Micropeptide AF127577.4-ORF hidden in a lncRNA diminishes glioblastoma cell proliferation via the modulation of ERK2/METTL3 interaction.

Micropeptides hidden in long non-coding RNAs (lncRNAs) have been uncovered to program various cell-biological changes associated with malignant transformation-glioblastoma (GBM) cascade. Here, we identified and characterized a novel hidden micropeptide implicated in GBM. We screened potential candidate lncRNAs by establishing a workflow involving ribosome-bound lncRNAs, publicly available MS/MS data, and prognosis-related lncRNAs. Micropeptide expression was detected by western blot (WB), immunofluorescence (IF), and immunohistochemistry (IHC). Cell proliferation rate was assessed by calcein/PI staining and EdU assay. Proteins interacted with the micropeptide were analyzed by proteomics after co-immunoprecipitation (Co-IP). We discovered that lncRNA AF127577.4 indeed encoded an endogenous micropeptide, named AF127577.4-ORF. AF127577.4-ORF was associated with GBM clinical grade. In vitro, AF127577.4-ORF could suppress GBM cell proliferation. Moreover, AF127577.4-ORF reduced m6A methylation level of GBM cells. Mechanistically, AF127577.4-ORF diminished ERK2 interaction with m6A reader methyltransferase like 3 (METTL3) and downregulated phosphorylated ERK (p-ERK) level. The ERK inhibitor reduced p-ERK level and downregulated METTL3 protein expression. AF127577.4-ORF weakened the stability of METTL3 protein by ERK. Also, AF127577.4-ORF suppressed GBM cell proliferation via METTL3. Our study identifies a novel micropeptide AF127577.4-ORF hidden in a lncRNA, with a potent anti-proliferating function in GBM by diminishing METTL3 protein stability by reducing the ERK2/METTL3 interaction. This micropeptide may be beneficial for development of therapeutic strategies against GBM.

ALOX15B controls macrophage cholesterol homeostasis via lipid peroxidation, ERK1/2 and SREBP2.

Macrophage cholesterol homeostasis is crucial for health and disease and has been linked to the lipid-peroxidizing enzyme arachidonate 15-lipoxygenase type B (ALOX15B), albeit molecular mechanisms remain obscure. We performed global transcriptome and immunofluorescence analysis in ALOX15B-silenced primary human macrophages and observed a reduction of nuclear sterol regulatory element-binding protein (SREBP) 2, the master transcription factor of cellular cholesterol biosynthesis. Consequently, SREBP2-target gene expression was reduced as were the sterol biosynthetic intermediates desmosterol and lathosterol as well as 25- and 27-hydroxycholesterol. Mechanistically, suppression of ALOX15B reduced lipid peroxidation in primary human macrophages and thereby attenuated activation of mitogen-activated protein kinase ERK1/2, which lowered SREBP2 abundance and activity. Low nuclear SREBP2 rendered both, ALOX15B-silenced and ERK1/2-inhibited macrophages refractory to SREBP2 activation upon blocking the NPC intracellular cholesterol transporter 1. These studies suggest a regulatory mechanism controlling macrophage cholesterol homeostasis based on ALOX15B-mediated lipid peroxidation and concomitant ERK1/2 activation.

Antitumor activity of extracellular signal-regulated kinases 1/2 inhibitor BVD-523 (ulixertinib) on thyroid cancer cells.

OBJECTIVE: This study aimed to investigate BVD-523 (ulixertinib), an adenosine triphosphate (ATP)-dependent extracellular signal-regulated kinases 1/2 inhibitor, for its antitumor potential in thyroid cancer. MATERIALS AND METHODS: Ten thyroid cancer cell lines known to carry mitogen-activated protein kinase (MAPK)-activated mutations, including v-Raf murine sarcoma viral oncogene homolog B (BRAF) and rat sarcoma virus (RAS) mutations, were examined. Cells were exposed to a 10-fold concentration gradient ranging from 0 to 3000 nM for 5 days. The half-inhibitory concentration was determined using the Cell Counting Kit-8 assay. Following BVD-523 treatment, cell cycle analysis was conducted using flow cytometry. In addition, the impact of BVD-523 on extracellular signal-regulated kinase (ERK)- dependent ribosomal S6 kinase (RSK) activation and the expression of cell cycle markers were assessed through western blot analysis. RESULTS: BVD-523 significantly inhibited thyroid cancer cell proliferation and induced G1/S cell cycle arrest dose-dependently. Notably, cell lines carrying MAPK mutations, especially those with the BRAF V600E mutation, exhibited heightened sensitivity to BVD-523's antitumor effects. Furthermore, BVD-523 suppressed cyclin D1 and phosphorylated retinoblastoma protein expression, and it robustly increased p27 levels in an RSK-independent manner. CONCLUSION: This study reveals the potent antitumor activity of BVD-523 against thyroid cancer cells bearing MAPK-activating mutations, offering promise for treating aggressive forms of thyroid cancer.

Inhibition of HSP20 Ameliorates Steatotic Liver Disease by Stimulating ERK2-Dependent Autophagy.

HSP20 emerges as a novel regulator of autophagy in the heart. Nonetheless, the detailed function of HSP20 in the liver and its effect on autophagy remain unknown. Here, we observed that HSP20 expression is increased in liver tissues from mice and patients with metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as nonalcoholic fatty liver disease. Liver-specific downregulation of HSP20 mitigates hepatic steatosis and insulin resistance in obese mice, while upregulating HSP20 promotes lipid deposition and hepatocyte cell death. Mechanistically, liquid chromatography-tandem mass spectrometry revealed that HSP20 interacts with phosphorylated extracellular regulated protein kinase 2 (ERK2) and prevents its dephosphorylation by dual specificity phosphatase 6, leading to ERK2-mediated repression of autophagy and resulting in aggravated saturated fatty acid (SFA)-triggered hepatocyte death. Importantly, such adverse effects could be ameliorated by ERK inhibitor. Our data reveal a framework of how HSP20 increases susceptibility of SFA-induced liver injury through enhancing ERK2 phosphorylation, which represents a plausible therapeutic intervention to combat MASLD.

Circ-LDLRAD3/miR-655-3p/MAPK1 axis enhances cell migration and invasion in papillary thyroid carcinoma.

Papillary thyroid carcinoma (PTC) is a prevalent histological subtype of thyroid cancer, whose occurrence and development may be related to circRNA dysregulation. This research proposed to unravel circ-LDLRAD3-related mechanisms in PTC. First, circ-LDLRAD3, miR-655-3p .and MAPK1 levels in PTC were quantitatively measured. Then, plasmid vectors or oligonucleotides that interfere with circ-LDLRAD3, miR-655-3p, or MAPK1 were transfected into PTC cells, followed by the analysis of proliferation, apoptosis, migration, and invasion. Finally, the targeted binding sites between miR-655-3p and circ-LDLRAD3 or MAPK1 were predicted by starBase and experimentally verified. Statistically, PTC samples expressed high circ-LDLRAD3 and MAPK1 and low miR-655-3p. Knocking down circ-LDLRAD3 or enhancing miR-655-3p hindered PTC cell proliferation, migration, and invasion, and forced apoptosis. circ-LDLRAD3 bound to miR-655-3p to affect MAPK1 expression. Elevating MAPK1 rescued circ-LDLRAD3 knockdown-allowed obstruction of PTC cell growth. In conclusion, circ-LDLRAD3 stimulates PTC development by releasing miR-655-3p-targeted MAPK1.

Expression and promoter methylation of mitogen-activated protein kinase 1 in tumor and marginal cells of breast cancer.

AIM: In the present study, we sought to explore potential differences in the expression and promoter methylation of mitogen-activated protein kinase 1 (MAPK1) between tumor and marginal cells of breast cancer lesions. METHODS: A total of 50 randomly selected patients with breast cancer (BCa) undergoing needle biopsy were enrolled. Clinical specimens containing both tumor and marginal cells were collected and preserved. After DNA extraction using specific primers, MAPK1 mRNA and promoter methylation were measured with spectrophotometry at 260/280 nm absorption wavelengths. To deliver a comparative analysis, data from The Cancer Genome Atlas (TCGA) program regarding breast cancer (BRCA), were downloaded from Xena Functional Genomics Explorer and separately analyzed. The suitability of MAPK1 expression and promoter methylation as biomarkers for BCa was analyzed with receiver operating characteristic (ROC) curves. RESULTS: We found a positive correlation between tumor stage and MAPK1 expression (P-value: 0.029) in BCa. Likewise, MAPK1 expression was significantly associated with lymph node metastasis (P-value: 0.018). There was a significant difference in the expression of MAPK1 mRNA between tumor and marginal cells of BCa and BRCA (P-value < 0.001). However, we did not find any statistically significant difference in MAPK1 promoter methylation between tumor and marginal cells of both BCa and BRCA. With an area under the curve (AUC) of 0.71, the diagnostic accuracy of MAPK1 expression in BCa and BRCA was validated. However, MAPK1 promoter methylation was not found to be a suitable biomarker. CONCLUSION: Our findings suggest that while MAPK1 expression, might be a promising biomarker for evaluating oncogenic activity in patients suspected of BCa. We were not able to detect a prognostic/diagnostic role for MAPK1 promoter methylation.

LncRNA HCG27 Promotes Glucose Uptake Ability of HUVECs by MiR-378a-3p/MAPK1 Pathway.

OBJECTIVE: Gestational diabetes mellitus (GDM) is the most common metabolic disorder during pregnancy. LncRNA HLA complex group 27 (HCG27) plays a crucial role in various metabolic diseases. However, the relationship between lncRNA HCG27 and GDM is not clear. This study aimed to verify a competing endogenous RNA (ceRNA) interaction regulation axis of miR-378a-3p/mitogen-activated protein kinase 1 (MAPK1) regulated by HCG27 in GDM. METHODS: LncRNA HCG27 and miR-378a-3p were detected by RT-qPCR. The expression of MAPK1 in umbilical vein endothelial cells (HUVECs) was detected by RT-qPCR and that in the placenta by Western blotting. To explore the relationship among lncRNA HCG27, miR-378a-3p, MAPK1 and the glucose uptake ability of HUVECs, vector HCG27, si-HCG27, miR-378a-3p mimic and inhibitor were transfected to achieve overexpression and inhibition of HCG27 or miR-378a-3p. The interaction between miR-378a-3p and lncRNA HCG27 or MAPK1 was confirmed by the dual-luciferase reporter assay. Besides, glucose consumption by HUVECs was detected by the glucose assay kit. RESULTS: HCG27 expression was significantly decreased in both the placenta and primary umbilical vein endothelial cells, while the expression of miR-378a-3p was significantly increased in GDM tissues, and the expression of MAPK1 was decreased in GDM tissues. This ceRNA interaction regulation axis was proved to affect the glucose uptake function of HUVECs. The transfection of si-HCG27 could significantly reduce the expression of the MAPK1 protein. If the MAPK1 overexpression plasmid was transfected simultaneously with si-HCG27 transfection, the reduced glucose uptake in HUVECs resulting from the decrease in lncRNA HCG27 was reversed. MiR-378a-3p mimic can significantly reduce the mRNA expression of MAPK1 in HUVECs, whereas miR-378a-3p inhibitor can significantly increase the mRNA expression of MAPK1. The inhibition of miR-378a-3p could restore the decreased glucose uptake of HUVECs treated with si-HCG27. Besides, overexpression of lncRNA HCG27 could restore the glucose uptake ability of the palmitic acid-induced insulin resistance model of HUVECs to normal. CONCLUSION: LncRNA HCG27 promotes glucose uptake of HUVECs by miR-378a-3p/MAPK1 pathway, which may provide potential therapeutic targets for GDM. Besides, the fetal umbilical cord blood and umbilical vein endothelial cells collected from pregnant women with GDM after delivery could be used to detect the presence of adverse molecular markers of metabolic memory, so as to provide guidance for predicting the risk of cardiovascular diseases and health screening of offspring.

A conserved arginine within the αC-helix of Erk1/2 is a latch of autoactivation and of oncogenic capabilities.

Eukaryotic protein kinases (EPKs) adopt an active conformation following phosphorylation of a particular activation loop residue. Most EPKs spontaneously autophosphorylate this residue. While structure-function relationships of the active conformation are essentially understood, those of the "prone-to-autophosphorylate" conformation are unclear. Here, we propose that a site within the αC-helix of EPKs, occupied by Arg in the mitogen-activated protein kinase (MAPK) Erk1/2 (Arg84/65), impacts spontaneous autophosphorylation. MAPKs lack spontaneous autoactivation, but we found that converting Arg84/65 of Erk1/2 to various residues enables spontaneous autophosphorylation. Furthermore, Erk1 molecules mutated in Arg84 are oncogenic. Arg84/65 thus obstructs the adoption of the "prone-to-autophosphorylate" conformation. All MAPKs harbor an Arg that is equivalent to Arg84/65 of Erks, whereas Arg is rarely found at the equivalent position in other EPKs. We observed that Arg84/65 of Erk1/2 interacts with the DFG motif, suggesting that autophosphorylation may be inhibited by the Arg84/65-DFG interactions. Erk1/2s mutated in Arg84/65 autophosphorylate not only the TEY motif, known as critical for catalysis, but also on Thr207/188. Our MS/MS analysis revealed that a large proportion of the Erk2R65H population is phosphorylated on Thr188 or on Tyr185 + Thr188, and a small fraction is phosphorylated on the TEY motif. No molecules phosphorylated on Thr183 + Thr188 were detected. Thus, phosphorylation of Thr183 and Thr188 is mutually exclusive suggesting that not only TEY-phosphorylated molecules are active but perhaps also those phosphorylated on Tyr185 + Thr188. The effect of mutating Arg84/65 may mimic a physiological scenario in which allosteric effectors cause Erk1/2 activation by autophosphorylation.

ERK2 Mutations Affect Interactions, Localization, and Dimerization.

The most frequent ERK2 (MAPK1) mutation in cancers, E322K, lies in the common docking (CD) site, which binds short motifs made up of basic and hydrophobic residues present in the activators MEK1 (MAP2K1) and MEK2 (MAP2K2), in dual specificity phosphatases (DUSPs) that inactivate the kinases, and in many of their substrates. Also, part of the CD site, but mutated less often in cancers, is the preceding aspartate (D321N). These mutants were categorized as gain of function in a sensitized melanoma system. In Drosophila developmental assays, we found that the aspartate but not the glutamate mutant caused gain-of-function phenotypes. Here, we catalogued additional properties of these mutants to accrue greater insight into their functions. A modest increase in nuclear retention of E322K was noted. Binding of ERK2 E322K and D321N to a small group of substrates and regulatory proteins was similar, in spite of differences in CD site integrity. Interactions with a second docking site, the F site, which should be more accessible in E322K, were modestly reduced rather than increased. The crystal structure of ERK2 E322K also indicated a disturbed dimer interface, and reduced dimerization was detected by a two-hybrid test; yet, it was detected in dimers in EGF-treated cells, although to a lesser extent than D321N or wt ERK2. These findings indicate a range of small differences in behaviors that may contribute to increased function of E322K in certain cancers.

Silencing circCAMSAP1 suppresses malignant behavior of endometrial cancer by targeting microRNA-370-3p/MAPK1.

The study was conducted to figure out the function and mechanism of circular RNA circCAMSAP1 in repressing malignant behavior of endometrial carcinoma (EC) by targeting microRNA (miR)-370-3p /MAPK1. Tumor tissues and normal adjacent tissues of EC patients were harvested, and circCAMSAP1 and MAPK1 were elevated but miR-370-3p was reduced in tissues and cells of EC patients. Functional test results clarified transfection of si-circCAMSAP1 or miR-370-3p-mimic refrained cancer cell proliferation, migration and invasion, but motivated cancer cell apoptosis. Meanwhile, the amount of E-cadherin elevated and the amount of N-cadherin elevated or reduced. After co-transfection with si-circCAMSAP1 and miR-370-3p-inhibitor, miR-370-3p-inhibitor blocked si-circCAMSAP1's therapeutic impact. Furthermore, after co-transfection of pcDNA-circCAMSAP1 and si-MAPK1, si-MAPK1 turned around the malignant effect of pcDNA-circCAMSAP1. It was testified that miR-370-3p was circCAMSAP1's target, and inversely controlled via circCAMSAP1. Meanwhile, enhancing miR-370-3p led to repressive MAPK1, which was recognized as miR-370-3p's downstream target. All in all, the results of this study convey silencing circCAMSAP1 refrains the malignant behavior of EC by controlling miR-370-3p /MAPK1 axis.

Upregulation of the EGFR/MEK1/MAPK1/2 signaling axis as a mechanism of resistance to antiestrogen­induced BimEL dependent apoptosis in ER+ breast cancer cells.

The epidermal growth factor receptor (EGFR) is commonly upregulated in multiple cancer types, including breast cancer. In the present study, evidence is provided in support of the premise that upregulation of the EGFR/MEK1/MAPK1/2 signaling axis during antiestrogen treatment facilitates the escape of breast cancer cells from BimEL­dependent apoptosis, conferring resistance to therapy. This conclusion is based on the findings that ectopic BimEL cDNA overexpression and confocal imaging studies confirm the pro­apoptotic role of BimEL in ERα expressing breast cancer cells and that upregulated EGFR/MEK1/MAPK1/2 signaling blocks BimEL pro­apoptotic action in an antiestrogen­resistant breast cancer cell model. In addition, the present study identified a pro­survival role for autophagy in antiestrogen resistance while EGFR inhibitor studies demonstrated that a significant percentage of antiestrogen­resistant breast cancer cells survive EGFR targeting by pro­survival autophagy. These pre­clinical studies establish the possibility that targeting both the MEK1/MAPK1/2 signaling axis and pro­survival autophagy may be required to eradicate breast cancer cell survival and prevent the development of antiestrogen resistance following hormone treatments. The present study uniquely identified EGFR upregulation as one of the mechanisms breast cancer cells utilize to evade the cytotoxic effects of antiestrogens mediated through BimEL­dependent apoptosis.

Tumor-suppressive miR-29c binds to MAPK1 inhibiting the ERK/MAPK pathway in pancreatic cancer.

INTRODUCTION: GEO- and TCGA-based data analysis suggested the differential expression of miR-29c in pancreatic cancer. However, limited data are available on the downstream mechanistic actions of miR-29c, which may fuel the in vitro and in vivo studies of pancreatic cancer. METHODS: The downstream target gene of miR-29c and the downstream ERK/MAPK pathway involved in pancreatic cancer were predicted by bioinformatics tools. Next, the expression of miR-29c and MAPK1 was determined in pancreatic cancer tissues and cells. After ectopic expression and depletion experiments in pancreatic cancer cells, oncogenic phenotypes of pancreatic cancer cells were tested by MTS assay, Transwell assay, and flow cytometry. Effects of miR-29c/MAPK1 on tumorigenic ability in vivo were evaluated in pancreatic cancer xenografts in nude mice. RESULTS: Through differential analysis, five pancreatic cancer-related miRNAs (hsa-miR-29c, hsa-miR-107, hsa-miR-324-3p, hsa-miR-375, and hsa-miR-210) were screened out, among which miR-29c was selected as the key miRNA related to prognosis of pancreatic cancer patients. miR-29c could target and inhibit MAPK1 to suppress the activation of ERK/MAPK pathway. miR-29c was downregulated in pancreatic cancer, and its high expression was related to the good prognosis of pancreatic cancer patients. Both in vitro and in vivo experiments demonstrated that restoration of miR-29c inhibited oncogenic phenotypes of pancreatic cancer cells, as well as repressed tumorigenic ability of pancreatic cancer cells in nude mice. CONCLUSIONS: Taken together, we unveil a novel miR-29c/MAPK1/ERK/MAPK axis that suppresses pancreatic cancer both in vitro and in vivo.

LINC01296 promotes proliferation of cutaneous malignant melanoma by regulating miR-324-3p/MAPK1 axis.

OBJECTIVE: To investigate the functions and potential molecular mechanism of LINC01296 regarding the progression of cutaneous malignant melanoma (CMM) by the regulation of miR-324-3p/MAPK1 axis. METHODS: The candidate differential lncRNAs of CMM were selected from GEPIA database, and quantitative real-time PCR (qRT-PCR) was utilized to assess the expression level of LINC01296 in human CMM tissues and cell lines. Cell proliferation assay, Colony formation assay, Ethynyl-2'-deoxyuridine (EDU) assay in vitro and tumorigenicity assays in nude mice in vivo were performed to examine the functions of LINC01296. Bioinformatics analysis, luciferase reporter assay and rescue experiments were also gained an insight into the underlying mechanisms of LINC01296 in CMM cell lines by miR-324-3p/MAPK1 axis. RESULTS: In this study, the up-regulation of LINC01296 was found in CMM tissues and cell lines. Functionally, the over-expression of LINC01296 promoted the proliferation in CMM cell lines. In addition, immunochemistry analysis confirmed that the levels of MAPK1 and Ki-67 in sh-LINC01296-xenografted tumors was weaker than that in sh-NC-xenografted tumors. Then, bioinformatics analysis confirmed that LINC01296 interacted with miR-324-3p. Further investigations showed that MAPK1, which collected from the potential related genes of LINC01296, was the conjugated mRNA of miR-324-3p by luciferase reporter assay. Finally, the rescue experiments suggested the positive regulatory association among LINC01296 and MAPK1, which showed that MAPK1 could reverse the promoting-effect of LINC01296 in CMM cells in vitro. CONCLUSIONS: Therefore, our findings provided insight into the mechanisms of LINC01296 via miR-324-3p/MAPK1 axis in CMM, and revealed an alternative target for the diagnosis and treatment of CMM.

Circular RNA hsa_circ_0023404 promotes the proliferation, migration and invasion in endometrial cancer cells through regulating miR-217/MAPK1 axis.

BACKGROUND: Emerging studies indicated that circular RNA hsa_circ_ 0023404 and its target miR-217/MARK1 axis play a critical role in cancer progression such as non-small cell lung cancer and cervical cancer. However, the role of hsa_circ_0023404/miR-217/MARK1 involved in endometrial cancer (EC) was not investigated yet. The aim of this study is to investigate the functions of hsa_circ_0023404 in endometrial cancer (EC) and the potential molecular mechanism. METHODS: We used RT-qPCR and Western blot approach to detect the expressed levels of related genes in EC cell lines. Transfected siRNAs were applied to knockdown the level of related mRNA in cells. Cell proliferation by CCK-8 assay and colony formation assay were applied to detect cell proliferation. Transwell migration and invasion assay was for detecting the migration and invasion of the cells. RESULTS: RT-qPCR showed that the levels of hsa_circ_0023404 and MARK1 mRNA were upregulated, but mirR-217 was decreased in three endometrial cancer cell lines. Knockdown of hsa_circ_0023404 by siRNA markedly increased the level of miR-217 and reduced the proliferation of the Ishikawa cells. It also inhibited the cell migration and invasion. Anti-miR-217 can reverse the promoted proliferation, migrations and invasion of Ishikawa cells mediated by si-circ_0023404. si-MARK1 restored the inhibited cell proliferation, migration and invasion of the co-transfected Ishikawa cells with si- circ_0023404 and anti-miR-217. CONCLUSION: hsa_circ_0023404 exerts a tumor-promoting role in endometrial cancer by regulating miR-217/MARK1 axis. hsa_circ_0023404 inhibit miR-217 as sponge which inhibit endometrial cancer cell growth and metastasis. MARK1 is downstream target of miR217 and upregulated by hsa_circ_ 0023404/miR-217 axis and involved in the endometrial cancer progression.

MiR-585-5p impedes gastric cancer proliferation and metastasis by orchestrating the interactions among CREB1, MAPK1 and MITF.

Background: Gastric cancer (GC) is one of the most malignant and lethal cancers worldwide. Multiple microRNAs (miRNAs) have been identified as key regulators in the progression of GC. However, the underlying pathogenesis that miRNAs govern GC malignancy remains uncertain. Here, we identified a novel miR-585-5p as a key regulator in GC development. Methods: The expression of miR-585-5p in the context of GC tissue was detected by in situ hybridization for GC tissue microarray and assessed by H-scoring. The gain- and loss-of-function analyses comprised of Cell Counting Kit-8 assay and Transwell invasion and migration assay. The expression of downstream microphthalmia-associated transcription factor (MITF), cyclic AMP-responsive element-binding protein 1 (CREB1) and mitogen-activated protein kinase 1 (MAPK1) were examined by Immunohistochemistry, quantitative real-time PCR and western blot. The direct regulation between miR-585-5p and MITF/CREB1/MAPK1 were predicted by bioinformatic analysis and screened by luciferase reporter assay. The direct transcriptional activation of CREB1 on MITF was verified by luciferase reporter assay, chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assays (EMSAs). The interaction between MAPK1 and MITF was confirmed by co-immunoprecipitation (Co-IP) and immunofluorescent double-labelled staining. Results: MiR-585-5p is progressively downregulated in GC tissues and low miR-585-5p levels were strongly associated with poor clinical outcomes. Further gain- and loss-of-function analyses showed that miR-585-5p possesses strong anti-proliferative and anti-metastatic capacities in GC. Follow-up studies indicated that miR-585-5p targets the downstream molecules CREB1 and MAPK1 to regulate the transcriptional and post-translational regulation of MITF, respectively, thus controlling its expression and cancer-promoting activity. MiR-585-5p directly and negatively regulates MITF together with CREB1 and MAPK1. According to bioinformatic analysis, promotor reporter gene assays, ChIP and EMSAs, CREB1 binds to the promotor region to enhance transcriptional expression of MITF. Co-IP and immunofluorescent double-labelled staining confirmed interaction between MAPK1 and MITF. Protein immunoprecipitation revealed that MAPK1 enhances MITF activity via phosphorylation (Ser73). MiR-585-5p can not only inhibit MITF expression directly, but also hinder MITF expression and pro-cancerous activity in a CREB1-/MAPK1-dependent manner indirectly. Conclusions: In conclusion, this study uncovered miR-585-5p impedes gastric cancer proliferation and metastasis by orchestrating the interactions among CREB1, MAPK1 and MITF.

LINC00511 promotes cervical cancer progression by regulating the miR-497-5p/MAPK1 axis.

BACKGROUND: Long non-coding RNA (lncRNA) exhibits a crucial role in multiple human malignancies. The expression of lncRNA LINC00511, reportedly, is aberrantly up-regulated in several types of tumors. Our research was aimed at deciphering the role and mechanism of LINC00511 in the progression of cervical cancer (CC). METHOD: Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to quantify the expression levels of LINC00511, miR-497-5p and MAPK1 mRNA in CC tissues and cell lines. Cell counting kit-8 (CCK-8), 5-bromo-2'-deoxyuridine (BrdU) and Transwell assays were conducted for detecting the proliferation, migration and invasion of CC cells. Dual-luciferase reporter gene experiments were performed to verify the targeting relationships amongst LINC00511, miR-497-5p and MAPK1. Besides, MAPK1 expression in CC cells was detected via Western blot after LINC00511 and miR-497-5p were selectively regulated. RESULTS: Up-regulation of LINC00511 expression in CC tissues and cell lines was observed, which was in association with tumor size, clinical stage and lymph node metastasis of the patients. LINC00511 overexpression facilitated the proliferation, migration and invasion of CC cells, while opposite effects were observed after knockdown of LINC00511. Mechanistically, LINC00511 was capable of targeting miR-497-5p and up-regulating MAPK1 expression. CONCLUSION: LINC00511/miR-497-5p/MAPK1 axis regulates CC progression.

The role of ERK-1 and ERK-2 gene polymorphisms in PCOS pathogenesis.

BACKGROUND: Ovulation is regulated by extracellular signal-regulated kinase-1 (ERK-1) and ERK-2 signaling mechanisms, and ERK-1/2 kinases modulates the function of most of the LH-regulated genes. Defective ERK kinase signaling that is secondary to a genetic problem contributes to both ovulatory dysfunction and metabolic problems in polycystic ovary syndrome (PCOS). We planned to investigate ERK-1 and ERK-2 gene polymorphisms in PCOS for the first time in the Turkish population. METHODS: One hundred two PCOS patients and 102 healthy controls were recruited for this patient control study. HOMA-IR, Ferriman-Gallwey score (FGS), waist-to-hip ratio (WHR), and body mass index (BMI) were assessed. Lipid profile levels, CRP, and total testosterone were determined. ERK-2 rs2276008 (G > C) and ERK-1 rs11865228 (G > A) SNPs were analyzed with a real-time PCR system. RESULTS: ERK-1 and ERK-2 genotypes were found to differ between the PCOS and control groups. In patients with PCOS, ERK-1 GA and ERK-2 GC genotypes were different in terms of BMI, FGS, HOMA-IR, CRP, total testosterone, and total cholesterol levels. CONCLUSIONS: ERK-1 and ERK-2 genes are involved in PCOS pathogenesis. BMI, FGS, HOMA-IR, and CRP levels are related to the heterozygote polymorphic types of ERK-1 and ERK-2 genes.

Suppression of MIR31HG affects the functional properties of thyroid cancer cells depending on the miR-761/MAPK1 axis.

BACKGROUND: Thyroid cancer is the most prevalent endocrine malignancy. Long non-coding RNA (lncRNA) MIR31HG is abnormally expressed in thyroid cancer tissues. However, the precise, critical role of MIR31HG in thyroid cancer development remains unclear. METHODS: MIR31HG, microRNA (miR)-761 and mitogen-activated protein kinase 1 (MAPK1) were quantified by quantitative real-time PCR (qRT-PCR) and immunoblotting. Cell viability, proliferation, apoptosis, invasion and migration abilities were evaluated by MTS, 5-Ethynyl-2'-Deoxyuridine (EdU), flow cytometry, transwell and wound-healing assays, respectively. Dual-luciferase reporter assays were used to validate the direct relationship between miR-761 and MIR31HG or MAPK1. RESULTS: MIR31HG was overexpressed in human thyroid cancer, and its overexpression predicted poor prognosis. Suppression of MIR31HG impeded cell proliferation, invasion and migration, as well as promoted cell apoptosis in vitro, and diminished the growth of xenograft tumors in vivo. Mechanistically, MIR31HG targeted and regulated miR-761. Moreover, miR-761 was identified as a molecular mediator of MIR30HG function in regulating thyroid cancer cell behaviors. MAPK1 was established as a direct and functional target of miR-761 and MAPK1 knockdown phenocopied miR-761 overexpression in impacting thyroid cancer cell behaviors. Furthermore, MIR31HG modulated MAPK1 expression by competitively binding to miR-761 via the shared binding sequence. CONCLUSION: Our findings demonstrate that MIR31HG targets miR-761 to regulate the functional behaviors of thyroid cancer cells by upregulating MAPK1, highlighting a strong rationale for developing MIR31HG as a novel therapeutic target against thyroid cancer.

ERK1/2 Activity Is Critical for the Outcome of Ischemic Stroke.

Ischemic disorders are the leading cause of death worldwide. The extracellular signal-regulated kinases 1 and 2 (ERK1/2) are thought to affect the outcome of ischemic stroke. However, it is under debate whether activation or inhibition of ERK1/2 is beneficial. In this study, we report that the ubiquitous overexpression of wild-type ERK2 in mice (ERK2wt) is detrimental after transient occlusion of the middle cerebral artery (tMCAO), as it led to a massive increase in infarct volume and neurological deficits by increasing blood-brain barrier (BBB) leakiness, inflammation, and the number of apoptotic neurons. To compare ERK1/2 activation and inhibition side-by-side, we also used mice with ubiquitous overexpression of the Raf-kinase inhibitor protein (RKIPwt) and its phosphorylation-deficient mutant RKIPS153A, known inhibitors of the ERK1/2 signaling cascade. RKIPwt and RKIPS153A attenuated ischemia-induced damages, in particular via anti-inflammatory signaling. Taken together, our data suggest that stimulation of the Raf/MEK/ERK1/2-cascade is severely detrimental and its inhibition is rather protective. Thus, a tight control of the ERK1/2 signaling is essential for the outcome in response to ischemic stroke.

Long non-coding RNA terminal differentiation-induced non-coding RNA regulates cisplatin resistance of choroidal melanoma by positively modulating extracellular signal-regulated kinase 2 via sponging microRNA-19b-3p.

In the present study, we aimed to investigate the role of long non-coding RNA terminal differentiation-induced non-coding RNA (TINCR) in cisplatin (DDP) resistance of choroidal melanoma (CM) and the potential molecular mechanisms. CM and non-CM tissues were collected from 60 CM patients. DDP-resistant CM cells were obtained by selection with linearly increased DDP treatment. The expression levels of TINCR, microR-19b-3p (miR-19b-3p), and extracellular signal-regulated kinase 2 (ERK-2) were detected by quantitative real-time PCR. Cholecystokinin octapeptide (CCK-8) assay was utilized to detect chemosensitivity and cell viability. Flow cytometry analysis was performed to detect apoptotic cells. The protein levels of Bax, Bcl-2, cleaved-caspase-3, ERK-2, and nuclear factor-kappa B p65 were measured by Western blot. RNA immunoprecipitation (RIP) and dual-luciferase reporter assays were performed to determine the relationship among TINCR, miR-19b-3p, and ERK-2. The results showed that the levels of TINCR and ERK-2 were markedly increased in DDP-resistant CM tissues and cells, while miR-19b-3p level was significantly reduced. TINCR knockdown reduced DDP resistance and cell viability and promoted cell apoptosis, while TINCR overexpression exhibited opposite effects. TINCR and ERK-2 were direct targets of miR-19b-3p. Further experiments revealed that TINCR enhanced DDP resistance in CM cells by regulating the miR-19b-3p/ERK-2/NF-kb axis. Taken together, our study revealed a critical role of TINCR in regulating DDP resistance in CM and suggested that TINCR is a potential cisplatin-resistant CM therapeutic target.