• Journal of Life Science
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• v.13 no.6
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• pp.849-855
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• 2003

Nitric oxide (NO) plays an important role as a signaling molecule in the proliferation of placenta trophoblasts. In this study, we investigated the effect of NO on the activation of phospholipase C (PLC) in BeWo cells, choriocar-cinoma cell line. Sodium nitroprusside (SNP), an agent to produce NO spontaneously in cells, alone increased $［^3H］$ thymidine incorporation of BeWo cells, indicating NO stimulates proliferation of the cells. NO-induced proliferation of BeWo cells was blocked by U73122, an inhibitor of PLC, suggesting that NO-induced PLC activation is involved in the cell proliferation. NO also stimulated extracellular signal-regulated kinase (ERK) in BeWo cells, indicated by increased phosphorylation of ERK1/2 in Western blotting using anti-phospho-ERK1/2 antibody. NO-induced phos-phorylation of ERK1/2 was not abrogated by U73122. $PLC\gamma_1$l but not$PLC\gamma_2$ was tyrosine phosphorylated by SNP in immunoprecipitation assay using anti-$PLC\gamma_1$/$PLC\gamma_2$ antibodies, and SNP-induced phosphorylation of $PLC\gamma_1$ was abrogated by pre-treatment of cells with genistein and PD98059, indicating that NO induced-phosphorylation of $PLC\gamma_1$ is mediated by ERK. These results suggest that NO stimulates the proliferation of BeWo cells through ERK and $PLC\gamma_1$.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.242.1-242.1
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• 2002

H$_2$O$_2$ has been shown to act as a signaling molecule involved in many cellular functions such as oxidant-induced stress, apoptosis, proliferation. In this study, we investigated the action mechanisms of H$_2$O$_2$ on activation of Extracellular Signal-Regulated Protein Kinase(ERK) in cultured feline ileal smooth muscle cells(ISMC). Western blot analysis done with phospho-specific MAP kinases antibodies demonstrated that potent activation of ERK and moderate activation of SAPK/JNK occurred within 30 min of H$_2$O$_2$ treatment. (omitted)

• Korean Journal of Biological Psychiatry
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• v.20 no.4
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• pp.159-165
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• 2013

Objectives Mechanisms of clinical synergistic effects, induced by co-treatments of lithium and valproate, are unclear. Extracellular signal-regulated kinase (ERK) has been suggested to play important roles in mechanisms of the action of mood stabilizers. In this study, effects of co-treatments of lithium and valproate on the ERK1/2 signal pathway and its down-stream transcription factors, ELK1 and C-FOS, were investigated in vitro. Methods PC12 cells, human pheochromocytoma cells, were treated with lithium chloride (30 mM), valproate (1 mM) or lithium chloride + valproate. The phosphorylation of ERK1/2 was analyzed with immunoblot analysis. Transcriptional activities of ELK1 and C-FOS were analyzed with reporter gene assay. Results Single treatment of lithium and valproate increased the phosphorylation of ERK and transcriptional activities of ELK1 and C-FOS, respectively. Combined treatments of lithium and valproate induced more robust increase in the phosphorylation of ERK1/2 and transcriptional activities of ELK1 and C-FOS, compared to those in response to single treatment of lithium or valproate. Conclusions Co-treatments of lithium and valproate induced synergistic increase in the phosphorylation of ERK1/2 and transcriptional activities of its down-stream transcription factors, ELK1 and C-FOS, compared to effects of single treatment. The findings might suggest potentiating effects of lithium and valproate augmentation treatment strategy.

• YAKHAK HOEJI
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• v.52 no.2
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• pp.111-116
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• 2008

Diethylstilbestrol (DESB) is a synthetic estrogen not only that routinely prescribed, but also that known to be a teratogen. In this study, we found a novel pharmacological feature that DESB is able to positively modulate CD29 $({\beta}1-integrin)$ function. Thus, DESB up-regulated homotypic cell-cell adhesion of monocytic U937 cells mediated by CD29. However, DESB did not increase the surface level of CD29 and its binding activity to ligand (fibronectin), according to flow cytometric analysis and cell-fibronectin adhesion assay. Instead, the DESB-mediated up-regulation of cell-cell adhesion was blocked by several signaling enzyme inhibitors. Treatment of U0126 [an extracellular signal-regulated kinase (ERK) inhibitor], SB20358 (a p38 inhibitor) or Rp-8-pCPT-cGMP (a protein kinase G inhibitor) clearly inhibited DESB-mediated up-regulation of cell-cell adhesion induced by CD29. However, estrogen receptor antagonist ICI 182,780 failed to abrogate DESB effect. Therefore, our data suggest that DESB may up-regulate CD29-mediated cell-cell adhesion via modulating intracellular signaling enzymes such as ERK, PKG, and p38, independent of estrogen receptor function.

• Journal of Applied Biological Chemistry
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• v.63 no.4
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• pp.457-462
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• 2020

Pancreatic cancer is among the most difficult-to-treat tumors. More than half of patients with this cancer have very few symptoms at the early stages, allowing the development of distant metastases and resistance to cancer treatment. In this study, we found that Juniperus chinensis extract (JCX) decreased the cell viability and migration activity of PANC-1 and SNU-213 pancreatic cancer cells in a dose-dependent manner. JCX increased caspase-3 activation and generation of reactive oxygen species (ROS). N-acetylcysteine treatment blocked JCX-induced ROS generation and the negative effects on pancreatic cancer cell viability. In addition, JCX down-regulated the levels of phospho-focal adhesion kinase (p-FAK) and phospho-extracellular signal-regulated kinase (p-ERK). Together, these results indicate that JCX induces apoptosis in human pancreatic cancer cell lines through ROS production, downregulating FAK/ERK signaling and activating caspase-3. We propose that JCX-derived compounds represent candidates for the development of alternative medicines for the treatment of pancreatic cancer.

• Journal of Oriental Neuropsychiatry
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• v.21 no.1
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• pp.125-144
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• 2010

Objectives: The purpose of this study was to characterize the effect of the fraction of Korean mountain ginseng folium (FKG) on the learning and memory impairments induced by scopolamine. Methods: The memory ameliorating effect of FKG was investigated using a passive avoidance test, the Y-maze test, and the Morris water maze test in mice. Drug-induced amnesia was induced by treating animals with scopolamine(1mg/kg, i.p.). Results: FKG (2 or 4mg/kg, p.o.) administration significantly reversed scopolamine-induced cognitive impairments in mice by the passive avoidance test and the Y-maze test(P<0.05), and also improved escape latency in the Morris water maze test at 2 or 4mg/kg(P<0.05). Although FKG has little inhibitory activity for AChE (IC50 value; 1847 ${\mu}g/ml$) in an invitro study, phosphorylated extracellular signal-regulated kinase(pERK) was increased by the administration of FKG inhippocampus on immunohistochemistry. Conclusions: These results suggest that FKG may be a useful cognitive impairment treatment, and its beneficial effects are mediated, in part, via activation of ERK pathway.

• Journal of Physiology & Pathology in Korean Medicine
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• v.19 no.2
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• pp.501-507
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• 2005

Shikonin is a chemically characterized component of traditional herbal medicine, the root of Lithospermum erythrorhizon and has been shown to possess antitumor activities. Here we investigated anticancer potential of shikonin and its possible mechanism of action in LLC cells. Shikonin inhibited the proliferation of LLC cells in a concentration-dependent manner. It was also demonstrated that shikonin induced apoptosis in LLC cells by Annexin V staining and TUNEL staining analysis. Shikonin treatment was caused that decrease of Bcl-2, activation of caspases and cleavage of PARP. And shikonin also induced that the activation of mitogen-activated protein kinases (MAPKs), such as extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38. Interestingly, the cell proliferation inhibition induced by shikonin was recovered by specific inhibitors of JNK and p38 but the inhibitor of MEK, the upstream kinase of ERK, did not recover. Additionally, shikonin administration at doses of 5 mg/kg in C57BL/6 mice strongly inhibited the primary tumor growth of LLC. Taken together, these results suggest that shikonin may suppress LLC cell proliferation by inducing an apoptotic process via activation of caspases and MAPKs

• The Korean Journal of Physiology and Pharmacology
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• v.15 no.4
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• pp.245-249
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• 2011

Amphetamine, a synthetic psychostimulant, is transported by the dopamine transporter (DAT) to the cytosol and increases the exchange of extracellular amphetamine by intracellular dopamine. Recently, we reported that the phosphorylation levels of ezrin-radixin-moesin (ERM) proteins are regulated by psychostimulant drugs in the nucleus accumbens, a brain area important for drug addiction. However, the significance of ERM proteins phosphorylation in response to drugs of abuse has not been fully investigated. In this study, using PC12 cells as an in vitro cell model, we showed that amphetamine increases ERM proteins phosphorylation and protein kinase C (PKC) ${\beta}$ inhibitor, but not extracellular signal-regulated kinase (ERK) or phosphatidylinositol 3-kinases (PI3K) inhibitors, abolished this effect. Further, we observed that DAT inhibitor suppressed amphetamine-induced ERM proteins phosphorylation in PC12 cells. These results suggest that $PKC{\beta}$-induced DAT regulation may be involved in amphetmaine-induced ERM proteins phosphorylation.

• Journal of Microbiology and Biotechnology
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• v.25 no.5
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• pp.589-597
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• 2015

It has been reported that overexpression of MUC5AC induced by excessive inflammation leads to airway obstruction in respiratory diseases such as chronic obstructive pulmonary disease and asthma. 15-Hydroxyeicosatetraenoic acid (15-HETE) has been reported to have anti-inflammatory effects, but the role of 15-HETE in respiratory inflammation has not been determined. Therefore, the aim of this study was to investigate the effects of 15-HETE on MUC5AC expression and related pathways. In this study, phorbol-12-myristate-13-acetate (PMA) was used to stimulate NCI-H292 bronchial epithelial cells in order to examine the effects of 15-HETE. 15-HETE inhibited PMA-induced expression of MUC5AC mRNA and secretion of MUC5AC protein. Moreover, 15-HETE regulated matrix metallopeptidase 9 (MMP-9), mitogen-activated protein kinase kinase (MEK), and extracellular signal-regulated kinase (ERK). In addition, 15-HETE decreased the nuclear translocation of specificity protein-1 (Sp-1) transcription factor and nuclear factor κB (NF-κB). Furthermore, 15-HETE enhanced the transcriptional activity of peroxisome proliferator-activated receptor gamma (PPARγ) as a PPARγ agonist. This activity reduced the phosphorylation of protein kinase B (PΚB/Akt) by increasing the expression of phosphatase and tensin homolog (PTEN). In conclusion, 15-HETE regulated MUC5AC expression via modulating MMP-9, MEK/ERK/Sp-1, and PPARγ/PTEN/Akt signaling pathways in PMA-treated respiratory epithelial cells.

• BMB Reports
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• v.44 no.3
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• pp.182-186
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• 2011

Exogenous stimuli such as nerve growth factor (NGF) exert their effects on neurite outgrowth via Trk neurotrophin receptors. TrkA receptors are known to be ubiquitinated via proteasome inhibition in the presence of NGF. However, the effect of proteasome inhibition on neurite outgrowth has not been studied extensively. To clarify these issues, we investigated signaling events in PC12 cells treated with NGF and the proteasome inhibitor MG132. We found that MG132 facilitated NGF-induced neurite outgrowth and potentiated the phosphorylation of the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) and phosphatidylinositol-3-kinase (PI3K)/AKT pathways and TrkA receptors. MG132 stimulated internalization of surface TrkA receptor and stabilized intracellular TrkA receptor, and the $Ub^{K63}$ chain was found to be essential for stability. These results indicate that the ubiquitin-proteasome system potentiated neurite formation by regulating the stability of TrkA receptors.