• Molecules and Cells
• /
• 제38권7호
• /
• pp.604-609
• /
• 2015

The active metabolite of vitamin D such as $1{\alpha}$,25-dihydroxyvitamin ($D_3(1{\alpha},25(OH)_2D_3)$ is a well-known key regulatory factor in bone metabolism. However, little is known about the potential of vitamin D as an odontogenic inducer in human dental pulp cells (HDPCs) in vitro. The purpose of this study was to evaluate the effect of vitamin $D_3$ metabolite, $1{\alpha},25(OH)_2D_3$, on odontoblastic differentiation in HDPCs. HDPCs extracted from maxillary supernumerary incisors and third molars were directly cultured with $1{\alpha},25(OH)_2D_3$ in the absence of differentiation-inducing factors. Treatment of HDPCs with $1{\alpha},25(OH)_2D_3$ at a concentration of 10 nM or 100 nM significantly upregulated the expression of dentin sialophosphoprotein (DSPP) and dentin matrix protein1 (DMP1), the odontogenesis-related genes. Also, $1{\alpha},25(OH)_2D_3$ enhanced the alkaline phosphatase (ALP) activity and mineralization in HDPCs. In addition, $1{\alpha},25(OH)_2D_3$ induced activation of extracellular signal-regulated kinases (ERKs), whereas the ERK inhibitor U0126 ameliorated the upregulation of DSPP and DMP1 and reduced the mineralization enhanced by $1{\alpha},25(OH)_2D_3$. These results demonstrated that $1{\alpha},25(OH)_2D_3$ promoted odontoblastic differentiation of HDPCs via modulating ERK activation.

• Molecules and Cells
• /
• 제41권3호
• /
• pp.188-197
• /
• 2018

Benzidine, a known carcinogen, is closely associated with the development of bladder cancer (BC). Epithelial-mesenchymal transition (EMT) is a critical pathophysiological process in BC progression. The underlying molecular mechanisms of mitogen-activated protein kinase (MAPK) pathway, especially extracellular regulated protein kinases 5 (ERK5), in regulating benzidine-induced EMT remains unclarified. Hence, two human bladder cell lines, T24 and EJ, were utilized in our study. Briefly, cell migration was assessed by wound healing assay, and cell invasion was determined by Transwell assay. Quantitative PCR and western blot were utilized to determine both gene expressions as well as protein levels of EMT and MAPK, respectively. Small interfering RNA (siRNA) was transfected to further determine ERK5 function. As a result, the migration and invasion abilities were enhanced, epithelial marker expression was decreased while mesenchymal marker expression was increased in human BC cell lines. Meanwhile, benzidine administration led to activation of ERK5 and activator protein 1 (AP-1) proteins, without effective stimulation of the Jun N-terminal kinase (JNK) or p38 pathways. Moreover, Benzidine-induced EMT and ERK5 activation were completely suppressed by XMD8-92 and siRNAs specific to ERK5. Of note, ERK1/2 was activated in benzidine-treated T24 cells, while benzidine-induced EMT could not be reversed by U0126, an ERK1/2 inhibitor, as indicated by further study. Collectively, our findings revealed that ERK5-mediated EMT was critically involved in benzidine-correlated BC progression, indicating the therapeutic significance of ERK5 in benzidine-related BC.

• Asian Pacific Journal of Cancer Prevention
• /
• 제13권4호
• /
• pp.1505-1510
• /
• 2012

To aim of this was to observe emodin-mediated cytotoxicity and its influence on Rad51 and ERCC1 expressionin non-small cell lung cancer (NSCLC). NSCLC cells were cultured in vitro with emodin at various concentrations (0, 25, 50, 75 and $100\;{\mu}mol/L$) for 48h and the proliferation inhibition rate was determined by the MTT method. Then, NSCLC were treated with emodin (SK-MES-1 $40\;{\mu}mol/L$, A549 $70\;{\mu}mol/L$) or $20\;{\mu}mol/L$ U0126 (an ERK inhibitor) for 48 h, or with various concentrations of emodin for 48 h and the protein and mRNA expressions of ERCC1 and Rad51 were determined by RT-PCR and Western blot assay, respectively. Emodin exerted a suppressive effect on the proliferation of NSCLC in a concentration dependent manner. Protein and mRNA expression of ERCC1 and Rad51 was also significantly decreased with the dose. Vacuolar degeneration was observed in A549 and SK-MES-1 cell lines after emodin treatment by transmission electron microscopy. Emodin may thus inhibited cell proliferation in NSCLC cells by downregulation ERCC1 and Rad51.

• Biomolecules & Therapeutics
• /
• 제21권1호
• /
• pp.42-48
• /
• 2013

Nystatin, a polyene antifungal antibiotic, is a cholesterol sequestering agent. The antifungal agent alters composition of the plasma membrane of eukaryotic cells, whereas its effects on cells are poorly investigated. In the current study, we investigated the question of whether nystatin was able to induce expression of macrophage inflammatory protein-1 (MIP-1). THP-1 cells rarely express MIP-$1{\alpha}$ and MIP-$1{\beta}$, however, upon exposure to nystatin, significantly elevated expression of MIP-$1{\alpha}$ and MIP-$1{\beta}$ was observed in a dose-dependent fashion at the messenger and protein levels. Cellular factors activated by nystatin as well as involved in nystatin-induced expression of MIP-1 proteins were identified in order to understand the molecular mechanisms of action of the anti-fungal agent. Treatment with nystatin resulted in enhanced phosphorylation of Akt, ERK, p38 MAPK, and JNK. Abrogation or significant attenuation of nystatin-induced expression of MIP-$1{\alpha}$ and MIP-$1{\beta}$ was observed by treatment with Akt inhibitor IV, LY294002, and SP6001250. Inhibition of ERK or p38MAPK using U0126 and SB202190 did not lead to attenuation of MIP-1 expression. In addition, inhibitors of protein kinase C, such as GF109203X and Ro-318220, also attenuated expression of MIP-1. These results indicate that nystatin is able to activate multiple cellular kinases and, among them, Akt and JNK play primary roles in nystatin-induced expression of MIP-1 proteins.

• Molecules and Cells
• /
• 제39권10호
• /
• pp.742-749
• /
• 2016

The cancer chemo-preventive effects of equol have been demonstrated for a wide variety of experimental tumours. In a previous study, we found that equol inhibited proliferation and induced apoptotic death of human gastric cancer MGC-803 cells. However, the mechanisms underlying equol-mediated apoptosis have not been well understood. In the present study, the dual AO (acridine orange)/EB (ethidium bromide) fluorescent assay, the comet assay, MTS, western blotting and flow cytometric assays were performed to further investigate the pro-apoptotic effect of equol and its associated mechanisms in MGC-803 cells. The results demonstrated that equol induced an apoptotic nuclear morphology revealed by AO/EB staining, the presence of a comet tail, the cleavage of caspase-3 and PARP and the depletion of cIAP1, indicating its pro-apoptotic effect. In addition, equol-induced apoptosis involves the mitochondria-dependent cell-death pathway, evidenced by the depolarization of the mitochondrial membrane potential, the cleavage of caspase-9 and the depletion of Bcl-xL and full-length Bid. Moreover, treating MGC-803 cells with equol induced the sustained activation of extracellular signal-regulated kinase (ERK), and inhibiting ERK by U0126, a MEK/ERK pathway inhibitor, significantly attenuated the equol-induced cell apoptosis. These results suggest that equol induces mitochondria-dependent apoptosis in human gastric cancer MGC-803 cells via the sustained activation of the ERK1/2 pathway. Therefore, equol may be a novel candidate for the chemoprevention and therapy of gastric cancer.

• International Journal of Oral Biology
• /
• 제30권3호
• /
• pp.85-90
• /
• 2005

Homeostatic pH is very important for various cellular processes, including metabolism, survival, and death. An imbalanced-pH might induce cellular acidosis, which is involved in many abnormal events such as apoptosis and malignancy. One of several factors contributing to the onset of metabolic acidosis is the production of lactate and protons by lactate dehydrogenase (LDH) in anaerobic glycolysis. LDH is an important enzyme that catalyzes the reversible conversion of pyruvate to lactate. This study sought to examine whether decreases in extracellular pH induce apoptosis of CHO cells, and to elucidate the role of mitogen-activated protein kinases (MAPKs) in acidification-induced apoptosis. To test apoptotic signaling by acidification we used CHO dhfr cells that were sensitive to acidification, and CHO/anti-LDH cells that are resistant to acidification-induced apoptosis and have reduced LDH activity by stable LDH antisense mRNA expression. In the present study, cellular lactic acid-induced acidification and the role of MAPKs signaling in acidification-induced apoptosis were investigated. Acidification, which is caused by $HCO{_3}^-$-free conditions, induced apoptosis and MAPKs (ERK, JNK, and p38) activation. However, MAPKs were slightly activated in acidic conditions in the CHO/anti-LDH cells, indicating that lactic acid-induced acidification induces activation of MAPKs. Treatment with a p38 inhibitor, PD169316, increased acidification-induced apoptosis but apoptosis was not affected by inhibitors for ERK (U0126) or JNK (SP600125). Thus, these data support the hypothesis that activation of the p38 MAPK during acidification-induced apoptosis contributes to cell survival.

• Molecules and Cells
• /
• 제21권2호
• /
• pp.237-243
• /
• 2006

Brain-derived neurotrophic factor (BDNF) is a neuromodulator of nociceptive responses in the dorsal root ganglia (DRG) and spinal cord. BDNF synthesis increases in response to nerve growth factor (NGF) in trkA-expressing small and medium-sized DRG neurons after inflammation. Previously we demonstrated differential activation of multiple BDNF promoters in the DRG following peripheral nerve injury and inflammation. Using reporter constructs containing individual promoter regions, we investigated the effect of NGF on the multiple BDNF promoters, and the signaling pathway by which NGF activates these promoters in PC12 cells. Although all the promoters were activated 2.4-7.1-fold by NGF treatment, promoter IV gave the greatest induction. The p38 mitogen-activated protein kinase (MAPK) inhibitor, SB203580, phosphatidylinositol 3-kinase (PI-3K) inhibitor, LY294003, protein kinase A (PKA) inhibitor, H89, and protein kinase C (PKC) inhibitor, chelerythrine, had no effect on activation of promoter IV by NGF. However, activation was completely abolished by the MAPK kinase (MEK) inhibitors, U0126 and PD98059. In addition, these inhibitors blocked NGF-induced phosphorylation of extracellular signal-regulated protein kinase (ERK) 1/2. Taken together, these results suggest that the ERK1/2 pathway activates BDNF promoter IV in response to NGF independently of NGF-activated signaling pathways involving PKA and PKC.

• Molecules and Cells
• /
• 제38권2호
• /
• pp.145-150
• /
• 2015

Continuous intra- and extracellular stresses induce disorder of $Ca^{2+}$ homeostasis and accumulation of unfolded protein in the endoplasmic reticulum (ER), which results in ER stress. Severe long-term ER stress triggers apoptosis signaling pathways, resulting in cell death. Neural epidermal growth factor-like like protein 2 (NELL2) has been reported to be important in protection of cells from cell death-inducing environments. In this study, we investigated the cytoprotective effect of NELL2 in the context of ER stress induced by thapsigargin, a strong ER stress inducer, in Cos7 cells. Overexpression of NELL2 prevented ER stress-mediated apoptosis by decreasing expression of ER stress-induced C/EBP homologous protein (CHOP) and increasing ER chaperones. In this context, expression of anti-apoptotic Bcl-xL was increased by NELL2, whereas NELL2 decreased expression of pro-apoptotic proteins, such as cleaved caspases 3 and 7. This anti-apoptotic effect of NELL2 is likely mediated by extracellular signal-regulated kinase (ERK) signaling, because its inhibitor, U0126, inhibited effects of NELL2 on the expression of anti- and pro-apoptotic proteins and on the protection from ER stress-induced cell death.

• Molecules and Cells
• /
• 제40권1호
• /
• pp.17-23
• /
• 2017

Mitogen-activated protein kinase (MAPK) signaling cascades play critical roles in various cellular events in plants, including stress responses, innate immunity, hormone signaling, and cell specificity. MAPK-mediated stress signaling is also known to negatively regulate nitrogen-fixing symbiotic interactions, but the molecular mechanism of the MAPK signaling cascades underlying the symbiotic nodule development remains largely unknown. We show that the MtMKK5-MtMPK3/6 signaling module negatively regulates the early symbiotic nodule formation, probably upstream of ERN1 (ERF Required for Nodulation 1) and NSP1 (Nod factor Signaling Pathway 1) in Medicago truncatula. The overexpression of MtMKK5 stimulated stress and defense signaling pathways but also reduced nodule formation in M. truncatula roots. Conversely, a MAPK specific inhibitor, U0126, enhanced nodule formation and the expression of an early nodulation marker gene, MtNIN. We found that MtMKK5 directly activates MtMPK3/6 by phosphorylating the TEY motif within the activation loop and that the MtMPK3/6 proteins physically interact with the early nodulation-related transcription factors ERN1 and NSP1. These data suggest that the stress signaling-mediated MtMKK5/MtMPK3/6 module suppresses symbiotic nodule development via the action of early nodulation transcription factors.

• The Korean Journal of Physiology and Pharmacology
• /
• 제16권6호
• /
• pp.447-453
• /
• 2012

TLR6 forms a heterodimer with TLR2 and TLR4. While proinflammatory roles of TLR2 and TLR4 are well documented, the role of TLR6 in inflammation is poorly understood. In order to understand mechanisms of action of TLR6 in inflammatory responses, we investigated the effects of FSL-1, the TLR6 ligand, on expression of chemokine CCL2 and cytokine IL-$1{\beta}$ and determined cellular factors involved in FSL-1-mediated expression of CCL2 and IL-$1{\beta}$ in mononuclear cells. Exposure of human monocytic leukemia THP-1 cells to FSL-1 resulted not only in enhanced secretion of CCL2 and IL-$1{\beta}$, but also profound induction of their gene transcripts. Expression of CCL2 was abrogated by treatment with OxPAPC, a TLR-2/4 inhibitor, while treatment with OxPAPC resulted in partially inhibited expression of IL-$1{\beta}$. Treatment with FSL-1 resulted in enhanced phosphorylation of Akt and mitogen-activated protein kinases and activation of protein kinase C. Treatment with pharmacological inhibitors, including SB202190, SP6001250, U0126, Akt inhibitor IV, LY294002, GF109203X, and RO318220 resulted in significantly attenuated FSL-1-mediated upregulation of CCL2 and IL-$1{\beta}$. Our results indicate that activation of TLR6 will trigger inflammatory responses by upregulating expression of CCL2 and IL-$1{\beta}$ via TLR-2/4, protein kinase C, PI3K-Akt, and mitogen-activated protein kinases.