Molecular editing of NSC-666719 enabling discovery of benzodithiazinedioxide-guanidines as anticancer agents.

DNA polymerase ß (Polß) is crucial for the base excision repair (BER) pathway of DNA damage repair and is an attractive target for suppressing tumorigenesis as well as chemotherapeutic intervention of cancer. In this study, a unique strategy of scaffold-hopping-based molecular editing of a bioactive agent NSC-666719 was investigated, which led to the development of new molecular motifs with Polß inhibitory activity. NSC compound and its analogs (two series) were prepared, focusing on pharmacophore-based molecular diversity. Most compounds showed higher activities than the parent NSC-666719 and exhibited effects on apoptosis. The inhibitory activity of Polß was evaluated in both in vitro reconstituted and in vivo intact cell systems. Compound 10e demonstrated significant Polß interaction and inhibition characteristics, including direct, non-covalent, reversible, and comparable binding affinity. The investigated approach is useful, and the discovered novel analogs have a high potential for developing as anticancer therapeutics.

Design, synthesis, and anticancer activity of some novel 1H-benzo[d]imidazole-5-carboxamide derivatives as fatty acid synthase inhibitors.

Multiple malignancies exhibit aberrant FASN expression, associated with enhanced de novo lipogenesis to meet the metabolic demands of rapidly proliferating tumour cells. Furthermore, elevated FASN expression has been linked to tumour aggressiveness and poor prognosis in a variety of malignant tumours, making FASN is an attractive target for anticancer drug discovery. Herein, we report the de novo design and synthesis of (2-(2-hydroxyphenyl)-1H-benzo[d]imidazol-5-yl)(piperazin-1-yl)methanone derivatives as novel FASN inhibitors with potential therapeutic applications in breast and colorectal cancers. Twelve (2-(2-hydroxyphenyl)-1H-benzo[d]imidazol-5-yl)(piperazin-1-yl)methanone derivatives (CTL) were synthesized and evaluated for FASN inhibition and cytotoxicity against colon cancer (HCT-116, Caco-2 cell lines), breast cancer (MCF-7 cell line) and normal cell line (HEK-293). Compounds CTL-06 and CTL-12 were chosen as the most promising lead molecules based on FASN inhibition and selective cytotoxicity profiles against colon and breast cancer cell lines. Compounds CTL-06 and CTL-12 demonstrate promising FASN inhibitory activity at IC50 of 3 ± 0.25 µM and 2.5 ± 0.25 µM when compared to the FASN inhibitor orlistat, which has an IC50 of 13.5 ± 1.0 µM. Mechanistic investigations on HCT-116 revealed that CTL-06 and CTL-12 treatment led to cell cycle arrest in Sub-G1/S phase along with apoptosis induction. Western blot studies indicated that CTL-06 and CTL-12 inhibited FASN expression in a dose-dependent manner. CTL-06 and CTL-12 treatment of HCT-116 cells enhanced caspase-9 expression in a dose-dependent manner, while upregulating proapoptotic marker Bax and downregulating antiapoptotic Bcl-xL. Molecular docking experiments of CTL-06 and CTL-12 with FASN enzyme revealed the mode of binding of these analogues in the KR domain of the enzyme.

Exploration of Benzo[b]carbazole-6,11-diones as anticancer agents: Synthesis and studies of hTopoIIα inhibition and apoptotic effects.

Two series of (hetero)arylamino-naphthoquinones and benzo-fused carbazolequinones were considered for study with the rationale that related structural motifs are present in numerous drugs, clinical trial agents, natural products and hTopoIIα inhibitors. Total 42 compounds were synthesized by reactions including dehydrogenative CN and Pd-catalyzed CC bond forming transformations. These compounds were screened against numerous cancer cells including highly metastatic one (MCF-7, MDA-MB-231, H-357 and HEK293T), and normal cells (MCF 10A). Some of the active compounds were evaluated for clonogenic cell survival and apoptotic effects in cancer cells (DAPI nuclear staining, Comet assay, Annexin-V-FITC/PI dual staining, flow cytometry, and western blot analysis with relevant proteins). All compounds were tested for hTopoIIα inhibitory activity. The investigated series compounds showed important properties like significant apoptotic antiproliferation in cancer cells with cell cycle arrest at S-phase and downregulation of NF- κß signaling cascade, relatively less cytotoxicity to normal cells, and hTopoIIα inhibition with more efficiency compared to an anticancer drug etoposide.

Anti-Cancer Stem Cells Potentiality of an Anti-Malarial Agent Quinacrine: An Old Wine in a New Bottle.

Quinacrine (QC) is a tricyclic compound and a derivative of 9-aminoacridine. It has been widely used to treat malaria and other parasitic diseases since the last century. Interestingly, studies have revealed that it also displays anti-cancer activities. Here, we have discussed the anti-cancer mechanism of QC along with its potentiality to specifically target cancer stem cells. The anti-cancer action of this drug includes DNA intercalation, inhibition of DNA repair mechanism, prevention of cellular growth, cell cycle arrest, inhibition of DNA and RNA polymerase activity, induction of autophagy, promotion of apoptosis, deregulation of cell signaling in cancer cells and cancer stem cells, inhibition of metastasis and angiogenesis. In addition, we have also emphasized on the synergistic effect of this drug with other potent chemotherapeutic agents and mentioned its different applications in anti-cancer therapy.

Therapeutic prospective of plant-induced silver nanoparticles: application as antimicrobial and anticancer agent.

Green synthesis approach for nanoparticle is environmental friendly, non-hazardous and the nanoparticles have shown enhanced biocompatibility for application in healthcare. Previous reviews have mentioned about green synthesis methods for nanoparticles and their biological activities. This review not only covers the general information about green synthesis of silver nanoparticles and characterization, but also focused on recent uses of various medicinal and nonmedical plants based AgNPs synthesis and their broad-spectrum antimicrobial and anticancer activities. In addition, this review emphasizes on elaborating underlying mechanism of anti-pathogenic microbial and anticancer activities of plant based AgNPs. Thus, present article provides a comprehensive analysis of plant-mediated synthesis of AgNPs and their potential applications in biomedical field including their mode of action and challenges in a single window.

A Chemosensitizer Drug: Disulfiram Prevents Doxorubicin-Induced Cardiac Dysfunction and Oxidative Stress in Rats.

In the present study, the preventive effects of orally administered disulfiram (DS) against the doxorubicin (DOX)-induced cardiotoxicity were investigated in rats. DS was orally administered for 7 days at doses of 2, 10, and 50 mg/kg/day. DOX (30 mg/kg) was intraperitoneally administered on the 5th day of the initiation of DS treatment. Within 48 h of injection, DOX treatment significantly altered ECG, elevated the ST height, and increased the QT and QRS intervals. It reduced the cardiac levels of injury markers like creatine kinase isoenzyme-MB and lactate dehydrogenase. DOX elevated the serum levels of SGOT and nitric oxide. Its injection significantly induced lipid peroxidation in the cardiac tissue and reduced the activities of innate antioxidants like super oxide dismutase, catalase, and reduced glutathione in the cardiac tissue. DOX treatment raised the TNF-α level and caused histological alterations in the myocardium like neutrophil infiltrations, myonecrosis, and edema. Pre-treatment of rats with DS (2, 10, and 50 mg/kg p. o. for 7 days) prevented the ECG changes, minimized oxidative stress, and normalized the biochemical indicators of the DOX-induced cardiotoxicity. DS also protected rat heart from DOX-induced histological alterations. Recently, DS is reported to exert chemosensitization of cancer cells. Our in vitro investigation using MCF7 cell line revealed that DS reverses the DOX-induced suppression of NF-κB and Nrf2 expression. These findings about the protective activity of DS against the DOX-induced cardiotoxicity warrant a detailed investigation on its utility as an adjunct therapy to cancer chemotherapy.

Mild cold induced thermogenesis: are BAT and skeletal muscle synergistic partners?

There are two well-described thermogenic sites; brown adipose tissue (BAT) and skeletal muscle, which utilize distinct mechanisms of heat production. In BAT, mitochondrial metabolism is the molecular basis of heat generation, while it serves only a secondary role in supplying energy for thermogenesis in muscle. Here, we wanted to document changes in mitochondrial ultrastructure in these two tissue types based upon adaptation to mild (16°C) and severe (4°C) cold in mice. When reared at thermoneutrality (29°C), mitochondria in both tissues were loosely packed with irregular cristae. Interestingly, adaptation to even mild cold initiated ultrastructural remodeling of mitochondria including acquisition of more elaborate cristae structure in both thermogenic sites. The shape of mitochondria in the BAT remained mostly circular, whereas the intermyofibrilar mitochondria in the skeletal muscle became more elongated and tubular. The most dramatic remodeling of mitochondrial architecture was observed upon adaptation to severe cold. In addition, we report cold-induced alteration in levels of humoral factors: fibroblast growth factor 21 (FGF21), IL1α, peptide YY (PYY), tumor necrosis factor α (TNFα), and interleukin 6 (IL6) were all induced whereas both insulin and leptin were down-regulated. In summary, adaptation to cold leads to enhanced cristae formation in mitochondria in skeletal muscle as well as the BAT. Further, the present study indicates that circulating cytokines might play an important role in the synergistic recruitment of the thermogenic program including cross-talk between muscle and BAT.

Scaffold-Hopping of Aurones: 2-Arylideneimidazo[1,2-a]pyridinones as Topoisomerase IIα-Inhibiting Anticancer Agents.

Scaffold-hopping of bioactive natural product aurones has been studied for the first time. 2-Arylideneimidazo[1,2-a]pyridinones as potential topoisomerase IIα (hTopoIIα)-targeting anticancer compounds were considered. A multifunctional activator, polyphosphoric acid, enabled to realize a cascade reaction of 2-aminopyridine with 2,3-epoxyesters toward synthesis of 2-arylideneimidazo[1,2-a]pyridinones. Most of the compounds exhibited hTopoIIα-selective poison activity with efficiency more than etoposide and DNA-binding property, while not interacting with hTopo I. The compounds showed pronounced antiproliferative activities in nanomolar range with relatively poor toxicity to normal cells, inhibition of invasiveness, and apoptotic effect. The activities for inhibition of tubulin assembly, CDK1 and pCDK1, were also observed. Interestingly, the hTopoIIα inhibitory (in vitro and ex vivo studies) and antiproliferative activities of representative potent compounds were found to be manifold higher compared to corresponding parent aurones bearing alike substitutions, indicating the importance of such scaffold-hopping strategy in medicinal chemistry research.

In vivo and in vitro protective effects of omeprazole against neuropathic pain.

Apart from reducing the acid secretion, omeprazole inhibits activation of the nuclear factor-κB, release of inflammatory cytokines, and chemotaxis of neutrophils. These mechanisms prompted us to evaluate antineuropathic effect of omeprazole in the chronic constriction injury (CCI)-induced rat model of neuropathic pain and LPS mediated ROS-induced U-87 cells. Omeprazole at 50 mg/kg/day/oral for 14 days significantly reduced the intensity of neuropathic pain estimated as paw withdrawal latency, withdrawal pressure threshold and restored the motor nerve conduction velocity in the constricted nerve, when compared with respective groups. The histological findings revealed the protective effect of omeprazole against the CCI-induced damage. Omeprazole significantly decreased the levels of tumor necrosis factor (TNF-α), interleukin-1ß (IL-1ß) and interleukin-6 (IL-6) as compared to their respective control groups. It also reduced the oxidative stress by up regulating the SOD, catalase activity and decreasing MDA content. Similarly, in-vitro study, LPS mediated ROS-induced U-87 cells, omeprazole reduced the oxidative stress as well as the release of TNF-α, IL-1ß and IL-6. Altogether, these results suggest that, neuroprotective effect of omeprazole is mediated through preventing release of proinflammatory cytokines, augmenting endogenous anti-oxidant defense system, and maintain the structural integrity of sciatic nerve from the CCI-induced structural damage and inflammatory changes.

Scaffold-hopping of bioactive flavonoids: Discovery of aryl-pyridopyrimidinones as potent anticancer agents that inhibit catalytic role of topoisomerase IIα.

A strategy of scaffold-hopping of bioactive natural products, flavones and isoflavones, leading to target-based discovery of potent anticancer agents has been reported for the first time. Scaffold-hopped flavones, 2-aryl-4H-pyrido[1,2-a]pyrimidin-4-ones and the scaffold-hopped isoflavones, 3-aryl-pyrido[1,2-a]pyrimidin-4-ones were synthesized via Pd-catalyzed activation-arylation methods. Most of the compounds were found to exhibit pronounced human topoisomerase IIα (hTopoIIα) inhibitory activities and several compounds were found to be more potent than etoposide (a hTopoIIα-inhibiting anticancer drug). These classes of compounds were found to be hTopoIIα-selective catalytic inhibitors while not interfering with topoisomerase I and interacted with DNA plausibly in groove domain. Cytotoxicities against various cancer cells, low toxicity in normal cells, and apoptotic effects were observed. Interestingly, compared to parent flavones/isoflavones, their scaffold-hopped analogs bearing alike functionalities showed significant/enhanced hTopoIIα-inhibitory and cytotoxic properties, indicating the importance of a natural product-based scaffold-hopping strategy in the drug discovery.

Pentacyclic Triterpenoids Inhibit IKKß Mediated Activation of NF-κB Pathway: In Silico and In Vitro Evidences.

Pentacyclic Triterpenoids (PTs) and their analogues as well as derivatives are emerging as important drug leads for various diseases. They act through a variety of mechanisms and a majority of them inhibit the nuclear factor kappa-beta (NF-κB) signaling pathway. In this study, we examined the effects of the naturally occurring PTs on IκB kinase-ß (IKKß), which has great scientific relevance in the NF-κB signaling pathway. On virtual screening, 109 PTs were screened through the PASS (prediction of activity spectra of substances) software for prediction of NF-κB inhibitory activity followed by docking on the NEMO/IKKß association complex (PDB: 3BRV) and testing for compliance with the softened Lipinski's Rule of Five using Schrodinger (LLC, New York, USA). Out of the projected 45 druggable PTs, Corosolic Acid (CA), Asiatic Acid (AA) and Ursolic Acid (UA) were assayed for IKKß kinase activity in the cell free medium. The UA exhibited a potent IKKß inhibitory effect on the hotspot kinase assay with IC50 of 69 µM. Whereas, CA at 50 µM concentration markedly reduced the NF-κB luciferase activity and phospho-IKKß protein expressions. The PTs tested, attenuated the expression of the NF-κB cascade proteins in the LPS-stimulated RAW 264.7 cells, prevented the phosphorylation of the IKKα/ß and blocked the activation of the Interferon-gamma (IFN-γ). The results suggest that the IKKß inhibition is the major mechanism of the PTs-induced NF-κB inhibition. PASS predictions along with in-silico docking against the NEMO/IKKß can be successfully applied in the selection of the prospective NF-κB inhibitory downregulators of IKKß phosphorylation.

Switch in Site of Inhibition: A Strategy for Structure-Based Discovery of Human Topoisomerase IIα Catalytic Inhibitors.

A study of structure-based modulation of known ligands of hTopoIIα, an important enzyme involved in DNA processes, coupled with synthesis and in vitro assays led to the establishment of a strategy of rational switch in mode of inhibition of the enzyme's catalytic cycle. 6-Arylated derivatives of known imidazopyridine ligands were found to be selective inhibitors of hTopoIIα, while not showing TopoI inhibition and DNA binding. Interestingly, while the parent imidazopyridines acted as ATP-competitive inhibitors, arylated derivatives inhibited DNA cleavage similar to merbarone, indicating a switch in mode of inhibition from ATP-hydrolysis to the DNA-cleavage stage of catalytic cycle of the enzyme. The 6-aryl-imidazopyridines were relatively more cytotoxic than etoposide in cancer cells and less toxic to normal cells. Such unprecedented strategy will encourage research on "choice-based change" in target-specific mode of action for rapid drug discovery.

Kaposi sarcoma herpes virus latency associated nuclear antigen protein release the G2/M cell cycle blocks by modulating ATM/ATR mediated checkpoint pathway.

The Kaposi's sarcoma-associated herpesvirus infects the human population and maintains latency stage of viral life cycle in a variety of cell types including cells of epithelial, mesenchymal and endothelial origin. The establishment of latent infection by KSHV requires the expression of an unique repertoire of genes among which latency associated nuclear antigen (LANA) plays a critical role in the replication of the viral genome. LANA regulates the transcription of a number of viral and cellular genes essential for the survival of the virus in the host cell. The present study demonstrates the disruption of the host G2/M cell cycle checkpoint regulation as an associated function of LANA. DNA profile of LANA expressing human B-cells demonstrated the ability of this nuclear antigen in relieving the drug (Nocodazole) induced G2/M checkpoint arrest. Caffeine suppressed nocodazole induced G2/M arrest indicating involvement of the ATM/ATR. Notably, we have also shown the direct interaction of LANA with Chk2, the ATM/ATR signalling effector and is responsible for the release of the G2/M cell cycle block.

Epstein-Barr virus nuclear antigen 3C interact with p73: Interplay between a viral oncoprotein and cellular tumor suppressor.

The p73 protein has structural and functional homology with the tumor suppressor p53, which plays an important role in cell cycle regulation, apoptosis, and DNA repair. The p73 locus encodes both a tumor suppressor (TAp73) and a putative oncogene (ΔNp73). p73 May play a significant role in p53-deficient lymphomas infected with Epstein-Barr virus (EBV). EBV produces an asymptomatic infection in the majority of the global population, but it is associated with several human B-cell malignancies. The EBV-encoded Epstein-Barr virus nuclear antigen 3C (EBNA3C) is thought to disrupt the cell cycle checkpoint by interacting directly with p53 family proteins. Doxorubicin, a commonly used chemotherapeutic agent, induces apoptosis through p53 and p73 signaling such that the lowΔNp73 level promotes the p73-mediated intrinsic pathway of apoptosis. In this report, we investigated the mechanism by which EBV infection counters p73α-induced apoptosis through EBNA3C.

Structural elaboration of a natural product: identification of 3,3'-diindolylmethane aminophosphonate and urea derivatives as potent anticancer agents.

An approach involving rational structural elaboration of the biologically active natural product diindolylmethane (DIM) with the incorporation of aminophosphonate and urea moieties toward the discovery of potent anticancer agents was considered. A four-step approach for the synthesis of DIM aminophosphonate and urea derivatives was established. These novel compounds showed potent anticancer activities in two representative kidney and colon cancer cell lines, low toxicity to normal cells, higher potency than the parent natural product DIM and etoposide, and potent inhibition of cancer cell migration. Biophysical and immunological studies, including DAPI nuclear staining, western blot analysis with apoptotic protein markers, flow cytometry, immunocytochemistry, and comet assays of the two most potent compounds revealed good efficacies in apoptosis and DNA damage. It was found that down-regulation of nuclear factor κB (NF-κB p65) could be an important mode of action in apoptosis, and the two most potent derivatives were found to be more potent than parent compound DIM in the down-regulation of NF-κB. Our results show the importance of structural elaboration of DIM by rational incorporation of aminophosphonate and urea moieties to produce potent anticancer agents; they also suggest that this approach using other structurally simple bioactive natural products as scaffolds holds promise for future drug discovery and development.

Indenoindolone derivatives as topoisomerase II-inhibiting anticancer agents.

Based on known heterocyclic topoisomerase II inhibitors and anticancer agents, various indenoindolone derivatives were predicted as potential topoisomerase II-inhibiting anticancer agents. They are hydrazones, (thio)semicarbazones, and oximes of indenoindolones, and indenoindolols. These derivatives with suitable substitutions exhibited potent specific inhibition of human DNA TopoIIα while not showing inhibition of topoisomerase I and DNA intercalation, despite the fact that parent indenoindolones are known poor/moderate inhibitors of topoisomerase II. The potent topoisomerase II inhibitor indenoindolone derivatives exhibited good anticancer activities compared to etoposide and 5-fluorouracil, and relatively low toxicity to normal cells. These derivatizations of indenoindolones were found to result in enhancement of anticancer activities.

Lycopene synergistically enhances quinacrine action to inhibit Wnt-TCF signaling in breast cancer cells through APC.

We previously reported that quinacrine (QC) has anticancer activity against breast cancer cells. Here, we examine the mechanism of action of QC and its ability to inhibit Wnt-TCF signaling in two independent breast cancer cell lines. QC altered Wnt-TCF signaling components by increasing the levels of adenomatous polyposis coli (APC), DAB2, GSK-3ß and axin and decreasing the levels of ß-catenin, p-GSK3ß (ser 9) and CK1. QC also reduced the activity of the Wnt transcription factor TCF/LEF and its downstream targets cyclin D1 and c-MYC. Using a luciferase-based Wnt-TCF transcription factor assay, it was shown that APC levels were inversely associated with TCF/LEF activity. Induction of apoptosis and DNA damage was observed after treatment with QC, which was associated with increased expression of APC. The effects induced by QC depend on APC because the inhibition of Wnt-TCF signaling by QC is lost in APC-knockdown cells, and consequently, the extent of apoptosis and DNA damage caused by QC is reduced compared with parental cells. Because we previously showed that QC inhibits topoisomerase, we examined the effect of another topoisomerase inhibitor, etoposide, on Wnt signaling. Interestingly, etoposide treatment also reduced TCF/LEF activity, ß-catenin and cyclin D1 levels commensurate with induction of DNA damage and apoptosis. Lycopene, a plant-derived antioxidant, synergistically increased QC activity and inhibited Wnt-TCF signaling in cancer cells without affecting the MCF-10A normal breast cell line. Collectively, the data suggest that QC-mediated Wnt-TCF signal inhibition depends on APC and that the addition of lycopene synergistically increases QC anticancer activity.

Scaffold hybridization in generation of indenoindolones as anticancer agents that induce apoptosis with cell cycle arrest at G2/M phase.

Scaffold hybridization of several natural and synthetic anticancer leads led to the consideration of indenoindolones as potential novel anticancer agents. A series of these compounds were prepared by a diversity-feasible synthetic method. They were found to possess anticancer activities with higher potency compared to etoposide and 5-fluorouracil in kidney cancer cells (HEK 293) and low toxicity to corresponding normal cells (Vero). They exerted apoptotic effect with blocking of cell cycle at G2/M phase.

N-fused imidazoles as novel anticancer agents that inhibit catalytic activity of topoisomerase IIα and induce apoptosis in G1/S phase.

On the basis of structures of known topoisomerase II catalytic inhibitors and initial molecular docking studies, bicyclic N-fused aminoimidazoles were predicted as potential topoisomerase II inhibitors. They were synthesized by multicomponent reactions and evaluated against human topoisomerase IIα (hTopoIIα) in decatenation, relaxation, cleavage complex, and DNA intercalation in vitro assays. Among 31 compounds of eight different bicyclic scaffolds, it was found that imidazopyridine, imidazopyrazole, and imidazopyrazine with suitable substituents exhibited potent inhibition of catalytic activity of hTopoIIα while not showing DNA intercalation. Molecular docking studies and molecular dynamics (MD) simulation analysis, ATPase-kinetics and ATP-dependent plasmid relaxation assay revealed the catalytic mode of inhibition of the title compounds plausibly by blocking the ATP-binding site. N-Fused aminoimidazoles showed potent anticancer activities in kidney and breast cancer cell lines, low toxicity to normal cells, relatively higher potency compared to etoposide and 5-fluorouracil in kidney cancer cell lines, and potent inhibition in cell migration. These compounds were found to exert apoptotic effect in G1/S phase.

TRAF2-MLK3 interaction is essential for TNF-alpha-induced MLK3 activation.

Mixed lineage kinase 3 (MLK3) is a mitogen-activated protein kinase kinase kinase that is activated by tumor necrosis factor-alpha (TNF-alpha) and specifically activates c-Jun N-terminal kinase (JNK) on TNF-alpha stimulation. The mechanism by which TNF-alpha activates MLK3 is still not known. TNF receptor-associated factors (TRAFs) are adapter molecules that are recruited to cytoplasmic end of TNF receptor and mediate the downstream signaling, including activation of JNK. Here, we report that MLK3 associates with TRAF2, TRAF5 and TRAF6; however only TRAF2 can significantly induce the kinase activity of MLK3. The interaction domain of TRAF2 maps to the TRAF domain and for MLK3 to its C-terminal half (amino acids 511-847). Endogenous TRAF2 and MLK3 associate with each other in response to TNF-alpha treatment in a time-dependent manner. The association between MLK3 and TRAF2 mediates MLK3 activation and competition with the TRAF2 deletion mutant that binds to MLK3 attenuates MLK3 kinase activity in a dose-dependent manner, on TNF-alpha treatment. Furthermore the downstream target of MLK3, JNK was activated by TNF-alpha in a TRAF2-dependent manner. Hence, our data show that the direct interaction between TRAF2 and MLK3 is required for TNF-alpha-induced activation of MLK3 and its downstream target, JNK.