Atherosclerosis is readily observed in areas where disturbed flow is formed, while the atheroprotective region is found in areas with steady laminar flow (L-flow). It has been established that L-flow protects endothelial cells against endothelial dysfunction, including apoptosis and inflammation. It has also been reported that extracellular signal-regulated kinase 5 (ERK5) regulated endothelial integrity and protected endothelial cells from vascular dysfunction and disease under L-flow. However, the molecular mechanism by which L-flow-induced ERK5 activation inhibits endothelial apoptosis has not yet been determined. Transcription factor p53 is a major pro-apoptotic factor which contributes to apoptosis in various cell types. In this study, we found that 15-deoxy-Delta(12,14)-prostaglandin J2 induced p53 expression and that endothelial apoptosis was reduced under the L-flow condition. This anti-apoptotic response was reversed by the biochemical inhibition of ERK5 activation. It was also found that activation of ERK5 protected endothelial apoptosis in a C terminus of Hsc70-interacting protein (CHIP) ubiquitin ligase-dependent manner. Moreover, molecular interaction between ERK5-CHIP and p53 ubiquitination were addressed with a CHIP ubiquitin ligase activity assay. Taken together, our data suggest that the ERK5-CHIP signal module elicited by L-flow plays an important role in the anti-apoptotic mechanism in endothelial cells.
Apoptosis ; Atherosclerosis ; Endothelial Cells ; Inflammation ; Mitogen-Activated Protein Kinase 7 ; Prostaglandin D2 ; Transcription Factors ; Ubiquitin ; Ubiquitination

OBJECTIVE: To investigate the effect of Bmi-1 gene silencing on drug resistance of leukemia cell K562/ADR and to explore its possible mechanism. METHODS: After two sequences of Bmi-1-siRNA were transfected into drug-resistant K562/ADR cells, the mRNA and protein expressions of Bmi-1 gene were detected. After Bmi-1 gene silencing the expression of P-gp and MDR1 were detected and the accumulation of doxorubicin in K562/ADR cells were detected by flow cytometry to determine the effect of Bmi-1 gene silencing on drug resistance of K562/ADR cells. The protein expression of NF-κB was analyzed after Bmi-1 gene silencing. Then after K562/ADR cells were treated with NF-κB inhibitor PDTC, the protein expression of P-gp and its functional changes were analyzed to determine the effect of NF-κB on drug resistance of leukemia cells. The protein expressions of PTEN, AKT and p-AKT after Bmi-1 gene silencing were detected and the effect of Bmi-1 gene silencing on PTEN/PI3K/AKT signaling pathway in drug-resistant cells was determined. After K562/ADR cells were treated with PI3K/AKT pathway inhibitor LY294002, the protein expressions of NF-κB and P-gp were analyzed to determine the regulation of AKT on the expression of NF-κB and P-gp. The protein expressions of AKT, p-AKT, NF-κB and P-gp were detected after the Bmi-1-siRNA transfected cells were treated by PTEN inhibitor BPV. Above-mentioned expression of mRNA was detected by RT-PCR, and the protein expression was detected by Western blot. RESULTS: The expression of Bmi-1 gene in K562/ADR cells decreased at both mRNA and protein levels and the doxorubicin accumulation increased after Bmi-1 gene silencing. The expression of MDR1/P-gp in Bmi-1-siRNA transfected cells was lower than that in K562/ADR cells (P＜0.05). After Bmi-1 gene silencing, the activity of NF-κB decreased. The activity of NF-κB and P-gp expression was inhibited and the function of P-gp in K562/ADR cells was reduced by using NF-κB inhibitor (PDTC). The protein expression of PTEN increased while the protein expression of p-AKT decreased after Bmi-1 gene silencing (P＜0.05). The protein expressions of p-AKT, P-gp and the activity of NF-κB were inhibited significantly by using PI3K/AKT inhibitor LY294002 (P＜0.05). After the Bmi-1-siRNA transfected cells were treated by PTEN inhibitor BPV, the activity of NF-κB and the protein expressions of P-gp were restored. CONCLUSION Bmi-1 plays a key role in MDR-mediated multidrug resistance in K562/ADR cells, which may be mediated by activating PTEN/AKT pathway to regulate NF-κB.
Doxorubicin ; Drug Resistance, Multiple ; Drug Resistance, Neoplasm ; Humans ; K562 Cells ; Mitogen-Activated Protein Kinase 7

OBJECTIVETo study the role of extracellular signal-regulated protein kinase 5 (ERK5) during the biosynthesis of follicle-stimulating hormone (FSH)-mediated progesterone in primary granulosa cells.

METHODSThe expressions of phosphorylated and general forms of ERKS in primary granulosa cells after the treatment of FSH were detected by Western blot analysis. The subcellular localization of ERK5 was observed by confocal microscopy. The effect of ERK5 on FSH-mediated progesterone biosynthesis in primary granulosa cells was analyzed using recombinant adenovirus vectors.

RESULTSERK5 activation was induced by FSH in a time-dependent manner in primary cultured granulosa cells, although the general ERK5 protein level decreased also in a time-dependent manner. The treatment of FSH showed no remarkable effect on the subcellular distribution of endogenous ERK5, which was mainly in the cytoplasm of granulosa cells. The co-infection of Ad-caMEK5 and Ad-wtERK5 increased the progesterone production and StAR expression in primary cultured granulosa cells, whereas inhibition of ERK5 activation suppressed the FSH-stimulated progesterone production.

CONCLUSIONERK5 may stimulate FSH-mediated progesterone production in primary cultured granulosa cells.

Animals ; Cells, Cultured ; Female ; Follicle Stimulating Hormone ; pharmacology ; Granulosa Cells ; drug effects ; metabolism ; Mitogen-Activated Protein Kinase 7 ; metabolism ; physiology ; Progesterone ; biosynthesis ; Rats ; Rats, Sprague-Dawley

This study was designed to evaluate ERK5 expression in lung cancer and malignant melanoma progression and to ascertain the involvement of ERK5 signaling in lung cancer and melanoma. We show that ERK5 expression is abundant in human lung cancer samples, and elevated ERK5 expression in lung cancer was linked to the acquisition of increased metastatic and invasive potential. Importantly, we observed a significant correlation between ERK5 activity and FAK expression and its phosphorylation at the Ser
A549 Cells ; Animals ; Cell Movement ; Epithelial-Mesenchymal Transition/genetics* ; Focal Adhesion Kinase 1/metabolism* ; Humans ; Lung Neoplasms/pathology* ; MAP Kinase Signaling System ; Mice ; Mitogen-Activated Protein Kinase 7/metabolism* ; Neoplasm Invasiveness ; Neoplasm Metastasis ; Neoplasm Proteins/metabolism*

OBJECTIVETo explore the change of gene expression of extracellular-signal regulated protein kinase 5 (ERK5) and its upstream signaling molecule (MEK5) in fetal skin of differentially developmental stages and hypertrophic scars.

METHODSAfter morphological characteristics of skin of different developmental stages and hypertrophic scars were detected with pathological methods, gene expression of ERK5 and MEK5 was examined with reverse transcription-polymerase chain reaction analysis (RT-PCR).

RESULTSIn early gestational fetal skin, genes of ERK5 and MEK5 were strongly expressed, while in late gestational skin and children skin, the expression of ERK5 and MEK5 was apparently decreased (P < 0.05). In normal skin, the level of gene expression of ERK5 was lower. In proliferative hypertrophic scars, mRNA content of this gene was apparently increased. In mature scars, the content of this gene transcript was 3.2 times the normal skin. In contrast, the levels of MEK5 transcript in normal skin and hypertrophic scars of various phases showed no substantial changes (P > 0.05).

CONCLUSIONERKS medicating signaling pathway might be involved in regulating cutaneous development at the embryonic stage and determining cutaneous structure ad function. The increase of gene transcription of ERK5 and MEK5 in younger fetal skin might be a reason for rapid proliferation of the skin cells and scraless healing of skin. The activation of ERK5 gene expression in hypertrophic scars versus normal skin might be one of the mechanisms controlling the formation of hypertrophic scars, in which the role of MEK5 needed to be further studied.

Child ; Child, Preschool ; Cicatrix, Hypertrophic ; enzymology ; genetics ; Fetus ; Gene Expression Regulation, Developmental ; Gene Expression Regulation, Enzymologic ; Gestational Age ; Humans ; Mitogen-Activated Protein Kinase 7 ; genetics ; Mitogen-Activated Protein Kinase Kinases ; genetics ; RNA, Messenger ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Skin ; embryology ; metabolism ; pathology

OBJECTIVETo detect the expression of extracellular-signal regulated protein kinase 5 (ERK5) in multidrug-resistant hepatocellular carcinoma cell lines hepG2/ADM and BEL-7402/5-FU and in the parental cell lines (hepG2 and BEL-7402), and study the role of ERK5 in multidrug resistance of hepatocellular carcinoma.

METHODSMTT assay was used to determine the multidrug resistance (MDR) of hepG2/ADM and BEL-7402/5-FU cells. Real-time PCR and Western blotting were used to detect the expression of ERK5 at mRNA and protein levels in the 4 cell lines.

RESULTSThe resistance indices to ADM, 5-FU, and CDDP was 12.34, 5.74, and 3.81 in hepG2/ADM cells, and the resistance indices to 5-FU, VCR, OHP, MTX, and ADM was 15.32, 10.08, 5. 85, 6.74 and 3.26 in BEL-7402 cells, respectively. Compared with those in hepG2 and BEL-7402 cells, the ERK5 gene was up-regulated at both mRNA and protein levels in HepG2/ADM cells, but down-regulated at the mRNA level and up-regulated at the protein level in BEL-7402/5-FU cells.

CONCLUSIONSERK5 is related to multidrug resistance in HepG2/ADM and BEL-7402/5-FU cells, and may provide new clues for reversing multidrug resistance of hepatocellular carcinoma cells.

Carcinoma, Hepatocellular ; metabolism ; pathology ; Doxorubicin ; pharmacology ; Drug Resistance, Multiple ; Drug Resistance, Neoplasm ; Fluorouracil ; pharmacology ; Humans ; Liver Neoplasms ; metabolism ; pathology ; Mitogen-Activated Protein Kinase 7 ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Tumor Cells, Cultured

BACKGROUNDClaudin-6 is a protein component of tight junctions and its expression could downregulate the malignant phenotype of breast carcinoma. Here we investigated the mechanisms of claudin-6 induced human MCF-7 breast cancer cells apoptosis, invasion, and migration.

METHODSTerminal deoxyribonucleotide transferase-mediated nick-end labeling assay and Annexin-V/PI double stain assay were carried out to evaluate apoptosis. Inhibitors of each pathway were used to inactivate the signaling pathways. The expression of claudin-6 and phosphate p38, Erk 1/2 and Akt protein levels was confirmed by Western blotting analysis. Invasive and migratory traits of claudin-6 expressing cells were determined by Boyden chamber invasion assay and monolayer wound-healing assay.

RESULTSCells with high-level expression of claudin-6 had a higher rate of apoptosis than control cells. Western blotting assay showed that by contrast to control groups, p38 pathways were more activated in claudin-6 expressing cells. However, after inhibitor SB203580 treatment, the activation status could be significantly counteracted. Furthermore, by applying inhibitors to the apoptotic rate, invasive and migratory traits were also recovered in cells with claudin-6 expression.

CONCLUSIONClaudin-6 may function through p38 mitogen-activated protein kinase pathway, of which inhibition may reverse claudin-6-induced cell apoptosis, invasion, and migration.

Apoptosis ; genetics ; physiology ; Blotting, Western ; Cell Movement ; genetics ; physiology ; Claudins ; genetics ; metabolism ; Humans ; In Situ Nick-End Labeling ; MAP Kinase Signaling System ; genetics ; physiology ; MCF-7 Cells ; p38 Mitogen-Activated Protein Kinases ; genetics ; metabolism

Acute myeloid leukemia (AML) is a fatal hematological malignancy which is resistant to a variety of chemotherapy drugs. Extracellular signal-regulated kinase 5 (ERK5) plays a novel role in chemoresistance in some cancer cells and this pathway is a central mediator of cell survival and apoptotic regulation. The aim of this study was to investigate the effect of ERK5 inhibitor, XMD8-92, on proliferation and apoptosis in AML cell lines. Findings showed that XMD8-92 inhibited the activation of ERK5 by G-CSF and decreased the expression of c-Myc and Cyclin D1. The treatment of XMD8-92 reduced the phosphorylation of ERK5 leading to a distinct inhibition of cell proliferation and increased apoptosis in Kasumi-1 and HL-60 cells. Taken together, our study suggests that the inhibition of ERK5 by XMD8-92 can trigger apoptosis and inhibit proliferation in AMLs. Therefore, the inhibition of ERK5 may be an effective adjuvant in AML chemotherapy.
Apoptosis ; Cell Cycle ; Cell Line ; Cell Proliferation ; Cell Survival ; Cyclin D1 ; Drug Therapy ; Granulocyte Colony-Stimulating Factor ; Hematologic Neoplasms ; HL-60 Cells ; Humans ; Leukemia, Myeloid, Acute ; Mitogen-Activated Protein Kinase 7 ; Phosphorylation

OBJECTIVETo investigate the effect of diallyl disulfide (DADS) on invasion and metastasis of human breast cancer MCF-7 cells and explore the possible mechanism.

METHODSMCF-7 cells treated with 100, 200, and 400 µmol/L of DADS for 24 h were examined for cell invasion and migration capacities using Transwell assay and wound healing assay, respectively. The protein expression of E-cadherin, vimentin, MMP-9 and p-p38 in the cells were detected with Western blotting. The effect of transforming growth factor-β1 (TGF-β1) as the agonist of p38 activity was tested in antagonizing the effects of DADS.

RESULTSDADS inhibited the invasion and migration of MCF-7 cells in a dose-dependent manner, down-regulated the protein expression of Vimentin and MMP-9 and up-regulated E-cadherin expression in the cells. Treatment with TGF-β1 to up-regulate p38 activity obviously antagonized the inhibitory effect of DADS on the invasion and metastasis of MCF-7 cells.

CONCLUSIONDADS can inhibit the invasion and metastasis of MCF-7 cells in vitro by down-regulating p38 activity.

Allyl Compounds ; pharmacology ; Breast Neoplasms ; pathology ; Cadherins ; metabolism ; Disulfides ; pharmacology ; Gene Expression Regulation, Neoplastic ; Humans ; MAP Kinase Signaling System ; drug effects ; MCF-7 Cells ; drug effects ; Matrix Metalloproteinase 9 ; metabolism ; Mitogen-Activated Protein Kinase 11 ; metabolism ; Neoplasm Invasiveness ; Neoplasm Metastasis ; Transforming Growth Factor beta1 ; pharmacology ; Vimentin ; metabolism