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The vacuolar-type H+-ATPase (v-ATPase) is the major proton pump that acidifies intracellular compartments of eukaryotic cells. Since the inhibition of v-ATPase resulted in anti-tumor and anti-metastatic effects in different tumor models, this enzyme has emerged as promising strategy against cancer. Here, we used the well-established v-ATPase inhibitor archazolid, a natural product first isolated from the myxobacterium Archangium gephyra, to study the consequences of v-ATPase inhibition in endothelial cells (ECs), in particular on the interaction between ECs and cancer cells, which has been neglected so far. Human endothelial cells treated with archazolid showed an increased adhesion of tumor cells, whereas the transendothelial migration of tumor cells was reduced. The adhesion process was independent from the EC adhesion molecules ICAM-1, VCAM-1, E-selectin and N-cadherin. Instead, the adhesion was mediated by β1-integrins expressed on tumor cells, as blocking of the integrin β1 subunit reversed this process. Tumor cells preferentially adhered to the β1-integrin ligand collagen and archazolid led to an increase in the amount of collagen on the surface of ECs. The accumulation of collagen was accompanied by a strong decrease of the expression and activity of the protease cathepsin B. Overexpression of cathepsin B in ECs prevented the capability of archazolid to increase the adhesion of tumor cells onto ECs. Our study demonstrates that the inhibition of v-ATPase by archazolid induces a pro-adhesive phenotype in endothelial cells that promotes their interaction with cancer cells, whereas the transmigration of tumor cells was reduced. These findings further support archazolid as a promising anti-metastatic compound.
More than 70 human adenoviruses with type-dependent pathogenicity have been identified but biological information about the majority of these virus types is scarce. Here we employed multiple sequence alignments and structural information to predict receptor usage for the development of an adenoviral vector with novel biological features. We report the generation of a cloned adenovirus based on human adenovirus type 17 (HAdV17) with high sequence homology to the well characterized human adenovirus type 37 (HAdV37) that causes epidemic keratoconjunctivitis (EKC). Our study revealed that human CD46 (CD46) is involved in cell entry of HAdV17. Moreover, we found that HAdV17 infects endothelial cells (EC) in vitro including primary cells at higher efficiencies compared to the commonly used human adenovirus type 5 (HAdV5). Using a human CD46 transgenic mouse model, we observed that HAdV17 displays a broad tropism in vivo after systemic injection and that it transduces ECs in this mouse model. We conclude that the HAdV17-based vector may provide a novel platform for gene therapy.
The liver as the biggest endocrine gland of the human body plays a central role in many metabolic pathways such as detoxification, storage of carbohydrates and distribution of lipids. As the liver receives blood supply from the gut by the portal vein, liver cells are often challenged with high concentrations of nutrients and components of our commensal microbiota. Therefore, the immune system of the liver induces a tolerant state, meaning no or low inflammatory reactions to those constant stimuli. Yet, as various pathogens target the liver, the hepatic immune system also needs the capability to induce strong immune responses quickly. Chronical damage to the liver, which can be caused by alcohol, pathogens or toxins, might lead to liver cirrhosis, where the amount of functional liver tissue is decreased dramatically. This pathology can worsen and lead to acute-on-chronic liver failure, whose high mortality is due to high inflammation and multi-organ failure. Interleukin-7 is a cytokine known for its pro-survival functions especially in lymphopoiesis. However, it is also very important for maintenance of mature immune cells in the liver. As mouse experiments have demonstrated an induction of Interleukin-7 in the liver as a response to bacterial lipopolysaccharide, we aimed to characterize the role of Interleukin-7 in hepatic immunoregulation in both health and disease.
The experiments were mostly based on in vitro approaches. Induction of Interleukin-7 in liver cells was analyzed using ELISA, quantitative PCR, and Immunoblotting. Knockdown of signal transduction components was performed by siRNA transfection. Primary immune cells isolated from healthy donor buffy coat were studied for their ability to respond to Interleukin-7. Activation of downstream signal transduction was assessed by Immunoblotting. Functional consequences of Interleukin-7 signaling, such as alterations in cellular metabolism, cellular survival and endotoxin tolerance, were studied in monocyte-derived macrophages. Finally, serum concentrations of Interleukin-7 and frequencies of Interleukin-7 receptor positive immune cells were quantified in patients with compensated or decompensated liver cirrhosis or acute-on-chronic liver failure.
Interleukin-7 expression could be observed in human hepatic cell lines and primary hepatic sinusoidal endothelial cells when stimulated with IFNα or IFNγ, but not IFNλ. IRF-1 was identified as a key regulator of Interleukin-7 expression, as its transcription, translation and nuclear translocation were induced and enhanced upon IFNα or IFNγ, but not IFNλ treatment. We identified LPS-primed macrophages as innate immune target cells of Interleukin-7, which responded by an inhibitory phosphorylation of GSK3. This signal transduction led to enhanced production of pro-inflammatory cytokines and abolished endotoxin tolerance. In parallel, cellular fitness was reduced as demonstrated by reduced intracellular ATP concentration and intracellular WST-1 staining. Finally, we could identify components of the in vitro signal transduction also in liver cirrhosis patients. However, Interleukin-7 serum concentrations were significantly in liver cirrhosis patients compared to healthy controls. In addition, the frequencies of Interleukin-7 receptor positive immune cell populations differed in patients and controls.
We identify Interleukin-7 as a pro-inflammatory cytokine in hepatic immunoregulation. It is part of a cascade where its induction is regulated by type I and type II Interferons and mainly restricted by the presence of IRF1. We demonstrate the importance of Interleukin-7 also for innate immune cells, where the abolishment of endotoxin tolerance may provide an interesting strategy of liver cirrhosis patients. In addition, reduced viability of macrophages in response to Interleukin-7 is a striking contrast to the well-described survival functions in lymphocytes. The decrease of serum Interleukin-7 levels and alterations of Interleukin-7 receptor positive immune cell populations suggest an important role for Interleukin-7 also in the diseased liver. Due to the identified mechanisms of action, Interleukin-7 may be an interesting candidate for immunotherapeutic approaches of liver cirrhosis and acute-on-chronic liver failure.
Although the Nobel Prize for the discovery of nitric oxide (NO) dates back almost 20 years now, the knowledge about cGMP signaling is still constantly increasing. It looks even so that our understanding of the role of the soluble guanylyl cyclase (sGC) and particulate guanylyl cyclase (pGC) in health and disease is in many aspects at the beginning and far from being understood. This holds even true for the therapeutic impact of innovative drugs acting on both the NO/sGC and the pGC pathways. Since cGMP, as second messenger, is involved in the pathogenesis of numerous diseases within the cardiovascular, pulmonary, renal, and endocrine systems and also plays a role in neuronal, sensory, and tumor processes, drug applications might be quite broad. On the 8th International Conference on cGMP, held in Bamberg, Germany, world leading experts came together to discuss these topics. All aspects of cGMP research from the basic understanding of cGMP signaling to clinical applicability were discussed in depth. In addition, present and future therapeutic applications of cGMP-modulating pharmacotherapy were presented (http://www.cyclicgmp.net/index.html).
The bile acid activated transcription factor farnesoid X receptor (FXR) regulates numerous metabolic processes and is a rising target for the treatment of hepatic and metabolic disorders. FXR agonists have revealed efficacy in treating non-alcoholic steatohepatitis (NASH), diabetes and dyslipidemia. Here we characterize imatinib as first-in-class allosteric FXR modulator and report the development of an optimized descendant that markedly promotes agonist induced FXR activation in a reporter gene assay and FXR target gene expression in HepG2 cells. Differential effects of imatinib on agonist-induced bile salt export protein and small heterodimer partner expression suggest that allosteric FXR modulation could open a new avenue to gene-selective FXR modulators.
The prediction of protein–ligand interactions and their corresponding binding free energy is a challenging task in structure-based drug design and related applications. Docking and scoring is broadly used to propose the binding mode and underlying interactions as well as to provide a measure for ligand affinity or differentiate between active and inactive ligands. Various studies have revealed that most docking software packages reliably predict the binding mode, although scoring remains a challenge. Here, a diverse benchmark data set of 99 matched molecular pairs (3D-MMPs) with experimentally determined X-ray structures and corresponding binding affinities is introduced. This data set was used to study the predictive power of 13 commonly used scoring functions to demonstrate the applicability of the 3D-MMP data set as a valuable tool for benchmarking scoring functions.
Tight regulation of inflammation is very important to guarantee a balanced immune response without developing chronic inflammation. One of the major mediators of the resolution of inflammation is the transcription factor: the nuclear factor erythroid 2-like 2 (Nrf2). Stabilized following oxidative stress, Nrf2 induces the expression of antioxidants as well as cytoprotective genes, which provoke an anti-inflammatory expression profile, and is crucial for the initiation of healing. In view of this fundamental modulatory role, it is clear that both hyper- or hypoactivation of Nrf2 contribute to the onset of chronic diseases. Understanding the tight regulation of Nrf2 expression/activation and its interaction with signaling pathways, known to affect inflammatory processes, will facilitate development of therapeutic approaches to prevent Nrf2 dysregulation and ameliorate chronic inflammatory diseases. We discuss in this review the principle mechanisms of Nrf2 regulation with a focus on inflammation and autophagy, extending the role of dysregulated Nrf2 to chronic diseases and tumor development.
Proteins and glycolipids have been found to be decorated with phosphorylcholine (PC) both in protozoa and nematodes that parasitize humans and animals. PC epitopes can provoke various effects on immune cells leading to an immunomodulation of the host’s immune system that allows long-term persistence of the parasites. So far, only a limited number of PC-modified proteins, mainly from nematodes, have been identified. Infections caused by Leishmania spp. (e.g., L. infantum in southern Europe) affect about 12 million people worldwide and are characterized by a wide spectrum of clinical forms in humans, ranging from cutaneous to fatal visceral leishmaniasis. To establish and maintain the infection, these protozoa are dependent on the secretion of effector molecules into the host for modulating their immune system. In this project, we analyzed the PC modification of L. infantum promastigotes by 2D-gel based proteomics. Western blot analysis with the PC-specific antibody TEPC-15 revealed one PC-substituted protein in this organism, identified as eEF1α. We could demonstrate that the binding of eEF1α to one of its downstream effectors is dependent on its PC-modification. In this study we provide evidence that in this parasite the modification of eEF1α with PC may be essential for its function as an important virulence factor.
Mechanistic modeling of in vitro data generated from metabolic enzyme systems (viz., liver microsomes, hepatocytes, rCYP enzymes, etc.) facilitates in vitro–in vivo extrapolation (IVIV_E) of metabolic clearance which plays a key role in the successful prediction of clearance in vivo within physiologically-based pharmacokinetic (PBPK) modeling. A similar concept can be applied to solubility and dissolution experiments whereby mechanistic modeling can be used to estimate intrinsic parameters required for mechanistic oral absorption simulation in vivo. However, this approach has not widely been applied within an integrated workflow. We present a stepwise modeling approach where relevant biopharmaceutics parameters for ketoconazole (KTZ) are determined and/or confirmed from the modeling of in vitro experiments before being directly used within a PBPK model. Modeling was applied to various in vitro experiments, namely: (a) aqueous solubility profiles to determine intrinsic solubility, salt limiting solubility factors and to verify pKa; (b) biorelevant solubility measurements to estimate bile-micelle partition coefficients; (c) fasted state simulated gastric fluid (FaSSGF) dissolution for formulation disintegration profiling; and (d) transfer experiments to estimate supersaturation and precipitation parameters. These parameters were then used within a PBPK model to predict the dissolved and total (i.e., including the precipitated fraction) concentrations of KTZ in the duodenum of a virtual population and compared against observed clinical data. The developed model well characterized the intraluminal dissolution, supersaturation, and precipitation behavior of KTZ. The mean simulated AUC0–t of the total and dissolved concentrations of KTZ were comparable to (within 2-fold of) the corresponding observed profile. Moreover, the developed PBPK model of KTZ successfully described the impact of supersaturation and precipitation on the systemic plasma concentration profiles of KTZ for 200, 300, and 400 mg doses. These results demonstrate that IVIV_E applied to biopharmaceutical experiments can be used to understand and build confidence in the quality of the input parameters and mechanistic models used for mechanistic oral absorption simulations in vivo, thereby improving the prediction performance of PBPK models. Moreover, this approach can inform the selection and design of in vitro experiments, potentially eliminating redundant experiments and thus helping to reduce the cost and time of drug product development.
Background: Drugs used to treat gastrointestinal diseases (GI drugs) are widely used either as prescription or over23 the-counter (OTC) medications and belong to both the ten most prescribed and ten most sold OTC medications worldwide. Current clinical practice shows that in many cases, these drugs are administered concomitantly with other drug products. Due to their metabolic properties and mechanisms of action, the drugs used to treat gastrointestinal diseases can change the pharmacokinetics of some co27 administered drugs. In certain cases, these interactions can lead to failure of treatment or to the occurrence of serious adverse events. The mechanism of interaction depends highly on drug properties and differs among therapeutic categories. Understanding these interactions is essential to providing recommendations for optimal drug therapy.
Objective: To discuss the most frequent interactions between GI and other drugs, including identification of the mechanisms behind these interactions, where possible.
Conclusion: Interactions with GI drugs are numerous and can be highly significant clinically. Whilst alterations in bioavailability due to changes in solubility, dissolution rate and metabolic interactions can be (for the most part) easily identified, interactions that are mediated through other mechanisms, such as permeability or microbiota, are less well understood. Future work should focus on characterizing these aspects.
While interleukin (IL)-1β is a potent pro-inflammatory cytokine involved in host defense, high levels can cause life-threatening sterile inflammation including systemic inflammatory response syndrome. Hence, the control of IL-1β secretion is of outstanding biomedical importance. In response to a first inflammatory stimulus such as lipopolysaccharide, pro-IL-1β is synthesized as a cytoplasmic inactive pro-form. Extracellular ATP originating from injured cells is a prototypical second signal for inflammasome-dependent maturation and release of IL-1β. The human anti-protease alpha-1 antitrypsin (AAT) and IL-1β regulate each other via mechanisms that are only partially understood. Here, we demonstrate that physiological concentrations of AAT efficiently inhibit ATP-induced release of IL-1β from primary human blood mononuclear cells, monocytic U937 cells, and rat lung tissue, whereas ATP-independent IL-1β release is not impaired. Both, native and oxidized AAT are active, suggesting that the inhibition of IL-1β release is independent of the anti-elastase activity of AAT. Signaling of AAT in monocytic cells involves the lipid scavenger receptor CD36, calcium-independent phospholipase A2β, and the release of a small soluble mediator. This mediator leads to the activation of nicotinic acetylcholine receptors, which efficiently inhibit ATP-induced P2X7 receptor activation and inflammasome assembly. We suggest that AAT controls ATP-induced IL-1β release from human mononuclear blood cells by a novel triple-membrane-passing signaling pathway. This pathway may have clinical implications for the prevention of sterile pulmonary and systemic inflammation.
Der Name Histamin hat seinen Ursprung aus dem griechischen Wort "histos" (Gewebe) und spielt auf sein breites Spektrum an Aktivitäten, sowohl unter physiologischen als auch unter pathophysiologischen Bedingungen an. Histamin ist eines der Moleküle mit welchem man sich im letzten Jahrhundert am intensivsten beschäftigt hat.
Im Jahr 1907 wurde das Histamin erstmals synthetisiert. Drei Jahre später gelang es, dieses Monoamin erstmals aus dem Mutterkornpilz Claviceps purpurea zu isolieren. Weitere 17 Jahre vergingen, ehe Best et al. Histamin aus der humanen Leber und der humanen Lunge isolieren konnten. Best konnte somit beweisen, dass dieses biogene Amin einen natürlichen Bestandteil des menschlichen Körpers darstellt. Nach der Entdeckung wurden dem Histamin mehrere Effekte zugeschrieben. Dale et al. beobachteten, dass Histamin einen stimulierenden Effekt auf die glatte Muskulatur des Darms und des Respirationstraktes hat, stimulierend auf die Herzkontraktion wirkt, Vasodepression und ein schockähnliches Syndrom verursacht.
Popielski demonstrierte, dass Histamin dosisabhängig einen stimulierenden Effekt auf die Magensäuresekretion von Hunden hat. Lewis wiederum beschrieb erstmals, dass Histamin einen Effekt auf der Haut hervorruft. Dies zeigte sich durch verschiedene Merkmale, wie geröteter Bereich aufgrund der Vasodilatation und Quaddeln aufgrund der erhöhten Gefäßpermeabilität. Des Weiteren wurde Histamin eine mediatorische Eigenschaft bei anaphylaktischen und allergischen Reaktionen zugeschrieben. Zusätzlich spielt das biogene Amin eine entscheidende Rolle im zentralen Nervensystem (ZNS), unter anderem beim Lernen, bei der Erinnerung, beim Appetit und beim Schlaf-Wach-Rhythmus. Von den zahlreichen physiologischen Effekten des Histamins ist seine Rolle bei Entzündungsprozessen, der Magensäuresekretion und als Neurotransmitter am besten verstanden.
Many cancers have the tumor suppressor p53 inactivated by mutation, making reactivation of mutant p53 with small molecules a promising strategy for the development of novel anticancer therapeutics. The oncogenic p53 mutation Y220C, which accounts for approximately 100,000 cancer cases per year, creates an extended surface crevice in the DNA-binding domain, which destabilizes p53 and causes denaturation and aggregation. Here, we describe the structure-guided design of a novel class of small-molecule Y220C stabilizers and the challenging synthetic routes developed in the process. The synthesized chemical probe MB710, an aminobenzothiazole derivative, binds tightly to the Y220C pocket and stabilizes p53-Y220C in vitro. MB725, an ethylamide analogue of MB710, induced selective viability reduction in several p53-Y220C cancer cell lines while being well tolerated in control cell lines. Reduction of viability correlated with increased and selective transcription of p53 target genes such as BTG2, p21, PUMA, FAS, TNF, and TNFRSF10B, which promote apoptosis and cell cycle arrest, suggesting compound-mediated transcriptional activation of the Y220C mutant. Our data provide a framework for the development of a class of potent, non-toxic compounds for reactivating the Y220C mutant in anticancer therapy.
Acute myeloid leukemia (AML) is characterized by uncontrolled proliferation and accumulation of immature myeloblasts, which impair normal hematopoiesis. While this definition categorizes the disease into a distinctive group, the large number of different genetic and epigenetic alterations actually suggests that AML is not a single disease, but a plethora of malignancies. Still, most AML patients are not treated with targeted medication but rather by uniform approaches such as chemotherapy. The identification of novel treatment options likely requires the identification of cancer cell vulnerabilities that take into account the different genetic and epigenetic make-up of the individual tumors. Here we show that STK3 depletion by knock-down, knock-out or chemical inhibition results in apoptotic cells death in some but not all AML cell lines and primary cells tested. This effect is mediated by a premature activation of cyclin dependent kinase 1 (CDK1) in presence of elevated cyclin B1 levels. The anti-leukemic effects seen in both bulk and progenitor AML cells suggests that STK3 might be a promising target in a subset of AML patients.
UPF1 regulates myeloid cell functions and S100A9 expression by the hnRNP E2/miRNA-328 balance
(2016)
UPF1 is a key player in nonsense mediated mRNA decay (NMD) but also involved in posttranscriptional gene regulation. In this study we found that UPF1 regulates the expression of genes with functions in inflammation and myeloid cell differentiation via hnRNP E2. The majority of the UPF1-regulated genes identified in monocytic cells contain a binding site for hnRNP E2 within 5′ UTR located introns with hnRNP E2 acting here as splicing regulator. We found that miRNA-328 which is significantly induced during monocytic cell differentiation acts independently from its gene silencing function as RNA decoy for hnRNP E2. One representative gene controlled by the hnRNP E2/miRNA-328 balance is S100A9 which plays an important role in cell differentiation and oxidative stress response of monocytes. Induction of miRNA-328 expression during cell differentiation antagonizes the blockade by hnRNP E2 which results in the upregulation of CD11b expression and ROS production in monocytic cells. Taken together, our data indicate that upregulation of miR-328 is responsible for the induction of hnRNP E2 target genes during myeloid cell differentiation.
Cdc2-like kinases (CLKs) represent a family of serine-threonine kinases involved in the regulation of splicing by phosphorylation of SR-proteins and other splicing factors. Although compounds acting against CLKs have been described, only a few show selectivity against dual-specificity tyrosine phosphorylation regulated-kinases (DYRKs). We here report a novel CLK inhibitor family based on a 6,7-dihydropyrrolo[3,4-g]indol-8(1H)-one core scaffold. Within the series, 3-(3-chlorophenyl)-6,7-dihydropyrrolo[3,4-g]indol-8(1H)-one (KuWal151) was identified as inhibitor of CLK1, CLK2 and CLK4 with a high selectivity margin towards DYRK kinases. The compound displayed a potent antiproliferative activity in an array of cultured cancer cell lines. The X-ray structure analyses of three members of the new compound class co-crystallized with CLK proteins corroborated a molecular binding mode predicted by docking studies.
Biosynthetic human insulin and insulin analogues are the mainstay of insulin therapy for both type 1 and type 2 diabetes although access to human insulin at affordable prices remains a global issue. The world is experiencing an exponential rise in the prevalence of diabetes presenting an urgent need to establish effective diabetes therapy in countries burdened by inadequate health care budgets, malnutrition and infectious diseases. Recombinant human insulin has replaced animal insulins and animal-based semisynthetic human insulin thereby available in sufficient quantities and at affordable prices able to provide global access to insulin therapy. In many patients, analog insulins can offer additional clinical benefit, although at a considerably higher price thus severely restricting availability in low income countries. The approval process for recombinant human insulins (i.e. biosimilars) and analogue insulins is highly variable in the developing countries in contrast to Europe and in North America, where it is well established within a strict regulatory framework. This review aims to discuss the future access to human insulin therapy in a global context with an ever increasing burden of diabetes and significant economic implications.
Acute myeloid leukemia (AML) is a clonal malignancy of hematopoietic stem cells (HSCs) characterized by expansion of myeloid blasts in the bone marrow. It has been shown that autophagy is a degradative process, which delivers cytoplasmic components to lysosomes to prevent malignant transformation by maintaining HSC integrity. Besides its function as a bulk degradation machinery to recycle cytoplasmic components during limited energy supply, autophagy also serves as an intracellular quality control mechanism. Selective autophagy requires autophagy receptors such as p62 to specifically bridge the targeted cargos into autophagosomes. p62 is known as a central signaling hub involved in pro-oncogenic signaling pathways and autophagic degradation pathways. However, little is known about the role of p62 as a selective autophagy receptor in AML. This study aims to elucidate the precise function of p62 as an autophagy receptor in leukemia development and maintenance.
In silico analysis revealed that high p62 expression was significantly associated with poor overall survival of adult patients with de novo AML, suggesting that p62 may promote leukemia maintenance. To address the functional role of p62 in leukemia, genome editing by CRISPR/Cas9 was used to knockout p62 in four human AML cell lines. Importantly, p62 loss reduced cell proliferation in all four cell lines. This observation could be transferred to a murine leukemia cell model in which leukemic transformation of lineage-depleted bone marrow (ldMBM) cells was induced by overexpression of the human transcriptional coactivator MN1. Knockdown of p62 by shRNA in MN1-driven leukemia cells impaired proliferation and decreased colony forming ability without altering apoptosis. This indicates that p62 is crucial for leukemia proliferation in vitro. To further characterize the role of p62 in leukemia development and maintenance a murine AML transplantation model was established. Therefore, ldMBM cells isolated from WT and p62-/- mice were transduced with MN1 and transplanted into lethally irradiated mice. As expected, all mice developed fatal myeloid proliferation. Notably, p62 loss in MN1-driven leukemia significantly prolonged survival in mice and caused a more immature phenotype. Consistent with the in vitro results, ex vivo analysis of p62-/- leukemic cells displayed decreased colony-forming ability, although p62 loss did not affect composition and function of HSCs. Moreover, re-transplantation of primary MN1-driven leukemia cells attenuated leukemia progression upon p62 loss. These findings support a decisive role of p62 in leukemia development and maintenance.
To gain molecular insight into the function of p62 during myeloid transformation an interactome analysis of murine MN1-driven leukemia cells was performed. This revealed first that p62 predominantly interacts with mitochondrial proteins and second that inhibition of autophagic degradation causes accumulation of p62-bound mitochondria. This leads to the first assumption that loss of p62 may provoke mitochondrial accumulation with increasing mitochondrial damage and second that p62 may mediate degradation of mitochondria by mitophagy. Indeed, in the absence of p62, accumulation of dysfunctional mitochondria was detected by morphological changes of the mitochondria, increased mitochondrial ROS and impaired mitochondrial respiration capacity. Furthermore, induction of PINK1/Parkin-independent mitophagy revealed that loss of p62 caused impaired degradation of mitochondrial proteins and reduced translocation of damaged mitochondria into autophagosomes. Taken together, p62 is required for effective degradation of dysfunctional mitochondria by mitophagy in AML.
Due to the fact that p62 is a multifunctional protein, rescue experiments with different mutants of p62 were performed to clarify if p62-mediated mitophagy contributes to leukemia proliferation. Notably, the autophagy-deficient mutant (disabled to bind autophagosomes) reduced cell growth and colony-forming ability to the same extent as knockdown of p62, as the clustering-deficient mutant (disabled to form aggregates) displayed an intermediate phenotype. Strikingly, only the autophagy-deficient mutant failed to rescue mitophagy.
In conclusion, this study demonstrates the prominent role of p62 as a selective autophagy receptor for mitochondrial quality control which contributes to leukemia development and maintenance. Therefore, targeting selective autophagy opens new venues in the treatment of AML.
Androgen receptor deregulation drives bromodomain-mediated chromatin alterations in prostate cancer
(2017)
Global changes in chromatin accessibility may drive cancer progression by reprogramming transcription factor (TF) binding. In addition, histone acetylation readers such as bromodomain-containing protein 4 (BRD4) have been shown to associate with these TFs and contribute to aggressive cancers including prostate cancer (PC). Here, we show that chromatin accessibility defines castration-resistant prostate cancer (CRPC). We show that the deregulation of androgen receptor (AR) expression is a driver of chromatin relaxation and that AR/androgen-regulated bromodomain-containing proteins (BRDs) mediate this effect. We also report that BRDs are overexpressed in CRPCs and that ATAD2 and BRD2 have prognostic value. Finally, we developed gene stratification signature (BROMO-10) for bromodomain response and PC prognostication, to inform current and future trials with drugs targeting these processes. Our findings provide a compelling rational for combination therapy targeting bromodomains in selected patients in which BRD-mediated TF binding is enhanced or modified as cancer progresses.