Mitogen-activated protein kinases: specific messages from ubiquitous messengers

New emerging roles of CD133 in cancer stem cell: Signaling pathway and miRNA regulation

Cancer stem cells (CSC) are rare immortal cells within a tumor that are able to initiate tumor progression, development, and resistance. Advances studies show that, like normal stem cells, CSCs can be both self-renewed and given rise to many cell types, therefore form tumors. A number of cell surface markers, such as CD44, CD24, and CD133 are frequently used to identify CSCs. CD133, a transmembrane glycoprotein, either alone or in collaboration with other markers, has been mainly considered to identify CSCs from different solid tumors. However, the exactness of CD133 as a cancer stem cell biomarker has not been approved yet. The clinical importance of CD133 is as a CSC marker in many cancers. Also, it contributes to shorter survival, tumor progression, and tumor recurrence. The expression of CD133 is controlled by many extracellular or intracellular factors, such as tumor microenvironment, epigenetic factors, signaling pathways, and miRNAs. In this study, it was attempted to determine: 1) CD133 function; 2) the role of CD133 in cancer; 3) CD133 regulation; 4) the therapeutic role of CD133 in cancers.

Oncogenic Signaling in Tumorigenesis and Applications of siRNA Nanotherapeutics in Breast Cancer

Overexpression of oncogenes and cross-talks of the oncoproteins-regulated signaling cascades with other intracellular pathways in breast cancer could lead to massive abnormal signaling with the consequence of tumorigenesis. The ability to identify the genes having vital roles in cancer development would give a promising therapeutics strategy in combating the disease. Genetic manipulations through siRNAs targeting the complementary sequence of the oncogenic mRNA in breast cancer is one of the promising approaches that can be harnessed to develop more efficient treatments for breast cancer. In this review, we highlighted the effects of major signaling pathways stimulated by oncogene products on breast tumorigenesis and discussed the potential therapeutic strategies for targeted delivery of siRNAs with nanoparticles in suppressing the stimulated signaling pathways.

Downregulation of Protein Tyrosine Phosphatase Receptor Type R Accounts for the Progression of Hirschsprung Disease

Hirschsprung disease (HSCR) is a common developmental disorder of the enteric nervous system (ENS). However, the disease mechanisms have not been fully elucidated. To better understand the etiology of HSCR, the role and mechanism of HSCR associated PTPRR (protein tyrosine phosphatase receptor-type R) in the multipotency of ENS progenitors and ENS development were explored. In the present study, the downregulated PTPRR expression in HSCR was reflected by microarray and validated by real-time PCR analyses. Moreover, PTPRR protein was mainly expressed in the cytoplasmic area of primary cultured ENS progenitors (Enteric neural crest cells, ENCCs) and significantly decreased after differentiation induction, which implies the anti-differentiation role in ENCCs. Further study employed an adenovirus transfection system. After genetic modulation, the ENCCs maintained undifferentiated patterns even in GDNF (Glial cell-line derived neurotrophic factor)-mediated directional differentiation, as well as significantly increased EdU positive immunofluorescence in the PTPRR overexpressing group while the development of the ENS was stunted in the PTPRR knockdown fetal gut. Moreover, the expression of ERK1/2 activated by GDNF was significantly decreased as reflected by western-blot or immunofluorescence analyses after genetic modulation in the PTPRR overexpressing group, which suggests the potential mechanism in regulating the MAPK/ERK1/2 pathway. Taken together, These data support the idea that PTPRR may ensure a certain number of neural precursor cells by inhibiting ENCC overt differentiation and maintaining ENCC proliferation, which is considered to be the multipotency of ENCCs, and eventually participate in the development of the ENS, and establish PTPRR protein as negative regulator of MAPK/ERK1/2 signaling cascades in neuronal differentiation and demonstrate their involvement in the pathophysiology of HSCR.

Identifiability from a Few Species for a Class of Biochemical Reaction Networks

Under mass-action kinetics, biochemical reaction networks give rise to polynomial autonomous dynamical systems whose parameters are often difficult to estimate. We deal in this paper with the problem of identifying the kinetic parameters of a class of biochemical networks which are abundant, such as multisite phosphorylation systems and phosphorylation cascades (for example, MAPK cascades). For any system of this class, we explicitly exhibit a single species for each connected component of the associated digraph such that the successive total derivatives of its concentration allow us to identify all the parameters occurring in the component. The number of derivatives needed is bounded essentially by the length of the corresponding connected component of the digraph. Moreover, in the particular case of the cascades, we show that the parameters can be identified from a bounded number of successive derivatives of the last product of the last layer. This theoretical result induces also a heuristic interpolation-based identifiability procedure to recover the values of the rate constants from exact measurements.

Geniposide ameliorated fluoxetine-suppressed neurite outgrowth in Neuro2a neuroblastoma cells

AIM

Fluoxetine (FXT), a selective serotonin reuptake inhibitor (SSRI), is one of the most common psychiatric medications clinically prescribed; while over-produced serotonin may suppress neurite development. The role of major iridoids like geniposide (GPS) and genipin (GNP) from Gardenia jasminoides Ellis fruit (family Rubiaceae) in ameliorating the anti-neurite outgrowth effect of FXT is poorly understood. In this study, the effects of these iridoids on FXT-suppressed neurite outgrowth in Neuro2a neuroblastoma cells were investigated.

MAIN METHODS

Neuro2a cells were treated with FXT and GPS. The effect of GPS-FXT co-treatment on neurite outgrowth was observed using inverted phase-contrast microscope imaging system, while neurite outgrowth markers - microtubule-associated protein-2 (MAP2) and growth-associated protein 43 (GAP43) were analyzed using RT-PCR, Western blot and immunofluorescence staining. The transcription factor-cAMP response element binding (CREB), and signaling pathways - mitogen-activated protein kinase (MAPK) and protein kinase B/mammalian target of rapamycin (AKT/mTOR) were also analyzed with the help of Western blot.

KEY FINDINGS

The results showed that FXT decreased the neurite outgrowth in Neuro2a cells and also downregulated gene and protein expression of MAP2 and GAP43. It also downregulated the protein expression of phosphorylated-CREB, MAPK, and AKT/mTOR signaling pathways. In contrast, GPS counteracted the effects of FXT. GPS-FXT co-treatment increased the percentage of neurite-bearing cells by 3.6-fold at 200 μM as compared to FXT treatment only.

SIGNIFICANCE

This study has provided the possible molecular mechanism showing how FXT exerted its detrimental side-effects on the neurite differentiation, and via the same mechanism how GPS attenuated these side effects.

Two novel MKKs (MKK4 and MKK7) from Ctenopharyngodon idella are involved in the intestinal immune response to bacterial muramyl dipeptide challenge

Mitogen-activated protein kinase kinases (MKKs) are a class of evolutionarily conserved signalling intermediates of the MAPK signalling pathway that can be activated by a diverse range of pathogenic stimuli and are crucial for the regulation of host immune defence. In this study, two fish MKK genes (CiMKK4 and CiMKK7) were first identified and characterized from grass carp (Ctenopharyngodon idella). Similar to other reported MKKs, the present CiMKK4 and CiMKK7 contained a conserved serine/threonine protein kinase (S_TKc) domain and a canonical dual phosphorylation motif. Quantitative real-time PCR results showed that CiMKK4 and CiMKK7 were broadly transcribed in all selected tissues and developmental stages of grass carp. The mRNA expression levels of CiMKK4 and CiMKK7 in the intestine were significantly induced by bacterial muramyl dipeptide (MDP) challenge in a time-dependent manner (P < 0.01). Additionally, the stimulatory effects of bacterial MDP on CiMKK4 and CiMKK7 expression in the intestine were inhibited by the bioactive dipeptide β-alanyl-l-histidine (carnosine) and alanyl-glutamine (Ala-Gln) (P < 0.05). Moreover, overexpression analysis revealed that CiMKK4 and CiMKK7 were localized throughout the entire cell and could significantly enhance AP-1 reporter gene activation in HEK293T cells. Taken together, these results provide the first experimental demonstration that CiMKK4 and CiMKK7 are involved in the intestinal immune response to MDP challenge in C. idella, which may provide new insight into the bacterial-induced intestinal inflammation of bony fishes.

Apoptotic effect of enterodiol, the final metabolite of edible lignans, in colorectal cancer cells

BACKGROUND

Enterodiol (END) is transformed by human intestinal bacteria from lignans contained in various whole-grain cereals, nuts, legumes, flaxseed, and vegetables. It is known to have several physiological effects, but its effects on mitogen-activated protein kinase (MAPK) signaling and apoptosis in colorectal cancer (CRC) cells have not yet been elucidated. We therefore investigated the effects of END on apoptosis in CRC cells and whether these effects are mediated via MAPK signaling.

RESULTS

Cell proliferation was decreased by END treatment in a time-dependent manner. In particular, END treatment resulted in an apoptosis rate of up to 40% in CT26 cells but showed no cytotoxicity toward RAW264.7 macrophages. Treatment with END also suppressed the migration of CRC cells in a concentration-dependent manner. The phosphorylation of extracellular signal-regulated kinase (ERK), jun N-terminal kinase (JNK), and p38 was down-regulated with END treatment. Furthermore, END decreased the expression levels of anti-apoptotic proteins in CRC cells.

CONCLUSION

Enterodiol inhibited the growth of CRC cells by controlling the MAPK signaling pathway involved in proliferation and apoptosis. These results demonstrate that END has an apoptotic effect in CRC cells. © 2018 Society of Chemical Industry.

Design, synthesis and biological evaluation of cobalt(II)-Schiff base complexes as ATP-noncompetitive MEK1 inhibitors

In this report, we designed and synthesized a series of cobalt(II)-Schiff base complexes (CoSBC) with competent MEK1 (mitogen-activated protein kinase kinase-1) inhibitory activity. Based on our previous report, the CoSBC exhibited high binding affinity with MEK1 protein. To further explore metal complexes as MEK1 inhibitors, a series of transition metals and ligands were employed to build a library of various metal Schiff base complexes. The MEK inhibition assays revealed that only CoSBC exhibited obvious inhibitory activity, complex 2b showed the best inhibition both in BRaf (B-rapidly accelerated fibrosarcoma)/MEK1 and MEK1/ERK2 (extracellular signal-regulated kinases-2) cascading (IC₅₀ is 1.988 ± 0.14 μM and 1.589 ± 0.054 μM respectively). In addition, homogeneous time-resolved fluorescence test method was used to prove that CoSBC as ATP-noncompetitive MEK1 inhibitor. MEK kinase selectivity assay indicated that CoSBC can selectively inhibit MEK1/2 kinases rather than other MAPKs (mitogen-activated protein kinases) family kinases. Moreover, the interaction mode of 2b with MEK1 protein has been demonstrated by computer aided drug design.

β-Apopicropodophyllin functions as a radiosensitizer targeting ER stress in non-small cell lung cancer

AIMS

In this study, we examined whether β-apopicropodophyllin (APP) could act as a radiosensitizer in non-small cell lung cancer (NSCLC) cells.

MAIN METHODS

The in vitro radiosensitizing activity of APP was demonstrated with clonogenic assay, immunoblotting, Annexin V-Propidium iodide (PI) assay, BrdU incorporation, detection of mitochondrial ROS/intracellular of H₂O₂, mitochondrial membrane potential detection, and performing of isolation of mitochondrial and cytosolic fractions. The in vivo radiosensitizing activity of APP was determined in xenografted mice with co-treatment of APP and IR based on measurement of tumor volumes and apoptotic cell death.

KEY FINDINGS

The results of a clonogenic assay indicated that a combination of APP and γ-ionizing radiation (IR) inhibits cell growth and increases cell death in NSCLC cells. Several signal transduction pathways were examined for their potential involvement in the apparent radiosensitization effect of APP, as assessed by immunoblotting analyses and mitochondrial potential determination in vitro. Treatment of NCI-H460 cells with 15 nM APP and NCI-H1299 cells with 10 nM APP yielded dose-enhancement ratios of 1.44 and 1.24, respectively. Enhanced ER stress, disrupted mitochondrial membrane potential, and increased reactive oxygen species (ROS) were observed in cells co-treated with APP and IR, and this was followed by the cytosolic release of cytochrome c and consequent activation of caspase-3 and -9. Notably, inhibition of JNK, which prevents caspase activation, blocked the APP/IR-induced activations of ER stress and apoptotic cell death. In NCI-H460 or NCI-H1299 cell-xenografted mice, APP/IR treatment delayed the time it took tumors to reach a threshold size by 22.38 and 16.83 days, respectively, compared with controls, to yield enhancement factors of 1.53 and 1.38, respectively.

SIGNIFICANCE

APP has a radiosensitizing function derived from its ability to induce apoptotic cell death via activation of ER stress, disruption of mitochondrial membrane potential, and induction of the caspase pathway.

STK33/ERK2 signal pathway contribute the tumorigenesis of colorectal cancer HCT15 cells

Serine/threonine kinase 33 (STK33) is a serine/threonine kinase and participates in many apoptotic process. Herein, we found that the extracellular signal-regulated kinase 2 (ERK2) was a substrate of STK33. STK33 phosphorylated ERK2 and increased the activity of ERK2 and promote the tumorigenesis of colorectal cancer HCT15 cells. Clinical simple showed that STK33 was highly expression in colorectal cells and tissues. Ex vivo and in vivo studies demonstrated that STK33 accelerate tumorigenic properties in NCM460 cells and athymic nude rats. In vitro kinase assay results indicated that STK33 can phosphorylate ERK2. Ex vivo studies further showed that STK33 can bind with ERK2 and take part in the regulation of ERKs signaling pathway. In short, our results showed that STK33 is a novel upstream kinase of ERK2. It may provide a better prospect for STK33 based prevention and treatment for colorectal cancer patients.

Anti-inflammatory Effects of Gossypol on Human Lymphocytic Jurkat Cells via Regulation of MAPK Signaling and Cell Cycle

Gossypol, a natural polyphenolic compound extracted from cottonseed oil, has been reported to possess pharmacological properties via modulation cell cycle and immune signaling pathway. However, whether gossypol has anti-inflammatory effects against phytohemagglutinin (PHA)-induced cytokine secretion in T lymphocytes through similar mechanism remains unclear. Using the T lymphocytes Jurkat cell line, we found that PHA exposure caused dramatic increase in interleukin-2 (IL-2) mRNA expression as well as IL-2 secretion. All of these PHA-stimulated reactions were attenuated in a dose-dependent manner by being pretreated with gossypol. However, gossypol did not show any in vitro cytotoxic effect at doses of 5-20 μM. As a possible mechanism underlying gossypol action, such as pronounced suppression IL-2 release, robust decreased PHA-induced phosphorylation of p38 and c-Jun N-terminal kinase expressions was found with gossypol pretreatment, but not significant phosphorylation of extracellular signal-regulated kinase expression. Furthermore, gossypol could suppress the Jurkat cells' growth, which was associated with increased percentage of G1/S phase and decreased fraction of G2 phase in flow cytometry test. We conclude that gossypol exerts anti-inflammatory effects probably through partial attenuation of mitogen-activated protein kinase (phosphorylated JNK and p38) signaling and cell cycle arrest in Jurkat cells.

Targeting ERK1/2 protein-serine/threonine kinases in human cancers

ERK1 and ERK2 are key protein kinases that contribute to the Ras-Raf-MEK-ERK MAP kinase signalling module. This pathway participates in the control of numerous processes including apoptosis, cell proliferation, the immune response, nervous system function, and RNA synthesis and processing. MEK1/2 activate human ERK1/2 by first catalyzing the phosphorylation of Y204/187 and then T202/185, both residues of which occur within the activation segment. The phosphorylation of both residues is required for enzyme activation. The only Raf substrates are MEK1/2 and the only MEK1/2 substrates are ERK1/2. In contrast, ERK1/2 catalyze the phosphorylation of many cytoplasmic and nuclear substrates including transcription factors and regulatory molecules. The linear MAP kinase pathway branches extensively at the ERK1/2 node. ERK1/2 are proline-directed kinases that preferentially catalyze the phosphorylation of substrates containing a PxS/TP sequence. The dephosphorylation and inactivation of ERK1/2 is catalyzed by dual specificity phosphatases, protein-tyrosine specific phosphatases, and protein-serine/threonine phosphatases. The combined functions of kinases and phosphatases make the overall process reversible. To provide an idea of the complexities involved in these reactions, somatic cell cycle progression involves the strict timing of more than 32,000 phosphorylation and dephosphorylation events as determined by mass spectrometry. The MAP kinase cascade is perhaps the most important oncogenic driver of human cancers and the blockade of this signalling module by targeted inhibitors is an important anti-tumor strategy. Although numerous cancers are driven by MAP kinase pathway activation, thus far the only orally effective approved drugs that target this signaling module are used for the treatment of BRAF-mutant melanomas. The best treatments include the combination of B-Raf and MEK inhibitors (dabrafenib and trametinib, encorafenib and binimetinib, vemurafenib and cobimetanib). However, resistance to these antagonists occurs within one year and additional treatment options are necessary. Owing to the large variety of malignancies that are driven by dysregulation of the MAP kinase pathway, additional tumor types should be amenable to MAP kinase pathway inhibitor therapy. In addition to new B-Raf and MEK inhibitors, the addition of ERK inhibitors should prove helpful. Ulixertinib, MK-8353, and GDC-0994 are orally effective, potent, and specific inhibitors of ERK1/2 that are in early clinical trials for the treatment of various advanced/metastatic solid tumors. These agents are effective against cell lines that are resistant to B-Raf and MEK1/2 inhibitor therapy. Although MK-8353 does not directly inhibit MEK1/2, it decreases the phosphorylation of ERK1/2 as well as the phosphorylation of RSK, an ERK1/2 substrate. The decrease in RSK phosphorylation appears to be a result of ERK inhibition and the decrease in ERK1/2 phosphorylation is related to the inability of MEK to catalyze the phosphorylation of the ERK-MK-8353 complex; these decreases characterize the ERK dual mechanism inhibition paradigm. Additional work will be required to determine whether ERK inhibitors will be successful in the clinic and are able to forestall the development of drug resistance of the MAP kinase pathway.

Network Pharmacology and Reverse Molecular Docking-Based Prediction of the Molecular Targets and Pathways for Avicularin Against Cancer

AIM AND OBJECTIVE

Avicularin has been found to inhibit the proliferation of HepG-2 cells in vitro in the screening of our laboratory. We intended to explain the molecular mechanism of this effect. Therefore, the combined methods of reverse molecular docking and network pharmacology were used in order to illuminate the molecular mechanisms for Avicularin against cancer.

MATERIALS AND METHODS

Potential targets associated with anti-tumor effects of Avicularin were screened by reverse molecular docking, then a protein database was established through constructing the drugprotein network from literature mining data, and the protein-protein network was built through an in-depth exploration of the relationships between the proteins, and then the network topology analysis was performed. Additionally, gene function and signaling pathways were analyzed by Go bio-enrichment and KEGG Pathway.

RESULTS

The result showed that Avicularin was closely related to 16 targets associated with cancer, and it may significantly influence the pro-survival signals in MAPK signaling pathway that can activate and regulate a series of cellular activities and participate in the regulation of cell proliferation, differentiation, transformation and apoptosis.

CONCLUSION

The network pharmacology strategy used herein provided a powerful means for the mechanisms of action for bioactive ingredients.

Small Non-Coding RNAs Derived From Eukaryotic Ribosomal RNA

The advent of RNA-sequencing (RNA-Seq) technologies has markedly improved our knowledge and expanded the compendium of small non-coding RNAs, most of which derive from the processing of longer RNA precursors. In this review article, we will present a nonexhaustive list of referenced small non-coding RNAs (ncRNAs) derived from eukaryotic ribosomal RNA (rRNA), called rRNA fragments (rRFs). We will focus on the rRFs that are experimentally verified, and discuss their origin, length, structure, biogenesis, association with known regulatory proteins, and potential role(s) as regulator of gene expression. This relatively new class of ncRNAs remained poorly investigated and underappreciated until recently, due mainly to the a priori exclusion of rRNA sequences-because of their overabundance-from RNA-Seq datasets. The situation surrounding rRFs resembles that of microRNAs (miRNAs), which used to be readily discarded from further analyses, for more than five decades, because no one could believe that RNA of such a short length could bear biological significance. As if we had not yet learned our lesson not to restrain our investigative, scientific mind from challenging widely accepted beliefs or dogmas, and from looking for the hidden treasures in the most unexpected places.

MEK2 Negatively Regulates Lipopolysaccharide-Mediated IL-1β Production through HIF-1α Expression

LPS-activated macrophages require metabolic reprogramming and glucose uptake mediated by hypoxia-inducible factor (HIF)-1 α and glucose transporter 1 (Glut1) expression for proinflammatory cytokine production, especially IL-1β. This process is tightly regulated through activation of MAPK kinases, including the MEK/ERK pathway as well as several transcription factors including HIF-1α. Although MAPK kinase (MEK) 2 deficiency had no significant effect on NO, TNF-α, or IL-12 production in response to LPS challenge, MEK2-deficient murine bone marrow-derived macrophages (BMDMs) exhibited lower IL-10 production. Importantly, MEK2-deficient BMDMs exhibited a preserved ERK1/2 phosphorylation, higher HIF-1α and Glut1 levels, and substantially increased IL-1β as well as IL-6 production in response to LPS stimulation. Knockdown of HIF-1α expression via short interference RNA decreased the level of HIF-1α expression in MEK2-deficient BMDMs and decreased IL-1β production in response to LPS treatment. Furthermore, we performed gain of function experiments by overexpressing MEK2 protein in RAW264.7 cells. LPS stimulation of MEK2 overexpressed in RAW264.7 cells led to a marked decreased IL-1β production. Finally, we investigated the role of Mek1 and Mek2 double and triple mutation on ERK phosphorylation, HIF-1α expression, and IL-1β production. We found that MEK2 is the major kinase, which inversely proportionally regulates HIF-1α and IL-1β expression independent of ERK activation. Our findings demonstrate a novel regulatory function for MEK2 in response to TLR4 activation in IL-1β production through modulating HIF-1α expression.

Cold Physical Plasma Modulates p53 and Mitogen-Activated Protein Kinase Signaling in Keratinocytes

Small reactive oxygen and nitrogen species (ROS/RNS) driven signaling plays a significant role in wound healing processes by controlling cell functionality and wound phase transitions. The application of cold atmospheric pressure plasma (CAP), a partially ionized gas expelling a variety of ROS and RNS, was shown to be effective in chronic wound management and contrastingly also in malignant diseases. The underlying molecular mechanisms are not well understood but redox signaling events are involved. As a central player, the cellular tumor antigen p53 governs regulatory networks controlling proliferation, death, or metabolism, all of which are grossly modulated by anti- and prooxidant signals. Using a human skin cell model, a transient phosphorylation and nuclear translocation of p53, preceded by the phosphorylation of upstream serine- (ATM) and serine/threonine-protein kinase (ATR), was detected after CAP treatment. Results indicate that ATM acts as a direct redox sensor without relevant contribution of phosphorylation of the histone A2X, a marker of DNA damage. Downstream events are the activation of checkpoint kinases Chk1/2 and several mitogen-activated (MAP) kinases. Subsequently, the expression of MAP kinase signaling effectors (e.g., heat shock protein Hsp27), epithelium derived growth factors, and cytokines (Interleukins 6 + 8) was increased. A number of p53 downstream effectors pointed at a decrease of cell growth due to DNA repair processes. In summary, CAP treatment led to an activation of cell repair and defense mechanisms including a modulation of paracrine inflammatory signals emphasizing the role of prooxidant species in CAP-related cell signaling.

Vitronectin, fibronectin and epidermal growth factor induce proliferation via the JNK and ERK pathways in insulinoma INS-1 cells

An insulinoma is a tumor formed by beta cells in the Langerhans islets of the pancreas. Vitronectin (VTN), fibronectin (FN) and epidermal growth factor (EGF) are important in cell signaling. The aim of this study was to investigate the molecular mechanism that occurs in INS-1 cells with the administration of VTN, FN and EGF in proliferative doses. We determined the proliferative doses of EGF, VTN and FN. The molecular mechanism of proliferation has been investigated alone or in the combination of these proteins. It was observed that INS-1 cells did not have VTN and FN. Cell viability increased with the administration of 0.1 μg/ml VTN, 0.1 μg/ml FN and 1 mg/ml EGF. Proliferation increased with the administration of FN + EGF, and VTN + FN + EGF together when compared to the control group. The total JNK levels did not change between the groups; however, the active JNK levels increased in the VT + FN + EGF group compared to the control group. The total ERK levels increased in the VT + FN + EGF group, and the active ERK levels increased in the VTN + FN, VTN + EGF and VTN + FN + EGF groups compared to the control group. The JNK and ERK pathways are important for proliferation. The JNK and ERK pathways were activated in VTN + FN + EGF administered group. However, it was observed that the ERK pathway was more active than the JNK pathway.

Characterization and functional analysis of grouper (Epinephelus coioides) MEK1 and MEK2

MEK dual-specificity protein kinases are a group of mitogen-activated protein kinase kinases, which act as an integration point by transferring extracellular signals to the nucleus. To investigate the function of MEK in teleost fish, we cloned MEK1 and MEK2 cDNA sequences from the orange-spotted grouper (Epinephelus coioides). EcMEK1 and EcMEK2 shared 80% amino acid identity with each other. EcMEK1 had 89-99% amino acid identity with teleosts or mammals, whereas EcMEK2 shared 85-97% amino acid identity. The exon structures of the grouper MEK1/2 genes were conserved with zebrafish and human MEK1/2. Tissue distribution analysis showed that EcMEK1 and EcMEK2 had a similar expression pattern in grouper tissues and was mainly transcribe in systemic immune organs. Both EcMEK1 and EcMEK2 were distributed throughout the cytoplasm of transfected GS or HEK293T cells. Overexpression of EcMEK1 or EcMEK2 activated Activator protein 1 dependent luciferase. The phosphorylation levels of EcMEK1/2 and EcERK1/2 were significantly increased in head kidney leukocytes by stimulation with PMA treatment. The grouper MEK1/2-ERK1/2 axis was activated in Cryptocaryon irritans infection and showed an enhanced phosphorylation after immunization.

Role of AMPK in mammals reproduction: Specific controls and whole-body energy sensing

AMP-activated protein kinase (AMPK) is a key enzyme involved in linking the energy sensing to metabolic pathways. As such, it plays a central role at the whole-body level to translate endocrine communications into adapted responses aimed either at saving energy when food is scarce or at allocating it to various functions, particularly reproduction, when food is available. AMPK also plays major roles in the energy individual cells use in order to realize their specific functions. This is of course especially true for all cells involved in the reproductive function (gonads, gametes) or in its control (hypothalamus, pituitary). In the present review, I report a survey of the various roles of AMPK functions in reproduction, either directly in reproductive organs, or indirectly in organs controlling reproduction, particularly at hypothalamus level.

Method for Studying the Effect of Gene Silencing on Bacterial Infection-induced ERK1/2 Signaling in Bone-marrow Derived Macrophages

Macrophages are highly phagocytic cells that utilize various pathogen recognition receptors (PRRs) to recognize pathogen-associated molecular patterns (PAMPs). These PAMPs can be present within the microbe, such as bacterial CpG DNA, and are recognized by Toll-like receptor 9 (TLR9), a PRR present on the endosomal membrane of macrophages. PAMPs can also be present on the surface of microbes, such as Lipopolysaccharide (LPS), which decorates the outer membrane of gram-negative bacteria like Salmonella typhimurium and Escherichia coli. LPS is recognized by TLR4 present on the plasma membrane of macrophages, and LPS-TLR4 association leads to activation of signaling cascades including MAPK phosphorylation, which in turn promotes macrophage activation and microbial killing. This protocol describes the method for studying the role of a gene of interest in Extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) signaling, induced by bacterial infection in primary bone-marrow derived macrophages (BMDMs).

MiR-145-modulated SOX9-mediated hypospadias through acting on mitogen-activated protein kinase signaling pathway

This study primarily explored how miR-145, mitogen-activated protein kinase (MAPK) signaling and a downstream transcription factor (i.e., SOX9) mediated development of hypospadias. The hypospadias tissues and preputial tissues were isolated from pediatric inpatients postoperatively. Simultaneously, the rat models of hypospadias were established, and spermatogonial stem cells were separated. The expressions of proteins that symbolized cell apoptosis and oxidative stress were quantified via western blot analysis. Furthermore, the apoptosis, proliferation, and viability of cells were evaluated by means of flow cytometry, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and colony formation assays. The results of microarray indicated miR-145 as a differentially expressed biomarker between hypospadias tissues and normal tissues (p < 0.05). Moreover, rat models of hypospadias were observed with markedly lower vitamins A and E levels, reduced expressions of proteins relevant to oxidative stress (i.e., Nrf2, HO-1, Gpx, and SOD-1), as well as enhanced Bax and cleaved caspase-3 expressions ( p < 0.05). Furthermore, SOX9 was found to be targeted by miR-145, and it was also modified by phosphorylated extracellular-regulated kinase (p-ERK), a portion of MAPK signaling ( p < 0.05). The p-ERK was significantly regulated after altering the expression of miR-145 ( p < 0.05). Moreover, activation of p-ERK and transfection of pcDNA-SOX9 could cause higher expression of apoptins and larger apoptotic proportion of cells ( p < 0.05), yet transfection of miR-145 mimic led to improved cell apoptosis and depressed cell viability ( p < 0.05). In conclusion, SOX9, which was regulated by both miR-145 and miR-145/MAPK signaling, could be involved in the pathogenesis of hypospadias.

Recent advances in TMEM16A: Structure, function, and disease

TMEM16A (also known as anoctamin 1, ANO1) is the molecular basis of the calcium-activated chloride channels, with ten transmembrane segments. Recently, atomic structures of the transmembrane domains of mouse TMEM16A (mTMEM16A) were determined by single-particle electron cryomicroscopy. This gives us a solid ground to discuss the electrophysiological properties and functions of TMEM16A. TMEM16A is reported to be dually regulated by Ca²⁺ and voltage. In addition, the dysfunction of TMEM16A has been found to be involved in many diseases including cystic fibrosis, various cancers, hypertension, and gastrointestinal motility disorders. TMEM16A is overexpressed in many cancers, including gastrointestinal stromal tumors, gastric cancer, head and neck squamous cell carcinoma (HNSCC), colon cancer, pancreatic ductal adenocarcinoma, and esophageal cancer. Furthermore, overexpression of TMEM16A is related to the occurrence, proliferation, and migration of tumor cells. To date, several studies have shown that many natural compounds and synthetic compounds have regulatory effects on TMEM16A. These small molecule compounds might be novel drugs for the treatment of diseases caused by TMEM16A dysfunction in the future. In addition, recent studies have shown that TMEM16A plays different roles in different diseases through different signal transduction pathways. This review discusses the topology, electrophysiological properties, modulators and functions of TMEM16A in mediates nociception, gastrointestinal dysfunction, hypertension, and cancer and focuses on multiple regulatory mechanisms regarding TMEM16A.

The HamE scaffold positively regulates MpkB phosphorylation to promote development and secondary metabolism in Aspergillus nidulans

Mitogen-activated protein kinase (MAPK) pathways are conserved signalling cascades in eukaryotes which regulate a myriad of processes in fungi from sexual reproduction to stress responses. These pathways rely on recruitment of three kinases on a scaffold protein to facilitate efficient kinase phosphorylation and subsequent downstream signalling to the nucleus. The model filamentous fungus Aspergillus nidulans utilises a MAPK pathway termed the pheromone module to regulate both development and secondary metabolism. This complex consists of the MAP3K (SteC), MAP2K (MkkB), MAPK (MpkB) and adaptor protein SteD. To date, there has been no scaffold protein identified for this MAPK pathway. In this study, we characterised a protein termed HamE, which we propose as a scaffold that regulates kinase phosphorylation and signalling in the pheromone module. Mass spectrometry analysis and BIFC experiments revealed that HamE physically interacts with both MkkB and MpkB and transiently interacts with SteC. Deletion of hamE or any of the pheromone module kinases results in reduced sporulation and complete abolishment of cleistothecia production. Mutants also exhibited reductions in expression of secondary metabolite gene clusters, including the velvet complex and sterigmatocystin genes. HamE acts as a positive regulator of MpkB phosphorylation, allowing for HamE to subsequently regulate development and secondary metabolism.

Redox for Repair: Cold Physical Plasmas and Nrf2 Signaling Promoting Wound Healing

Chronic wounds and ulcers are major public health threats. Being a substantial burden for patients and health care systems alike, better understanding of wound pathophysiology and new avenues in the therapy of chronic wounds are urgently needed. Cold physical plasmas are particularly effective in promoting wound closure, irrespective of its etiology. These partially ionized gases deliver a therapeutic cocktail of reactive oxygen and nitrogen species safely at body temperature and without genotoxic side effects. This field of plasma medicine reanimates the idea of redox repair in physiological healing. This review compiles previous findings of plasma effects in wound healing. It discusses new links between plasma treatment of cells and tissues, and the perception and intracellular translation of plasma-derived reactive species via redox signaling pathways. Specifically, (i) molecular switches governing redox-mediated tissue response; (ii) the activation of the nuclear E2-related factor (Nrf2) signaling, together with antioxidative and immunomodulatory responses; and (iii) the stabilization of the scaffolding function and actin network in dermal fibroblasts are emphasized in the light of wound healing.

Anisomycin, a JNK and p38 activator, suppresses cell-cell junction formation in 2D cultures of K38 mouse keratinocyte cells and reduces claudin-7 expression, with an increase of paracellular permeability in 3D cultures

Keratinocytes in the oral mucosal epithelium, which is a non-keratinized stratified epithelium, are exposed to various stimuli from the oral cavity. JNK and p38 are stress-activated mitogen-activated protein kinases (MAPKs) that are phosphorylated by various stimuli and are involved in the assembly and disassembly of tight junctions (TJs) in keratinocytes. Therefore, we investigated the effects of stress-activated MAPKs on TJs in a mouse keratinocyte cell line during cell-cell junction formation in two-dimensional (2D) cultures or stratification to form non-keratinized epithelium in 3D cultures. In 2D cultures, calcium induced zipper-like staining for ZO-1 at 2 h and string-like staining for ZO-1 at 12 h, which indicated immature and mature cell-cell junctions, respectively. Anisomycin (AM), a JNK and p38 activator, inhibited formation of string-like staining for ZO-1, whereas inhibition of JNK, but not p38, after AM treatment restored string-like staining for ZO-1, although claudins (CLDNs) 4, 6, and 7 did not completely colocalize to ZO-1-positive sites. In 3D cultures, AM treatment for 2 weeks activated only p38, suppressed flattening of the superficial cells, removed CLDN7 from ZO-1-positive spots on the surface of 3D cultures, which represent TJs, and decreased transepithelial electrical resistance. Thus, short-term AM treatment inhibited maturation of cell-cell junctions by JNK, but not p38, activation. p38 activation by long-term AM treatment affected morphology of stratified structures and paracellular permeability, which was increased by CLDN7 removal from TJs. Various chronic stimuli that activate stress-activated MAPKs may weaken the keratinocyte barrier and be involved in TJ-related diseases.

Spred negatively regulates lens growth by modulating epithelial cell proliferation and fiber differentiation

Spred, like Sprouty (Spry) and also Sef proteins, have been identified as important regulators of receptor tyrosine kinase (RTK)-mediated MAPK/ERK-signaling in various developmental systems, controlling cellular processes such as proliferation, migration and differentiation. Spreds are widely expressed during early embryogenesis, and in the eye lens, become more localised in the lens epithelium with later development, overlapping with other antagonists including Spry. Given the synexpression of Spreds and Spry in lens, in order to gain a better understanding of their specific roles in regulating growth factor mediated-signaling and cell behavior, we established and characterised lines of transgenic mice overexpressing Spred1 or Spred2, specifically in the lens. This overexpression of Spreds resulted in a small lens phenotype during ocular morphogenesis, retarding its growth by compromising epithelial cell proliferation and fiber differentiation. These in situ findings were shown to be dependent on the ability of Spreds to suppress MAPK-signaling, in particular FGF-induced ERK1/2-signaling in lens cells. This was validated in vitro using lens epithelial explants, that highlighted the overlapping role of Spreds with Spry2, but not Spry1. This study provides insights into the putative function of Spreds and Spry in situ, some overlapping and some distinct, and their importance in regulating lens cell proliferation and fiber differentiation contributing to lens and eye growth.

Isolation and identification of peptides from simulated gastrointestinal digestion of preserved egg white and their anti-inflammatory activity in TNF-α-induced Caco-2 cells

Simulated gastrointestinal digestion of preserved egg white (SGD-PEW) exerts anti-inflammatory effects on Caco-2 cells and a mouse model of DSS-induced colitis. Here, we aimed to separate peptides derived from SGD-PEW and evaluate their anti-inflammatory effects using an in vitro inflammatory model. Six peptides were isolated and identified. DEDTQAMPFR (DR-10), DEDTQAMPF (DF-9), MLGATSL (ML-7) and MSYSAGF (MF-7) significantly inhibited IL-8 secretion and markedly decreased gene expression, including TNF-α, IL-8, IL-6, IL-1β and IL-12 and promoted IL-10 gene expression in Caco-2 cells. DR-10, DF-9, ML-7 and MF-7 significantly inhibited the phosphorylation of JNK. In the meantime, DR-10 and DF-9 significantly reduced the phosphorylation of IκB and p38. These results indicated that ML-7 and MF-7 exerted their anti-inflammatory activity through the MAPK signaling pathway in TNF-α-induced Caco-2 cells. Whereas, DR-10 and DF-9 inhibited the NF-κB and MAPK signaling pathways. The results suggested that DR-10, DF-9, ML-7 and MF-7 derived from SGD-PEW may be a new type of prophylactic food for the treatment of inflammation.

Stochasticity and robustness analysis of microRNA-mediated ERK signaling network

MicroRNAs (miRNAs) play a critical role in regulating the signaling network such as the extracellular signal regulated kinase (ERK) pathway. However, the mechanisms of miRNA-mediated posttranscriptional regulations with regard to their impacts on signaling require further investigation from a systematic level. Therefore, we develop a mathematical model by analyzing the precise dynamic mechanisms with a bevy of miRNAs involved in the Ras/Raf/MEK/ERK pathway. A systems-based analysis approach is introduced into this model and the dynamics have been implemented deterministically and stochastically. Our analysis reveals that miRNAs are key participants regulating the gene expression of ERK network, and the cooperative actions of miRNAs are important in keeping the normal biological characteristics and amplification effects of the system. Meanwhile, the appearance of system disorder in the absence of miRNAs suggests that miRNAs may play a role in the pathological processes, such as tumor and inflammation. The sensitivity analysis and the kinetic parameter perturbation show that the binding of receptor (EGFR) and adaptor protein (Shc, Grb2 and Sos) under normal physiological conditions is crucial for the robustness of the whole pathway. In addition, the stochastic dynamic patterns are in a good agreement with the deterministic results, further demonstrating that the variability of the system due to the presence of some stochastic noise is low. All these will be helpful for a deeper understanding of the dynamic mechanism of miRNA-mediated ERK signal network, which might present a rich area of future research with the relevant regulatory roles of miRNAs in cell signaling pathway.

Epigenetic and Posttranslational Modifications in Regulating the Biology of Aspergillus Species

Epigenetic and posttranslational modifications have been proved to participate in multiple cellular processes and suggested to be an important regulatory mechanism on transcription of genes in eukaryotes. However, our knowledge about epigenetic and posttranslational modifications mainly comes from the studies of yeasts, plants, and animals. Recently, epigenetic and posttranslational modifications have also raised concern for the relevance of regulating fungal biology in Aspergillus. Emerging evidence indicates that these modifications could be a connection between genetic elements and environmental factors, and their combined effects may finally lead to fungal phenotypical changes. This article describes the advances in typical DNA and protein modifications in the genus Aspergillus, focusing on methylation, acetylation, phosphorylation, ubiquitination, sumoylation, and neddylation.

In silico-in vitro discovery of untargeted kinase-inhibitor interactions from kinase-targeted therapies: A case study on the cancer MAPK signaling pathway

Protein kinase inhibitors have been widely used as therapeutic agents to treat a variety of diseases, but many of them may cause off-target effects by unexpectedly targeting other noncognate kinases due to high conversion across the protein kinase family. The mitogen-activated protein kinase (MAPK) signaling pathway plays an essential role in tumorigenesis, which has been recognized as a high priority in the druggable target candidates of anticancer therapy. Here, we attempt to investigate the untargeted kinase-inhibitor interactions (UKIIs) of kinase-targeted therapies for the cancer MAPK signaling cascade via an integration of biomolecular modeling, cell viability assay and kinase inhibition analysis. A systematic kinase-inhibitor interaction profile is created for 28 FDA-approved kinase inhibitor drugs across 9 caner-related MAPK kinases. The created profile is analyzed at structural, energetic and dynamic levels and, consequently, totally 18 promising UKII pairs with high theoretical affinity are derived, from which the noncognate inhibitors Cabozantinib, Regorafenib and Crizotinib are selected to test their cytotoxic effects on human epithelial colorectal adenocarcinoma Caco-2 cell line and inhibition activity against the recombinant protein of human p38α kinase domain. The obtained results are compared with two cognate MAPK inhibitors JNK-IN-8 and BIRB796. As might be expected, the Regorafenib, Crizotinib and Cabozantinib exhibit high, moderate and low cytotoxicities, respectively. In addition, the Regorafenib is determined to have a potent p38α-inhibitory activity. This is basically in line with the test results of positive controls JNK-IN-8 and BIRB796 and can be well confirmed by computational modeling.

MAP kinase Slt2 orthologs play similar roles in conidiation, trap formation, and pathogenicity in two nematode-trapping fungi

Mitogen-activated protein (MAP) kinase Slt2 is a key player in the cell-wall integrity pathway of budding yeast. In this study, we functionally characterized Slt2 orthologs AoSlt2 and MhSlt2 from the nematode-trapping fungi Arthrobotrys oligospora and Monacrosporium haptotylum, respectively. We found that disruption of AoSlt2 and MhSlt2 led to reduced mycelial growth, increased sensitivity to environmental stresses such as sodium dodecyl sulfate, Congo red, and H₂O₂, and an inability to produce conidia and nematode-trapping structures. Real-time polymerase chain reaction-based analyses showed that the transcription of sporulation-related (AbaA, Sep2, and MedA) and cell wall synthesis-related (Chs, Glu, and Gfpa) genes was down-regulated in the mutants compared with the wild-type strains. Moreover, the mutant strains showed reduced extracellular proteolytic activity and decreased transcription of three homologous serine protease-encoding genes. These results show for the first time that MAP kinase Slt2 orthologs play similar roles in regulating mycelial growth, conidiation, trap formation, stress resistance, and pathogenicity in the divergent nematode-trapping fungal species A. oligospora and M. haptotylum.

miR-3188 Regulates Cell Proliferation, Apoptosis, and Migration in Breast Cancer by Targeting TUSC5 and Regulating the p38 MAPK Signaling Pathway

This study intended to investigate the effects of miR-3188 on breast cancer and to reveal the possible molecular mechanisms. miR-3188 was upregulated and TUSC5 was downregulated in breast cancer tissues and MCF-7 cells compared to normal tissue and MCF-10 cells. After MCF-7 cells were transfected with miR-3188 inhibitor, cell proliferation and migration were inhibited, whereas apoptosis was promoted. Luciferase reporter assay suggested that TUSC5 was a target gene of miR-3188. In addition, miR-3188 overexpression increased the p-p38 expression, while miR-3188 suppression decreased the p-p38 expression significantly. miR-3188 regulated breast cancer progression via the p38 MAPK signaling pathway. In conclusion, miR-3188 affects breast cancer cell proliferation, apoptosis, and migration by targeting TUSC5 and activating the p38 MAPK signaling pathway. miR-3188 may serve as a potential therapeutic agent for the treatment of breast cancer.

Spotlight on dabrafenib/trametinib in the treatment of non-small-cell lung cancer: place in therapy

Advanced non-small-cell lung cancer (NSCLC) remains a challenging disease. The limited utility of chemotherapy indicates the need for additional therapeutic options. Targeted therapy continues to be an important tool in the treatment of NSCLC. Mutations within the RAS–RAF–MEK–MAPK pathway, specifically the BRAF V600E mutation, have become an important target for the subset of NSCLC patients with this mutation. This paper summarizes the clinical evidence that lead to the recent approval of the combination of dabrafenib and trametinib to treat patients with advanced NSCLC who harbor a BRAF V600E mutation.

Cellular response to persistent foot-and-mouth disease virus infection is linked to specific types of alterations in the host cell transcriptome

Food-and-mouth disease virus (FMDV) is a highly contagious virus that seriously threatens the development of animal husbandry. Although persistent FMDV infection can dramatically worsen the situation, the mechanisms involved in persistent FMDV infection remain unclear. In the present study, we identified the presence of evolved cells in the persistently FMDV-infected cell line. These cells exhibited resistance to the parent FMDV and re-established persistent infection when infected with FMDV-Op (virus supernatant of persistent infection cell lines), emphasizing the decisive role of evolved host cells in the establishment of persistent FMDV infection. Using RNA-seq, we identified the gene expression profiles of these evolved host cells. In total, 4,686 genes were differentially expressed in evolved cells compared with normal cells, with these genes being involved in metabolic processes, cell cycle, and cellular protein catabolic processes. In addition, 1,229 alternative splicing events, especially skipped exon events, were induced in evolved cells. Moreover, evolved cells exhibited a stronger immune defensive response and weaker MAPK signal response than normal cells. This comprehensive transcriptome analysis of evolved host cells lays the foundation for further investigations of the molecular mechanisms of persistent FMDV infection and screening for genes resistant to FMDV infection.

Recent Insights into the Contribution of the Changing Hypertrophic Chondrocyte Phenotype in the Development and Progression of Osteoarthritis

Osteoarthritis (OA) is an extremely prevalent age-related condition. The economic and societal burden due to the cost of symptomatic treatment, inability to work, joint replacement, and rehabilitation is huge and increasing. Currently, there are no effective medical therapies that delay or reverse the pathological manifestations of OA. Current treatment options are, without exception, focused on slowing down progression of the disease to postpone total joint replacement surgery for as long as possible and keeping the associated pain and joint immobility manageable. Alterations in the articular cartilage chondrocyte phenotype might be fundamental in the pathological mechanisms of OA development. In many ways, the changing chondrocyte phenotype in osteoarthritic cartilage resembles the process of endochondral ossification as seen, for instance, in developing growth plates. However, the relative contribution of endochondral ossification to the changing chondrocyte phenotype in the development and progression of OA remains poorly described. In this review, we will discuss the current knowledge regarding the cartilage endochondral phenotypic changes occurring during OA development and progression, as well as the molecular and environmental effectors driving these changes. Understanding how these molecular mechanisms determine the chondrocyte cell fate in OA will be essential in enabling cartilage regenerative approaches in future treatments of OA.

Extracellular-Regulated Kinases: Signaling From Ras to ERK Substrates to Control Biological Outcomes

The extracellular-regulated kinases ERK1 and ERK2 are evolutionarily conserved, ubiquitous serine-threonine kinases that are involved in regulating cellular signaling in both normal and pathological conditions. Their expression is critical for development and their hyperactivation is a major factor in cancer development and progression. Since their discovery as one of the major signaling mediators activated by mitogens and Ras mutation, we have learned much about their regulation, including their activation, binding partners and substrates. In this review I will discuss some of what has been discovered about the members of the Ras to ERK pathway, including regulation of their activation by growth factors and cell adhesion pathways. Looking downstream of ERK activation I will also highlight some of the many ERK substrates that have been discovered, including those involved in feedback regulation, cell migration and cell cycle progression through the control of transcription, pre-mRNA splicing and protein synthesis.

Enhanced antitumor activity of combined megestrol acetate and arsenic trioxide treatment in liver cancer cells

Liver cancer is an aggressive malignancy with a very high fatality rate. Although megestrol acetate (MA) and arsenic trioxide (ATO) have shown an antitumor effect in liver cancer cells, the therapeutic benefits of MA or ATO alone in patients with liver cancer were limited. The aim of the present study was to elucidate whether the co-treatment of MA/ATO could enhance antitumor efficacy in liver cancer cell lines (Hep G2 and BEL 7402) and explore the underlying anti-cancer mechanisms. The cell viability, apoptotic response and expression levels of associated proteins were detected by Cell Counting Kit-8 assay, flow cytometry and western blotting, respectively. An xenograft model in nude mice bearing a Hep G2 tumor was used to estimate tumor growth in vivo. Co-treatment with MA/ATO markedly improved the inhibition of cell viability, enhanced apoptosis, and increased the phosphorylation of p38, c-Jun N-terminal kinase 1/2 and extracellular signal-regulated kinase 1/2 on liver cancer cell lines. Furthermore, the tumor growth in the murine Hep G2 cancer xenograft model was significantly inhibited by combined treatment with MA/ATO. The results indicated that MA/ATO combined treatment enhanced antitumor efficacy and possessed potential application for treating liver cancer.

Losmapimod Overcomes Gefitinib Resistance in Non-small Cell Lung Cancer by Preventing Tetraploidization

The epidermal growth factor receptor (EGFR) is known to play a critical role in non-small cell lung cancer (NSCLC). Constitutively active EGFR mutations, including in-frame deletion in exon 19 and L858R point mutation in exon 21, contribute about 90% of all EGFR-activating mutations in NSCLC. Although oral EGFR-tyrosine kinase inhibitors (TKIs), gefitinib and erlotinib, show dramatic clinical efficacy with significantly prolonged progression-free survival in patients harboring these EGFR-activating mutations, most of these patients will eventually develop acquired resistance. Researchers have recently named genomic instability as one of the hallmarks of cancer. Genomic instability usually involves a transient phase of polyploidization, in particular tetraploidization. Tetraploid cells can undergo asymmetric cell division or chromosome loss, leading to tumor heterogeneity and multidrug resistance. Therefore, identification of signaling pathways involved in tetraploidization is crucial in overcoming drug resistance. In our present study, we found that gefitinib could activate YAP-MKK3/6-p38 MAPK-STAT3 signaling and induce tetraploidization in gefitinib-resistance cells. Using p38 MAPK inhibitors, SB203580 and losmapimod, we could eliminate gefitinib-induced tetraploidization and overcome gefitinib-resistance. In addition, shRNA approach to knockdown p38α MAPK could prevent tetraploidy formation and showed significant inhibition of cancer cell growth. Finally, in an in vivo study, losmapimod could successfully overcome gefitinib resistance using an in-house established patient-derived xenograft (PDX) mouse model. Overall, these findings suggest that losmapimod could be a potential clinical agent to overcome gefitinib resistance in NSCLC.

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Gefitinib induces tetraploidy formation in gefitinib-resistant NSCLC cells

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YAP-MKK3/6-p38 MAPK signaling is essential for tetraploidization

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Losmapimod, a p38 MAPK inhibitor, overcomes gefitinib-resistance both in vitro and PDX xenograft mode

Gefitinib is a targeted drug therapy in non-small cell lung cancer (NSCLC) which shows dramatic clinical efficacy. However, most of these patients eventually develop drug resistance. Although researchers have identified different mechanisms contributing to the drug resistance, developing a single therapy to overcome the drug resistance remains difficult. In this study, we find that tetraploidization of cancer cells through YAP-MKK3/6-p38 MAPK signaling could be one of the common mechanisms in developing the drug resistance. By using losmapimod, we could eliminate tetraploidization and overcome gefitinib resistance in an animal model suggesting that losmapimod could be a potential clinical agent to overcome gefitinib resistance in NSCLC.

Stress-activated MAPKs and CRM1 regulate the subcellular localization of Net1A to control cell motility and invasion

The neuroepithelial cell transforming gene 1A (Net1A, an isoform of Net1) is a RhoA subfamily guanine nucleotide exchange factor (GEF) that localizes to the nucleus in the absence of stimulation, preventing it from activating RhoA. Once relocalized in the cytosol, Net1A stimulates cell motility and extracellular matrix invasion. In the present work, we investigated mechanisms responsible for the cytosolic relocalization of Net1A. We demonstrate that inhibition of MAPK pathways blocks Net1A relocalization, with cells being most sensitive to JNK pathway inhibition. Moreover, activation of the JNK or p38 MAPK family pathway is sufficient to elicit Net1A cytosolic localization. Net1A relocalization stimulated by EGF or JNK activation requires nuclear export mediated by CRM1. JNK1 (also known as MAPK8) phosphorylates Net1A on serine 52, and alanine substitution at this site prevents Net1A relocalization caused by EGF or JNK activation. Glutamic acid substitution at this site is sufficient for Net1A relocalization and results in elevated RhoA signaling to stimulate myosin light chain 2 (MLC2, also known as MYL2) phosphorylation and F-actin accumulation. Net1A S52E expression stimulates cell motility, enables Matrigel invasion and promotes invadopodia formation. These data highlight a novel mechanism for controlling the subcellular localization of Net1A to regulate RhoA activation, cell motility, and invasion.

Key Age-Imposed Signaling Changes That Are Responsible for the Decline of Stem Cell Function

This chapter analyzes recent developments in the field of signal transduction of ageing with the focus on the age-imposed changes in TGF-beta/pSmad, Notch, Wnt/beta-catenin, and Jak/Stat networks. Specifically, this chapter delineates how the above-mentioned evolutionary-conserved morphogenic signaling pathways operate in young versus aged mammalian tissues, with insights into how the age-specific broad decline of stem cell function is precipitated by the deregulation of these key cell signaling networks. This chapter also provides perspectives onto the development of defined therapeutic approaches that aim to calibrate intensity of the determinant signal transduction to health-youth, thereby rejuvenating multiple tissues in older people.

Discovery of 2-arylquinazoline derivatives as a new class of ASK1 inhibitors

The development of a new series of apoptosis signal-regulating kinase 1 (ASK1) inhibitors is described. Starting from purine, pyrimidine and quinazoline scaffolds identified by high throughput screening, we used tools of structure-based drug design to develop a series of potent kinase inhibitors, including 2-arylquinazoline derivatives 12 and 23, with submicromolar inhibitory activities against ASK1. Kinetic analysis demonstrated that the 2-arylquinazoline scaffold ASK1 inhibitors described herein are ATP competitive.

Role of MAPK Signaling Pathways in Regulating the Hydrophobin Cryparin in the Chestnut Blight Fungus Cryphonectria parasitica

We assessed the regulation of cryparin, a class II hydrophobin, using three representative mitogen-activated protein kinase (MAPK) pathways in Cryphonectria parasitica. Mutation of the CpSlt2 gene, an ortholog of yeast SLT2 in the cell wall integrity (CWI) pathway, resulted in a dramatic decrease in cryparin production. Similarly, a mutant of the CpBck1 gene, a MAP kinase kinase kinase gene in the CWI pathway, showed decreased cryparin production. Additionally, mutation of the cpmk1 gene, an ortholog of yeast HOG1, showed decreased cryparin production. However, mutation of the cpmk2 gene, an ortholog of yeast Kss1/Fus3, showed increased cryparin production. The easy-wet phenotype and accumulation of the cryparin transcript in corresponding mutants were consistent with the cryparin production results. In silico analysis of the promoter region of the cryparin gene revealed the presence of binding motifs related to downstream transcription factors of CWI, HOG1, and pheromone responsive pathways including MADS-box- and Ste12-binding domains. Real-time reverse transcriptase PCR analyses indicated that both CpRlm1, an ortholog of yeast RLM1 in the CWI pathway, and cpst12, an ortholog of yeast STE12 in the mating pathway, showed significantly reduced transcription levels in the mutant strains showing lower cryparin production in C. prasitica. However, the transcription of CpMcm1, an ortholog of yeast MCM1, did not correlate with that of the mutant strains showing downregulation of cryparin. These results indicate that three representative MAPK pathways played a role in regulating cryparin production. However, regulation varied depending on the MAPK pathways: the CWI and HOG1 pathways were stimulatory, whereas the pheromone-responsive MAPK was repressive.

Anti‑inflammatory effect of quercetin and galangin in LPS‑stimulated RAW264.7 macrophages and DNCB‑induced atopic dermatitis animal models

Flavonols are compounds that have been shown to possess potent anti-inflammatory effects in cellular and animal models of inflammation. In the present study, the anti-inflammatory effects and mechanisms of two natural flavonols, quercetin and galangin, in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages were investigated. It was identified that quercetin and galangin markedly reduced the production of nitric oxide (NO), inducible NO synthase and interleukin-6, and the nuclear translocation of nuclear factor-κB (NF-κB). In addition, LPS-induced activation of extracellular signal-regulated kinase 1/2 (Erk1/2) and c-Jun N-terminal kinase (JNK) was suppressed by quercetin and galangin. Taken together, these data implied that NF-κB, Erk1/2 and JNK may be potential molecular targets of quercetin and galangin in an LPS-induced inflammatory response. Subsequently, the effects of oral administration of quercetin or galangin, either alone or in combination, in a 2,4-dinitrochlorobenzene-induced atopic dermatitis (AD) mouse model were investigated. As a result, measurements of ear thickness and the levels of serum immunoglobulin E, and histological analysis revealed that the two flavonols led to a decrease in inflammation, whereas, in combination, they were even more effective. These results suggested that quercetin and galangin may be promising therapeutic agents for AD. Additionally, their combination may be a novel therapeutic strategy for the prevention of AD.

Activation of Group II Metabotropic Glutamate Receptors Increases Proliferation but does not Influence Neuronal Differentiation of a Human Neural Stem Cell Line

The multiple functions of glutamate include regulation of neural development and stem cells. While the importance of the ionotropic glutamate receptors is well-established, less is known about the role of metabotropic glutamate receptors (mGluRs). In this study, we examined the effects of pharmacological activation and inhibition of mGluR2/3 on proliferation, differentiation and viability of a human neural stem cell line. Immunofluorescence staining revealed the presence of mGluR2/3 receptors on both proliferating and differentiating stem cells, including cells differentiated into β-tubulin III-positive immature neurons and glial fibrillary acidic protein-positive astrocytes. Stimulation of mGluR2/3 receptors during cell propagation using the agonist (2S,2'R,3'R)-2-(2',3'-dicarboxycyclopropyl) glycine (DCG-IV) increased total cell numbers significantly (60% compared to untreated controls). This effect could be inhibited by the specific antagonist (2S)-2-Amino-2-[(1S,2S)-2-carboxycycloprop-1-yl]-3-(xanth-9-yl) propanoic acid (LY341495). The antagonist alone had no effect. No significant decrease in cell death was found following mGluR2/3 stimulation, suggesting that the observed elevation in cell number was not related to cell viability. Subsequent differentiation of the cells resulted in a slight decrease in β-tubulin III-positive neurons (5.2-3.2% of total cells) for DCG-IV pre-treated cultures. Treatment with DCG-IV and LY342495 during cell differentiation alone had no such effect. Western blot analysis revealed that the active, dimeric form of mGluR2/3 was mainly present on the proliferating cells, which may explain our findings. This study emphasizes the importance of glutamate and mGluRs on regulation of human neural stem cells and suggests a significant role of mGluR2/3 during cell proliferation.

Genistein inhibits the growth and regulates the migration and invasion abilities of melanoma cells via the FAK/paxillin and MAPK pathways

Genistein is one of the main components of soy-based foods, which are widely known for their many benefits, including anti-cancer, anti-inflammatory, and antioxidant effects. In this study, we investigated the anti-metastasis effects of genistein on B16F10 melanoma cells. Our results showed that genistein strongly inhibited B16F10 cell proliferation and induced apoptosis in time- and concentration-dependent manners. Genistein altered the morphology of B16F10 cells to an elongated shape with slim pseudopodia-like protrusions. Moreover, genistein inhibited the invasion and migration abilities of B16F10 cells in a dose-dependent manner. On one hand, a high concentration of genistein (100 μM) significantly inhibited cell adhesion and migration, as shown by wound healing assays and transwell-migration and invasion assays. Furthermore, the expression levels of p-FAK, p-paxillin, tensin-2, vinculin, and α-actinin were decreased by genistein. As a result, genistein is believed to strongly downregulate the migration and invasion abilities of B16F10 cells via the FAK/paxillin pathway. Moreover, p-p38, p-ERK, and p-JNK levels were also dramatically decreased by treatment with genistein. Finally, genistein significantly decreased the gene expression of FAK, paxillin, vimentin, and epithelial-to-mesenchymal transition-related transcription factor Snail, as shown by real-time PCR (qPCR) analysis. On the other hand, a lower concentration of genistein (12.5 μM) significantly promoted both invasion and migration by activating the FAK/paxillin and MAPK signaling cascades. Taken together, this study showed for the first time that genistein exerts dual functional effects on melanoma cells. Our findings suggest that genistein regulates the FAK/paxillin and MAPK signaling pathways in a highly concentration-dependent manner. Patients with melanoma should therefore be cautious of consuming soy-based foods in their diets.