• Biomedical Science Letters
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• v.17 no.4
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• pp.291-295
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• 2011

PD98059 is the specific inhibitor of extracellular signaling-regulated kinase (ERK) kinase (MEK). ERK is involved in a mitogen-activated protein kinase (MAPK) cascade controlling cell growth and differentiation. Although the inhibition of ERK is known to induce cell death in various cell lines, this effect is still controversial and the role of PD98059 on the death of HeLa $S_3$ cells, a subclone of the cervical cancer cell line, is not well understood. The apoptosis of HeLa $S_3$ cells increased after the treatment of 50 ${\mu}M$ PD98059. The induction of apoptosis by PD98059 was occurred in a time- and a dose-dependent manners. The expression of Bcl-2 was reduced in accordance with decrease of ERK2 expression. Taken together, these results indicate that PD98059 has a cytotoxicity in HeLa $S_3$ cells and it may be used as a potential target for the treatment of cervical cancer.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2021.04a
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• pp.56-56
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• 2021

Nypa fruticans Wurmb is a mangrove plant belonging to Araceae family. N. fruticans is typically found in Southeast Asia, and in some parts of Queensland, Australia. N. fruticans has phytochemicals, phenolics, and flavonoids. In this study, we investigated the anti-inflammatory effects of the ethyl acetate fraction of N. fruticans (ENF) on the production and expression of cytokines and inflammatory mediators through the major signal transduction pathways. ENF attenuated the level of cytokines in a dose-dependent manner and decreased the production of nitric oxide (NO). ENF decreased the expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) via alleviating transcription of nuclear factor-kappa B (NF-κB) by an inhibitor of nuclear factor-kappa B (IκB) degradation. Furthermore, mitogen-activated protein kinase (MAPK) signaling pathways (ERK1/2, JNK1/2, and p38) are known to be involved in the inflammatory response. Phosphorylations of ERK1/2, JNK1/2, and p38 were significantly decreased compared with the ENF-untreated control. Conclusively, ENF was related to alleviating various pro-inflammatory mediators through IκB/NF-κB and MAPK signaling pathways, including p65 translocation to the nucleus.

• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.5
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• pp.1297-1302
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• 2007

Uncaria sinensis(OIi.) Havil (USH) is used in traditional Korean medicine to treat inflammation such as amebic dysentery. In this study, we investigated the anti-inflammatory effect of USH. The water extract of USH significantly inhibits lipopolysaccharide (LPS)-induced nitrite oxide (NO), tumor necrosis factor $(TNF)-{\alpha}$, interleukin (IL)-6and IL-12 productions in murine peritoneal macrophages. Furthermore, USH selectively inhibited activation of the extracellular signal-regulated kinase (ERK) but not of p38 MAPK, c-Jun N-terminal kinase (JNK) and nuclear $factor-{\kappa}B$ $(NF-{\kappa}B)$. In murine model, we found that administration of USH reduced serum levels of $TNF-{\alpha}$, IL-6 and IL-12 productions in LPS-treated mice. Our results suggest that USH exerts ant-inflammatory effects in macrophages via inhibition of ERK activation and may be a useful therapeutic approach to inflammatory diseases.

• The Korean Journal of Physiology and Pharmacology
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• v.8 no.4
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• pp.187-194
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• 2004

Middle cerebral artery occlusion (MCAO) results in cell death by activation of complex signal pathways for cell death and survival. Hypothermia is a robust neuroprotectant, and its effect has often been attributed to various mechanisms, but it is not yet clear. Upstream from the cell death promoters and executioners are several enzymes that may activate several transcription factors involved in cell death and survival. In this study, we immunohistochemically examined the phosphorylation of mitogen-activated protein kinase, extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 kinase during early period of the ischemic injury, following 2 hours (h) of transient MCAO. Increased phosphorylation of ERK and p38 was observed in the vessels at 3 h, neuron-like cells at 6 and 12 h and glia-like cells at 12 h. Activation of JNK was not remarkable, and a few cells showed active JNK following ischemia. Phosphorylation of Elk-1, a transcription factor, was reduced by ischemic insult. Hypothermia attenuated the activation of ERK, p38 and JNK, and inhibited reduction of Elk-1. These data suggest that signals via different MAPK family members converge on the cell damage process and hypothermia protects the brain by interfering with these pathways.

• The Journal of Korean Medicine
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• v.29 no.4
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• pp.171-179
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• 2008

Objective: Bufonis Venenum is the traditional Korean medicine Chan Su, which is obtained from the skin and parotid venom gland of the toads. It has been used for myocardial diseases, inflammation diseases, pain relief, cancer and others. The main components of BV are cinobufotoxin, cinobufalin, bufalin and others. Of these, bufalin, the major active ingredient of BV, has been reported to induce apoptosis and to possess anti-tumor effects. There was no report of anti-tumor screening of BV on hepatic cancer and which signaling pathway can be involved. In order to examine the effect of BV on hepatic cancer and the related signaling pathway with BV-induced apoptosis, human Hep G2 cells were used. Methods: Analysis of apoptosis was confirmed by MTT assay. BV decreased cell viability in a dose and duration dependent manner. To observe which signaling molecules will be activated by BV, phosphorylation of MAPK (p38, ERK, JNK), caspase 8 and caspase 9 were examined by Western blot analysis. Results: The phosphorylation levels of p38 started to increase at 5 min after addition of 5 ${\mu}g$/ml of BV and sustained to increase until 48 hours. The phosphorylation levels of other MAPK (ERK and JNK), caspase 8 and caspase 9 increased in a time-dependent manner. These imply that BV may activate different signaling pathways, MAPK, caspase 8 and caspase 9. These results propose that BV may induce apoptosis on Hep G2 cells through the activation of MAPK, caspase 8 and caspase 9.

• Archives of Pharmacal Research
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• v.29 no.11
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• pp.1024-1031
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• 2006

The role of mitogen-activated protein kinase (MAPK) in the decreased contractile response to phorbol ester in aortic smooth muscle strips from deoxycorticosterone acetate (DOCA)-salt hypertensive rats was examined. Norepinephrine (NE) evoked greater contractility in aortic strips from DOCA rats than in those of sham-operated rats. 12-Deoxyphorbol 13-isobutyrate (DPB) induced contraction in $Ca^{2+}-free$ medium, which was diminished in strips from DOCA rats compared to sham-operated rats. Vasoconstrictions induced by these stimulants were inhibited by SB203580 and PD098059, inhibitors of p38 MAPK and extracellular signal-regulated kinase (ERK) 1/2, respectively, in both strips. The phosphorylation of p38 MAPK and ERK1/2 induced by NE was greater in strips from DOCA rats compared to those from sham-operated rats, and this phosphorylation was inhibited by the kinase inhibitors. DPB increased the phosphorylation of p38 MAPK and ERK1/2 in strips from both animals, and the increment of p38 MAPK phosphorylation by the stimulant was diminished in strips from DOCA rats compared to sham-operated rats. These findings suggest that the $Ca^{2+}-independent$ contraction evoked by DPB results from the activation of MAPKs in rat aortic smooth muscle and that the attenuated contractility by DPB in DOCA rat appears to be associated with diminished p38 MAPK activity.

• Proceedings of the Microbiological Society of Korea Conference
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• 2005.05a
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• pp.45-48
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• 2005

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.11
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• pp.5709-5714
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• 2012

Objective: To evaluate the effects of curcumin on matrixmetalloproteinase-9 (MMP-9) and invasion ability induced by transforming growth factor-${\beta}1$ (TGF-${\beta}1$) in MDA-MB-231 cells and potential mechanisms. Methods: Human breast cancer MDA-MB-231 cells were used with the CCK-8 assay to measure the cytotoxicity of curcumin. After treatment with 10 ng/ml TGF-${\beta}1$, with or without curcumin (${\leq}10{\mu}M$), cell invasion was checked by transwell chamber. The effects of curcumin on TGF-${\beta}1$-stimulated MMP-9 and phosphorylation of Smad2, extracellular-regulated kinase (ERK), and p38 mitogen activated protein kinases (p38MAPK) were examined by Western blotting. Supernatant liquid were collected to analyze the activity of MMP-9 via zymography. Following treatment with PD98059, a specific inhibitor of ERK, and SB203580, a specific inhibitor of p38MAPK, Western blotting and zymography were employed to examine MMP-9 expression and activity, respectively. Results: Low dose curcumin (${\leq}10{\mu}M$) did not show any obvious toxicity to the cells, while $0{\sim}10{\mu}mol/L$ caused a concentration-dependent reduction in cell invasion provoked by TGF-${\beta}1$. Curcumin also markedly inhibited TGF-${\beta}1$-regulated MMP-9 and activation of Smad2, ERK1/2 and p38 in a dose- and time-dependent manner. Additionally, PD98059, but not SB203580, showed a similar pattern of inhibition of MMP-9 expression. Conclusion: Curcumin inhibited TGF-${\beta}1$-stimulated MMP-9 and the invasive phenotype in MDA-MB-231 cells, possibly associated with TGF-${\beta}$/Smad and TGF-${\beta}$/ERK signaling.

• The Korean Journal of Physiology and Pharmacology
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• v.17 no.2
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• pp.157-162
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• 2013

Insulin-like growth factor binding proteins (IGFBPs) are important components of insulin growth factor (IGF) signaling pathways. One of the binding proteins, IGFBP-5, enhances the actions of IGF-1, which include the enhanced proliferation of smooth muscle cells. In the present study, we examined the expression and the biological effects of IGFBP-5 in vascular smooth muscle cells (VSMCs) from spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). The levels of IGFBP-5 mRNA and protein were found to be higher in the VSMC from SHR than in those from WKY. Treatment with recombinant IGFBP-5-stimulated VSMC proliferation in WKY to the levels observed in SHR. In the VSMCs of WKY, incubation with angiotensin (Ang) II or IGF-1 dose dependently increased IGFBP-5 protein levels. Transfection with IGFBP-5 siRNA reduced VSMC proliferation in SHR to the levels exhibited in WKY. In addition, recombinant IGFBP-5 significantly up-regulated ERK1/2 phosphorylation in the VSMCs of WKY as much as those of SHR. Concurrent treatment with the MEK1/2 inhibitors, PD98059 or U0126 completely inhibited recombinant IGFBP-5-induced VSMC proliferation in WKY, while concurrent treatment with the phosphatidylinositol-3 kinase inhibitor, LY294002, had no effect. Furthermore, knockdown with IGFBP-5 siRNA inhibited ERK1/2 phosphorylation in VSMC of SHR. These results suggest that IGFBP-5 plays a role in the regulation of VSMC proliferation via ERK1/2 MAPK signaling in hypertensive rats.

• Journal of Microbiology and Biotechnology
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• v.21 no.9
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• pp.903-913
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• 2011

Vibrio parahaemolyticus, which causes gastroenteritis, wound infection, and septicemia, has two sets of type III secretion systems (TTSS), TTSS1 and TTSS2. A TTSS1-deficient vcrD1 mutant of V. parahaemolyticus showed an attenuated cytotoxicity against HEp-2 cells, and a significant reduction in mouse lethality, which were both restored by complementation with the intact vcrD1 gene. V. parahaemolyticus also triggered phosphorylation of mitogen-activated protein kinases (MAPKs) including p38 and ERK1/2 in HEp-2 cells. The ability to activate p38 and ERK1/2 was significantly affected in a TTSS1-deficient vcrD1 mutant. Experiments using MAPK inhibitors showed that p38 and ERK1/2 MAPKs are involved in V. parahaemolyticus-induced death of HEp-2 cells. In addition, caspase-3 and caspase-9 were processed into active forms in V. parahaemolyticus-exposed HEp-2 cells, but activation of caspases was not essential for V. parahaemolyticus-induced death of HEp-2 cells, as shown by both annexin V staining and lactate dehydrogenase release assays. We conclude that secreted protein(s) of TTSS1 play an important role in activation of p38 and ERK1/2 in HEp-2 cells that eventually leads to cell death via a caspase-independent mechanism.