Synthesis and Quantitative Structure–Activity Relationship of Imidazotetrazine Prodrugs with Activity Independent of O6-Methylguanine-DNA-methyltransferase, DNA Mismatch Repair and p53.

The antitumor prodrug Temozolomide is compromised by its dependence for activity on DNA mismatch repair (MMR) and the repair of the chemosensitive DNA lesion, O6-methylguanine (O6-MeG), by O6-methylguanine-DNA-methyltransferase (EC 2.1.1.63, MGMT). Tumor response is also dependent on wild-type p53. Novel 3-(2-anilinoethyl)-substituted imidazotetrazines are reported that have activity independent of MGMT, MMR and p53. This is achieved through a switch of mechanism so that bioactivity derives from imidazotetrazine-generated arylaziridinium ions that principally modify guanine-N7 sites on DNA. Mono- and bi-functional analogs are reported and a quantitative structure-activity relationship (QSAR) study identified the p-tolyl-substituted bi-functional congener as optimized for potency, MGMT-independence and MMR-independence. NCI60 data show the tumor cell response is distinct from other imidazotetrazines and DNA-guanine-N7 active agents such as nitrogen mustards and cisplatin. The new imidazotetrazine compounds are promising agents for further development and their improved in vitro activity validates the principles on which they were designed

Platinum-(IV)-derivative satraplatin induced G2/M cell cycle perturbation via p53-p21(waf1/cip1)-independent pathway in human colorectal cancer cells

Platinum-(IV)-derivative satraplatin represents a new generation of orally available anti-cancer drugs that are under development for the treatment of several cancers. Understanding the mechanisms of cell cycle modulation and apoptosis is necessary to define the mode of action of satraplatin. In this study, we investigate the ability of satraplatin to induce cell cycle perturbation, clonogenicity loss and apoptosis in colorectal cancer (CRC) cells.Platinum-(IV)-derivative satraplatin represents a new generation of orally available anti-cancer drugs that are under development for the treatment of several cancers. Understanding the mechanisms of cell cycle modulation and apoptosis is necessary to define the mode of action of satraplatin. In this study, we investigate the ability of satraplatin to induce cell cycle perturbation, clonogenicity loss and apoptosis in colorectal cancer (CRC) cells

Human surfactant protein D alters oxidative stress and HMGA1 expression to induce p53 apoptotic pathway in eosinophil leukemic cell line

This article is made available through the Brunel Open Access Publishing Fund. Copyright: © 2013 Mahajan et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Surfactant protein D (SP-D), an innate immune molecule, has an indispensable role in host defense and regulation of inflammation. Immune related functions regulated by SP-D include agglutination of pathogens, phagocytosis, oxidative burst, antigen presentation, T lymphocyte proliferation, cytokine secretion, induction of apoptosis and clearance of apoptotic cells. The present study unravels a novel ability of SP-D to reduce the viability of leukemic cells (eosinophilic leukemic cell line, AML14.3D10; acute myeloid leukemia cell line, THP-1; acute lymphoid leukemia cell lines, Jurkat, Raji; and human breast epithelial cell line, MCF-7), and explains the underlying mechanisms. SP-D and a recombinant fragment of human SP-D (rhSP-D) induced G2/M phase cell cycle arrest, and dose and timedependent apoptosis in the AML14.3D10 eosinophilic leukemia cell line. Levels of various apoptotic markers viz. activated p53, cleaved caspase-9 and PARP, along with G2/M checkpoints (p21 and Tyr15 phosphorylation of cdc2) showed significant increase in these cells. We further attempted to elucidate the underlying mechanisms of rhSP-D induced apoptosis using proteomic analysis. This approach identified large scale molecular changes initiated by SPD in a human cell for the first time. Among others, the proteomics analysis highlighted a decreased expression of survival related proteins such as HMGA1, overexpression of proteins to protect the cells from oxidative burst, while a drastic decrease in mitochondrial antioxidant defense system. rhSP-D mediated enhanced oxidative burst in AML14.3D10 cells was confirmed, while antioxidant, N-acetyl-L-cysteine, abrogated the rhSP-D induced apoptosis. The rhSP-D mediated reduced viability was specific to the cancer cell lines and viability of human PBMCs from healthy controls was not affected. The study suggests involvement of SP-D in host’s immunosurveillance and therapeutic potential of rhSP-D in the eosinophilic leukemia and cancers of other origins.Department of Biotechnology, Indi

The digital mundane, social media and the military

This article draws on empirical data with British military personnel in order to investigate what we call the digital mundane in military life. We argue that social media and smartphone technologies within the military offer a unique environment in which to investigate the ways individual’s position themselves within certain axes of institutional and cultural identities. At the same time, the convolutions, mediatory practices, and mundane social media rituals that service personnel employ through their smartphones resonates widely with, for example, youth culture, digital mobile cultures. Together they suggest complex mediations with social and mobile media, that draws on, and extends non-military practice into new (and increasingly normative) terrains

Kinetic Stabilization of Blue‐Emissive Anthracenes: Phenylene Bridging Works Best

In attempts at kinetically stabilizing blue‐emissive anthracenes, a series of 9,10‐diaryl substituted derivatives were tested for their photochemical and photooxidative persistence. A major breakthrough in light fastness comes from a new bis‐meta‐terphenylyl substituted anthracene which is much superior to industrially relevant 9,10‐biarylated anthracenes. The key issue is the steric shielding of the anthracene core. Further, intramolecular ring closure via Yamamoto coupling furnished a doubly bridged anthracene as a “self‐encapsulated” sky‐blue emitter which is most resistant to photodegradation. The improved stabilization was corroborated by time‐resolved irradiation experiments and rationalized by X‐ray crystallography

The responses of cancer cells to PLK1 inhibitors reveal a novel protective role for p53 in maintaining centrosome separation

Polo-like kinase-1 (PLK1) plays a major role in driving mitotic events, including centrosome disjunction and separation, and is frequently over-expressed in human cancers. PLK1 inhibition is a promising therapeutic strategy and works by arresting cells in mitosis due to monopolar spindles. The p53 tumour suppressor protein is a short-lived transcription factor that can inhibit the growth, or stimulate the death, of developing cancer cells. Curiously, although p53 normally acts in an anti-cancer capacity, it can offer significant protection against inhibitors of PLK1, but the events underpinning this effect are not known. Here, we show that functional p53 reduces the sensitivity to PLK1 inhibitors by permitting centrosome separation to occur, allowing cells to traverse mitosis and re-enter cycle with a normal complement of 2N chromosomes. Protection entails the activation of p53 through the DNA damage-response enzymes, ATM and ATR, and requires the phosphorylation of p53 at the key regulatory site, Ser15. These data highlight a previously unrecognised link between p53, PLK1 and centrosome separation that has therapeutic implications for the use of PLK1 inhibitors in the clinic

Bilateral inhibition of HAUSP deubiquitinase by a viral interferon regulatory factor protein

Herpesvirus-associated ubiquitin specific protease (HAUSP) regulates the stability of p53 and MDM2, implicating HAUSP as a therapeutic target for tuning p53-mediated anti-tumor activity. Here, we report the structural analysis of HAUSP with Kaposi’s sarcoma-associated herpesvirus vIRF4 and the discovery of two vIRF4-derived peptides, vif1 and vif2, as potent and selective HAUSP antagonists. This analysis reveals a bilateral belt-type interaction resulting in inhibition of HAUSP. The vif1 peptide binds the HAUSP TRAF domain, competitively blocking substrate binding, while the vif2 peptide binds both the HAUSP TRAF and catalytic domains, robustly suppressing its deubiquitination activity. Consequently, peptide treatments comprehensively blocked HAUSP, leading to p53-dependent cell cycle arrest and apoptosis in culture and tumor regression in xenograft mouse model. Thus, the virus has developed a unique molecular strategy to target the HAUSP-MDM2-p53 pathway, and these virus-derived short peptides represent biologically active HAUSP antagonists

Three unique coordination geometries involving 1,2-dimethoxy-4,5-bis(2-pyridylethynyl)benzene

Reaction of the new ligand 1,2-dimethoxy-4,5-bis(2-pyridylethynyl) benzene with different metal centers under similar reaction conditions led to three distinct structure formation processes: molecular ring closure, dimerization, and polymer formation

Formation and physicochemical properties of crystalline and amorphous salts with different stoichiometries formed between ciprofloxacin and succinic acid

YesMulti-ionizable compounds, such as dicarboxylic acids, offer the possibility of forming salts of drugs with multiple stoichiometries. Attempts to crystallize ciprofloxacin, a poorly water-soluble, amphoteric molecule with succinic acid (S) resulted in isolation of ciprofloxacin hemisuccinate (1:1) trihydrate (CHS-I) and ciprofloxacin succinate (2:1) tetrahydrate (CS-I). Anhydrous ciprofloxacin hemisuccinate (CHS-II) and anhydrous ciprofloxacin succinate (CS-II) were also obtained. It was also possible to obtain stoichiometrically equivalent amorphous salt forms, CHS-III and CS-III, by spray drying and milling, respectively, of the drug and acid. Anhydrous CHS and CS had melting points at ∼215 and ∼228 °C, while the glass transition temperatures of CHS-III and CS-III were ∼101 and ∼79 °C, respectively. Dynamic solubility studies revealed the metastable nature of CS-I in aqueous media, resulting in a transformation of CS-I to a mix of CHS-I and ciprofloxacin 1:3.7 hydrate, consistent with the phase diagram. CS-III was observed to dissolve noncongruently leading to high and sustainable drug solution concentrations in water at 25 and 37 °C, with the ciprofloxacin concentration of 58.8 ± 1.18 mg/mL after 1 h of the experiment at 37 °C. This work shows that crystalline salts with multiple stoichiometries and amorphous salts have diverse pharmaceutically relevant properties, including molecular, solid state, and solubility characteristics.Solid State Pharmaceutical Cluster (SSPC), supported by Science Foundation Ireland under grant number 07/SRC/ B1158