GSK-3 and mitochondria in cancer cells

The Molecular Mechanisms behind Advanced Breast Cancer Metabolism: Warburg Effect, OXPHOS, and Calcium

Altered metabolism represents a fundamental difference between cancer cells and normal cells. Cancer cells have a unique ability to reprogram their metabolism by deviating their reliance from primarily oxidative phosphorylation (OXPHOS) to glycolysis, in order to support their survival. This metabolic phenotype is referred to as the "Warburg effect" and is associated with an increase in glucose uptake, and a diversion of glycolytic intermediates to alternative pathways that support anabolic processes. These processes include synthesis of nucleic acids, lipids, and proteins, necessary for the rapidly dividing cancer cells, sustaining their growth, proliferation, and capacity for successful metastasis. Triple-negative breast cancer (TNBC) is one of the most aggressive subtypes of breast cancer, with the poorest patient outcome due to its high rate of metastasis. TNBC is characterized by elevated glycolysis and in certain instances, low OXPHOS. This metabolic dysregulation is linked to chemotherapeutic resistance in TNBC research models and patient samples. There is more than a single mechanism by which this metabolic switch occurs and here, we review the current knowledge of relevant molecular mechanisms involved in advanced breast cancer metabolism, focusing on TNBC. These mechanisms include the Warburg effect, glycolytic adaptations, microRNA regulation, mitochondrial involvement, mitochondrial calcium signaling, and a more recent player in metabolic regulation, JAK/STAT signaling. In addition, we explore some of the drugs and compounds targeting cancer metabolic reprogramming. Research on these mechanisms is highly promising and could ultimately offer new opportunities for the development of innovative therapies to treat advanced breast cancer characterized by dysregulated metabolism.

Neopetroside-B alleviates doxorubicin-induced cardiotoxicity via mitochondrial protection

Doxorubicin, a member of the anthracycline family, is a widely prescribed anticancer chemotherapy drug. Unfortunately, cumulative doses of doxorubicin can cause mitochondrial dysfunction, leading to acute or chronic cardiotoxicity. This study demonstrated that Neopetroside-B (NPS-B) protects cardiomyocytes in the presence of doxorubicin. NPS-B improved mitochondrial function in cardiomyocytes by increasing ATP production and oxygen consumption rates. On the other hand, NPS-B negatively influenced cancer cell lines by increasing reactive oxygen species. We analyzed NPS-B-influenced metabolites (VIP > 1.0; AUC>0.7; p < 0.05) and proteins (FC > 2.0) and constructed metabolite-protein enrichment, which showed that NPS-B affected uracil metabolism and NAD-binding proteins (e.g., aldehyde dehydrogenase and glutathione reductase) in cardiomyocytes. However, for the cancer cells, NPS-B decreased the NAD+/NADH balance, impairing cell viability. In a xenograft mouse model treated with doxorubicin, NPS-B reduced cardiac fibrosis and improved cardiac function. NPS-B may be a beneficial intervention to reducing doxorubicin-induced cardiotoxicity with anticancer effects.

Anaphylatoxin C5a receptor signaling induces mitochondrial fusion and sensitizes retinal pigment epithelial cells to oxidative stress

Mitochondrial dynamics is a morphological balance between fragmented and elongated shapes, reflecting mitochondrial metabolic status, cellular damage, and mitochondrial dysfunction. The anaphylatoxin C5a derived from complement component 5 cleavage, enhances cellular responses involved in pathological stimulation, innate immune responses, and host defense. However, the specific response of C5a and its receptor, C5a receptor (C5aR), in mitochondria is unclear. Here, we tested whether the C5a/C5aR signaling axis affects mitochondrial morphology in human-derived retinal pigment epithelial cell monolayers (ARPE-19). C5aR activation with the C5a polypeptide induced mitochondrial elongation. In contrast, oxidatively stressed cells (H2O2) responded to C5a with an enhancement of mitochondrial fragmentation and an increase in the number of pyknotic nuclei. C5a/C5aR signaling increased the expression of mitochondrial fusion-related protein, mitofusin-1 (MFN1) and - 2 (MFN2), as well as enhanced optic atrophy-1 (Opa1) cleavage, which are required for mitochondrial fusion events, whereas the mitochondrial fission protein, dynamin-related protein-1 (Drp1), and mitogen-activated protein kinase (MAPK)-dependent extracellular signal-regulated protein kinase (Erk1/2) phosphorylation were not affected. Moreover, C5aR activation increased the frequency of endoplasmic reticulum (ER)-mitochondria contacts. Finally, oxidative stress induced in a single cell within an RPE monolayer (488 nm blue laser spot stimulation) induced a bystander effect of mitochondrial fragmentation in adjacent surrounding cells only in C5a-treated monolayers. These results suggest that C5a/C5aR signaling produced an intermediate state, characterized by increased mitochondrial fusion and ER-mitochondrial contacts, that sensitizes cells to oxidative stress, leading to mitochondrial fragmentation and cell death.

GSK-3 at the heart of cardiometabolic diseases: Isoform-specific targeting is critical to therapeutic benefit

Glycogen synthase kinase-3 (GSK-3) is a family of serine/threonine kinases. The GSK-3 family has 2 isoforms, GSK-3α and GSK-3β. The GSK-3 isoforms have been shown to play overlapping as well as isoform-specific-unique roles in both, organ homeostasis and the pathogenesis of multiple diseases. In the present review, we will particularly focus on expanding the isoform-specific role of GSK-3 in the pathophysiology of cardiometabolic disorders. We will highlight recent data from our lab that demonstrated the critical role of cardiac fibroblast (CF) GSK-3α in promoting injury-induced myofibroblast transformation, adverse fibrotic remodeling, and deterioration of cardiac function. We will also discuss studies that found the exact opposite role of CF-GSK-3β in cardiac fibrosis. We will review emerging studies with inducible cardiomyocyte (CM)-specific as well as global isoform-specific GSK-3 KOs that demonstrated inhibition of both GSK-3 isoforms provides benefits against obesity-associated cardiometabolic pathologies. The underlying molecular interactions and crosstalk among GSK-3 and other signaling pathways will be discussed. We will briefly review the specificity and limitations of the available small molecule inhibitors targeting GSK-3 and their potential applications to treat metabolic disorders. Finally, we will summarize these findings and offer our perspective on envisioning GSK-3 as a therapeutic target for the management of cardiometabolic diseases.

NOX2 and NOX4 control mitochondrial function in chronic myeloid leukaemia

Cancer cells are characterised by an elevated metabolic plasticity and enhanced production of reactive oxygen species (ROS), two features acknowledged as hallmarks in cancer, with a high translational potential to the therapeutic setting. These aspects, that have been traditionally studied separately, are in fact intimately intermingled. As part of their transforming activity, some oncogenes stimulate rewiring of metabolic processes, whilst simultaneously promoting increased production of intracellular ROS. In this scenario the latest discoveries suggest the relevance of nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOX) to connect ROS production and metabolic control. Here we have analysed the relevance of NOX2 and NOX4 in the regulation of metabolism in chronic myeloid leukaemia (CML), a neoplasia driven by the expression of the breakpoint cluster region-Abelson fusion oncogene (BCR-ABL). Silencing of NOX2 enhances glycolysis and oxidative phosphorylation rates, together with an enhanced production of mitochondrial ROS and a decrease in mitochondrial DNA copy number, which reflects mitochondrial dysfunction. NOX4 expression was upregulated upon NOX2 silencing, and this was required to alter mitochondrial function. Our results support the relevance of NOX2 to regulate metabolism-related signalling pathways downstream of BCR-ABL. Overall we show that NOX2, through the regulation of NOX4 expression, controls metabolism and mitochondrial function in CML cells. This notion was confirmed by transcriptomic analyses, that strongly relate both NOX isoforms with metabolism regulation in CML.

Porcupine Inhibition Disrupts Mitochondrial Function and Homeostasis in WNT Ligand-Addicted Pancreatic Cancer

WNT signaling promotes pancreatic ductal adenocarcinoma (PDAC) through diverse effects on proliferation, differentiation, survival, and stemness. A subset of PDAC with inactivating mutations in ring finger protein 43 (RNF43) show growth dependency on autocrine WNT ligand signaling and are susceptible to agents that block WNT ligand acylation by Porcupine O-acyltransferase, which is required for proper WNT ligand processing and secretion. For this study, global transcriptomic, proteomic, and metabolomic analyses were performed to explore the therapeutic response of RNF43-mutant PDAC to the Porcupine inhibitor (PORCNi) LGK974. LGK974 disrupted cellular bioenergetics and mitochondrial function through actions that included rapid mitochondrial depolarization, reduced mitochondrial content, and inhibition of oxidative phosphorylation and tricarboxylic acid cycle. LGK974 also broadly altered transcriptional activity, downregulating genes involved in cell cycle, nucleotide metabolism, and ribosomal biogenesis and upregulating genes involved in epithelial-mesenchymal transition, hypoxia, endocytosis, and lysosomes. Autophagy and lysosomal activity were augmented in response to LGK974, which synergistically inhibited tumor cell viability in combination with chloroquine. Autocrine WNT ligand signaling dictates metabolic dependencies in RNF43-mutant PDAC through a combination of transcription dependent and independent effects linked to mitochondrial health and function. Metabolic adaptations to mitochondrial damage and bioenergetic stress represent potential targetable liabilities in combination with PORCNi for the treatment of WNT ligand-addicted PDAC.

Pathobiology and Therapeutic Relevance of GSK-3 in Chronic Hematological Malignancies

Glycogen synthase kinase-3 (GSK-3) is an evolutionarily conserved, ubiquitously expressed, multifunctional serine/threonine protein kinase involved in the regulation of a variety of physiological processes. GSK-3 comprises two isoforms (α and β) which were originally discovered in 1980 as enzymes involved in glucose metabolism via inhibitory phosphorylation of glycogen synthase. Differently from other proteins kinases, GSK-3 isoforms are constitutively active in resting cells, and their modulation mainly involves inhibition through upstream regulatory networks. In the early 1990s, GSK-3 isoforms were implicated as key players in cancer cell pathobiology. Active GSK-3 facilitates the destruction of multiple oncogenic proteins which include β-catenin and Master regulator of cell cycle entry and proliferative metabolism (c-Myc). Therefore, GSK-3 was initially considered to be a tumor suppressor. Consistently, GSK-3 is often inactivated in cancer cells through dysregulated upstream signaling pathways. However, over the past 10–15 years, a growing number of studies highlighted that in some cancer settings GSK-3 isoforms inhibit tumor suppressing pathways and therefore act as tumor promoters. In this article, we will discuss the multiple and often enigmatic roles played by GSK-3 isoforms in some chronic hematological malignancies (chronic myelogenous leukemia, chronic lymphocytic leukemia, multiple myeloma, and B-cell non-Hodgkin’s lymphomas) which are among the most common blood cancer cell types. We will also summarize possible novel strategies targeting GSK-3 for innovative therapies of these disorders.

Cancer Metabolism: The Role of Immune Cells Epigenetic Alteration in Tumorigenesis, Progression, and Metastasis of Glioma

Glioma is a type of brain and spinal cord tumor that begins in glial cells that support the nervous system neurons functions. Age, radiation exposure, and family background of glioma constitute are risk factors of glioma initiation. Gliomas are categorized on a scale of four grades according to their growth rate. Grades one and two grow slowly, while grades three and four grow faster. Glioblastoma is a grade four gliomas and the deadliest due to its aggressive nature (accelerated proliferation, invasion, and migration). As such, multiple therapeutic approaches are required to improve treatment outcomes. Recently, studies have implicated the significant roles of immune cells in tumorigenesis and the progression of glioma. The energy demands of gliomas alter their microenvironment quality, thereby inducing heterogeneity and plasticity change of stromal and immune cells via the PI3K/AKT/mTOR pathway, which ultimately results in epigenetic modifications that facilitates tumor growth. PI3K is utilized by many intracellular signaling pathways ensuring the proper functioning of the cell. The activation of PI3K/AKT/mTOR regulates the plasma membrane activities, contributing to the phosphorylation reaction necessary for transcription factors activities and oncogenes hyperactivation. The pleiotropic nature of PI3K/AKT/mTOR makes its activity unpredictable during altered cellular functions. Modification of cancer cell microenvironment affects many cell types, including immune cells that are the frontline cells involved in inflammatory cascades caused by cancer cells via high cytokines synthesis. Typically, the evasion of immunosurveillance by gliomas and their resistance to treatment has been attributed to epigenetic reprogramming of immune cells in the tumor microenvironment, which results from cancer metabolism. Hence, it is speculative that impeding cancer metabolism and/or circumventing the epigenetic alteration of immune cell functions in the tumor microenvironment might enhance treatment outcomes. Herein, from an oncological and immunological perspective, this review discusses the underlying pathomechanism of cell-cell interactions enhancing glioma initiation and metabolism activation and tumor microenvironment changes that affect epigenetic modifications in immune cells. Finally, prospects for therapeutic intervention were highlighted.

Glycogen synthesis and beyond, a comprehensive review of GSK3 as a key regulator of metabolic pathways and a therapeutic target for treating metabolic diseases

Glycogen synthase kinase‐3 (GSK3) is a highly evolutionarily conserved serine/threonine protein kinase first identified as an enzyme that regulates glycogen synthase (GS) in response to insulin stimulation, which involves GSK3 regulation of glucose metabolism and energy homeostasis. Both isoforms of GSK3, GSK3α, and GSK3β, have been implicated in many biological and pathophysiological processes. The various functions of GSK3 are indicated by its widespread distribution in multiple cell types and tissues. The studies of GSK3 activity using animal models and the observed effects of GSK3‐specific inhibitors provide more insights into the roles of GSK3 in regulating energy metabolism and homeostasis. The cross‐talk between GSK3 and some important energy regulators and sensors and the regulation of GSK3 in mitochondrial activity and component function further highlight the molecular mechanisms in which GSK3 is involved to regulate the metabolic activity, beyond its classical regulatory effect on GS. In this review, we summarize the specific roles of GSK3 in energy metabolism regulation in tissues that are tightly associated with energy metabolism and the functions of GSK3 in the development of metabolic disorders. We also address the impacts of GSK3 on the regulation of mitochondrial function, activity and associated metabolic regulation. The application of GSK3 inhibitors in clinical tests will be highlighted too. Interactions between GSK3 and important energy regulators and GSK3‐mediated responses to different stresses that are related to metabolism are described to provide a brief overview of previously less‐appreciated biological functions of GSK3 in energy metabolism and associated diseases through its regulation of GS and other functions.

Cardiomyocyte-produced miR-339-5p mediates pathology in Duchenne muscular dystrophy cardiomyopathy

Duchenne muscular dystrophy (DMD) is an X-linked genetic disease characterized by severe, progressive muscle wasting. Cardiomyopathy has emerged as a leading cause of death in patients with DMD. The mechanisms contributing to DMD cardiac disease remain under investigation and specific therapies available are lacking. Our prior work has shown that DMD-iPSC derived cardiomyocytes (DMD-iCMs) are vulnerable to oxidative stress injury and chronic exposure to DMD secreted exosomes impaired the cell's ability to protect against stress. In this study, we sought to examine a mechanism by which DMD cardiac exosomes impair cellular response through altering important stress-responsive genes in the recipient cells. Here, we report that DMD-iCMs secrete exosomes containing altered microRNA (miR) profiles in comparison to healthy controls. In particular, miR-339-5p was upregulated in DMD-iCMs, DMD exosomes, and in mdx mouse cardiac tissue. Restoring dystrophin in DMD-iCMs improved the cellular response to stress and was associated with downregulation of miR-339-5p, suggesting that it is disease-specific. Knockdown of miR-339-5p was associated with increased expression of MDM2, GSK3A and MAP2K3, which are genes involved in important stress-responsive signaling pathways. Finally, knockdown of miR-339-5p led to mitochondrial protection and a reduction in cell death in DMD-iCMs, indicating miR-339-5p is involved in direct modulation of stress-responsiveness. Together, these findings identify a potential mechanism by which exosomal miR-339-5p may be modulating cell signaling pathways which are important for robust stress responses. Additionally, these exosomal miRs may provide important disease specific targets for future therapeutic advancements for the management and diagnosis of DMD cardiomyopathy.

GSK-3: a multifaceted player in acute leukemias

Glycogen synthase kinase 3 (GSK-3) consists of two isoforms (α and β) that were originally linked to glucose metabolism regulation. However, GSK-3 is also involved in several signaling pathways controlling many different key functions in healthy cells. GSK-3 is a unique kinase in that its isoforms are constitutively active, while they are inactivated mainly through phosphorylation at Ser residues by a variety of upstream kinases. In the early 1990s, GSK-3 emerged as a key player in cancer cell pathophysiology. Since active GSK-3 promotes destruction of multiple oncogenic proteins (e.g., β-catenin, c-Myc, Mcl-1) it was considered to be a tumor suppressor. Accordingly, GSK-3 is frequently inactivated in human cancer via aberrant regulation of upstream signaling pathways. More recently, however, it has emerged that GSK-3 isoforms display also oncogenic properties, as they up-regulate pathways critical for neoplastic cell proliferation, survival, and drug-resistance. The regulatory roles of GSK-3 isoforms in cell cycle, apoptosis, DNA repair, tumor metabolism, invasion, and metastasis reflect the therapeutic relevance of these kinases and provide the rationale for combining GSK-3 inhibitors with other targeted drugs. Here, we discuss the multiple and often conflicting roles of GSK-3 isoforms in acute leukemias. We also review the current status of GSK-3 inhibitor development for innovative leukemia therapy.

Hexokinase 2 in Cancer: A Prima Donna Playing Multiple Characters

Hexokinases are a family of ubiquitous exose-phosphorylating enzymes that prime glucose for intracellular utilization. Hexokinase 2 (HK2) is the most active isozyme of the family, mainly expressed in insulin-sensitive tissues. HK2 induction in most neoplastic cells contributes to their metabolic rewiring towards aerobic glycolysis, and its genetic ablation inhibits malignant growth in mouse models. HK2 can dock to mitochondria, where it performs additional functions in autophagy regulation and cell death inhibition that are independent of its enzymatic activity. The recent definition of HK2 localization to contact points between mitochondria and endoplasmic reticulum called Mitochondria Associated Membranes (MAMs) has unveiled a novel HK2 role in regulating intracellular Ca²⁺ fluxes. Here, we propose that HK2 localization in MAMs of tumor cells is key in sustaining neoplastic progression, as it acts as an intersection node between metabolic and survival pathways. Disrupting these functions by targeting HK2 subcellular localization can constitute a promising anti-tumor strategy.

GSK-3β Can Regulate the Sensitivity of MIA-PaCa-2 Pancreatic and MCF-7 Breast Cancer Cells to Chemotherapeutic Drugs, Targeted Therapeutics and Nutraceuticals

Glycogen synthase kinase-3 (GSK-3) is a regulator of signaling pathways. KRas is frequently mutated in pancreatic cancers. The growth of certain pancreatic cancers is KRas-dependent and can be suppressed by GSK-3 inhibitors, documenting a link between KRas and GSK-3. To further elucidate the roles of GSK-3β in drug-resistance, we transfected KRas-dependent MIA-PaCa-2 pancreatic cells with wild-type (WT) and kinase-dead (KD) forms of GSK-3β. Transfection of MIA-PaCa-2 cells with WT-GSK-3β increased their resistance to various chemotherapeutic drugs and certain small molecule inhibitors. Transfection of cells with KD-GSK-3β often increased therapeutic sensitivity. An exception was observed with cells transfected with WT-GSK-3β and sensitivity to the BCL2/BCLXL ABT737 inhibitor. WT-GSK-3β reduced glycolytic capacity of the cells but did not affect the basal glycolysis and mitochondrial respiration. KD-GSK-3β decreased both basal glycolysis and glycolytic capacity and reduced mitochondrial respiration in MIA-PaCa-2 cells. As a comparison, the effects of GSK-3 on MCF-7 breast cancer cells, which have mutant PIK3CA, were examined. KD-GSK-3β increased the resistance of MCF-7 cells to chemotherapeutic drugs and certain signal transduction inhibitors. Thus, altering the levels of GSK-3β can have dramatic effects on sensitivity to drugs and signal transduction inhibitors which may be influenced by the background of the tumor.

Glycogen synthase kinase 3β in tumorigenesis and oncotherapy (Review)

Glycogen synthase kinase 3β (GSK 3β), a multifunctional serine and threonine kinase, plays a critical role in a variety of cellular activities, including signaling transduction, protein and glycogen metabolism, cell proliferation, cell differentiation, and apoptosis. Therefore, aberrant regulation of GSK 3β results in a broad range of human diseases, such as tumors, diabetes, inflammation and neurodegenerative diseases. Accumulating evidence has suggested that GSK 3β is correlated with tumorigenesis and progression. However, GSK 3β is controversial due to its bifacial roles of tumor suppression and activation. In addition, overexpression of GSK 3β is involved in tumor growth, whereas it contributes to the cell sensitivity to chemotherapy. However, the underlying regulatory mechanisms of GSK 3β in tumorigenesis remain obscure and require further in‑depth investigation. In this review, we comprehensively summarize the roles of GSK 3β in tumorigenesis and oncotherapy, and focus on its potentials as an available target in oncotherapy.

Ruthenacarborane-Phenanthroline Derivatives as Potential Metallodrugs

Ruthenium-based complexes have received much interest as potential metallodrugs. In this work, four Ru^II complexes bearing a dicarbollide moiety, a carbonyl ligand, and a phenanthroline-based ligand were synthesized and characterized, including single crystal diffraction analysis of compounds 2, 4, and 5 and an observed side product SP1. Complexes 2-5 are air and moisture stable under ambient conditions. They show excellent solubility in organic solvents, but low solubility in water.

Akt-ing Up Just About Everywhere: Compartment-Specific Akt Activation and Function in Receptor Tyrosine Kinase Signaling

The serine/threonine kinase Akt is a master regulator of many diverse cellular functions, including survival, growth, metabolism, migration, and differentiation. Receptor tyrosine kinases are critical regulators of Akt, as a result of activation of phosphatidylinositol-3-kinase (PI3K) signaling leading to Akt activation upon receptor stimulation. The signaling axis formed by receptor tyrosine kinases, PI3K and Akt, as well as the vast range of downstream substrates is thus central to control of cell physiology in many different contexts and tissues. This axis must be tightly regulated, as disruption of PI3K-Akt signaling underlies the pathology of many diseases such as cancer and diabetes. This sophisticated regulation of PI3K-Akt signaling is due in part to the spatial and temporal compartmentalization of Akt activation and function, including in specific nanoscale domains of the plasma membrane as well as in specific intracellular membrane compartments. Here, we review the evidence for localized activation of PI3K-Akt signaling by receptor tyrosine kinases in various specific cellular compartments, as well as that of compartment-specific functions of Akt leading to control of several fundamental cellular processes. This spatial and temporal control of Akt activation and function occurs by a large number of parallel molecular mechanisms that are central to regulation of cell physiology.

Acetaminophen hepatotoxicity: A mitochondrial perspective

Acetaminophen (APAP) is a highly effective analgesic, which is safe at therapeutic doses. However, an overdose can cause hepatotoxicity and even liver failure. APAP toxicity is currently the most common cause of acute liver failure in the United States. Decades of research on mechanisms of liver injury have established the role of mitochondria as central players in APAP-induced hepatocyte necrosis and this chapter examines the various facets of the organelle's involvement in the process of injury as well as in resolution of damage. The injury process is initiated by formation of a reactive metabolite, which binds to sulfhydryl groups of cellular proteins including mitochondrial proteins. This inhibits the electron transport chain and leads to formation of reactive oxygen species, which induce the activation of redox-sensitive members of the MAP kinase family ultimately causing activation of c-Jun N terminal kinase, JNK. Translocation of JNK to the mitochondria then amplifies mitochondrial dysfunction, ultimately resulting in mitochondrial permeability transition and release of mitochondrial intermembrane proteins, which trigger nuclear DNA fragmentation. Together, these events result in hepatocyte necrosis, while adaptive mechanisms such as mitophagy remove damaged mitochondria and minimize the extent of the injury. This oscillation between recovery and necrosis is predominant in cells at the edge of the necrotic area in the liver, where induction of mitochondrial biogenesis is important for liver regeneration. All these aspects of mitochondria in APAP hepatotoxicity, as well as their relevance to humans with APAP overdose and development of therapeutic approaches will be examined in detail in this chapter.

[ADAM17 knockdown increases sensitivity of SW480 cells to cetuximad]

OBJECTIVE

To explore the association between expression of ADAM17 and cetuximad resistance in human colorectal cancer SW480 cells.

METHODS

The expression of ADAM17 was detected using Western blotting in different human colorectal cancer cell lines, and the cells highly expressing ADAM17 were selected as the target cells. SW480 cells were transfected with ADAM17-siRNA 1 and ADAM17-siRNA 2 and the changes in the expression of ADAM17 protein were detected using Western blotting. SW480 cells were exposed to cetuximad for 24 h and the cell apoptosis was analyzed using flow cytometry. Transwell assay was used to examine the migration ability of SW480 cells with different expression levels of ADAM17; Western blotting was used to analyze the changes in the expressions of AKT signaling pathway-related proteins in the treated cells.

RESULTS

The baseline expressions of ADAM17 were significantly higher in SW480 cells than in the other human colorectal cancer cell lines tested (P &lt; 0.05). Both ADAM17-siRNA 1 and 2 effectively reduced the expression of ADAM17 protein in SW480 cells. Knockdown of ADAM17 with siRNA 1 significantly increased the sensitivity of SW480 cells to tocetuximad (P &lt; 0.05), obviously inhibited the cell proliferation, migration and invasion, and significantly reduced the expressions of p-EGFR and p-AKT in the cells (P &lt; 0.001).

CONCLUSIONS

ADAM17 knockdown obviously inhibits EGFR-AKT signaling pathway and increases the sensitivity of SW480 cells to tocetuximad.

Metabolic Plasticity of Tumor Cell Mitochondria

Mitochondria are dynamic organelles that exchange a multiplicity of signals with other cell compartments, in order to finely adjust key biological routines to the fluctuating metabolic needs of the cell. During neoplastic transformation, cells must provide an adequate supply of the anabolic building blocks required to meet a relentless proliferation pressure. This can occur in conditions of inconstant blood perfusion leading to variations in oxygen and nutrient levels. Mitochondria afford the bioenergetic plasticity that allows tumor cells to adapt and thrive in this ever changing and often unfavorable environment. Here we analyse how mitochondria orchestrate the profound metabolic rewiring required for neoplastic growth.

Targeting Mitochondrial Ion Channels to Fight Cancer

In recent years, several experimental evidences have underlined a new role of ion channels in cancer development and progression. In particular, mitochondrial ion channels are arising as new oncological targets, since it has been proved that most of them show an altered expression during tumor development and the pharmacological targeting of some of them have been demonstrated to be able to modulate cancer growth and progression, both in vitro as well as in vivo in pre-clinical mouse models. In this scenario, pharmacology of mitochondrial ion channels would be in the near future a new frontier for the treatment of tumors. In this review, we discuss the new advances in the field, by focusing our attention on the improvements in new drug developments to target mitochondrial ion channels.

Blockage of endoplasmic reticulum stress attenuates nilotinib-induced cardiotoxicity by inhibition of the Akt-GSK3β-Nox4 signaling

Cardiotoxicity is a critical side-effect of nilotinib during treatment for cancer, such as chronic myeloid leukemia, while the potential signaling mechanisms remain unclear. The role of and the relationship between endoplasmic reticulum (ER) stress and mitochondrial dysfunction was investigated in nilotinib-induced cardiac H9C2 injury as a suitable cell model. Our results showed that ER stress was persistently induced in nilotinib-treated cells, evidenced by increase of GRP78, CHOP, ATF4 and XBP1 as well as phospho-PERK^Thr980. The results from 4-phenylbutyrate (PBA, an ER stress inhibitor) and SC79 (a specific Akt activator) suggested that ER stress increased activity of glycogen synthase kinase-3 beta (GSK3β) that is reflected by decrease of phospho-GSK3β^Ser9, through downregulation of phospho-Akt^Ser473, and that prolonged ER stress and activated GSK3β involved nilotinib-induced apoptosis. In addition, the data from JNK inhibition using SP600125 showed that over-activated JNK was responsible for Akt de-phosphorylation. Moreover, the abundance of NADPH oxidase (Nox4) was significantly increased following nilotinib treatment, which was prevented by SB216763 (a specific GSK3β inhibitor). Additionally, mitochondrial dysfunction was indicated by reduced mitochondrial membrane potential (MMP) level and increased reactive oxygen species level. In nilotinib-treated cells, knockdown of Nox4 preserved MMP level, abrogated reactive oxygen species production, and decreased apoptosis. Accordingly, our data demonstrated that inhibition of ER stress may protect cardiomyocytes against nilotinib toxicity potentially through inactivation of Akt-GSK3β-Nox4 signaling. These findings may provide an attractive therapeutic target for treatment of nilotinib-related cardiotoxicity.

Towards a Unified Understanding of Lithium Action in Basic Biology and its Significance for Applied Biology

Lithium has literally been everywhere forever, since it is one of the three elements created in the Big Bang. Lithium concentration in rocks, soil, and fresh water is highly variable from place to place, and has varied widely in specific regions over evolutionary and geologic time. The biological effects of lithium are many and varied. Based on experiments in which animals are deprived of lithium, lithium is an essential nutrient. At the other extreme, at lithium ingestion sufficient to raise blood concentration significantly over 1 mM/, lithium is acutely toxic. There is no consensus regarding optimum levels of lithium intake for populations or individuals-with the single exception that lithium is a generally accepted first-line therapy for bipolar disorder, and specific dosage guidelines for sufferers of that condition are generally agreed on. Epidemiological evidence correlating various markers of social dysfunction and disease vs. lithium level in drinking water suggest benefits of moderately elevated lithium compared to average levels of lithium intake. In contrast to other biologically significant ions, lithium is unusual in not having its concentration in fluids of multicellular animals closely regulated. For hydrogen ions, sodium ions, potassium ions, calcium ions, chloride ions, and magnesium ions, blood and extracellular fluid concentrations are closely and necessarily regulated by systems of highly selective channels, and primary and secondary active transporters. Lithium, while having strong biological activity, is tolerated over body fluid concentrations ranging over many orders of magnitude. The lack of biological regulation of lithium appears due to lack of lithium-specific binding sites and selectivity filters. Rather lithium exerts its myriad physiological and biochemical effects by competing for macromolecular sites that are relatively specific for other cations, most especially for sodium and magnesium. This review will consider what is known about the nature of this competition and suggest using and extending this knowledge towards the goal of a unified understanding of lithium in biology and the application of that understanding in medicine and nutrition.

EGb761 Ameliorates Neuronal Apoptosis and Promotes Angiogenesis in Experimental Intracerebral Hemorrhage via RSK1/GSK3β Pathway

Neuronal apoptosis after intracerebral hemorrhage (ICH) plays an essential role in neurological deterioration. Preclinical studies have shown that EGb761, an extract of Ginkgo biloba, is neuroprotective in some other neurological diseases with apoptosis. This study was conducted to investigate the potential neuroprotective effect of EGb761 on neuronal apoptosis in experimental ICH. A model of ICH was induced in C57BL/6 mice by injecting collagenase. EGb761 was administered for 21 days and neurologic behaviors were assessed at 1, 3, 7, 14, and 21 days after ICH. RNAi-mediated knockdown of p90 ribosomal S6 kinase 1 (RSK1) was used to further investigate the role of RSK1 in EGb761-induced neuroprotective effects. Neuronal death was determined by TUNEL staining. The image datasets of neurovascular networks were acquired via micro-optical sectioning tomography (MOST). The glycogen synthase kinase-3β (GSK3β) activity was assayed using commercial kit. Primary cultured cortical neurons were exposed to ferrous iron and treated with EGb761. Apoptotic neurons were counted by flow cytometry. RSK1, GSK3β, phosphorylated-GSK3β (pGSK3β), Bcl2, Bax, cleaved-caspase3 (CC3), and VEGF were measured by Western blot. The pGSK3β was also detected by immunofluorescence staining. We found that mice in EGb761 group performed better on rotarod test. Reduced TUNEL-positive neurons and richer microvascular networks were observed in mice treated with EGb761. EGb761 attenuates neuronal apoptosis induced by ferrous iron counted by flow cytometry in vitro. Decreased GSK3β activity was observed in EGb761-treated mice compared with mice with ICH. EGb761 increased the expression of pGSK3β (Ser9), RSK1 and the Bcl2/Bax ratio, and VEGF and decreased CC3 expression. In conclusion, EGb761 reduces neuronal apoptosis and promotes angiogenesis in experimental intracerebral hemorrhage via RSK1/GSK3β pathway.

Wnt Signaling Prevents the Aβ Oligomer-Induced Mitochondrial Permeability Transition Pore Opening Preserving Mitochondrial Structure in Hippocampal Neurons

Alzheimer's disease (AD) is a neurodegenerative disorder mainly known for synaptic impairment and neuronal cell loss, affecting memory processes. Beside these damages, mitochondria have been implicated in the pathogenesis of AD through the induction of the mitochondrial permeability transition pore (mPTP). The mPTP is a non-selective pore that is formed under apoptotic conditions, disturbing mitochondrial structure and thus, neuronal viability. In AD, Aβ oligomers (Aβos) favor the opening of the pore, activating mitochondria-dependent neuronal cell death cascades. The Wnt signaling activated through the ligand Wnt3a has been described as a neuroprotective signaling pathway against amyloid-β (Aβ) peptide toxicity in AD. However, the mechanisms by which Wnt signaling prevents Aβos-induced neuronal cell death are unclear. We proposed here to study whether Wnt signaling protects neurons earlier than the late damages in the progression of the disease, through the preservation of the mitochondrial structure by the mPTP inhibition. To study specific events related to mitochondrial permeabilization we performed live-cell imaging from primary rat hippocampal neurons, and electron microscopy to analyze the mitochondrial morphology and structure. We report here that Wnt3a prevents an Aβos-induced cascade of mitochondrial events that leads to neuronal cell death. This cascade involves (a) mPTP opening, (b) mitochondrial swelling, (c) mitochondrial membrane potential loss and (d) cytochrome c release, thus leading to neuronal cell death. Furthermore, our results suggest that the activation of the Wnt signaling prevents mPTP opening by two possible mechanisms, which involve the inhibition of mitochondrial GSK-3β and/or the modulation of mitochondrial hexokinase II levels and activity. This study suggests a possible new approach for the treatment of AD from a mitochondrial perspective, and will also open new lines of study in the field of Wnt signaling in neuroprotection.

Impact of intracellular ion channels on cancer development and progression

Cancer research is nowadays focused on the identification of possible new targets in order to try to develop new drugs for curing untreatable tumors. Ion channels have emerged as "oncogenic" proteins, since they have an aberrant expression in cancers compared to normal tissues and contribute to several hallmarks of cancer, such as metabolic re-programming, limitless proliferative potential, apoptosis-resistance, stimulation of neo-angiogenesis as well as cell migration and invasiveness. In recent years, not only the plasma membrane but also intracellular channels and transporters have arisen as oncological targets and were proposed to be associated with tumorigenesis. Therefore, the research is currently focusing on understanding the possible role of intracellular ion channels in cancer development and progression on one hand and, on the other, on developing new possible drugs able to modulate the expression and/or activity of these channels. In a few cases, the efficacy of channel-targeting drugs in reducing tumors has already been demonstrated in vivo in preclinical mouse models.

Mg(++) requirement for MtHK binding, and Mg(++) stabilization of mitochondrial membranes via activation of MtHK & MtCK and promotion of mitochondrial permeability transition pore closure: A hypothesis on mechanisms underlying Mg(++)'s antioxidant and cytoprotective effects

Evidence points to magnesium's antioxidant, anti-necrotic, and anti-apoptotic effects in cardio- and neuroprotection. With magnesium being involved in over 300 biochemical reactions, the mechanisms underlying its cytoprotective and antioxidant effects have remained elusive. The profound anti-apoptotic, anabolic, and antioxidant effects of mitochondrion bound hexokinase (MtHk), and the anti-apoptotic, anti-necrotic, and antioxidant functions of mitochondrial creatine kinase (MtCK) have been established over the past few decades. As powerful regulators of the mitochondrial permeability transition pore (PTP), MtHK and MtCK promote anti-apoptosis and anti-necrosis by stabilizing mitochondrial outer and inner membranes. In this article, it is proposed that magnesium is essentially and directly involved in mitochondrial membrane stabilization via (i) Mg(++) ion requirement for the binding of mitochondrial hexokinase (ii) Mg(++)'s allosteric activation of mitochondrial bound hexokinase, and stimulation of mitochondrial bound creatine kinase activities, and (iii) Mg(++) inhibition of PTP opening by Ca(++) ions. These effects of Mg(++) ions are indirectly supplanted by the stimulatory effect of magnesium on the Akt kinase survival pathway. The "Magnesium/Calcium Yin Yang Hypothesis" proposes here that because of the antagonistic effects of Ca(++) and Mg(++) ions in the presence of high Ca(++) ion concentration at MtHK, MtCK, and PTP, magnesium supplementation may provide cytoprotective effects in the treatment of some degenerative diseases and cytopathies with high intracellular [Ca(++)]/ [Mg(++)] ratio at these sites, whether of genetic, developmental, drug induced, ischemic, immune based, toxic, or infectious etiology.

SIRT3 Blocks Aging-Associated Tissue Fibrosis in Mice by Deacetylating and Activating Glycogen Synthase Kinase 3β

Tissue fibrosis is a major cause of organ dysfunction during chronic diseases and aging. A critical step in this process is transforming growth factor β1 (TGF-β1)-mediated transformation of fibroblasts into myofibroblasts, cells capable of synthesizing extracellular matrix. Here, we show that SIRT3 controls transformation of fibroblasts into myofibroblasts via suppressing the profibrotic TGF-β1 signaling. We found that Sirt3 knockout (KO) mice with age develop tissue fibrosis of multiple organs, including heart, liver, kidney, and lungs but not whole-body SIRT3-overexpressing mice. SIRT3 deficiency caused induction of TGF-β1 expression and hyperacetylation of glycogen synthase kinase 3β (GSK3β) at residue K15, which negatively regulated GSK3β activity to phosphorylate the substrates Smad3 and β-catenin. Reduced phosphorylation led to stabilization and activation of these transcription factors regulating expression of the profibrotic genes. SIRT3 deacetylated and activated GSK3β and thereby blocked TGF-β1 signaling and tissue fibrosis. These data reveal a new role of SIRT3 to negatively regulate aging-associated tissue fibrosis and discloses a novel phosphorylation-independent mechanism controlling the catalytic activity of GSK3β.

The Mitochondrial Permeability Transition Pore: Channel Formation by F-ATP Synthase, Integration in Signal Transduction, and Role in Pathophysiology

The mitochondrial permeability transition (PT) is a permeability increase of the inner mitochondrial membrane mediated by a channel, the permeability transition pore (PTP). After a brief historical introduction, we cover the key regulatory features of the PTP and provide a critical assessment of putative protein components that have been tested by genetic analysis. The discovery that under conditions of oxidative stress the F-ATP synthases of mammals, yeast, and Drosophila can be turned into Ca(2+)-dependent channels, whose electrophysiological properties match those of the corresponding PTPs, opens new perspectives to the field. We discuss structural and functional features of F-ATP synthases that may provide clues to its transition from an energy-conserving into an energy-dissipating device as well as recent advances on signal transduction to the PTP and on its role in cellular pathophysiology.

Role of Opioid Receptors Signaling in Remote Electrostimulation--Induced Protection against Ischemia/Reperfusion Injury in Rat Hearts

Aims

Our previous studies demonstrated that remote electro-stimulation (RES) increased myocardial GSK3 phosphorylation and attenuated ischemia/ reperfusion (I/R) injury in rat hearts. However, the role of various opioid receptors (OR) subtypes in preconditioned RES-induced myocardial protection remains unknown. We investigated the role of OR subtype signaling in RES-induced cardioprotection against I/R injury of the rat heart.

Methods & Results

Male Spraque-Dawley rats were used. RES was performed on median nerves area with/without pretreatment with various receptors antagonists such as opioid receptor (OR) subtype receptors (KOR, DOR, and MOR). The expressions of Akt, GSK3, and PKCε expression were analyzed by Western blotting. When RES was preconditioned before the I/R model, the rat's hemodynamic index, infarction size, mortality and serum CK-MB were evaluated. Our results showed that Akt, GSK3 and PKCε expression levels were significantly increased in the RES group compared to the sham group, which were blocked by pretreatment with specific antagonists targeting KOR and DOR, but not MOR subtype. Using the I/R model, the duration of arrhythmia and infarct size were both significantly attenuated in RES group. The mortality rates of the sham RES group, the RES group, RES group + KOR antagonist, RES group + DOR/MOR antagonists (KOR left), RES group + DOR antagonist, and RES group + KOR/MOR antagonists (DOR left) were 50%, 20%, 67%, 13%, 50% and 55%, respectively.

Conclusion

The mechanism of RES-induced myocardial protection against I/R injury seems to involve multiple target pathways such as Akt, KOR and/or DOR signaling.

SIRT3 Is Crucial for Maintaining Skeletal Muscle Insulin Action and Protects Against Severe Insulin Resistance in High-Fat-Fed Mice

Protein hyperacetylation is associated with glucose intolerance and insulin resistance, suggesting that the enzymes regulating the acetylome play a role in this pathological process. Sirtuin 3 (SIRT3), the primary mitochondrial deacetylase, has been linked to energy homeostasis. Thus, it is hypothesized that the dysregulation of the mitochondrial acetylation state, via genetic deletion of SIRT3, will amplify the deleterious effects of a high-fat diet (HFD). Hyperinsulinemic-euglycemic clamp experiments show, for the first time, that mice lacking SIRT3 exhibit increased insulin resistance due to defects in skeletal muscle glucose uptake. Permeabilized muscle fibers from HFD-fed SIRT3 knockout (KO) mice showed that tricarboxylic acid cycle substrate-based respiration is decreased while fatty acid-based respiration is increased, reflecting a fuel switch from glucose to fatty acids. Consistent with reduced muscle glucose uptake, hexokinase II (HKII) binding to the mitochondria is decreased in muscle from HFD-fed SIRT3 KO mice, suggesting decreased HKII activity. These results show that the absence of SIRT3 in HFD-fed mice causes profound impairments in insulin-stimulated muscle glucose uptake, creating an increased reliance on fatty acids. Insulin action was not impaired in the lean SIRT3 KO mice. This suggests that SIRT3 protects against dietary insulin resistance by facilitating glucose disposal and mitochondrial function.

Reprint of "The mitochondrial permeability transition pore and its adaptive responses in tumor cells"

This review covers recent progress on the nature of the mitochondrial permeability transition pore (PTP) – a key effector in the mitochondrial pathways to cell death – and on the adaptive responses of tumor cells that desensitize the PTP to Ca(2+) and reactive oxygen species (ROS), thereby playing an important role in the resistance of tumors to cell death. The discovery that the PTP forms from dimers of F-ATP synthase; and the definition of the Ca(2+)- and ROS-dependent signaling pathways affecting the transition of the F-ATP synthase from an energy-conserving to an energy-dissipating device open new perspectives for therapeutic intervention in cancer cells.

AZD5363 Inhibits Inflammatory Synergy between Interleukin-17 and Insulin/Insulin-Like Growth Factor 1

In the United States, one-third of population is affected by obesity and almost 29 million people are suffering from type 2 diabetes. Obese people have elevated serum levels of insulin, insulin-like growth factor 1 (IGF1), and interleukin-17 (IL-17). Insulin and IGF1 are known to enhance IL-17-induced expression of inflammatory cytokines and chemokines, which may contribute to the chronic inflammatory status observed in obese people. We have previously demonstrated that insulin/IGF1 signaling pathway crosstalks with IL-17-activated nuclear factor-κB pathway through inhibiting glycogen synthase kinase 3β (GSK3β) activity. However, it is unclear whether GSK3α also plays a role and whether this crosstalk can be manipulated by AZD5363, a novel pan-Akt inhibitor that has been shown to increase glycogen synthase kinase 3 activity through reducing phosphorylation of GSK3α and GSK3β. In this study, we investigated IL-17-induced expression of C-X-C motif ligand 1 (Cxcl1), C-C motif ligand 20 (Ccl20), and interleukin-6 (Il-6) in wild-type, GSK3α^−/−, and GSK3β^−/− mouse embryonic fibroblast cells as well as in mouse prostate tissues by real-time quantitative PCR. We examined the proteins involved in the signaling pathways by Western blot analysis. We found that insulin and IGF1 enhanced IL-17-induced expression of Cxcl1, Ccl20, and Il-6, which was associated with increased phosphorylation of GSK3α and GSK3β in the presence of insulin and IGF1. AZD5363 inhibited the synergy between IL-17 and insulin/IGF1 through reducing phosphorylation of GSK3α and GSK3β by inhibiting Akt function. These findings imply that the cooperative crosstalk of IL-17 and insulin/IGF1 in initiating inflammatory responses may be alleviated by AZD5363.

The mitochondrial permeability transition pore and its adaptive responses in tumor cells

This review covers recent progress on the nature of the mitochondrial permeability transition pore (PTP) - a key effector in the mitochondrial pathways to cell death - and on the adaptive responses of tumor cells that desensitize the PTP to Ca(2+) and reactive oxygen species (ROS), thereby playing an important role in the resistance of tumors to cell death. The discovery that the PTP forms from dimers of F-ATP synthase; and the definition of the Ca(2+)- and ROS-dependent signaling pathways affecting the transition of the F-ATP synthase from an energy-conserving to an energy-dissipating device open new perspectives for therapeutic intervention in cancer cells.

The mitochondrial permeability transition pore and cancer: molecular mechanisms involved in cell death

Since its discovery in the 1970s, the mitochondrial permeability transition (MPT) has been proposed to be a strategic regulator of cell death. Intense research efforts have focused on elucidating the molecular components of the MPT because this knowledge may help to better understand and treat various pathologies ranging from neurodegenerative and cardiac diseases to cancer. In the case of cancer, several studies have revealed alterations in the activity of the mitochondrial permeability transition pore (mPTP) and have determined its regulatory mechanism; these studies have also suggested that suppression of the activity of the mPTP, rather than its inactivation, commonly occurs in solid neoplasms. This review focuses on the most recent advances in understanding mPTP regulation in cancer and highlights the ability of the mPTP to impede the mechanisms of cell death.

Mitochondrial channels: ion fluxes and more

The field of mitochondrial ion channels has recently seen substantial progress, including the molecular identification of some of the channels. An integrative approach using genetics, electrophysiology, pharmacology, and cell biology to clarify the roles of these channels has thus become possible. It is by now clear that many of these channels are important for energy supply by the mitochondria and have a major impact on the fate of the entire cell as well. The purpose of this review is to provide an up-to-date overview of the electrophysiological properties, molecular identity, and pathophysiological functions of the mitochondrial ion channels studied so far and to highlight possible therapeutic perspectives based on current information.

Spautin-1, a novel autophagy inhibitor, enhances imatinib-induced apoptosis in chronic myeloid leukemia

Imatinib mesylate (IM), a targeted competitive inhibitor of the BCR-ABL tyrosine kinase, has revolutionized the clinical treatment of chronic myeloid leukemia (CML). However, resistance and intolerance are still a challenge in the treatment of CML. Autophagy has been proposed to play a role in IM resistance. To investigate the anti-leukemic activity of specific and potent autophagy inhibitor-1 (spautin-1) in CML, we detected its synergistic effect with IM in K562 and CML cells. Our results showed that spautin-1 markedly inhibited IM-induced autophagy in CML cells by downregulating Beclin-1. Spautin-1 enhanced IM-induced CML cell apoptosis by reducing the expression of the anti-apoptotic proteins Mcl-1 and Bcl-2. We further demonstrated that the proapoptotic activity of spautin-1 was associated with activation of GSK3β, an important downstream effector of PI3K/AKT. The findings indicate that the autophagy inhibitor spautin-1 enhances IM-induced apoptosis by inactivating PI3K/AKT and activating downstream GSK3β, leading to downregulation of Mcl-1 and Bcl-2, which represents a promising approach to improve the efficacy of IM in the treatment of patients with CML.

The role of mitochondria in the oncogenic signal transduction

Mitochondria are intracellular organelles thought to have evolved from an alphaproteobacterium engulfed by the ancestor of the eukaryotic cell, an archeon, two billion years ago. Although mitochondria are frequently recognised as the "power plant" of the cell, the function of these organelles go beyond the simple generation of ATP. In fact, mounting evidence suggests that mitochondria are involved in several cellular processes, from regulation of cell death to signal transduction. Given this important role in cell physiology, mitochondrial dysfunction has been frequently associated with human diseases including cancer. Importantly, recent evidence suggests that mitochondrial function is directly regulated by oncogenes and tumour suppressors. However, the consequences of deregulation of mitochondrial function in tumour formation are still unclear. In this review, I propose that mitochondria play a pivotal role in shaping the oncogenic signalling cascade and that mitochondrial dysfunction, in some circumstances, is a required step for cancer transformation.

Proliferation and survival signaling from both Jak2-V617F and Lyn involving GSK3 and mTOR/p70S6K/4EBP1 in PVTL-1 cell line newly established from acute myeloid leukemia transformed from polycythemia vera

The gain of function mutation JAK2-V617F is very frequently found in myeloproliferative neoplasms (MPNs) and is strongly implicated in pathogenesis of these and other hematological malignancies. Here we report establishment of a new leukemia cell line, PVTL-1, homozygous for JAK2-V617F from a 73-year-old female patient with acute myeloid leukemia (AML) transformed from MPN. PVTL-1 is positive for CD7, CD13, CD33, CD34, CD117, HLA-DR, and MPO, and has complex karyotypic abnormalities, 44,XX,-5q,-7,-8,add(11)(p11.2),add(11)(q23),−16,+21,−22,+mar1. Sequence analysis of JAK2 revealed only the mutated allele coding for Jak2-V617F. Proliferation of PVTL-1 was inhibited and apoptosis was induced by the pan-Jak inhibitor Jak inhibitor-1 (JakI-1) or dasatinib, which inhibits the Src family kinases as well as BCR/ABL. Consistently, the Src family kinase Lyn was constitutively activated with phosphorylation of Y396 in the activation loop, which was inhibited by dasatinib but not by JakI-1. Further analyses with JakI-1 and dasatinib indicated that Jak2-V617F phosphorylated STAT5 and SHP2 while Lyn phosphorylated SHP1, SHP2, Gab-2, c-Cbl, and CrkL to induce the SHP2/Gab2 and c-Cbl/CrkL complex formation. In addition, JakI-1 and dasatinib inactivated the mTOR/p70S6K/4EBP1 pathway and reduced the inhibitory phosphorylation of GSK3 in PVTL-1 cells, which correlated with their effects on proliferation and survival of these cells. Furthermore, inhibition of GSK3 by its inhibitor SB216763 mitigated apoptosis induced by dasatinib but not by JakI-1. Together, these data suggest that apoptosis may be suppressed in PVTL-1 cells through inactivation of GSK3 by Lyn as well as Jak2-V617F and additionally through activation of STAT5 by Jak2-V617F. It is also speculated that activation of the mTOR/p70S6K/4EBP1 pathway may mediate proliferation signaling from Jak2-V617F and Lyn. PVTL-1 cells may provide a valuable model system to elucidate the molecular mechanisms involved in evolution of Jak2-V617F-expressing MPN to AML and to develop novel therapies against this intractable condition.

Glycogen synthase kinase-3 (GSK3) controls deoxyglucose-induced mitochondrial biogenesis in human neuroblastoma SH-SY5Y cells

Mitochondrial biogenesis, a mitochondrial growth and division process, is crucial for adaptation to metabolic stress. The present study demonstrated that treatment with a specific inhibitor of GSK3, SB216763, attenuated induction of mitochondrial biogenesis by a glycolysis inhibitor, 2-deoxyglucose (2-DG), without affecting this biogenesis at basal condition. Additionally, overexpression of WT-GSK3β promoted whereas GSK3β-KD attenuated 2-DG-induced mitochondrial protein expression. The mitochondrial biogenesis attenuation by GSK3 inhibitor was not due to inhibition of protein degradation. Furthermore, GSK3 inhibition further reduced transcription of mitochondrial (COXII), but not nuclear (VDAC) gene by 2-DG suggesting its participation in 2-DG-induced mitochondrial transcription. Together, our results show that GSK3 regulates mitochondrial biogenesis induced by glycolysis inhibition.

Concerted suppression of STAT3 and GSK3β is involved in growth inhibition of non-small cell lung cancer by Xanthatin

Xanthatin, a sesquiterpene lactone purified from Xanthium strumarium L., possesses prominent anticancer activity. We found that disruption of GSK3β activity was essential for xanthatin to exert its anticancer properties in non-small cell lung cancer (NSCLC), concurrent with preferable suppression of constitutive activation of STAT3. Interestingly, inactivation of the two signals are two mutually exclusive events in xanthatin-induced cell death. Moreover, we surprisingly found that exposure of xanthatin failed to trigger the presumable side effect of canonical Wnt/β-Catenin followed by GSK3β inactivation. We further observed that the downregulation of STAT3 was required for xanthatin to fine-tune the risk. Thus, the discovery of xanthatin, which has ability to simultaneously orchestrate two independent signaling cascades, may have important implications for screening promising drugs in cancer therapies.

Insulin and IGF1 enhance IL-17-induced chemokine expression through a GSK3B-dependent mechanism: a new target for melatonin's anti-inflammatory action

Obesity is a chronic inflammation with increased serum levels of insulin, insulin-like growth factor 1 (IGF1), and interleukin-17 (IL-17). The objective of this study was to test a hypothesis that insulin and IGF1 enhance IL-17-induced expression of inflammatory chemokines/cytokines through a glycogen synthase kinase 3β (GSK3B)-dependent mechanism, which can be inhibited by melatonin. We found that insulin/IGF1 and lithium chloride enhanced IL-17-induced expression of C-X-C motif ligand 1 (Cxcl1) and C-C motif ligand 20 (Ccl20) in the Gsk3b(+/+) , but not in Gsk3b(-/-) mouse embryonic fibroblast (MEF) cells. IL-17 induced higher levels of Cxcl1 and Ccl20 in the Gsk3b(-/-) MEF cells, compared with the Gsk3b(+/+) MEF cells. Insulin and IGF1 activated Akt to phosphorylate GSK3B at serine 9, thus inhibiting GSK3B activity. Melatonin inhibited Akt activation, thus decreasing P-GSK3B at serine 9 (i.e., increasing GSK3B activity) and subsequently inhibiting expression of Cxcl1 and Ccl20 that was induced either by IL-17 alone or by a combination of insulin and IL-17. Melatonin's inhibitory effects were only observed in the Gsk3b(+/+) , but in not Gsk3b(-/-) MEF cells. Melatonin also inhibited expression of Cxcl1, Ccl20, and Il-6 that was induced by a combination of insulin and IL-17 in the mouse prostatic tissues. Further, nighttime human blood, which contained high physiologic levels of melatonin, decreased expression of Cxcl1, Ccl20, and Il-6 in the PC3 human prostate cancer xenograft tumors. Our data support our hypothesis and suggest that melatonin may be used to dampen IL-17-mediated inflammation that is enhanced by the increased levels of insulin and IGF1 in obesity.

Intracellular ion channels and cancer

Several types of channels play a role in the maintenance of ion homeostasis in subcellular organelles including endoplasmatic reticulum, nucleus, lysosome, endosome, and mitochondria. Here we give a brief overview of the contribution of various mitochondrial and other organellar channels to cancer cell proliferation or death. Much attention is focused on channels involved in intracellular calcium signaling and on ion fluxes in the ATP-producing organelle mitochondria. Mitochondrial K⁺ channels (Ca²⁺-dependent BK_Ca and IK_Ca, ATP-dependent K_ATP, Kv1.3, two-pore TWIK-related Acid-Sensitive K⁺ channel-3 (TASK-3)), Ca²⁺ uniporter MCU, Mg²⁺-permeable Mrs2, anion channels (voltage-dependent chloride channel VDAC, intracellular chloride channel CLIC) and the Permeability Transition Pore (MPTP) contribute importantly to the regulation of function in this organelle. Since mitochondria play a central role in apoptosis, modulation of their ion channels by pharmacological means may lead to death of cancer cells. The nuclear potassium channel Kv10.1 and the nuclear chloride channel CLIC4 as well as the endoplasmatic reticulum (ER)-located inositol 1,4,5-trisphosphate (IP₃) receptor, the ER-located Ca²⁺ depletion sensor STIM1 (stromal interaction molecule 1), a component of the store-operated Ca²⁺ channel and the ER-resident TRPM8 are also mentioned. Furthermore, pharmacological tools affecting organellar channels and modulating cancer cell survival are discussed. The channels described in this review are summarized on Figure 1. Overall, the view is emerging that intracellular ion channels may represent a promising target for cancer treatment.

Activator or inhibitor? GSK-3 as a new drug target

Glycogen synthase kinase-3 (GSK-3) is a cytoplasmic serine/threonine protein kinase that phosphorylates and inhibits glycogen synthase, thereby inhibiting glycogen synthesis from glucose. However, this serine/threonine kinase is now known to regulate numerous cellular processes through a number of signaling pathways important for cell proliferation, stem cell renewal, apoptosis and development. Because of these diverse roles, malfunction of this kinase is also known to be involved in the pathogenesis of human diseases, such as nervous system disorders, diabetes, bone formation, inflammation, cancer and heart failure. Therefore, GSK-3 is recognized as an attractive target for the development of new drugs. The present review summarizes the roles of GSK-3 in the insulin, Wnt/β-catenin and hedgehog signaling pathways including the regulation of their activities. The roles of GSK-3 in the development of human diseases within the context of its participation in various signaling pathways are also summarized. Finally, the possibility of new drug development targeting this kinase is discussed with recent information about inhibitors and activators of GSK-3.