Patent Application
20160113958
The present invention provides for a compound capable of modulating (a) the biological activity of ADP-dependent glucokinase (ADPGK) and/or glycerol-3-phosphate dehydrogenase (GPD2) or (b) the expression of the gene encoding ADPGK or GPD2 for use in treating a disease (a) associated with aberrant cell proliferation, e.g., a neoplasm, or (b) of the immune system, e.g., an autoimmune disease or Graft-versus-Host-Disease (GvHD).
Despite enormous investments of financial and human resources, cancer remains one of the major causes of death. Many management options for cancer exist including: chemotherapy, radiation therapy, surgery, monoclonal antibody therapy and other methods. Which treatments are used depends upon the type of cancer, the location and grade of the tumor, and the stage of the disease, as well as the general state of a person's health. Complete removal of the cancer without damage to the rest of the body is the goal of treatment for most cancers. Sometimes this can be accomplished by surgery, but the propensity of cancers to invade adjacent tissue or to spread to distant sites by microscopic metastasis often limits its effectiveness. Surgery often required the removal of a wide surgical margin or a free margin. The width of the free margin depends on the type of the cancer, the method of removal (CCPDMA, Mohs surgery, POMA, etc.). The margin can be as little as 1 mm for basal cell cancer using CCPDMA or Mohs surgery, to several centimeters for aggressive cancers. The effectiveness of chemotherapy is often limited by toxicity to other tissues in the body. Radiation can also cause damage to normal tissue. Because cancer is a class of diseases, it is unlikely that there will ever be a single “cure for cancer” any more than there will be a single treatment for all infectious diseases. Angiogenesis inhibitors were once thought to have potential as a “silver bullet” treatment applicable to many types of cancer, but this has not been the case in practice.
Immunotherapy of cancer has also been described in the art for a number of approaches, including early attempts of cell-based cancer vaccines consisting of killed autologous tumor cells or tumor cell lysates mixed with adjuvants, such as Bacillus Calmette Guerin (BCG) and Corynebacterium parvum, in an attempt to amplify tumor-specific immune responses. Further immunotherapeutic strategies include gene therapy, administration of small molecular inhibitors and activators, anti-sense oligonucleotides, vaccines, activated autologous cells, antibodies, as well as cytokines and chemokines, natural or recombinant proteins, autologous cells modified in vitro.
Citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention.
In one embodiment of the invention, provided is a compound capable of modulating (a) the biological activity of glycerol-3-phosphate dehydrogenase (GPD2) and/or ADP-dependent glucokinase (ADPGK) or (b) the expression of the gene encoding GPD2 or ADPGK for use in treating a disease (a) associated with aberrant cell proliferation or (b) of the immune system.
Also provided as a further embodiment is a method for identifying a compound capable of modulating the biological activity of GPD2 or ADPGK or the expression of the gene encoding GPD2 or ADPG, comprising the steps of:
In an additional embodiment, provided is a method of selecting a therapy modality for a patient afflicted with a disease as characterized in claim 1, comprising
Accordingly, it is an object of the invention to not encompass within the invention any previously known product, process of making the product, or method of using the product such that Applicants reserve the right and hereby disclose a disclaimer of any previously known product, process, or method. It is further noted that the invention does not intend to encompass within the scope of the invention any product, process, or making of the product or method of using the product, which does not meet the written description and enablement requirements of the USPTO (35 U.S.C. §112, first paragraph) or the EPO (Article 83 of the EPC), such that Applicants reserve the right and hereby disclose a disclaimer of any previously described product, process of making the product, or method of using the product.
It is noted that in this disclosure and particularly in the claims and/or paragraphs, terms such as “comprises”, “comprised”, “comprising” and the like can have the meaning attributed to it in U.S. Patent law; e.g., they can mean “includes”, “included”, “including”, and the like; and that terms such as “consisting essentially of” and “consists essentially of” have the meaning ascribed to them in U.S. Patent law, e.g., they allow for elements not explicitly recited, but exclude elements that are found in the prior art or that affect a basic or novel characteristic of the invention.
These and other embodiments are disclosed or are obvious from and encompassed by, the following Detailed Description.
The following detailed description, given by way of example, but not intended to limit the invention solely to the specific embodiments described, may best be understood in conjunction with the accompanying drawings.
In spite of the length of time that these therapies have been investigated, there remains a need for improved strategies for tumor therapy as well as therapy of immune diseases. It is, thus, the object of the present invention to provide a safe and effective means for such therapies.
According to the invention this is achieved by the subject matters defined in the claims. Activation via the T cell receptor (TCR) drives T cells into rapid proliferation and differentiation. At the stage of PLCγ1 induction, the TCR response splits into two pathways. Inositol 3,4,5-triphosphate induces a rise in intracellular Ca2+ concentration and activation of Ca2+-dependent transcription factors, e.g. NF-AT. Diacylglycerol (DAG) activates PKCθ and RasGRP proteins leading to triggering of NF-KB and AP-1. These three transcription factors essentially control T cell activation-induced gene expression. Thus, simultaneous treatment with Ca2+ ionophore, e.g. ionomycin (Iono), and a DAG mimetic, phorbol 12-myristate 13-acetate (PMA), yields full T cell activation-driven transcriptional response. It has been shown that T cell activation is paralleled by transient generation of low, physiologically relevant levels of ROS, i.e. a H2O2-mediated oxidative signal, which facilitates activation of oxidation-dependent transcription factors, NF-κB and AP-1 (1, 2). The oxidative signal is indispensible for T cell activation. Together with Ca2+ influx, it constitutes a minimal requirement for T cell activation-induced gene expression (e.g. IL-2, IL-4, CD95L). Neither signal is sufficient by itself (1, 3, 4).
Several different enzymatic sources, such as the mitochondrial respiratory chain, lipooxygenases and NADPH oxidases, NOX2 and DUOX2, were described to participate in T cell activation-triggered ROS production (1, 3, 5-8). Previous work demonstrates a crucial role for mitochondria as the source of the oxidative signal. Using a variety of experimental approaches, it could be shown that TCR proximal signalosome-mediated PKCθ activation drives ROS production from mitochondrial respiratory complex I. In addition, generation of the oxidative signal was shown to be blocked by metformin, an anti-diabetic drug (3).
T cell activation-induced gene expression depends on glucose uptake (9, 10).
Furthermore, T cell activation is accompanied by a metabolic switch from mitochondrial ATP production to aerobic glycolysis, i.e. the Warburg effect (11-13), a phenomenon also characteristic for fast proliferating cancer cells (11, 14). In addition, cancer cells are often endowed with high intrinsic ROS production and constitutive activation of the NF-κB pathway (15-18). Interestingly, an up-regulated glucose metabolism under hyperglycemic and hypoxic conditions was shown to induce mitochondrial ROS release in different cellular systems (18-21). These findings show that upon T cell activation the mitochondrial respiratory chain switches from an ATP producing to a signaling machinery.
During the experiments resulting in the present invention the metabolic changes accompanying the generation of the oxidative signal (i.e. occurring within 1 h upon TCR or PMA triggering (1, 3)) in partially glycolytic proliferating cells—in vitro expanded peripheral human T cells (13, 22) and Jurkat T cells (23)—was studied. It could be shown that TCR-triggered activation of ADP-dependent glucokinase (ADPGK), an alternative, typically archaeal glycolytic enzyme, mediates the generation of the oxidative signal. ADPGK-driven increase in glycolytic flux coincides with TCR-induced glucose uptake, down-regulation of mitochondrial respiration and deviation of glycolysis towards mitochondrial glycerol-3-phosphate (GPD) shuttle, i.e. a Warburg metabolic shift. The activation of respiratory chain-associated GPD2 results in hyper-reduction of ubiquinone and ROS release from mitochondrial complex I. In parallel, mitochondrial bioenergetics and ultrastructure are altered. Since the oxidative signal drives NF-KB-mediated gene expression, downregulation of ADPGK and GPD2 inhibits NF-KB induction, while ADPGK over-expression potentiates it. Interestingly, an enhanced expression of ADPGK and GPD2 in chronic lymphocytic leukemia (CLL) cells suggests a tumorigenic function. The described novel signaling and metabolic pathway may have profound meaning for tumorgenesis and may provide new means for therapy.
Thus, the present invention relates to a compound capable of modulating (a) the biological activity of ADP-dependent glucokinase (ADPGK) and/or glycerol-3-phosphate dehydrogenase (GPD2) or (b) the expression of the gene encoding ADPGK or GPD2 for use in treating a disease (a) associated with aberrant cell proliferation or (b) of the immune system.
The modulation, e.g, reduction or inhibition of the biological activity can be effected by direct interaction or binding of a compound to ADPGK and GPD2, respectively, or by indirect interaction, e.g., by interacting with a compound that is associated with the biological activity of ADPGK or GPD2. The reduction or inhibition of the biological activity can also be achieved by the application of altered, e.g., inactive forms of ADPGK or GPD2, preferably in excess.
Examples of suitable compounds reducing or inhibiting the biological activity of ADPGK or GPD2, e.g., immune suppressive modulators, or the expression of the corresponding gene with the aim to get a therapeutic effect are:
Further compounds suitable for the purposes of the present invention and methods how to identify/select such compounds are in more detail described below.
Preferably, in a pharmaceutical composition, such compounds as described above and below are combined with a pharmaceutically acceptable carrier. “Pharmaceutically acceptable” is meant to encompass any carrier, which does not interfere with the effectiveness of the biological activity of the active ingredient and that is not toxic to the patient to which it is administered. Examples of suitable pharmaceutical carriers are well known in the art and include phosphate buffered saline solutions, water, emulsions, such as oil/water emulsions, various types of wetting agents, sterile solutions etc. Such carriers can be formulated by conventional methods and the active compound can be administered to the subject at an effective dose.
An “effective dose” refers to an amount of the active ingredient that is sufficient to affect the course and the severity of the disease, e.g., neoplasia, leading to the reduction or remission of such a pathology. An “effective dose” useful for treatment may be determined using methods known to one skilled in the art.
Administration of the suitable compositions may be effected by different ways, e.g. by intravenous, intraperitoneal, subcutaneous, intramuscular, topical or intradermal administration. The route of administration, of course, depends on the kind of therapy and the kind of compound contained in the pharmaceutical composition. The dosage regimen will be determined by the attending physician and other clinical factors. As is well known in the medical arts, dosages for any one patient depends on many factors, including the patient's size, body surface area, age, sex, the particular compound to be administered, time and route of administration, the kind of therapy, general health and other drugs being administered concurrently.
The person skilled in the art can easily identify or generate compounds useful for the treatments of the present invention based on the knowledge of the amino acid sequences of ADPGK and GPD2, and the nucleotide sequences of the genes encoding these proteins (GPD2, nucleotide sequence: NCBI NM_001083112.2; amino acid sequence: UniProtKB canonical sequence P43304-1; ADPGK, nucleotide sequence: NCBI NM_031284.4 (496 aa isoform)+NM_031284.2 (497 aa isoform); amino acid sequence: UniProtKB canonical sequence Q9BRR6-2 (496 aa isoform)+Q9BRR6-1 (497 aa isoform).
In a further preferred embodiment of the present invention, the compound useful for reducing or inhibiting the expression of the gene encoding ADPGK or GPD2 is an antisense oligonucleotide or siRNA specific for said gene.
The generation of suitable antisense oligonucleotides includes determination of a site or sites within the ADPGK or GPD2 encoding gene for the antisense interaction to occur such that the desired effect, e.g., inhibition of the expression of the protein, will result. A preferred intragenic site is (a) the region encompassing the translation initiation or termination codon of the open reading frame (ORF) of the gene or (b) a region of the mRNA which is a “loop” or “bulge”, i.e., not part of a secondary structure. If one or more target sites have been identified, oligonucleotides are chosen which are sufficiently complementary to the target, i.e., hybridize sufficiently well and with sufficient specificity, to give the desired effect. In the context of this invention, “hybridization” means hydrogen bonding, which may be Watson-Crick, Hoogsteen or reversed Hoogsteen hydrogen bonding, between complementary nucleoside or nucleotide bases. “Complementary” as used herein, refers to the capacity for precise pairing between two nucleotides. For example, if a nucleotide at a certain position of an oligonucleotide is capable of hydrogen bonding with a nucleotide at the same position of a DNA or RNA molecule, then the oligonucleotide and the DNA or RNA are considered to be complementary to each other at that position. The oligonucleotide and the DNA or RNA are complementary to each other when a sufficient number of corresponding positions in each molecule are occupied by nucleotides which can make hydrogen bonds with each other. Thus, “specifically hybridizable” and “complementary” are terms which are used to indicate a sufficient degree of complementarity or precise pairing such that stable and specific binding occurs between the oligonucleotide and the DNA or RNA target. It is understood in the art that the sequence of an antisense compound does not need to be 100% complementary to that of its target nucleic acid to be specifically hybridizable. An antisense compound is specifically hybridizable when binding of the compound to the target DNA or RNA molecule interferes with the normal function of the target DNA or RNA to cause a loss of utility, and there is a sufficient degree of complementarity to avoid non-specific binding of the antisense compound to non-target sequences under conditions in which specific binding is desired, i.e., in the case of therapeutic treatment.
The skilled person can generate antisense compounds and siRNAs according to the present invention on the basis of the known DNA sequences for ADPGK and GPD2, respectively.
“Oligonucleotide” refers to an oligomer or polymer of ribonucleic acid (RNA) or deoxyribonucleic acid (DNA) or mimetics thereof. This term includes oligonucleotides composed of naturally-occurring nucleobases, sugars and covalent internucleoside (backbone) linkages as well as oligonucleotides having non-naturally-occurring portions which function similarly. Such modified or substituted oligonucleotides are often preferred over native forms because of desirable properties such as, for example, enhanced cellular uptake, enhanced affinity for nucleic acid target and increased stability in the presence of nucleases. While antisense oligonucleotides are a preferred form of the antisense compound, the present invention comprehends other oligomeric antisense compounds, including but not limited to oligonucleotide mimetics such as are described below. The antisense compounds in accordance with this invention comprise from about 8 to about 50 nucleobases (i.e. from about 8 to about 50 linked nucleosides). Particularly preferred antisense compounds are antisense oligonucleotides, even more preferably those comprising from about 15 to about 25 nucleobases. Antisense compounds include ribozymes, external guide sequences (EGS), oligonucleotides (oligozymes), and other short catalytic RNAs or catalytic oligonucleotides which hybridize to the target nucleic acid and inhibit its expression.
Alternatively, the compound of the invention is a vector allowing to transcribe an antisense oligonucleotide of the invention, e.g., in a mammalian host. Preferably, such a vector is a vector useful for gene therapy. Preferred vectors useful for gene therapy are viral vectors, e.g. adenovirus, herpes virus, vaccinia, or, more preferably, an RNA virus such as a retrovirus. Even more preferably, the retroviral vector is a derivative of a murine or avian retrovirus. Examples of such retroviral vectors which can be used in the present invention are: Moloney murine leukemia virus (MoMuLV), Harvey murine sarcoma virus (HaMuSV), murine mammary tumor virus (MuMTV) and Rous sarcoma virus (RSV). Most preferably, a non-human primate retroviral vector is employed, such as the gibbon ape leukemia virus (GaLV), providing a broader host range compared to murine vectors. Since recombinant retroviruses are defective, assistance is required in order to produce infectious particles. Such assistance can be provided, e.g., by using helper cell lines that contain plasmids encoding all of the structural genes of the retrovirus under the control of regulatory sequences within the LTR. Suitable helper cell lines are well known to those skilled in the art. Said vectors can additionally contain a gene encoding a selectable marker so that the transduced cells can be identified. Moreover, the retroviral vectors can be modified in such a way that they become target specific. This can be achieved, e.g., by inserting a polynucleotide encoding a sugar, a glycolipid, or a protein, preferably an antibody. Those skilled in the art know additional methods for generating target specific vectors. Further suitable vectors and methods for in vitro- or in vivo-gene therapy are described in the literature and are known to the persons skilled in the art; see, e.g., WO 94/29469 or WO 97/00957.
In order to achieve expression only in the target organ the DNA sequences for transcription of the antisense oligonucleotides can be linked to a tissue specific promoter and used for gene therapy. Such promoters are well known to those skilled in the art.
Within an oligonucleotide structure, the phosphate groups are commonly referred to as forming the internucleoside backbone of the oligonucleotide. The normal linkage or backbone of RNA and DNA is a 3′ to 5′ phosphodiester linkage. Specific examples of preferred antisense compounds useful in the present invention include oligonucleotides containing modified backbones or non-natural internucleoside linkages. Oligonucleotides having modified backbones include those that retain a phosphorus atom in the backbone and those that do not have a phosphorus atom in the backbone. Modified oligonucleotide backbones which can result in increased stability are known to the person skilled in the art, preferably such modification is a phosphorothioate linkage.
A preferred oligonucleotide mimetic is an oligonucleotide mimetic that has been shown to have excellent hybridization properties, and is referred to as a peptide nucleic acid (PNA). In PNA compounds, the sugar-backbone of an oligonucleotide is replaced with an amide containing backbone, in particular an aminoethylglycine backbone. The nucleobases are retained and are bound directly or indirectly to aza nitrogen atoms of the amide portion of the backbone.
Modified oligonucleotides may also contain one or more substituted or modified sugar moieties. Preferred oligonucleotides comprise one of the following at the 2′ position: OH; F; 0-, S-, or N-alkyl; 0-, S-, or N-alkenyl; 0-, S- or N-alkynyl; or 0-alkyl-O-alkyl, wherein the alkyl, alkenyl and alkynyl may be substituted or unsubstituted C1 to C10 alkyl or C2 to C10 alkenyl and alkynyl. A particularly preferred modified sugar moiety is a 2′-O-methoxyethyl sugar moiety.
Oligonucleotides of the invention may also include nucleobase modifications or substitutions. Modified nucleobases include other synthetic and natural nucleobases such as 5-methylcytosine (5-me-C), 5-hydroxymethyl cytosine, xanthine, hypoxanthine, 2-aminoadenine, 6-methyl and other alkyl derivatives of adenine and guanine, 2-propyl and other alkyl derivatives of adenine and guanine, 2-thiouracil, 2-thiothymine and 2-thiocytosine etc., with 5-methylcytosine substitutions being preferred since these modifications have been shown to increase nucleic acid duplex stability.
Another modification of the oligonucleotides of the invention involves chemically linking to the oligonucleotide one or more moieties or conjugates which enhance the activity, cellular distribution or cellular uptake of the oligonucleotide. Such moieties include lipid moieties such as a cholesterol moiety, cholic acid, a thioether, a thiocholesterol, an aliphatic chain, e.g., dodecandiol or undecyl residues, a phospholipid, a polyamine or a polyethylene glycol chain, or adamantane acetic acid, a palmityl moiety, or an octadecylamine or hexylamino-carbonyl-oxycholesterol moiety.
The present invention also includes antisense compounds which are chimeric compounds. “Chimeric” antisense compounds or “chimeras,” in the context of this invention, are antisense compounds, particularly oligonucleotides, which contain two or more chemically distinct regions, each made up of at least one monomer unit, i.e., a nucleotide in the case of an oligonucleotide compound. These oligonucleotides typically contain at least one region wherein the oligonucleotide is modified so as to confer upon the oligonucleotide increased resistance to nuclease degradation, increased cellular uptake, and/or increased binding affinity for the target nucleic acid. An additional region of the oligonucleotide may serve as a substrate for enzymes capable of cleaving RNA:DNA or RNA:RNA hybrids. By way of example, RNase H is a cellular endonuclease which cleaves the RNA strand of an RNA:DNA duplex. Activation of RNase H, therefore, results in cleavage of the RNA target, thereby greatly enhancing the efficiency of oligonucleotide inhibition of gene expression. Consequently, comparable results can often be obtained with shorter oligonucleotides when chimeric oligonucleotides are used, compared to phosphorothioate deoxyoligonucleotides hybridizing to the same target region. Chimeric antisense compounds of the invention may be formed as composite structures of two or more oligonucleotides, modified oligonucleotides, oligonucleosides and/or oligonucleotide mimetics as described above. Such compounds have also been referred to in the art as hybrids or gapmers.
In a further preferred embodiment, the compound of the present invention is used for the treatment of (i) a neoplasm or (b) an autoimmune disease, or Graft-versus-Host Disease (GvHD).
“Neoplasm” is an abnormal mass of tissue as a result of neoplasia. “Neoplasia” is the abnormal proliferation of cells. The growth of the cells exceeds and is uncoordinated with respect to the normal tissues around it. The growth persists in the same excessive manner, even after cessation of the stimuli. It usually causes a lump or tumor. Neoplasms may be benign, pre-malignant (carcinoma-in-situ) or malignant (cancer). The neoplasms to be treated according to the present invention comprise those which (over)express ADPGK and/or GPD2. Thus, the determination of ADPGK and/or GPD2 in a neoplasm is an indication to start with a ADPGK and/or GPD2 inhibiting therapy. A neoplasm to be treated is particularly B cell chronic lymphocytic leukemia or any neoplasm characterized in that T cell activation shows a beneficial effect, i.e., tumors of the immune system and tumors characterized by constitutive activation of NF-kappaB and/or increased ROS levels. Examples of such tumors are Multiple Myeloma (MM), Diffuse large B cell Lymphoma, Acute Myelogenous leukemia (AML), Chronic myelogenous leukemia (CML), Adult T cell lymphoma (ATL), childhood/T cell acute lymphoblastic leukemia (ALL/T-ALL), Hodgin Lymphoma (HL), Non-Hodgin Lymphoma, Malt lymphoma, Cutaneous T-cell lymphoma (CTCL), e.g., Sézary Syndrom (SS) and Hepatocellular Carcinoma (HCC).
Preferred autoimmune diseases that can be treated with a compound of the present invention are, e.g., rheumatism, Lupus erythematodes, Psoriasis, atopic dermatitis, multiple sclerosis, or diabetes.
Further examples of compounds capable of reducing or inhibiting the biological activity of ADPGK or GPD2 are (neutralizing) antibodies directed against these proteins or fragments thereof having substantially the same binding specificity or pseudo-substrates. The term “antibody”, preferably, relates to antibodies which consist essentially of pooled monoclonal antibodies with different epitopic specificities, as well as distinct monoclonal antibody preparations. Monoclonal antibodies are made from an antigen containing, e.g., a fragment of ADPGK or GPD2 by methods well known to those skilled in the art (see, e.g., Köhler et al., Nature 256 (1975), 495). As used herein, the term “antibody” (Ab) or “monoclonal antibody” (Mab) is meant to include intact molecules as well as antibody fragments (such as, for example, Fab and F(ab′)2 fragments) which are capable of specifically binding to protein. Fab and F(ab′)2 fragments lack the Fc fragment of intact antibody, clear more rapidly from the circulation, and may have less non-specific tissue binding than an intact antibody. (Wahl et al., J. Nucl. Med. 24: 316-325 (1983)). Thus, these fragments are preferred, as well as the products of a FAB or other immunoglobulin expression library. Moreover, antibodies useful for the purposes of the present invention include chimerical, single chain, and humanized antibodies.
Alternatively, preferred compounds for the purposes of the invention are inactive versions of ADPGK and GPD2, respectively, or nucleic acid sequences encoding inactive versions of these proteins that can be introduced according to the approaches/vectors described above. Such inactive versions can be generated according to well known methods of mutagenesis. Such compounds can have a therapeutic effect in the human body by displacing their functionally active counterpart, in particular when applied in excess. Analyses of potentially inactive versions of ADPGK/GPD2 can be carried out by assaying the (reversible) transamination of branched-chain L-amino acids to branched-chain alpha-keto acids, e.g., by determining the production of glutamate. Suitable assays are described in the literature.
In a further preferred embodiment, the compound of the present invention is a compound that increases the activity of ADPGK and/or GDP2, preferably by increasing the level of these proteins. This can be achieved, e.g., by increasing gene expression using methods/vectors known by the person skilled in the art. Such compounds are useful for the treatment of diseases that are characterized by a low level of ADPGK and/or GPD2 or diseases wherein the increase of the activity/level of ADPGK and/or GPD2 might have a beneficial effect, e.g., a disease of the immune system which is low immunity or acquired immune deficiency syndrome, e.g., caused by HIV.
The present invention also relates to a method for identifying a compound capable of modulating the biological activity of ADPGK or GPD2 and/or the expression of ADPGK or GPD2, comprising the steps of:
The increase or reduction of the biological activity of ADPGK and/or GPD2 can be assayed by determining the concentration of the protein, e.g., by use of a specific antibody or by directly determining the enzymatic activity of the protein, e.g., by determining the change of the concentration of a specific substrate or end product as described, e.g., in Example 1.
Examples of such candidate molecules include antibodies, oligonucleotides, proteins, or small molecules. Such molecules can be rationally designed using known techniques.
Preferably, said test system used for screening comprises substances of similar chemical and/or physical properties, most preferably said substances are almost identical. The compounds which can be prepared and identified according to a use of the present invention may be expression libraries, e.g., cDNA expression libraries, peptides, proteins, nucleic acids, antibodies, small organic compounds, ligands, hormones, peptidomimetics, PNAs or the like.
WO 98/25146 describes further methods for screening libraries of complexes for compounds having a desired property, especially, the capacity to agonize, bind to, or antagonize a polypeptide or its cellular receptor. The complexes in such libraries comprise a compound under test, a tag recording at least one step in synthesis of the compound, and a tether susceptible to modification by a reporter molecule. Modification of the tether is used to signify that a complex contains a compound having a desired property. The tag can be decoded to reveal at least one step in the synthesis of such a compound. Other methods for identifying compounds which interact with ADPGK and GPD2, respectively, or nucleic acid molecules encoding such molecules are, for example, the in vitro screening with the phage display system as well as filter binding assays or “real time” measuring of interaction.
It is also well known to the person skilled in the art, that it is possible to design, synthesize and evaluate mimetics of small organic compounds that, for example, can act as a substrate or ligand to ADPGK or GPD2.
All these methods can be used in accordance with the present invention to identify a compound modulating, e.g., reducing or inhibiting the biological activity of ADPGK or GPD2 or their expression.
The gene encoding ADPGK or GPD2 can also serve as a target for the screening of activators or inhibitors, e.g., immune suppressive modulators. Inhibitors may comprise, for example, proteins that bind to the mRNA of the genes encoding ADPGK or GPD2, thereby destabilizing the native conformation of the mRNA and hampering transcription and/or translation. Furthermore, methods are described in the literature for identifying nucleic acid molecules such as a RNA fragment that mimics the structure of a defined or undefined target RNA molecule to which a compound binds inside of a cell resulting in the retardation of the cell growth or cell death; see, e.g., WO 98/18947 and references cited therein. These nucleic acid molecules can be used for identifying unknown compounds of pharmaceutical interest, and for identifying unknown RNA targets for use in treating a disease. These methods and compositions can be used for identifying compounds useful to reduce expression levels of ADPGK or GPD2.
The compounds which can be tested and identified according to the method of the invention may be expression libraries, e.g., cDNA expression libraries, peptides, proteins, nucleic acids, antibodies, small organic compounds, hormones, peptidomimetics, PNAs or the like. Furthermore, genes encoding a putative regulator of ADPGK or GPD2 and/or which exert their effects up- or downstream of ADPGK or GPD2 may be identified using insertion mutagenesis using, for example, gene targeting vectors known in the art. Said compounds can also be functional derivatives or analogues of known inhibitors, substrates or modulators. Such useful compounds can be for example transacting factors which bind to ADPGK or GPD2 or regulatory sequences of the gene encoding it. Identification of transacting factors can be carried out using standard methods in the art. To determine whether a protein binds to the protein itself or regulatory sequences, standard native gel-shift analyses can be carried out. In order to identify a transacting factor which binds to the protein or regulatory sequence, the protein or regulatory sequence can be used as an affinity reagent in standard protein purification methods, or as a probe for screening an expression library. The identification of nucleic acid molecules which encode polypeptides which interact with ADPGK or GPD2 can also be achieved, for example, by use of the so-called yeast “two-hybrid system”. In this system ADPGK or GPD2 is linked to the DNA-binding domain of the GAL4 transcription factor. A yeast strain expressing this fusion polypeptide and comprising a lacZ reporter gene driven by an appropriate promoter, which is recognized by the GAL4 transcription factor, is transformed with a library of cDNAs which will express plant proteins or peptides thereof fused to an activation domain. Thus, if a peptide encoded by one of the cDNAs is able to interact with the fusion peptide comprising a peptide of ADPGK or GPD2, the complex is able to direct expression of the reporter gene. In this way, ADPGK or GPD2 and the gene encoding ADPGK or GPD2 can be used to identify peptides and proteins interacting with ADPGK or GPD2. It is apparent to the person skilled in the art that this and similar systems may then further be exploited for the identification of inhibitors.
Finally, the present invention relates to a method of selecting a therapy modality for a patient afflicted with a disease as characterized above, comprising
Preferably, the level of ADPGK or GPD2 is determined on the protein level using an antibody that specifically binds to ADPGK or GPD2 or by determining a biological activity of the protein.
In the method of the present invention which relates to the selection of a therapy modality for a patient, the terms “therapy modality” or “mode of treatment” refer to a timely sequential or simultaneous administration of compounds having an effect on the level/activity of ADPGK and GPD2, respectively, provided that the results of the method of the invention indicate that the disease is associated with an aberrant level/activity of ADPGK and/or GPD2.
The below examples explain the invention in more detail.
(A) Chemicals
If not stated differently all reagents and enzymes used were supplied by Sigma-Aldrich (Munich, Germany). Dichlorodihydrofluorescein diacetate (H2DCF-DA) was obtained from Invitrogen (Carlsbad, Calif., USA). Iono was purchased from Merck (Darmstadt, Germany). Primary antibodies for Western blot (WB) were: from Sigma-Aldrich (Munich, Germany)—mouse monoclonal anti-FLAG (M2), rabbit polyclonal anti-FLAG, mouse monoclonal anti-γ-tubulin, rabbit polyclonal anti-GPD2 (Human Protein Atlas Antibodies); from Cell Signaling (Denvers, Mass., USA)—rabbit polyclonal anti-HK1 and rabbit polyclonal anti-HK2; from Abcam (Cambridge, UK)—mouse monoclonal anti-human ADPGK (1E4); from Santa Cruz Biotechnology (Santa Cruz, Calif., USA)—goat polyclonal anti-SOD1; from Milipore (Darmstadt, Germany)—rabbit polyclonal anti-SOD2, from ABR (Golden, Colo., USA)—rabbit polyclonal anti-calreticulin; from GeneTex (Irvine, Calif., USA)—rabbit polyclonal anti-β-actin and from Thermo Scientific (Bonn, Germany)—mouse monoclonal anti-PHB1 antibody (II-14-10). Content of mitochondrial respiratory complexes was analyzed using Total OXPHOS WB Antibody Cocktail from Mito Sciences (Eugene, Oreg., USA). FITC-conjugated anti-CD3 and anti-CD20 antibodies were from Becton Dickinson (Heidelberg, Germany). Cross-linking polyclonal goat anti-mouse antibody (GAM) was obtained from Southern Biotech (Birmingham, Ala., USA). Monoclonal mouse antibody (OKT3) against human CD3 was prepared as described (1).
(B) Isolation of Human Peripheral T Cells and B Cells
Generally, human peripheral blood T lymphocytes were purified as described previously (1). Human peripheral blood B lymphocytes were prepared from the Ficoll gradient inter-phase ring by negative MACS sorting (“B Cell Isolation Kit II”, Miltenyi, Bergisch Gladbach, Germany). Homogeneity of the prepared T and B cells was verified by staining with FITC-conjugated anti-CD3 or anti-CD20 antibodies followed by FACS analysis and was estimated to be >93% (B cells) and >90% (T cells).
(C) Patients
Informed consent was obtained from all subjects before inclusion. 9 out of 10 patients did not receive treatment prior to the therapy. Patient data (age, gender and genetic analysis of CLL samples) can be found in Table 1. B cells from CLL patients were isolated by Ficoll-Paque centrifugation (GE Healthcare; Chalfont St. Giles, UK). Purity was estimated to be >90%. The study was conducted according to the ethical guidelines of the German Cancer Research Center (DKFZ, Heidelberg) and the Helsinki Declaration, and approved by the ethics committee II of the Ruprecht-Karls-University of Heidelberg, Germany.
(D) Cell Culture
T cell line Jurkat J16-145 cells, J16 sub-clone (2), were cultured in RPMI 1640 (+L-glutamine), 10% foetal calf serum (FCS). Gaussia luciferase NF-κB reporter J16-145 cells were cultured in IMDM, 10% FCS. Freshly isolated (“resting”) or phytohemagglutinin (PHA)-activated and 6-8 days in vitro expanded (“pre-activated”) peripheral human T cells were cultured at initial concentration of 2×106 cells/ml in RPMI 1640 (+L-glutamine), 10% FCS. For pre-activation-induced expansion, “resting” T cells were treated with 1 μg/ml PHA for 16 h, washed and subsequently cultured in the presence of 25 U/ml IL-2 for 6-8 days. These cells are referred to as “T cells” in the text, if not stated differently.
(E) Determination of ROS Generation
Cells were stained with H2DCF-DA (5 μM) for 30 min. Next, cells were divided and 1 h stimulated with either plate-bound anti-CD3 antibody (30 μg/ml) or PMA (10 ng/ml). Treatment was terminated by ice-cold PBS and ROS generation was determined by FACS analysis (Canto II, Becton Dickinson). ROS generation was quantified as the increase in mean fluorescence intensity (MFI), calculated according to the following formula: increase in MFI (%)=[(MFIstimulated−MFIunstimulated)/MFIunstimulated]×100 (3).
(F) Digitonin-Permeabilized Cells
In vitro expanded T cells (at least 0.5×108) were snap-frozen in liquid nitrogen and subsequently incubated on ice in ETC buffer (20 mM Tris-HCl pH 7.4, 250 mM sucrose, 50 mM KCl, 5 mM MgCl2) with 0.015% digitonin for 30 min according to Chretien et al. (4) with minor modifications. Afterwards, cells were washed twice with ice-cold ETC buffer and subjected to assays.
(G) Preparation of Sub-Cellular Fractions
Cells were disrupted using a 27×½″ needle in ice-cold ETC buffer and the homogenates were centrifuged at 600×g, 4° C. for 10 min. For preparation of the “high g” mitochondrial (pellet) as well cytosolic (supernatant) fraction the 600×g supernatant was centrifuged at 11.000×g, 4° C. for 20 min. For preparation of the “mitochondria-enriched” fractions, the 600×g supernatant was centrifuged 10 min, 4° C. at 3,500×g (pellet). Subsequently, for preparation of the “ER-enriched fraction” the 3,500×g supernatant was centrifuged at 11.000×g, 4° C. for 20 min. The mouse heart muscle mitochondria were prepared according to the procedure for “mitochondria-enriched” fraction as described (5).
(H) Electron Transport Chain (ETC) and Electron Flux
Steady-state activity of ETC enzymatic complexes was determined as described (5, 6) using a computer-tunable spectrophotometer (Spectramax Plus Microplate Reader, Molecular Devices; Sunny Vale, Calif., USA) operating in the dual wavelength mode; samples were analyzed in temperature-controlled 96-well plates in a final volume of 300 μL. The addition of standard respiratory chain inhibitors was used to ascertain the specificity of the enzymatic assays. All enzymatic activities were normalized to protein concentration. For stimulated T cells ETC enzyme activities were measured after snap-freezing and digitonin-permeabilization (as described previously). To study electron flow from complex I or complex II to complex III digitonin-permeabilized cells or mitochondrial fractions were incubated with NADH or succinate and the reduction of cytochrome c in the presence of NaCN was measured.
(I) Activity Measurement of Glycolytic Enzymes
All enzymes applied were purchased from Sigma-Aldrich and prepared from rabbit muscle.
Hexokinase (HK) activity was assayed as NADP reduction in ETC buffer containing 1 mM ATP, 1 mM glucose, 0.5 mM NADP, 0.05 U/ml glucose 6-phosphate dehydrogenase.
Glyceraldehyde-phosphate dehydrogenase (GAPDH) activity was detected as NAD reduction in a buffer containing 10 mM KPi, 1 mM NAD, 3.3 mM cysteine 0.2 mM EDTA, 0.2 mM MgCl2, 1 mM ADP.
Glycerol-3-phosphate-dehydrogenase (GPD2) activity was measured as cytochrome c reduction in ETC buffer containing 5 mM glycerol 3-phosphate, 2 mM NaCN, and 60 μM cytochrome c.
Trioso-phosphate isomerase (TPI) activity was assayed as NADH oxidation in ETC buffer containing 0.2 mM NADH, 4.9 mM DL-glyceraldehyde 3-phosphate, 0.4 U/ml α-glycerophosphate dehydrogenase (GPD1).
Phosphofructokinase (PFK) activity was detected as NADH oxidation in ETC buffer containing 4 mM fructose 6-phosphate, 2 mM ATP, 0.5 mM NADH, 0.2 U/ml aldolase, 0.8 U/ml TPI, 0.1 U/ml GPD1.
Pyruvate kinase (PK) activity was detected as NADH oxidation in ETC buffer containing 1 mM phosphoenolpyruvate, 1 mM ADP, 0.5 mM NADH, 2 U/ml LDH.
Lactate dehydrogenase (LDH) activity was recorded as NADH oxidation in ETC buffer containing 1 mM pyruvate, 0.5 mM NADH.
Enolase (ENO) forward reaction was measured as NADH oxidation in ETC buffer containing 1 mM 2-phosphoglycerate, 1 mM ADP, 0.5 mM NADH, 2 U/ml LDH, 2 U/ml PK. The reverse reaction was assayed in ETC buffer containing 1 mM phosphoenolpyruvate, 1 mM ATP, 0.5 mM NADH, 2 U/ml LDH, 2 U/ml PK.
Phosphoglycerate mutase (PGM) activity was recorded as NADH oxidation in ETC buffer containing 1 mM 2-phosphoglycerate, 1 mM ATP, 1 mM phosphoenolpyruvate, 0.5 mM NADH, 2 U/ml LDH, 2 U/ml PK. The reverse reaction was assayed in ETC buffer containing 1 mM 3-phosphoglycerate, 1 mM ADP, 0.5 mM NADH, 2 U/ml LDH, 2 U/ml PK.
Phosphoglycerate kinase (PGK) reverse reaction was assayed in ETC buffer containing 1 mM 3-phosphoglycerate, 1 mM ATP, 0.5 mM NADH, 2 U/ml LDH, 2 U/ml PK.
(J) Fructose-6-Phosphate Flux
Fructose-6-phosphate flux via GPD pathway was measured as NADH oxidation in ETC buffer containing 1 mM fructose 6-phosphate, 1 mM ATP, 0.5 mM NADH, 0.1 U/ml GPD1. The flux through the GAPDH branch was recorded in ETC buffer containing 1 mM KPi, 1 mM fructose 6-phosphate, 1 mM ATP, 0.5 mM NAD, 0.1 U/ml GAPDH.
(K) Glucose Uptake
Upon treatment, cells (1-2×107 cells) were washed and suspended in Krebs-Ringer buffer. Subsequently, cells were incubated with 1 μCi/ml D-[3-3H] glucose for 10 min at 37° C. Afterwards, cells were washed twice with ice-cold Krebs-Ringer buffer and intracellular D-[3-3H] glucose was detected using a scintillation counter (LS 6500 Liquid Scintillation Counter Beckman Coulter; Brea, Calif., USA).
(L) Oxygen Electrode
Mitochondrial respiratory rate was measured according to a previously described protocol (7) using computer-supported high-resolution Oroboros 1 oxygraph system (Paar, Graz, Austria). In vitro expanded T cells (5-10×107 cells) were placed in each electrode chamber and activated with soluble anti-CD3 antibody (10 μg/m, cross-linked with GAM, 2 μg/ml) or PMA (10 ng/ml). The experimental set-up was as previously described (8). “Mitochondrial respiratory rate” was calculated by subtracting “Background oxygen consumption rate” (recorded with a reference electrode in a presence of 5 μM oligomycin) from “Total oxygen consumption rate” (as described in (8)).
(M) Lactate Quantitation
At least 2×107 expanded T cells were suspended in fresh RPMI 1640 medium (+supplements and IL-2), then activated with soluble anti-CD3 antibody (10 μg/ml) cross-linked with GAM (2 μg/ml) for 1 h. Lactate concentrations in media were detected using an Olympus AU400 system (Olympus, Tokyo, Japan) and normalized to protein concentration of respective cellular lysates.
(N) ADP-Dependent Glucokinase (ADPGK) Activity Assay
ADPGK activity was assayed as NADP reduction in ETC buffer containing 1 mM ADP, 1 mM glucose, 0.5 mM NADP, 5 μM diadenosine pentaphosphate, and 0.05 U/ml glucose 6-phosphate dehydrogenase at pH 6.0 and 37° C. or 42° C. Assay was essentially based on the one previously described for the recombinant mouse ADPGK protein (9).
(O) Adenylate Kinase (AK) Activity Assay
AK activity was assayed as NADP reduction in ETC buffer containing 1 mM ADP, 1 mM glucose, 0.5 mM NADP, 1 U/mL HK and 0.05 U/ml glucose 6-phosphate dehydrogenase at pH 7.5 and 37° C.
(P) ATP Content Determination
ATP concentration was determined using a “CELLTITER GLO” assay (Promega) according to the manufacturer's instructions and 96-well luminometer (Orion L, Berthold; Bad Wildbad, Germany). Results were normalized to the protein concentration.
(Q) Ubiquinol/Ubiquinone Content Determination
At least 5×107 in vitro expanded human T cells were treated with plate-bound anti-CD3 antibody (30 μg/ml) or PMA (10 ng/ml) for 1 h. Cells were washed, pelleted, snap-frozen in liquid nitrogen and placed on dry ice. Ubiquinol/-on extraction was performed by addition of ice-cold 200 μl hexan: isopropanol (2:1) and subsequent centrifugation (15.000 g) for 5 min at 0° C. Next, 150 μl of the supernatant was immediately injected and separated by RP-HPLC. HPLC separation and identification conditions were based on previously published methods (10, 11). Chromatographic system applied: LaChrom LC-7100 low pressure gradient pump with proportioning valves, L-7350 column thermostat with L-7350/L-7351 Peltier cooling module, L-7450A UV/VIS-DAD—diode-array detector (Merck-Hitachi; Darmstadt, Germany), pulsed amperometric detector (PAD) 817 Bioscan (Metrohm; Herisau, Switzerland), column LiChrospher RP18e 125×4 mm (Merck; Darmstadt, Germany), 4-channel degasser (Knauer; Berlin, Germany), isocratic elution with methanol:hexan:isopropanol:acetic acid (83:27.5:1.5:1.5 v/v+sodium acetate 4.2 g/1; pH=6), flow rate—1 ml/min, temp. 25° C. Identification was based on UV/VIS-DAD absorption spectra and facilitated by redox response detected with volt-amperometric detector. Quantitation was performed based on UV-VIS chromatograms at wavelengths: 275 nm (ubiquinone) and 289 nm (ubiquinol). Selected qualitative and quantitative results of UV-VIS/DAD analysis were confirmed by HPLC-MS/ESI (Agilent; Santa Clara, Calif., USA).
(R) Luciferase Reporter Assay for NF-KB Activation
J16-145 Jurkat T cells stably transfected with Gaussia luciferase-based NF-κB reporter were kindly provided by Dr. Marcus Brechman and Dr. Rüdiger Arnold. Briefly, after exchanging medium cells were induced with Iono (10 μM) and/or PMA (10 ng/ml) for 6 h in triplicates for each experimental condition. 20 μl of collected medium was applied to luminescence read-out using “Gaussia-Juice” (P.J.K.; Kleinblittersdorf, Germany) and 96-well plate luminometer (Orion L; Berthold, Bad Wildbad, Germany). Luminescence signal was normalized to the number of living cells assessed by Trypan-Blue exclusion method.
(S) Immunoprecipitation and WB
At least 8×107 F-ADPGK or EV Jurkat T cells were lysed in a buffer containing 150 mM NaCl, 5 mM EDTA, 10 mM Tris-HCl, 0.5% TRITON X-100 for 45 min at 4° C. Lysats were centrifuged at 11.000 g, 4° C. for 10 min. Supernatants were applied onto agarose beads covalently cross-linked with anti-FLAG M2 antibodies (ANTI-FLAG® M2 Affinity Gel, Sigma). Washing steps and elution with FLAG peptide were performed according to manufacturer's protocol. Eluats were directly subjected to ADPGK activity assay or frozen and analyzed by WB (3).
(T) ADPGK Over-Expression Experiments
For transient expression of WT-ADPGK cDNA sequence of human ADPGK transcript variant 1 (UniProtKB canonical sequence Q9BRR6-1) cloned into pCMV6-AC plasmid (provided by Origene; Rockville, Md., USA) or empty control pCMV6-AC vector (Origene) were used. J16-145 cells or J16-145 Gaussia luciferase reporter clone were transfected with 2 μg plasmid DNA/transfection using AMAXA nucleofection technology (“Cell Line Nucelofector® V kit”, Lonza; Cologne, Germany) according to the manufacturer's instructions. 24 h post-transfection cells were subjected to the experimental procedures. Pools of J16-145 cells stably expressing FLAG-ADPGK protein (F-ADPGK Jurkat cells) or empty-vector (control cells) were generated using retroviral expression vectors provided by Addgene (Cambridge, Mass., USA): pWZL-Neo-Myr-Flag-ADPGK (Addgene plasmid 20417, N-terminal FLAG-tag on a protein backbone, UniProtKB Q9BRR6-1) or pWZL-Neo-Myr-Flag-DEST (Addgene plasmid 15300), respectively (12). Retroviral vectors were transfected by calcium phosphate method into PHOENIX-AMPHO producing cells (Allele Biotechnology; San Diego, Calif., USA). Viral transduction was performed according to manufacturer's protocol using polybrene and spin-infection (2 h/2.000 g). Cells were cultured under a selection pressure in RPMI 1640 (+L-glutamine), 10% FCS supplemented with 1 mg/ml G418 sulphate (Roth; Karlsruhe, Germany).
(U) Real Time Quantitative Reverse Transcription Time PCR (Real Time qRT-PCR)
RNA was isolated with TRIZOL reagent (Invitrogen) (CLL cells and control B cells) or “RNEASY Mini” kit (QIAGEN; Hilden, Germany) (all other samples) according to the manufacturer's instructions. Total RNA (1 μg) was reverse-transcribed with a “Reverse Transcription (RT)-PCR kit” (Applied Biosystems; Carlsbad, Calif., USA). Quantitative real-time-PCR was performed using the “Power SYBR Green PCR Master Mix” (Applied Biosystems). Gene expression was analyzed using the 7500 Real-Time PCR Systems and Sequence Detection Software, Applied Biosystems, v. 2.0.2. Gene expression levels were normalized using β-actin expression as an endogenous reference. Induction ratios (X) were calculated using the formula X=2−ΔΔCt where Ct stands for cycle threshold and ΔCt=Ctgene of interest−Ctreference gene. ΔΔCt is the difference between the ΔCt values of the “induced” samples and the ΔCt of the corresponding “non-induced” sample. The mean induction ratios were calculated. The relative ADPGK basal expression levels in B cell samples from CLL patients and healthy donors were compared using factor Y=2(Ct gene of interest-Ct GAPDH)×1000 (1). To correct for inter-experimental variation the values obtained from two separate experiments (two separate 96-well plates with triplicated 5 CLL samples and 4 or 5 healthy donor samples each) were subjected to z-transformation. The following primers were used for gene expression analysis: β actin, sense 5′-ACCGTGAGAAGATGACCCAGA-3′ (SEQ ID NO: 1), anti-sense 5′ TCACCGGAGTCCATCACGAT-3′ (SEQ ID NO: 2); IL-2, sense 5′-CAACTGGAGCATTTACTGCTG-3′ (SEQ ID NO: 3), anti-sense 5′-TCAGTTCTGTGGCCTTCTTGG-3′ (SEQ ID NO: 4); IL-8, sense 5′ GAATGGGTTTGCTAGAATGTGATA-3′ (SEQ ID NO: 5), anti-sense 5′ CAGACTAGGGTTGCCAGATTTAAC-3′ (SEQ ID NO: 6), ADPGK, sense 5′-TCATTGCAGGAAGTGGATGA-3′ (SEQ ID NO: 7), anti-sense 5′-GCATGGGGAGCTTTTAACTG-3′ (SEQ ID NO: 8), IκBα, sense 5′-GTCAAGGAGCTGCAGGAGAT-3′ (SEQ ID NO: 9), anti-sense 5′-GATGGCCAAGTGCAGGAA-3′ (SEQ ID NO: 10), GPD2, sense 5′-ACCCTGGCTGGAGGAACT3′ (SEQ ID NO: 11), anti-sense, 5′-CCCTTTCACTGCCTTTTGAA3′ (SEQ ID NO: 12) and IL-4 primers as published elsewhere (1).
(V) siRNA Transfection and Knock-Down
siRNA oligonucleotides used for transfection were as follows: non-silencing control (unlabeled “AllStars” non-silencing, validated siRNA, QIAGEN), specific for human ADPGK (Hs_ADPGK_5-8 FLEXITUBE siRNA, QIAGEN) or human GPD2 (Hs_GPD2_1, 4-6 FLEXITUBE siRNA, QIAGEN). Jurkat T cells or peripheral “resting” human T cells were transfected by nucleofection (“Cell Line Nucelofector® V kit” or “T Cell Nulcleofector® kit”, Lonza) performed with 800 nM of siRNA oligonucleotides according to the manufacturer's instructions.
(W) Blue-Native Polyacrylamide Gel Electrophoresis (BN-PAGE) and WB
BN-PAGE analysis of mitochondria-enriched fractions was performed according to Haeger et al. (13) with modifications. Protein complexes of the mitochondrial membrane were solubilized in the presence of 1.5 M 6-aminocaproic acid, 50 mM Bis-Tris and digitonin (6 g/g protein) at 4° C. for 30 min. Subsequently, samples were centrifuged at 11.000×g and 4° C. for 30 min. The supernatant was supplemented with sample buffer (1.5 M 6-aminocaproic acid, 50% glycerol, 1% (w/v) Coomassie blue G250) and immediately applied on a BN-Gel (3-13%). The gel was run for 16 h at a constant current of 35 V. Proteins were blotted for 2 h with a current limited to 0.8 mA/cm2 membrane. Bovine heart-purified complex III (BC1 complex) was a kind gift from Prof. Ulrich Brand.
A reduction of mitochondrial respiration and an increase in glycolysis are central to the Warburg effect (11-14). An oxygen electrode was applied to measure activation-induced changes in mitochondrial respiration of intact human T cells. In line with the Warburg phenotype, treatment with agonistic anti-CD3 antibody or PMA resulted in a significant inhibition of mitochondrial oxygen consumption (
To verify a causative link between observed metabolic changes and enhanced mitochondrial ROS production, the influence of 2-deoxy-glucose (DOG) and 3-bromopyruvate (BrPyr), blockers of glucose metabolism, on the generation of activation-induced ROS was tested. After brief pre-incubation (30 min) with DOG/pyruvate expanded human T cells and Jurkat T cells generated lower amounts of activation-induced ROS as compared to cells pre-incubated with equimolar concentrations of glucose (Glc)/pyruvate (
TCR-triggered PKCθ induces oxidative signal generation by mitochondrial respiratory complex I (3). To gain more insight into the relationship between the activation-induced Warburg metabolic shift and the mechanism of mitochondrial ROS release the bioenergetic status of respiratory chain complexes was investigated. To this end, snap-frozen and digitonin-permeabilized in vitro expanded human T cells were applied. As shown in
Furthermore, the observed differential pattern of enzymatic activities did not correspond with changes in the protein content of the respective complexes (
To better understand these phenomena, electron flow rates from complex I/II to complex III using either permeabilized cells or isolated mitochondria (
The observed bioenergetic changes could be attributed to the hyper-reduced state of ubiquinone, the electron carrier between complexes I/II and complex III (26,27). Accumulation of reduced ubiquinone (ubiquinol) is likely to decrease the activities of complex I and II in intact cells by blocking the electron flow. This effect would be lost after isolation of mitochondria due to the oxidation of ubiquinol (
To gain a better insight into the ubiquinone redox status upon T cell activation, the influence of a panel of respiratory chain inhibitors on oxidative signal generation was tested. According to the literature, the observed inhibition by complex I blockers, rotenone and metformin (1, 3), as well as moderate inhibition by the complex II blocker, TTFA, suggest a RET-based mechanism of activation-induced mitochondrial ROS release (
Mitochondrial ROS production induced by hyper-reduced ubiquinone is known to be associated with an increased glucose metabolism in hyperglycemic or hypoxic cells (18-21). To assay the glycolytic metabolic flow immediately after TCR triggering activities of all major glycolytic enzymes were measured (
It was suggested that PGM histidine phosphorylation reverses the flux through the lower glycolytic pathway initiated by GAPDH (29), and thus, could redirect it to the alternative flux through the cytosolic glycerol-3-phosphate dehydrogenase (GPD1/2) pathway. Indeed, TCR triggering clearly enhanced fructose-6-phosphate metabolism in the direction of GPD1, while GAPDH-mediated fructose-6-phosphate turn-over was slightly decreased (
GPD2 transfers electrons to the respiratory chain via reduction of ubiquinone. Therefore, up-regulation of its enzymatic activity could result in a RET-mediated ROS release due to hyper-reduced ubiquinone (26,27, 34-36). To investigate this possibility, the effects of down-regulation of GPD2 expression on activation-dependent oxidative signal generation, NF-κB triggering and gene expression were analyzed. siRNA-mediated knock-down of GPD2 expression resulted in a decreased generation of the oxidative signal (
Furthermore, BN-PAGE-based WB strongly suggested an association of GPD2 with respiratory complex III (
Glucose-induced hyper-reduction of ubiquinone and mitochondrial ROS release are thought to depend on up-regulated glycolytic flux (18,19). Glycolysis is a highly regulated sequence of reactions with major regulatory points at HK, PFK, GAPDH, and PK (
Indeed, enhanced ADPGK activity occurred in mitochondria-enriched membrane fractions (“high g” fractions) isolated from anti-CD3-treated human T cells (
ADPGK activity in “ER-enriched” fractions was characterized with respect to its kinetic parameters. The enzyme revealed a striking pH optimum of 6.0 and a Km for glucose of 0.086 mM (pH 6.0, 37° C.). Obtained values resemble the ones reported for mouse recombinant ADPGK (38), and are in a range similar to so-called low-Km HKs 1-3. Furthermore, ADPGK was substrate-inhibited at glucose concentrations higher than 5 mM.
Next, Jurkat T cells stably expressing ADPGK protein with an N-terminal FLAG tag were generated (F-ADPGK Jurkat cells,
Next, the influence of lowering ADPGK expression on activation-induced ROS generation was assayed. Decreased expression of ADPGK (
Furthermore, enhanced PMA-induced ADPGK activity in F-ADPGK Jurkat cells (
ADPGK activity was primarily described for thermophilic Archaea (38, 40). Notably, a secondary structure prediction for mammalian ADPGK reveals a high structural similarity to known secondary structures of thermostable archaeal ADPGK despite a low sequence homology (
Many cancers strictly depend on the constitutive activation of the NF-KB pathway (16). High intrinsic levels of ROS or Warburg phenotype are features of many malignancies (11,14,42). Therefore, ADPGK expression in cancer cells was investigated. T cell-originated cancers are rare in humans as compared to B cell malignancies. Particularly, CLL constitutes one of the most common leukemias with fatal prognosis (43). Moreover, CLL cells are endowed with enhanced NF-κB activity, glycolysis and high intrinsic ROS levels (15, 17, 43-45). Thus, ADPGK and GPD2 expression levels in malignant CLL cells and normal B cells were compared (Table 1).
As shown in
T cell activation is associated with a metabolic shift from mitochondrial respiration towards aerobic glycolysis (12). This so-called “Warburg phenotype” is a characteristic feature of fast proliferating normal but also of malignant cells (11,14). Previous work has shown, that proliferating T cells are characterized by a high TCR-triggered mitochondrial ROS production (1, 3). This mitochondria-generated oxidative signal contributes to NF-κB activation and, thus, stimulates proliferation and an inflammatory response. Interestingly, cancer cells often display an aerobic glycolytic phenotype and are endowed with high intrinsic ROS production and constitutive activation of the NF-κB pathway (14,16,18,42). In addition, up-regulation of glycolysis upon hyperglycemic or hypoxic conditions is known to increase mitochondrial ROS generation (18, 19, 21), while T cell activation depends on glucose uptake (9, 10). Thus, the metabolic analysis of T cell activation-induced mitochondrial ROS production may provide a molecular link connecting these different phenomena at the signaling level.
In the experiments described above it was shown that T cell activation-induced mitochondrial ROS production and gene expression depend on triggering of ADPGK, an archaeabacterial protein with so far unknown function in eukaryotes. ADPGK activation is accompanied by a rapid glucose uptake, down-regulation of mitochondrial oxygen consumption and deviation of glycolysis towards GPD shuttle, i.e. the Warburg-effect. In turn, the activation of respiratory chain-associated GPD2 leads to a hyper-reduction of ubiquinone and RET-mediated ROS release from complex I (
Strikingly, CLL cells, endowed with a high intrinsic ROS level and constitutive NF-κB activity (15,17), display enhanced ADPGK and GPD2 expression (
In general, immune cell activation is connected with an inflammatory scenario. The finding of enhanced ADPGK activity at a pro-inflammatory temperature underlines the importance of this novel protein in the NF-κB-mediated response. Moreover, close similarity between predicted secondary structure of human ADPGK and crystal structures of ADPGK proteins of thermophilic Archaea (
Cellular localization of ADPGK presents an interesting and yet unresolved issue. It has been previously suggested that ADP-mediated glucose phosphorylation constitutes a mechanism to preserve the intracellular ATP pool under ischemic or hypoxic conditions (38). ER-localization, however, indicates a more complex role for this protein. ADPGK could participate in metabolic pathways mediated by hexose-6-phosphate dehydrogenase (H6PD) (48) or glucose-6-phosphate phosphatase (G6PC3) (49), two gluconeogenetic enzymes also expressed highly in extrahepatic tissues. Glucose-6-phosphate/glucose recycling by G6PC3 has been recently demonstrated to be crucial for activation of human neutrophils (49). Alternatively, ADPGK-generated glucose-6-phosphate could fuel H6PD-derived NAPDH generation, and, thus influence the ER redox balance. Furthermore, in adipose, liver and muscle tissue H6PD-generated NADPH directly contributes to 11β-phydroxysteroid dehydrogenase type 1 (HSD11B1)-mediated pre-receptorial activation of glucocorticoids (48). Thus, ADPGK/H6PD/(HSD11B1) or ADPGK/G6PC3 pathways could participate in regulation of T cell activation and differentiation.
In conclusion, experimental evidence for an unexpected role for ADPGK as a novel regulator of T cell activation is provided. In addition, based on the identified mechanism of glycolytic flux-induced mitochondrial ROS release for T cells, a hypothesis connecting the Warburg phenotype with increased mitochondrial ROS levels and enhanced NF-κB signaling in fast proliferating cancer cells is proposed.
The invention will be further described by the following numbered paragraphs:
1. A compound capable of modulating (a) the biological activity of glycerol-3-phosphate dehydrogenase (GPD2) and/or ADP-dependent glucokinase (ADPGK) or (b) the expression of the gene encoding GPD2 or ADPGK for use in treating a disease (a) associated with aberrant cell proliferation or (b) of the immune system.
2. The compound according to paragraph 1 for the use according to paragraph 1, wherein said modulation is reduction or inhibition.
3. The compound according to paragraph 1 for the use according to paragraph 1, wherein said compound is an antisense oligonucleotide or siRNA reducing or inhibiting the expression of the gene encoding GPD2 and/or ADPGK.
4. The compound according to paragraph 1 for the use according to paragraph 1, wherein said compound is a compound reducing or inhibiting the biological activity of GPD2 and/or ADPGK.
5. The compound according to paragraph 4 for the use according to paragraph 1, wherein said compound is an antibody directed against ADPGK or a fragment thereof having the same specificity.
6. The compound according to paragraph 1 for the use according to paragraph 1, wherein said compound is an inactive version of GPD2 and/or ADPGK or a polynucleic acid encoding an inactive version of GPD2 and/or ADPGK.
7. The compound according to paragraph 1 for the use according to paragraph 1, wherein the disease associated with aberrant cell proliferation is a neoplasm and/or the disease of the immune system is an autoimmune disease or Graft-versus-Host-Disease (GvHD).
8. The compound according to paragraph 1 for the use according to paragraph 7, wherein the neoplasm to be treated shows GPD2 and/or ADPGK (over)expression, preferably wherein the neoplasm to be treated is B cell chronic lymphocytic leukemia (CLL) or a tumor showing enhanced NF-KB levels.
9. The compound according to paragraph 1 for the use according to paragraph 1, wherein said modulation is activation, preferably wherein said activation is an increase of gene expression.
10. The compound according to paragraph 1 for the use according to paragraph 9, wherein said disease of the immune system is low immunity or acquired immune deficiency syndrome.
11. The compound according to paragraph 1 for the use according to paragraph 1, wherein said disease is rheumatism, Lupus erythematodes, Psoriasis, atopic dermatitis, multiple sclerosis, or diabetes.
12. A method for identifying a compound capable of modulating the biological activity of GPD2 or ADPGK or the expression of the gene encoding GPD2 or ADPG, comprising the steps of:
13. The method of paragraph 12, wherein the increase or reduction of the biological activity of GPD2 or ADPGK is determined by comparison to a test system characterized by the absence of said test compound.
14. A method of selecting a therapy modality for a patient afflicted with a disease as characterized in paragraph 1, comprising
15. The method of paragraph 14, wherein the level of ADPGK and/or GPD2 is determined (a) on the protein level using an antibody that specifically binds to GPD2 or ADPGK or (b) by assaying a biological activity of GPD2 or ADPGK.
Having thus described in detail preferred embodiments of the present invention, it is to be understood that the invention defined by the above paragraphs is not to be limited to particular details set forth in the above description as many apparent variations thereof are possible without departing from the spirit or scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 11004729.7 | Jun 2011 | EP | regional |
This application is a continuation of U.S. application Ser. No. 14/099,466 filed Dec. 6, 2013, which is a continuation-in-part of International Patent Application No. PCT/EP2012/002444, filed Jun. 8, 2012, published as WO 2012/167944 on Dec. 13, 2012, and claims priority to EP 11004729.7, filed Jun. 9, 2011. The foregoing applications, and all documents cited therein or during their prosecution (“appln cited documents”) and all documents cited or referenced in the appln cited documents, and all documents cited or referenced herein (“herein cited documents”), and all documents cited or referenced in herein cited documents, together with any manufacturer's instructions, descriptions, product specifications, and product sheets for any products mentioned herein or in any document incorporated by reference herein, are hereby incorporated herein by reference, and may be employed in the practice of the invention. More specifically, all referenced documents are incorporated by reference to the same extent as if each individual document was specifically and individually indicated to be incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14099466 | Dec 2013 | US |
| Child | 14957724 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2012/002444 | Jun 2012 | US |
| Child | 14099466 | US |
