Extracellular signal regulated kinase 5 promotes cell migration, invasion and lung metastasis in a FAK-dependent manner

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

Effect of Bmi-1 on Multidrug Resistance in K562/ADR Cells and Its Mechanisms / 中国实验血液学杂志

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.

The Pharmacological Inhibition of ERK5 Enhances Apoptosis in Acute Myeloid Leukemia Cells

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.

MicroRNA-143 inhibits cell growth by targeting ERK5 and MAP3K7 in breast cancer

This study aimed to investigate the function and mechanism of microRNA-143 (miR-143) in the occurrence and development of breast cancer (BC). A total of 30 BC tissues, 30 corresponding noncancerous tissues, and 10 normal control (NC) breast tissues were obtained to detect the levels of miR-143, extracellular signal-regulated kinase 5 (ERK5) and mitogen-activated protein 3 kinase 7 (MAP3K7) using RT-qPCR, western blotting or immunohistochemistry. The correlation of miR-143 with ERK5 or MAP3K7 was evaluated using Pearson correlation analysis. MCF-7 cells were transiently transfected with miR-143 mimic, miR-143 inhibitor, miR-143 mimic/inhibitor + si-ERK5, si-MAP3K7 or si-cyclin D1. Then, cell growth was evaluated by MTT assay and the expressions of phospho-ERK5 (p-ERK5), ERK5, p-MAP3K7, MAP3K7 and cyclin D1 were detected by western blotting. Results showed that, compared with noncancerous tissues or NC breast tissues, miR-143 level was decreased, while p-ERK5, ERK5, p-MAP3K7 and MAP3K7 expressions were increased in BC tissues (all P<0.01). The miR-143 level was negatively correlated with the mRNA level of ERK5 or MAP3K7 (r=-4.231 or r=-4.280, P<0.01). In addition, up-regulated miR-143 significantly decreased the expressions of p-ERK5, ERK5, p-MAP3K7, MAP3K7 and cyclin D1 (all P<0.01), as well as cell viability in MCF-7 cells (all P<0.05) while the effect of down-regulated miR-143 was the opposite. In conclusion, both ERK5 and MAP3K7 may be the target genes of miR-143. Increased expression of miR-143 can inhibit cell growth, which may be associated with ERK5 and MAP3K7 expressions in BC.

6 Paths of ERK5 signaling pathway regulate hepatocyte proliferation in rat liver regeneration.

Generally, extra-cellular-signal-regulated kinase 5 (ERK5) signaling pathway regulates many physiological activities, such as cell proliferation and cell differentiation. However, little is known about how ERK5 signaling pathway composed of 15 paths participates in regulating hepatocyte proliferation during liver regeneration (LR). In this study, to explore the influence ERK5 signaling pathway upon hepatocytes at gene transcription level, rat genome 230 2.0 array was used to detect expression changes of 75 related genes in isolated hepatocytes from rat regenerating liver. Bioinformatics and systems biology methods were applied to analyze the precise role of ERK5 signaling pathway in regulating hepatocyte proliferation during LR. Results showed that 62 genes were contained in the array and 22 genes were significantly changed. It was found that 6 paths were related to hepatocyte proliferation during rat LR. Among them, paths 3, 6 and 13 of ERK5 signaling pathway modulated cell cycle progression by decreasing the negative influence on ERK5 and paths 3, 4, 8 and 9 by reinforcing the positive influence on ERK5. In summary, the study shows that 22 genes and 6 paths of ERK5 signaling pathway participate in regulating proliferation of hepatocytes in rat LR.

Role of extracellular signal-regulated protein kinase 5 in the biosynthesis of follicle-stimulating hormone-stimulated progesterone in primary granulosa cells / 中国医学科学院学报

<p><b>OBJECTIVE</b>To 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.</p><p><b>METHODS</b>The 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.</p><p><b>RESULTS</b>ERK5 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.</p><p><b>CONCLUSION</b>ERK5 may stimulate FSH-mediated progesterone production in primary cultured granulosa cells.</p>

Laminar flow activation of ERK5 leads to cytoprotective effect via CHIP-mediated p53 ubiquitination in endothelial cells / 대한해부학회지

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.

Expression of ERK5 in multidrug-resistant hepatocellular carcinoma cell line / 南方医科大学学报

<p><b>OBJECTIVE</b>To 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.</p><p><b>METHODS</b>MTT 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.</p><p><b>RESULTS</b>The 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.</p><p><b>CONCLUSIONS</b>ERK5 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.</p>

Gene expression of extracellular-signal regulated protein kinase 5 and their MAPKK in fetal skin hypertrophic scars / 中华整形外科杂志

<p><b>OBJECTIVE</b>To 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.</p><p><b>METHODS</b>After 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).</p><p><b>RESULTS</b>In 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).</p><p><b>CONCLUSION</b>ERKS 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.</p>