Extracellular signal-regulated kinase (ERK) is a part of the mitogen-activated protein kinase (MAPK) signaling pathway which allows the transduction of various cellular signals to final effectors and regulation of elementary cellular processes. Deregulation of the MAPK signaling occurs under many pathological conditions including neurodegenerative disorders, metabolic syndromes and cancers. Targeted inhibition of individual kinases of the MAPK signaling pathway using synthetic compounds represents a promising way to effective anti-cancer therapy. Cross-talk of the MAPK signaling pathway with other proteins and signaling pathways have a crucial impact on clinical outcomes of targeted therapies and plays important role during development of drug resistance in cancers. We discuss cross-talk of the MAPK/ERK signaling pathway with other signaling pathways, in particular interplay with the Hippo/MST pathway. We demonstrate the mechanism of cell death induction shared between MAPK/ERK and Hippo/MST signaling pathways and discuss the potential of combination targeting of these pathways in the development of more effective anti-cancer therapies.

• Keywords
• ERK, Hippo, MAPK, MST, PI3K, YAP, apoptosis, cancer, caspase, inhibitors, natural compounds, therapy,
• MeSH
• Extracellular Signal-Regulated MAP Kinases antagonists & inhibitors   metabolism   MeSH
• Protein Kinase Inhibitors therapeutic use   MeSH
• Humans MeSH
• Neoplasms drug therapy   metabolism   MeSH
• Protein Serine-Threonine Kinases antagonists & inhibitors   metabolism   MeSH
• Antineoplastic Agents therapeutic use   MeSH
• Hippo Signaling Pathway MeSH
• Signal Transduction MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Extracellular Signal-Regulated MAP Kinases MeSH
• Protein Kinase Inhibitors MeSH
• Protein Serine-Threonine Kinases MeSH
• Antineoplastic Agents MeSH

The limited information available on the structure of complexes involving transcription factors and cognate DNA response elements represents a major obstacle in the quest to understand their mechanism of action at the molecular level. We implemented a concerted structural proteomics approach, which combined hydrogen-deuterium exchange (HDX), quantitative protein-protein and protein-nucleic acid cross-linking (XL), and homology analysis, to model the structure of the complex between the full-length DNA binding domain (DBD) of Forkhead box protein O4 (FOXO4) and its DNA binding element (DBE). The results confirmed that FOXO4-DBD assumes the characteristic forkhead topology shared by these types of transcription factors, but its binding mode differs significantly from those of other members of the family. The results showed that the binding interaction stabilized regions that were rather flexible and disordered in the unbound form. Surprisingly, the conformational effects were not limited only to the interface between bound components, but extended also to distal regions that may be essential to recruiting additional factors to the transcription machinery. In addition to providing valuable new insights into the binding mechanism, this project provided an excellent evaluation of the merits of structural proteomics approaches in the investigation of systems that are not directly amenable to traditional high-resolution techniques.

• Keywords
• DNA, FOXO4, cross-linking, molecular modeling, protein, protein-nucleic acid cross-linking, trans-dichlorodiamineplatinum(II), hydrogen-deuterium exchange, transcription factor, transplatin,
• MeSH
• DNA-Binding Proteins chemistry   metabolism   MeSH
• DNA chemistry   metabolism   MeSH
• Mass Spectrometry MeSH
• Molecular Structure MeSH
• Response Elements MeSH
• Transcription Factors chemistry   metabolism   MeSH
• Deuterium Exchange Measurement MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Research Support, N.I.H., Extramural MeSH
• Names of Substances
• DNA-Binding Proteins MeSH
• DNA MeSH
• Transcription Factors MeSH

The discrete activation of individual caspases is essential during T-cell development, activation, and apoptosis. Humans carrying nonfunctional caspase-8 and caspase-8 conditional knockout mice exhibit several defects in the progression of naive CD4⁺ T cells to the effector stage. MST1, a key kinase of the Hippo signaling pathway, is often presented as a substrate of caspases, and its cleavage by caspases potentiates its activity. Several studies have focused on the involvement of MST1 in caspase activation and also reported several defects in the immune system function caused by MST1 deficiency. Here, we show the rapid activation of the MEK-ERK-MST1 axis together with the cleavage and activation of caspase-3, -6, -7, -8, and -9 after PI3K signaling blockade by the selective inhibitor GDC-0941 in Jurkat T cells. We determined the phosphorylation pattern of MST1 using a phosphoproteomic approach and identified two amino acid residues phosphorylated in an ERK-dependent manner after GDC-0941 treatment together with a novel phosphorylation site at S21 residue, which was extensively phosphorylated in an ERK-independent manner during PI3K signaling blockade. Using caspase inhibitors and the inhibition of MST1 expression using siRNA, we identified an exclusive role of the MEK-ERK-MST1 axis in the activation of initiator caspase-8, which in turn activates executive caspase-3/-7 that finally potentiate MST1 proteolytic cleavage. This mechanism forms a positive feed-back loop that amplifies the activation of MST1 together with apoptotic response in Jurkat T cells during PI3K inhibition. Altogether, we propose a novel MEK-ERK-MST1-CASP8-CASP3/7 apoptotic pathway in Jurkat T cells and believe that the regulation of this pathway can open novel possibilities in systemic and cancer therapies.

• Keywords
• AKT, ERK, Hippo/MST1, MEK, PI3K, apoptosis, caspase,
• MeSH
• Enzyme Activation drug effects   MeSH
• Apoptosis drug effects   MeSH
• Models, Biological MeSH
• Down-Regulation drug effects   MeSH
• Phosphatidylinositol 3-Kinases metabolism   MeSH
• Phosphorylation drug effects   MeSH
• Phosphothreonine metabolism   MeSH
• Hepatocyte Growth Factor chemistry   metabolism   MeSH
• Indazoles pharmacology   MeSH
• Phosphoinositide-3 Kinase Inhibitors MeSH
• Caspase Inhibitors pharmacology   MeSH
• Jurkat Cells MeSH
• Caspases metabolism   MeSH
• Humans MeSH
• MAP Kinase Signaling System drug effects   MeSH
• Mitogen-Activated Protein Kinase Kinases metabolism   MeSH
• Piperazines pharmacology   MeSH
• Proteolysis drug effects   MeSH
• Proto-Oncogene Proteins chemistry   metabolism   MeSH
• Amino Acid Sequence MeSH
• Sulfonamides pharmacology   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• 2-(1H-indazol-4-yl)-6-(4-methanesulfonylpiperazin-1-ylmethyl)-4-morpholin-4-ylthieno(3,2-d)pyrimidine MeSH Browser
• Phosphothreonine MeSH
• Hepatocyte Growth Factor MeSH
• Indazoles MeSH
• Phosphoinositide-3 Kinase Inhibitors MeSH
• Caspase Inhibitors MeSH
• Caspases MeSH
• macrophage stimulating protein MeSH Browser
• Mitogen-Activated Protein Kinase Kinases MeSH
• Piperazines MeSH
• Proto-Oncogene Proteins MeSH
• SCH772984 MeSH Browser
• Sulfonamides MeSH

Abnormalities in cancer metabolism represent potential targets for cancer therapy. We have recently identified a natural compound Quambalarine B (QB), which inhibits proliferation of several leukemic cell lines followed by cell death. We have predicted ubiquinone binding sites of mitochondrial respiratory complexes as potential molecular targets of QB in leukemia cells. Hence, we tracked the effect of QB on leukemia metabolism by applying several omics and biochemical techniques. We have confirmed the inhibition of respiratory complexes by QB and found an increase in the intracellular AMP levels together with respiratory substrates. Inhibition of mitochondrial respiration by QB triggered reprogramming of leukemic cell metabolism involving disproportions in glycolytic flux, inhibition of proteins O-glycosylation, stimulation of glycine synthesis pathway, and pyruvate kinase activity, followed by an increase in pyruvate and a decrease in lactate levels. Inhibition of mitochondrial complex I by QB suppressed folate metabolism as determined by a decrease in formate production. We have also observed an increase in cellular levels of several amino acids except for aspartate, indicating the dependence of Jurkat (T-ALL) cells on aspartate synthesis. These results indicate blockade of mitochondrial complex I and II activity by QB and reduction in aspartate and folate metabolism as therapeutic targets in T-ALL cells. Anti-cancer activity of QB was also confirmed during in vivo studies, suggesting the therapeutic potential of this natural compound.

• Keywords
• leukemia, metabolism, mitochondria, naphthoquinones, therapy,
• Publication type
• Journal Article MeSH

Malignant progression is greatly affected by dynamic cross-talk between stromal and cancer cells. Exosomes are secreted nanovesicles that have key roles in cell-cell communication by transferring nucleic acids and proteins to target cells and tissues. Recently, MicroRNAs (miRs) and their delivery in exosomes have been implicated in physiological and pathological processes. Tumor-delivered miRs, interacting with stromal cells in the tumor microenvironment, modulate tumor progression, angiogenesis, metastasis and immune escape. Altered cell metabolism is one of the hallmarks of cancer. A number of different types of tumor rely on mitochondrial metabolism by triggering adaptive mechanisms to optimize their oxidative phosphorylation in relation to their substrate supply and energy demands. Exogenous exosomes can induce metabolic reprogramming by restoring the respiration of cancer cells and supress tumor growth. The exosomal miRs involved in the modulation of cancer metabolism may be potentially utilized for better diagnostics and therapy.

• MeSH
• Biological Transport MeSH
• Stromal Cells metabolism   MeSH
• Energy Metabolism MeSH
• Exosomes genetics   MeSH
• Genetic Therapy MeSH
• Humans MeSH
• Cell Communication MeSH
• MicroRNAs genetics   MeSH
• Cell Line, Tumor MeSH
• Tumor Microenvironment genetics   MeSH
• Neoplasms genetics   metabolism   pathology   therapy   MeSH
• Gene Expression Regulation, Neoplastic MeSH
• Signal Transduction MeSH
• Gene Transfer Techniques MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• MicroRNAs MeSH

Biological systems are hierarchically self-organized complex structures characterized by nonlinear interactions. Biochemical energy is transformed into work of physical forces required for various biological functions. We postulate that energy transduction depends on endogenous electrodynamic fields generated by microtubules. Microtubules and mitochondria colocalize in cells with microtubules providing tracks for mitochondrial movement. Besides energy transformation, mitochondria form a spatially distributed proton charge layer and a resultant strong static electric field, which causes water ordering in the surrounding cytosol. These effects create conditions for generation of coherent electrodynamic field. The metabolic energy transduction pathways are strongly affected in cancers. Mitochondrial dysfunction in cancer cells (Warburg effect) or in fibroblasts associated with cancer cells (reverse Warburg effect) results in decreased or increased power of the generated electromagnetic field, respectively, and shifted and rebuilt frequency spectra. Disturbed electrodynamic interaction forces between cancer and healthy cells may favor local invasion and metastasis. A therapeutic strategy of targeting dysfunctional mitochondria for restoration of their physiological functions makes it possible to switch on the natural apoptotic pathway blocked in cancer transformed cells. Experience with dichloroacetate in cancer treatment and reestablishment of the healthy state may help in the development of novel effective drugs aimed at the mitochondrial function.

• MeSH
• Models, Biological * MeSH
• Electromagnetic Fields * MeSH
• Humans MeSH
• Mitochondria radiation effects   MeSH
• Cell Transformation, Neoplastic radiation effects   MeSH
• Neoplasms physiopathology   MeSH
• Energy Transfer * MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

AIMS: A plausible strategy to reduce tumor progress is the inhibition of angiogenesis. Therefore, agents that efficiently suppress angiogenesis can be used for tumor suppression. We tested the antiangiogenic potential of a mitochondrially targeted analog of α-tocopheryl succinate (MitoVES), a compound with high propensity to induce apoptosis. RESULTS: MitoVES was found to efficiently kill proliferating endothelial cells (ECs) but not contact-arrested ECs or ECs deficient in mitochondrial DNA, and suppressed angiogenesis in vitro by inducing accumulation of reactive oxygen species and induction of apoptosis in proliferating/angiogenic ECs. Resistance of arrested ECs was ascribed, at least in part, to the lower mitochondrial inner transmembrane potential compared with the proliferating ECs, thus resulting in the lower level of mitochondrial uptake of MitoVES. Shorter-chain homologs of MitoVES were less efficient in angiogenesis inhibition, thus suggesting a molecular mechanism of its activity. Finally, MitoVES was found to suppress HER2-positive breast carcinomas in a transgenic mouse as well as inhibit tumor angiogenesis. The antiangiogenic efficacy of MitoVES was corroborated by its inhibitory activity on wound healing in vivo. INNOVATION AND CONCLUSION: We conclude that MitoVES, a mitochondrially targeted analog of α-tocopheryl succinate, is an efficient antiangiogenic agent of potential clinical relevance, exerting considerably higher activity than its untargeted counterpart. MitoVES may be helpful against cancer but may compromise wound healing.

• MeSH
• alpha-Tocopherol analogs & derivatives   pharmacology   therapeutic use   MeSH
• Apoptosis drug effects   MeSH
• Cell Line MeSH
• Endothelial Cells drug effects   MeSH
• Wound Healing drug effects   MeSH
• Angiogenesis Inhibitors chemistry   pharmacology   therapeutic use   MeSH
• Humans MeSH
• DNA, Mitochondrial metabolism   MeSH
• Mitochondria drug effects   MeSH
• Disease Models, Animal MeSH
• Mice, Transgenic MeSH
• Mice MeSH
• Neoplasms blood supply   drug therapy   MeSH
• Neovascularization, Pathologic drug therapy   MeSH
• Cell Proliferation drug effects   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Mice MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Research Support, N.I.H., Extramural MeSH
• Names of Substances
• alpha-Tocopherol MeSH
• Angiogenesis Inhibitors MeSH
• DNA, Mitochondrial MeSH