OBJECTIVETo study the role of mitogen-activated protein kinase (MAPK) pathway in the action mechanism of PYM-induced KB cell apoptosis.

METHODSWestern blot analysis was used to investigate the expression of the mitogen-activated protein kinase.

RESULTSWhen treated with PYM in cultured KB cells, the extracellular signal-regulated kinase (ERKl/2) showed a dose-and time-dependent decreasing in phosphorylation status of these proteins through a western blot analysis, whereas protein levels of p38 MAPK remained unchanged.

CONCLUSIONSThe mitogen-activated protein kinase (MAPK) pathway may play an important ro1e in PYM-induced apoptosis of KB cells.

Antibiotics, Antineoplastic ; pharmacology ; Apoptosis ; drug effects ; Bleomycin ; analogs & derivatives ; pharmacology ; Humans ; KB Cells ; Mitogen-Activated Protein Kinases ; physiology ; p38 Mitogen-Activated Protein Kinases

To study the effect of cholecystokinin-octapeptide (CCK-8) on systemic hypotension and cytokine production in serum and lung of endotoxic shock (ES) rats induced by lipopolysaccharide (LPS) and investigate its signal transduction mechanism of p38 mitogen-activated protein kinase (MAPK), the changes in mean arterial pressure (MAP) were observed by using a polygraph in four groups of SD rats: group of LPS (8 mg/kg i.v.) induced ES, group of CCK-8 (40 microg/kg i.v.) pretreatment 10 min before LPS (8 mg/kg) administration, group of CCK-8 (40 microg/kg i.v.) only, and normal saline (control) group; the contents of proinflammatory cytokines (TNF-alpha, IL-1 beta and IL-6) in the lung and serum were assayed using ELISA kits; and p38 MAPK was detected by Western blot. The results showed that CCK-8 alleviated LPS-induced decrease in MAP of rats; compared with the control, LPS elevated the levels of TNF-alpha, IL-1 beta and IL-6 in serum and lung significantly, while CCK-8 significantly inhibited the LPS-induced increases in TNF-alpha, IL-1 beta and IL-6 in serum and lung. The activation of p38 MAPK in the lung of ES rats was enhanced by CCK-8 pretreatment. These results suggest that CCK-8 can alleviate the LPS-induced decrease in MAP of ES rats and exert an inhibitory effect on the overproduction of proinflammatory cytokines, and that p38 MAPK may be involved in its signal transduction mechanisms.
Animals ; Cytokines ; biosynthesis ; Lung ; metabolism ; Male ; Mitogen-Activated Protein Kinases ; biosynthesis ; physiology ; Rats ; Rats, Sprague-Dawley ; Shock, Septic ; drug therapy ; metabolism ; Sincalide ; pharmacology ; p38 Mitogen-Activated Protein Kinases

OBJECTIVETo investigate the MEK and ERK expression and their relationship with clinicopathological parameters in human breast carcinoma, and the effect of preoperative chemotherapy on MEK and ERK protein expression.

METHODSSamples were obtained from 56 patients with breast carcinoma and 8 patients with benign tumors. Sixteen of the 56 patients received preoperative chemotherapy. Western blot and immunohistochemistry were used to measure the expression of MEK1, MEK2 and ERK1, ERK2 protein.

RESULTSMEK2 and ERK1, ERK2 protein levels were increased in breast carcinoma tissue compared with those in adjacent normal tissues (t = 7.244, 5.959, 3.735, P < 0.01) and benign tumors (t = 2.206, P < 0.05). The levels of MEK1 were decreased. The expression of MEK2 protein in ER negative patients was higher than that in ER positive ones. MEK2 protein levels were lower in patients who received preoperative chemotherapy than in those who did not.

CONCLUSIONOverexpression of MEK-ERK may play an important role in the development of human breast carcinoma. MEK and ERK protein expressions are inhibited by preoperative chemotherapy.

Adult ; Aged ; Blotting, Western ; Breast Neoplasms ; diagnosis ; enzymology ; metabolism ; Female ; Humans ; Immunohistochemistry ; MAP Kinase Kinase 1 ; MAP Kinase Kinase 2 ; MAP Kinase Signaling System ; physiology ; Middle Aged ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; Mitogen-Activated Protein Kinase Kinases ; metabolism ; Mitogen-Activated Protein Kinases ; metabolism ; Prognosis ; Protein Kinases ; metabolism ; Protein-Serine-Threonine Kinases ; metabolism ; Protein-Tyrosine Kinases ; metabolism

OBJECTIVETo investigate the signaling pathway through testing the effects of dexamethasone (Dex) on the activation of the extracellular signal-regulated protein kinase 1/2 (ERK1/2) and p38 kinase (p38) in HO-8910 cells.

METHODSActivation of the ERK1/2 and p38 was detected by Western blotting using the antibodies against the total ERK1/2 and p38 mitogen-activated protein kinases (MAPKs) protein and the phosphorylated forms of them.

RESULTSDex could suppress the activation of ERK1/2, while enhance the activation of p38 rapidly and strongly in a dose- and time- dependent manner. Neither effect could be blocked by RU486, the antagonist of glucocorticoid receptor (GR).

CONCLUSIONDex has rapid effects on the activation of ERK1/2 and p38, and these effects are not mediated by GR.

Cell Division ; physiology ; Dexamethasone ; pharmacology ; Enzyme Activation ; Female ; Glucocorticoids ; pharmacology ; Humans ; Mitogen-Activated Protein Kinase 3 ; Mitogen-Activated Protein Kinases ; metabolism ; Ovarian Neoplasms ; enzymology ; pathology ; Signal Transduction ; Tumor Cells, Cultured ; p38 Mitogen-Activated Protein Kinases

BACKGROUNDAdrenomedullin (ADM), a potent hypotensive small peptide, was recently found to inhibit the proliferation of glomerular mesangial cells (MsC) in vitro and to attenuate glomerular lesions in vivo, however the mechanisms remain poorly understood. In this study, we attempted to elucidate them using molecular signal transduction.

METHODSCultured rat MsC were treated with ADM and several inhibitors of signalling molecules. Methyl thiazoleterazolium (MTT) assay and BrdU incorporation method were employed for examining MsC proliferation. Western blot analysis was used for detecting total mitogen activated protein kinases (t-MAPKs) and phosphorylated MAPKs (p-MAPKs) proteins.

RESULTSADM suppressed MsC proliferation in a concentration- and time-dependent fashion. This response was inhibited by ADM receptor antagonist CGRP8-37 and a potent protein kinase-A (PKA) inhibitor, H89. Forskolin, a direct adenylate cyclase activator, also significantly inhibited MsC proliferation. SB203580, a P38MAPK inhibitor, and U0126, a MEK inhibitor, both completely blocked ADM mediated responses in MsC. However, curcumin, a SAPK/JNK inhibitor, and GF109203X, a potent protein kinase-C (PKC) inhibitor, had no effect on MsC growth. Western blot analysis showed that ADM did not change the expression of t-MAPKs but increased p-SAPK/JNK and p-P38MAPK levels and decreased p-ERK level. These responses were inhibited by CGRP8-37. All these kinase phosphorylations, except for the increase in p-SAPK/JNK, could be stimulated using forskolin. In addition, only ADM mediated changes in ERK and P38MAPK phosphorylations were inhibited by H89. GF109203X did not affect ADM induced changes in three p-MAPKs expressions.

CONCLUSIONSADM inhibits MsC proliferation possibly through cAMP-PKA pathway. Both phosphorylations of ERK and P38MAPK pathways were necessary in mediating the antiproliferative response of ADM. It does not preclude the involvement of cAMP independent pathways in the ADM mediated responses.

Adrenomedullin ; Animals ; Cell Proliferation ; drug effects ; Cells, Cultured ; Extracellular Signal-Regulated MAP Kinases ; physiology ; Glomerular Mesangium ; cytology ; drug effects ; JNK Mitogen-Activated Protein Kinases ; physiology ; Peptides ; pharmacology ; Rats ; Signal Transduction ; physiology ; p38 Mitogen-Activated Protein Kinases ; physiology

Hydrogen sulfide (H(2)S) is among a family of endogenous molecules of gas, defined as gasotransmitters. In recent years, endogenous production of H(2)S and its physiological importance have been realized. Abnormal metabolism and functions of H(2)S contribute to or participate in the pathogenesis of many diseases. This article reviews recent discoveries on the roles of H(2)S in the regulation of cell proliferation and apoptosis. The molecular mechanisms for the cellular effects of H(2)S are also recapitulated, including changes in mitogen-activated protein kinase, cell cycle-related kinase, cell death-related gene and ion channels. A better understanding of H(2)S-regualted cell growth or death will pave way for future design of novel pharmacological and therapeutic interventions for various diseases.
Animals ; Apoptosis ; physiology ; Cell Proliferation ; Cyclin-Dependent Kinases ; metabolism ; Humans ; Hydrogen Sulfide ; metabolism ; Mitogen-Activated Protein Kinases ; metabolism

OBJECTIVETo investigate the effects of mitogen activated protein kinase (MAPK) signal transduction pathways on heat shock protein 70 (HSP70) gene expression in endothelial cells exposed to benzo(a)pryene (BaP).

METHODSPorcine aortic endothelial cells were pre-treated or by PD98059 (10 micro mol/L) or SB203580 (20 micro mol/L) for 1 hour, then treated with different concentrations of BaP (0, 0.1, 0.5, 1.0, 5.0 and 10.0 micro mol/L) for 24 hours respectively;Expression levels of three phosphorylated MAPKs [extracellular signal regulated protein kinase (ERK), c-Jun amino-terminal kinase (JNK), and p38] and HSP70 were determined by Western-blot.

RESULTSThe three phosphorylated MAPKs expressional levels especially p-ERK1 had different extents of changes with dose-response relationship under BaP exposure. BaP inhibited the expression of HSP70, which significantly decreased in medium and high dose group (>or= 1.0 micro mol/L) but did not decrease in control group (P < 0.05). Although the inhibitor of ERK (PD98059) could partly weaken the inhibited effects of BaP on HSP70 expression, HSP70 expression levels of endothelial cells pre-treated with PD98059 were still significantly lower than that of control cells (P < 0.05).

CONCLUSIONERK1 pathway might play some roles in HSP70 gene expression in endothelial cells exposed to BaP, and other unknown signal pathways might also have some effects on this process.

Animals ; Benzo(a)pyrene ; toxicity ; Blotting, Western ; Dose-Response Relationship, Drug ; Endothelial Cells ; drug effects ; metabolism ; Enzyme Inhibitors ; pharmacology ; Flavonoids ; pharmacology ; HSP70 Heat-Shock Proteins ; analysis ; Imidazoles ; pharmacology ; JNK Mitogen-Activated Protein Kinases ; MAP Kinase Kinase 4 ; Mitogen-Activated Protein Kinase Kinases ; analysis ; Mitogen-Activated Protein Kinases ; analysis ; antagonists & inhibitors ; Pyridines ; pharmacology ; Signal Transduction ; physiology ; Swine ; p38 Mitogen-Activated Protein Kinases

Penile erection is regulated by the relaxation of corpus cavernosum smooth muscle cells (CCSMCs). It has been recognized that the Ras/MEK/ERK1/2 signaling pathway is closely related to the functions of CCSMCs and endothelial cells, and it is involved in the regulation of penile erection, mainly via phosphorylation of NO synthase. ERK1/2 phosphorylates, inhibits eNOS activity, and thus reduces the relaxation of CCSMCs and penile erection. But the site of phosphorylation is not yet clear. In CCSMCs and endothelial cells, the ERK1/2 pathway interacts with other cascades and regulates the erectile function of the penis. This article presents an overview of the researches on the ERK1/2 signaling cascade, its regulatory role and its interaction with other signaling pathways in penile erection.
Humans ; Male ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Penile Erection ; physiology ; Penis ; metabolism ; physiology ; Signal Transduction ; raf Kinases ; metabolism

Calreticulin (CRT), an important Ca(2+)-binding molecular chaperone in the endoplasmic reticulum (ER), and caspase-12, a pivotal molecule mediating ER-initiated apoptosis, are involved in the ER stress (ERS). Using primary cultured neonatal cardiomyocytes, CRT and caspase-12 expression and activation during hypoxic preconditioning (HPC) and hypoxia/reoxygenation (H/R) were studied to explore the role of ERS in cardioprotection by HPC. And by using SB203580 and SP600125 [the specific inhibitors of p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK)] separately, the role of p38 MAPK in HPC-induced ERS was also detected. Neonatal cardiomyocytes were prepared from Sprague-Dawley rats aged 24 h, and cultured in DMEM medium containing 10% fetal bovine serum, and then randomly divided into six groups as follows: H/R, HPC+H/R, SB203580+HPC+H/R, SP600125+HPC+H/R, HPC and control groups. H/R was produced by 2-hour hypoxia/14-hour reoxygenation, and HPC by 20-minute hypoxia/24-hour reoxygenation. Morphological studies, estimation of lactate dehydrogenase (LDH) leakage and flow cytometry were employed to assess cell apoptosis and necrosis. CRT and caspase-12 expression and activation, levels of phospho-p38 MAPK and phospho-JNK were detected by Western blot. All experiments were repeated at least four separate times. The results obtained are as follows: (1) HPC relieved the cell injury caused by H/R. Compared with that in H/R group, cellso survival rate in HPC+H/R group increased by 6.4%, and the apoptosis rate and LDH leakage in the cell culture medium decreased by 6.6% and 70.0%, respectively. (2) H/R induced caspase-12 activation (33.2-fold increase in comparison with control) and CRT expression (8.1-fold increase in comparison with control). HPC itself resulted in mild CRT up-regulation (2.6-fold increase in comparison with control), but the extent of up-regulation was lower than that induced by H/R. HPC before H/R was found to relieve the over-expression of CRT induced by H/R (72.4% decrease), and to inhibit the activation of caspase-12 (59.6% decrease). (3) The protection of HPC and HPC-induced up-expression of CRT and inhibition of caspase-12 activation were almost eliminated when the inhibitor of p38 MAPK, not of JNK, was present before HPC. These results suggest that HPC protects the neonatal cardiomyocytes from severe ERS-induced apoptosis during sustained H/R through pre-invoking proper ERS response. Mild up-expression of CRT and inhibition of caspase-12 activation induced by HPC, which are important protection factors, are mediated by p38 MAPK, not by JNK.
Animals ; Caspase 12 ; physiology ; Cell Hypoxia ; Cytoprotection ; Endoplasmic Reticulum ; metabolism ; Ischemic Preconditioning, Myocardial ; JNK Mitogen-Activated Protein Kinases ; metabolism ; Rats ; Rats, Sprague-Dawley ; p38 Mitogen-Activated Protein Kinases ; physiology

OBJECTIVETo study the effect of Rac-MEKK-JNK (Rac-mitogen activated protein kinase kinase kinase-C-jun N-terminal protein kinase) signal pathway on heat shock-induced hsp90 beta gene expression and the impact of Hsp90 on the regulation of the pathway.

METHODSDN-Rac, DN-MEKK or DN-JNK were cotransfected with hsp90 beta CAT reporter plasmid beta 3.1 into Jurkat or LETPa-2 cells individually, the CAT mRNA expression was then determined quantitatively by competitive RT-PCR based system. Western blot was carried out to detect the expression level and phosphorylation of c-Jun in Jurkat and LETPa-2 cells that were transfected with DN-Rac, DN-MEKK or DN-JNK. By in vitro kinase activity assay and Western blot, the effect of geldnamycin (GA) on heat induced JNK activity were evaluated.

RESULTSIn Jurkat cell transfected with DN-Rac, DN-MEKK or DN-JNK, heat shock induced relative CAT mRNA expression level was decreased to (72.8 +/- 5)%, (60 +/- 13.2)% and (47.7 +/- 12.1)% of the control respectively; while in LETPa-2 cell hsp90 beta 3.1 reporter gene expression was accordingly suppressed to (16.17 +/- 5.1)%, (50.2 +/- 8.7)% and (47.5 +/- 10)% of control. C-Jun expression and phosphorylation were inhibited by the transfection of either one of DN-Rac, DN-MEKK or DN-JNK. With GA treatment, heat shock induced JNK activity was repressed, while the expression level of JNK or c-Jun was not obviously changed.

CONCLUSIONSRac-MEKK-JNK pathway promotes heat shock induced hsp90 beta gene expression and hsp90 may participate in the regulation of heat shock activated Rac-MEKK-JNK signal pathway in both Jurkat and LETPa-2 cells.

Benzoquinones ; Cell Line, Tumor ; Genes, Reporter ; HSP90 Heat-Shock Proteins ; biosynthesis ; genetics ; Hot Temperature ; Humans ; JNK Mitogen-Activated Protein Kinases ; Lactams, Macrocyclic ; Leukemia, T-Cell ; pathology ; Mitogen-Activated Protein Kinase Kinases ; physiology ; Mitogen-Activated Protein Kinases ; physiology ; Protein Kinase C ; physiology ; Quinones ; pharmacology ; Signal Transduction ; Transfection