Showing papers by "Guido Kroemer published in 2014"
TL;DR: The dialogue between autophagy and cell death pathways influences the normal clearance of dying cells, as well as immune recognition of dead cell antigens, and the disruption of the relationship between autphagy and apoptosis has important pathophysiological consequences.
Abstract: Autophagy and apoptosis control the turnover of organelles and proteins within cells, and of cells within organisms, respectively, and many stress pathways sequentially elicit autophagy, and apoptosis within the same cell. Generally autophagy blocks the induction of apoptosis, and apoptosis-associated caspase activation shuts off the autophagic process. However, in special cases, autophagy or autophagy-relevant proteins may help to induce apoptosis or necrosis, and autophagy has been shown to degrade the cytoplasm excessively, leading to 'autophagic cell death'. The dialogue between autophagy and cell death pathways influences the normal clearance of dying cells, as well as immune recognition of dead cell antigens. Therefore, the disruption of the relationship between autophagy and apoptosis has important pathophysiological consequences.
1,721 citations
Istituto Superiore di Sanità1, Université Paris-Saclay2, Paris Descartes University3, Institut Gustave Roussy4, University of Bonn5, University Hospital Bonn6, École Polytechnique Fédérale de Lausanne7, Yale University8, University of Auvergne9, University of Burgundy10, Università telematica San Raffaele11, Harvard University12, Centre national de la recherche scientifique13, Washington University in St. Louis14, QIMR Berghofer Medical Research Institute15
TL;DR: The data suggest that anthracycline-mediated immune responses mimic those induced by viral pathogens, and it is surmised that such 'viral mimicry' constitutes a hallmark of successful chemotherapy.
Abstract: Some of the anti-neoplastic effects of anthracyclines in mice originate from the induction of innate and T cell-mediated anticancer immune responses. Here we demonstrate that anthracyclines stimulate the rapid production of type I interferons (IFNs) by malignant cells after activation of the endosomal pattern recognition receptor Toll-like receptor 3 (TLR3). By binding to IFN-α and IFN-β receptors (IFNARs) on neoplastic cells, type I IFNs trigger autocrine and paracrine circuitries that result in the release of chemokine (C-X-C motif) ligand 10 (CXCL10). Tumors lacking Tlr3 or Ifnar failed to respond to chemotherapy unless type I IFN or Cxcl10, respectively, was artificially supplied. Moreover, a type I IFN-related signature predicted clinical responses to anthracycline-based chemotherapy in several independent cohorts of patients with breast carcinoma characterized by poor prognosis. Our data suggest that anthracycline-mediated immune responses mimic those induced by viral pathogens. We surmise that such 'viral mimicry' constitutes a hallmark of successful chemotherapy.
785 citations
TL;DR: The physiological regulation of autophagy by metabolic circuitries, as well as alterations of such control in disease are discussed.
685 citations
Institut Gustave Roussy1, University of São Paulo2, Katholieke Universiteit Leuven3, University of Burgundy4, Sapienza University of Rome5, Istituto Superiore di Sanità6, Vrije Universiteit Brussel7, University of Manchester8, University of Michigan9, National University of Cuyo10, Pierre-and-Marie-Curie University11, New York University12, University of Salento13, University of Crete14, Charles University in Prague15, University of Erlangen-Nuremberg16, University Hospital Heidelberg17, University of Pittsburgh18, University of Helsinki19, National Institutes of Health20, University of Bonn21, Providence Portland Medical Center22, National University of Singapore23, Ghent University24, University of Milan25, University of Graz26, University of Paris-Sud27, University College London28, Tuscia University29, McMaster University30, Technische Universität München31, Medical University of Vienna32, Karolinska Institutet33, University of Nice Sophia Antipolis34, University of Turin35, QIMR Berghofer Medical Research Institute36, Université de Montréal37, Dow University of Health Sciences38, French Institute of Health and Medical Research39, University of Colorado Denver40, University of Hawaii41, Stony Brook University42, Paris Descartes University43
TL;DR: Strategies conceived to detect surrogate markers of ICD in vitro and to screen large chemical libraries for putative I CD inducers are outlined, based on a high-content, high-throughput platform that was recently developed.
Abstract: Apoptotic cells have long been considered as intrinsically tolerogenic or unable to elicit immune responses specific for dead cell-associated antigens. However, multiple stimuli can trigger a functionally peculiar type of apoptotic demise that does not go unnoticed by the adaptive arm of the immune system, which we named "immunogenic cell death" (ICD). ICD is preceded or accompanied by the emission of a series of immunostimulatory damage-associated molecular patterns (DAMPs) in a precise spatiotemporal configuration. Several anticancer agents that have been successfully employed in the clinic for decades, including various chemotherapeutics and radiotherapy, can elicit ICD. Moreover, defects in the components that underlie the capacity of the immune system to perceive cell death as immunogenic negatively influence disease outcome among cancer patients treated with ICD inducers. Thus, ICD has profound clinical and therapeutic implications. Unfortunately, the gold-standard approach to detect ICD relies on vaccination experiments involving immunocompetent murine models and syngeneic cancer cells, an approach that is incompatible with large screening campaigns. Here, we outline strategies conceived to detect surrogate markers of ICD in vitro and to screen large chemical libraries for putative ICD inducers, based on a high-content, high-throughput platform that we recently developed. Such a platform allows for the detection of multiple DAMPs, like cell surface-exposed calreticulin, extracellular ATP and high mobility group box 1 (HMGB1), and/or the processes that underlie their emission, such as endoplasmic reticulum stress, autophagy and necrotic plasma membrane permeabilization. We surmise that this technology will facilitate the development of next-generation anticancer regimens, which kill malignant cells and simultaneously convert them into a cancer-specific therapeutic vaccine.
665 citations
TL;DR: Recent systems biology studies aimed at deconvoluting the complex circuitries that underpin cisplatin resistance are discussed, and how their findings might drive the development of rational approaches to tackle this clinically relevant problem.
Abstract: The platinum derivative cis-diamminedichloroplatinum(II), best known as cisplatin, is currently employed for the clinical management of patients affected by testicular, ovarian, head and neck, colorectal, bladder and lung cancers. For a long time, the antineoplastic effects of cisplatin have been fully ascribed to its ability to generate unrepairable DNA lesions, hence inducing either a permanent proliferative arrest known as cellular senescence or the mitochondrial pathway of apoptosis. Accumulating evidence now suggests that the cytostatic and cytotoxic activity of cisplatin involves both a nuclear and a cytoplasmic component. Despite the unresolved issues regarding its mechanism of action, the administration of cisplatin is generally associated with high rates of clinical responses. However, in the vast majority of cases, malignant cells exposed to cisplatin activate a multipronged adaptive response that renders them less susceptible to the antiproliferative and cytotoxic effects of the drug, and eventually resume proliferation. Thus, a large fraction of cisplatin-treated patients is destined to experience therapeutic failure and tumor recurrence. Throughout the last four decades great efforts have been devoted to the characterization of the molecular mechanisms whereby neoplastic cells progressively lose their sensitivity to cisplatin. The advent of high-content and high-throughput screening technologies has accelerated the discovery of cell-intrinsic and cell-extrinsic pathways that may be targeted to prevent or reverse cisplatin resistance in cancer patients. Still, the multifactorial and redundant nature of this phenomenon poses a significant barrier against the identification of effective chemosensitization strategies. Here, we discuss recent systems biology studies aimed at deconvoluting the complex circuitries that underpin cisplatin resistance, and how their findings might drive the development of rational approaches to tackle this clinically relevant problem.
588 citations
TL;DR: The existence of several “metabolic checkpoints” is proposed, refined molecular mechanisms that sense a panel of metabolic variables and emit one or more signals controlling cell fate, which might allow for the development of novel pharmacological approaches that block or stimulate cell death by inducing specific metabolic alterations.
Abstract: Beyond their contribution to basic metabolism, the major cellular organelles, in particular mitochondria, can determine whether cells respond to stress in an adaptive or suicidal manner. Thus, mitochondria can continuously adapt their shape to changing bioenergetic demands as they are subjected to quality control by autophagy, or they can undergo a lethal permeabilization process that initiates apoptosis. Along similar lines, multiple proteins involved in metabolic circuitries, including oxidative phosphorylation and transport of metabolites across membranes, may participate in the regulated or catastrophic dismantling of organelles. Many factors that were initially characterized as cell death regulators are now known to physically or functionally interact with metabolic enzymes. Thus, several metabolic cues regulate the propensity of cells to activate self-destructive programs, in part by acting on nutrient sensors. This suggests the existence of "metabolic checkpoints" that dictate cell fate in response to metabolic fluctuations. Here, we discuss recent insights into the intersection between metabolism and cell death regulation that have major implications for the comprehension and manipulation of unwarranted cell loss.
519 citations
TL;DR: It is shown that nutrient starvation causes rapid depletion of AcCoA, and multiple distinct manipulations designed to increase or reduce cytosolic Ac CoA led to the suppression or induction of autophagy, respectively, both in cultured human cells and in mice, delineating Ac coenzyme A-centered pharmacological strategies that allow for the therapeutic manipulation ofautophagy.
397 citations
French Institute of Health and Medical Research1, Katholieke Universiteit Leuven2, Ben-Gurion University of the Negev3, German Cancer Research Center4, Istituto Superiore di Sanità5, University of Turin6, Georgia Regents University7, University of Oxford8, Cardiff University9, Oregon Health & Science University10, Yale University11, Cold Spring Harbor Laboratory12, University of Pennsylvania13, University of Burgundy14, National Institutes of Health15, Georgetown University16, University of Miami17, Icahn School of Medicine at Mount Sinai18, GlaxoSmithKline19, Centre national de la recherche scientifique20, University of Paris21, Heidelberg University22, University of Pittsburgh23, Karolinska Institutet24, Hamad Medical Corporation25, University of Sheffield26, Centre Hospitalier Universitaire de Toulouse27, University of Lausanne28, University of Milan29, University of Navarra30, Leiden University31, University of Texas Health Science Center at Houston32, Istituto Giannina Gaslini33, Roswell Park Cancer Institute34, University of California, San Francisco35, Northwestern University36, Johns Hopkins University37, Thomas Jefferson University38, Main Line Health39, University of Buenos Aires40, Memorial Sloan Kettering Cancer Center41, University of Chicago42, Martin Luther University of Halle-Wittenberg43, Mie University44, University of Lisbon45, QIMR Berghofer Medical Research Institute46, University of Queensland47, Ludwig Institute for Cancer Research48, University of Connecticut49, University of Nebraska Medical Center50, Université catholique de Louvain51, Mayo Clinic52, Technische Universität München53, University of South Florida54, Cornell University55, University of Michigan56
TL;DR: A critical, integrated classification of anticancer immunotherapies is proposed and the clinical relevance of these approaches is discussed.
Abstract: During the past decades, anticancer immunotherapy has evolved from a promising therapeutic option to a robust clinical reality. Many immunotherapeutic regimens are now approved by the US Food and Drug Administration and the European Medicines Agency for use in cancer patients, and many others are being investigated as standalone therapeutic interventions or combined with conventional treatments in clinical studies. Immunotherapies may be subdivided into "passive" and "active" based on their ability to engage the host immune system against cancer. Since the anticancer activity of most passive immunotherapeutics (including tumor-targeting monoclonal antibodies) also relies on the host immune system, this classification does not properly reflect the complexity of the drug-host-tumor interaction. Alternatively, anticancer immunotherapeutics can be classified according to their antigen specificity. While some immunotherapies specifically target one (or a few) defined tumor-associated antigen(s), others operate in a relatively non-specific manner and boost natural or therapy-elicited anticancer immune responses of unknown and often broad specificity. Here, we propose a critical, integrated classification of anticancer immunotherapies and discuss the clinical relevance of these approaches.
375 citations
TL;DR: Tissue-specific inactivation of Atg5, essential for the formation of autophagosomes, markedly impairs the progression of KRas(G12D)-driven lung cancer, resulting in a significant survival advantage of tumour-bearing mice, suggesting a link between deregulated autophagy and regulatory T cell controlled anticancer immunity.
Abstract: Autophagy prolongs the survival of cells in stressful conditions but its role in cancer is unclear. Here, Rao et al. show that loss of the autophagic protein Atg5 enhanced cancer incidence but impaired tumour progression in a mouse model of lung cancer.
369 citations
TL;DR: It is shown that caspase- and PANX1-dependent lysosomal exocytosis has an essential role in ATP release as triggered by immunogenic chemotherapy, and suggests that autophagy-deficient cancer cells fail to elicit therapy-relevant immune responses in vivo.
Abstract: The immunogenic demise of cancer cells can be induced by various chemotherapeutics, such as anthracyclines and oxaliplatin, and provokes an immune response against tumor-associated antigens. Thus, immunogenic cell death (ICD)-inducing antineoplastic agents stimulate a tumor-specific immune response that determines the long-term success of therapy. The release of ATP from dying cells constitutes one of the three major hallmarks of ICD and occurs independently of the two others, namely, the pre-apoptotic exposure of calreticulin on the cell surface and the postmortem release of high-mobility group box 1 (HMBG1) into the extracellular space. Pre-mortem autophagy is known to be required for the ICD-associated secretion of ATP, implying that autophagy-deficient cancer cells fail to elicit therapy-relevant immune responses in vivo. However, the precise molecular mechanisms whereby ATP is actively secreted in the course of ICD remain elusive. Using a combination of pharmacological screens, silencing experiments and techniques to monitor the subcellular localization of ATP, we show here that, in response to ICD inducers, ATP redistributes from lysosomes to autolysosomes and is secreted by a mechanism that requires the lysosomal protein LAMP1, which translocates to the plasma membrane in a strictly caspase-dependent manner. The secretion of ATP additionally involves the caspase-dependent activation of Rho-associated, coiled-coil containing protein kinase 1 (ROCK1)-mediated, myosin II-dependent cellular blebbing, as well as the opening of pannexin 1 (PANX1) channels, which is also triggered by caspases. Of note, although autophagy and LAMP1 fail to influence PANX1 channel opening, PANX1 is required for the ICD-associated translocation of LAMP1 to the plasma membrane. Altogether, these findings suggest that caspase- and PANX1-dependent lysosomal exocytosis has an essential role in ATP release as triggered by immunogenic chemotherapy.
367 citations
TL;DR: The preclinical and clinical studies testing the antineoplastic activity of IDO1-targeting interventions are summarized.
Abstract: Indoleamine 2,3-dioxigenase 1 (IDO1) is the main enzyme that catalyzes the first, rate-limiting step of the so-called “kynurenine pathway”, i.e., the metabolic cascade that converts the essential amino acid L-tryptophan (Trp) into L-kynurenine (Kyn). IDO1, which is expressed constitutively by some tissues and in an inducible manner by specific subsets of antigen-presenting cells, has been shown to play a role in the establishment and maintenance of peripheral tolerance. At least in part, this reflects the capacity of IDO1 to restrict the microenvironmental availability of Trp and to favor the accumulation of Kyn and some of its derivatives. Also, several neoplastic lesions express IDO1, providing them with a means to evade anticancer immunosurveillance. This consideration has driven the development of several IDO1 inhibitors, some of which (including 1-methyltryptophan) have nowadays entered clinical evaluation. In animal tumor models, the inhibition of IDO1 by chemical or genetic interventions is indeed associated with the (re)activation of therapeutically relevant anticancer immune responses. This said, several immunotherapeutic regimens exert robust clinical activity in spite of their ability to promote the expression of IDO1. Moreover, 1-methyltryptophan has recently been shown to exert IDO1-independent immunostimulatory effects. Here, we summarize the preclinical and clinical studies testing the antineoplastic activity of IDO1-targeting interventions.
TL;DR: It is shown that nucleocytosolic acetyl-coenzyme A (AcCoA) production is a metabolic repressor of autophagy during aging in yeast, and brain-specific knockdown of Drosophila AcCoA synthetase was sufficient to enhance autophagic protein clearance and prolong lifespan.
TL;DR: The signaling pathways, pathophysiological relevance and therapeutic implications of the major molecular cascades that underlie RN are reviewed, highlighting the degree of interconnectivity that characterizes RN.
TL;DR: The mechanisms whereby cellular compartments sense homeostatic perturbations and translate them into a cell-death-initiating signal are discussed, which can respond to stress by attemptinwg to recover homeostasis or by activating molecular cascades that lead to cell death by apoptosis or necrosis.
Abstract: In a majority of pathophysiological settings, cell death is not accidental — it is controlled by a complex molecular apparatus. Such a system operates like a computer: it receives several inputs that inform on the current state of the cell and the extracellular microenvironment, integrates them and generates an output. Thus, depending on a network of signals generated at specific subcellular sites, cells can respond to stress by attemptinwg to recover homeostasis or by activating molecular cascades that lead to cell death by apoptosis or necrosis. Here, we discuss the mechanisms whereby cellular compartments — including the nucleus, mitochondria, plasma membrane, endoplasmic reticulum, Golgi apparatus, lysosomes, cytoskeleton and cytosol — sense homeostatic perturbations and translate them into a cell-death-initiating signal.
TL;DR: A unifying definition of CRMs is proposed as compounds that stimulate autophagy by favouring the deacetylation of cellular proteins in order to have health-promoting and lifespan-extending effects.
Abstract: Caloric restriction, be it constant or intermittent, is reputed to have health-promoting and lifespan-extending effects. Caloric restriction mimetics (CRMs) are compounds that mimic the biochemical and functional effects of caloric restriction. In this Opinion article, we propose a unifying definition of CRMs as compounds that stimulate autophagy by favouring the deacetylation of cellular proteins. This deacetylation process can be achieved by three classes of compounds that deplete acetyl coenzyme A (AcCoA; the sole donor of acetyl groups), that inhibit acetyl transferases (a group of enzymes that acetylate lysine residues in an array of proteins) or that stimulate the activity of deacetylases and hence reverse the action of acetyl transferases. A unifying definition of CRMs will be important for the continued development of this class of therapeutic agents.
TL;DR: It is reported that methionine restriction (MetR) extends yeast chronological lifespan in an autophagy-dependent manner and requires the subsequent stimulation of vacuolar acidification, while it is epistatic to the equally autophagic-dependent anti-aging pathway triggered by TOR1 inhibition or deletion.
Abstract: Reduced supply of the amino acid methionine increases longevity across species through an as yet elusive mechanism. Here, we report that methionine restriction (MetR) extends yeast chronological lifespan in an autophagy-dependent manner. Single deletion of several genes essential for autophagy (ATG5, ATG7 or ATG8) fully abolished the longevity-enhancing capacity of MetR. While pharmacological or genetic inhibition of TOR1 increased lifespan in methionine-prototroph yeast, TOR1 suppression failed to extend the longevity of methionine-restricted yeast cells. Notably, vacuole-acidity was specifically enhanced by MetR, a phenotype that essentially required autophagy. Overexpression of vacuolar ATPase components (Vma1p or Vph2p) suffices to increase chronological lifespan of methionine-prototrophic yeast. In contrast, lifespan extension upon MetR was prevented by inhibition of vacuolar acidity upon disruption of the vacuolar ATPase. In conclusion, autophagy promotes lifespan extension upon MetR and requires the subsequent stimulation of vacuolar acidification, while it is epistatic to the equally autophagy-dependent anti-aging pathway triggered by TOR1 inhibition or deletion.
TL;DR: The results reveal that beyond its cytoprotective function, autophagy confers immunogenic properties to tumours, hence amplifying the efficacy of radiotherapy in an immunocompetent context, and has far-reaching implications for the development of pharmacological radiosensitizers.
Abstract: Clinical oncology heavily relies on the use of radiotherapy, which often leads to merely transient responses that are followed by local or distant relapse. The molecular mechanisms explaining radioresistance are largely elusive. Here, we identified a dual role of autophagy in the response of cancer cells to ionizing radiation. On one hand, we observed that the depletion of essential autophagy-relevant gene products, such as ATG5 and Beclin 1, increased the sensitivity of human or mouse cancer cell lines to irradiation, both in vitro (where autophagy inhibition increased radiation-induced cell death and decreased clonogenic survival) and in vivo, after transplantation of the cell lines into immunodeficient mice (where autophagy inhibition potentiated the tumour growth-inhibitory effect of radiotherapy). On the other hand, when tumour proficient or deficient for autophagy were implanted in immunocompetent mice, it turned out that defective autophagy reduced the efficacy of radiotherapy. Indeed, radiotherapy elicited an anti-cancer immune response that was dependent on autophagy-induced ATP release from stressed or dying tumour cells and was characterized by dense lymphocyte infiltration of the tumour bed. Intratumoural injection of an ecto-ATPase inhibitor restored the immune infiltration of autophagy-deficient tumours post radiotherapy and improved the growth-inhibitory effect of ionizing irradiation. Altogether, our results reveal that beyond its cytoprotective function, autophagy confers immunogenic properties to tumours, hence amplifying the efficacy of radiotherapy in an immunocompetent context. This has far-reaching implications for the development of pharmacological radiosensitizers.
TL;DR: It is shown that transplantable tumors exhibiting weak expression of nuclear HMGB1 respond to chemotherapy more effectively if the treatment is combined with the local or systemic administration of a highly purified and physiochemically defined and standardized lipopolysaccharide solution, which acts as a high-potency and exclusive TLR4 agonist, called Dendrophilin (DEN).
Abstract: Immunogenic cell death induced by anticancer chemotherapy is characterized by a series of molecular hallmarks that include the exodus of high-mobility group box 1 protein (HMGB1) from dying cells. HMGB1 is a nuclear nonhistone chromatin-binding protein. It is secreted at the late stages of cellular demise and engages Toll-like receptor4 (TLR4) on dendritic cells (DCs) to accelerate the processing of phagocytic cargo in the DC and to facilitate antigen presentation by DC to T cells. The absence of HMGB1 expression by dying tumor cells exposed to anthracyclines or oxaliplatin compromises DC-dependent T-cell priming by tumor-associated antigens. Here, we show that transplantable tumors exhibiting weak expression of nuclear HMGB1 respond to chemotherapy more effectively if the treatment is combined with the local or systemic administration of a highly purified and physiochemically defined and standardized lipopolysaccharide solution, which acts as a high-potency and exclusive TLR4 agonist, called Dendrophilin (DEN). The synergistic antitumor effects mediated by the combination of chemotherapy and immunotherapy relied upon the presence of the MyD88 (myeloid differentiation primary response gene) adapter of TLR4 (but not that of the TIR-domain-containing adapter-inducing interferon-β adapter), in line with the well-characterized action of DEN on the MyD88 signaling pathway. DEN and anthracyclines synergized to induce intratumoral accumulation of interferon-γ-producing CD4+ and CD8+ T lymphocytes. Moreover, DEN could restore the immunogenicity of dying tumor cells from which HMGB1 had been depleted by RNA interference. These findings underscore the potential clinical utility of combination regimens involving immunogenic chemotherapy and certain TLR4 agonists in advanced HMGB1-deficient cancers.
TL;DR: The dual role of autophagy in oncogenesis and tumor progression is discussed, and the results or design of clinical studies recently completed or initiated to evaluate the therapeutic activity of chloroquine derivatives in cancer patients are summarized.
Abstract: Macroautophagy (herein referred to as autophagy) is a highly conserved mechanism for the lysosomal degradation of cytoplasmic components. Autophagy is critical for the maintenance of intracellular homeostasis, both in baseline conditions and in the context of adaptive responses to stress. In line with this notion, defects in the autophagic machinery have been etiologically associated with various human disorders including infectious, inflammatory and neoplastic conditions. Once tumors are established, however, autophagy sustains the survival of malignant cells, hence representing an appealing target for the design of novel anticancer regimens. Accordingly, inhibitors of autophagy including chloroquine and hydroxychloroquine have been shown to mediate substantial antineoplastic effects in preclinical models, especially when combined with chemo- or radiotherapeutic interventions. The pharmacological profile of chloroquine and hydroxychloroquine, however, appear to involve mechanisms other than autophagy inhibition. Here, we discuss the dual role of autophagy in oncogenesis and tumor progression, and summarize the results or design of clinical studies recently completed or initiated to evaluate the therapeutic activity of chloroquine derivatives in cancer patients.
TL;DR: It is reported that oral treatment with cysteamine greatly reduces the mortality rate and improves the phenotype of newborn mice bearing the F508del-CFTR mutation, and optimal schedules of cysteamines plus EGCG might be used for the treatment of CF caused by the F504del- CFTR mutation.
Abstract: Restoration of BECN1/Beclin 1-dependent autophagy and depletion of SQSTM1/p62 by genetic manipulation or autophagy-stimulatory proteostasis regulators, such as cystamine, have positive effects on mouse models of human cystic fibrosis (CF). These measures rescue the functional expression of the most frequent pathogenic CFTR mutant, F508del, at the respiratory epithelial surface and reduce lung inflammation in CftrF508del homozygous mice. Cysteamine, the reduced form of cystamine, is an FDA-approved drug. Here, we report that oral treatment with cysteamine greatly reduces the mortality rate and improves the phenotype of newborn mice bearing the F508del-CFTR mutation. Cysteamine was also able to increase the plasma membrane expression of the F508del-CFTR protein in nasal epithelial cells from F508del homozygous CF patients, and these effects persisted for 24 h after cysteamine withdrawal. Importantly, this cysteamine effect after washout was further sustained by the sequential administration of epigallocatec...
TL;DR: It is demonstrated that CDDP-resistant non-small lung cancer cells undergo profound remodeling of their endoplasmic reticulum (ER) proteome and exhibit a dramatic overexpression of two protein disulfide isomerases, PDIA4 and PDIA6, without any alteration in ER-cytosol Ca2+ fluxes.
Abstract: Intrinsic and acquired chemoresistance are frequent causes of cancer eradication failure. Thus, long-term cis-diaminedichloroplatine(II) (CDDP) or cisplatin treatment is known to promote tumor cell resistance to apoptosis induction via multiple mechanisms involving gene expression modulation of oncogenes, tumor suppressors and blockade of pro-apoptotic mitochondrial membrane permeabilization. Here, we demonstrate that CDDP-resistant non-small lung cancer cells undergo profound remodeling of their endoplasmic reticulum (ER) proteome (>80 proteins identified by proteomics) and exhibit a dramatic overexpression of two protein disulfide isomerases, PDIA4 and PDIA6, without any alteration in ER-cytosol Ca(2+) fluxes. Using pharmacological and genetic inhibition, we show that inactivation of both proteins directly stimulates CDDP-induced cell death by different cellular signaling pathways. PDIA4 inactivation restores a classical mitochondrial apoptosis pathway, while knockdown of PDIA6 favors a non-canonical cell death pathway sharing some necroptosis features. Overexpression of both proteins has also been found in lung adenocarcinoma patients, suggesting a clinical importance of these proteins in chemoresistance.
TL;DR: It is shown that anthracycline-based chemotherapy promotes the recruitment of functional CD11b(+)CD11c(+)Ly6C(high)Ly6G(-)MHCII(+) dendritic cell-like antigen-presenting cells (APC) into the tumor bed, but not into lymphoid organs.
Abstract: The therapeutic efficacy of anthracyclines relies, at least partially, on the induction of a dendritic cell- and T-lymphocyte-dependent anticancer immune response. Here, we show that anthracycline-based chemotherapy promotes the recruitment of functional CD11b(+)CD11c(+)Ly6C(high)Ly6G(-)MHCII(+) dendritic cell-like antigen-presenting cells (APC) into the tumor bed, but not into lymphoid organs. Accordingly, draining lymph nodes turned out to be dispensable for the proliferation of tumor antigen-specific T cells within neoplastic lesions as induced by anthracyclines. In addition, we found that tumors treated with anthracyclines manifest increased expression levels of the chemokine Ccl2. Such a response is important as neoplasms growing in Ccl2(-/-) mice failed to accumulate dendritic cell-like APCs in response to chemotherapy. Moreover, cancers developing in mice lacking Ccl2 or its receptor (Ccr2) exhibited suboptimal therapeutic responses to anthracycline-based chemotherapy. Altogether, our results underscore the importance of the CCL2/CCR2 signaling axis for therapeutic anticancer immune responses as elicited by immunogenic chemotherapy.
TL;DR: Administration of the naturally occurring polyamine spermidine alleviates a series of PD-related degenerative processes in the fruit fly Drosophila melanogaster and the nematode Caenorhabditis elegans, two established model systems for PD pathology.
Abstract: As our society ages, neurodegenerative disorders like Parkinson`s disease (PD) are increasing in pandemic proportions. While mechanistic understanding of PD is advancing, a treatment with well tolerable drugs is still elusive. Here, we show that administration of the naturally occurring polyamine spermidine, which declines continuously during aging in various species, alleviates a series of PD-related degenerative processes in the fruit fly Drosophila melanogaster and the nematode Caenorhabditis elegans, two established model systems for PD pathology. In the fruit fly, simple feeding with spermidine inhibited loss of climbing activity and early organismal death upon heterologous expression of human α-synuclein, which is thought to be the principal toxic trigger of PD. In this line, administration of spermidine rescued α-synuclein-induced loss of dopaminergic neurons, a hallmark of PD, in nematodes. Alleviation of PD-related neurodegeneration by spermidine was accompanied by induction of autophagy, suggest...
TL;DR: Clinical trials that have been launched in the last 14 months to assess the therapeutic profile of immunostimulatory mAbs and discuss clinical trials that are underway to test the therapeutic potential of OX40- and GITR-activating mAbs are discussed.
Abstract: Immunostimulatory monoclonal antibodies (mAbs) exert antineoplastic effects by eliciting a novel or reinstating a pre-existing antitumor immune response. Most often, immunostimulatory mAbs activate T lymphocytes or natural killer (NK) cells by inhibiting immunosuppressive receptors, such as cytotoxic T lymphocyte-associated protein 4 (CTLA4) or programmed cell death 1 (PDCD1, best known as PD-1), or by engaging co-stimulatory receptors, like CD40, tumor necrosis factor receptor superfamily, member 4 (TNFRSF4, best known as OX40) or TNFRSF18 (best known as GITR). The CTLA4-targeting mAb ipilimumab has been approved by the US Food and Drug Administration for use in patients with unresectable or metastatic melanoma in 2011. The therapeutic profile of ipilimumab other CTLA4-blocking mAbs, such as tremelimumab, is currently being assessed in subjects affected by a large panel of solid neoplasms. In the last few years, promising clinical results have also been obtained with nivolumab, a PD-1-targeting mAb formerly known as BMS-936558. Accordingly, the safety and efficacy of nivolumab and other PD-1-blocking molecules are being actively investigated. Finally, various clinical trials are underway to test the therapeutic potential of OX40- and GITR-activating mAbs. Here, we summarize recent findings on the therapeutic profile of immunostimulatory mAbs and discuss clinical trials that have been launched in the last 14 months to assess the therapeutic profile of these immunotherapeutic agents.
TL;DR: Results underscore the suitability of the high-throughput screening system described here for the identification of novel ICD inducers and pointed to septacidin, an antibiotic produced by Streptomyces fibriatus, as a novel putative inducer of ICD.
Abstract: Immunogenic cell death (ICD) inducers can be defined as agents that exert cytotoxic effects while stimulating an immune response against dead cell-associated antigens. When initiated by anthracyclines, ICD is accompanied by stereotyped molecular changes, including the pre-apoptotic exposure of calreticulin (CRT) on the cell surface, the lysosomal secretion of ATP during the blebbing phase of apoptosis, and the release of high mobility group box 1 (HMGB1) from dead cells. By means of genetically engineered human osteosarcoma U2OS cells, we screened the 879 anticancer compounds of the National Cancer Institute (NCI) Mechanistic Diversity Set for their ability to promote all these hallmarks of ICD in vitro. In line with previous findings from our group, several cardiac glycosides exhibit a robust propensity to elicit the major manifestations of ICD in cultured neoplastic cells. This screen pointed to septacidin, an antibiotic produced by Streptomyces fibriatus, as a novel putative inducer of ICD. In low-throughput validation experiments, septacidin promoted CRT exposure, ATP secretion and HGMB1 release from both U2OS cells and murine fibrosarcoma MCA205 cells. Moreover, septacidin-killed MCA205 cells protected immunocompetent mice against a re-challenge with living cancer cells of the same type. Finally, the antineoplastic effects of septacidin on established murine tumors were entirely dependent on T lymphocytes. Altogether, these results underscore the suitability of the high-throughput screening system described here for the identification of novel ICD inducers.
TL;DR: It is surmised that the identification of patients that are likely to benefit from PARP inhibition will improve the clinical use of PARP inhibitors in a defined target population, and special emphasis is placed on biomarker discovery.
Abstract: Poly(ADP-ribose) polymerase (PARP) inhibitors have raised high expectations for the treatment of multiple malignancies. PARP inhibitors, which can be used as monotherapies or in combination with DNA-damaging agents, are particularly efficient against tumors with defects in DNA repair mechanisms, in particular the homologous recombination pathway, for instance due to BRCA mutations. Thus, deficient DNA repair provides a framework for the success of PARP inhibitors in medical oncology. Here, we review encouraging results obtained in recent clinical trials investigating the safety and efficacy of PARP inhibitors as anticancer agents. We discuss emerging mechanisms of regulation of homologous recombination and how inhibition of DNA repair might be used in cancer therapy. We surmise that the identification of patients that are likely to benefit from PARP inhibition will improve the clinical use of PARP inhibitors in a defined target population. Thus, we will place special emphasis on biomarker discovery.
TL;DR: The data support a dual role of BECN1 in ALS and depict a complex scenario in terms of predicting the effects of manipulating autophagy in a disease context.
Abstract: Pharmacological activation of autophagy is becoming an attractive strategy to induce the selective degradation of aggregate-prone proteins. Recent evidence also suggests that autophagy impairment may underlie the pathogenesis of several neurodegenerative diseases. Mutations in the gene encoding SOD1 (superoxide disumutase 1) trigger familial amyotrophic lateral sclerosis (ALS), inducing its misfolding and aggregation and the progressive loss of motoneurons. It is still under debate whether autophagy has a protective or detrimental role in ALS. Here we evaluate the impact of BECN1/Beclin 1, an essential autophagy regulator, in ALS. BECN1 levels were upregulated in both cells and animals expressing mutant SOD1. To evaluate the impact of BECN1 to the pathogenesis of ALS in vivo, we generated mutant SOD1 transgenic mice heterozygous for Becn1. We observed an unexpected increase in life span of mutant SOD1 transgenic mice haploinsufficient for Becn1 compared with littermate control animals. These effects were accompanied by enhanced accumulation of SQSTM1/p62 and reduced levels of LC3-II, and an altered equilibrium between monomeric and oligomeric mutant SOD1 species in the spinal cord. At the molecular level, we detected an abnormal interaction of mutant SOD1 with the BECN1-BCL2L1 complex that may impact autophagy stimulation. Our data support a dual role of BECN1 in ALS and depict a complex scenario in terms of predicting the effects of manipulating autophagy in a disease context.
TL;DR: It is speculated that CRM may mediate their broad health-improving effects by triggering the same molecular pathways that usually are elicited by long-term caloric restriction or short-term starvation and that imply the induction of autophagy as an obligatory event conferring organismal, organ- or cytoprotection.
Abstract: Nutrient depletion, which is one of the physiological triggers of autophagy, results in the depletion of intracellular acetyl coenzyme A (AcCoA) coupled to the deacetylation of cellular proteins. We surmise that there are 3 possibilities to mimic these effects, namely (i) the depletion of cytosolic AcCoA by interfering with its biosynthesis, (ii) the inhibition of acetyltransferases, which are enzymes that transfer acetyl groups from AcCoA to other molecules, mostly leucine residues in cellular proteins, or (iii) the stimulation of deacetylases, which catalyze the removal of acetyl groups from leucine residues. There are several examples of rather nontoxic natural compounds that act as AcCoA depleting agents (e.g., hydroxycitrate), acetyltransferase inhibitors (e.g., anacardic acid, curcumin, epigallocatechin-3-gallate, garcinol, spermidine) or deacetylase activators (e.g., nicotinamide, resveratrol), and that are highly efficient inducers of autophagy in vitro and in vivo, in rodents. Another common characteristic of these agents is their capacity to reduce aging-associated diseases and to confer protective responses against ischemia-induced organ damage. Hence, we classify them as "caloric restriction mimetics" (CRM). Here, we speculate that CRM may mediate their broad health-improving effects by triggering the same molecular pathways that usually are elicited by long-term caloric restriction or short-term starvation and that imply the induction of autophagy as an obligatory event conferring organismal, organ- or cytoprotection.
TL;DR: A novel role for dexamethasone-induced autophagy/mitophagy in the regulation of the muscle atrophy program is suggested.
Abstract: Glucocorticoids, such as dexamethasone, enhance protein breakdown via ubiquitin-proteasome system. However, the role of autophagy in organelle and protein turnover in the glucocorticoid-dependent atrophy program remains unknown. Here, we show that dexamethasone stimulates an early activation of autophagy in L6 myotubes depending on protein kinase, AMPK, and glucocorticoid receptor activity. Dexamethasone increases expression of several autophagy genes, including ATG5, LC3, BECN1, and SQSTM1 and triggers AMPK-dependent mitochondrial fragmentation associated with increased DNM1L protein levels. This process is required for mitophagy induced by dexamethasone. Inhibition of mitochondrial fragmentation by Mdivi-1 results in disrupted dexamethasone-induced autophagy/mitophagy. Furthermore, Mdivi-1 increases the expression of genes associated with the atrophy program, suggesting that mitophagy may serve as part of the quality control process in dexamethasone-treated L6 myotubes. Collectively, these data suggest a novel role for dexamethasone-induced autophagy/mitophagy in the regulation of the muscle atrophy program.
TL;DR: It is shown that pheromones can act as physiological inducers of CRT Exposure in yeast cells, thereby facilitating the formation of mating conjugates, and that a large-spectrum inhibitor of G protein-coupled receptors prevents CRT exposure in human cancer cells exposed to MTX.
Abstract: The exposure of calreticulin (CRT) on the surface of stressed and dying cancer cells facilitates their uptake by dendritic cells and the subsequent presentation of tumor-associated antigens to T lymphocytes, hence stimulating an anticancer immune response. The chemotherapeutic agent mitoxantrone (MTX) can stimulate the peripheral relocation of CRT in both human and yeast cells, suggesting that the CRT exposure pathway is phylogenetically conserved. Here, we show that pheromones can act as physiological inducers of CRT exposure in yeast cells, thereby facilitating the formation of mating conjugates, and that a large-spectrum inhibitor of G protein-coupled receptors (which resemble the yeast pheromone receptor) prevents CRT exposure in human cancer cells exposed to MTX. An RNA interference screen as well as transcriptome analyses revealed that chemokines, in particular human CXCL8 (best known as interleukin-8) and its mouse ortholog Cxcl2, are involved in the immunogenic translocation of CRT to the outer leaflet of the plasma membrane. MTX stimulated the production of CXCL8 by human cancer cells in vitro and that of Cxcl2 by murine tumors in vivo. The knockdown of CXCL8/Cxcl2 receptors (CXCR1/Cxcr1 and Cxcr2) reduced MTX-induced CRT exposure in both human and murine cancer cells, as well as the capacity of the latter-on exposure to MTX-to elicit an anticancer immune response in vivo. Conversely, the addition of exogenous Cxcl2 increased the immunogenicity of dying cells in a CRT-dependent manner. Altogether, these results identify autocrine and paracrine chemokine signaling circuitries that modulate CRT exposure and the immunogenicity of cell death.