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 observe the effect of small interfering RNA (siRNA)-induced MAPK p42 silencing on the survival of HeLa cells.

METHODSTwo siRNAs targeting at the MAPK p42 gene and one random siRNA were synthesized respectively by Silencer siRNA Construction Kit and transfected into HeLa cells by Lipofectamin 2000. The expression of p42(MAPK) in the transfected HeLa cells was analyzed by Western blotting and immunohistochemistry, and the morphology of cells were observed with electron microscope. TUNEL assay and Annexin V/PI staining were employed for detecting the cell apoptosis.

RESULTSThe expression of p42(MAPK) in the HeLa cells was remarkably suppressed after transfection with the two siRNAs, reduced by about 2.5 and 3.2 folds respectively in comparison with the negative control. Chromatin margination in the cell nuclei were observed in the transfected cells, and TUNEL assay and Annexin V/PI staining further confirmed the occurrence of cell apoptosis.

CONCLUSIONIn vitro MAPK p42 siRNA-1 and siRNA-2 transfection can specifically silence the gene expression and induce apoptosis of HeLa cells.

Apoptosis ; physiology ; Gene Silencing ; physiology ; HeLa Cells ; Humans ; Mitogen-Activated Protein Kinase 1 ; biosynthesis ; genetics ; RNA, Small Interfering ; genetics ; Transfection

This work was designed to explore the role of extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathway in migration of bronchial smooth muscle cells (BSMCs) of chronic asthmatic rats. To make chronic asthma model, Wistar rats underwent ovabumin (OVA) injection and eight-week inhalation. BSMCs were cultured in vitro. The expression of ERK1/2 in BSMCs was analyzed by immunocytochemistry, Western blot and RT-PCR. Migration of BSMCs was detected by both plate test and Boyden cell test. Results showed: (1) With Western blot technique, the ratio of p-ERK1/2 to total ERK1/2 in chronic asthmatic group was obviously higher than that in the control group (0.55 +/- 0.05 vs 0.48 +/- 0.04, n=10, P<0.01). (2) With RT-PCR, the relative A values of ERK1 and ERK2 mRNA in airways of chronic asthmatic rats were 1.83 +/- 0.24 and 1.07 +/- 0.11, respectively, which were significantly increased compared with that in the control group (0.58 +/- 0.14 and 0.51 +/- 0.12, n=10, P<0.01). (3) In plate test, the migration of BSMCs of chronic asthmatic rats was 2.9 times of that in the control group and reached 5.0 times by epidermal growth factor (EGF) stimulation, but decreased to 1.7 times by 30 mumol/L PD98059. (4) In Boyden cell test, the migration of BSMCs of chronic asthmatic rats was 1.9 times of that in the control group, and reached 3.1 times by EGF stimulation, but decreased to 1.45 times by 30 mumol/L PD98059. Our results indicate that the migration ability of BSMCs of chronic asthmatic rats increases, and ERK1/2 signaling pathway may play an important role in this process.
Animals ; Asthma ; chemically induced ; physiopathology ; Bronchi ; pathology ; Cell Movement ; physiology ; Cells, Cultured ; Male ; Mitogen-Activated Protein Kinase 1 ; metabolism ; physiology ; Mitogen-Activated Protein Kinase 3 ; metabolism ; physiology ; Myocytes, Smooth Muscle ; pathology ; Ovalbumin ; Rats ; Rats, Wistar ; Signal Transduction ; physiology

BACKGROUNDAbnormal neuronal differentiation plays an important role in central nervous system (CNS) development abnormalities such as Down syndrome (DS), a disorder that results directly from overexpression of genes in trisomic cells. Receptor-interacting protein 140 (RIP140) is significantly upregulated in DS brains, suggesting its involvement in DS CNS development abnormalities. However, the role of RIP140 in neuronal differentiation is still not clear. The current study aimed to investigate the effect of RIP140 overexpression on the differentiation of neuro-2a (N2a) neuroblastoma cells, in vitro.

METHODSStably RIP140-overexpressing N2a (N2a-RIP140) cells were used as a neurodevelopmental model, and were constructed by lipofection and overexpression validated by real-time polymerase chain reaction and Western blot. Retinoic acid (RA) was used to stimulate N2a differentiation. Combining the expression of Tuj1 at the mRNA and protein levels, the percentage of cells baring neurites, and the number of neurites per cell body was semi-quantified to determine the effect of RIP140 on differentiation of N2a cells. Furthermore, western blot and the ERK1/2 inhibitor U0126 were used to identify the specific signaling pathway by which RIP140 induces differentiation of N2a cells. Statistical significance of the differences between groups was determined by one-way analysis of variance followed by the Dunnett test.

RESULTSCompared to untransfected N2a cells RIPl40 expression in N2a-RIP140 cells was remarkably upregulated at both the mRNA and protein levels. N2a-RIP140 cells had a significantly increased percentage of cells baring neurites, and numbers of neurites per cell, as compared to N2a cells, in the absence and presence of RA (P < 0.05). In addition, Tuj1, a neuronal biomarker, was strongly upregulated in N2a-RIP140 cells (P < 0.05) and phosphorylated ERK1/2 (p-ERK1/2) levels in N2a-RIP140 cells were dramatically increased, while differentiation was inhibited by the ERK1/2-specific inhibitor U0126.

CONCLUSIONSRIP140 overexpression promotes N2a cell neuronal differentiation by activating the ERK1/2 pathway.

Blotting, Western ; Cell Differentiation ; physiology ; Cell Line ; Humans ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Neurons ; cytology ; metabolism ; Nuclear Receptor Co-Repressor 1 ; metabolism ; Signal Transduction ; physiology

Fluid shear stress plays an important role in many physiological and pathophysiological processes of the cardiovascular system. It modulates vascular function and structure via stimulating mechanosensitive endothelial cell signal events. Previous studies have identified that the exposure of vascular endothelial cells to fluid mechanical forces can modulate the expressions of many genes, including IL-8 gene. In order to gain an insight into the role of extracellular signal regulated kinase (ERK1/2) signal pathway in the expression of IL-8 mRNA in human umbilical vein endothelial cells (HUVECs) under the stimulation by low shear stress (4.20 dyne/cm2), we employed Western blot to measure phosphorylation of ERK1/2 and used quantitative reversal transcription-polymerase chain reaction (qRT-PCR) to assay the expression of IL-8 mRNA. The results showed: (1) Shear stress could activate ERK1/2 with a rapid, biphasic time course (maximum by 10 min and basal by 2 h); the treatment of HUVECs with Genistein (a highly specific inhibitor of tyrosine protein kinase, TPK) or PD98059 (the inhibitor of mitogen-activated protein/extracellular signal regulated kinase kinase, MEK) culd prevent shear-dependent activation of ERK1/2; (2) When treated with Genistein or PD98059, significant inhibition of IL-8 mRNA expression induced by low shear stress was observed in HUVECs. This in vitro study demonstrates that ERK1/2 plays an important role in IL-8 mRNA expression induced by low shear stress.
Cells, Cultured ; Endothelium, Vascular ; cytology ; metabolism ; Humans ; Interleukin-8 ; biosynthesis ; genetics ; Mitogen-Activated Protein Kinase 1 ; physiology ; Mitogen-Activated Protein Kinase 3 ; physiology ; RNA, Messenger ; biosynthesis ; genetics ; Signal Transduction ; Stress, Mechanical ; Umbilical Veins ; cytology

BACKGROUNDThe role of extracellular signal-regulated kinase 1/2 (ERK1/2) in shikonin-induced HeLa cells apoptosis remains vague. This study was to investigate the activation of caspase pathways and the role of ERK1/2 in human cervical cancer cells, HeLa, by shikonin.

METHODSThe inhibitory effect of shikonin on the growth of HeLa cells was measured by MTT assay. Fluorescent microscopic analysis of apoptotic cells stained with 4',6'-oliiamiclino-2-phenylindole C (DAPI) and Hoechst 33258 was carried out. Caspase-3 and -8 activities were detected using caspase-3 substrate and caspase-8 substrate as substrates, respectively. The protein levels of ERK, p53 and p-ERK were determined by Western blot analysis.

RESULTSShikonin inhibited cell growth in a time- and dose-dependent manner. Caspase-3 and caspase-8 were activated in the apoptotic process and caspase inhibitors effectively reversed shikonin-induced apoptosis. Phosphorylation of ERK resulted in up-regulation of p53 expression, which was blocked by mitogen-activated protein kinase (MEK), inhibitor PD 98059.

CONCLUSIONShikonin induces HeLa cell apoptosis through the ERK, p53 and caspase pathways.

Apoptosis ; drug effects ; Caspases ; physiology ; Cell Proliferation ; drug effects ; DNA Damage ; Flavonoids ; pharmacology ; HeLa Cells ; Humans ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Naphthoquinones ; pharmacology ; Phosphorylation ; Tumor Suppressor Protein p53 ; analysis ; Up-Regulation

To investigate the role of intracellular mitogen activated protein kinase (MAPKs, ERK, JNK and p38) signal pathways in IL-1beta -stimulated alpha-smooth muscle actin (alpha-SMA) expression in rat mesangial cells (rMC), alpha-SMA-promoter gene was transfected into rMC by electro-perforation method and the promoter activity was assayed after IL-1beta (10 ng/ml) stimulation. Protein expression of alpha-SMA was assayed by Western blot. The results were compared between the groups stimulated by IL-1beta with or without PD98059 and SB203580, which are thought to block ERK and p38 pathway, respectively. Dominant-negative-JNKK plasmid was co-transfected in rMC to block JNK pathway. The spatial distribution of alpha-SMA and microfilament-like structure was observed by a confocal laser scanning microscope or an electric microscope. After 6 or 24 h of incubation with IL-1beta, rMC underwent a phenotypic change, which was represented by up-regulation of alpha-SMA promoter activity and protein expression. An increase in alpha-SMA and microfilament-like structure was found around the cell nucleus. Block of JNK and/or p38 pathway greatly inhibited IL-1beta -induced alpha-SMA expression, and the block of p38 pathway also suppressed the basal level of alpha-SMA expression. In contrast, ERK pathway had no influence on the process. It is, therefore, concluded that IL-1beta -stimulated expression of alpha-SMA is due to its protein synthesis and cytoskeleton re-organization in activated rMC. Intracellular signal regulation of alpha-SMA expression seems to be mediated mainly by JNK/p38 pathways, but ERK appears to have no effect on the process.
Actins ; biosynthesis ; Animals ; Cells, Cultured ; Glomerular Mesangium ; metabolism ; Interleukin-1 ; pharmacology ; JNK Mitogen-Activated Protein Kinases ; MAP Kinase Kinase 4 ; MAP Kinase Signaling System ; drug effects ; physiology ; Male ; Mitogen-Activated Protein Kinase Kinases ; drug effects ; physiology ; Mitogen-Activated Protein Kinases ; drug effects ; physiology ; Muscle, Smooth ; metabolism ; Rats ; Rats, Sprague-Dawley

Epidermal keratinocyte differentiation is a tightly regulated stepwise process that requires protein kinase C (PKC) activation. Studies on cultured mouse keraitnocytes induced to differentiate with Ca2+ have indirectly implicated the involvement of PKC alpha isoform. When PKC alpha was overexpressed in undifferentiated keratinocytes using adenoviral system, expressions of differentiation markers such as loricrin, filaggrin, keratin 1 (MK1) and keratin 10 (MK10) were increased, and ERK1/2 phosphorylation was concurrently induced without change of other MAPK such as p38 MAPK and JNK1/2. Similarly, transfection of PKC alphakinase active mutant (PKC alpha- CAT) in the undifferentiated keratinocyte, but not PKC beta-CAT, also increased differentiation marker expressions. On the other hand, PKC alphadominant negative mutant (PKC beta-KR) reduced Ca2+ -mediated differentiation marker expressions, while PKC beta-KR did not, suggesting that PKC alphais responsible for keratinocyte differentiation. When downstream pathway of PKC alphain Ca2+ - mediated differentiation was examined, ERK1/2, p38 MAPK and JNK1/2 phosphorylations were increased by Ca2+ shift. Treatment of keratinocytes with PD98059, MEK inhibitor, and SB20358, p38 MAPK inhibitor, before Ca2+ shift induced morphological changes and reduced expressions of differentiation markers, but treatment with SP60012, JNK1/2 inhibitor, did not change at all. Dominant negative mutants of ERK1/2 and p38 MAPK also inhibited the expressions of differentiation marker expressions in Ca2+ shifted cells. The above results indicate that both ERK1/2 and p38 MAPK may be involved in Ca2+- mediated differentiation, and that only ERK1/2 pathway is specific for PKCa-mediated differentiation in mouse keratinocytes.
Animals ; Calcium/pharmacology/physiology ; Cell Differentiation/physiology ; Intermediate Filament Proteins/analysis/metabolism ; Keratinocytes/cytology/*enzymology ; Membrane Proteins/analysis/metabolism ; Mice ; Mitogen-Activated Protein Kinase 1/*metabolism ; Mitogen-Activated Protein Kinase 3/*metabolism ; Phosphorylation ; Protein Kinase C/genetics/*physiology ; Research Support, Non-U.S. Gov't ; p38 Mitogen-Activated Protein Kinases/metabolism

OBJECTIVETo investigate the effect of cytoskeleton reorganization inhibition with RNA interference on the activation of extracellular signal-regulated kinase (ERK1/2) in primary osteoblasts induced by fluid shear stress (FSS).

METHODSBALB/c mouse primary cultured osteoblasts were isolated by enzyme digestion technique. Osteoblasts were treated with LIM domain kinase 2 (LIM-2) specific siRNA or negative control siRNA, and then were loaded or unloaded by FSS of 1.2 Pa for 0, 5, 15, 30 and 60 min, respectively. The Western blotting was performed to detect the protein expression levels of P-ERK1/2 and ERK1/2, respectively. Two-way ANOVA and one-way ANOVA were used in data analysis.

RESULTSFSS loading for different time (0, 5, 15, 30, 60 min) treated with negative RNA inteference had significant effect on the levels of P-ERK/ERK ratio (0.047 ± 0.031, 0.253 ± 0.137, 0.390 ± 0.155, 0.613 ± 0.123, 0.680 ± 0.108, respectively, P < 0.01). Statistical analysis showed that there was significant interaction between FSS and cytoskeleton reorganization inhibition treated with RNA inteference on the levels of P-ERK/ERK ratio (P < 0.01). The levels of P-ERK/ERK ratio increased when osteoblasts were loaded for 5 - 15 min (0.623 ± 0.129 and 0.623 ± 0.064, respectively, P < 0.05) and returned to baseline at 30 min (0.333 ± 0.086), and then reached the peak at 60 min (0.667 ± 0.064, P < 0.01).

CONCLUSIONSFSS could activate ERK1/2 rapidly in primary cultured osteoblasts. Cytoskeleton reorganization inhibition treated with RNA interference speeded-up the activation of ERK1/2 by FSS, which could increase the sensitivity of ERK1/2 to FSS.

Animals ; Cells, Cultured ; Cytoskeleton ; metabolism ; physiology ; Lim Kinases ; genetics ; metabolism ; Mechanotransduction, Cellular ; Mice ; Mice, Inbred BALB C ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Osteoblasts ; cytology ; enzymology ; Phosphorylation ; RNA Interference ; RNA, Small Interfering ; Stress, Mechanical

BACKGROUNDTransforming growth factor beta (TGF-beta) plays an essential role in the regulation of normal physiologic processes of cells. TGF-beta has been shown to regulate several mitogen-activated protein kinases (MAPK) pathways in several epithelial cells. However, the effects of TGF-beta on soft tissue sarcoma are seldom reported. Our previous studies suggested that there should be some other signal transduction pathways besides Smads, which are important to regulate the growth of human embryonal rhabdomyosarcoma (RMS) cells. In the present study, we examined the expression and functional relations of extracellular signal-regulated kinase 2 (ERK2) and Smad4 in human RMS tissue and a RMS cell line, RD.

METHODSRD cells and normal human primary skeletal myoblasts (Mb) were treated with TGF-beta1 to establish the expression profile of ERK2 at the mRNA and protein levels detected by RT-PCR and immunofluorescence. Immunohistochemistry was used to detect the expression of ERK2 and Smad4 in 50 tissue specimens of human RMS and 23 specimens of normal skeletal muscles. Follow-up of specimens was performed 6 months to 70 months later.

RESULTSRD cells and human RMS tissues showed the higher expression of ERK2 and Smad4 than the normal control, either the protein level or the mRNA level. And, exogenous TGF-beta1 stimulation can lead to higher expression of ERK2 and its nuclear translocation, so TGF-beta1 can also activated MAPK (ERK2) pathway, resulting in a sustained activation of ERK2 for at least 2 hours. Immunohistochemistry analysis, however, showed that there was no correlation between ERK2 and Smad4 protein. The overexpression of ERK2 and Smad4 had no indicative effects on histological subtypes, histological grading, gender, age, and prognosis.

CONCLUSIONSIn RMS, signaling of TGF-beta1 from cell surface to nucleus can also be directed through the MAPK (ERK2) pathway besides the TGF-beta1/Smads pathway. The activation of ERK2 by TGF-beta1 may be Smad4 independent. Moreover, there may be some other tanglesome relationships between the TGF-beta1/Smads pathway and the MAPK pathway which takes part in the development, invasion and metastasis of tumor cells.

Cells, Cultured ; Humans ; Mitogen-Activated Protein Kinase 1 ; physiology ; Muscle, Skeletal ; metabolism ; RNA, Messenger ; analysis ; Rhabdomyosarcoma ; metabolism ; Signal Transduction ; Smad4 Protein ; physiology ; Transforming Growth Factor beta1 ; pharmacology