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1.
Neurooncol Adv ; 4(1): vdac101, 2022.
Article in English | MEDLINE | ID: mdl-35875690

ABSTRACT

Background: Chemotherapy-induced peripheral neuropathy represents a major impairment to the quality of life of cancer patients and is one of the most common dose-limiting adverse effects of cancer treatment. Despite its prevalence, no effective treatment or prevention strategy exists. We have previously provided genetic evidence that the NAD+-dependent deacetylase, SIRT2, protects against cisplatin-induced peripheral neuronal cell death and neuropathy by enhancing nucleotide excision repair. In this study, we aimed to examine whether pharmacologic activation of SIRT2 would provide effective prevention and treatment of cisplatin-induced peripheral neuropathy (CIPN) without compromising tumor cell cytotoxic response to cisplatin. Methods: Using von Frey and dynamic hot plate tests, we studied the use of nicotinamide riboside (NR) to prevent and treat CIPN in a mouse model. We also performed cell survival assays to investigate the effect of NAD+ supplementation on cisplatin toxicity in neuronal and cancer cells. Lewis lung carcinoma model was utilized to examine the effect of NR treatment on in vivo cisplatin tumor control. Results: We show that NR, an NAD+ precursor and pharmacologic activator of SIRT2, effectively prevents and alleviates CIPN in mice. We present in vitro and in vivo genetic evidence to illustrate the specific dependence on SIRT2 of NR-mediated CIPN mitigation. Importantly, we demonstrate that NAD+ mediates SIRT2-dependent neuroprotection without inhibiting cisplatin cytotoxic activity against cancer cells. NAD+ may, in fact, further sensitize certain cancer cell types to cisplatin. Conclusions: Together, our results identify SIRT2-targeted activity of NR as a potential therapy to alleviate CIPN, the debilitating and potentially permanent toxicity.

2.
Metab Brain Dis ; 36(5): 751-765, 2021 06.
Article in English | MEDLINE | ID: mdl-33651273

ABSTRACT

Pyruvate kinase (PK) catalyzes the last irreversible reaction of glycolysis pathway, generating pyruvate and ATP, from Phosphoenol Pyruvate (PEP) and ADP precursors. In mammals, four different tissue-specific isoforms (M1, M2, L and R) of PK exist, which are translated from two genes (PKL and PKR). PKM2 is the highly expressed isoform of PK in cancers, which regulates the aerobic glycolysis via reprogramming cancer cell's metabolic pathways to provide an anabolic advantage to the tumor cells. In addition to the established role of PKM2 in aerobic glycolysis of multiple cancer types, various recent findings have highlighted the non-metabolic functions of PKM2 in brain tumor development. Nuclear PKM2 acts as a co-activator and directly regulates gene transcription. PKM2 dependent transactivation of various oncogenic genes is instrumental in the progression and aggressiveness of Glioblastoma Multiforme (GBM). Also, PKM2 acts as a protein kinase in histone modification which regulates gene expression and tumorigenesis. Ongoing research has explored novel regulatory mechanisms of PKM2 and its association in GBM progression. This review enlists and summarizes the metabolic and non-metabolic roles of PKM2 at the cellular level, and its regulatory function highlights the importance of the nuclear functions of PKM2 in GBM progression, and an emerging role of PKM2 as novel cancer therapeutics.


Subject(s)
Brain Neoplasms/metabolism , Brain/metabolism , Glioblastoma/metabolism , Pyruvate Kinase/metabolism , Brain/pathology , Brain Neoplasms/pathology , Glioblastoma/pathology , Glycolysis/physiology , Humans
3.
Metab Brain Dis ; 33(4): 1307-1326, 2018 08.
Article in English | MEDLINE | ID: mdl-29721771

ABSTRACT

Maintaining genomic integrity is essential for cell survival and viability. Reactive oxygen species (ROS) overproduction results in oxidative stress leading to the genomic instability via generation of small base lesions in DNA and these unrepaired DNA damages lead to various cellular consequences including cancer. Recent data support the concept "oxidative stress is an indispensable participant in fostering proliferation, survival, and migration" in various cancer cell types including glioblastoma cells. In this study we demonstrate that treatment of non-cytotoxic doses of oxidants such as amyloid beta [Aß(25-35)] peptide, glucose oxidase (GO), and hydrogen peroxide (H2O2) for 24 h and 48 h time points found to increase the expression level and activity of a multifunctional enzyme Apurinic/apyrimidinic endonuclease (APE1), a key enzyme of base excision repair (BER) pathway which takes care of base damages; and also resulted in modulation in the expression levels of downstream BER-pathway enzymes viz. PARP-1, XRCC1, DNA polß, and ligase IIIα was observed upon oxidative stress in C6 and U-87 MG cells. Oxidants treatment to the C6 and U-87 MG cells also resulted in an elevation in the intracellular expression of glycolytic pathway enzyme Pyruvate kinase M2 (PKM2) and the metastasis inducer protein Ectonucleotide pyrophosphatase/phosphodiesterase 2 (ENPP2) as analyzed using Western blotting and Immunofluorescence microscopic studies. Our study also reports that oxidative stress induced for 24 h and 48 h in C6 and U-87 MG cells resulted in extracellular secretion of APE1 and ENPP2 as analyzed using Western blotting in conditioned media. However, the biological significance of extracellular secreted APE1 remains elusive. Oxidative stress also elevated the ENPP2's LysoPLD activity in conditioned media of C6 and U-87 MG cells. Our results also demonstrate that oxidative stress affects the expression level and localization of APE1, PKM2, and ENPP2 in C6 and U-87 MG cells. As evidenced by the colocalization pattern at 24 h and 48 h time points, it can be attributed that oxidative stress mediates crosstalk between APE1, PKM2, and ENPP2. In addition, when C6 and U-87 MG cells were treated with lysophosphatidic acid (LPA), a bioactive lipid that negatively regulates ENPP2's LysoPLD activity at 10 µM concentration, demonstrated strong migratory potential in C6 and U-87 MG cells, and also induced migration upon oxidative stress. Altogether, the findings demonstrate the potential of C6 and U-87 MG cells to utilize three proteins viz. APE1, PKM2, and ENPP2 towards migration and survival of gliomas. Thus the knowledge on oxidative stress induced APE1's interaction with PKM2 and ENPP2 opens a new channel for the therapeutic target(s) for gliomas.


Subject(s)
Carrier Proteins/metabolism , DNA-(Apurinic or Apyrimidinic Site) Lyase/metabolism , Glioblastoma/metabolism , Membrane Proteins/metabolism , Neoplasm Invasiveness/pathology , Oxidative Stress/physiology , Phosphoric Diester Hydrolases/metabolism , Thyroid Hormones/metabolism , Animals , Cell Line, Tumor , Glioblastoma/pathology , Humans , Rats , Signal Transduction/physiology , Thyroid Hormone-Binding Proteins
4.
Arch Pharm (Weinheim) ; 351(6): e1800023, 2018 Jun.
Article in English | MEDLINE | ID: mdl-29737542

ABSTRACT

The design and synthesis of dihydropyrazolo[1,5-c]quinazolines (1a-h) as human topoisomerase II (TopoII) catalytic inhibitors are reported. The compounds were investigated for their antiproliferative activity against the C6 rat glial cell line. Two compounds, 1b and 1h, were found to be potent cytotoxic agents against glioma cells and exerted selective TopoII inhibitory activity. Furthermore, the compounds induced alterations in reactive oxygen species levels as measured by DCFDA assay and were found to induce cell cycle arrest at the G1 phase at lower concentrations and profound apoptosis at higher concentrations. The interaction of selected investigational molecules with TopoII was further corroborated by molecular modeling.


Subject(s)
Antineoplastic Agents/pharmacology , Glioma/drug therapy , Quinazolines/pharmacology , Topoisomerase II Inhibitors/pharmacology , Animals , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/chemistry , Apoptosis/drug effects , Cell Line, Tumor , DNA Topoisomerases, Type II/drug effects , DNA Topoisomerases, Type II/metabolism , Dose-Response Relationship, Drug , G1 Phase Cell Cycle Checkpoints/drug effects , Glioma/enzymology , Humans , Models, Molecular , Quinazolines/chemical synthesis , Quinazolines/chemistry , Rats , Reactive Oxygen Species/metabolism , Topoisomerase II Inhibitors/chemical synthesis , Topoisomerase II Inhibitors/chemistry
5.
Metab Brain Dis ; 32(5): 1705-1716, 2017 10.
Article in English | MEDLINE | ID: mdl-28676971

ABSTRACT

Glial cells protect themselves from the elevated reactive oxygen species (ROS) via developing unusual mechanisms to maintain the genomic stability, and reprogramming of the cellular antioxidant system to cope with the adverse effects. In the present study non-cytotoxic dose of oxidants, H2O2 (100 µM) and GO (10 µU/ml) was used to induce moderate oxidative stress via generating ROS in human glioblastoma cell line U-87 MG cells, which showed a marked increase in the antioxidant capacity as studied by measuring the modulation in expression levels and activities of superoxide dismutase (SOD1 and SOD2) and catalase (CAT) enzymes, and the GSH content. However, pretreatment (3 h) of Curcumin and Quercetin (10 µM) followed by the treatment of oxidants enhanced the cell survival, and the levels/activities of the antioxidants studied. Oxidative stress also resulted in an increase in the nitrite levels in the culture supernatants, and further analysis by immunocytochemistry showed an increase in iNOS expression. In addition, phytochemical pretreatment decreased the nitrite level in the culture supernatants of oxidatively stressed U-87 MG cells. Elevated ROS also increased the expression of COX-2 and APE1 enzymes and pretreatment of Curcumin and Quercetin decreased COX-2 expression and increased APE1 expression in the oxidatively stressed U-87 MG cells. The immunocytochemistry also indicates for APE1 enhanced stress-dependent subcellular localization to the nuclear compartment, which advocates for enhanced DNA repair and redox functions of APE1 towards survival of U-87 MG cells. It can be concluded that intracellular oxidants activate the key enzymes involved in antioxidant mechanisms, NO-dependent survival mechanisms, and also in the DNA repair pathways for glial cell survival in oxidative-stress micro-environment.


Subject(s)
Antioxidants/metabolism , Brain Neoplasms/metabolism , Glioblastoma/metabolism , Glucose Oxidase/metabolism , Hydrogen Peroxide/metabolism , Antioxidants/pharmacology , Brain Neoplasms/pathology , Catalase/metabolism , Cell Line, Tumor , Cell Survival , Cyclooxygenase 2/biosynthesis , DNA-(Apurinic or Apyrimidinic Site) Lyase/biosynthesis , Glioblastoma/pathology , Glutathione/metabolism , Humans , Nitric Oxide Synthase Type II/biosynthesis , Superoxide Dismutase/metabolism , Superoxide Dismutase-1/metabolism
6.
J Med Chem ; 57(24): 10241-56, 2014 Dec 26.
Article in English | MEDLINE | ID: mdl-25280182

ABSTRACT

The apurinic/apyrimidinic endonuclease 1/redox effector factor 1 (APE1/Ref-1) is a multifunctional enzyme involved in DNA repair and activation of transcription factors through its redox function. The evolutionarily conserved C- and N-termini are involved in these functions independently. It is also reported that the activity of APE1/Ref-1 abruptly increases several-fold in various human cancers. The control over the outcomes of these two functions is emerging as a new strategy to combine enhanced DNA damage and chemotherapy in order to tackle the major hurdle of increased cancer cell growth and proliferation. Studies have targeted these two domains individually for the design and development of inhibitors for APE1/Ref-1. Here, we have made, for the first time, an attempt at a comparative analysis of APE1/Ref-1 inhibitors that target both DNA repair and redox activities simultaneously. We further discuss their scope and limitations with respect to the development of potential anticancer agents.


Subject(s)
Antineoplastic Agents/pharmacology , DNA Repair/drug effects , DNA-(Apurinic or Apyrimidinic Site) Lyase/antagonists & inhibitors , Drug Design , Neoplasms/drug therapy , Humans , Oxidation-Reduction
7.
Exp Mol Med ; 46: e106, 2014 Jul 18.
Article in English | MEDLINE | ID: mdl-25033834

ABSTRACT

Apurinic/apyrimidinic endonuclease 1 (APE1) is a multifunctional enzyme involved in the base excision repair (BER) pathway, which repairs oxidative base damage caused by endogenous and exogenous agents. APE1 acts as a reductive activator of many transcription factors (TFs) and has also been named redox effector factor 1, Ref-1. For example, APE1 activates activator protein-1, nuclear factor kappa B, hypoxia-inducible factor 1α, paired box gene 8, signal transducer activator of transcription 3 and p53, which are involved in apoptosis, inflammation, angiogenesis and survival pathways. APE1/Ref-1 maintains cellular homeostasis (redox) via the activation of TFs that regulate various physiological processes and that crosstalk with redox balancing agents (for example, thioredoxin, catalase and superoxide dismutase) by controlling levels of reactive oxygen and nitrogen species. The efficiency of APE1/Ref-1's function(s) depends on pairwise interaction with participant protein(s), the functions regulated by APE1/Ref-1 include the BER pathway, TFs, energy metabolism, cytoskeletal elements and stress-dependent responses. Thus, APE1/Ref-1 acts as a 'hub-protein' that controls pathways that are important for cell survival. In this review, we will discuss APE1/Ref-1's versatile nature in various human etiologies, including neurodegeneration, cancer, cardiovascular and other diseases that have been linked with alterations in the expression, subcellular localization and activities of APE/Ref-1. APE1/Ref-1 can be targeted for therapeutic intervention using natural plant products that modulate the expression and functions of APE1/Ref-1. In addition, studies focusing on translational applications based on APE1/Ref-1-mediated therapeutic interventions are discussed.


Subject(s)
DNA-(Apurinic or Apyrimidinic Site) Lyase/metabolism , Molecular Targeted Therapy , Neoplasms/drug therapy , Neoplasms/metabolism , Neurodegenerative Diseases/drug therapy , Neurodegenerative Diseases/metabolism , Phytochemicals/therapeutic use , Animals , DNA Damage , DNA Repair , DNA-(Apurinic or Apyrimidinic Site) Lyase/analysis , DNA-(Apurinic or Apyrimidinic Site) Lyase/genetics , Humans , Molecular Targeted Therapy/methods , Neoplasms/genetics , Neurodegenerative Diseases/genetics , Oxidative Stress , Phytochemicals/pharmacology , Polymorphism, Genetic , Protein Interaction Maps
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