MEK1 mRNA Research Articles

MiR-16 Inhibits Extracellular Signal-Regulated Kinases (ERK) Mitogen-Activated Protein Kinases (MAPK) Signaling to Affect Epithelial-Mesenchymal Transition (EMT) and Invasion of Glioma Cells

Abnormal MEK1 expression is associated with tumor cell EMT, invasion and metastasis. Decreased miR-16 level is associated with glioma. Bioinformatics analysis showed a relationship between miR-16 and MEK1. This study assessed whether miR-16 regulates MEK1 expression and affects glioma cell EMT and invasion. The tumor tissues and adjacent glioma tissues were collected to measure miR-16 and MEK1 mRNA. The dual luciferase assay validated the relation of miR-16 with MEK1. U251 cells were cultured and assigned into NC group and mimic group, followed by analysis of cell biological behaviors, and MEK1, p-ERK1/2, E-cadherin, N-Cadherin expression. Compared with adjacent tissues, miR-16 expression was significantly decreased and MEK1 was elevated in glioma tissues. Compared with HEB, miR-16 in glioma U251 and SHG44 cells was decreased and MEK1 was increased. Dual luciferase reporter gene experiments confirmed the relation of miR-16 with MEK1. Transfection of miR-16 mimic significantly down-regulated MEK1, p-ERK1/2 and N-cadherin in U251 cells, upregulated E-cadherin, inhibited cell proliferation, promoted apoptosis, and attenuated EMT and invasion of glioma cells. In conclusion, decreased miR-16 expression and increased MEK1 expression is related to glioma pathogenesis. Overexpression of miR-16 can inhibit MEK1 expression, ERK/MAPK signaling, glioma cell proliferation, promote apoptosis, and attenuate EMT and invasion.

The fibrillin-1 RGD motif posttranscriptionally regulates ERK1/2 signaling and fibroblast proliferation via miR-1208.

Fibrillin-1 is an extracellular matrix protein which contains one conserved RGD integrin-binding motif. It constitutes the backbone of microfibrils in many tissues, and mutations in fibrillin-1 cause various connective tissue disorders. Although it is well established that fibrillin-1 interacts with several RGD-dependent integrins, very little is known about the associated intracellular signaling pathways. Recent published evidence identified a subset of miRNAs regulated by fibrillin-1 RGD-cell adhesion, with miR-1208 among the most downregulated. The present study shows that the downregulated miR-1208 controls fibroblast proliferation. Inhibitor experiments revealed that fibrillin-1 RGD suppressed miR-1208 expression via c-Src kinase and the downstream JNK signaling. Bioinformatic prediction and experimental target sequence validation demonstrated four miR-1208 binding sites on the ERK2 mRNA and one on the MEK1 mRNA. ERK2 and MEK1 are critical proliferation-promoting kinases. Decreased miR-1208 levels elevated the total and phosphorylated ERK1/2 and MEK1/2 protein levels and the phosphorylated to total ERK1/2 ratio. Together, the data demonstrate a novel outside-in signaling mechanism explaining how fibrillin-1 RGD-cell binding regulates fibroblast proliferation.

RAAV9-Mediated MEK1 Gene Expression Restores Post-conditioning Protection Against Ischemia Injury in Hypertrophic Myocardium.

We investigated whether increased expression of activated mitogen-activated protein kinase (MAPK) kinases 1 (MEK1) restores ischemic post-conditioning (IPostC) protection in hypertrophic myocardium following ischemia/reperfusion (I/R) injury. C57Bl/6 mice received recombinant adeno-associated virus type 9 (rAAV9)-mediated activated MEK1 gene delivery systemically, then following the induction of cardiac hypertrophy via transverse aortic constriction for 4weeks. In a Langendorff model, hypertrophic hearts were subjected to 40min/60min I/R or with IPostC intervention consisting of 6cycles of 10s reperfusion and 10s no-flow before a 60-min reperfusion. Hemodynamics, infarct size (IS), myocyte apoptosis and changes in expression of reperfusion injury salvage kinase (RISK) pathway were examined. rAAV9-MEK1 gene delivery led to a 4.3-fold and 2.7-fold increase in MEK1 mRNA and protein expression in the heart versus their control values. I/R resulted in a larger IS in hypertrophic than in non-hypertrophic hearts (52.3 ± 4.7% vs. 40.0 ± 2.5%, P < 0.05). IPostC mediated IS reduction in non-hypertrophic hearts (27.6 ± 2.6%, P < 0.05), while it had no significant effect in hypertrophic hearts (46.5 ± 3.1%, P=NS) compared with the IS in non-hypertrophic or hypertrophic hearts subjected to I/R injury only, respectively. Hemodynamic decline induced by I/R was preserved by IPostC in non-hypertrophic hearts but not in hypertrophic hearts. rAAV9-MEK1 gene delivery restored IPostC protection in hypertrophic hearts evidenced by reduced IS (32.0 ± 2.8% vs. 46.5 ± 3.1%) and cardiac cell apoptosis and largely preserved hemodynamic parameters. These protective effects were associated with significantly increased phosphorylation of ERK1/2 and ribosomal protein S6 kinases (p70S6K), but it had no influence on Akt and glycogen synthase kinase-3β. These results demonstrated that rAAV9-mediated activated MEK1 expression restores IPostC protection in the hypertrophic heart against I/R injury through the activation of ERK pathway.

MiR-195 Enhances the Sensitivity of Oral Cancer Cells to Cisplatin (DDP) by Down-Regulating the Expression of MAPK Kinase 1 (MEK1)

MAPK kinase 1 (MEK1) is involved in the development and cisplatin (DDP) resistance of various tumors. Abnormal miR-195 expression is associated with oral cancer. Bioinformatics analysis revealed a relationship between miR-195 and MEK1. This study investigated whether miR-195 affects oral cancer cells through MEK1. The DDP-resistant cell OSCC-15/DDP was separated into miR-NC group and miR-195 mimic group followed by analysis of the expression of MEK1, p-MEK1 and p-ERK1/2 protein by Western blot, cell apoptosis and proliferation by flow cytometry. MEK1 mRNA is the target gene of miR-195. miR-195 was significantly lower in OSCC-15/DDP cells than OSCC-15 cells and human normal oral epithelial cells (HOEC) cells. MEK1 was significantly upreg-ulated in OSCC-15/DDP cells compared to OSCC-15 cells and HOEC cells. miR-195 mimic significantly elevated miR-195 in OSC-15/DDP cells, downregulated MEK1, p-MEK1 and p-ERK1/2 protein, promoted apoptosis and inhibited cell proliferative ability. miR-195 is related to oral cancer cell DDP resistance and upregulation of miR-195 down-regulates MEK1 expression and reduces DDP resistance.

MiR-16 regulates proliferation and invasion of lung cancer cells via the ERK/MAPK signaling pathway by targeted inhibition of MAPK kinase 1 (MEK1).

ObjectiveThe ERK/MAPK signaling pathway regulates cell proliferation and invasion. MAPK kinase 1 (MEK1) is a protein kinase upstream of ERK that can activate the pathway. Expression of microRNA (miR)-16 in lung cancer tissues is decreased. The aim of this study was to determine roles of miR-16 in proliferation and invasion of lung cancer cells.MethodsWe used a luciferase reporter assay to determine a regulatory relationship between miR-16 and MEK1 and assessed expression of MEK1 in normal lung cells and lung cancer cell lines. Plate cloning, flow cytometry, and Transwell experiments demonstrated the proliferation and invasion ability of cells transfected with wild-type and mutant MEK1.ResultsWe confirmed a regulatory relationship between miR-16 and MEK1 mRNA. Expression of miR-16 was decreased and that of MEK1 and p-ERK1/2 were increased in lung cancer cell lines compared with normal cells. Transfection with miR-101 mimic or small interfering (si)-MEK1 significantly downregulated expression of MEK1 and p-ERK1/2 in Anip973 cells.ConclusionsDecreased miR-16 expression may play a role in upregulating expression of MEK1 and promoting proliferation and invasion of lung cancer cells. Overexpression of miR-16 downregulated the ERK/MAPK pathway by inhibiting MEK1 expression, attenuating clone formation and invasion, and inhibiting cell proliferation.

MiR‑101 regulates the cell proliferation and apoptosis in diffuse large B‑cell lymphoma by targeting MEK1 via regulation of the ERK/MAPK signaling pathway

MAPK kinase1 (MEK1) is an upstream protein kinase of extracellular signal regulated kinase (ERK), which activates the ERK/MAPK (mitogen activated protein kinase) pathway. Importantly, bioinformatic analysis has shown that there is a target complementary binding site between miR‑101 and MEK1. The present study aimed to ascertain whether or not miR‑101 plays a role in regulating MEK1 expression, ERK/MAPK pathway activity, and the proliferation and apoptosis in a diffuse large Bcell lymphoma (DLBCL) cell line. DLBCL tumor samples were collected from patients in our hospital, and lymphatic tissues with reactive lymphoid hyperplasia were selected as controls. The patients were divided into high and low expression groups, and then the survival rate of the two groups was compared using Kaplan‑Meier method, as well the effect of miR‑101 and MEK1 mRNA expression on survival and prognosis was analyzed. The expression of miR‑101, MEK1 and p‑MEK1 between normal lymphoblastic cell lines (HCC1954 BL and NCI‑BL2009) and lymphoma cell lines (SU‑DHL‑4 and Farage) was compared. Lymphoma SU‑DHL‑4 and Farage cells were cultured invitro, and then divided into the following groups: miR‑NC group; miR‑101 mimic group; siRNA‑NC group; and siRNA‑MEK1 group. The expression of miR‑101, MEK1, p‑MEK1, p‑ERK1/2 and Bcl‑2 was compared. Cell apoptosis was detected by flow cytometry, and cell proliferation was detected by EdU staining. The results showed that targeted regulation existed between miR‑101 and MEK1, and the decreased expression of miR‑101 was related to the pathogenesis and prognosis of DLBCL. Upregulation of miR‑101 inhibited DLBCL cell proliferation and facilitated apoptosis by inhibiting the expression of MEK1.

MiR-203 over-expression promotes prostate cancer cell apoptosis and reduces ADM resistance.

Extra-cellular signal regulated kinase (ERK)/mitogen activated protein kinase (MAPK) signaling pathway is widely involved in cell proliferation, apoptosis, and drug resistance. MAPK kinase 1 (MEK1) is the upstream protein kinase of ERK that can activate ERK/MAPK signaling pathway. microRNA 203 (MiR-203) down-regulation is found to be associated with prostate cancer pathogenesis. Bioinformatics analysis showed the complementary targeted relationship between miR-203 and the 3'-UTR of MEK1 mRNA. This study explored the role of miR-203 in regulating prostate cancer cell proliferation, apoptosis, and ADM resistance through affecting MEK1 expression. Dual luciferase assay confirmed the targeted relationship between miR-203 and MEK1. MiR-203, MEK1, p-ERK1/2, and B cell lymphoma 2 (Bcl-2) expressions were compared in normal prostate epithelial cells PrEC, prostate cancer cells PC-3M, and drug resistance cells PC-3M/ADM. PC-3M, PC-3M/ADM cell apoptosis and proliferation were detected by using flow cytometry under ADM treatment at IC50 concentration of PC-3M cells. PC-3M cells were cultured in vitro and divided into four groups, including microRNA-normal control (miR-NC), miR-203 mimic, small interfere NC (si-NC), and si-MEK1. MiR-203 targeted and inhibited MEK1 expression. MiR-203 levels and cell apoptosis were significantly lower, while MEK1, p-ERK1/2, Bcl-2, and cell proliferation were significantly higher in PC-3M/ADM cells compared to the PC-3M cells. MiR-203 mimic and/or si-MEK1 transfection significantly reduced MEK1, p-ERK1/2, and Bcl-2 levels, attenuated cell proliferation, induced cell apoptosis, and decreased drug resistance. MiR-203 elevation suppressed prostate cancer PC-3M cell proliferation, promoted apoptosis, and weakened ADM resistance through targeted inhibiting MEK1 expression to alleviate ERK/MAPK signaling pathway and Bcl-2 expression.

Aldehyde Dehydrogenase 1 (ALDH1) Promotes the Toxicity of TRAIL in Non-Small Cell Lung Cancer Cells via Post-Transcriptional Regulation of MEK-1 Expression

Background/Aim: Tumor Necrosis Factor-Related Apoptosis Inducing Ligand (TRAIL)-based therapies have been used in many human cancers. However, some tumors are resistant to TRAIL-induced cell death. Aldehyde dehydrogenase 1 (ALDH1) is a functional marker for identification of CSCs. Methods: In this study, we used the colony formation assay, AnnexinV/ PI double staining and PI staining to detect proliferation, apoptosis and cell cycle in ALDH1⁺ non-small cell lung cancer (NSCLC) cells with TRAIL treatment. In addition, we established xenograft mouse models to confirm the anti-tumor roles of TRAIL in vivo. Finally, gene array and western blot were used to detect the deeper mechanism of the susceptibility of ALDH1⁺ NSCLC cells to TRAIL. Results: We confirmed that TRAIL could inhibit proliferation, and induce apoptosis and G₁ arrest in ALDH1⁺ NSCLC cells. Correspondingly, TRAIL was associated with decreased tumor size and the favorable survival rate of ALDH1⁺ cells established xenograft mouse models. ALDH1 could increase the death receptors (DR) 4 and DR5 expression in ALDH1⁺ NSCLC cells via activating MEK/ERK signaling pathway. Conclusion: ALDH1 protein induced MEK-1 mRNA stability and promoted its translation via its 3’UTR.

MiR-101 promotes nasopharyngeal carcinoma cell apoptosis through inhibiting Ras/Raf/MEK/ERK signaling pathway.

Extra-cellular signal regulated kinase (ERK)/mitogen activated protein kinase (MAPK) signaling pathway is widely involved in cell proliferation and apoptosis. MAPK kinase 1 (MEK1) is the upstream protein kinase of ERK that can activate ERK/MAPK signaling pathway. microRNA-101 (MiR-101) down-regulation is found to be associated with nasopharyngeal carcinoma (NPC) pathogenesis. Bioinformatics analysis shows the complementary targeted relationship between miR-101 and the 3'-UTR of MEK1 mRNA. This study explores the role of miR-101 in regulating MEK1 expression, ERK/MAPK signaling pathway activation, and NPC pathogenesis. Dual luciferase assay confirmed the targeted relationship between miR-101 and MEK1. MiR-101 and MEK1 expressions were compared in inflammatory nasopharynx tissue and NPC tissue. MiR-101, MEK1, phosphorylated ERK 1/2 (p-ERK1/2), survivin expressions in NP69, CNE-1, HONE1, and C666-2 cell lines were detected. NPC cell line C666-1 was cultured in vitro and divided into four groups, including miR-NC, miR-101, si-NC and si-MEK1. Cell apoptosis was determined by flow cytometry. Cell proliferation was evaluated by EdU staining. MiR-101 targeted inhibited MEK1 expression. MiR-101 was significantly down-regulated, while MEK1 was significantly elevated in NPC tissue compared with inflammatory nasopharynx tissue. MiR-101 was markedly declined, whereas MEK1, p-ERK1/2, and survivin were apparently increased in CNE-1, HONE1, and C666-1 cells compared with NP69 cells. MiR-101 mimic and/or si-MEK1 transfection significantly reduced MEK1, p-ERK1/2, and survivin levels, attenuated cell proliferation, and enhanced cell apoptosis. Down-regulation of miR-101 was related to NPC pathogenesis. MiR-101 elevation suppressed NPC cell proliferation and promoted apoptosis through targeted inhibiting MEK1 expression to alleviate ERK/MAPK signaling pathway and survivin expression.

Significantly decreased mRNA levels of BDNF and MEK1 genes in treatment-resistant depression

The aim of the current study was to investigate whether the levels of mRNA expression of brain-derived neurotrophin factor (BDNF) and a related gene MEK1 were more obviously decreased in treatment-resistant depression (TRD). In total, 50 patients with major depressive disorder (including 26 with TRD and 24 with treatment-responsive depression) and 48 healthy controls were enrolled. BDNF and MEK1 mRNA levels in blood samples from all patients and controls were measured using reverse transcriptase-PCR. BDNF and MEK1 mRNA levels were significantly reduced in patients with major depressive disorder when compared with healthy controls (BDNF: P<0.01; MEK1: P<0.001), as well as among treatment-resistant depressive patients as compared with treatment-responsive depressive patients (BDNF: P<0.001; MEK1: P<0.01). Our findings support the hypothesis that BDNF and MEK1 mRNA expression levels are more obviously decreased in patients with TRD.

Post-transcriptional regulation of MEK-1 by polyamines through the RNA-binding protein HuR modulating intestinal epithelial apoptosis

MEK-1 [MAPK (mitogen-activated protein kinase) kinase-1] is an important signal transducing enzyme that is implicated in many aspects of cellular functions. In the present paper, we report that cellular polyamines regulate MEK-1 expression at the post-transcriptional level through the RNA-binding protein HuR (Hu-antigen R) in IECs (intestinal epithelial cells). Decreasing the levels of cellular polyamines by inhibiting ODC (ornithine decarboxylase) stabilized MEK-1 mRNA and promoted its translation through enhancement of the interaction between HuR and the 3'-untranslated region of MEK-1 mRNA, whereas increasing polyamine levels by ectopic ODC overexpression destabilized the MEK-1 transcript and repressed its translation by reducing the abundance of HuR-MEK-1 mRNA complex; neither intervention changed MEK-1 gene transcription via its promoter. HuR silencing rendered the MEK-1 mRNA unstable and inhibited its translation, thus preventing increases in MEK-1 mRNA and protein in polyamine-deficient cells. Conversely, HuR overexpression increased MEK-1 mRNA stability and promoted its translation. Inhibition of MEK-1 expression by MEK-1 silencing or HuR silencing prevented the increased resistance of polyamine-deficient cells to apoptosis. Moreover, HuR overexpression did not protect against apoptosis if MEK-1 expression was silenced. These results indicate that polyamines destabilize the MEK-1 mRNA and repress its translation by inhibiting the association between HuR and the MEK-1 transcript. Our findings indicate that MEK-1 is a key effector of the HuR-elicited anti-apoptotic programme in IECs.

S1764 Polyamines Regulate the Stability and Translation of MEK-1 mRNA Through RNA-Binding Protein HuR Modulating Apoptosis in Intestinal Epithelial Cells

S1764 Polyamines Regulate the Stability and Translation of MEK-1 mRNA Through RNA-Binding Protein HuR Modulating Apoptosis in Intestinal Epithelial Cells

HOXA1-stimulated oncogenicity is mediated by selective upregulation of components of the p44/42 MAP kinase pathway in human mammary carcinoma cells

Expression of homeobox A1 (HOXA1) results in oncogenic transformation of immortalized human mammary epithelial cells with aggressive tumor formation in vivo. However, the mechanisms by which HOXA1 mediates oncogenic transformation is not well defined. To identify molecules that could potentially be involved in HOXA1-mediated oncogenic transformation, microarray analysis was utilized to characterize and compare the gene expression pattern in response to forced expression or depletion of HOXA1 in human mammary carcinoma cells. Gene expression profiling identified that genes involved in the p44/42 mitogen-activated protein (MAP) kinase activation pathway (GRB2, MAP kinase kinase (MEK1) and SDFR1) or p44/42 MAP kinase-regulated genes (IER3, EPAS1, PCNA and catalase) are downstream expression targets of HOXA1. Forced expression of HOXA1 increased GRB2 and MEK1 mRNA and protein expression and increased p44/42 MAP kinase phosphorylation, activity and Elk-1-mediated transcription. Use of a MEK1 inhibitor demonstrated that increased p44/42 MAP kinase activity is required for the HOXA1-mediated increase in cell proliferation, survival, oncogenicity and oncogenic transformation. Thus, modulation of the p44/42 MAP kinase pathway is one mechanism by which HOXA1 mediates oncogenic transformation of the human mammary epithelial cell.

Gene Response of Human Skin Fibroblasts to Urokinase-and Tissue-Type Plasminogen Activators

In a previous work we have reported evidences on the mitogenic activity of urokinase-type and tissue-type plasminogen activator (u-PA, t-PA) on serum-deprived human dermal fibroblasts. In this work we have studied the transcription-dependent changes of some cell-cycle related genes associated with the biological activity of PAs, as well as the possible involvement of protein tyr kinases (PTK) and/or protein kinase C (PKC) in the mitogenic signal transduction. The data obtained demonstrate that the growth factor activity of PAs is associated with: - a rapid transient activation of early response genes, c-fos, c-jun and c-myc; - the subsequent coordinated down-regulation of p53 and p21CIPI - the constant expression of the MEK1 mRNA in every phase of the cell cycle. Quiescent (G0) cells did not express c-fos, c-jun, c-myc and cyclin A, but upon stimulation with mitogens (fetal calf serum (FCS), u-PA, t-PA) the cyclin A mRNA expression was observed in concomitance with the activation of DNA synthesis.Therefore u-PA, t-PA and FCS similarly modulate the expression of c-fos, c-jun, c-myc, p53, p21CIPI and cyclin A with only slight differences likely related to the time required for activation of DNA synthesis. The PAs mitogenic stimulation of serum-starved cells was associated with the internalization of their molecules, as revealed by immunostaining. The biological activity of u-PA, t-PA, as well as that of limiting concentration of FCS (1%), was mediated by PTK and PKC. Conversely, PTK, but not PKC, was involved in the activation of the proliferative response of basic fibroblast growth factor in the same experimental conditions. In conclusion, u-PA and t-PA can utilize two different pathways, one depending on PTK and the other on PKC in a way similar to the mitogenic activity induced by low concentration of FCS (1%).

Differential long-term regulation of MEK and of p42 MAPK in rat glomerular mesangial cells.

Constitutive stimulation of the mitogen-activated protein kinase (MAPK) activator MAPK/ERK kinase (MEK) is sufficient to promote long-term events such as cell differentiation, proliferation, and transformation. To evaluate a possible mechanism for the chronic regulation of MEK and p42 MAPK, we studied the long-term effects of fetal bovine serum (FBS), the G protein-coupled receptor agonist endothelin-1 (ET-1), and the protein tyrosine kinase-coupled receptor agonist platelet-derived growth factor BB (PDGF BB) on MEK and p42 MAPK in glomerular mesangial cells (GMC). FBS, ET-1, and PDGF BB led to a time-dependent increase in MEK-1 mRNA and protein expression without altering p42 MAPK mRNA and protein levels. FBS also induced MEK-1 mRNA expression in diverse cell types, including NIH/3T3 fibroblasts, A7r5 vascular smooth muscle cells, and Chinese hamster ovary cells. In GMC, cycloheximide inhibited MEK-1 mRNA induction but stimulated p42 MAPK mRNA expression in the absence and presence of FBS, ET-1, or PDGF. The FBS-induced increase in MEK-1 mRNA was accompanied by a sustained enhancement of MEK activity, as assessed by the ability of immunoprecipitated p45 MEK to activate recombinant p42 MAPK and hence phosphorylate myelin basic protein, and p42 MAPK activity. We conclude that, in GMC, MEK-1 acts like a delayed-early gene and that it can be chronically induced at the mRNA and protein level.