorescence, an increase of cell population in G2/M phase was shown in cells exposed to at least 160 $\mu\textrm{m}$ of sodium chromate for 72h, form 9.8% for 0$\mu\textrm{m}$ chromium (VI) to 26.4% for 320$\mu\textrm{m}$ chromium(VI). Taken together, these findings suggest that chromium(VI)-induced apoptosis is accompanied by G2/M cell cycle arrest, and that p53-mediated pathway may be involved in positive regulation of G2/M arrest and a concurred apoptosis in CHO cells.

• Archives of Pharmacal Research
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• v.28 no.11
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• pp.1263-1269
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• 2005

Recently, it was reported that reduction in serum adiponectin levels is correlated with the incidence of breast cancer. As an effort to explain this, we screened various human breast cancer cell lines to identify those in which proliferation is directly controlled by adiponectin. Among the five tested cell lines, proliferation of MDA-MB-231 cancer cell was significantly suppressed by adiponectin within the range of physiological concentration. Furthermore, prolonged adiponectin treatment caused cell growth arrest and even apoptosis of MDA-MB-231. This result is the first to show that adiponectin can directly control cancer cell growth and provides a rationale for the theory that reduction in plasma adiponectin levels could be a risk factor for breast cancer.

• Archives of Pharmacal Research
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• v.27 no.6
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• pp.640-645
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• 2004

Histone deacetylase inhibitors are new class of chemotherapeutic drugs able to induce tumor cell apoptosis and／or cell cycle arrest. Trichostatin A, an antifungal antibiotic, and HC-toxin are potent and specific inhibitors of histone deacetylase activity. In this study, we have examined the antiproliferative activities of trichostatin A and HC-toxin in estrogen receptor positive human breast cancer, T47D cells. Both trichostatin A and HC-toxin showed potent antiprolifer-ative efficacy and cell cycle arrest at $G_2/M$ in T47D human breast cancer cells in a dose-dependent manner. Trichostatin A caused potent apoptosis of T47D human breast cancer cells and trichostatin A-induced apoptosis might be involved in an increase of caspase-3／7 activity. HC-toxin evoked apoptosis of T47D cells and HC-toxin induced apoptosis might not be medi-ated through direct increase in caspase-3/7 activity. We have identified potent activities of anti-proliferation, apoptosis, and cell cycle arrest of trichostatin A and HC-toxin in estrogen receptor positive human breast cancer cell line T47D.