DNA Repair Modulates The Vulnerability of The Developing Brain to Alkylating Agents

Science.gov (United States)

Kisby, G.E.; Olivas, A.; Park, T.; Churchwell, M.; Doerge, D.; Samson, L. D.; Gerson, S.L.; Turker, M.S.

2009-01-01

Neurons of the developing brain are especially vulnerable to environmental agents that damage DNA (i.e., genotoxicants), but the mechanism is poorly understood. The focus of the present study is to demonstrate that DNA damage plays a key role in disrupting neurodevelopment. To examine this hypothesis, we compared the cytotoxic and DNA damaging properties of the methylating agents methylazoxymethanol (MAM) and dimethyl sulfate (DMS) and the mono- and bifunctional alkylating agents chloroethylamine (CEA) and nitrogen mustard (HN2), in granule cell neurons derived from the cerebellum of neonatal wild type mice and three transgenic DNA repair strains. Wild type cerebellar neurons were significantly more sensitive to the alkylating agents DMS and HN2 than neuronal cultures treated with MAM or the half-mustard CEA. Parallel studies with neuronal cultures from mice deficient in alkylguanine DNA glycosylase (Aag-/-) or O6-methylguanine methyltransferase (Mgmt-/-), revealed significant differences in the sensitivity of neurons to all four genotoxicants. Mgmt-/- neurons were more sensitive to MAM and HN2 than the other genotoxicants and wild type neurons treated with either alkylating agent. In contrast, Aag-/- neurons were for the most part significantly less sensitive than wild type or Mgmt-/- neurons to MAM and HN2. Aag-/- neurons were also significantly less sensitive than wild type neurons treated with either DMS or CEA. Granule cell development and motor function were also more severely disturbed by MAM and HN2 in Mgmt-/- mice than in comparably treated wild type mice. In contrast, cerebellar development and motor function were well preserved in MAM treated Aag-/- or MGMT overexpressing (MgmtTg+) mice, even as compared with wild type mice suggesting that AAG protein increases MAM toxicity, whereas MGMT protein decreases toxicity. Surprisingly, neuronal development and motor function were severely disturbed in MgmtTg+ mice treated with HN2. Collectively, these in vitro

The Scarlet Letter of Alkylation: A Mini Review of Selective Alkylating Agents

Science.gov (United States)

Oronsky, Bryan T; Reid, Tony; Knox, Susan J; Scicinski, Jan J

2012-01-01

If there were a stigma scale for chemotherapy, alkylating agents would be ranked at the top of the list. The chemical term alkylation is associated with nonselective toxicity, an association that dates back to the use of nitrogen mustards during World War I as chemical warfare agents. That this stigma persists and extends to compounds that, through selectivity, attempt to “tame” the indiscriminate destructive potential of alkylation is the subject of this review. Selective alkylation, as it is referred to herein, constitutes an extremely nascent and dynamic field in oncology. The pharmacodynamic response to this selective strategy depends on a delicate kinetic balance between specificity and the rate and extent of binding. Three representative compounds are presented: RRx-001, 3-bromopyruvate, and TH-302. The main impetus for the development of these compounds has been the avoidance of the serious complications of traditional alkylating agents; therefore, it is the thesis of this review that they should not experience stigma by association. PMID:22937173

The scarlet letter of alkylation: a mini review of selective alkylating agents.

Science.gov (United States)

Oronsky, Bryan T; Reid, Tony; Knox, Susan J; Scicinski, Jan J

2012-08-01

If there were a stigma scale for chemotherapy, alkylating agents would be ranked at the top of the list. The chemical term alkylation is associated with nonselective toxicity, an association that dates back to the use of nitrogen mustards during World War I as chemical warfare agents. That this stigma persists and extends to compounds that, through selectivity, attempt to "tame" the indiscriminate destructive potential of alkylation is the subject of this review. Selective alkylation, as it is referred to herein, constitutes an extremely nascent and dynamic field in oncology. The pharmacodynamic response to this selective strategy depends on a delicate kinetic balance between specificity and the rate and extent of binding. Three representative compounds are presented: RRx-001, 3-bromopyruvate, and TH-302. The main impetus for the development of these compounds has been the avoidance of the serious complications of traditional alkylating agents; therefore, it is the thesis of this review that they should not experience stigma by association.

Complex responses to alkylating agents

International Nuclear Information System (INIS)

Samson, L.D.

2003-01-01

Using Affymetrix oligonucleotide GeneChip analysis, we previously found that, upon exposure to the simple alkylating agent methylmethane sulfonate, the transcript levels for about one third of the Saccharomyces cerevisiae genome (∼2,000 transcripts) are induced or repressed during the first hour or two after exposure. In order to determine whether the responsiveness of these genes has any relevance to the protection of cells against alkylating agents we have undertaken several follow-up studies. First, we explored the specificity of this global transcriptional response to MMS by measuring the global response of S. cerevisiae to a broad range of agents that are known to induce DNA damage. We found that each agent produced a very different mRNA transcript profile, even though the exposure doses produced similar levels of toxicity. We also found that the selection of genes that respond to MMS is highly dependent upon what cell cycle phase the cells are in at the time of exposure. Computational clustering analysis of the dataset derived from a large number of exposures identified several promoter motifs that are likely to control some of the regulons that comprise this large set of genes that are responsive to DNA damaging agents. However, it should be noted that these agents damage cellular components other than DNA, and that the responsiveness of each gene need not be in response to DNA damage per se. We have also begun to study the response of other organisms to alkylating agents, and these include E. coli, cultured mouse and human cells, and mice. Finally, we have developed a high throughput phenotypic screening method to interrogate the role of all non-essential S. cerevisiae genes (about 4,800) in protecting S. cerevisiae against the deleterious effects of alkylating agents; we have termed this analysis 'genomic phenotyping'. This study has uncovered a plethora of new pathways that play a role in the recovery of eukaryotic cells after exposure to toxic

Mechanisms of action of quinone-containing alkylating agents: DNA alkylation by aziridinylquinones.

Science.gov (United States)

Hargreaves, R H; Hartley, J A; Butler, J

2000-11-01

Aziridinyl quinones can be activated by cellular reductases eg. DT-diaphorase and cytochrome P450 reductase to form highly reactive DNA alkylating agents. The mechanisms by which this activation and alkylation take place are many and varied. Using clinically relevant and experimental agents this review will describe many of these mechanisms. The agents discussed are Mitomycin C, EO9 and analogues, diaziridinylbenzoquinones and the pyrrolo[1, 2-alpha]benzimidazolequinones.

Detection of Alkylating Agents using Electrical and Mechanical Means

Science.gov (United States)

Gerchikov, Yulia; Borzin, Elena; Gannot, Yair; Shemesh, Ariel; Meltzman, Shai; Hertzog-Ronen, Carmit; Tal, Shay; Stolyarova, Sara; Nemirovsky, Yael; Tessler, Nir; Eichen, Yoav

2011-08-01

Alkylating agents are reactive molecules having at least one polar bond between a carbon atom and a good leaving group. These often simple molecules are frequently used in organic synthesis, as sterilizing agents in agriculture and even as anticancer agents in medicine. Unfortunately, for over a century, some of the highly reactive alkylating agents are also being used as blister chemical warfare agents. Being relatively simple to make, the risk is that these will be applied by terrorists as poor people warfare agents. The detection and identification of such alkylating agents is not a simple task because of their high reactivity and simple structure of the reactive site. Here we report on new approaches to the detection and identification of such alkylating agents using electrical (organic field effect transistors) and mechanical (microcantilevers) means.

Detection of Alkylating Agents using Electrical and Mechanical Means

International Nuclear Information System (INIS)

Gerchikov, Yulia; Borzin, Elena; Gannot, Yair; Shemesh, Ariel; Meltzman, Shai; Hertzog-Ronen, Carmit; Eichen, Yoav; Tal, Shay; Stolyarova, Sara; Nemirovsky, Yael; Tessler, Nir

2011-01-01

Alkylating agents are reactive molecules having at least one polar bond between a carbon atom and a good leaving group. These often simple molecules are frequently used in organic synthesis, as sterilizing agents in agriculture and even as anticancer agents in medicine. Unfortunately, for over a century, some of the highly reactive alkylating agents are also being used as blister chemical warfare agents. Being relatively simple to make, the risk is that these will be applied by terrorists as poor people warfare agents. The detection and identification of such alkylating agents is not a simple task because of their high reactivity and simple structure of the reactive site. Here we report on new approaches to the detection and identification of such alkylating agents using electrical (organic field effect transistors) and mechanical (microcantilevers) means.

Detection of Alkylating Agents using Electrical and Mechanical Means

Energy Technology Data Exchange (ETDEWEB)

Gerchikov, Yulia; Borzin, Elena; Gannot, Yair; Shemesh, Ariel; Meltzman, Shai; Hertzog-Ronen, Carmit; Eichen, Yoav [Schulich Department of Chemistry, Technion-Israel Institute of Technology, Technion City, 32000, Haifa (Israel) (Israel); Tal, Shay [Present address: Systems Biology Department, Harvard Medical School, Boston, MA 02115 (United States); Stolyarova, Sara; Nemirovsky, Yael; Tessler, Nir, E-mail: chryoav@tx.technion.ac.il [Department of Electrical Engineering, Technion-Israel Institute of Technology, Technion City, 32000, Haifa (Israel)

2011-08-17

Alkylating agents are reactive molecules having at least one polar bond between a carbon atom and a good leaving group. These often simple molecules are frequently used in organic synthesis, as sterilizing agents in agriculture and even as anticancer agents in medicine. Unfortunately, for over a century, some of the highly reactive alkylating agents are also being used as blister chemical warfare agents. Being relatively simple to make, the risk is that these will be applied by terrorists as poor people warfare agents. The detection and identification of such alkylating agents is not a simple task because of their high reactivity and simple structure of the reactive site. Here we report on new approaches to the detection and identification of such alkylating agents using electrical (organic field effect transistors) and mechanical (microcantilevers) means.

Mechanisms of resistance to alkylating agents

OpenAIRE

Damia, G.; D‘Incalci, M.

1998-01-01

Alkylating agents are the most widely used anticancer drugs whose main target is the DNA, although how exactly the DNA lesions cause cell death is still not clear. The emergence of resistance to this class of drugs as well as to other antitumor agents is one of the major causes of failure of cancer treatment. This paper reviews some of the best characterized mechanisms of resistance to alkylating agents. Pre- and post-target mechanisms are recognized, the former able to limit the formation of...

Bifunctional chelating agent for the design and development of site specific radiopharmaceuticals and biomolecule conjugation strategy

Science.gov (United States)

Katti, Kattesh V.; Prabhu, Kandikere R.; Gali, Hariprasad; Pillarsetty, Nagavara Kishore; Volkert, Wynn A.

2003-10-21

There is provided a method of labeling a biomolecule with a transition metal or radiometal in a site specific manner to produce a diagnostic or therapeutic pharmaceutical compound by synthesizing a P.sub.2 N.sub.2 -bifunctional chelating agent intermediate, complexing the intermediate with a radio metal or a transition metal, and covalently linking the resulting metal-complexed bifunctional chelating agent with a biomolecule in a site specific manner. Also provided is a method of synthesizing the --PR.sub.2 containing biomolecules by synthesizing a P.sub.2 N.sub.2 -bifunctional chelating agent intermediate, complexing the intermediate with a radiometal or a transition metal, and covalently linking the resulting radio metal-complexed bifunctional chelating agent with a biomolecule in a site specific manner. There is provided a therapeutic or diagnostic agent comprising a --PR.sub.2 containing biomolecule.

Molecular design of sequence specific DNA alkylating agents.

Science.gov (United States)

Minoshima, Masafumi; Bando, Toshikazu; Shinohara, Ken-ichi; Sugiyama, Hiroshi

2009-01-01

Sequence-specific DNA alkylating agents have great interest for novel approach to cancer chemotherapy. We designed the conjugates between pyrrole (Py)-imidazole (Im) polyamides and DNA alkylating chlorambucil moiety possessing at different positions. The sequence-specific DNA alkylation by conjugates was investigated by using high-resolution denaturing polyacrylamide gel electrophoresis (PAGE). The results showed that polyamide chlorambucil conjugates alkylate DNA at flanking adenines in recognition sequences of Py-Im polyamides, however, the reactivities and alkylation sites were influenced by the positions of conjugation. In addition, we synthesized conjugate between Py-Im polyamide and another alkylating agent, 1-(chloromethyl)-5-hydroxy-1,2-dihydro-3H-benz[e]indole (seco-CBI). DNA alkylation reactivies by both alkylating polyamides were almost comparable. In contrast, cytotoxicities against cell lines differed greatly. These comparative studies would promote development of appropriate sequence-specific DNA alkylating polyamides against specific cancer cells.

Enantioselective Alkylation of 2-Oxindoles Catalyzed by a Bifunctional Phase-Transfer Catalyst: Synthesis of (-)-Debromoflustramine B.

Science.gov (United States)

Craig, Ryan; Sorrentino, Emiliano; Connon, Stephen J

2018-03-26

A new bifunctional phase-transfer catalyst that employs hydrogen bonding as a control element was developed to promote efficient enantioselective S N 2 reactions for the construction all-carbon quaternary stereocenters in high yield and excellent enantioselectivity (up to 97 % ee) utilizing the alkylation of a malleable oxindole substrate. The utility of the methodology was demonstrated through a concise and highly enantioselective synthesis of (-)-debromoflustramine B. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mechanisms of chemoresistance to alkylating agents in malignant glioma.

Science.gov (United States)

Sarkaria, Jann N; Kitange, Gaspar J; James, C David; Plummer, Ruth; Calvert, Hilary; Weller, Michael; Wick, Wolfgang

2008-05-15

Intrinsic or acquired chemoresistance to alkylating agents is a major cause of treatment failure in patients with malignant brain tumors. Alkylating agents, the mainstay of treatment for brain tumors, damage the DNA and induce apoptosis, but the cytotoxic activity of these agents is dependent on DNA repair pathways. For example, O6-methylguanine DNA adducts can cause double-strand breaks, but this is dependent on a functional mismatch repair pathway. Thus, tumor cell lines deficient in mismatch repair are resistant to alkylating agents. Perhaps the most important mechanism of resistance to alkylating agents is the DNA repair enzyme O6-methylguanine methyltransferase, which can eliminate the cytotoxic O6-methylguanine DNA adduct before it causes harm. Another mechanism of resistance to alkylating agents is the base excision repair (BER) pathway. Consequently, efforts are ongoing to develop effective inhibitors of BER. Poly(ADP-ribose)polymerase plays a pivotal role in BER and is an important therapeutic target. Developing effective strategies to overcome chemoresistance requires the identification of reliable preclinical models that recapitulate human disease and which can be used to facilitate drug development. This article describes the diverse mechanisms of chemoresistance operating in malignant glioma and efforts to develop reliable preclinical models and novel pharmacologic approaches to overcome resistance to alkylating agents.

Aryl sulfonate based anticancer alkylating agents.

Science.gov (United States)

Sheikh, Hamdullah Khadim; Arshad, Tanzila; Kanwal, Ghazala

2018-05-01

This research work revolves around synthesis of antineoplastic alkylating sulfonate esters with dual alkylating sites for crosslinking of the DNA strands. These molecules were evaluated as potential antineoplastic cross linking alkylating agents by reaction with the nucleoside of Guanine DNA nucleobase at both ends of the synthesized molecule. Synthesis of the alkylating molecules and the crosslinking with the guanosine nucleoside was monitored by MALDITOF mass spectroscopy. The synthesized molecule's crosslinking or adduct forming rate with the nucleoside was compared with that of 1,4 butane disulfonate (busulfan), in form of time taken for the appearance of [M+H] + . It was found that aryl sulfonate leaving group was causing higher rate of nucleophilic attack by the Lewis basic site of the nucleobase. Furthermore, the rate was also found to be a function of electron withdrawing or donating nature of the substituent on the aryl ring. Compound with strong electron withdrawing substituent on the para position of the ring reacted fastest. Hence, new alkylating agents were synthesized with optimized or desired reactivity.

Perspectives in the development of hybrid bifunctional antitumour agents.

Science.gov (United States)

Musso, Loana; Dallavalle, Sabrina; Zunino, Franco

2015-08-15

In spite of the development of a large number of novel target-specific antitumour agents, the single-agent therapy is in general not able to provide an effective durable control of the malignant process. The limited efficacy of the available agents (both conventional cytotoxic and novel target-specific) reflects not only the expression of defence mechanisms, but also the complexity of tumour cell alterations and the redundancy of survival pathways, thus resulting in tumour cell ability to survive under stress conditions. A well-established strategy to improve the efficacy of antitumour therapy is the rational design of drug combinations aimed at achieving synergistic effects and overcoming drug resistance. An alternative strategy could be the use of agents designed to inhibit simultaneously multiple cellular targets relevant to tumour growth/survival. Among these novel agents are hybrid bifunctional drugs, i.e. compounds resulting by conjugation of different drugs or containing the pharmocophores of different drugs. This strategy has been pursued using various conventional or target-specific agents (with DNA damaging agents and histone deacetylase inhibitors as the most exploited compounds). A critical overview of the most representative compounds is provided with emphasis on the HDAC inhibitor-based hybrid agents. In spite of some promising results, the actual pharmacological advantages of the hybrid agents remain to be defined. This commentary summarizes the recent advances in this field and highlights the pharmacological basis for a rational design of hybrid bifunctional agents. Copyright © 2015. Published by Elsevier Inc.

Synergy of irofulven in combination with other DNA damaging agents: synergistic interaction with altretamine, alkylating, and platinum-derived agents in the MV522 lung tumor model.

Science.gov (United States)

Kelner, Michael J; McMorris, Trevor C; Rojas, Rafael J; Estes, Leita A; Suthipinijtham, Pharnuk

2008-12-01

Irofulven (MGI 114, NSC 683863) is a semisynthetic derivative of illudin S, a natural product present in the Omphalotus illudins (Jack O'Lantern) mushroom. This novel agent produces DNA damage, that in contrast to other agents, is predominately ignored by the global genome repair pathway of the nucleotide excision repair (NER)(2) system. The aim of this study was to determine the antitumor activity of irofulven when administered in combination with 44 different DNA damaging agents, whose damage is in general detected and repaired by the genome repair pathway. The human lung carcinoma MV522 cell line and its corresponding xenograft model were used to evaluate the activity of irofulven in combination with different DNA damaging agents. Two main classes of DNA damaging agents, platinum-derived agents, and select bifunctional alkylating agents, demonstrated in vivo synergistic or super-additive interaction with irofulven. DNA helicase inhibiting agents also demonstrated synergy in vitro, but an enhanced interaction with irofulven could not be demonstrated in vivo. There was no detectable synergistic activity between irofulven and agents capable of inducing DNA cleavage or intercalating into DNA. These results indicate that the antitumor activity of irofulven is enhanced when combined with platinum-derived agents, altretamine, and select alkylating agents such as melphalan or chlorambucil. A common factor between these agents appears to be the production of intrastrand DNA crosslinks. The synergistic interaction between irofulven and other agents may stem from the nucleotide excision repair system being selectively overwhelmed at two distinct points in the pathway, resulting in prolonged stalling of transcription forks, and subsequent initiation of apoptosis.

Development of novel alkylating drugs as anticancer agents.

Science.gov (United States)

Izbicka, Elzbieta; Tolcher, Anthony W

2004-06-01

Although conventional alkylating drugs have proven efficacy in the treatment of malignancies, the agents themselves are not selective. Therefore, non-specific alkylation of cellular nucleophilic targets may contribute to many of the observed toxic effects. Novel approaches to drug discovery have resulted in candidate agents that are focused on 'soft alkylation'--alkylators with greater target selectivity. This review highlights the discovery of small molecule drugs that bind to DNA with higher selectivity, act in a unique hypoxic tumor environment, or covalently bind specific protein targets overexpressed in cancer, such as topoisomerase II, glutathione transferase pi1, beta-tubulin and histone deacetylase.

Balancing repair and tolerance of DNA damage caused by alkylating agents.

Science.gov (United States)

Fu, Dragony; Calvo, Jennifer A; Samson, Leona D

2012-01-12

Alkylating agents constitute a major class of frontline chemotherapeutic drugs that inflict cytotoxic DNA damage as their main mode of action, in addition to collateral mutagenic damage. Numerous cellular pathways, including direct DNA damage reversal, base excision repair (BER) and mismatch repair (MMR), respond to alkylation damage to defend against alkylation-induced cell death or mutation. However, maintaining a proper balance of activity both within and between these pathways is crucial for a favourable response of an organism to alkylating agents. Furthermore, the response of an individual to alkylating agents can vary considerably from tissue to tissue and from person to person, pointing to genetic and epigenetic mechanisms that modulate alkylating agent toxicity.

Bifunctional Rhodium Intercalator Conjugates as Mismatch-Directing DNA Alkylating Agents

OpenAIRE

Schatzschneider, Ulrich; Barton, Jacqueline K.

2004-01-01

A conjugate of a DNA mismatch-specific rhodium intercalator, containing the bulky chrysenediimine ligand, and an aniline mustard has been prepared, and targeting of mismatches in DNA by this conjugate has been examined. The preferential alkylation of mismatched over fully matched DNA is found by a mobility shift assay at concentrations where untethered organic mustards show little reaction. The binding site of the Rh intercalator was determined by DNA photocleavage, and the position of covale...

Embryotoxicity induced by alkylating agents. Some methodological aspects of DNA alkylation studies in murine embryos using ethylmethanesulfonate.

Science.gov (United States)

Platzek, T; Bochert, G; Rahm, U; Neubert, D

1987-05-01

Synthesis and spectroscopic analysis of some alkylated DNA purine bases are described. HPLC separation methods are developed for the determination of DNA alkylation rates in mammalian embryonic tissues. Following treatment of pregnant mice with the ethylating agent ethylmethanesulfonate (EMS), an appreciable amount of alkylation (ethylation and methylation) was found in the nuclear DNA of the embryos during organogenesis. The results are discussed in context of our thesis that a certain amount of DNA alkylation in the embryos is correlated to the teratogenic potential of alkylating agents.

Why Does Alkylation of the N–H Functionality within M/NH Bifunctional Noyori-Type Catalysts Lead to Turnover?

International Nuclear Information System (INIS)

Dub, Pavel; Gordon, John Cameron; Scott, Brian Lindley

2017-01-01

Molecular metal/NH bifunctional Noyori-type catalysts are remarkable in that they are among the most efficient artificial catalysts developed to date for the hydrogenation of carbonyl functionalities (loadings up to ~10 –5 mol %). In addition, these catalysts typically exhibit high C=O/C=C chemo- and enantioselectivities. This unique set of properties is traditionally associated with the operation of an unconventional mechanism for homogeneous catalysts in which the chelating ligand plays a key role in facilitating the catalytic reaction and enabling the aforementioned selectivities by delivering/accepting a proton (H + ) via its N–H bond cleavage/formation. A recently revised mechanism of the Noyori hydrogenation reaction (Dub, P. A. et al. J. Am. Chem. Soc. 2014, 136, 3505) suggests that the N–H bond is not cleaved but serves to stabilize the turnover-determining transition states (TDTSs) via strong N–H···O hydrogen-bonding interactions (HBIs). Here, the present paper shows that this is consistent with the largely ignored experimental fact that alkylation of the N–H functionality within M/NH bifunctional Noyori-type catalysts leads to detrimental catalytic activity. Finally, the purpose of this work is to demonstrate that decreasing the strength of this HBI, ultimately to the limit of its complete absence, are conditions under which the same alkylation may lead to beneficial catalytic activity.

Possible targets for the aneugenic activity of alkylating agents

Energy Technology Data Exchange (ETDEWEB)

Pellerano, P. [IST-National Institute for Research on Cancer, Genova (Italy); Abbondandolo, A. [Univ. of Genova (Italy); Bonatti, S.; Simili, M. [CNR Institute of Mutagenesis and Differentiation, Pisa (Italy)

1993-12-31

Alkylating agents have been of invaluable help in mutation research for half a century. In all tested organisms, they have proved able to induce a large variety of genetic effects, including aneuploidy. Credible molecular models exist to explain the ability of alkylating agents to induce gene mutation and to act as initiators in carcinogenesis as a consequence of DNA alkylation at specific sites. On the contrary, neither the mechanism of aneuploidy induction nor the relevant cellular targets are known.

Sorbate-nitrite interactions: acetonitrile oxide as an alkylating agent.

Science.gov (United States)

Pérez-Prior, M Teresa; Gómez-Bombarelli, Rafael; González-Pérez, Marina; Manso, José A; García-Santos, M Pilar; Calle, Emilio; Casado, Julio

2009-07-01

Because chemical species with DNA-damaging and mutagenic activity are formed in sorbate-nitrite mixtures and because sorbic acid sometimes coexists with nitrite occurring naturally or incorporated as a food additive, the study of sorbate-nitrite interactions is important. Here, the alkylating potential of the products resulting from such interactions was investigated. Drawn were the following conclusions: (i) Acetonitrile oxide (ACNO) is the compound responsible for the alkylating capacity of sorbate-nitrite mixtures; (ii) ACNO alkylates 4-(p-nitrobenzyl)pyridine (NBP), a trap for alkylating agents with nucleophilic characteristics similar to those of DNA bases, forming an adduct (AD; epsilon = 1.4 x 10(4) M(-1) cm(-1); lambda = 519 nm); (iii) the NBP alkylation reaction complies with the rate equation, r = d[AD]/dt = k(alk)(ACNO)[ACNO][NBP]-k(hyd)(AD)[AD], k(alk)(ACNO) being the NBP alkylation rate constant for ACNO and k(hyd)(AD) the rate constant for the adduct hydrolysis reaction; (iv) the small fraction of ACNO forming the adduct with NBP, as well as the small magnitude of the quotient (k(alk) (ACNO)/k(hyd)(ACNO)) as compared with those reported for other alkylating agents, such as some lactones and N-alkyl-N-nitrosoureas, reveals the ACNO effective alkylating capacity to be less significant; (v) the low value of the NBP-ACNO adduct life (defined as the total amount of adduct present along the progression of the NBP alkylation per unit of alkylating agent concentration) points to the high instability of this adduct; and (vi) the obtained results are in accordance with the low carcinogenicity of ACNO.

Distribution of methyl and ethyl adducts following alkylation with monofunctional alkylating agents.

Science.gov (United States)

Beranek, D T

1990-07-01

Alkylating agents, because of their ability to react directly with DNA either in vitro or in vivo, or following metabolic activation as in the case of the dialkylnitrosamines, have been used extensively in studying the mechanisms of mutagenicity and carcinogenicity. Their occurrence is widespread in the environment and human exposure from natural and pollutant sources is universal. Since most of these chemicals show varying degrees of both carcinogenicity and mutagenicity, and exhibit compound-specific binding patterns, they provide an excellent model for studying molecular dosimetry. Molecular dosimetry defines dose as the number of adducts bound per macromolecule and relates the binding of these adducts to the human mutagenic or carcinogenic response. This review complies DNA alkylation data for both methylating and ethylating agents in a variety of systems and discusses the role these alkylation products plays in molecular mutagenesis.

Detection and identification of alkylating agents by using a bioinspired "chemical nose".

Science.gov (United States)

Hertzog-Ronen, Carmit; Borzin, Elena; Gerchikov, Yulia; Tessler, Nir; Eichen, Yoav

2009-10-12

Alkylating agents are simple and reactive molecules that are commonly used in many and diverse fields such as organic synthesis, medicine, and agriculture. Some highly reactive alkylating species are also being used as blister chemical-warfare agents. The detection and identification of alkylating agents is not a trivial issue because of their high reactivity and simple structure. Herein, we report on a new multispot luminescence-based approach to the detection and identification of alkylating agents. In order to demonstrate the potential of the approach, seven pi-conjugated oligomers and polymers bearing nucleophilic pyridine groups, 1-7, were adsorbed onto a solid support and exposed to vapors of alkylators 8-15. The alkylation-induced color-shift patterns of the seven-spot array allow clear discrimination of the different alkylators. The spots are sensitive to minute concentrations of alkylators and, because the detection is based on the formation of new covalent bonds, these spots saturate at about 50 ppb.

Determination of reaction rate constants for alkylation of 4-(p-nitrobenzyl) pyridine by different alkylating agents.

Science.gov (United States)

Walles, S A

1980-02-01

The rate constants have been determined for the reaction between some different alkylating agents and 4-(p-nitrobenzyl) pyridine (NBP) in methanol. These constants have been compared with those for alkylation of aniline in water. All the constants were lower in methanol than in water but in different degrees. The rate constants of the different alkylating agents have been calculated at a nucleophilic strength n=2. The genetic risk defined as the degree of alkylation of a nucleophile (n=2) is equivalent to the rate constant kn=2 and the target dose. The dependence of the genetic risk on the rate constant (kn=2) is discussed.

From old alkylating agents to new minor groove binders.

Science.gov (United States)

Puyo, Stéphane; Montaudon, Danièle; Pourquier, Philippe

2014-01-01

Alkylating agents represent the oldest class of anticancer agents with the approval of mechloretamine by the FDA in 1949. Even though their clinical use is far beyond the use of new targeted therapies, they still occupy a major place in the treatment of specific malignancies, sometimes representing the unique option for the treatment of refractory tumors. Here, we are reviewing the major classes of alkylating agents, with a particular focus on the latest generations of compounds that specifically target the minor groove of the DNA. These naturally occurring derivatives have a unique mechanism of action that explains the recent regain of interest in developing new classes of alkylating agents that could be used in combination with other anticancer drugs to enhance tumor response in the clinic. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

[Bifunctional chelates of Rh-105, Au-199, and other metallic radionuclides as potential radiotherapeutic agents

International Nuclear Information System (INIS)

1991-01-01

Progress during this period is reported under the following headings: Diethylenetriamine based and related bifunctional chelating agents and their complexation with Rh-105, Au-198, Pd-109, cu-67, In-111, and Co-57; studies of Pd-109, Rh-105 and Tc-99m with bifunctional chelates based on phenylenediamine; establishment of an appropriate protein assay method for conjugated proteins; studies of new bifunctional Bi, Tri and tetradentate amine oxime ligands with Rh-105; IgG and antibody B72.3 conjugation studies by HPLC Techniques with bifunctional metal chelates; and progress on ligand systems for Au(III)

[Bifunctional chelates of Rh-105, Au-199, and other metallic radionuclides as potential radiotherapeutic agents

Energy Technology Data Exchange (ETDEWEB)

1991-12-31

Progress during this period is reported under the following headings: Diethylenetriamine based and related bifunctional chelating agents and their complexation with Rh-105, Au-198, Pd-109, cu-67, In-111, and Co-57; studies of Pd-109, Rh-105 and Tc-99m with bifunctional chelates based on phenylenediamine; establishment of an appropriate protein assay method for conjugated proteins; studies of new bifunctional Bi, Tri and tetradentate amine oxime ligands with Rh-105; IgG and antibody B72.3 conjugation studies by HPLC Techniques with bifunctional metal chelates; and progress on ligand systems for Au(III).

(Bifunctional chelates of Rh-105, Au-199, and other metallic radionuclides as potential radiotherapeutic agents)

Energy Technology Data Exchange (ETDEWEB)

1991-01-01

Progress during this period is reported under the following headings: Diethylenetriamine based and related bifunctional chelating agents and their complexation with Rh-105, Au-198, Pd-109, cu-67, In-111, and Co-57; studies of Pd-109, Rh-105 and Tc-99m with bifunctional chelates based on phenylenediamine; establishment of an appropriate protein assay method for conjugated proteins; studies of new bifunctional Bi, Tri and tetradentate amine oxime ligands with Rh-105; IgG and antibody B72.3 conjugation studies by HPLC Techniques with bifunctional metal chelates; and progress on ligand systems for Au(III).

Quantitative estimation of the extent of alkylation of DNA following treatment of mammalian cells with non-radioactive alkylating agents

Energy Technology Data Exchange (ETDEWEB)

Snyder, R.D. (Univ. of Tennessee, Oak Ridge); Regan, J.D.

1981-01-01

Alkaline sucrose sedimentation has been used to quantitate phosphotriester formation following treatment of human cells with the monofunctional alkylating agents methyl and ethyl methanesulfonate. These persistent alkaline-labile lesions are not repaired during short-term culture conditions and thus serve as a useful and precise index of the total alkylation of the DNA.Estimates of alkylation by this procedure compare favorably with direct estimates by use of labeled alkylating agents.

DNA minor groove alkylating agents.

Science.gov (United States)

Denny, W A

2001-04-01

Recent work on a number of different classes of anticancer agents that alkylate DNA in the minor groove is reviewed. There has been much work with nitrogen mustards, where attachment of the mustard unit to carrier molecules can change the normal patterns of both regio- and sequence-selectivity, from reaction primarily at most guanine N7 sites in the major groove to a few adenine N3 sites at the 3'-end of poly(A/T) sequences in the minor groove. Carrier molecules discussed for mustards are intercalators, polypyrroles, polyimidazoles, bis(benzimidazoles), polybenzamides and anilinoquinolinium salts. In contrast, similar targeting of pyrrolizidine alkylators by a variety of carriers has little effect of their patterns of alkylation (at the 2-amino group of guanine). Recent work on the pyrrolobenzodiazepine and cyclopropaindolone classes of natural product minor groove binders is also reviewed.

Chemotherapy-induced pulmonary hypertension: role of alkylating agents.

Science.gov (United States)

Ranchoux, Benoît; Günther, Sven; Quarck, Rozenn; Chaumais, Marie-Camille; Dorfmüller, Peter; Antigny, Fabrice; Dumas, Sébastien J; Raymond, Nicolas; Lau, Edmund; Savale, Laurent; Jaïs, Xavier; Sitbon, Olivier; Simonneau, Gérald; Stenmark, Kurt; Cohen-Kaminsky, Sylvia; Humbert, Marc; Montani, David; Perros, Frédéric

2015-02-01

Pulmonary veno-occlusive disease (PVOD) is an uncommon form of pulmonary hypertension (PH) characterized by progressive obstruction of small pulmonary veins and a dismal prognosis. Limited case series have reported a possible association between different chemotherapeutic agents and PVOD. We evaluated the relationship between chemotherapeutic agents and PVOD. Cases of chemotherapy-induced PVOD from the French PH network and literature were reviewed. Consequences of chemotherapy exposure on the pulmonary vasculature and hemodynamics were investigated in three different animal models (mouse, rat, and rabbit). Thirty-seven cases of chemotherapy-associated PVOD were identified in the French PH network and systematic literature analysis. Exposure to alkylating agents was observed in 83.8% of cases, mostly represented by cyclophosphamide (43.2%). In three different animal models, cyclophosphamide was able to induce PH on the basis of hemodynamic, morphological, and biological parameters. In these models, histopathological assessment confirmed significant pulmonary venous involvement highly suggestive of PVOD. Together, clinical data and animal models demonstrated a plausible cause-effect relationship between alkylating agents and PVOD. Clinicians should be aware of this uncommon, but severe, pulmonary vascular complication of alkylating agents. Copyright © 2015 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

Photogeneration and reactivity of naphthoquinone methides as purine selective DNA alkylating agents.

Science.gov (United States)

Verga, Daniela; Nadai, Matteo; Doria, Filippo; Percivalle, Claudia; Di Antonio, Marco; Palumbo, Manlio; Richter, Sara N; Freccero, Mauro

2010-10-20

A one-step protecting-group-free synthesis of both 6-hydroxy-naphthalene-2-carbaldehyde and the bifunctional binaphthalenyl derivative afforded 6-hydroxymethylnaphthalen-2-ol, 6-methylaminomethyl-naphthalen-2-ol, [(2-hydroxy-3-naphthyl)methyl]trimethyl ammonium iodide, and a small library of bifunctional binol analogues in good yields. Irradiation of naphthol quaternary ammonium salt and binol-derivatives (X = OH, NHR, NMe(3)(+), OCOCH(3), and L-proline) at 310 and 360 nm resulted in the photogeneration of the 2,6-naphthoquinone-6-methide (NQM) and binol quinone methide analogues (BQMs) by a water-mediated excited-state proton transfer (ESPT). The hydration, the mono- and bis-alkylation reactions of morpholine and 2-ethanethiol, as N and S prototype nucleophiles, by the transient NQM (λ(max) 310, 330 nm) and BQMs (λ(max) 360 nm) were investigated in water by product distribution analysis and laser flash photolysis (LFP). Both the photogeneration and the reactivity of NQM and BQMs exhibited striking differences. BQMs were at least 2 orders of magnitude more reactive than NQM, and they were generated much more efficiently from a greater variety of photoprecursors including the hydroxymethyl, quaternary ammonium salt and several binol-amino acids. On the contrary, the only efficient precursor of NQM was the quaternary ammonium salt. All water-soluble BQM precursors were further investigated for their ability to alkylate and cross-link plasmid DNA and oligonucleotides by gel electrophoresis: the BQMs were more efficient than the isomeric o-BQM (binol quinone methide analogue of 2,3-naphthoquinone-3-methide). Sequence analysis by gel electrophoresis, HPLC, and MS showed that the alkylation occurred at purines, with a preference for guanine. In particular, a BQM was able to alkylate N7 of guanines resulting in depurination at the oligonucleotide level, and ribose loss at the nucleotide level. The photoreactivity of BQM precursors translated into photocytotoxic and

Bis(trialkylsilyl) peroxides as alkylating agents in the copper-catalyzed selective mono-N-alkylation of primary amides.

Science.gov (United States)

Sakamoto, Ryu; Sakurai, Shunya; Maruoka, Keiji

2017-06-13

The copper-catalyzed selective mono-N-alkylation of primary amides with bis(trialkylsilyl) peroxides as alkylating agents was reported. The results of a mechanistic study suggest that this reaction should proceed via a free radical process that includes the generation of alkyl radicals from bis(trialkylsilyl) peroxides.

Leukemia after therapy with alkylating agents for childhood cancer

International Nuclear Information System (INIS)

Tucker, M.A.; Meadows, A.T.; Boice, J.D. Jr.

1987-01-01

The risk of leukemia was evaluated in 9,170 2-or-more-year survivors of childhood cancer in the 13 institutions of the Late Effects Study Group. Secondary leukemia occurred in 22 nonreferred individuals compared to 1.52 expected, based on general population rates [relative risk (RR) = 14; 95% confidence interval (CI), 9-22]. The influence of therapy for the first cancer on subsequent leukemia risk was determined by a case-control study conducted on 25 cases and 90 matched controls. Treatment with alkylating agents was associated with a significantly elevated risk of leukemia (RR = 4.8; 95% CI, 1.2-18.9). A strong dose-response relationship was also observed between leukemia risk and total dose of alkylating agents, estimated by an alkylator score. The RR of leukemia reached 23 in the highest dose category. Radiation therapy, however, did not increase risk. Although doxorubicin was also identified as a possible risk factor, the excess risk of leukemia following treatment for childhood cancer appears almost entirely due to alkylating agents

Amino acid nitrosation products as alkylating agents.

Science.gov (United States)

García-Santos, M del P; Calle, E; Casado, J

2001-08-08

Nitrosation reactions of alpha-, beta-, and gamma-amino acids whose reaction products can act as alkylating agents of DNA were investigated. To approach in vivo conditions for the two-step mechanism (nitrosation and alkylation), nitrosation reactions were carried out in aqueous acid conditions (mimicking the conditions of the stomach lumen) while the alkylating potential of the nitrosation products was investigated at neutral pH, as in the stomach lining cells into which such products can diffuse. These conclusions were drawn: (i) The alkylating species resulting from the nitrosation of amino acids with an -NH(2) group are the corresponding lactones; (ii) the sequence of alkylating power is: alpha-lactones > beta-lactones > gamma-lactones, coming respectively from the nitrosation of alpha-, beta-, and gamma-amino acids; and (iii) the results obtained may be useful in predicting the mutagenic effectiveness of the nitrosation products of amino acids.

Synthesis and Performance of a Biomimetic Indicator for Alkylating Agents.

Science.gov (United States)

Provencher, Philip A; Love, Jennifer A

2015-10-02

4-(4-Nitrobenzyl)pyridine (NBP) is a colorimetric indicator compound for many types of carcinogenic alkylating agents. Because of the similar reactivity of NBP and guanine in DNA, NBP serves as a DNA model. NBP assays are used in the toxicological screening of pharmaceutical compounds, detection of chemical warfare agents, environmental hygiene technology, preliminary toxicology tests, mutagenicity of medicinal compounds, and other chemical analyses. Nevertheless, the use of NBP as a DNA model suffers from the compound's low water solubility, its lack of reactive oxygen sites, and dissimilar steric encumbrance compared to DNA. We report herein the design and synthesis of NBP derivatives that address some of these issues. These derivatives have been tested in solution and found to be superior in the colorimetric assay of the alkylating anticancer drug cyclophosphamide. The derivatives have also been integrated into a polymeric silica material which changes color upon the exposure to dangerous alkylating agents, such as iodomethane vapor, without the need for an exogenous base. This material modernizes the NBP assay from a time-consuming laboratory analysis to a real-time solid state sensor, which requires neither solvent nor additional reagents and can detect both gas- and solution-phase alkylating agents.

Alcohols as alkylating agents in heteroarene C-H functionalization

Science.gov (United States)

Jin, Jian; MacMillan, David W. C.

2015-09-01

Redox processes and radical intermediates are found in many biochemical processes, including deoxyribonucleotide synthesis and oxidative DNA damage. One of the core principles underlying DNA biosynthesis is the radical-mediated elimination of H2O to deoxygenate ribonucleotides, an example of `spin-centre shift', during which an alcohol C-O bond is cleaved, resulting in a carbon-centred radical intermediate. Although spin-centre shift is a well-understood biochemical process, it is underused by the synthetic organic chemistry community. We wondered whether it would be possible to take advantage of this naturally occurring process to accomplish mild, non-traditional alkylation reactions using alcohols as radical precursors. Because conventional radical-based alkylation methods require the use of stoichiometric oxidants, increased temperatures or peroxides, a mild protocol using simple and abundant alkylating agents would have considerable use in the synthesis of diversely functionalized pharmacophores. Here we describe the development of a dual catalytic alkylation of heteroarenes, using alcohols as mild alkylating reagents. This method represents the first, to our knowledge, broadly applicable use of unactivated alcohols as latent alkylating reagents, achieved via the successful merger of photoredox and hydrogen atom transfer catalysis. The value of this multi-catalytic protocol has been demonstrated through the late-stage functionalization of the medicinal agents, fasudil and milrinone.

Alcohols as alkylating agents in heteroarene C-H functionalization.

Science.gov (United States)

Jin, Jian; MacMillan, David W C

2015-09-03

Redox processes and radical intermediates are found in many biochemical processes, including deoxyribonucleotide synthesis and oxidative DNA damage. One of the core principles underlying DNA biosynthesis is the radical-mediated elimination of H2O to deoxygenate ribonucleotides, an example of 'spin-centre shift', during which an alcohol C-O bond is cleaved, resulting in a carbon-centred radical intermediate. Although spin-centre shift is a well-understood biochemical process, it is underused by the synthetic organic chemistry community. We wondered whether it would be possible to take advantage of this naturally occurring process to accomplish mild, non-traditional alkylation reactions using alcohols as radical precursors. Because conventional radical-based alkylation methods require the use of stoichiometric oxidants, increased temperatures or peroxides, a mild protocol using simple and abundant alkylating agents would have considerable use in the synthesis of diversely functionalized pharmacophores. Here we describe the development of a dual catalytic alkylation of heteroarenes, using alcohols as mild alkylating reagents. This method represents the first, to our knowledge, broadly applicable use of unactivated alcohols as latent alkylating reagents, achieved via the successful merger of photoredox and hydrogen atom transfer catalysis. The value of this multi-catalytic protocol has been demonstrated through the late-stage functionalization of the medicinal agents, fasudil and milrinone.

ATM regulates 3-methylpurine-DNA glycosylase and promotes therapeutic resistance to alkylating agents.

Science.gov (United States)

Agnihotri, Sameer; Burrell, Kelly; Buczkowicz, Pawel; Remke, Marc; Golbourn, Brian; Chornenkyy, Yevgen; Gajadhar, Aaron; Fernandez, Nestor A; Clarke, Ian D; Barszczyk, Mark S; Pajovic, Sanja; Ternamian, Christian; Head, Renee; Sabha, Nesrin; Sobol, Robert W; Taylor, Michael D; Rutka, James T; Jones, Chris; Dirks, Peter B; Zadeh, Gelareh; Hawkins, Cynthia

2014-10-01

Alkylating agents are a first-line therapy for the treatment of several aggressive cancers, including pediatric glioblastoma, a lethal tumor in children. Unfortunately, many tumors are resistant to this therapy. We sought to identify ways of sensitizing tumor cells to alkylating agents while leaving normal cells unharmed, increasing therapeutic response while minimizing toxicity. Using an siRNA screen targeting over 240 DNA damage response genes, we identified novel sensitizers to alkylating agents. In particular, the base excision repair (BER) pathway, including 3-methylpurine-DNA glycosylase (MPG), as well as ataxia telangiectasia mutated (ATM), were identified in our screen. Interestingly, we identified MPG as a direct novel substrate of ATM. ATM-mediated phosphorylation of MPG was required for enhanced MPG function. Importantly, combined inhibition or loss of MPG and ATM resulted in increased alkylating agent-induced cytotoxicity in vitro and prolonged survival in vivo. The discovery of the ATM-MPG axis will lead to improved treatment of alkylating agent-resistant tumors. Inhibition of ATM and MPG-mediated BER cooperate to sensitize tumor cells to alkylating agents, impairing tumor growth in vitro and in vivo with no toxicity to normal cells, providing an ideal therapeutic window. ©2014 American Association for Cancer Research.

Alcohols as alkylating agents in heteroarene C–H functionalization

Science.gov (United States)

Jin, Jian; MacMillan, David W. C.

2015-01-01

Redox processes and radical intermediates are found in many biochemical processes, including deoxyribonucleotide synthesis and oxidative DNA damage1. One of the core principles that underlies DNA biosynthesis is the radical-mediated elimnation of H2O to deoxygenate ribonucleotides, an example of ‘spin-center shift’ (SCS)2, during which an alcohol C–O bond is cleaved, resulting in a carbon-centered radical intermediate. While SCS is a well-understood biochemical process, it is underutilized by the synthetic organic chemistry community. We wondered whether it would be possible to take advantage of this naturally occurring process to accomplish mild, non-traditional alkylations using alcohols as radical precursors. Considering traditional radical-based alkylation methods require the use of stoichiometric oxidants, elevated temperatures, or peroxides3–7, the development of a mild protocol using simple and abundant alkylating agents would have significant utility in the synthesis of diversely functionalized pharmacophores. In this manuscript, we describe the successful execution of this idea via the development of a dual catalytic alkylation of heteroarenes using alcohols as mild alkylating reagents. This method represents the first broadly applicable use of unactivated alcohols as latent alkylating reagents, achieved via the successful merger of photoredox and hydrogen atom transfer (HAT) catalysis. The utility of this multi-catalytic protocol has been demonstrated through the late-stage functionalization of the medicinal agents, fasudil and milrinone. PMID:26308895

Selected Alkylating Agents Can Overcome Drug Tolerance of G0-like Tumor Cells and Eradicate BRCA1-Deficient Mammary Tumors in Mice.

Science.gov (United States)

Pajic, Marina; Blatter, Sohvi; Guyader, Charlotte; Gonggrijp, Maaike; Kersbergen, Ariena; Küçükosmanoğlu, Aslι; Sol, Wendy; Drost, Rinske; Jonkers, Jos; Borst, Piet; Rottenberg, Sven

2017-11-15

Purpose: We aimed to characterize and target drug-tolerant BRCA1-deficient tumor cells that cause residual disease and subsequent tumor relapse. Experimental Design: We studied responses to various mono- and bifunctional alkylating agents in a genetically engineered mouse model for BRCA1/p53 -mutant breast cancer. Because of the large intragenic deletion of the Brca1 gene, no restoration of BRCA1 function is possible, and therefore, no BRCA1-dependent acquired resistance occurs. To characterize the cell-cycle stage from which Brca1 -/- ;p53 -/- mammary tumors arise after cisplatin treatment, we introduced the fluorescent ubiquitination-based cell-cycle indicator (FUCCI) construct into the tumor cells. Results: Despite repeated sensitivity to the MTD of platinum drugs, the Brca1 -mutated mammary tumors are not eradicated, not even by a frequent dosing schedule. We show that relapse comes from single-nucleated cells delaying entry into the S-phase. Such slowly cycling cells, which are present within the drug-naïve tumors, are enriched in tumor remnants. Using the FUCCI construct, we identified nonfluorescent G 0 -like cells as the population most tolerant to platinum drugs. Intriguingly, these cells are more sensitive to the DNA-crosslinking agent nimustine, resulting in an increased number of multinucleated cells that lack clonogenicity. This is consistent with our in vivo finding that the nimustine MTD, among several alkylating agents, is the most effective in eradicating Brca1 -mutated mouse mammary tumors. Conclusions: Our data show that targeting G 0 -like cells is crucial for the eradication of BRCA1/p53-deficient tumor cells. This can be achieved with selected alkylating agents such as nimustine. Clin Cancer Res; 23(22); 7020-33. ©2017 AACR . ©2017 American Association for Cancer Research.

SERIES: Genomic instability in cancer Balancing repair and tolerance of DNA damage caused by alkylating agents

Science.gov (United States)

Fu, Dragony; Calvo, Jennifer A.; Samson, Leona D

2013-01-01

Alkylating agents comprise a major class of frontline chemotherapeutic drugs that inflict cytotoxic DNA damage as their main mode of action, in addition to collateral mutagenic damage. Numerous cellular pathways, including direct DNA damage reversal, base excision repair (BER), and mismatch repair (MMR) respond to alkylation damage to defend against alkylation-induced cell death or mutation. However, maintaining a proper balance of activity both within and between these pathways is crucial for an organism's favorable response to alkylating agents. Furthermore, an individual's response to alkylating agents can vary considerably from tissue to tissue and from person to person, pointing to genetic and epigenetic mechanisms that modulate alkylating agent toxicity. PMID:22237395

Therapeutic potential of a non-steroidal bifunctional anti-inflammatory and anti-cholinergic agent against skin injury induced by sulfur mustard

Energy Technology Data Exchange (ETDEWEB)

Chang, Yoke-Chen; Wang, James D.; Hahn, Rita A.; Gordon, Marion K.; Joseph, Laurie B. [Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ (United States); Heck, Diane E. [Department of Environmental Science, New York Medical College, Valhalla, NY (United States); Heindel, Ned D. [Department of Chemistry, Lehigh University, Bethlehem, PA (United States); Young, Sherri C. [Department of Chemistry, Muhlenberg College, Allentown, PA (United States); Sinko, Patrick J. [Department of Pharmaceutics, Rutgers University, Piscataway, NJ (United States); Casillas, Robert P. [MRIGlobal, Kansas City, MO (United States); Laskin, Jeffrey D. [Environmental and Occupational Medicine, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ (United States); Laskin, Debra L. [Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ (United States); Gerecke, Donald R., E-mail: gerecke@eohsi.rutgers.edu [Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ (United States)

2014-10-15

Sulfur mustard (bis(2-chloroethyl) sulfide, SM) is a highly reactive bifunctional alkylating agent inducing edema, inflammation, and the formation of fluid-filled blisters in the skin. Medical countermeasures against SM-induced cutaneous injury have yet to be established. In the present studies, we tested a novel, bifunctional anti-inflammatory prodrug (NDH 4338) designed to target cyclooxygenase 2 (COX2), an enzyme that generates inflammatory eicosanoids, and acetylcholinesterase, an enzyme mediating activation of cholinergic inflammatory pathways in a model of SM-induced skin injury. Adult SKH-1 hairless male mice were exposed to SM using a dorsal skin vapor cup model. NDH 4338 was applied topically to the skin 24, 48, and 72 h post-SM exposure. After 96 h, SM was found to induce skin injury characterized by edema, epidermal hyperplasia, loss of the differentiation marker, keratin 10 (K10), upregulation of the skin wound marker keratin 6 (K6), disruption of the basement membrane anchoring protein laminin 322, and increased expression of epidermal COX2. NDH 4338 post-treatment reduced SM-induced dermal edema and enhanced skin re-epithelialization. This was associated with a reduction in COX2 expression, increased K10 expression in the suprabasal epidermis, and reduced expression of K6. NDH 4338 also restored basement membrane integrity, as evidenced by continuous expression of laminin 332 at the dermal–epidermal junction. Taken together, these data indicate that a bifunctional anti-inflammatory prodrug stimulates repair of SM induced skin injury and may be useful as a medical countermeasure. - Highlights: • Bifunctional anti-inflammatory prodrug (NDH4338) tested on SM exposed mouse skin • The prodrug NDH4338 was designed to target COX2 and acetylcholinesterase. • The application of NDH4338 improved cutaneous wound repair after SM induced injury. • NDH4338 treatment demonstrated a reduction in COX2 expression on SM injured skin. • Changes of skin repair

Synthesis and evaluation of novel caged DNA alkylating agents bearing 3,4-epoxypiperidine structure.

Science.gov (United States)

Kawada, Yuji; Kodama, Tetsuya; Miyashita, Kazuyuki; Imanishi, Takeshi; Obika, Satoshi

2012-07-14

Previously, we reported that the 3,4-epoxypiperidine structure, whose design was based on the active site of DNA alkylating antitumor antibiotics, azinomycins A and B, possesses prominent DNA cleavage activity. In this report, novel caged DNA alkylating agents, which were designed to be activated by UV irradiation, were synthesized by the introduction of four photo-labile protecting groups to a 3,4-epoxypiperidine derivative. The DNA cleavage activity and cytotoxicity of the caged DNA alkylating agents were examined under UV irradiation. Four caged DNA alkylating agents showed various degrees of bioactivity depending on the photosensitivity of the protecting groups.

An adaptive response to alkylating agents in Aspergillus nidulans.

Science.gov (United States)

Hooley, P; Shawcross, S G; Strike, P

1988-11-01

A simple method is described for demonstrating adaptation to alkylation damage in Aspergillus nidulans. One wild type, two MNNG-sensitive, and one MNNG-resistant strain all showed improvement in colony growth when challenged with MNNG following appropriate inducing pretreatments. Other alkylating agents (MMS, EMS) could also adapt mycelium to later MNNG challenge, while 4NQO and UV could not. The inducible effect was not transmissible through conidia. A standard reversion assay based upon methG proved impractical for studying mutation frequencies during alkylation treatments owing to variations in MNNG resistance amongst revertants.

Persistence of DNA adducts, hypermutation and acquisition of cellular resistance to alkylating agents in glioblastoma.

Science.gov (United States)

Head, R J; Fay, M F; Cosgrove, L; Y C Fung, K; Rundle-Thiele, D; Martin, J H

2017-12-02

Glioblastoma is a lethal form of brain tumour usually treated by surgical resection followed by radiotherapy and an alkylating chemotherapeutic agent. Key to the success of this multimodal approach is maintaining apoptotic sensitivity of tumour cells to the alkylating agent. This initial treatment likely establishes conditions contributing to development of drug resistance as alkylating agents form the O 6 -methylguanine adduct. This activates the mismatch repair (MMR) process inducing apoptosis and mutagenesis. This review describes key juxtaposed drivers in the balance between alkylation induced mutagenesis and apoptosis. Mutations in MMR genes are the probable drivers for alkylation based drug resistance. Critical to this interaction are the dose-response and temporal interactions between adduct formation and MMR mutations. The precision in dose interval, dose-responses and temporal relationships dictate a role for alkylating agents in either promoting experimental tumour formation or inducing tumour cell death with chemotherapy. Importantly, this resultant loss of chemotherapeutic selective pressure provides opportunity to explore novel therapeutics and appropriate combinations to minimise alkylation based drug resistance and tumour relapse.

Fractionated dose studies with X-rays and various alkylating agents in P388 mouse lymphoma cells

International Nuclear Information System (INIS)

Anderson, D.

1981-01-01

The fractionated dose technique has been used in P388F cells to examine the effects of X-rays and four alkylating agents on survival and induction of 5-iodo-2-deoxyuridine (IudR) resistant variants. Fractionation intervals up to 5 1/2 h were used for X-rays and for the alkylating agents up to 192 h. Fractionation of the X-ray dose resulted in a sparing effect for survival and variant induction. A sparing effect was also observed for survival after treatment with alkylating agents. However, variant frequencies were observed as large as or greater than those produced by the full doses of alkylating agents. For such agents this would suggest that survival and variant induction are independent events. Differences in the effects of X-rays and alkylating agents cannot be explained by differences in growth rate or the recovery of viability after treatment

Fractionated dose studies with X-rays and various alkylating agents in P388 mouse lymphoma cells

International Nuclear Information System (INIS)

Anderson, D.

1981-01-01

The fractionated dose technique was used in P388F cells to examine the effects of X-rays and four alkylating agents on survival and induction of 5-iodo-2-deoxyuridine (IudR) resistant variants. Fractionation intervals up to 51/2 h were used for X-rays and for the alkylating agents up to 192 h. Fractionation of the X-ray dose resulted in a sparing effect for survival and variant induction. A sparing effect was also observed for survival after treatment with alkylating agents. However, variant frequencies were observed as large as or greater than those produced by the full doses of alkylating agents. For such agents this would suggest that survival and variant induction are independent events. Differences in the effects of X-rays and alkylating agents cannot be explained by differences in growth rate or the recovery of viability after treatment. (author)

Cu(I)-Catalyzed Enantioselective Friedel-Crafts Alkylation of Indoles with 2-Aryl-N-sulfonylaziridines as Alkylating Agents.

Science.gov (United States)

Ge, Chen; Liu, Ren-Rong; Gao, Jian-Rong; Jia, Yi-Xia

2016-07-01

A highly enantioselective Friedel-Crafts alkylation of indoles with N-sulfonylaziridines as alkylating agents has been developed by utilizing the complex of Cu(CH3CN)4BF4/(S)-Segphos as a catalyst. A range of optically active tryptamine derivatives are obtained in good to excellent yields and enantioselectivities (up to >99% ee) via a kinetic resolution process.

Chemical structure of carbamoylating groups and their relationship to bone marrow toxicity and antiglioma activity of bifunctionally alkylating and carbamoylating nitrosoureas.

Science.gov (United States)

Ali-Osman, F; Giblin, J; Berger, M; Murphy, M J; Rosenblum, M L

1985-09-01

Although the antitumor effects of chloroethylnitrosoureas have been shown to be due primarily to DNA-DNA cross-linking by the alkylating moieties of these agents, the basis of the often accompanying bone marrow toxicity has been more controversial. We report on the relative bone marrow toxicity of four model nitrosoureas with different alkylating and carbamoylating activities: 1,3-bis(2-chloroethyl)-1-nitrosourea; 1,3-bis(trans-4-hydroxycyclohexyl)-1-nitrosourea; chlorozotozin, (2-[3-(2-chloroethyl)-3 -nitrosoureido]-2-deoxy-D-glucopyranose); and -3-(beta-D-glucopyranosyl)-1-nitrosourea. Inhibitions of DNA, RNA, and protein synthesis in murine bone marrow cells and of colony growth of myeloid precursor cells (granulocyte-macrophage colony-forming units) were used as in vitro end points of myelotoxicity. Further, we determined the antiglioma activity of the four nitrosoureas on two human gliomas in a clonogenic tumor cell assay and studied the effect of the non-nitrosourea carbamoylators potassium cyanate, chloroethyl isocyanate, cyclohexyl isocyanate, ethyl isocyanate, and ethyl isothiocyanate on granulocyte-macrophage colony-forming units. The results show that, at equivalent drug exposures, clonogenic glioma cell kill was significant and comparative for 1,3-bis(2-chloroethyl)-1-nitrosourea, 1-(2-chloroethyl)-3-(beta-D-glucopyranosyl)-1-nitrosourea, and chlorozotocin; 1,3-bis(trans-4-hydroxycyclohexyl)-1-nitrosourea showed little activity. In contrast, granulocyte-macrophage colony-forming unit toxicity was low with chlorozotocin and 1-(2-chloroethyl)-3-(beta-D-glucopyranosyl)-1-nitrosourea and very high with 1,3-bis(2-chloroethyl)-1-nitrosourea and 1,3-bis(trans-4-hydroxycyclohexyl)-1-nitrosourea. Of the isocyanates, bone marrow toxicity was highest with chloroethyl isocyanate and cyclohexyl isocyanate, intermediate with ethyl isocyanate, and lowest with KOCN and ethyl isothiocyanate. Our results indicate that (a) bifunctional alkylation is essential for

Balancing repair and tolerance of DNA damage caused by alkylating agents

OpenAIRE

Fu, Dragony; Calvo, Jennifer A.; Samson, Leona D.

2012-01-01

Alkylating agents constitute a major class of frontline chemotherapeutic drugs that inflict cytotoxic DNA damage as their main mode of action, in addition to collateral mutagenic damage. Numerous cellular pathways, including direct DNA damage reversal, base excision repair (BER) and mismatch repair (MMR), respond to alkylation damage to defend against alkylation-induced cell death or mutation. However, maintaining a proper balance of activity both within and between these pathways is crucial ...

Pharmacology of dimethanesulfonate alkylating agents: busulfan and treosulfan.

Science.gov (United States)

Galaup, Ariane; Paci, Angelo

2013-03-01

Among the dimethanesulfonates, busulfan, in combination with other alkylating agents or nucleoside analogues, is the cornerstone of high-dose chemotherapy. It is used, and followed hematopoietic stem cell transplantation, for the treatment of various hematologic malignancies and immunodeficiencies. Treosulfan, which is a hydrophilic analogue of busulfan, was the first dimethanesufonate registered for the treatment of ovarian cancer. Recently, treosulfan has been investigated for the treatment of hematologic malignancies in combination with the same second agents before hematopoietic stem cell transplantation. This work reviews the pharmacological data of these two dimethanesulfonates alkylating agents. Specifically, the article looks at their chemistry, metabolism, anticancer activity, and their pharmacokinetics and pharmacodynamics. Busulfan has been investigated widely for more than three decades leading to a large and precise handling of this agent with numerous studies on activity and pharmacokinetics and pharmacodynamics. In contrast, the behavior of treosulfan is still under investigation and not fully described. The complexity of treosulfan's metabolism and mechanism of action gives rise to the need of a deeper understanding of its pharmacological activity in a context of high-dose chemotherapy. Specifically, there is a great need to better understand its pharmacokinetics/pharmacodynamics relationship.

Self-organization of Au–CdSe hybrid nanoflowers at different length scales via bi-functional diamine linkers

Energy Technology Data Exchange (ETDEWEB)

AbouZeid, Khaled Mohamed [Virginia Commonwealth University, Department of Chemistry (United States); Mohamed, Mona Bakr [Cairo University, National Institute of Laser Enhanced Science (NILES) (Egypt); El-Shall, M. Samy, E-mail: mselshal@vcu.edu [Virginia Commonwealth University, Department of Chemistry (United States)

2016-01-15

This work introduces a series of molecular bridging bi-functional linkers to produce laterally self-assembled nanostructures of the Au–CdSe nanoflowers on different length scales ranging from 10 nm to 100 microns. Assembly of Au nanocrystals within amorphous CdSe rods is found in the early stages of the growth of the Au–CdSe nanoflowers. The Au–CdSe nanoflowers are formed through a one-pot low temperature (150 °C) process where CdSe clusters are adsorbed on the surface of the Au cores, and they then start to form multiple arms and branches resulting in flower-shaped hybrid nanostructures. More complex assembly at a micron length scale can be achieved by means of bi-functional capping agents with appropriate alkyl chain lengths, such as 1,12-diaminododecane.

Alkylating agent (MNU)-induced mutation in space environment

Science.gov (United States)

Ohnishi, T.; Takahashi, A.; Ohnishi, K.; Takahashi, S.; Masukawa, M.; Sekikawa, K.; Amano, T.; Nakano, T.; Nagaoka, S.

2001-01-01

In recent years, some contradictory data about the effects of microgravity on radiation-induced biological responses in space experiments have been reported. We prepared a damaged template DNA produced with an alkylating agent (N-methyl-N-nitroso urea; MNU) to measure incorrect base-incorporation during DNA replication in microgravity. We examined whether mutation frequency is affected by microgravity during DNA replication for a DNA template damaged by an alkylating agent. Using an in vitro enzymatic reaction system, DNA synthesis by Taq polymerase or polymerase III was done during a US space shuttle mission (Discovery, STS-91). After the flight, DNA replication and mutation frequencies were measured. We found that there was almost no effect of microgravity on DNA replication and mutation frequency. It is suggested that microgravity might not affect at the stage of substrate incorporation in induced-mutation frequency.

Alkylsilyl Peroxides as Alkylating Agents in the Copper-Catalyzed Selective Mono-N-Alkylation of Primary Amides and Arylamines.

Science.gov (United States)

Sakamoto, Ryu; Sakurai, Shunya; Maruoka, Keiji

2017-07-06

The copper-catalyzed selective mono-N-alkylation of primary amides or arylamines using alkylsilyl peroxides as alkylating agents is reported. The reaction proceeds under mild reaction conditions and exhibits a broad substrate scope with respect to the alkylsilyl peroxides, as well as to the primary amides and arylamines. Mechanistic studies suggest that the present reaction should proceed through a free-radical process that includes alkyl radicals generated from the alkylsilyl peroxides. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The effect of alkylating agents on model supported metal clusters

Energy Technology Data Exchange (ETDEWEB)

Erdem-Senatalar, A.; Blackmond, D.G.; Wender, I. (Pittsburgh Univ., PA (USA). Dept. of Chemical and Petroleum Engineering); Oukaci, R. (CERHYD, Algiers (Algeria))

1988-01-01

Interactions between model supported metal clusters and alkylating agents were studied in an effort to understand a novel chemical trapping technique developed for identifying species adsorbed on catalyst surfaces. It was found that these interactions are more complex than had previously been suggested. Studies were completed using deuterium-labeled dimethyl sulfate (DMS), (CH{sub 3}){sub 2}SO{sub 4}, as a trapping agent to interact with the supported metal cluster ethylidyne tricobalt enneacarbonyl. Results showed that oxygenated products formed during the trapping reaction contained {minus}OCD{sub 3} groups from the DMS, indicating that the interaction was not a simple alkylation. 18 refs., 1 fig., 3 tabs.

The clinical pharmacology of alkylating agents in high-dose chemotherapy

NARCIS (Netherlands)

Huitema, A. D.; Smits, K. D.; Mathôt, R. A.; Schellens, J. H.; Rodenhuis, S.; Beijnen, J. H.

2000-01-01

Alkylating agents are widely used in high-dose chemotherapy regimens in combination with hematological support. Knowledge about the pharmacokinetics and pharmacodynamics of these agents administered in high doses is critical for the safe and efficient use of these regimens. The aim of this review is

S - and N-alkylating agents diminish the fluorescence of fluorescent dye-stained DNA.

Science.gov (United States)

Giesche, Robert; John, Harald; Kehe, Kai; Schmidt, Annette; Popp, Tanja; Balzuweit, Frank; Thiermann, Horst; Gudermann, Thomas; Steinritz, Dirk

2017-01-25

Sulfur mustard (SM), a chemical warfare agent, causes DNA alkylation, which is believed to be the main cause of its toxicity. SM DNA adducts are commonly used to verify exposure to this vesicant. However, the required analytical state-of-the-art mass-spectrometry methods are complex, use delicate instruments, are not mobile, and require laboratory infrastructure that is most likely not available in conflict zones. Attempts have thus been made to develop rapid detection methods that can be used in the field. The analysis of SM DNA adducts (HETE-G) by immunodetection is a convenient and suitable method. For a diagnostic assessment, HETE-G levels must be determined in relation to the total DNA in the sample. Total DNA can be easily visualized by the use of fluorescent DNA dyes. This study examines whether SM and related compounds affect total DNA staining, an issue that has not been investigated before. After pure DNA was extracted from human keratinocytes (HaCaT cells), DNA was exposed to different S- and N-alkylating agents. Our experiments revealed a significant, dose-dependent decrease in the fluorescence signal of fluorescent dye-stained DNA after exposure to alkylating agents. After mass spectrometry and additional fluorescence measurements ruled out covalent modifications of ethidium bromide (EthBr) by SM, we assumed that DNA crosslinks caused DNA condensation and thereby impaired access of the fluorescent dyes to the DNA. DNA digestion by restriction enzymes restored fluorescence, a fact that strengthened our hypothesis. However, monofunctional agents, which are unable to crosslink DNA, also decreased the fluorescence signal. In subsequent experiments, we demonstrated that protons produced during DNA alkylation caused a pH decrease that was found responsible for the reduction in fluorescence. The use of an appropriate buffer system eliminated the adverse effect of alkylating agents on DNA staining with fluorescent dyes. An appropriate buffer system is thus

Nitric oxide donors attenuate clongenic potential in rat C6 glioma cells treated with alkylating chemotherapeutic agents.

Science.gov (United States)

Yang, Jir-Jei; Yin, Jiu-Haw; Yang, Ding-I

2007-05-11

1,3-Bis(2-chloroethyl)-1-nitrosourea (BCNU) kills tumor cells via multiple actions including alkylation and carbamoylation. Previously, we have reported that formation of S-nitrosoglutathione (GSNO) in glioma cells overexpressing inducible nitric oxide synthase (iNOS) contributed to nitric oxide (NO)-dependent carbamoylating chemoresistance against BCNU. To further characterize the effects of NO on alkylating cytotoxicity, colony formation assay was applied to evaluate the effects of various NO donors on rat C6 glioma cells challenged with alkylating agents. We demonstrate that NO donors including GSNO, diethylamine NONOate (DEA/NO), and sodium nitroprusside (SNP) substantially reduced the extent of colony formation in glioma cells treated with alkylating agents, namely methyl methanesulfonate (MMS), N-methyl-N-nitrosourea (MNU), and N-ethyl-N-nitrosourea (ENU). Without alkylating agents these NO-releasing agents alone had no effects on clongenic potential of rat C6 glioma cells. Among these three NO donors used, the effectiveness in potentiating alkylating cytotoxicity is in the order of "GSNO>DEA/NO>SNP" when applied at the same dosages. GSNO also exerted similar synergistic actions reducing the extents of colony formation when co-administrated with 1,2-bis(methylsulfonyl)-1-(2-chloroethyl)-hydrazine (compound #1), another alkylating agent that mimics the chloroethylating action of BCNU. Together with our previous findings, we propose that NO donors may be used as adjunct chemotherapy with alkylating agents for such malignant brain tumors as glioblastoma multiforme (GBM). In contrast, production of NO as a result of iNOS induction, such as that occurring after surgical resection of brain tumors, may compromise the efficacy of carbamoylating chemotherapy.

Effects of alkylating agents on dopamine D(3) receptors in rat brain: selective protection by dopamine.

Science.gov (United States)

Zhang, K; Weiss, N T; Tarazi, F I; Kula, N S; Baldessarini, R J

1999-11-13

Dopamine D(3) receptors are structurally highly homologous to other D(2)-like dopamine receptors, but differ from them pharmacologically. D(3) receptors are notably resistant to alkylation by 1-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ), which readily alkylates D(2) receptors. We compared EEDQ with N-(p-isothiocyanatophenethyl)spiperone (NIPS), a selective D(2)-like receptor alkylating agent, for effects on D(3) and D(2) receptors in rat brain using autoradiographic analysis. Neither agent occluded D(3) receptors in vivo at doses that produced substantial blockade of D(2) receptors, even after catecholamine-depleting pretreatments. In vitro, however, D(3) receptors were readily alkylated by both NIPS (IC(50)=40 nM) and EEDQ (IC(50)=12 microM). These effects on D(3) sites were blocked by nM concentrations of dopamine, whereas microM concentrations were required to protect D(2) receptors from the alkylating agents. The findings are consistent with the view that alkylation of D(3) receptors in vivo is prevented by its high affinity for even minor concentrations of endogenous dopamine.

Quinone methides tethered to naphthalene diimides as selective G-quadruplex alkylating agents.

Science.gov (United States)

Di Antonio, Marco; Doria, Filippo; Richter, Sara N; Bertipaglia, Carolina; Mella, Mariella; Sissi, Claudia; Palumbo, Manlio; Freccero, Mauro

2009-09-16

We have developed novel G-quadruplex (G-4) ligand/alkylating hybrid structures, tethering the naphthalene diimide moiety to quaternary ammonium salts of Mannich bases, as quinone-methide precursors, activatable by mild thermal digestion (40 degrees C). The bis-substituted naphthalene diimides were efficiently synthesized, and their reactivity as activatable bis-alkylating agents was investigated in the presence of thiols and amines in aqueous buffered solutions. The electrophilic intermediate, quinone-methide, involved in the alkylation process was trapped, in the presence of ethyl vinyl ether, in a hetero Diels-Alder [4 + 2] cycloaddition reaction, yielding a substituted 2-ethoxychroman. The DNA recognition and alkylation properties of these new derivatives were investigated by gel electrophoresis, circular dichroism, and enzymatic assays. The alkylation process occurred preferentially on the G-4 structure in comparison to other DNA conformations. By dissecting reversible recognition and alkylation events, we found that the reversible process is a prerequisite to DNA alkylation, which in turn reinforces the G-quadruplex structural rearrangement.

Design of novel antitumor DNA alkylating agents: the benzacronycine series.

Science.gov (United States)

David-Cordonnier, Marie-Hélène; Laine, William; Gaslonde, Thomas; Michel, Sylvie; Tillequin, Francois; Koch, Michel; Léonce, Stéphane; Pierré, Alain; Bailly, Christian

2004-03-01

Acronycine, a natural alkaloid originally extracted from the bark of the Australian ash scrub Acronychia baueri, has shown a significant antitumor activity in animal models. Acronycine has been tested against human cancers in the early 1980s, but the clinical trials showed modest therapeutic effects and its development was rapidly discontinued. In order to optimize the antineoplastic effect, different benzoacronycine derivatives were synthesized. Among those, the di-acetate compound S23906-1 was recently identified as a promising anticancer drug candidate and a novel alkylating agent specifically reacting with the exocylic 2-NH2 group of guanines in DNA. The study of DNA bonding capacity of acronycine derivatives leads to the identification of the structural requirements for DNA alkylation. In nearly all cases, the potent alkylating agents, such as S23906-1, were found to be much more cytotoxic than the unreactive analogs such as acronycine itself or diol derivatives. Alkylation of DNA by the monoacetate derivative S28687-1, which is a highly reactive hydrolysis metabolite of S23906-1, occurs with a marked preference for the N2 position of guanine. Other bionucleophiles can react with S23906-1. The benzacronycine derivatives, which efficiently alkylate DNA, also covalently bind to the tripeptide glutathione (GSH) but not to the oxidized product glutathione disulfide. Here we review the reactivity of S23906-1 and some derivatives toward DNA and GSH. The structure-activity relationships in the benzacronycine series validate the reaction mechanism implicating DNA as the main molecular target. S23906-1 stands as the most promising lead of a medicinal chemistry program aimed at discovering novel antitumor drugs based on the acronycine skeleton.

The Impact of Commonly Used Alkylating Agents on Artifactual Peptide Modification.

Science.gov (United States)

Hains, Peter G; Robinson, Phillip J

2017-09-01

Iodoacetamide is by far the most commonly used agent for alkylation of cysteine during sample preparation for proteomics. An alternative, 2-chloroacetamide, has recently been suggested to reduce the alkylation of residues other than cysteine, such as the N-terminus, Asp, Glu, Lys, Ser, Thr, and Tyr. Here we show that although 2-chloroacetamide reduces the level of off-target alkylation, it exhibits a range of adverse effects. The most significant of these is methionine oxidation, which increases to a maximum of 40% of all Met-containing peptides, compared with 2-5% with iodoacetamide. Increases were also observed for mono- and dioxidized tryptophan. No additional differences between the alkylating reagents were observed for a range of other post-translational modifications and digestion parameters. The deleterious effects were observed for 2-chloroacetamide from three separate suppliers. The adverse impact of 2-chloroacetamide on methionine oxidation suggests that it is not the ideal alkylating reagent for proteomics.

DNA Damage Induced by Alkylating Agents and Repair Pathways

OpenAIRE

Natsuko Kondo; Akihisa Takahashi; Koji Ono; Takeo Ohnishi

2010-01-01

The cytotoxic effects of alkylating agents are strongly attenuated by cellular DNA repair processes, necessitating a clear understanding of the repair mechanisms. Simple methylating agents form adducts at N- and O-atoms. N-methylations are removed by base excision repair, AlkB homologues, or nucleotide excision repair (NER). O 6-methylguanine (MeG), which can eventually become cytotoxic and mutagenic, is repaired by O 6-methylguanine-DNA methyltransferase, and O 6MeG:T mispairs are recognized...

Nature of chromosome gaps induced by alkylating agents and γ-rays as revealed by caffeine treatment

International Nuclear Information System (INIS)

Dimitrov, B.

1981-01-01

In the cells of primary roots of Crepis capillaris, post-treatment with caffeine increased the frequency of gaps and chromosomal aberrations induced by the alkylating agents ethyleneimine and N-nitroso-N-methylurethane and γ-rays. The increase in the frequency of gaps was considerably lower than that observed in chromosomal aberrations, this being more strongly expressed in the case fo the alkylating agents. The potentiating effect of caffeine on the γ-ray-induced chromosomal gaps was a little higher in S as compared in G 2 . These results lead to the conclusion that the alkylating agents and the γ-rays might induce 2 types of chromosomal gap. (orig.)

Rituximab, alkylating agents or combination therapy for gastric mucosa-associated lymphoid tissue lymphoma: a monocentric non-randomised observational study.

Science.gov (United States)

Amiot, A; Lévy, M; Copie-Bergman, C; Dupuis, J; Szablewski, V; Le Baleur, Y; Baia, M; Belhadj, K; Sobhani, I; Leroy, K; Haioun, C; Delchier, J-C

2014-03-01

There is no consensus on the standard treatment of gastric mucosa-associated lymphoid tissue (MALT) lymphoma for Helicobacter pylori-negative patients and for patients with persistent disease despite H. pylori eradication. To evaluate the comparative efficacy and safety of alkylating agents and rituximab alone or in combination. In this monocentric retrospective study, which included 106 patients who had not been previously treated with anti-cancer agents, we evaluated the efficacy and safety of oral alkylating agents monotherapy (n = 48), rituximab monotherapy (n = 28) and the therapy combining both drugs (n = 30). Evaluations were performed at weeks 6 (W6), 25 (W25), and 52 (W52) and after 2 years (W104). After a median follow-up period of 4.9 years (range 0.4-17.2 years), complete remission and overall response were significantly higher in patients in the combination therapy group at W104 (92% and 100% respectively) compared with patients treated with alkylating agents alone (66% and 68%) and rituximab alone (64% and 73%). The 5-year progression-free survival probabilities were 68%, 70% and 89% in patients treated with alkylating agents alone, rituximab alone and combination therapy respectively. Haematological adverse events were reported in 32 (30%) patients (mostly grade 1) and were more frequent in the two groups receiving alkylating agents (P = 0.05 and P alkylating agents alone. Rituximab has a better safety profile than regimens containing alkylating agents. © 2014 John Wiley & Sons Ltd.

Cytotoxicity of alkylating agents towards sensitive and resistant strains of Escherichia coli in relation to extent and mode of alkylation of cellular macromolecules and repair of alkylation lesions in deoxyribonucleic acids.

Science.gov (United States)

Lawley, P D; Brookes, P

1968-09-01

1. A quantitative study was made of the relationship between survival of colony-forming ability in Escherichia coli strains B/r and B(s-1) and the extents of alkylation of cellular DNA, RNA and protein after treatment with mono- or di-functional sulphur mustards, methyl methanesulphonate or iodoacetamide. 2. The mustards and methyl methanesulphonate react with nucleic acids in the cells, in the same way as found previously from chemical studies in vitro, and with proteins. Iodoacetamide reacts only with protein, principally with the thiol groups of cysteine residues. 3. The extents of alkylation of cellular constituents required to prevent cell division vary widely according to the strain of bacteria and the nature of the alkylating agent. 4. The extents of alkylation of the sensitive and resistant strains at a given dose of alkylating agent do not differ significantly. 5. Removal of alkyl groups from DNA of cells of the resistant strains B/r and 15T(-) after alkylation with difunctional sulphur mustard was demonstrated; the product di(guanin-7-ylethyl) sulphide, characteristic of di- as opposed to mono-functional alkylation, was selectively removed; the time-scale of this effect suggests an enzymic rather than a chemical mechanism. 6. The sensitive strain B(s-1) removed alkyl groups from DNA in this way only at very low extents of alkylation. When sensitized to mustard action by treatment with iodoacetamide, acriflavine or caffeine, the extent of alkylation of cellular DNA corresponding to a mean lethal dose was decreased to approximately 3 molecules of di(guanin-7-ylethyl) sulphide in the genome of this strain. 7. Relatively large numbers of monofunctional alkylations per genome can be withstood by this sensitive strain. Iodoacetamide had the weakest cytotoxic action of the agents investigated; methyl methanesulphonate was significantly weaker in effect than the monofunctional sulphur mustard, which was in turn weaker than the difunctional sulphur mustard. 8

The human cyclin B1 protein modulates sensitivity of DNA mismatch repair deficient prostate cancer cell lines to alkylating agents.

Science.gov (United States)

Rasmussen, L J; Rasmussen, M; Lützen, A; Bisgaard, H C; Singh, K K

2000-05-25

DNA damage caused by alkylating agents results in a G2 checkpoint arrest. DNA mismatch repair (MMR) deficient cells are resistant to killing by alkylating agents and are unable to arrest the cell cycle in G2 phase after alkylation damage. We investigated the response of two MMR-deficient prostate cancer cell lines DU145 and LNCaP to the alkylating agent MNNG. Our studies reveal that DU145 cancer cells are more sensitive to killing by MNNG than LNCaP. Investigation of the underlying reasons for lower resistance revealed that the DU145 cells contain low endogenous levels of cyclin B1. We provide direct evidence that the endogenous level of cyclin B1 modulates the sensitivity of MMR-deficient prostate cancer cells to alkylating agents.

Stimulatory and protective effects of alkylating agents applied in ultra-low concentrations.

Science.gov (United States)

Pukhalsky, A L; Shmarina, G V

2001-01-01

Alkylating drugs belonging to the nitrogen mustard family are known as cytostatic and immunosuppressive agents. Ultra-low doses of these drugs may demonstrate pharmacological effects unlike this category of drugs. In the case of a gradual dose decrease, the number of targets for alkylation is also reduced and the drug switches from cytostatic to cell growth modifier. We postulate that application of ultra-low doses of alkylating drugs may result in a beneficial effect in the therapy of diseases associated with chronic inflammation of the mucosa, especially with the signs of epithelial atrophy. Copyright 2001 S. Karger AG, Basel

Nearest neighbor affects G:C to A:T transitions induced by alkylating agents.

OpenAIRE

Glickman, B W; Horsfall, M J; Gordon, A J; Burns, P A

1987-01-01

The influence of local DNA sequence on the distribution of G:C to A:T transitions induced in the lacI gene of E. coli by a series of alkylating agents has been analyzed. In the case of nitrosoguanidine, two nitrosoureas and a nitrosamine, a strong preference for mutation at sites proceeded 5' by a purine base was noted. This preference was observed with both methyl and ethyl donors where the predicted common ultimate alkylating species is the alkyl diazonium ion. In contrast, this preference ...

Effects of Photo-chemically Activated Alkylating Agents of the FR900482 Family on Chromatin

OpenAIRE

Subramanian, Vidya; Ducept, Pascal; Williams, Robert M.; Luger, Karolin

2007-01-01

Bioreductive alkylating agents are an important class of clinical antitumor antibiotics that cross-link and mono-alkylate DNA. Here we use a synthetic photochemically activated derivative of FR400482 to investigate the molecular mechanism of this class of drugs in a biologically relevant context. We find that the organization of DNA into nucleosomes effectively protects it against drug-mediated cross-linking, while permitting mono-alkylation. This modification has the potential to form covale...

CC-1065 and the duocarmycins: unraveling the keys to a new class of naturally derived DNA alkylating agents.

Science.gov (United States)

Boger, D L; Johnson, D S

1995-01-01

Key studies defining the DNA alkylation properties and selectivity of a new class of exceptionally potent, naturally occurring antitumor antibiotics including CC-1065, duocarmycin A, and duocarmycin SA are reviewed. Recent studies conducted with synthetic agents containing deep-seated structural changes and the unnatural enantiomers of the natural products and related analogs have defined the structural basis for the sequence-selective alkylation of duplex DNA and fundamental relationships between chemical structure, functional reactivity, and biological properties. The agents undergo a reversible, stereoelectronically controlled adenine-N3 addition to the least substituted carbon of the activated cyclopropane within selected AT-rich sites. The preferential AT-rich non-covalent binding selectivity of the agents within the narrower, deeper AT-rich minor groove and the steric accessibility to the alkylation site that accompanies deep AT-rich minor groove penetration control the sequence-selective DNA alkylation reaction and stabilize the resulting adduct. For the agents that possess sufficient reactivity to alkylate DNA, a direct relationship between chemical or functional stability and biological potency has been defined. Images Fig. 1 Fig. 2 PMID:7731958

Oncometabolite D-2-Hydroxyglutarate Inhibits ALKBH DNA Repair Enzymes and Sensitizes IDH Mutant Cells to Alkylating Agents.

Science.gov (United States)

Wang, Pu; Wu, Jing; Ma, Shenghong; Zhang, Lei; Yao, Jun; Hoadley, Katherine A; Wilkerson, Matthew D; Perou, Charles M; Guan, Kun-Liang; Ye, Dan; Xiong, Yue

2015-12-22

Chemotherapy of a combination of DNA alkylating agents, procarbazine and lomustine (CCNU), and a microtubule poison, vincristine, offers a significant benefit to a subset of glioma patients. The benefit of this regimen, known as PCV, was recently linked to IDH mutation that occurs frequently in glioma and produces D-2-hydroxyglutarate (D-2-HG), a competitive inhibitor of α-ketoglutarate (α-KG). We report here that D-2-HG inhibits the α-KG-dependent alkB homolog (ALKBH) DNA repair enzymes. Cells expressing mutant IDH display reduced repair kinetics, accumulate more DNA damages, and are sensitized to alkylating agents. The observed sensitization to alkylating agents requires the catalytic activity of mutant IDH to produce D-2-HG and can be reversed by the deletion of mutant IDH allele or overexpression of ALKBH2 or AKLBH3. Our results suggest that impairment of DNA repair may contribute to tumorigenesis driven by IDH mutations and that alkylating agents may merit exploration for treating IDH-mutated cancer patients. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Synthesis of novel bifunctional chelators and their use in preparing monoclonal antibody conjugates for tumor targeting

International Nuclear Information System (INIS)

Westerberg, D.A.; Carney, P.L.; Rogers, P.E.; Kline, S.J.; Johnson, D.K.

1989-01-01

Bifunctional derivatives of the chelating agents ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid, in which a p-isothiocyanatobenzyl moiety is attached at the methylene carbon atom of one carboxymethyl arm, was synthesized by reductive alkylation of the relevant polyamine with (p-nitrophenyl)pyruvic acid followed by carboxymethylation, reduction of the nitro group, and reaction with thiophosgene. The resulting isothiocyanate derivatives reacted with monoclonal antibody B72.3 to give antibody-chelator conjugates containing 3 mol of chelator per mole of immunoglobulin, without significant loss of immunological activity. Such conjugates, labeled with the radioisotopic metal indium-111, selectively bound a human colorectal carcinoma implanted in nude mice when given intravenously. Uptake into normal tissues was comparable to or lower than that reported for analogous conjugates with known bifunctional chelators. It is concluded that substitution with a protein reactive group at this position in polyaminopolycarboxylate chelators does not alter the chelating properties of these molecules to a sufficient extent to adversely affect biodistribution and thus provides a general method for the synthesis of such chelators

N-alkylvaline levels in globin as a new type of biomarker in risk assessment of alkylating agents.

Science.gov (United States)

Lewalter, J

1996-01-01

Adducts with the N-terminal valine of erythrocyte globin can serve as individual biomarkers of systemic and cellular exposure to endogenous and exogenous alkylating agents. In contrast to "detoxification markers" of this kind of mecapturic acids derived from alkylation of glutathione, individual N-alkylations of valine in globin reflect the formally "toxifying" part of the stress due to alkylating agents transformed into the ultimate toxicant. Thus, in contrast to the traditional methods of biological monitoring this approach enables a better evaluation of systemic exposure to reactive agents, adapted more sensibly to the exposure situation over the whole life span of erythrocytes, and it can serve as a specific biomarker of exposure for the purpose of health surveillance in occupational medicine. An individual evaluation of exposures in comparison with the range of corresponding background levels is discussed from the point of view of supplementary risk assessment in medical surveillance of occupationally exposed persons.

Inhibitors of poly (ADP-ribose) polymerase and their enhancement of alkylating agent cytotoxicity in vivo

International Nuclear Information System (INIS)

Horsman, M.R.; Brown, D.M.; Hirst, D.G.; Brown, J.M.

1984-01-01

The chromosomal enzyme poly (ADP-ribose) polymerase (ADPRP) is involved in the repair of DNA damage caused by both ionizing radiation and alkylating agents. The authors have shown that certain inhibitors of this enzyme decrease potentially lethal damage repair after X-rays. The aim of the present study was to investigate the possible enhancement of alkylating agent damage in vivo by several of these ADPRP inhibitors. 3-aminobenzamide (200 mg/kg), caffeine (200 mg/kg), or nicotinamide (1000 mg/kg) given to RIF-1-tumor-bearing mice immediately before a dose of melphalan (L-PAM) (8 mg/kg) produced enhancement of tumor response as demonstrated by an in vivo in vitro tumor excision assay. Caffeine and nicotinamide provided the greatest enhancement of L-PAM cytotoxicity with at least a 100-fold increase in killing. Data are presented on the mechanism by which these drugs and other more potent inhibitors enhance the tumor cell killing by L-PAM and other alkylating agents

A powerful selection assay for mixture libraries of DNA alkylating agents.

Science.gov (United States)

Ham, Young-Wan; Boger, Dale L

2004-08-04

A simple and powerful selection assay that permits the separation (rpHPLC), quantitation (ELSD), and identification (ESI-MS) of thermally released adenine adducts derived from duocarmycin analogues is detailed that can establish the most effective DNA alkylating agents in synthetic combinatorial mixtures.

Novel 3-nitrotriazole-based amides and carbinols as bifunctional anti-Chagasic agents

Science.gov (United States)

Papadopoulou, Maria V.; Bloomer, William D.; Lepesheva, Galina I.; Rosenzweig, Howard S.; Kaiser, Marcel; Aguilera-Venegas, Benjamín; Wilkinson, Shane R.; Chatelain, Eric; Ioset, Jean-Robert

2015-01-01

3-Nitro-1H-1,2,4-triazole-based amides with a linear, rigid core and 3-nitrotriazole-based fluconazole analogs were synthesized as dual functioning antitrypanosomal agents. Such compounds are excellent substrates for type I nitroreductase (NTR) located in the mitochondrion of trypanosomatids and, at the same time, act as inhibitors of the sterol 14α-demethylase (T. cruzi CYP51) enzyme. Because combination treatments against parasites are often superior to monotherapy, we believe that this emerging class of bifunctional compounds may introduce a new generation of antitrypanosomal drugs. In the present work, the synthesis and in vitro and in vivo evaluation of such compounds is discussed. PMID:25580906

Preparation of Ga-67 labeled monoclonal antibodies using deferoxamine as a bifunctional chelating agent

International Nuclear Information System (INIS)

Endo, K.; Furukawa, T.; Ohmomo, Y.

1984-01-01

Ga-67 labeled monoclonal IgG or F(ab')/sub 2/ fragments against α-fetoprotein and β-subunit of human choriogonadotropin (HCG), were prepared using Deferoxamine (DFO) as a bifunctional chelating agent. DFO, a well-known iron chelating agent, was conjugated with monoclonal antibodies (Ab) by a glutaraldehyde two step method and the effect of conjugation on the Ab activities was examined by RIA and Scatchard plot analysis. In both monoclonal Ab preparations, the conjugation reaction was favored as the pH increased. However, Ab-binding activities decreased as the molecular ratios of DFO to Ab increased. Preserved Ab activities were observed when Ab contained DFO per Ab molecule less than 2.1. At a ratio of over 3.3 DFO molecules per Ab, the maximal binding capacity rather than the affinity constant decreased. The inter-molecular cross linkage seemed to be responsible for the deactivation of binding activities. The obtained DFO-Ab conjugates, were then easily labeled with high efficiency and reproducibility and Ga-67 DFO-Ab complexes were highly stable both in vitro and in vivo. Thus, biodistribution of Ga-67 labeled F(ab')/sub 2/ fragments of monoclonal Ab to HCG β-subunit was attempted in nude mice transplanted with HCG-producing human teratocarcinoma. Tumor could be visualized, in spite of relatively high background imaging of liver, kidney and spleen. The use of DFO as a bifunctional chelating agent provided good evidence for its applicability to labeling monoclonal Ab with almost full retention of Ab activities. Further, availability of Ga-68 will make Ga-68 DFO-monoclonal Ab a very useful tool for positron tomography imaging of various tumors

HTB140 melanoma cells under proton irradiation and/or alkylating agents

Science.gov (United States)

Korićanac, L.; Petrović, I.; Privitera, G.; Cuttone, G.; Ristić-Fira, A.

2007-09-01

Chemoresistance is a major problem in the treatment of malignant melanoma. The mainstay of treatment for melanoma is the DNA-alkylating agent dacarbazine (DTIC). Fotemustine (FM), a member of the chloroethylnitrosourea group of alkylating agents, has also demonstrated significant antitumor effects in malignant melanoma. However, the intrinsic and acquired resistance of melanoma limits the clinical application of these drugs. Melanomas are also extremely radioresistant. With the objective of enhancing growth inhibition of melanoma cells, combined treatments of FM or DTIC with proton irradiation have been investigated. These effects were studied on HTB140 melanoma cell viability and proliferation. Cells exposed to treatment with FM and protons have shown inhibition of cell growth and significant reduction of proliferation capacity compared to single irradiation or drug treatment. Treatment with DTIC and protons has shown improved growth inhibition compared to appropriate single drug treatment, while the effects of single proton irradiation have been the most pronounced.

Synthesis and evaluation of sequence-specific DNA alkylating agents: effect of alkylation subunits.

Science.gov (United States)

Shimizu, Tatsuhiko; Sasaki, Shunta; Minoshima, Masafumi; Shinohara, Ken-ichi; Bando, Toshikazu; Sugiyama, Hiroshi

2006-01-01

We have demonstrated that hairpin pyrrole (Py)- imidazole (Im) polyamide-CBI conjugates selectively alkylate predetermined sequences. In this study, we investigated the effect of alkylation subunits, for example conjugates 1-4 with three types of DNA alkylating units, and Py-Im polyamides with indole linker. Conjugate 3 and 4 selectively alkylated the predetermined sequences as described previously, while conjugates 1 and 2 alkylate at mismatched sites.

The aminoindanol core as a key scaffold in bifunctional organocatalysts

Directory of Open Access Journals (Sweden)

Isaac G. Sonsona

2016-03-01

Full Text Available The 1,2-aminoindanol scaffold has been found to be very efficient, enhancing the enantioselectivity when present in organocatalysts. This may be explained by its ability to induce a bifunctional activation of the substrates involved in the reaction. Thus, it is easy to find hydrogen-bonding organocatalysts ((thioureas, squaramides, quinolinium thioamide, etc. in the literature containing this favored structural core. They have been successfully employed in reactions such as Friedel–Crafts alkylation, Michael addition, Diels–Alder and aza-Henry reactions. However, the 1,2-aminoindanol core incorporated into proline derivatives has been scarcely explored. Herein, the most representative and illustrative examples are compiled and this review will be mainly focused on the cases where the aminoindanol moiety confers bifunctionality to the organocatalysts.

SERIES: Genomic instability in cancer Balancing repair and tolerance of DNA damage caused by alkylating agents

OpenAIRE

Fu, Dragony; Calvo, Jennifer A.; Samson, Leona D

2012-01-01

Alkylating agents comprise a major class of frontline chemotherapeutic drugs that inflict cytotoxic DNA damage as their main mode of action, in addition to collateral mutagenic damage. Numerous cellular pathways, including direct DNA damage reversal, base excision repair (BER), and mismatch repair (MMR) respond to alkylation damage to defend against alkylation-induced cell death or mutation. However, maintaining a proper balance of activity both within and between these pathways is crucial fo...

Sensitization of human carcinoma cells to alkylating agents by small interfering RNA suppression of 3-alkyladenine-DNA glycosylase.

Science.gov (United States)

Paik, Johanna; Duncan, Tod; Lindahl, Tomas; Sedgwick, Barbara

2005-11-15

One of the major cytotoxic lesions generated by alkylating agents is DNA 3-alkyladenine, which can be excised by 3-alkyladenine DNA glycosylase (AAG). Inhibition of AAG may therefore result in increased cellular sensitivity to chemotherapeutic alkylating agents. To investigate this possibility, we have examined the role of AAG in protecting human tumor cells against such agents. Plasmids that express small interfering RNAs targeted to two different regions of AAG mRNA were transfected into HeLa cervical carcinoma cells and A2780-SCA ovarian carcinoma cells. Stable derivatives of both cell types with low AAG protein levels were sensitized to alkylating agents. Two HeLa cell lines with AAG protein levels reduced by at least 80% to 90% displayed a 5- to 10-fold increase in sensitivity to methyl methanesulfonate, N-methyl-N-nitrosourea, and the chemotherapeutic drugs temozolomide and 1,3-bis(2-chloroethyl)-1-nitrosourea. These cells showed no increase in sensitivity to UV light or ionizing radiation. After treatment with methyl methanesulfonate, AAG knockdown HeLa cells were delayed in S phase but accumulated in G2-M. Our data support the hypothesis that ablation of AAG activity in human tumor cells may provide a useful strategy to enhance the efficacy of current chemotherapeutic regimens that include alkylating agents.

Population pharmacokinetic (PK) analysis of laromustine, an emerging alkylating agent, in cancer patients.

Science.gov (United States)

Nassar, Ala F; Wisnewski, Adam V; King, Ivan

2017-05-01

1. Alkylating agents are capable of introducing an alkyl group into nucleophilic sites on DNA or RNA through covalent bond. Laromustine is an active member of a relatively new class of sulfonylhydrazine prodrugs under development as antineoplastic alkylating agents, and displays significant single-agent activity. 2. This is the first report of the population pharmacokinetic analysis of laromustine, 106 patients, 66 with hematologic malignancies and 40 with solid tumors, participated in five clinical trials worldwide. Of these, 104 patients were included in the final NONMEM analysis. 3. The population estimates for total clearance (CL) and volume of distribution of the central compartment (V 1 ) were 96.3 L/h and 45.9 L, associated with high inter-patient variability of 52.9% and 79.8% and inter-occasion variability of 26.7% and 49.3%, respectively. The population estimates for Q and V 2 were 73.2 L/h and 29.9 L, and inter-patient variability in V 2 was 63.1%, respectively. 4. The estimate of V ss (75.8 L) exceeds total body water, indicating that laromustine is distributed to tissues. The half-life is short, less than 1 h, reflecting rapid clearance. Population PK analysis showed laromustine pharmacokinetics to be independent of dose and organ function with no effect on subsequent dosing cycles.

Long Alkyl Chain Organophosphorus Coupling Agents for in Situ Surface Functionalization by Reactive Milling

Directory of Open Access Journals (Sweden)

Annika Betke

2014-08-01

Full Text Available Innovative synthetic approaches should be simple and environmentally friendly. Here, we present the surface modification of inorganic submicrometer particles with long alkyl chain organophosphorus coupling agents without the need of a solvent, which makes the technique environmentally friendly. In addition, it is of great benefit to realize two goals in one step: size reduction and, simultaneously, surface functionalization. A top-down approach for the synthesis of metal oxide particles with in situ surface functionalization is used to modify titania with long alkyl chain organophosphorus coupling agents. A high energy planetary ball mill was used to perform reactive milling using titania as inorganic pigment and long alkyl chain organophosphorus coupling agents like dodecyl and octadecyl phosphonic acid. The final products were characterized by IR, NMR and X-ray fluorescence spectroscopy, thermal and elemental analysis as well as by X-ray powder diffraction and scanning electron microscopy. The process entailed a tribochemical phase transformation from the starting material anatase to a high-pressure modification of titania and the thermodynamically more stable rutile depending on the process parameters. Furthermore, the particles show sizes between 100 nm and 300 nm and a degree of surface coverage up to 0.8 mmol phosphonate per gram.

Comparison of alkylating agent and radiation carcinogenesis: some aspects of the possible involvement of effects on DNA

International Nuclear Information System (INIS)

Lawley, P.D.

1976-01-01

A series of alkylating agents was classified in terms of increasing relative ability to react at O-atom sites in DNA, MMS 6 -alkylguanines are directly miscoding bases. This series of agents was also used in a study of comparative carcinogenicity with respect to induction of thymic lymphoma in mice, a system in which x-irradiation yields tumors. A positive correlation between ability of agents to alkylate O-6 of guanine in DNA of thymus and carcinogenic potency was found. Although MMS was not active in this system, it was noted that it can induce tumors in other systems. The relationship between repair of alkylation and radiation induced damage in DNA was briefly discussed. The methylating agents induce single-strand breaks in DNA, and the principal repair system appears to fall into the category of short repair as denoted by Regan and Setlow (1974). These single-strand breaks may result from spontaneous hydrolytic depurinations of 3- and 7-methylpurines, or from enzymatic depurinations, e.g., of 3-alkyladenine and O 6 -alkylguanine. Aralkylating agents, which are also carcinogens, can evoke an alternative repair response of the uvr type

Kinetic studies of 2-(2'-Haloethyl) and 2-ethenyl substituted quinazolinone alkylating agents. Acid-catalyzed dehydrohalogenation and alkylation involving a quinazolinone prototropic tautomer.

Science.gov (United States)

Dempcy, R O; Skibo, E B

1993-07-01

The mechanism of halide elimination from 2-haloethyl-5,8-dihydroxyquinazolin-4(3H)-ones was studied in aqueous buffer by means of a pH-rate profile, buffer dilution studies, isotopic labeling, and kinetic isotope effects. From the results of these studies, it is apparent that a quinazolinone tautomer, arising from a prototropic shift of the C(l') proton to the N(1) position, is formed in the rate determining step of elimination. Monobasic phosphate acts as a bifunctional catalyst for the tautomerism. The halide then eliminates from the tautomer to afford the alkene derivative. Conversely, hydroxyethyl mercaptide adds to the alkene to afford the tautomer. The significance of these studies lies in the discovery of a prototropic tautomer of quinazolinone, which is reversibly formed in aqueous buffer under mild conditions, and in the discovery of alkylation chemistry useful in the design of quinazolinone-based enzyme inhibitors.

Nearest neighbor affects G:C to A:T transitions induced by alkylating agents.

Science.gov (United States)

Glickman, B W; Horsfall, M J; Gordon, A J; Burns, P A

1987-01-01

The influence of local DNA sequence on the distribution of G:C to A:T transitions induced in the lacI gene of E. coli by a series of alkylating agents has been analyzed. In the case of nitrosoguanidine, two nitrosoureas and a nitrosamine, a strong preference for mutation at sites proceeded 5' by a purine base was noted. This preference was observed with both methyl and ethyl donors where the predicted common ultimate alkylating species is the alkyl diazonium ion. In contrast, this preference was not seen following treatment with ethylmethanesulfonate. The observed preference for 5'PuG-3' site over 5'-PyG-3' sites corresponds well with alterations observed in the Ha-ras oncogene recovered after treatment with NMU. This indicates that the mutations recovered in the oncogenes are likely the direct consequence of the alkylation treatment and that the local sequence effects seen in E. coli also appear to occur in mammalian cells. PMID:3329097

Nearest neighbor affects G:C to A:T transitions induced by alkylating agents

Energy Technology Data Exchange (ETDEWEB)

Glickman, B.W.; Horsfall, M.J.; Gordon, A.J.E.; Burns, P.A.

1987-12-01

The influence of local DNA sequence on the distribution of G:C to A:T transitions induced in the lacI gene of E. coli by a series of alkylating agents has been analyzed. In the case of nitrosoguanidine, two nitrosoureas and a nitrosamine, a strong preference for mutation at sites proceeded 5' by a purine base was noted. This preferences was observed with both methyl and ethyl donors where the predicted common ultimate alkylating species in the alkyl diazonium ion. In contrast, this preferences was not seen following treatment with ethylmethanesulfonate. The observed preference for 5'PuG-3' site over 5'-PyG-3' sites corresponds well with alterations observed in the Ha-ras oncogene recovered after treatment with NMU. This indicates that the mutations recovered in the oncogenes are likely the direct consequence of the alkylation treatment and that the local sequence effects seen in E. coli also appear to occur in mammalian cells.

Research on DNA methylation of human osteosarcoma cell MGMT and its relationship with cell resistance to alkylating agents.

Science.gov (United States)

Guo, Jun; Cui, Qiu; Jiang, WeiHao; Liu, Cheng; Li, DingFeng; Zeng, Yanjun

2013-08-01

The objective of this study was to explore the O(6)-methylguanine-DNA methyltransferase (MGMT) gene methylation status and its protein expression, as well as the effects of demethylating agent 5-Aza-2'-deoxycytidine (5-Aza-CdR) on MGMT gene expression and its resistance to alkylating agents, and to elucidate MGMT expression mechanism and significance in osteosarcoma. The human osteosarcoma cell lines Saos-2 and MG-63 were collected and treated with 5-Aza-CdR for 6 days. The cells not treated with 5-Aza-CdR were set as a negative control. The genomic DNA was extracted from the Saos-2 and MG-63 cells using methylation-specific PCR to detect the promoter CpG island methylation status of the MGMT gene. Cell sensitivity to alkylating agents before and after drug administration was detected by the MTT method. The variation in MGMT gene mRNA and protein was detected by reverse transcription PCR (RT-PCR) and Western blotting. The MGMT promoter gene of normal Saos-2 cells was methylated, with reduced MGMT mRNA and protein expression; the MGMT mRNA and protein expression of Saos-2 cells treated with 5-Aza-CdR was obviously enhanced, and its sensitivity to alkylating agents was reversed. Meanwhile, with promoter CpG island unmethylation of the MGMT gene, MGMT protein was expressed in the normal MG-63 cells and the MG-63 cells treated with 5-Aza-CdR, and both showed resistance to alkylating agents. The methylation status of the MGMT gene promoter in human osteosarcoma cells reflected the cells' ability to induce MGMT protein expression and can be used as a molecular marker to project the sensitivity of cancer tissues to alkylating agent drugs.

Inactivation of the DNA-repair gene MGMT and the clinical response of gliomas to alkylating agents.

Science.gov (United States)

Esteller, M; Garcia-Foncillas, J; Andion, E; Goodman, S N; Hidalgo, O F; Vanaclocha, V; Baylin, S B; Herman, J G

2000-11-09

The DNA-repair enzyme O6-methylguanine-DNA methyltransferase (MGMT) inhibits the killing of tumor cells by alkylating agents. MGMT activity is controlled by a promoter; methylation of the promoter silences the gene in cancer, and the cells no longer produce MGMT. We examined gliomas to determine whether methylation of the MGMT promoter is related to the responsiveness of the tumor to alkylating agents. We analyzed the MGMT promoter in tumor DNA by a methylation-specific polymerase-chain-reaction assay. The gliomas were obtained from patients who had been treated with carmustine (1,3-bis(2-chloroethyl)-1-nitrosourea, or BCNU). The molecular data were correlated with the clinical outcome. The MGMT promoter was methylated in gliomas from 19 of 47 patients (40 percent). This finding was associated with regression of the tumor and prolonged overall and disease-free survival. It was an independent and stronger prognostic factor than age, stage, tumor grade, or performance status. Methylation of the MGMT promoter in gliomas is a useful predictor of the responsiveness of the tumors to alkylating agents.

Antimitotic antitumor agents: synthesis, structure-activity relationships, and biological characterization of N-aryl-N'-(2-chloroethyl)ureas as new selective alkylating agents.

Science.gov (United States)

Mounetou, E; Legault, J; Lacroix, J; C-Gaudreault, R

2001-03-01

A series of N-aryl-N'-(2-chloroethyl)ureas (CEUs) and derivatives were synthesized and evaluated for antiproliferative activity against a wide panel of tumor cell lines. Systematic structure--activity relationship (SAR) studies indicated that: (i) a branched alkyl chain or a halogen at the 4-position of the phenyl ring or a fluorenyl/indanyl group, (ii) an exocyclic urea function, and (iii) a N'-2-chloroethyl moiety were required to ensure significant cytotoxicity. Biological experiments, such as immunofluorescence microscopy, confirmed that these promising compounds alter the cytoskeleton by inducing microtubule depolymerization via selective alkylation of beta-tubulin. Subsequent evaluations demonstrated that potent CEUs were weak alkylators, were non-DNA-damaging agents, and did not interact with the thiol function of either glutathione or glutathione reductase. Therefore, CEUs are part of a new class of antimitotic agents. Finally, among the series of CEUs evaluated, compounds 12, 15, 16, and 27 were selected for further in vivo trials.

Mutagenesis by alkylating agents: coding properties for DNA polymerase of poly (dC) template containing 3-methylcytosine

Energy Technology Data Exchange (ETDEWEB)

Boiteux, S.; Laval, J. (Institut Gustave-Roussy, 94 - Villejuif (France))

After treatment of poly(dC) by the simple alkylating agent (/sup 3/H)dimethylsulfate, 90 percent of the radioactivity cochromatographed with 3-methylcytosine and 10 percent with 5-methylcytosine which is the normally occurring methylated base. In order to study the influence of 3-methylcytosine on DNA replication, untreated and MDS-treated poly(dC) were used as templates for E. coli DNA polymerase I. The alkylation of poly(dC) inhibits DNA chain elongation, and does not induce any mispairing under high fidelity conditions. The alteration of DNA polymerase I fidelity by manganese ions allows some replication of 3-methylcytosine which mispairs with either dAMP or dTMP. Our results suggest that 3-methylcytosine could be responsible, at least partially, for killing and the mutagenesis observed after cell treatment by alkylating agents.

Decreased stability of DNA in cells treated with alkylating agents

Energy Technology Data Exchange (ETDEWEB)

Frankfurt, O.S. (Cedars Medical Center, Miami, FL (United States))

1990-12-01

A modified highly sensitive procedure for the evaluation of DNA damage in individual cells treated with alkylating agents is reported. The new methodology is based on the amplification of single-strandedness in alkylated DNA by heating in the presence of Mg{sup 2+}. Human ovarian carcinoma cells A2780 were treated with nitrogen mustard (HN2), fixed in methanol, and stained with monoclonal antibody (MOAB) F7-26 generated against HN2-treated DNA. Binding of MOAB was measured by flow cytometry with indirect immunofluorescence. Intensive binding of MOAB to control and drug-treated cells was observed after heating in Tris buffer supplemented with MgCl{sub 2}. Thus, the presence of phosphates and MgCl{sub 2} during heating was necessary for the detection of HN2-induced changes in DNA stability. Fluorescence of HN2-treated cells decreased to background levels after treatment with single-strand-specific S{sub 1} nuclease. MOAB F7-26 interacted with single-stranded regions in DNA and did not bind to dsDNA or other cellular antigens. It is suggested that alkylation of guanines decreased the stability of the DNA molecule and increased the access of MOAB F7-26 to deoxycytidines on the opposite DNA strand.

Alkylation of enolate anions formation of enol ethers

NARCIS (Netherlands)

Heiszwolf, G.J.; Kloosterziel, H.

1970-01-01

The alkylation of ambident enolate anions-obtained from aliphatic ketones (and one particular type of aldehyde)-was studied using various solvents, bases, alkylating agents and substrates. Alkylation with a reactive alkylating agent (dialkyl sulfates, triethyloxonium fluoroborate) in an aprotic

Comparison of the oncogenic potential of several chemotherapeutic agents

International Nuclear Information System (INIS)

Miller, R.C.; Hall, E.J.; Osmak, R.S.

1981-01-01

Several chemotherapeutic drugs that have been routinely used in cancer treatment were tested for their carcinogenic potential. Two antitumor antibiotics (adriamycin and vincristine), an alkalating agent (melphalan), 5-azacytidine and the bifunctional agent cis-platinum that mimics alkylating agents and/or binds Oxygen-6 or Nitrogen-7 atoms of quanine were tested. Cell killing and cancer induction was assessed using in vitro transformation system. C3H/10T 1/2 cells, while normally exhibiting contact inhibition, can undergo transformation from normal contact inhibited cells to tumorgenic cells when exposed to chemical carcinogens. These cells have been used in the past by this laboratory to study oncogenic transformation of cells exposed to ionizing radiation and electron affinic compounds that sensitize hypoxic cells to x-rays. The endpoints of cell killing and oncogenic transformation presented here give an estimate of the carcinogenic potential of these agents

Cellular response to alkylating agent MNNG is impaired in STAT1-deficients cells.

Science.gov (United States)

Ah-Koon, Laurent; Lesage, Denis; Lemadre, Elodie; Souissi, Inès; Fagard, Remi; Varin-Blank, Nadine; Fabre, Emmanuelle E; Schischmanoff, Olivier

2016-10-01

The SN 1 alkylating agents activate the mismatch repair system leading to delayed G2 /M cell cycle arrest and DNA repair with subsequent survival or cell death. STAT1, an anti-proliferative and pro-apoptotic transcription factor is known to potentiate p53 and to affect DNA-damage cellular response. We studied whether STAT1 may modulate cell fate following activation of the mismatch repair system upon exposure to the alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Using STAT1-proficient or -deficient cell lines, we found that STAT1 is required for: (i) reduction in the extent of DNA lesions, (ii) rapid phosphorylation of T68-CHK2 and of S15-p53, (iii) progression through the G2 /M checkpoint and (iv) long-term survival following treatment with MNNG. Presence of STAT1 is critical for the formation of a p53-DNA complex comprising: STAT1, c-Abl and MLH1 following exposure to MNNG. Importantly, presence of STAT1 allows recruitment of c-Abl to p53-DNA complex and links c-Abl tyrosine kinase activity to MNNG-toxicity. Thus, our data highlight the important modulatory role of STAT1 in the signalling pathway activated by the mismatch repair system. This ability of STAT1 to favour resistance to MNNG indicates the targeting of STAT1 pathway as a therapeutic option for enhancing the efficacy of SN1 alkylating agent-based chemotherapy. © 2016 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Regular character of chromatin degradation in lymphoid tissues after treatment with biological alkylating agents in vivo

International Nuclear Information System (INIS)

Matyasova, J.; Skalka, M.; Cejkova, M.

1979-01-01

The chromatin changes are reevaluated occurring in lymphoid tissues of mice treated with alkylating agents of the nitrogen-mustard type in relation to recent evidence on the nucleosomal organization of chromatin and to our new data on the regular character of chromatin degradation in lymphoid tissues of irradiated mice. DNA was isolated from nuclei at various intervals (1 to 18 h) after treatment of mice and subjected to gel electrophoresis in polyacrylamide gels. Thymus chromatin from treated mice has been shown to degrade in a regular fashion and to yield discrete DNA fragments, resembling those that originate in lymphoid tissues of irradiated mice or in thymus nuclei digested with micrococcal nuclease in vitro. With increasing interval after treatment higher amounts of smaller DNA fragments appear. Chromatin in spleen cells responds to treatment in a similar way, whilst no degradation in vivo takes place in liver chromatin. Chromatin of LS/BL lymphosarcoma cells in mice treated with alkylating agents or with irradiation suffers from a similar regular degradation. The results stress the significance of the action of liberated or activated endogenous nuclease(s) in the development of chromatin damage in lymphoid cells after treatment with alkylating agents. (author)

Risk of therapy-related leukaemia and preleukaemia after Hodgkin's disease. Relation to age, cumulative dose of alkylating agents, and time from chemotherapy

DEFF Research Database (Denmark)

Pedersen-Bjergaard, J.; Specht, L.; Larsen, S.O.

1987-01-01

391 patients treated intensively for Hodgkin's disease were followed for up to 15 years to evaluate the risk of therapy-related acute non-lymphocytic leukaemia (t-ANLL) and preleukaemia. Only two independent factors, patient age and cumulative dose of alkylating agents, were related to the risk...... of t-ANLL. The hazard rate of t-ANLL was roughly proportional to the square of patient age and to the total cumulative dose of alkylating agents. In 320 patients treated with alkylating agents the cumulative risk of t-ANLL increased steadily from 1 year after the start of treatment and reached 13.......0% (SE 3.0) at 10 years after which time there were no further cases. Calculated from cessation of therapy with alkylating agents, however, the cumulative risk curve increased steeply during the first 1-2 years then gradually levelled out and no new cases were observed beyond 7 years. With a 15-year...

L-β-N-methylamino-l-alanine (BMAA) nitrosation generates a cytotoxic DNA damaging alkylating agent: An unexplored mechanism for neurodegenerative disease.

Science.gov (United States)

Potjewyd, G; Day, P J; Shangula, S; Margison, G P; Povey, A C

2017-03-01

L-β-N-methylamino-l-alanine (BMAA) is a non-proteinic amino acid, that is neurotoxic in vitro and in animals, and is implicated in the causation of amyotrophic lateral sclerosis and parkinsonism-dementia complex (ALS-PDC) on Guam. Given that natural amino acids can be N-nitrosated to form toxic alkylating agents and the structural similarity of BMAA to other amino acids, our hypothesis was that N-nitrosation of BMAA might result in a toxic alkylating agent, providing a novel mechanistic hypothesis for BMAA action. We have chemically nitrosated BMAA with sodium nitrite to produce nitrosated BMAA (N-BMAA) which was shown to react with the alkyl-trapping agent, 4-(p-nitrobenzyl)pyridine, cause DNA strand breaks in vitro and was toxic to the human neuroblastoma cell line SH-SY5Y under conditions in which BMAA itself was minimally toxic. Our results indicate that N-BMAA is an alkylating agent and toxin suggesting a plausible and previously unrecognised mechanism for the neurotoxic effects of BMAA. Copyright © 2017 Elsevier B.V. All rights reserved.

Formation of enamines by alkylation of imines

NARCIS (Netherlands)

Heiszwolf, G.J.; Kloosterziel, H.

1966-01-01

cf. CA 64, 12473c. With ice-cooling, 1 equiv. alkylating agent was added to one equiv. of the imine in 1M soln. in a solvent in the presence of NaH to give both N- and C-alkylated products. The following summarizes the date (imine, solvent, alkylating agent, % unreacted imine, % N-alkylated product,

Iminium ion chemistry of mitosene DNA alkylating agents. Enriched 13C NMR and isolation studies.

Science.gov (United States)

Ouyang, A; Skibo, E B

2000-05-16

Described herein is a study of the reductive alkylation chemistry of mitosene antitumor agents. We employed a 13C-enriched electrophilic center to probe the fate of the iminium ion resulting from reductive activation. The 13C-labeled center permitted the identification of complex products resulting from alkylation reactions. In the case of DNA reductive alkylation, the type and number of alkylation sites were readily assessed by 13C NMR. Although there has been much excellent work done in the area of mitosene chemistry and biochemistry, the present study provides a number of new findings: (1) The major fate of the iminium ion is head-to-tail polymerization, even in dilute solutions. (2) Dithionite reductive activation results in the formation of mitosene sulfite esters as well as the previously observed sulfonate adducts. (3) The mitosene iminium ion alkylates the adenosine 6-amino group as well as the guanosine 2-amino group. The identification of the latter adduct was greatly facilitated by the 13C-label at the electrophilic center. (4) The mitosene iminium ion alkylates DNA at both nitrogen and oxygen centers without any apparent base selectivity. The complexity of mitosene reductive alkylation of DNA will require continued adduct isolation studies.

Direct-acting DNA alkylating agents present in aqueous extracts of areca nut and its products.

Science.gov (United States)

Hu, Chiung-Wen; Chao, Mu-Rong

2012-11-19

Areca nut is a carcinogen to humans and has been strongly associated with oral premalignant and malignant diseases. Previous studies speculated the presence of unknown direct-acting mutagens present in aqueous extracts of areca nut. We hypothesized whether any direct-acting alkylating agents are present in areca nut and its commercial products. In this study, calf thymus DNA was treated with four different aqueous extracts obtained from unripe and ripe areca nuts or their commercial products, namely, pan masala (without tobacco) and gutkha (with tobacco). Three N-alkylated purines including N7-methylguanine (N7-MeG), N3-methyladenine (N3-MeA), and N7-ethylguanine (N7-EtG) were detected using sensitive and specific isotope-dilution liquid chromatography-tandem-mass spectrometry (LC-MS/MS) methods. The results showed that four types of aqueous extracts significantly induced the formation of N7-MeG and N3-MeA in a linear dose-response manner. Extracts from unripe areca nut exhibited higher methylating potency than those of ripe areca nut, while gutkha had higher methylating potency than pan masala. Meanwhile, gutkha made with areca nut and tobacco, was the only extract found to induce the formation of N7-EtG. Overall, this study first demonstrated that the presence of direct-acting alkylating agents in areca nut and its commercial products exist at a level that is able to cause significant DNA damage. Our findings may provide another mechanistic rationale for areca nut-mediated oral carcinogenesis and also highlight the importance and necessity of the identification of these direct-acting alkylating agents.

Effects of Photo-chemically Activated Alkylating Agents of the FR900482 Family on Chromatin

Science.gov (United States)

Subramanian, Vidya; Ducept, Pascal; Williams, Robert M.; Luger, Karolin

2011-01-01

SUMMARY Bioreductive alkylating agents are an important class of clinical antitumor antibiotics that cross-link and mono-alkylate DNA. Here we use a synthetic photochemically activated derivative of FR400482 to investigate the molecular mechanism of this class of drugs in a biologically relevant context. We find that the organization of DNA into nucleosomes effectively protects it against drug-mediated cross-linking, while permitting mono-alkylation. This modification has the potential to form covalent cross-links between chromatin and nuclear proteins. Using in vitro approaches, we found that interstrand cross-linking of free DNA results in a significant decrease in basal and activated transcription. Finally, cross-linked plasmid DNA is inefficiently assembled into chromatin. Our studies suggest new pathways for the clinical effectiveness of this class of reagents. PMID:17524986

VP-16 and alkylating agents activate a common metabolic pathway for suppression of DNA replication

International Nuclear Information System (INIS)

Das, S.K.; Berger, N.A.

1986-01-01

The cytotoxic effects of etoposide (VP-16) are mediated by topoisomerase II production of protein crosslinked DNA strand breaks. Previous studies have shown that alkylating agent induced DNA damage results in expansion of dTTP pools and reduction of dCTP pools and DNA replication. Studies were conducted with V79 cells to determine whether the metabolic consequences of VP-16 treatment were similar to those induced by alkylating agents. Treatment with 0.5μM VP-16 prolonged the doubling time of V79 cells from 12 to 18 hrs and caused cell volume to increase from 1.1 to 1.6 x 10 -12 l. 2mM caffeine completely blocked the volume increase and substantially prevented the prolongation of doubling time. 5μM VP-16 reduced the rate of [ 3 H]TdR incorporation by 70%, whereas in the presence of 2mM caffeine, VP-16 caused only a 10% decrease in the rate of [ 3 H]TdR incorporation. 4 hr treatment with 5.0μM VP-16 increased dTTP levels from 65 +/- 10 pmol/10 6 cells to 80 +/- 13 pmol/10 6 cells and caused dCTP level to decline from 113 +/- 23 pmol/10 6 cells to 92 +/- 17 pmol/10 6 cells. These results indicate that the metabolic consequences of VP-16 treatment are similar to alkylating agent treatment and that an increase in dTTP pools with a subsequent effect on ribonucleotide reductase may be a final common pathway by which many cytotoxic agents suppress DNA synthesis

Bifunctional Agents for MRI, PET and Fluorescence Imaging and Study of Nanoparticles Formed from Water Oxidation Catalysts /

OpenAIRE

Abadjian, Marie-Caline Z.

2014-01-01

The work is divided into four parts : (1) MRI contrast agents are designed to enhance T₁ relaxivity by coupling them to dendrimers, the precise structure of which can be controlled through synthesis. Cyclen is used as a starting scaffold for the synthesis of bifunctional Gd-DOTA and Gd- DOTMA analogues. One unique side chain on the macrocycle contains an azide moiety that can be clicked to an alkyne- containing core, making a first-generation dendrimer with the potential to improve MRI effici...

O6-Methylguanine DNA Methyltransferase Status Does Not Predict Response or Resistance to Alkylating Agents in Well-Differentiated Pancreatic Neuroendocrine Tumors.

Science.gov (United States)

Raj, Nitya; Klimstra, David S; Horvat, Natally; Zhang, Liying; Chou, Joanne F; Capanu, Marinela; Basturk, Olca; Do, Richard Kinh Gian; Allen, Peter J; Reidy-Lagunes, Diane

2017-07-01

Alkylating agents have activity in well-differentiated pancreatic neuroendocrine tumors (WD panNETs). In glioblastoma multiforme, decreased activity of O-methylguanine DNA methyltransferase (MGMT) predicts response; in panNETs, MGMT relevance is unknown. We identified patients with WD panNETs treated with alkylating agents, determined best overall response by Response Evaluation Criteria In Solid Tumors (RECIST) 1.1, and performed MGMT activity testing. Fifty-six patients were identified; 26 (46%) of the 56 patients experienced partial response, 24 (43%) of 56 experienced stable disease, and 6 (11%) of 56 experienced progression of disease. O-methylguanine DNA methyltransferase status was available for 36 tumors. For tumors with partial response, 10 (67%) of 15 were MGMT deficient, and 5 (33%) of 15 were MGMT intact. For tumors with stable disease, 7 (47%) of 15 were MGMT deficient, and 8 (53%) of 15 were MGMT intact. For tumors with progression of disease, 3 (50%) of 6 were MGMT deficient, and 3 (50%) of 6 were MGMT intact. We observed response and resistance to alkylating agents in MGMT-deficient and MGMT-intact tumors. O-methylguanine DNA methyltransferase status should not guide alkylating agent therapy in WD panNETs.

Current approaches to improve the anticancer chemotherapy with alkylating agents: state of the problem in world and Ukraine.

Directory of Open Access Journals (Sweden)

Iatsyshyna A. P.

2012-01-01

Full Text Available Alkylating agents are frequently used in many established anticancer chemotherapies. They alkylate the genomic DNA at various sites. Alkylation of the guanine at the O6-position is cytotoxic, it has the strongest mutagenic potential, as well as can cause the tumor development. Alkyl groups at the O6-position of guanine are removed by the DNA repair enzyme O6-methylguanine-DNA methyltransferase (MGMT. The effectiveness of alkylating chemotherapy is limited by MGMT in cancer cells and adverse toxic side effects in normal cells. Different approaches consisting in the modulation of the MGMT expression and activity are under development now to improve the cancer chemotherapy. They include two main directions, in particular, the increase in chemosensitivity of cancer cells to alkylating drugs and the protection of normal cells from the toxic side effects of chemotherapy. This review is focused on current attempts to improve the alkylating chemotherapy of malignant tumours worldwide and state of the issue in Ukraine

Alkylating Agent-Induced NRF2 Blocks Endoplasmic Reticulum Stress-Mediated Apoptosis via Control of Glutathione Pools and Protein Thiol Homeostasis.

Science.gov (United States)

Zanotto-Filho, Alfeu; Masamsetti, V Pragathi; Loranc, Eva; Tonapi, Sonal S; Gorthi, Aparna; Bernard, Xavier; Gonçalves, Rosângela Mayer; Moreira, José C F; Chen, Yidong; Bishop, Alexander J R

2016-12-01

Alkylating agents are a commonly used cytotoxic class of anticancer drugs. Understanding the mechanisms whereby cells respond to these drugs is key to identify means to improve therapy while reducing toxicity. By integrating genome-wide gene expression profiling, protein analysis, and functional cell validation, we herein demonstrated a direct relationship between NRF2 and Endoplasmic Reticulum (ER) stress pathways in response to alkylating agents, which is coordinated by the availability of glutathione (GSH) pools. GSH is essential for both drug detoxification and protein thiol homeostasis within the ER, thus inhibiting ER stress induction and promoting survival, an effect independent of its antioxidant role. NRF2 accumulation induced by alkylating agents resulted in increased GSH synthesis via GCLC/GCLM enzyme, and interfering with this NRF2 response by either NRF2 knockdown or GCLC/GCLM inhibition with buthionine sulfoximine caused accumulation of damaged proteins within the ER, leading to PERK-dependent apoptosis. Conversely, upregulation of NRF2, through KEAP1 depletion or NRF2-myc overexpression, or increasing GSH levels with N-acetylcysteine or glutathione-ethyl-ester, decreased ER stress and abrogated alkylating agents-induced cell death. Based on these results, we identified a subset of lung and head-and-neck carcinomas with mutations in either KEAP1 or NRF2/NFE2L2 genes that correlate with NRF2 target overexpression and poor survival. In KEAP1-mutant cancer cells, NRF2 knockdown and GSH depletion increased cell sensitivity via ER stress induction in a mechanism specific to alkylating drugs. Overall, we show that the NRF2-GSH influence on ER homeostasis implicates defects in NRF2-GSH or ER stress machineries as affecting alkylating therapy toxicity. Mol Cancer Ther; 15(12); 3000-14. ©2016 AACR. ©2016 American Association for Cancer Research.

Alkylating agent induced NRF2 blocks endoplasmic reticulum stress-mediated apoptosis via control of glutathione pools and protein thiol homeostasis

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Zanotto-Filho, Alfeu; Masamsetti, V. Pragathi; Loranc, Eva; Tonapi, Sonal S.; Gorthi, Aparna; Bernard, Xavier; Gonçalves, Rosângela Mayer; Moreira, José C. F.; Chen, Yidong; Bishop, Alexander J. R.

2016-01-01

Alkylating agents are a commonly used cytotoxic class of anticancer drugs. Understanding the mechanisms whereby cells respond to these drugs is key to identify means to improve therapy while reducing toxicity. By integrating genome-wide gene expression profiling, protein analysis and functional cell validation, we herein demonstrated a direct relationship between NRF2 and Endoplasmic Reticulum (ER) stress pathways in response to alkylating agents, which is coordinated by the availability of glutathione (GSH) pools. GSH is essential for both drug detoxification and protein thiol homeostasis within the ER, thus inhibiting ER stress induction and promoting survival; an effect independent of its antioxidant role. NRF2 accumulation induced by alkylating agents resulted in increased GSH synthesis via GCLC/GCLM enzyme, and interfering with this NRF2 response by either NRF2 knockdown or GCLC/GCLM inhibition with buthionine sulfoximine (BSO) caused accumulation of damaged proteins within the ER, leading to PERK-dependent apoptosis. Conversely, upregulation of NRF2, through KEAP1 depletion or NRF2-myc overexpression, or increasing GSH levels with N-acetylcysteine (NAC) or glutathione-ethyl-ester (GSH-E), decreased ER stress and abrogated alkylating agents-induced cell death. Based on these results, we identified a subset of lung and head-and-neck carcinomas with mutations in either KEAP1 or NRF2/NFE2L2 genes that correlate with NRF2 targets overexpression and poor survival. In KEAP1 mutant cancer cells, NRF2 knockdown and GSH depletion increased cell sensitivity via ER stress induction in a mechanism specific to alkylating drugs. Overall, we show that the NRF2-GSH influence on ER homeostasis implicates defects in NRF2-GSH or ER stress machineries as affecting alkylating therapy toxicity. PMID:27638861

Glutamine deficiency induces DNA alkylation damage and sensitizes cancer cells to alkylating agents through inhibition of ALKBH enzymes.

Directory of Open Access Journals (Sweden)

Thai Q Tran

2017-11-01

Full Text Available Driven by oncogenic signaling, glutamine addiction exhibited by cancer cells often leads to severe glutamine depletion in solid tumors. Despite this nutritional environment that tumor cells often experience, the effect of glutamine deficiency on cellular responses to DNA damage and chemotherapeutic treatment remains unclear. Here, we show that glutamine deficiency, through the reduction of alpha-ketoglutarate, inhibits the AlkB homolog (ALKBH enzymes activity and induces DNA alkylation damage. As a result, glutamine deprivation or glutaminase inhibitor treatment triggers DNA damage accumulation independent of cell death. In addition, low glutamine-induced DNA damage is abolished in ALKBH deficient cells. Importantly, we show that glutaminase inhibitors, 6-Diazo-5-oxo-L-norleucine (DON or CB-839, hypersensitize cancer cells to alkylating agents both in vitro and in vivo. Together, the crosstalk between glutamine metabolism and the DNA repair pathway identified in this study highlights a potential role of metabolic stress in genomic instability and therapeutic response in cancer.

Glutamine deficiency induces DNA alkylation damage and sensitizes cancer cells to alkylating agents through inhibition of ALKBH enzymes.

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Tran, Thai Q; Ishak Gabra, Mari B; Lowman, Xazmin H; Yang, Ying; Reid, Michael A; Pan, Min; O'Connor, Timothy R; Kong, Mei

2017-11-01

Driven by oncogenic signaling, glutamine addiction exhibited by cancer cells often leads to severe glutamine depletion in solid tumors. Despite this nutritional environment that tumor cells often experience, the effect of glutamine deficiency on cellular responses to DNA damage and chemotherapeutic treatment remains unclear. Here, we show that glutamine deficiency, through the reduction of alpha-ketoglutarate, inhibits the AlkB homolog (ALKBH) enzymes activity and induces DNA alkylation damage. As a result, glutamine deprivation or glutaminase inhibitor treatment triggers DNA damage accumulation independent of cell death. In addition, low glutamine-induced DNA damage is abolished in ALKBH deficient cells. Importantly, we show that glutaminase inhibitors, 6-Diazo-5-oxo-L-norleucine (DON) or CB-839, hypersensitize cancer cells to alkylating agents both in vitro and in vivo. Together, the crosstalk between glutamine metabolism and the DNA repair pathway identified in this study highlights a potential role of metabolic stress in genomic instability and therapeutic response in cancer.

Evaluation of fluorine-18-labeled alkylating agents as potential synthons for the labeling of oligonucleotides

NARCIS (Netherlands)

de Vries, EFJ; Vroegh, J; Elsinga, PH; Vaalburg, W

Six fluorine-18-labeled alkylating agents were selected as potentially suitable synthons for the labeling of antisense oligonucleotides. The selected synthons were evaluated in a model reaction with the monomer adenosine 5'-O-thiomonophosphate. Of these synthons,

Effective chemotherapy of acute myelocytic leukemia occurring after alkylating agent or radiation therapy for prior malignancy

International Nuclear Information System (INIS)

Vaughan, W.P.; Karp, J.E.; Burke, P.J.

1983-01-01

Eleven consecutive patients with acute myelocytic leukemia occurring as a second malignancy were treated with high-dose, timed, sequential chemotherapy. Eight of the patients were felt to have ''secondary'' acute leukemia because they had received an alkylating agent or radiation therapy. The other three patients were considered controls. Despite a median age of 65, four of the eight secondary leukemia patients achieved complete remission with this regimen. One of the three control patients also achieved complete remission. This remission rate and duration are comparable to what was achieved with this treatment of ''primary'' acute myelocytic leukemia during the same period of time. These results suggest that patients with leukemia occurring after an alkylating agent or radiation therapy are not at especially high risk if treated aggressively

Activation of the chemosensing transient receptor potential channel A1 (TRPA1) by alkylating agents.

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Stenger, Bernhard; Zehfuss, Franziska; Mückter, Harald; Schmidt, Annette; Balszuweit, Frank; Schäfer, Eva; Büch, Thomas; Gudermann, Thomas; Thiermann, Horst; Steinritz, Dirk

2015-09-01

The transient receptor potential ankyrin 1 (TRPA1) cation channel is expressed in different tissues including skin, lung and neuronal tissue. Recent reports identified TRPA1 as a sensor for noxious substances, implicating a functional role in the molecular toxicology. TRPA1 is activated by various potentially harmful electrophilic substances. The chemical warfare agent sulfur mustard (SM) is a highly reactive alkylating agent that binds to numerous biological targets. Although SM is known for almost 200 years, detailed knowledge about the pathophysiology resulting from exposure is lacking. A specific therapy is not available. In this study, we investigated whether the alkylating agent 2-chloroethyl-ethylsulfide (CEES, a model substance for SM-promoted effects) and SM are able to activate TRPA1 channels. CEES induced a marked increase in the intracellular calcium concentration ([Ca(2+)]i) in TRPA1-expressing but not in TRPA1-negative cells. The TRP-channel blocker AP18 diminished the CEES-induced calcium influx. HEK293 cells permanently expressing TRPA1 were more sensitive toward cytotoxic effects of CEES compared with wild-type cells. At low CEES concentrations, CEES-induced cytotoxicity was prevented by AP18. Proof-of-concept experiments using SM resulted in a pronounced increase in [Ca(2+)]i in HEK293-A1-E cells. Human A549 lung epithelial cells, which express TRPA1 endogenously, reacted with a transient calcium influx in response to CEES exposure. The CEES-dependent calcium response was diminished by AP18. In summary, our results demonstrate that alkylating agents are able to activate TRPA1. Inhibition of TRPA1 counteracted cellular toxicity and could thus represent a feasible approach to mitigate SM-induced cell damage.

DNA-directed alkylating ligands as potential antitumor agents: sequence specificity of alkylation by intercalating aniline mustards.

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Prakash, A S; Denny, W A; Gourdie, T A; Valu, K K; Woodgate, P D; Wakelin, L P

1990-10-23

The sequence preferences for alkylation of a series of novel parasubstituted aniline mustards linked to the DNA-intercalating chromophore 9-aminoacridine by an alkyl chain of variable length were studied by using procedures analogous to Maxam-Gilbert reactions. The compounds alkylate DNA at both guanine and adenine sites. For mustards linked to the acridine by a short alkyl chain through a para O- or S-link group, 5'-GT sequences are the most preferred sites at which N7-guanine alkylation occurs. For analogues with longer chain lengths, the preference of 5'-GT sequences diminishes in favor of N7-adenine alkylation at the complementary 5'-AC sequence. Magnesium ions are shown to selectively inhibit alkylation at the N7 of adenine (in the major groove) by these compounds but not the alkylation at the N3 of adenine (in the minor groove) by the antitumor antibiotic CC-1065. Effects of chromophore variation were also studied by using aniline mustards linked to quinazoline and sterically hindered tert-butyl-9-aminoacridine chromophores. The results demonstrate that in this series of DNA-directed mustards the noncovalent interactions of the carrier chromophores with DNA significantly modify the sequence selectivity of alkylation by the mustard. Relationships between the DNA alkylation patterns of these compounds and their biological activities are discussed.

Enhanced mutagenicity of low doses of alkylating agents and UV-light by inhibition of ribonucleotide reductase

International Nuclear Information System (INIS)

Jenssen, D.

1986-01-01

Monofunctional alkylating agents and UV-light are potent inducers of gene mutations in mammalian cells. Most data on these agent are supporting the idea that 0/sup 6/-alkylguanine is the dominating lesion responsible for the mutations induced by the alkylating agents and thymine-dimers in the case of UV-light. However, little is known about the mutagenic fate of these lesions during the replicative process. This is an essential issue to investigate not the least because of quantitative aspects. By investigating the factors affecting the mutagenic yield of these lesions, they hope to get further information on the mechanisms(s) involved. To study this, a system was applied which involves synchronized V79 Chinese hamster cells and inhibitors of the replication process. By applying hydroxyurea (HU), as inhibitor of the ribonucleotide reductase (RNR) step in DNA synthesis, the effect of nucleotide pool imbalance has been studied at the HGPRT-locus using V79 Chinese hamster cells

Antitumor activity of sequence-specific alkylating agents: pyrolle-imidazole CBI conjugates with indole linker.

Science.gov (United States)

Shinohara, Ken-ichi; Bando, Toshikazu; Sasaki, Shunta; Sakakibara, Yogo; Minoshima, Masafumi; Sugiyama, Hiroshi

2006-03-01

DNA-targeting agents, including cisplatin, bleomycin and mitomycin C, are used routinely in cancer treatments. However, these drugs are extremely toxic, attacking normal cells and causing severe side effects. One important question to consider in designing anticancer agents is whether the introduction of sequence selectivity to DNA-targeting agents can improve their efficacy as anticancer agents. In the present study, the growth inhibition activities of an indole-seco 1,2,9,9a-tetrahydrocyclopropa[1,2-c]benz[1,2-e]indol-4-one (CBI) (1) and five conjugates with hairpin pyrrole-imidazole polyamides (2-6), which have different sequence specificities for DNA alkylation, were compared using 10 different cell lines. The average values of -log GI50 (50% growth inhibition concentration) for compounds 1-6 against the 10 cell lines were 8.33, 8.56, 8.29, 8.04, 8.23 and 8.83, showing that all of these compounds strongly inhibit cell growth. Interestingly, each alkylating agent caused significantly different growth inhibition patterns with each cell line. In particular, the correlation coefficients between the -log GI50 of compound 1 and its conjugates 2-6 showed extremely low values (Ralkylation lead to marked differences in biological activity. Comparison of the correlation coefficients between compounds 6 and 7, with the same sequence specificity as 6, and MS-247, with sequence specificity different from 6, when used against a panel of 37 human cancer cell lines further confirmed the above hypothesis.

Quantitative assessment of the dose-response of alkylating agents in DNA repair proficient and deficient ames tester strains.

Science.gov (United States)

Tang, Leilei; Guérard, Melanie; Zeller, Andreas

2014-01-01

Mutagenic and clastogenic effects of some DNA damaging agents such as methyl methanesulfonate (MMS) and ethyl methanesulfonate (EMS) have been demonstrated to exhibit a nonlinear or even "thresholded" dose-response in vitro and in vivo. DNA repair seems to be mainly responsible for these thresholds. To this end, we assessed several mutagenic alkylators in the Ames test with four different strains of Salmonella typhimurium: the alkyl transferases proficient strain TA1535 (Ogt+/Ada+), as well as the alkyl transferases deficient strains YG7100 (Ogt+/Ada-), YG7104 (Ogt-/Ada+) and YG7108 (Ogt-/Ada-). The known genotoxins EMS, MMS, temozolomide (TMZ), ethylnitrosourea (ENU) and methylnitrosourea (MNU) were tested in as many as 22 concentration levels. Dose-response curves were statistically fitted by the PROAST benchmark dose model and the Lutz-Lutz "hockeystick" model. These dose-response curves suggest efficient DNA-repair for lesions inflicted by all agents in strain TA1535. In the absence of Ogt, Ada is predominantly repairing methylations but not ethylations. It is concluded that the capacity of alkyl-transferases to successfully repair DNA lesions up to certain dose levels contributes to genotoxicity thresholds. Copyright © 2013 Wiley Periodicals, Inc.

Frequency and spectrum of chlorophyll-deficient mutations in rice after treatment with radiation and alkylating agents

International Nuclear Information System (INIS)

Bhan, A.K.; Kaul, M.L.H.

1976-01-01

Three varieties of rice were treated with gamma rays and two alkylating agents EMS and DES, separately and in combinations, with a view to finding out the frequency and spectrum of chlorophyll mutations in relation to the genotype and the nature of the mutagen. Chlorophyll mutation frequency was enhanced with increasing dose but dropped at very high doses (doses that induced over 90% seeding lethality in M 1 ). The fall was attributed to either the increased mutated sector and diplontic selection after exposure to very high doses or relatively high resistance of some of the seeds. Among chlorophyll mutants in M 2 induced by radiations as well as alkylating agents, the albina type formed the majority class. EMS induced a significantly higher proportion of albinas than did gamma rays

[Variability of the sensitivity of human lymphocytes to the antiproliferative action of alkylating agents].

Science.gov (United States)

Veremko, L N; Telegin, L Iu; Pevnitskii, L A

1983-05-01

A study was made of variability of the sensitivity of peripheral blood lymphocytes from different donors to an antiproliferative action of cyclophosphamide and thiophosphamide. A similar degree of the sensitivity was revealed to alkylating agents differing in the action mode, with this degree being independent of the "stimulation index" magnitude.

Glutathione Depletion Induced by c-Myc Downregulation Triggers Apoptosis on Treatment with Alkylating Agents1

Science.gov (United States)

Biroccio, Annamaria; Benassi, Barbara; Fiorentino, Francesco; Zupi, Gabriella

2004-01-01

Abstract Here we investigate the mechanism(s) involved in the c-Myc-dependent drug response of melanoma cells. By using three M14-derived c-Myc low-expressing clones, we demonstrate that alkylating agents, cisplatin and melphalan, trigger apoptosis in the c-Myc antisense transfectants, but not in the parental line. On the contrary, topoisomerase inhibitors, adriamycin and camptothecin, induce apoptosis to the same extent regardless of c-Myc expression. Because we previously demonstrated that c-Myc downregulation decreases glutathione (GSH) content, we evaluated the role of GSH in the apoptosis induced by the different drugs. In control cells treated with one of the alkylating agents or the others, GSH depletion achieved by l-buthionine-sulfoximine preincubation opens the apoptotic pathway. The apoptosis proceeded through early Bax relocalization, cytochrome c release, and concomitant caspase-9 activation, whereas reactive oxygen species production and alteration of mitochondria membrane potential were late events. That GSH was determining in the c-Myc-dependent drug-induced apoptosis was demonstrated by altering the intracellular GSH content of the c-Myc low-expressing cells up to the level of controls. Indeed, GSH ethyl ester-mediated increase of GSH abrogated apoptosis induced by cisplatin and melphalan by inhibition of Bax/cytochrome c redistribution. The relationship among c-Myc, GSH content, and the response to alkylating agent has been also evaluated in the M14 Myc overexpressing clones as well as in the melanoma JR8 c-Myc antisense transfectants. All together, these results demonstrate that GSH plays a key role in governing c-Myc-dependent drug-induced apoptosis. PMID:15153331

Hypoxia-Activated Alkylating Agents in BRCA1-Mutant Ovarian Serous Carcinoma.

Science.gov (United States)

Conroy, Michael; Borad, Mitesh J; Bryce, Alan H

2017-07-26

Breast cancer 1 antigen (BRCA 1) and breast cancer 2 antigen (BRCA2) genes play a significant role in deoxyribonucleic acid (DNA) repair by means of interstrand crosslink repair, and deleterious germline mutations of these are responsible for most hereditary breast and ovarian cancers. Therapeutic strategies which specifically target interstrand crosslink repair can therefore be helpful in patients with harmful mutations. We describe two patients with advanced ovarian cancer and deleterious BRCA1 mutations who were treated with TH-302, a hypoxia-activated alkylating agent.

Quantitative and subcellular localization analysis of the nuclear isoform dUTP pyrophosphatase in alkylating agent-induced cell responses

International Nuclear Information System (INIS)

Hu, Xiaolan; Yu, Yingnian; Li, Qian; Wu, Danxiao; Tan, Zhengning; Wang, Cheng; Wang, Jvping; Wu, Meiping

2011-01-01

Highlights: → MNNG-induced appearance of DUT-N in the extracellular fluid has cellular specificity. → MNNG alters the subcellular distribution of DUT-N in human cells in different ways. → DUT-N may be a potential biomarker to assess the risk of alkylating agents exposure. -- Abstract: Our previous proteome analysis showed that the nuclear isoform of dUTP pyrophosphatase (DUT-N) was identified in the culture medium of human amnion FL cells after exposure to the alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). These results suggest that DUT-N may be a potential early biomarker to assess the risk of alkylating agents exposure. DUT-N is one of the two isoforms of deoxyuridine triphosphate nucleotidohydrolase (dUTPase). Our current knowledge of DUT-N expression in human cells is very limited. In the current study, we first investigated the appearance of DUT-N in the culture medium of different human cell lines in response to a low concentration of MNNG exposure. We verified that the MNNG-induced appearance of DUT-N in the extracellular environment is cell-specific. Western blot analysis confirmed that the intracellular DUT-N changes responded to MNNG in a concentration-dependent and cell-specific manner. Furthermore, subcellular fraction experiments showed that 0.25 μM MNNG treatment dramatically increased the DUT-N expression levels in the cytoplasmic extracts prepared from both FL and HepG2 cells, increased DUT-N levels in nuclear extracts prepared from HepG2 cells, and decreased DUT-N levels in nuclear extracts from FL cells. Morphological studies using immunofluorescence showed that a low concentration of MNNG could alter the distribution of DUT-N in FL and HepG2 cells in different ways. Taken together, these studies indicate a role of DUT-N in alkylating agent-induced cell responses.

Female cancer survivors exposed to alkylating-agent chemotherapy have unique reproductive hormone profiles.

Science.gov (United States)

Johnson, Lauren; Sammel, Mary D; Schanne, Allison; Lechtenberg, Lara; Prewitt, Maureen; Gracia, Clarisa

2016-12-01

To evaluate reproductive hormone patterns in women exposed to alkylating-agent chemotherapy. Prospective cohort. University hospital. Normally menstruating mid-reproductive-age women (20-35 years old) who had previously been exposed to alkylating-agent chemotherapy for cancer treatment were compared with two healthy control populations: similarly-aged women and late-reproductive-age women (43-50 years old). Subjects collected daily urine samples for one cycle. Integrated urinary pregnanediol glucuronide (PDG) and estrone conjugate (E1c) and urinary excretion of gonadotropins (FSH and LH). Thirty-eight women (13 survivors, 11 same-age control subjects, 14 late-reproductive-age control subjects) provided 1,082 urine samples. Cycle length, luteal phase length, and evidence of luteal activity were similar among the groups. As expected, ovarian reserve was impaired in cancer survivors compared with same-age control subjects but similar between survivors and late-reproductive-age control subjects. In contrast, survivors had total and peak PDG levels that were similar to same-age control subjects and higher than those observed in late-reproductive-age control subjects. Survivors had higher E1c levels than both same-age and late-reproductive-age control subjects. There was no difference in urinary gonadotropins among the groups. Women exposed to alkylating agents have a unique reproductive hormone milieu that is not solely explained by age or ovarian reserve. The urinary hormone profile observed in survivors appears more similar to same-age control subjects than to late-reproductive-age women with similar ovarian reserve, which may suggest that age plays a more important role than ovarian reserve in the follicular dynamics of survivors. Copyright © 2016 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Impact of Therapy Sequence with Alkylating Agents and MGMT Status in Patients with Advanced Neuroendocrine Tumors.

Science.gov (United States)

Krug, Sebastian; Boch, Michael; Rexin, Peter; Gress, Thomas M; Michl, Patrick; Rinke, Anja

2017-05-01

Alkylating chemotherapeutics with either a streptozotocin-(STZ) or temozolomide-(TEM) backbone are routinely used in patients with progressive and unresectable pancreatic neuroendocrine tumors (PNET). In addition, dacarbazine (DTIC) was described as an alternative alkylating therapy option for PNETs. The optimal treatment sequence with alkylating compounds and a potential use of O6-methylguanine-DNA methyltransferase (MGMT) level as predictive biomarker have not yet been sufficiently elucidated. The aim of our study was the evaluation of therapy sequence with either STZ-based treatment followed by DTIC (group A) or the inverse schedule with upfront DTIC (group B) and to correlate MGMT status with clinicopathological characteristics and response to therapy. We retrospectively analyzed 28 patients with neuroendocrine tumors (NET) who were treated with STZ-based therapy and DTIC. Additionally, in a second group MGMT immunohistochemistry was performed from primary and metastatic tumor sites. For statistical evaluation Kaplan-Meier analysis, Cox regression methods and Fisher's exact test were used. There was no difference of objective response and disease control between either STZ-based therapy followed by DTIC treatment (group A) after progression or the reverse sequence (group B). Median time to progression (TTP) was estimated to be 21 months in both arms. First-line STZ-based chemotherapy was not superior to first-line DTIC treatment (16 vs. 13 months; p=0.8). MGMT status did not correlate with clinicopathological characteristics or response to therapy with these alkylating agents. Upfront chemotherapy with either STZ-based treatment or DTIC monotherapy showed similar efficacy and median TTP rates. In this study, MGMT protein expression assessed by immunohistochemistry did not play an important role as a predictive marker for alkylating agents. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

Synthesis of omega-hydroxy carboxylic acids and alpha,omega-dimethyl ketones using alpha,omega-diols as alkylating agents.

Science.gov (United States)

Iuchi, Yosuke; Hyotanishi, Megumi; Miller, Brittany E; Maeda, Kensaku; Obora, Yasushi; Ishii, Yasutaka

2010-03-05

Synthesis of omega-hydroxy carboxylic acids and alpha,omega-dimethyl diketones was successfully achieved by using alpha,omega-diols as alkylating agents under the influence of an iridium catalyst. For example, the alkylation of butyl cyanoacetate with 1,13-tridecanediol in the presence of [IrCl(cod)](2) or [IrCl(coe)(2)](2) gave rise to butyl 2-cyano-15-hydroxypentadecanoate in good yield which is easily converted to cyclopentadecanolide (CPDL). In addition, the alkylation of acetone with 1,10-decanediol in the presence of [IrCl(cod)](2) and KOH resulted in an important muscone precursor, 2,15-hexadecanedione (HDDO), in good yield.

Histone H2AX is a critical factor for cellular protection against DNA alkylating agents.

Science.gov (United States)

Meador, J A; Zhao, M; Su, Y; Narayan, G; Geard, C R; Balajee, A S

2008-09-25

Histone H2A variant H2AX is a dose-dependent suppressor of oncogenic chromosome translocations. H2AX participates in DNA double-strand break repair, but its role in other DNA repair pathways is not known. In this study, role of H2AX in cellular response to alkylation DNA damage was investigated. Cellular sensitivity to two monofunctional alkylating agents (methyl methane sulfonate and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)) was dependent on H2AX dosage, and H2AX null cells were more sensitive than heterozygous cells. In contrast to wild-type cells, H2AX-deficient cells displayed extensive apoptotic death due to a lack of cell-cycle arrest at G(2)/M phase. Lack of G(2)/M checkpoint in H2AX null cells correlated well with increased mitotic irregularities involving anaphase bridges and gross chromosomal instability. Observation of elevated poly(ADP) ribose polymerase 1 (PARP-1) cleavage suggests that MNNG-induced apoptosis occurs by PARP-1-dependent manner in H2AX-deficient cells. Consistent with this, increased activities of PARP and poly(ADP) ribose (PAR) polymer synthesis were detected in both H2AX heterozygous and null cells. Further, we demonstrate that the increased PAR synthesis and apoptotic death induced by MNNG in H2AX-deficient cells are due to impaired activation of mitogen-activated protein kinase pathway. Collectively, our novel study demonstrates that H2AX, similar to PARP-1, confers cellular protection against alkylation-induced DNA damage. Therefore, targeting either PARP-1 or histone H2AX may provide an effective way of maximizing the chemotherapeutic value of alkylating agents for cancer treatment.

Automated synthesis of an {sup 18}F-labelled pyridine-based alkylating agent for high yield oligonucleotide conjugation

Energy Technology Data Exchange (ETDEWEB)

Guggenberg, Elisabeth von; Sader, Jayden A.; Wilson, John S.; Shahhosseini, Soraya; Koslowsky, Ingrid; Wuest, Frank [Edmonton PET Centre, Division of Oncologic Imaging, Department of Oncology, Cross Cancer Institute, 11560 University Ave, Edmonton, AB, T6G 1Z2 (Canada); Mercer, John R. [Edmonton PET Centre, Division of Oncologic Imaging, Department of Oncology, Cross Cancer Institute, 11560 University Ave, Edmonton, AB, T6G 1Z2 (Canada)], E-mail: johnmerc@cancerboard.ab.ca

2009-09-15

Alkylating agents have been shown to be very promising for the radiolabelling of oligonucleotides with fluorine-18. In this report we describe the fully automated synthesis of 2-bromo-N-[3-(2-[{sup 18}F]fluoropyridin-3-yloxy)propyl]acetamide ([{sup 18}F]FPyBrA) utilizing a modular synthesis unit. Reaction conditions for the coupling of this pyridine-based alkylating agent at the 5' end of a fully phosphorothioated random 20-mer DNA sequence were optimized to achieve very high radiochemical yields (>90%) and a maximum specific activity of 5-6 GBq/{mu}moL. The potential for rapid purification by solid phase extraction without need of chromatographic isolation of the radiolabelled oligonucleotide presents an overall benefit for the application of oligonucleotides in preclinical studies and potential clinical applications.

Profiling the nucleobase and structure selectivity of anticancer drugs and other DNA alkylating agents by RNA sequencing.

Science.gov (United States)

Gillingham, Dennis; Sauter, Basilius

2018-05-06

Drugs that covalently modify DNA are components of most chemotherapy regimens, often serving as first-line treatments. Classically the chemical reactivity of DNA alkylators has been determined in vitro with short oligonucleotides. Here we use next generation RNA sequencing to report on the chemoselectivity of alkylating agents. We develop the method with the well-known clinically used DNA modifiying drugs streptozotocin and temozolomide, and then apply the technique to profile RNA modification with uncharacterized alkylation reactions such as with powerful electrophiles like trimethylsilyldiazomethane. The multiplexed and massively parallel format of NGS offers analyses of chemical reactivity in nucleic acids to be accomplished in less time with greater statistical power. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stability of solutions of antineoplastic agents during preparation and storage for in vitro assays. General considerations, the nitrosoureas and alkylating agents.

Science.gov (United States)

Bosanquet, A G

1985-01-01

In vitro drug sensitivity of tumour biopsies is currently being determined using a variety of methods. For these chemosensitivity assays many drugs are required at short notice, and this in turn means that the drugs must generally be stored in solution. There are, however, a number of potential problems associated with dissolving and storing drugs for in vitro use, which include (a) drug adsorption; (b) effects of freezing; (c) drug stability under the normal conditions of dilution and setting up of an in vitro assay; and (d) insolubility of drugs in normal saline (NS) or phosphate-buffered saline (PBS). These problems are considered in general, and some recommendations for use of solutions of drugs in in vitro assays are suggested. The nitrosoureas and alkylating agents are also investigated in greater detail in this respect. The nitrosoureas are found to be very labile in PBS at pH 7, with 5% degradation (t0.95) occurring in 10-50 min at room temperature. These values are increased about 10-fold on refrigeration and about 5- to 10-fold on reduction of the pH of the medium to pH 4-5. At pH 7 and room temperature, t0.95 is observed in under 1 h with the alkylating agents nitrogen mustard, chlorambucil, melphalan, 2,5-diaziridinyl-3,6-bis(2-hydroxyethylamino)-1,4-benzoquinone (BZQ), dibromodulcitol, dibromomannitol, treosulphan, and procarbazine. Of the other alkylating agents, 4-hydroperoxycylophosphamide (sometimes used in vitro in place of cyclophosphamide), busulphan, dianhydrogalactitol, aziridinylbenzoquinone (AZQ), and dacarbazine have a t0.95 of between 2 and 24 h, while ifosfamide and pentamethylmelamine are both stable in aqueous solution for greater than 7 days. About half the drugs studied in detail have been stored frozen in solution for in vitro use, although very little is known about their stability under these conditions.

Immunological detection and quantification of DNA components structurally modified by alkylating carcinogens, mutagens and chemotherapeutic agents

International Nuclear Information System (INIS)

Rajewsky, M.F.

1983-01-01

The detection and quantification of defined reaction products of chemical mutagens and carcinogens (and of many cancer chemotherapeutic agents) with DNA require highly sensitive analytical techniques. The exceptional capability of immunoglobulins to recognize subtle alterations of molecular structure (especially when monoclonal antibodies are used to maximize specificity), outstanding sensitivity of immunoanalysis by high-affinity antibodies, and the fact that radioactively-labelled agents are not required suggest the utility of a radioimmunoassay to recognize and quantitate alkylated DNA products. We have recently developed a set of high-affinity monoclonal antibodies (secreted by mouse x mouse as well as by rat x rat hybridomas; antibody affinity constants, 10 9 to > 10 10 lmol) specifically directed against several DNA alkylation products with possible relevance in relation to both mutagenesis and malignant transformation of mammalian cells. These alkylation products include 0 6 -N-butyldeoxyguanosine, and 0 4 -ethyldeoxythymidine. When used in a radioimmunassay, an antibody specific for 0 6 -ethyldeoxyguanosine, for example, will detect this product at an 0 6 -ethyldeoxyguanosine/deoxyguanosine molar ratio of approx. 3 x 10 -7 in a hydrolysate of 100 ug of DNA. The limit of detection can be lowered further if the respective alkyldeoxynucleosides are separated by HPLC from the DNA hydrolysate prior to the RIA. The anti-alkyldeoxynucleoside monoclonal antibodies can also be used to visualize, by immunostaining and fluorescence microscopy combined with electronic image intensification, specific alkylation products in the nuclear DNA of individual cells, and to localize structurally modified bases in double-stranded DNA molecules by transmission electron microscopy

Interfce alkylation of ethyldiphenylphosphinylacetate

International Nuclear Information System (INIS)

Yarkevich, A.N.; Tsvetkov, E.N.

1994-01-01

The paper deals with the alkylation of the methyline group of ethyldiphenylphosphinylacetate (1) by different alkylating agents in the presence of Cs 2 CO 3 . In all cases the application of Cs 2 CO 3 results in a significant increase of reaction rate. 10 refs., 3 tabs

Sulfonium Salts as Alkylating Agents for Palladium-Catalyzed Direct Ortho Alkylation of Anilides and Aromatic Ureas.

Science.gov (United States)

Simkó, Dániel Cs; Elekes, Péter; Pázmándi, Vivien; Novák, Zoltán

2018-02-02

A novel method for the ortho alkylation of acetanilide and aromatic urea derivatives via C-H activation was developed. Alkyl dibenzothiophenium salts are considered to be new reagents for the palladium-catalyzed C-H activation reaction, which enables the transfer of methyl and other alkyl groups from the sulfonium salt to the aniline derivatives under mild catalytic conditions.

Induction of specific Escherichia coli genes by sublethal treatments with alkylating agents.

OpenAIRE

Volkert, M R; Nguyen, D C

1984-01-01

Fusions of the lac operon to genes induced by treatment with sublethal levels of alkylating agents have been selected from random insertions of the Mu-dl(ApRlac) phage by screening for induction of beta-galactosidase activity in the presence of methyl methanesulfonate. Genetic analysis reveals that these fusions resulted from insertion of Mu-dl(ApRlac) into two regions of the chromosome. One region (aidA) is near his and, based on phenotypic effects, appears to represent insertion into the al...

Contributions of DNA repair and damage response pathways to the non-linear genotoxic responses of alkylating agents

Science.gov (United States)

Klapacz, Joanna; Pottenger, Lynn H.; Engelward, Bevin P.; Heinen, Christopher D.; Johnson, George E.; Clewell, Rebecca A.; Carmichael, Paul L.; Adeleye, Yeyejide; Andersen, Melvin E.

2016-01-01

From a risk assessment perspective, DNA-reactive agents are conventionally assumed to have genotoxic risks at all exposure levels, thus applying a linear extrapolation for low-dose responses. New approaches discussed here, including more diverse and sensitive methods for assessing DNA damage and DNA repair, strongly support the existence of measurable regions where genotoxic responses with increasing doses are insignificant relative to control. Model monofunctional alkylating agents have in vitro and in vivo datasets amenable to determination of points of departure (PoDs) for genotoxic effects. A session at the 2013 Society of Toxicology meeting provided an opportunity to survey the progress in understanding the biological basis of empirically-observed PoDs for DNA alkylating agents. Together with the literature published since, this review discusses cellular pathways activated by endogenous and exogenous alkylation DNA damage. Cells have evolved conserved processes that monitor and counteract a spontaneous steady-state level of DNA damage. The ubiquitous network of DNA repair pathways serves as the first line of defense for clearing of the DNA damage and preventing mutation. Other biological pathways discussed here that are activated by genotoxic stress include post-translational activation of cell cycle networks and transcriptional networks for apoptosis/cell death. The interactions of various DNA repair and DNA damage response pathways provide biological bases for the observed PoD behaviors seen with genotoxic compounds. Thus, after formation of DNA adducts, the activation of cellular pathways can lead to the avoidance a mutagenic outcome. The understanding of the cellular mechanisms acting within the low-dose region will serve to better characterize risks from exposures to DNA-reactive agents at environmentally-relevant concentrations. PMID:27036068

Sensitivity of HTB140 cell exposed to protons and alkylating agents

International Nuclear Information System (INIS)

Koricanac, L.; Petrovic, I.; Privitera, G.; Cuttone, G.; Ristic-Fira, A.

2006-01-01

Malignant melanoma is a highly aggressive cancer with a poor prognosis due to resistance to radiotherapy and chemotherapy regimens. The mainstay of treatment remains DNA-alkylating agent dacarbazine (DTIC). Fotemustine (FM), chloroethylnitrosourea agent, also has demonstrated significant antitumoral effects in malignant melanoma. However, the resistance of melanoma cells limits their clinical application. In order to enhance the inhibition of melanoma cell growth, in this study, combined treatment of FM and DTIC with proton irradiation, was investigated. We analyzed the effects of combined treatment on HTB140 melanoma cell viability and proliferation. Significant inhibition of cell growth, especially cell proliferation, was obtained after treatment with protons and FM compare to single irradiation or drug treatment. Treatment with protons and DTIC has shown improved growth inhibition compare to appropriate single drug treatment, but not compare to irradiation as a single treatment. (author)

Beyond Alkylating Agents for Gliomas: Quo Vadimus?

Science.gov (United States)

Puduvalli, Vinay K; Chaudhary, Rekha; McClugage, Samuel G; Markert, James

2017-01-01

Recent advances in therapies have yielded notable success in terms of improved survival in several cancers. However, such treatments have failed to improve outcome in patients with gliomas for whom surgery followed by radiation therapy and chemotherapy with alkylating agents remain the standard of care. Genetic and epigenetic studies have helped identify several alterations specific to gliomas. Attempts to target these altered pathways have been unsuccessful due to various factors, including tumor heterogeneity, adaptive resistance of tumor cells, and limitations of access across the blood-brain barrier. Novel therapies that circumvent such limitations have been the focus of intense study and include approaches such as immunotherapy, targeting of signaling hubs and metabolic pathways, and use of biologic agents. Immunotherapeutic approaches including tumor-targeted vaccines, immune checkpoint blockade, antibody-drug conjugates, and chimeric antigen receptor-expressing cell therapies are in various stages of clinical trials. Similarly, identification of key metabolic pathways or converging hubs of signaling pathways that are tumor specific have yielded novel targets for therapy of gliomas. In addition, the failure of conventional therapies against gliomas has led to a growing interest among patients in the use of alternative therapies, which in turn has necessitated developing evidence-based approaches to the application of such therapies in clinical studies. The development of these novel approaches bears potential for providing breakthroughs in treatment of more meaningful and improved outcomes for patients with gliomas.

MGMT: key node in the battle against genotoxicity, carcinogenicity and apoptosis induced by alkylating agents.

Science.gov (United States)

Kaina, Bernd; Christmann, Markus; Naumann, Steffen; Roos, Wynand P

2007-08-01

O(6)-methylguanine-DNA methyltransferase (MGMT) plays a crucial role in the defense against alkylating agents that generate, among other lesions, O(6)-alkylguanine in DNA (collectively termed O(6)-alkylating agents [O(6)AA]). The defense is highly important, since O(6)AA are common environmental carcinogens, are formed endogenously during normal cellular metabolism and possibly inflammation, and are being used in cancer therapy. O(6)AA induced DNA damage is subject to repair, which is executed by MGMT, AlkB homologous proteins (ABH) and base excision repair (BER). Although this review focuses on MGMT, the mechanism of repair by ABH and BER will also be discussed. Experimental systems, in which MGMT has been modulated, revealed that O(6)-methylguanine (O(6)MeG) and O(6)-chloroethylguanine are major mutagenic, carcinogenic, recombinogenic, clastogenic and killing lesions. O(6)MeG-induced clastogenicity and cell death require MutS alpha-dependent mismatch repair (MMR), whereas O(6)-chloroethylguanine-induced killing occurs independently of MMR. Extensive DNA replication is required for O(6)MeG to provoke cytotoxicity. In MGMT depleted cells, O(6)MeG induces apoptosis almost exclusively, barely any necrosis, which is presumably due to the remarkable ability of secondarily formed DNA double-strand breaks (DSBs) to trigger apoptosis via ATM/ATR, Chk1, Chk2, p53 and p73. Depending on the cellular background, O(6)MeG activates both the death receptor and the mitochondrial apoptotic pathway. The inter-individual expression of MGMT in human lymphocytes is highly variable. Given the key role of MGMT in cellular defense, determination of MGMT activity could be useful for assessing a patient's drug sensitivity. MGMT is expressed at highly variable amounts in human tumors. In gliomas, a correlation was found between MGMT activity, MGMT promoter methylation and response to O(6)AA. Although the human MGMT gene is inducible by glucocorticoids and genotoxins such as radiation and

Evaluation of the persistence in the induction of Sister Chromatid Exchanges (SCE) by alkylating agents

International Nuclear Information System (INIS)

Rodriguez R, R.; Huerta V, C.; MOrales R, P.R.

2006-01-01

The persistence in the induction of sister chromatid exchanges (SCE) by the alkylating agents methyl and ethyl-methanesulfonates (MMS and EMS) was evaluated. For it, to groups of mice its were administered a dose of these agents and later its were analyzed the induced SCE's in two periods: early and late. Both agents caused high increments of SCE in the early period and small in the late one; however, the caused lately by EMS was significantly bigger. This late induction of SCE by EMS possibly is associated with an epigenetic change or with the presence of etiladucts in the phosphodiester bonds of the DNA. (Author)

The alkylation of imine anions formation of enamines

NARCIS (Netherlands)

Heiszwolf, G.J.; Kloosterziel, H.

1970-01-01

The ambident anions derived from imines were alkylated using a variety of solvents and alkylating agents. Under reactive conditions enamines (N-alkylation) are formed as the main products instead of the usually obsd. homologous imines (C-alkylation). The influence of the type of imine, solvent, and

An aCGH classifier derived from BRCA1-mutated breast cancer and benefit of high-dose platinum-based chemotherapy in HER2-negative breast cancer patients

NARCIS (Netherlands)

Vollebergh, M. A.; Lips, E. H.; Nederlof, P. M.; Wessels, L. F. A.; Schmidt, M. K.; van Beers, E. H.; Cornelissen, S.; Holtkamp, M.; Froklage, F. E.; de Vries, E. G. E.; Schrama, J. G.; Wesseling, J.; van de Vijver, M. J.; van Tinteren, H.; de Bruin, Michiel; Hauptmann, M.; Rodenhuis, S.; Linn, S. C.

2011-01-01

Breast cancer cells deficient for BRCA1 are hypersensitive to agents inducing DNA double-strand breaks (DSB), such as bifunctional alkylators and platinum agents. Earlier, we had developed a comparative genomic hybridisation (CGH) classifier based on BRCA1-mutated breast cancers. We hypothesised

Genomic patterns resembling BRCA1- and BRCA2-mutated breast cancers predict benefit of intensified carboplatin-based chemotherapy

NARCIS (Netherlands)

Vollebergh, Marieke A.; Lips, Esther H.; Nederlof, Petra M.; Wessels, Lodewyk F. A.; Wesseling, Jelle; Vd Vijver, Marc J.; de Vries, Elisabeth G. E.; van Tinteren, Harm; Jonkers, Jos; Hauptmann, Michael; Rodenhuis, Sjoerd; Linn, Sabine C.

2014-01-01

BRCA-mutated breast cancer cells lack the DNA-repair mechanism homologous recombination that is required for error-free DNA double-strand break (DSB) repair. Homologous recombination deficiency (HRD) may cause hypersensitivity to DNA DSB-inducing agents, such as bifunctional alkylating agents and

Inhibition of RecBCD enzyme by antineoplastic DNA alkylating agents.

Science.gov (United States)

Dziegielewska, Barbara; Beerman, Terry A; Bianco, Piero R

2006-09-01

To understand how bulky adducts might perturb DNA helicase function, three distinct DNA-binding agents were used to determine the effects of DNA alkylation on a DNA helicase. Adozelesin, ecteinascidin 743 (Et743) and hedamycin each possess unique structures and sequence selectivity. They bind to double-stranded DNA and alkylate one strand of the duplex in cis, adding adducts that alter the structure of DNA significantly. The results show that Et743 was the most potent inhibitor of DNA unwinding, followed by adozelesin and hedamycin. Et743 significantly inhibited unwinding, enhanced degradation of DNA, and completely eliminated the ability of the translocating RecBCD enzyme to recognize and respond to the recombination hotspot chi. Unwinding of adozelesin-modified DNA was accompanied by the appearance of unwinding intermediates, consistent with enzyme entrapment or stalling. Further, adozelesin also induced "apparent" chi fragment formation. The combination of enzyme sequestering and pseudo-chi modification of RecBCD, results in biphasic time-courses of DNA unwinding. Hedamycin also reduced RecBCD activity, albeit at increased concentrations of drug relative to either adozelesin or Et743. Remarkably, the hedamycin modification resulted in constitutive activation of the bottom-strand nuclease activity of the enzyme, while leaving the ability of the translocating enzyme to recognize and respond to chi largely intact. Finally, the results show that DNA alkylation does not significantly perturb the allosteric interaction that activates the enzyme for ATP hydrolysis, as the efficiency of ATP utilization for DNA unwinding is affected only marginally. These results taken together present a unique response of RecBCD enzyme to bulky DNA adducts. We correlate these effects with the recently determined crystal structure of the RecBCD holoenzyme bound to DNA.

[Genetic differences in mice in the sensitivity to the immunodepressive action of alkylating agents].

Science.gov (United States)

Kim, N I; Telegin, L Iu; Pevnitskiĭ, L A

1983-04-01

The immunodepressant action of cyclophosphamide, thiophosphamide and sarcolysine was examined in experimental primary immune response in mice of different lines immunized with sheep red blood cells. DBA/2 and C3H/Sn mice were marked by the highest sensitivity to the immunodepressant action of the alkylating agents. BALB/c mice were relatively resistant to the immunodepressant action. Possible reasons for the interspecific differences found are discussed.

A new approach in the preparation of dendrimer-based bifunctional diethylenetriaminepentaacetic acid MR contrast agent derivatives.

Science.gov (United States)

Nwe, Kido; Xu, Heng; Regino, Celeste Aida S; Bernardo, Marcelino; Ileva, Lilia; Riffle, Lisa; Wong, Karen J; Brechbiel, Martin W

2009-07-01

In this paper, we report a new method to prepare and characterize a contrast agent based on a fourth-generation (G4) polyamidoamine (PAMAM) dendrimer conjugated to the gadolinium complex of the bifunctional diethylenetriamine pentaacetic acid derivative (1B4M-DTPA). The method involves preforming the metal-ligand chelate in alcohol prior to conjugation to the dendrimer. The dendrimer-based agent was purified by a Sephadex G-25 column and characterized by elemental analysis. The analysis and SE-HPLC data gave a chelate to dendrimer ratio of 30:1 suggesting conjugation at approximately every other amine terminal on the dendrimer. Molar relaxivity of the agent measured at pH 7.4 displayed a higher value than that of the analogous G4 dendrimer based agent prepared by the postmetal incorporation method (r(1) = 26.9 vs 13.9 mM(-1) s(-1) at 3 T and 22 degrees C). This is hypothesized to be due to the higher hydrophobicity of this conjugate and the lack of available charged carboxylate groups from noncomplexed free ligands that might coordinate to the metal and thus also reduce water exchange sites. Additionally, the distribution populations of compounds that result from the postmetal incorporation route are eliminated from the current product simplifying characterization as quality control issues pertaining to the production of such agents for clinical use as MR contrast agents. In vivo imaging in mice showed a reasonably fast clearance (t(1/2) = 24 min) suggesting a viable agent for use in clinical application.

Contributions of DNA repair and damage response pathways to the non-linear genotoxic responses of alkylating agents.

Science.gov (United States)

Klapacz, Joanna; Pottenger, Lynn H; Engelward, Bevin P; Heinen, Christopher D; Johnson, George E; Clewell, Rebecca A; Carmichael, Paul L; Adeleye, Yeyejide; Andersen, Melvin E

2016-01-01

From a risk assessment perspective, DNA-reactive agents are conventionally assumed to have genotoxic risks at all exposure levels, thus applying a linear extrapolation for low-dose responses. New approaches discussed here, including more diverse and sensitive methods for assessing DNA damage and DNA repair, strongly support the existence of measurable regions where genotoxic responses with increasing doses are insignificant relative to control. Model monofunctional alkylating agents have in vitro and in vivo datasets amenable to determination of points of departure (PoDs) for genotoxic effects. A session at the 2013 Society of Toxicology meeting provided an opportunity to survey the progress in understanding the biological basis of empirically-observed PoDs for DNA alkylating agents. Together with the literature published since, this review discusses cellular pathways activated by endogenous and exogenous alkylation DNA damage. Cells have evolved conserved processes that monitor and counteract a spontaneous steady-state level of DNA damage. The ubiquitous network of DNA repair pathways serves as the first line of defense for clearing of the DNA damage and preventing mutation. Other biological pathways discussed here that are activated by genotoxic stress include post-translational activation of cell cycle networks and transcriptional networks for apoptosis/cell death. The interactions of various DNA repair and DNA damage response pathways provide biological bases for the observed PoD behaviors seen with genotoxic compounds. Thus, after formation of DNA adducts, the activation of cellular pathways can lead to the avoidance of a mutagenic outcome. The understanding of the cellular mechanisms acting within the low-dose region will serve to better characterize risks from exposures to DNA-reactive agents at environmentally-relevant concentrations. Copyright © 2015 Elsevier B.V. All rights reserved.

Photo-triggered fluorescent theranostic prodrugs as DNA alkylating agents for mechlorethamine release and spatiotemporal monitoring.

Science.gov (United States)

Cao, Yanting; Pan, Rong; Xuan, Weimin; Wei, Yongyi; Liu, Kejian; Zhou, Jiahong; Wang, Wei

2015-06-28

We describe a new theranostic strategy for selective delivery and spatiotemporal monitoring of mechlorethamine, a DNA alkylating agent. A photo-responsive prodrug is designed and composed of a photolabile o-nitrophenylethyl group, a DNA alkylating mechlorethamine drug and a coumarin fluorophore. Masking of the "N" in mechlorethamine in a positively charged state in the prodrug renders it inactive, non-toxic, selective and non-fluorescent. Indeed, the stable prodrug shows negligible cytotoxicity towards normal cells with and without UV activation and is completely non-fluorescent. However, upon photo-irradiation, the active mechlorethamine is released and induces efficient DNA cross-links, accompanied by a strong fluorescence enhancement (152 fold). Furthermore, DNA cross-linking activity from the release can be transformed into anticancer activity observed in in vitro studies of tumor cells. Importantly, the drug release progress and the movement can be conveniently monitored by fluorescence spectroscopy. The mechanistic study proves that the DNA cross-linking activity is mainly due to the release of DNA alkylating mechlorethamine. Altogether, the studies show the power of the theranostic strategy for efficient therapy in cancer treatment.

Mutants of Aspergillus nidulans with increased resistance to the alkylating agent, N-methyl-N'-nitro-N-nitrosoguanidine.

Science.gov (United States)

Hooley, P; Shawcross, S G; Strike, P

1988-05-01

The isolation and characterisation of mutants of Aspergillus nidulans showing resistance to MNNG is described. Such isolates were stable through prolonged subculture in the absence of the selective agent, and resistance segregated as an allele of a single gene in meiotic and mitotic analysis. MNNG-resistant strains showed an increase in resistance to EMS and UV irradiation but no cross-resistance to MMS was detected. Possible mechanisms of resistance to alkylating agents are discussed.

Therapeutic journery of nitrogen mustard as alkylating anticancer agents: Historic to future perspectives.

Science.gov (United States)

Singh, Rajesh K; Kumar, Sahil; Prasad, D N; Bhardwaj, T R

2018-05-10

Cancer is considered as one of the most serious health problems today. The discovery of nitrogen mustard as an alkylating agent in 1942, opened a new era in the cancer chemotherapy. This valuable class of alkylating agent exerts its biological activity by binding to DNA, cross linking two strands, preventing DNA replication and ultimate cell death. At the molecular level, nitrogen lone pairs of nitrogen mustard generate a strained intermediate "aziridinium ion" which is very reactive towards DNA of tumor cell as well as normal cell resulting in various adverse side effects alogwith therapeutic implications. Over the last 75 years, due to its high reactivity and peripheral cytotoxicity, numerous modifications have been made in the area of nitrogen mustard to improve its efficacy as well as enhancing drug delivery specifically to tumor cells. This review mainly discusses the medicinal chemistry aspects in the development of various classes of nitrogen mustards (mechlorethamine, chlorambucil, melphalan, cyclophosphamide and steroidal based nitrogen mustards). The literature collection includes the historical and the latest developments in these areas. This comprehensive review also attempted to showcase the recent progress in the targeted delivery of nitrogen mustards that includes DNA directed nitrogen mustards, antibody directed enzyme prodrug therapy (ADEPT), gene directed enzyme prodrug therapy (GDEPT), nitrogen mustard activated by glutathione transferase, peptide based nitrogen mustards and CNS targeted nitrogen mustards. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Microtubule disruption induced in vivo by alkylation of beta-tubulin by 1-aryl-3-(2-chloroethyl)ureas, a novel class of soft alkylating agents.

Science.gov (United States)

Legault, J; Gaulin, J F; Mounetou, E; Bolduc, S; Lacroix, J; Poyet, P; Gaudreault, R C

2000-02-15

We have previously reported that 4-tert-butyl-[3-(2-chloroethyl)ureido] benzene (4-tBCEU), a potent cytotoxic agent, modulates the synthesis of tubulins, suggesting that its cytotoxicity may be mediated through an antimicrotubule mechanism. Indeed, 4-tBCEU and its 4-iso-propyl (4-isopropyl [3-(2-chloroethyl)ureido] benzene) and 4-sec-butyl (4-sec-butyl [3-(2-chloroethyl)ureido] benzene) homologues induced disruption of the cytoskeleton and arrest of the cell cycle in G2 transition and mitosis. To better understand the mechanisms responsible for microtubule disruption by 1-aryl-3-(2-chloroethyl)ureas (CEU), we first examined their cytotoxicity on Chinese hamster ovary cells resistant to vinblastine and colchicine due to the expression of mutated tubulins (CHO-VV 3-2). These cells showed resistance to CEU, e.g., 4-tBCEU having an IC50 of 21.3+/-1.1 microM as compared with an IC50 of 11.6+/-0.7 microM for wild-type cells, suggesting a direct effect of the drugs on tubulins. Western blot analysis confirmed the disruption of microtubules and evidenced the formation of an additional immunoreactive beta-tubulin with an apparent lower molecular weight on SDS polyacrylamide gel. Incubation of MDA-MB-231 cells with [urea-14C]-4-tBCEU revealed the presence of a radioactive protein that coincided with the additional beta-tubulin band, indicating that CEU could covalently bind to the beta-tubulin. The 4-tBCEU-binding site on beta-tubulin was identified by competition of the CEU with colchicine, vinblastine, and iodoacetamide, a specific alkylating agent of sulfhydryl groups of cysteine residues. Colchicine, but not vinblastine, prevented the formation of the additional beta-tubulin band, suggesting that 4-tBCEU alkylates either Cys239 or Cys354 residues near the colchicine-binding site. To determine the cysteine residue alkylated by 4-tBCEU, we incubated the radiolabeled drug with human neuroblastoma cells (SK-N-SH) that overexpress the betaIII-tubulin, an isoform where Cys239

Williamson alkylation approach to the synthesis of poly(alkyl vinyl ether) copolymers

International Nuclear Information System (INIS)

Markova, D.; Christova, D.; Velichkova, R.

2008-01-01

A method for synthesis of poly(alkyl vinyl ether-co-vinyl alcohol) copolymers was developed based on the Williamson's alkylation of poly(vinyl acetate) (PVAc) with alkyl iodides. The influence of the alkylating agent and the reaction conditions on the efficiency of the modification reaction was investigated. The copolymers obtained were characterized by means of 1 H NMR and GPC. It was proved that by applying the proposed method copolymers of different composition and properties containing methyl vinyl ether, ethyl vinyl ether as well as n-butyl vinyl ether units could be prepared. Poly(methyl vinyl ether-co-vinyl alcohol)s of high degree of methylation exhibit sharp temperature response at 38-39 deg C in aqueous solution typical of the so-called smart polymers. (authors)

Reichardt's dye and its reactions with the alkylating agents 4-chloro-1-butanol, ethyl methanesulfonate, 1-bromobutane and Fast Red B - a potentially useful reagent for the detection of genotoxic impurities in pharmaceuticals.

Science.gov (United States)

Corrigan, Damion K; Whitcombe, Michael J; McCrossen, Sean; Piletsky, Sergey

2009-04-01

Alkylating agents are potentially genotoxic impurities that may be present in drug products. These impurities occur in pharmaceuticals as by-products from the synthetic steps involved in drug production, as impurities in starting materials or from in-situ reactions that take place in the final drug product. Currently, analysis for genotoxic impurities is typically carried out using either HPLC/MS or GC/MS. These techniques require specialist expertise, have long analysis times and often use sample clean-up procedures. Reichardt's dye is well known for its solvatochromic properties. In this paper the dye's ability to undergo alkylation is reported. The reaction between Reichardt's dye and alkylating agents such as 4-chloro-1-butanol and ethyl methanesulfonate was monitored spectrophotometrically at 618 nm in acetonitrile and 624 nm in N,N-dimethylformamide. Changes in absorption were observed using low levels of alkylating agent (5-10 parts per million). Alkylation of the dye with 4-chloro-1-butanol and ethyl methanesulfonate was confirmed. Reichardt's dye, and its changing UV absorption, was examined in the presence of paracetamol (10 and 100 mg/ml). Whilst the alkylation-induced changes in UV absorption were not as pronounced as with standard solutions, detection of alkylation was still possible. Using standard solutions and in the presence of a drug matrix, Reichardt's dye shows promise as a reagent for detection of low levels of industrially important alkylating agents.

Mutagenic effects of alkylating agents on prophage lambda

Energy Technology Data Exchange (ETDEWEB)

Bresler, S.; Kalinin, V.L.; Kuznetsova, L.V.

1984-06-01

An evaluation was made of the relative contribution of repair and reparative mechanisms to the mutagenic potency of several alkylating agents on thermoinducible prophage lambdacI857 ind/sup -/ in several stains of E. coli. Following treatment of lysogenic E. coli with the mutagens and heat induction, 0.02 N-nitroso-N-methylurea (NMU) induced c mutations with a high frequency (ca. 10%) in both wild type E. coli and cells with repair mutations (recA13, lexA102, uvrA6, umuC36, xthA9, recF143, polA1, uvrD3, uvrD502). It appears that NUM-induced mutations are stabilized as replicative errors due to mismatched, altered bases. Delay in induction following exposure to NMU improves prophage survival and diminishes c mutant formation, regardless of the E. coli genotype. Evidently, carbamoylation is not involved in NMU mutagenicity since 0.02 M KNCO is nonmutagenic and is virtually without effect on prophage viability. Replicative mechanisms are also involved in N-methyl-N'-nitro-N-nitrosoguanidine (15%) and ethyl methanesulfonate (2%) induced mutations, since the maximum yield of mutants was independent of recA/sup +/ genotype. However, the mutagenicity of methyl methanesulfonate was abolished by the recA mutation, indicating that the mutagenicity of this agent is repair-dependent. Mitomycin C (0.1%) and acridine mustard (0.3%) induce c mutations regardless of recA/sup +/ and, therefore, appear to do so by intercalation. 26 references, 6 figures.

Residual injury to the hemopoietic microenvironment following sequential radiation and alkylating agents

International Nuclear Information System (INIS)

Wathen, L.M.K.

1981-01-01

To assess the hemopoietic impact following combined therapy, mice received intraperitoneal doses of cyclophosphamide one week after 1500 rad leg irradiation. This treatment inhibited repopulation of endogenous nucleated cells to less than 60% of normal. Leg irradiation alone repressed the repopulation to about 75% of normal and cyclophosphamide alone suppressed to 80% of normal. Differential marrow counts revealed that marrow stromal cells were suppressed to less than 30% normal for 3 months following combined modality treatment. Studies were initiated to determine whether busulfan, an alkylating agent known to produce aplastic anemia, would cause microenvironmental damage similar to that seen following cyclophosphamide. The mice received intraperitoneal doses of busulfan one week after 1500 rad leg irradation. In general, the pattern of hemopoietic suppression was similar to that following sequential radiation and cyclophosphamide. However, at 4 and 6 months post-irradiation, the busulfan treated mice had a more severe suppression of CFU-S, CFU-C, and marrow stromal cells than mice treated with cyclophosphamide alone. In addition, an excessive number of myeloid blast cells and a severe erythroid depletion suggested that the BU-treated mice were preleukemic. Vascular patency was studied by injecting 51 Cr labeled autologous red blood cells into mice treated with the radiation and busulfan regimen. Combined modality therapy inhibited the ingress of 51 Cr labeled erythrocytes into the irradiated femur but either modality alone did not cause inhibition. It was concluded that a portion of the microenvironmental defect seen in the combined radiation and alkylating agent studies was the result of microvascular damage and that a portion was due to marrow stromal cell insufficiency

Aag DNA glycosylase promotes alkylation-induced tissue damage mediated by Parp1.

Science.gov (United States)

Calvo, Jennifer A; Moroski-Erkul, Catherine A; Lake, Annabelle; Eichinger, Lindsey W; Shah, Dharini; Jhun, Iny; Limsirichai, Prajit; Bronson, Roderick T; Christiani, David C; Meira, Lisiane B; Samson, Leona D

2013-04-01

Alkylating agents comprise a major class of front-line cancer chemotherapeutic compounds, and while these agents effectively kill tumor cells, they also damage healthy tissues. Although base excision repair (BER) is essential in repairing DNA alkylation damage, under certain conditions, initiation of BER can be detrimental. Here we illustrate that the alkyladenine DNA glycosylase (AAG) mediates alkylation-induced tissue damage and whole-animal lethality following exposure to alkylating agents. Aag-dependent tissue damage, as observed in cerebellar granule cells, splenocytes, thymocytes, bone marrow cells, pancreatic β-cells, and retinal photoreceptor cells, was detected in wild-type mice, exacerbated in Aag transgenic mice, and completely suppressed in Aag⁻/⁻ mice. Additional genetic experiments dissected the effects of modulating both BER and Parp1 on alkylation sensitivity in mice and determined that Aag acts upstream of Parp1 in alkylation-induced tissue damage; in fact, cytotoxicity in WT and Aag transgenic mice was abrogated in the absence of Parp1. These results provide in vivo evidence that Aag-initiated BER may play a critical role in determining the side-effects of alkylating agent chemotherapies and that Parp1 plays a crucial role in Aag-mediated tissue damage.

Aag DNA glycosylase promotes alkylation-induced tissue damage mediated by Parp1.

Directory of Open Access Journals (Sweden)

Jennifer A Calvo

2013-04-01

Full Text Available Alkylating agents comprise a major class of front-line cancer chemotherapeutic compounds, and while these agents effectively kill tumor cells, they also damage healthy tissues. Although base excision repair (BER is essential in repairing DNA alkylation damage, under certain conditions, initiation of BER can be detrimental. Here we illustrate that the alkyladenine DNA glycosylase (AAG mediates alkylation-induced tissue damage and whole-animal lethality following exposure to alkylating agents. Aag-dependent tissue damage, as observed in cerebellar granule cells, splenocytes, thymocytes, bone marrow cells, pancreatic β-cells, and retinal photoreceptor cells, was detected in wild-type mice, exacerbated in Aag transgenic mice, and completely suppressed in Aag⁻/⁻ mice. Additional genetic experiments dissected the effects of modulating both BER and Parp1 on alkylation sensitivity in mice and determined that Aag acts upstream of Parp1 in alkylation-induced tissue damage; in fact, cytotoxicity in WT and Aag transgenic mice was abrogated in the absence of Parp1. These results provide in vivo evidence that Aag-initiated BER may play a critical role in determining the side-effects of alkylating agent chemotherapies and that Parp1 plays a crucial role in Aag-mediated tissue damage.

Molecular characterization of an adaptive response to alkylating agents in the opportunistic pathogen Aspergillus fumigatus.

Science.gov (United States)

O'Hanlon, Karen A; Margison, Geoffrey P; Hatch, Amy; Fitzpatrick, David A; Owens, Rebecca A; Doyle, Sean; Jones, Gary W

2012-09-01

An adaptive response to alkylating agents based upon the conformational change of a methylphosphotriester (MPT) DNA repair protein to a transcriptional activator has been demonstrated in a number of bacterial species, but this mechanism appears largely absent from eukaryotes. Here, we demonstrate that the human pathogen Aspergillus fumigatus elicits an adaptive response to sub-lethal doses of the mono-functional alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). We have identified genes that encode MPT and O(6)-alkylguanine DNA alkyltransferase (AGT) DNA repair proteins; deletions of either of these genes abolish the adaptive response and sensitize the organism to MNNG. In vitro DNA repair assays confirm the ability of MPT and AGT to repair methylphosphotriester and O(6)-methylguanine lesions respectively. In eukaryotes, the MPT protein is confined to a select group of fungal species, some of which are major mammalian and plant pathogens. The evolutionary origin of the adaptive response is bacterial and rooted within the Firmicutes phylum. Inter-kingdom horizontal gene transfer between Firmicutes and Ascomycete ancestors introduced the adaptive response into the Fungal kingdom. Our data constitute the first detailed characterization of the molecular mechanism of the adaptive response in a lower eukaryote and has applications for development of novel fungal therapeutics targeting this DNA repair system.

Molecular characterization of an adaptive response to alkylating agents in the opportunistic pathogen Aspergillus fumigatus

Science.gov (United States)

O’Hanlon, Karen A.; Margison, Geoffrey P.; Hatch, Amy; Fitzpatrick, David A.; Owens, Rebecca A.; Doyle, Sean; Jones, Gary W.

2012-01-01

An adaptive response to alkylating agents based upon the conformational change of a methylphosphotriester (MPT) DNA repair protein to a transcriptional activator has been demonstrated in a number of bacterial species, but this mechanism appears largely absent from eukaryotes. Here, we demonstrate that the human pathogen Aspergillus fumigatus elicits an adaptive response to sub-lethal doses of the mono-functional alkylating agent N-methyl-N′-nitro-N-nitrosoguanidine (MNNG). We have identified genes that encode MPT and O6-alkylguanine DNA alkyltransferase (AGT) DNA repair proteins; deletions of either of these genes abolish the adaptive response and sensitize the organism to MNNG. In vitro DNA repair assays confirm the ability of MPT and AGT to repair methylphosphotriester and O6-methylguanine lesions respectively. In eukaryotes, the MPT protein is confined to a select group of fungal species, some of which are major mammalian and plant pathogens. The evolutionary origin of the adaptive response is bacterial and rooted within the Firmicutes phylum. Inter-kingdom horizontal gene transfer between Firmicutes and Ascomycete ancestors introduced the adaptive response into the Fungal kingdom. Our data constitute the first detailed characterization of the molecular mechanism of the adaptive response in a lower eukaryote and has applications for development of novel fungal therapeutics targeting this DNA repair system. PMID:22669901

Hybrid ligand-alkylating agents targeting telomeric G-quadruplex structures.

Science.gov (United States)

Doria, Filippo; Nadai, Matteo; Folini, Marco; Di Antonio, Marco; Germani, Luca; Percivalle, Claudia; Sissi, Claudia; Zaffaroni, Nadia; Alcaro, Stefano; Artese, Anna; Richter, Sara N; Freccero, Mauro

2012-04-14

The synthesis, physico-chemical properties and biological effects of a new class of naphthalene diimides (NDIs) capable of reversibly binding telomeric DNA and alkylate it through an electrophilic quinone methide moiety (QM), are reported. FRET and circular dichroism assays showed a marked stabilization and selectivity towards telomeric G4 DNA folded in a hybrid topology. NDI-QMs' alkylating properties revealed a good reactivity on single nucleosides and selectivity towards telomeric G4. A selected NDI was able to significantly impair the growth of melanoma cells by causing telomere dysfunction and down-regulation of telomerase expression. These findings points to our hybrid ligand-alkylating NDIs as possible tools for the development of novel targeted anticancer therapies. This journal is © The Royal Society of Chemistry 2012

N-methylpurine DNA glycosylase inhibits p53-mediated cell cycle arrest and coordinates with p53 to determine sensitivity to alkylating agents.

Science.gov (United States)

Song, Shanshan; Xing, Guichun; Yuan, Lin; Wang, Jian; Wang, Shan; Yin, Yuxin; Tian, Chunyan; He, Fuchu; Zhang, Lingqiang

2012-08-01

Alkylating agents induce genome-wide base damage, which is repaired mainly by N-methylpurine DNA glycosylase (MPG). An elevated expression of MPG in certain types of tumor cells confers higher sensitivity to alkylation agents because MPG-induced apurinic/apyrimidic (AP) sites trigger more strand breaks. However, the determinant of drug sensitivity or insensitivity still remains unclear. Here, we report that the p53 status coordinates with MPG to play a pivotal role in such process. MPG expression is positive in breast, lung and colon cancers (38.7%, 43.4% and 25.3%, respectively) but negative in all adjacent normal tissues. MPG directly binds to the tumor suppressor p53 and represses p53 activity in unstressed cells. The overexpression of MPG reduced, whereas depletion of MPG increased, the expression levels of pro-arrest gene downstream of p53 including p21, 14-3-3σ and Gadd45 but not proapoptotic ones. The N-terminal region of MPG was specifically required for the interaction with the DNA binding domain of p53. Upon DNA alkylation stress, in p53 wild-type tumor cells, p53 dissociated from MPG and induced cell growth arrest. Then, AP sites were repaired efficiently, which led to insensitivity to alkylating agents. By contrast, in p53-mutated cells, the AP sites were repaired with low efficacy. To our knowledge, this is the first direct evidence to show that a DNA repair enzyme functions as a selective regulator of p53, and these findings provide new insights into the functional linkage between MPG and p53 in cancer therapy.

Ocular Toxicity Profile of ST-162 and ST-168 as Novel Bifunctional MEK/PI3K Inhibitors.

Science.gov (United States)

Smith, Andrew; Pawar, Mercy; Van Dort, Marcian E; Galbán, Stefanie; Welton, Amanda R; Thurber, Greg M; Ross, Brian D; Besirli, Cagri G

2018-04-30

ST-162 and ST-168 are small-molecule bifunctional inhibitors of MEK and PI3K signaling pathways that are being developed as novel antitumor agents. Previous small-molecule and biologic MEK inhibitors demonstrated ocular toxicity events that were dose limiting in clinical studies. We evaluated in vitro and in vivo ocular toxicity profiles of ST-162 and ST-168. Photoreceptor cell line 661W and adult retinal pigment epithelium cell line ARPE-19 were treated with increasing concentrations of bifunctional inhibitors. Western blots, cell viability, and caspase activity assays were performed to evaluate MEK and PI3K inhibition and dose-dependent in vitro toxicity, and compared with monotherapy. In vivo toxicity profile was assessed by intravitreal injection of ST-162 and ST-168 in Dutch-Belted rabbits, followed by ocular examination and histological analysis of enucleated eyes. Retinal cell lines treated with ST-162 or ST-168 exhibited dose-dependent inhibition of MEK and PI3K signaling. Compared with inhibition by monotherapies and their combinations, bifunctional inhibitors demonstrated reduced cell death and caspase activity. In vivo, both bifunctional inhibitors exhibited a more favorable toxicity profile when compared with MEK inhibitor PD0325901. Novel MEK and PI3K bifunctional inhibitors ST-162 and ST-168 demonstrate favorable in vitro and in vivo ocular toxicity profiles, supporting their further development as potential therapeutic agents targeting multiple aggressive tumors.

Synthesis and Characterization of Bifunctional Organic-Glasses Based on Diphenylhydrazone and Barbituric Acid Derivative for Photorefractive Application

Energy Technology Data Exchange (ETDEWEB)

Park, Ki Hong [KIST, Seoul (Korea, Republic of); Lee, Sang Ho; Choi, Chil Sung; Kim, Nak Joong [Hanyang University, Seoul (Korea, Republic of); Choi, Dong Hoon [Kyunghee University, Youngin (Korea, Republic of)

2003-12-15

A series of amorphous molecules that possess both photoconductive and electro-optic properties was synthesized in order to investigate photorefractive properties of bifunctional organic-glasses. Diethylaminobenzaldehyde- diphenylhydrazone was covalently attached to 5-(4-diethylamino-benzylidene)-1,3-dimethylpyrimidine- 2,4,6-trione through a flexible alkyl chain (3, 4, 5, 6 and 10 carbons) containing two ether linkages. The longer linkage not only lowered the glass transition temperature (Tg) of the molecules, but also allowed faster orientation of the chromophore. To examine the photorefractive properties, a 50 μm-thick film was prepared from the mixture of a bifunctional molecule, butyl benzyl phthalate, and C{sup 60}. The photoconductivity of this composite was as high as 8.01 x 10{sup -12} S/cm at 60 V/μm, and the maximum diffraction efficiency (ηmax) of 50 μm-thick film was about 5% at 80 V/μm.

Alkylation damage causes MMR-dependent chromosomal instability in vertebrate embryos.

NARCIS (Netherlands)

Feitsma, H.; Akay, A.; Cuppen, E.

2008-01-01

S(N)1-type alkylating agents, like N-methyl-N-nitrosourea (MNU) and N-ethyl-N-nitrosourea (ENU), are potent mutagens. Exposure to alkylating agents gives rise to O(6)-alkylguanine, a modified base that is recognized by DNA mismatch repair (MMR) proteins but is not repairable, resulting in

Targeting the plasma membrane of neoplastic cells through alkylation: a novel approach to cancer chemotherapy.

Science.gov (United States)

Trendowski, Matthew; Fondy, Thomas P

2015-08-01

Although DNA-directed alkylating agents and related compounds have been a mainstay in chemotherapeutic protocols due to their ability to readily interfere with the rapid mitotic progression of malignant cells, their clinical utility is limited by DNA repair mechanisms and immunosuppression. However, the same destructive nature of alkylation can be reciprocated at the cell surface using novel plasma membrane alkylating agents. Plasma membrane alkylating agents have elicited long term survival in mammalian models challenged with carcinomas, sarcomas, and leukemias. Further, a specialized group of plasma membrane alkylating agents known as tetra-O-acetate haloacetamido carbohydrate analogs (Tet-OAHCs) potentiates a substantial leukocyte influx at the administration and primary tumor site, indicative of a potent immune response. The effects of plasma membrane alkylating agents may be further potentiated through the use of another novel class of chemotherapeutic agents, known as dihydroxyacetone phosphate (DHAP) inhibitors, since many cancer types are known to rely on the DHAP pathway for lipid synthesis. Despite these compelling data, preliminary clinical trials for plasma membrane-directed agents have yet to be considered. Therefore, this review is intended for academics and clinicians to postulate a novel approach of chemotherapy; altering critical malignant cell signaling at the plasma membrane surface through alkylation, thereby inducing irreversible changes to functions needed for cell survival.

Genomic patterns resembling BRCA1- and BRCA2-mutated breast cancers predict benefit of intensified carboplatin-based chemotherapy

NARCIS (Netherlands)

Vollebergh, Marieke A.; Lips, Esther H.; Nederlof, Petra M.; Wessels, Lodewyk F. A.; Wesseling, Jelle; Vijver, Marc J. vd; de Vries, Elisabeth G. E.; van Tinteren, Harm; Jonkers, Jos; Hauptmann, Michael; Rodenhuis, Sjoerd; Linn, Sabine C.

2014-01-01

Introduction: BRCA-mutated breast cancer cells lack the DNA-repair mechanism homologous recombination that is required for error-free DNA double-strand break (DSB) repair. Homologous recombination deficiency (HRD) may cause hypersensitivity to DNA DSB-inducing agents, such as bifunctional alkylating

Downregulation of hPMC2 imparts chemotherapeutic sensitivity to alkylating agents in breast cancer cells.

Science.gov (United States)

Krishnamurthy, Nirmala; Liu, Lili; Xiong, Xiahui; Zhang, Junran; Montano, Monica M

2015-01-01

Triple negative breast cancer cell lines have been reported to be resistant to the cyotoxic effects of temozolomide (TMZ). We have shown previously that a novel protein, human homolog of Xenopus gene which Prevents Mitotic Catastrophe (hPMC2) has a role in the repair of estrogen-induced abasic sites. Our present study provides evidence that downregulation of hPMC2 in MDA-MB-231 and MDA-MB-468 breast cancer cells treated with temozolomide (TMZ) decreases cell survival. This increased sensitivity to TMZ is associated with an increase in number of apurinic/apyrimidinic (AP) sites in the DNA. We also show that treatment with another alkylating agent, BCNU, results in an increase in AP sites and decrease in cell survival. Quantification of western blot analyses and immunofluorescence experiments reveal that treatment of hPMC2 downregulated cells with TMZ results in an increase in γ-H2AX levels, suggesting an increase in double strand DNA breaks. The enhancement of DNA double strand breaks in TMZ treated cells upon downregulation of hPCM2 is also revealed by the comet assay. Overall, we provide evidence that downregulation of hPMC2 in breast cancer cells increases cytotoxicity of alkylating agents, representing a novel mechanism of treatment for breast cancer. Our data thus has important clinical implications in the management of breast cancer and brings forth potentially new therapeutic strategies.

Overexpressed human metallothionein IIA gene protects Chinese hamster ovary cells from killing by alkylating agents

International Nuclear Information System (INIS)

Kaina, B.; Lohrer, H.; Karin, M.; Herrlich, P.

1990-01-01

Experiments were designed to detect survival advantages that cells gain by overexpressing metallothionein (MT). Chinese hamster ovary K1-2 cells and an x-ray-sensitive derivative were transfected with a bovine papillomavirus (BPV)-linked construct carrying the human metallothionein IIA (hMT-IIA) gene. Transfectants survived 40-fold higher levels of cadmium chloride, harbored at least 30 copies of hMT-IIA, and contained 25- to 166-fold more MT than the parent cells. Even under conditions of reduced glutathione synthesis, the transfectants were not more resistant to the lethal effects of ionizing radiation and bleomycin than the parent cells. Thus free radicals generated by these agents cannot be scavenged efficiently by MT in vivo. The hMT-IIA transfectants, however, but not control transfectants harboring a BPV-MT promoter-neo construct, tolerated significantly higher doses of the alkylating agents N-methyl-N-nitrosourea and N-methyl-N'-nitro-N-nitrosoguanidine. Resistance and MT overexpression occurred irrespective of selection and cultivation in cadmium and zinc. There was no increase in resistance to methyl methanesulfonate and N-hydroxyethyl-N-chloroethylnitrosourea. MT did not affect the degree of overall DNA methylation after N-methyl-N-nitrosourea treatment nor the level of O6-methylguanine-DNA methyltransferase. The results suggest that MT participates as a cofactor or regulatory element in repair or tolerance of toxic alkylation lesions

Overexpressed human metallothionein IIA gene protects Chinese hamster ovary cells from killing by alkylating agents

Energy Technology Data Exchange (ETDEWEB)

Kaina, B.; Lohrer, H.; Karin, M.; Herrlich, P. (Kernforschungszentrum Karlsruhe, Karlsruhe (Germany, F.R.))

1990-04-01

Experiments were designed to detect survival advantages that cells gain by overexpressing metallothionein (MT). Chinese hamster ovary K1-2 cells and an x-ray-sensitive derivative were transfected with a bovine papillomavirus (BPV)-linked construct carrying the human metallothionein IIA (hMT-IIA) gene. Transfectants survived 40-fold higher levels of cadmium chloride, harbored at least 30 copies of hMT-IIA, and contained 25- to 166-fold more MT than the parent cells. Even under conditions of reduced glutathione synthesis, the transfectants were not more resistant to the lethal effects of ionizing radiation and bleomycin than the parent cells. Thus free radicals generated by these agents cannot be scavenged efficiently by MT in vivo. The hMT-IIA transfectants, however, but not control transfectants harboring a BPV-MT promoter-neo construct, tolerated significantly higher doses of the alkylating agents N-methyl-N-nitrosourea and N-methyl-N'-nitro-N-nitrosoguanidine. Resistance and MT overexpression occurred irrespective of selection and cultivation in cadmium and zinc. There was no increase in resistance to methyl methanesulfonate and N-hydroxyethyl-N-chloroethylnitrosourea. MT did not affect the degree of overall DNA methylation after N-methyl-N-nitrosourea treatment nor the level of O6-methylguanine-DNA methyltransferase. The results suggest that MT participates as a cofactor or regulatory element in repair or tolerance of toxic alkylation lesions.

Overexpressed human metallothionein IIA gene protects Chinese hamster ovary cells from killing by alkylating agents.

Science.gov (United States)

Kaina, B; Lohrer, H; Karin, M; Herrlich, P

1990-01-01

Experiments were designed to detect survival advantages that cells gain by overexpressing metallothionein (MT). Chinese hamster ovary K1-2 cells and an x-ray-sensitive derivative were transfected with a bovine papillomavirus (BPV)-linked construct carrying the human metallothionein IIA (hMT-IIA) gene. Transfectants survived 40-fold higher levels of cadmium chloride, harbored at least 30 copies of hMT-IIA, and contained 25- to 166-fold more MT than the parent cells. Even under conditions of reduced glutathione synthesis, the transfectants were not more resistant to the lethal effects of ionizing radiation and bleomycin than the parent cells. Thus free radicals generated by these agents cannot be scavenged efficiently by MT in vivo. The hMT-IIA transfectants, however, but not control transfectants harboring a BPV-MT promoter-neo construct, tolerated significantly higher doses of the alkylating agents N-methyl-N-nitrosourea and N-methyl-N'-nitro-N-nitrosoguanidine. Resistance and MT overexpression occurred irrespective of selection and cultivation in cadmium and zinc. There was no increase in resistance to methyl methanesulfonate and N-hydroxyethyl-N-chloroethylnitrosourea. MT did not affect the degree of overall DNA methylation after N-methyl-N-nitrosourea treatment nor the level of O6-methylguanine-DNA methyltransferase. The results suggest that MT participates as a cofactor or regulatory element in repair or tolerance of toxic alkylation lesions. Images PMID:2320583

Overexpression of metallothionein in CHO cells and its effect on cell killing by ionizing radiation and alkylating agents

International Nuclear Information System (INIS)

Lohrer, H.; Robson, T.

1989-01-01

Metallothionein protein protects cells from the toxic effects of heavy metal ions. To establish its protective function against ionizing radiation and alkylating agents, a model system was created by transfecting two CHO cell lines (wild-type, K1-2 and X-ray sensitive, xrs-2 subclone Bc11) with the human metallothionein II-A (hMTII-A) gene integrated in a bovine papilloma derived autonomously replicating vector. The isolated transfectants are cadmium-resistant (Cd 1 ), due to the overexpression of the hMTII-A gene. Their steady-state level of hMTII-A mRNA can be increased up to 40-fold after Cd treatment and 20-fold after induction with ionizing radiation. The transfected cell lines proved to be as sensitive as the recipient cell lines to ionizing radiation and bleomycin but the transfectants were significantly more resistant to N-methyl-nitro-nitrosoguanidine (MNNG) and mitomycin C (MMC). These results lead to the conclusion that the MT protein does provide a defence mechanism to protect cells from monofunctional alkylating and cross-linking agents but not from free radicals. (author)

Overexpression of metallothionein in CHO cells and its effect on cell killing by ionizing radiation and alkylating agents

Energy Technology Data Exchange (ETDEWEB)

Lohrer, H.; Robson, T. (Newcastle upon Tyne Univ. (UK). Cancer Research Unit)

1989-12-01

Metallothionein protein protects cells from the toxic effects of heavy metal ions. To establish its protective function against ionizing radiation and alkylating agents, a model system was created by transfecting two CHO cell lines (wild-type, K1-2 and X-ray sensitive, xrs-2 subclone Bc11) with the human metallothionein II-A (hMTII-A) gene integrated in a bovine papilloma derived autonomously replicating vector. The isolated transfectants are cadmium-resistant (Cd{sup 1}), due to the overexpression of the hMTII-A gene. Their steady-state level of hMTII-A mRNA can be increased up to 40-fold after Cd treatment and 20-fold after induction with ionizing radiation. The transfected cell lines proved to be as sensitive as the recipient cell lines to ionizing radiation and bleomycin but the transfectants were significantly more resistant to N-methyl-nitro-nitrosoguanidine (MNNG) and mitomycin C (MMC). These results lead to the conclusion that the MT protein does provide a defence mechanism to protect cells from monofunctional alkylating and cross-linking agents but not from free radicals. (author).

Molecular signal for induction of the adaptive response to alkylating agents in E. coli

Energy Technology Data Exchange (ETDEWEB)

Lindahl, T.; Sedgwick, B.; Teo, I.; Kilpatrick, M.; McCarthy, T.; Hughes, S.

1986-05-01

Exposure of E. coli to simple alkylating agents such as methylnitrosourea causes the induction of at least three DNA repair functions, which are under the control of the ada gene. The intracellular signal for switching on the response has been identified as one of the two stereoisomers of methyl phosphotriesters generated in DNA by alkylation. The methyl group is transferred from the phosphotriester moiety to a specific cysteine residue within the regulatory Ada protein in a self-methylation reaction. This protein also corrects the mutagenic lesion O/sup 6/-methylguanine by transfer of its methyl group to a separate cysteine residue in the Ada protein. Methylation of the protein from repair of a DNA phosphotriester residue, but not from O/sup 6/-methylguanine, converts it to an activator of transcription of genes involved in the adaptive response. The activated form of the Ada protein enhances transcription by binding specifically to a sequence d(AAA--AAAGCGCA), located immediately upstream of the RNA polymerase binding site in relevant promoter regions.

Digital PCR quantification of MGMT methylation refines prediction of clinical benefit from alkylating agents in glioblastoma and metastatic colorectal cancer

NARCIS (Netherlands)

Barault, L.; Amatu, A.; Bleeker, F. E.; Moutinho, C.; Falcomatà, C.; Fiano, V.; Cassingena, A.; Siravegna, G.; Milione, M.; Cassoni, P.; de Braud, F.; Rudà, R.; Soffietti, R.; Venesio, T.; Bardelli, A.; Wesseling, P.; de Witt Hamer, P.; Pietrantonio, F.; Siena, S.; Esteller, M.; Sartore-Bianchi, A.; Di Nicolantonio, F.

2015-01-01

O(6)-methyl-guanine-methyl-transferase (MGMT) silencing by promoter methylation may identify cancer patients responding to the alkylating agents dacarbazine or temozolomide. We evaluated the prognostic and predictive value of MGMT methylation testing both in tumor and cell-free circulating DNA

Digital PCR quantification of MGMT methylation refines prediction of clinical benefit from alkylating agents in glioblastoma and metastatic colorectal cancer

NARCIS (Netherlands)

Barault, L.; Amatu, A.; Bleeker, F. E.; Moutinho, C.; Falcomatà, C.; Fiano, V.; Cassingena, A.; Siravegna, G.; Milione, M.; Cassoni, P.; de Braud, F.; Rudà, R.; Soffietti, R.; Venesio, T.; Bardelli, A.; Wesseling, P.; de Witt Hamer, P.; Pietrantonio, F.; Siena, S.; Esteller, M.; Sartore-Bianchi, A.; di Nicolantonio, Federica

2015-01-01

Background: O6-methyl-guanine-methyl-transferase (MGMT) silencing by promoter methylation may identify cancer patients responding to the alkylating agents dacarbazine or temozolomide. Patients and methods: We evaluated the prognostic and predictive value of MGMT methylation testing both in tumor and

Effect of radiation and alkylating agents on chromatin degradation in normal and malignant lymphoid cells

International Nuclear Information System (INIS)

Ryabchenko, N.I.; Yurashkova, V.; Ivannik, B.P.; Konov, A.V.; Drashil, V.

1991-01-01

Regularities of chromatin degradation in thymocytes and LS/BL tumor cells have been investigated. It has been shown that the rate of DNA degradation by Ca/Mg-dependent endonuclease in LS/BL tumor cells is 25 times lower than that in thymocytes, and radiation does not induce chormatin degradation. The alkylating agent TS 160 causes chromatin degradation in both LS/Bl cells and thymocytes. In contrast to radiation TS 160 inhibits the endogenous chromatin degradation by Ca/Mg-dependent endonuclease in thymocytes

The cyclophosphamide equivalent dose as an approach for quantifying alkylating agent exposure: a report from the Childhood Cancer Survivor Study.

Science.gov (United States)

Green, Daniel M; Nolan, Vikki G; Goodman, Pamela J; Whitton, John A; Srivastava, DeoKumar; Leisenring, Wendy M; Neglia, Joseph P; Sklar, Charles A; Kaste, Sue C; Hudson, Melissa M; Diller, Lisa R; Stovall, Marilyn; Donaldson, Sarah S; Robison, Leslie L

2014-01-01

Estimation of the risk of adverse long-term outcomes such as second malignant neoplasms and infertility often requires reproducible quantification of exposures. The method for quantification should be easily utilized and valid across different study populations. The widely used Alkylating Agent Dose (AAD) score is derived from the drug dose distribution of the study population and thus cannot be used for comparisons across populations as each will have a unique distribution of drug doses. We compared the performance of the Cyclophosphamide Equivalent Dose (CED), a unit for quantifying alkylating agent exposure independent of study population, to the AAD. Comparisons included associations from three Childhood Cancer Survivor Study (CCSS) outcome analyses, receiver operator characteristic (ROC) curves and goodness of fit based on the Akaike's Information Criterion (AIC). The CED and AAD performed essentially identically in analyses of risk for pregnancy among the partners of male CCSS participants, risk for adverse dental outcomes among all CCSS participants and risk for premature menopause among female CCSS participants, based on similar associations, lack of statistically significant differences between the areas under the ROC curves and similar model fit values for the AIC between models including the two measures of exposure. The CED is easily calculated, facilitating its use for patient counseling. It is independent of the drug dose distribution of a particular patient population, a characteristic that will allow direct comparisons of outcomes among epidemiological cohorts. We recommend the use of the CED in future research assessing cumulative alkylating agent exposure. © 2013 Wiley Periodicals, Inc.

Down-regulation of DNA mismatch repair proteins in human and murine tumor spheroids: implications for multicellular resistance to alkylating agents.

Science.gov (United States)

Francia, Giulio; Green, Shane K; Bocci, Guido; Man, Shan; Emmenegger, Urban; Ebos, John M L; Weinerman, Adina; Shaked, Yuval; Kerbel, Robert S

2005-10-01

Similar to other anticancer agents, intrinsic or acquired resistance to DNA-damaging chemotherapeutics is a major obstacle for cancer therapy. Current strategies aimed at overcoming this problem are mostly based on the premise that tumor cells acquire heritable genetic mutations that contribute to drug resistance. Here, we present evidence for an epigenetic, tumor cell adhesion-mediated, and reversible form of drug resistance that is associated with a reduction of DNA mismatch repair proteins PMS2 and/or MLH1 as well as other members of this DNA repair process. Growth of human breast cancer, human melanoma, and murine EMT-6 breast cancer cell lines as multicellular spheroids in vitro, which is associated with increased resistance to many chemotherapeutic drugs, including alkylating agents, is shown to lead to a reproducible down-regulation of PMS2, MLH1, or, in some cases, both as well as MHS6, MSH3, and MSH2. The observed down-regulation is in part reversible by treatment of tumor spheroids with the DNA-demethylating agent, 5-azacytidine. Thus, treatment of EMT-6 mouse mammary carcinoma spheroids with 5-azacytidine resulted in reduced and/or disrupted cell-cell adhesion, which in turn sensitized tumor spheroids to cisplatin-mediated killing in vitro. Our results suggest that antiadhesive agents might sensitize tumor spheroids to alkylating agents in part by reversing or preventing reduced DNA mismatch repair activity and that the chemosensitization properties of 5-azacytidine may conceivably reflect its role as a potential antiadhesive agent as well as reversal agent for MLH1 gene silencing in human tumors.

PARP inhibitors protect against sex- and AAG-dependent alkylation-induced neural degeneration.

Science.gov (United States)

Allocca, Mariacarmela; Corrigan, Joshua J; Fake, Kimberly R; Calvo, Jennifer A; Samson, Leona D

2017-09-15

Alkylating agents are commonly used to treat cancer. Although base excision repair (BER) is a major pathway for repairing DNA alkylation damage, under certain conditions, the initiation of BER produces toxic repair intermediates that damage healthy tissues. The initiation of BER by the alkyladenine DNA glycosylase (AAG, a.k.a. MPG) can mediate alkylation-induced cytotoxicity in specific cells in the retina and cerebellum of male mice. Cytotoxicity in both wild-type and Aag -transgenic ( AagTg ) mice is abrogated in the absence of Poly(ADP-ribose) polymerase-1 (PARP1). Here, we tested whether PARP inhibitors can also prevent alkylation-induced retinal and cerebellar degeneration in male and female WT and AagTg mice. Importantly, we found that WT mice display sex-dependent alkylation-induced retinal damage (but not cerebellar damage), with WT males being more sensitive than females. Accordingly, estradiol treatment protects males against alkylation-induced retinal degeneration. In AagTg male and female mice, the alkylation-induced tissue damage in both the retina and cerebellum is exacerbated and the sex difference in the retina is abolished. PARP inhibitors, much like Parp1 gene deletion, protect against alkylation-induced AAG-dependent neuronal degeneration in WT and AagTg mice, regardless of the gender, but their efficacy in preventing alkylation-induced neuronal degeneration depends on PARP inhibitor characteristics and doses. The recent surge in the use of PARP inhibitors in combination with cancer chemotherapeutic alkylating agents might represent a powerful tool for obtaining increased therapeutic efficacy while avoiding the collateral effects of alkylating agents in healthy tissues.

Use of 2-mercaptopyridine for the determination of alkylating agents in complex matrices: application to dimethyl sulfate.

Science.gov (United States)

Hoogerheide, J G; Scott, R A

2005-01-30

A rapid and sensitive method for the determination of alkylating agents in complex reaction mixtures was developed and characterized. Analyses are based on the alkylation of 2-mercaptopyridine by the analyte; the derivative is separated by RP-HPLC and measured by fluorescence detection. When applied to the determination of dimethyl sulfate, the method is linear over four orders of magnitude: 0.01-10mugmL(-1). By using recrystallized 2-mercaptopyridine, quantitation limits of 10ngmL(-1) can be achieved. Precision of the assay is 2% R.S.D. in the 1-10mugmL(-1) range and about 15% R.S.D. at 10ngmL(-1). Studies on the pH dependence of the derivatization reaction were key to minimizing interference from the dimethyl sulfate degradation product, monomethyl sulfate, in quenched reaction samples.

Influence of promoter/enhancer region haplotypes on MGMT transcriptional regulation: a potential biomarker for human sensitivity to alkylating agents.

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Xu, Meixiang; Nekhayeva, Ilona; Cross, Courtney E; Rondelli, Catherine M; Wickliffe, Jeffrey K; Abdel-Rahman, Sherif Z

2014-03-01

The O6-methylguanine-DNA methyltransferase gene (MGMT) encodes the direct reversal DNA repair protein that removes alkyl adducts from the O6 position of guanine. Several single-nucleotide polymorphisms (SNPs) exist in the MGMT promoter/enhancer (P/E) region. However, the haplotype structure encompassing these SNPs and their functional/biological significance are currently unknown. We hypothesized that MGMT P/E haplotypes, rather than individual SNPs, alter MGMT transcription and can thus alter human sensitivity to alkylating agents. To identify the haplotype structure encompassing the MGMT P/E region SNPs, we sequenced 104 DNA samples from healthy individuals and inferred the haplotypes using the data generated. We identified eight SNPs in this region, namely T7C (rs180989103), T135G (rs1711646), G290A (rs61859810), C485A (rs1625649), C575A (rs113813075), G666A (rs34180180), C777A (rs34138162) and C1099T (rs16906252). Phylogenetics and Sequence Evolution analysis predicted 21 potential haplotypes that encompass these SNPs ranging in frequencies from 0.000048 to 0.39. Of these, 10 were identified in our study population as 20 paired haplotype combinations. To determine the functional significance of these haplotypes, luciferase reporter constructs representing these haplotypes were transfected into glioblastoma cells and their effect on MGMT promoter activity was determined. Compared with the most common (reference) haplotype 1, seven haplotypes significantly upregulated MGMT promoter activity (18-119% increase; P alkylating agents.

Alkylation of N-substituted 2-phenylacetamides

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SLOBODAN D. PETROVIC

2004-10-01

Full Text Available Various N-substituted phenylacetamides were alkylated using different alkylating agents under neutral and basic conditions. Reactions were performed at different reaction temperatures and in various solvents. Also, a number of various catalysts were used including phase-transfer catalysts. Reactions were followed using GC or GC-MS technique and the presence as well as the yields of the alkylation products were established. Generally, the best yield and high selectivity in the studied reactions were achieved under basic conditions where in the certain cases some products, mostly N-product, were obtained solely in quantitative yields.

2-Sulfonylpyrimidines: Mild alkylating agents with anticancer activity toward p53-compromised cells.

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Bauer, Matthias R; Joerger, Andreas C; Fersht, Alan R

2016-09-06

The tumor suppressor p53 has the most frequently mutated gene in human cancers. Many of p53's oncogenic mutants are just destabilized and rapidly aggregate, and are targets for stabilization by drugs. We found certain 2-sulfonylpyrimidines, including one named PK11007, to be mild thiol alkylators with anticancer activity in several cell lines, especially those with mutationally compromised p53. PK11007 acted by two routes: p53 dependent and p53 independent. PK11007 stabilized p53 in vitro via selective alkylation of two surface-exposed cysteines without compromising its DNA binding activity. Unstable p53 was reactivated by PK11007 in some cancer cell lines, leading to up-regulation of p53 target genes such as p21 and PUMA. More generally, there was cell death that was independent of p53 but dependent on glutathione depletion and associated with highly elevated levels of reactive oxygen species and induction of endoplasmic reticulum (ER) stress, as also found for the anticancer agent PRIMA-1(MET)(APR-246). PK11007 may be a lead for anticancer drugs that target cells with nonfunctional p53 or impaired reactive oxygen species (ROS) detoxification in a wide variety of mutant p53 cells.

PML expression in soft tissue sarcoma: prognostic and predictive value in alkylating agents/antracycline-based first line therapy.

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Vincenzi, Bruno; Santini, Daniele; Schiavon, Gaia; Frezza, Anna Maria; Silletta, Marianna; Crucitti, Pierfilippo; Casali, Paolo; Dei Tos, Angelo P; Rossi, Sabrina; Rizzo, Sergio; Badalamenti, Giuseppe; Tomasino, Rosa Maria; Russo, Antonio; Butrynski, James E; Tonini, Giuseppe

2012-04-01

Soft tissue sarcomas are aggressive tumors representing alkylating agents/antracycline-based first line therapy. One hundred eleven patients affected by locally advanced and metastatic soft tissue sarcoma were selected. PML expression was evaluated by immunohistochemical analysis in pathological samples and in the corresponding normal tissue from each case. PML immunohistochemical results were correlated with prognosis and with radiological response to alkylating agents/antracycline-based first line therapy. PML expression was significantly reduced in synovial sarcomas (P < 0.0001), in myofibroblastic sarcomas (P < 0.0001), angiosarcomas (P < 0.0001), in leiomyosarcomas (P = 0.003), in mixoid liposarcomas (P < 0.0001), and in dedifferentiated liposarcomas (P < 0.0001). No significant difference was found for pleomorphic sarcoma [31.8 (95% CI: 16.7-41.0); P = 0.21]. and pleomorphic liposarcomas (P = 0.51). Loss of PML expression was found to be statistically correlated with TTP (P < 0.0001), median duration of response (P = 0.007), and OS (P = 0.02). No correlation was observed between PML expression and treatment efficacy. PML IHC expression is down-regulated in synovial sarcomas, myofibroblastic sarcomas, angiosarcomas, liposarcoma, and leiomyosarcomas and its expression correlated with prognosis. Copyright © 2011 Wiley Periodicals, Inc.

Synthesis and Characterization of Alkylated Bacterial Cellulose in an Ionic Liquid

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Jinmin Qin

2015-02-01

Full Text Available Bacterial cellulose was alkylated by alkyl halide in the ionic liquid 1-butyl-3-methylimmidazolium chloride ([Bmim]Cl with NaH as the alkaline agent. The derivatives were characterized using Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, elemental analyses, X-ray diffraction, and thermal gravimetric analyses. The resultant bacterial cellulose alkylated derivatives (BCADs had a degree of substitution (DS between 0.21 and 2.01. The effects of the alkylating agent, reactant amount, and temperature on the DS were investigated. BCADs with a butyl substituent had a higher DS than did those with ethyl or propyl groups. The crystallinity and thermal stability of the derivatives decreased after modification owing to the change in morphological structure.

Alkylation of hydrothiophosphoryl compounds in conditions of interphase catalysis

International Nuclear Information System (INIS)

Aladzheva, I.M.; Odinets, I.L.; Petrovskij, P.V.; Mastryukova, T.A.; Kabachkin, M.I.

1993-01-01

A method of interphase catalysis permitted to develop a common method for synthesis of compounds with thiophosphoryl group. The effect of nature of hydrothiophosphoryl compound, alkylating agent, two-phase system and reaction conditions on alkylation product yields was investigated in detail

Protonation of 1-alkyl-2-allyllithium-0-carboranes and 1-methyl-2-allylmaonesium chloride-0-carborane

International Nuclear Information System (INIS)

Ivanova, N.N.; Kazantsev, A.V.; Zakharkin, L.I.

1975-01-01

The ratio of 1-alkyl-2-allyl and 1-alkyl-2-propenyl-0-carboranes generated in protonation of 1-alkyl-2-lithium allyl-0-carboranes with various protolytic agents in ether, THF and liquid ammonia depends on the nature of protolytic agent and solvent. The rat:o of these allyl and propenyl isomers is also affected by steric effects of the protolytic agent and 0-carborane nucleus

A Theoretical Study of the Mechanism of the Alkylation of Guanine by N- Nitroso Compounds.

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1992-01-01

these chemical agents alkylate DNA, but, as yet, the precise mechanism is unknown. What is known is that the result is a DNA-mutagen adduct with an alkyl ... nitrosoureas , Singer et. al. found that about 25% of the alkylation caused by MNU was on the DNA phospate backbone while, for ENU, phosphate...sites. 1.3 Mutagenicity of N-Nitroso Compounds In early experimental work with agents which alkylate DNA, comparisons of ultraviolet absorption

Regulation of DNA Alkylation Damage Repair: Lessons and Therapeutic Opportunities.

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Soll, Jennifer M; Sobol, Robert W; Mosammaparast, Nima

2017-03-01

Alkylation chemotherapy is one of the most widely used systemic therapies for cancer. While somewhat effective, clinical responses and toxicities of these agents are highly variable. A major contributing factor for this variability is the numerous distinct lesions that are created upon alkylation damage. These adducts activate multiple repair pathways. There is mounting evidence that the individual pathways function cooperatively, suggesting that coordinated regulation of alkylation repair is critical to prevent toxicity. Furthermore, some alkylating agents produce adducts that overlap with newly discovered methylation marks, making it difficult to distinguish between bona fide damaged bases and so-called 'epigenetic' adducts. Here, we discuss new efforts aimed at deciphering the mechanisms that regulate these repair pathways, emphasizing their implications for cancer chemotherapy. Copyright © 2016 Elsevier Ltd. All rights reserved.

When alcohol is the answer: Trapping, identifying and quantifying simple alkylating species in aqueous environments.

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Penketh, Philip G; Shyam, Krishnamurthy; Baumann, Raymond P; Zhu, Rui; Ishiguro, Kimiko; Sartorelli, Alan C; Ratner, Elena S

2016-09-01

Alkylating agents are a significant class of environmental carcinogens as well as commonly used anticancer therapeutics. Traditional alkylating activity assays have utilized the colorimetric reagent 4-(4-nitrobenzyl)pyridine (4NBP). However, 4NBP based assays have a relatively low sensitivity towards harder, more oxophilic alkylating species and are not well suited for the identification of the trapped alkyl moiety due to adduct instability. Herein we describe a method using water as the trapping agent which permits the trapping of simple alkylating electrophiles with a comparatively wide range of softness/hardness and permits the identification of donated simple alkyl moieties. Copyright © 2016 Elsevier Inc. All rights reserved.

Small molecule inhibitors of ERCC1-XPF protein-protein interaction synergize alkylating agents in cancer cells.

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Jordheim, Lars Petter; Barakat, Khaled H; Heinrich-Balard, Laurence; Matera, Eva-Laure; Cros-Perrial, Emeline; Bouledrak, Karima; El Sabeh, Rana; Perez-Pineiro, Rolando; Wishart, David S; Cohen, Richard; Tuszynski, Jack; Dumontet, Charles

2013-07-01

The benefit of cancer chemotherapy based on alkylating agents is limited because of the action of DNA repair enzymes, which mitigate the damage induced by these agents. The interaction between the proteins ERCC1 and XPF involves two major components of the nucleotide excision repair pathway. Here, novel inhibitors of this interaction were identified by virtual screening based on available structures with use of the National Cancer Institute diversity set and a panel of DrugBank small molecules. Subsequently, experimental validation of the in silico screening was undertaken. Top hits were evaluated on A549 and HCT116 cancer cells. In particular, the compound labeled NSC 130813 [4-[(6-chloro-2-methoxy-9-acridinyl)amino]-2-[(4-methyl-1-piperazinyl)methyl

Mitochondrial targeting of human O6-methylguanine DNA methyltransferase protects against cell killing by chemotherapeutic alkylating agents.

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Cai, Shanbao; Xu, Yi; Cooper, Ryan J; Ferkowicz, Michael J; Hartwell, Jennifer R; Pollok, Karen E; Kelley, Mark R

2005-04-15

DNA repair capacity of eukaryotic cells has been studied extensively in recent years. Mammalian cells have been engineered to overexpress recombinant nuclear DNA repair proteins from ectopic genes to assess the impact of increased DNA repair capacity on genome stability. This approach has been used in this study to specifically target O(6)-methylguanine DNA methyltransferase (MGMT) to the mitochondria and examine its impact on cell survival after exposure to DNA alkylating agents. Survival of human hematopoietic cell lines and primary hematopoietic CD34(+) committed progenitor cells was monitored because the baseline repair capacity for alkylation-induced DNA damage is typically low due to insufficient expression of MGMT. Increased DNA repair capacity was observed when K562 cells were transfected with nuclear-targeted MGMT (nucl-MGMT) or mitochondrial-targeted MGMT (mito-MGMT). Furthermore, overexpression of mito-MGMT provided greater resistance to cell killing by 1,3-bis (2-chloroethyl)-1-nitrosourea (BCNU) than overexpression of nucl-MGMT. Simultaneous overexpression of mito-MGMT and nucl-MGMT did not enhance the resistance provided by mito-MGMT alone. Overexpression of either mito-MGMT or nucl-MGMT also conferred a similar level of resistance to methyl methanesulfonate (MMS) and temozolomide (TMZ) but simultaneous overexpression in both cellular compartments was neither additive nor synergistic. When human CD34(+) cells were infected with oncoretroviral vectors that targeted O(6)-benzylguanine (6BG)-resistant MGMT (MGMT(P140K)) to the nucleus or the mitochondria, committed progenitors derived from infected cells were resistant to 6BG/BCNU or 6BG/TMZ. These studies indicate that mitochondrial or nuclear targeting of MGMT protects hematopoietic cells against cell killing by BCNU, TMZ, and MMS, which is consistent with the possibility that mitochondrial DNA damage and nuclear DNA damage contribute equally to alkylating agent-induced cell killing during chemotherapy.

Method for reactivating solid catalysts used in alkylation reactions

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Ginosar, Daniel M.; Thompson, David N.; Coates, Kyle; Zalewski, David J.; Fox, Robert V.

2003-06-17

A method for reactivating a solid alkylation catalyst is provided which can be performed within a reactor that contains the alkylation catalyst or outside the reactor. Effective catalyst reactivation is achieved whether the catalyst is completely deactivated or partially deactivated. A fluid reactivating agent is employed to dissolve catalyst fouling agents and also to react with such agents and carry away the reaction products. The deactivated catalyst is contacted with the fluid reactivating agent under pressure and temperature conditions such that the fluid reactivating agent is dense enough to effectively dissolve the fouling agents and any reaction products of the fouling agents and the reactivating agent. Useful pressures and temperatures for reactivation include near-critical, critical, and supercritical pressures and temperatures for the reactivating agent. The fluid reactivating agent can include, for example, a branched paraffin containing at least one tertiary carbon atom, or a compound that can be isomerized to a molecule containing at least one tertiary carbon atom.

Cumulative alkylating agent exposure and semen parameters in adult survivors of childhood cancer: a report from the St Jude Lifetime Cohort Study.

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Green, Daniel M; Liu, Wei; Kutteh, William H; Ke, Raymond W; Shelton, Kyla C; Sklar, Charles A; Chemaitilly, Wassim; Pui, Ching-Hon; Klosky, James L; Spunt, Sheri L; Metzger, Monika L; Srivastava, DeoKumar; Ness, Kirsten K; Robison, Leslie L; Hudson, Melissa M

2014-10-01

Few data define the dose-specific relation between alkylating agent exposure and semen variables in adult survivors of childhood cancer. We undertook this study to test the hypothesis that increased exposure to alkylating agents would be associated with decreased sperm concentration in a cohort of adult male survivors of childhood cancer who were not exposed to radiation therapy for their childhood cancer. We did semen analysis on 214 adult male survivors of childhood cancer (median age 7·7 years [range 0·01-20·3] at diagnosis, 29·0 years [18·4-56·1] at assessment, and a median of 21·0 years [10·5-41·6] since diagnosis) who had received alkylating agent chemotherapy but no radiation therapy. Alkylating agent exposure was estimated using the cyclophosphamide equivalent dose (CED). Odds ratios (ORs) and 95% CIs for oligospermia (sperm concentration >0 and <15 million per mL) and azoospermia were calculated with logistic regression modelling. Azoospermia was noted in 53 (25%) of 214 participants, oligospermia in 59 (28%), and normospermia (sperm concentration ≥15 million per mL) in 102 (48%) participants. 31 (89%) of 35 participants who received CED less than 4000 mg/m(2) were normospermic. CED was negatively correlated with sperm concentration (correlation coefficient=-0·37, p<0·0001). Mean CED was 10 830 mg/m(2) (SD 7274) in patients with azoospermia, 8480 mg/m(2) (4264) in patients with oligospermia, and 6626 mg/m(2) (3576) in patients with normospermia. In multivariable analysis, CED was significantly associated with an increased risk per 1000 mg/m(2) CED for azoospermia (OR 1·22, 95% CI 1·11-1·34), and for oligospermia (1·14, 1·04-1·25), but age at diagnosis and age at assessment were not. Impaired spermatogenesis was unlikely when the CED was less than 4000 mg/m(2). Although sperm concentration decreases with increasing CED, there was substantial overlap of CED associated with normospermia, oligospermia, and azoospermia. These data can

HeLa Cells Containing a Truncated Form of DNA Polymerase Beta are More Sensitized to Alkylating Agents than to Agents Inducing Oxidative Stress.

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Khanra, Kalyani; Chakraborty, Anindita; Bhattacharyya, Nandan

2015-01-01

The present study was aimed at determining the effects of alkylating and oxidative stress inducing agents on a newly identified variant of DNA polymerase beta (polβ Δ208-304) specific for ovarian cancer. Pol β Δ208-304 has a deletion of exons 11-13 which lie in the catalytic part of enzyme. We compared the effect of these chemicals on HeLa cells and HeLa cells stably transfected with this variant cloned into in pcDNAI/neo vector by MTT, colony forming and apoptosis assays. Polβ Δ208-304 cells exhibited greater sensitivity to an alkylating agent and less sensitivity towards H2O2 and UV when compared with HeLa cells alone. It has been shown that cell death in Pol β Δ208-304 transfected HeLa cells is mediated by the caspase 9 cascade. Exon 11 has nucleotidyl selection activity, while exons 12 and 13 have dNTP selection activity. Hence deletion of this part may affect polymerizing activity although single strand binding and double strand binding activity may remain same. The lack of this part may adversely affect catalytic activity of DNA polymerase beta so that the variant may act as a dominant negative mutant. This would represent clinical significance if translated into a clinical setting because resistance to radiation or chemotherapy during the relapse of the disease could be potentially overcome by this approach.

Mutational specificity of alkylating agents and the influence of DNA repair

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Horsfall, M.J.; Gordon, A.J.; Burns, P.A.; Zielenska, M.; van der Vliet, G.M.; Glickman, B.W. (York Univ., Toronto, Ontario (Canada))

1990-01-01

Alkylating treatments predominantly induce G:C = greater than A:T transitions, consistent with the predicted significance of the miscoding potential of the O6-alG lesion. However, the frequency and distribution of these events induced by any one compound may be diagnostic. SN1 agents that act via an alkyldiazonium cation, such as the N-nitroso compounds, preferentially generate G:C = greater than A:T transitions at 5'-RG-3' sites, while the more SN2 alkylsulfates and alkylalkane-sulfonates do not. The precise nature of this site bias and the possibility of strand bias are target dependent. The extent of this site bias and the contribution of other base substitutions are substituent size dependent. A similar 5'-RT-3' effect is seen for A:T = greater than G:C transitions, presumably directed by O4-alT lesions. The 5'-RG-3' effect, at least, likely reflects a deposition specificity arising from some aspect of helix geometry, although it may be further exaggerated by alkylation-specific repair. Excision repair appears to preferentially reduce the occurrence of ethylation-induced G:C = greater than A:T and A:T = greater than G:C transitions at sites flanked by A:T base pairs. This may be due to an enhancement of the helical distortion imposed by damage at such positions. A similar effect is not seen for methylation-induced mutations and in the case of propyl adducts, the influence of excision repair on the ultimate distribution of mutation cannot be as easily defined with respect to neighbouring sequence. 199 references.

Ovarian reserve after treatment with alkylating agents during childhood.

Science.gov (United States)

Thomas-Teinturier, Cécile; Allodji, Rodrigue Sétchéou; Svetlova, Ekaterina; Frey, Marie-Alix; Oberlin, Odile; Millischer, Anne-Elodie; Epelboin, Sylvie; Decanter, Christine; Pacquement, Helene; Tabone, Marie-Dominique; Sudour-Bonnange, Helene; Baruchel, André; Lahlou, Najiba; De Vathaire, Florent

2015-06-01

What is the effect of different alkylating agents used without pelvic radiation to treat childhood cancer in girls on the ovarian reserve in survivors? Ovarian reserve seems to be particularly reduced in survivors who received procarbazine (in most cases for Hodgkin lymphoma) or high-dose chemotherapy; procarbazine but not cyclophosphamide dose is associated with diminished ovarian reserve. A few studies have demonstrated diminished ovarian reserve in survivors after various combination therapies, but the individual role of each treatment is difficult to assess. Prospective cross-sectional study, involving 105 survivors and 20 controls. One hundred and five survivors aged 17-40 years and 20 controls investigated on Days 2-5 of a menstrual cycle or Day 7 of an oral contraceptive pill-free interval. ovarian surface area (OS), total number of antral follicles (AFC), serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol and anti-Müllerian hormone (AMH). Survivors had a lower OS than controls: 3.5 versus 4.4 cm(2) per ovary (P = 0.0004), and lower AMH levels: 10.7 versus 22 pmol/l (P = 0.003). Ovarian markers (OS, AMH, AFC) were worse in patients who received high-dose compared with conventional-dose alkylating agents (P = 0.01 for OS, P = 0.002 for AMH, P < 0.0001 for AFC). Hodgkin lymphoma survivors seemed to have a greater reduction in ovarian reserve than survivors of leukaemia (P = 0.04 for AMH, P = 0.01 for AFC), sarcoma (P = 0.04 for AMH, P = 0.04 for AFC) and other lymphomas (P = 0.04 for AFC). A multiple linear regression analysis showed that procarbazine but not cyclophosphamide nor ifosfamide dose was associated with reduced OS (P = 0.0003), AFC (P = 0.0007), AMH (P < 0.0001) and higher FSH levels (P < 0.0001). The small percentage of participating survivors (28%) from the total cohort does not allow conclusion on fertility issues because of possible response bias. The association between procarbazine and HL makes it

An intron splice acceptor polymorphism in hMSH2 and risk of leukemia after treatment with chemotherapeutic alkylating agents.

Science.gov (United States)

Worrillow, Lisa J; Travis, Lois B; Smith, Alexandra G; Rollinson, Sara; Smith, Andrew J; Wild, Christopher P; Holowaty, Eric J; Kohler, Betsy A; Wiklund, Tom; Pukkala, Eero; Roman, Eve; Morgan, Gareth J; Allan, James M

2003-08-01

We sought to determine whether the -6 exon 13 T>C polymorphism in the DNA mismatch repair gene hMSH2 modulates susceptibility to acute myeloid leukemia after therapy and particularly after O(6)-guanine alkylating chemotherapy. We also determined the extent of microsatellite instability (MSI) in therapy-related acute myeloid leukemia (t-AML) as a marker of dysfunctional DNA mismatch repair. Using a novel restriction fragment length polymorphism, verified by direct sequencing, we have genotyped 91 t-AML cases, 420 de novo acute myeloid leukemia cases, and 837 controls for the hMSH2 -6 exon 13 polymorphism. MSI was evaluated in presentation bone marrow from 34 cases using the mononucleotide microsatellite markers BAT16, BAT25, and BAT26. Distribution of the hMSH2 -6 exon 13 polymorphism was not significantly different between de novo acute myeloid leukemia cases and controls, with heterozygotes and homozygotes for the variant (C) allele representing 12.2 and 1.6%, respectively, of the control population. However, the variant (C) hMSH2 allele was significantly overrepresented in t-AML cases that had previously been treated with O(6)-guanine alkylating agents, including cyclophosphamide and procarbazine, compared with controls (odds ratio, 4.02; 95% confidence interval, 1.40-11.37). Thirteen of 34 (38%) t-AML cases were MSI positive, and 2 of these 13 cases were homozygous for the variant (C) allele, a frequency substantially higher than in the control population. Association of the hMSH2 -6 exon 13 variant (C) allele with leukemia after O(6)-guanine alkylating agents implicates this allele in conferring a nondisabling DNA mismatch repair defect with concomitant moderate alkylation tolerance, which predisposes to the development of t-AML via the induction of DNA mismatch repair-disabling mutations and high-grade MSI. Homozygosity for the hMSH2 variant in 2 of 13 MSI-positive t-AML cases provides some support for this model.

Evaluation of fluorine-18-labeled alkylating agents as potential synthons for the labeling of oligonucleotides

Energy Technology Data Exchange (ETDEWEB)

Vries, E.F.J. de E-mail: e.f.j.de.vries@pet.azg.nl; Vroegh, Joke; Elsinga, P.H.; Vaalburg, Willem

2003-04-01

Six fluorine-18-labeled alkylating agents were selected as potentially suitable synthons for the labeling of antisense oligonucleotides. The selected synthons were evaluated in a model reaction with the monomer adenosine 5'-O-thiomonophosphate. Of these synthons, {alpha}-bromo-{alpha}'-[{sup 18}F]fluoro-m-xylene and N-(4-[{sup 18}F]fluorobenzyl)-2-bromoacetamide were found to be the most promising. Labeling with the former synthon was less complicated and time consuming and gave higher uncorrected overall yields. The latter synthon required smaller amounts of the costly precursor to achieve acceptable labeling yields.

Antioxidant and antigenotoxic role of recombinant human erythropoeitin against alkylating agents: cisplatin and mitomycin C in cultured Vero cells.

Science.gov (United States)

Rjiba-Touati, Karima; Ayed-Boussema, Imen; Soualeh, Nidhal; Achour, Abdellatif; Bacha, Hassen; Abid, Salwa

2013-08-01

Cisplatin (CDDP) and mitomycin C (MMC), two alkylating agents used against various solid tumours, are a common source of acute kidney injury. Thus, strategies for minimizing CDDP and MMC toxicity are of a clinical interest. In this study, we aimed to investigate the protective role of recombinant human erythropoietin (rhEPO) against oxidative stress and genotoxicity induced by CDDP and MMC in cultured Vero cells. Three types of treatments were performed: (i) cells were treated with rhEPO 24 h before exposure to CDDP/MMC (pre-treatment), (ii) cells were treated with rhEPO and CDDP/MMC simultaneously (co-treatment), (iii) cells were treated with rhEPO 24 h after exposure to CDDP/MMC (post-treatment). Our results showed that rhEPO decreased the reactive oxygen species levels, the malondialdehyde levels and ameliorated glutathione (reduced and oxidized glutathione) modulation induced by CDDP and MMC in cultured Vero cells. Furthermore, rhEPO administration prevented alkylating agents-induced DNA damage accessed by comet test. Altogether, our results suggested a protective role of rhEPO, against CDDP- and MMC-induced oxidative stress and genotoxicity, especially in pre-treatment condition.

Effects of photochemically activated alkylating agents of the FR900482 family on chromatin.

Science.gov (United States)

Subramanian, Vidya; Ducept, Pascal; Williams, Robert M; Luger, Karolin

2007-05-01

Bioreductive alkylating agents are an important class of clinical antitumor antibiotics that crosslink and monoalkylate DNA. Here, we use a synthetic, photochemically activated derivative of FR400482 to investigate the molecular mechanism of this class of drugs in a biologically relevant context. We find that the organization of DNA into nucleosomes effectively protects it against drug-mediated crosslinking, while permitting monoalkylation. This modification has the potential to lead to the formation of covalent crosslinks between chromatin and nuclear proteins. Using in vitro approaches, we found that interstrand crosslinking of free DNA results in a significant decrease in basal and activated transcription. Finally, crosslinked plasmid DNA is inefficiently assembled into chromatin. Our studies suggest pathways for the clinical effectiveness of this class of reagents.

Functional copolymer/organo-MMT nanoarchitectures. VI. Synthesis and characterization of novel nanocomposites by interlamellar controlled/living radical copolymerization via preintercalated RAFT-agent/organoclay complexes.

Science.gov (United States)

Rzayev, Zakir M O; Söylemez, A Ernur

2011-04-01

We have developed a new approach for the synthesis of polymer nanocomposites using a bifunctional reversible addition-fragmentation chain transfer (RAFT) agent, two types of organo-montmorillonites, such as a non-reactive dimethyldodecyl ammonium (DMDA)-MMT and a reactive octadecylamine (ODA)-MMT organoclays, and a radical initiator. The method includes the following stages: (1) synthesis of RAFT intercalated O-MMTs by a physical or chemical interaction of the RAFT agent having two pendant carboxylic groups [S,S-bis(alpha,alpha'-dimethyl-alpha"-acetic acid)trithiocarbonate] with surface alkyl amines of O-MMT containing tertiary ammonium cation or primary amine groups through strong H-bonding and complexing/amidization reactions, respectively, and (2) utilization of these well-dispersed and intercalated RAFT ... O-MMT complexes and their amide derivatives as new modified RAFT agents in radical-initiated interlamellar controlled/living copolymerization of itaconic acid (IA)-n-butylmethacrylate (BMA) monomer pair. The structure and compositions of the synthesized RAFT ... O-MMT complexes and functional copolymer/O-MMT hybrids were confirmed by FTIR, XRD, thermal (DSC-TGA), SEM and TEM morphology analyses. It was demonstrated that the degree of interaction/exfoliation, morphology and thermal behavior of nanocomposites significantly depended on the type of organoclay and in situ interaction, as well as on the content of flexible butyl-ester linkages as a internal plasticizer. The results of the comparative analysis of the nanocomposites structure-composition-property relations show that the functional copolymer-organoclay hybrids prepared with reactive RAFT ... ODA-MMT complex and containing a combination of partially intercalated and predominantly exfoliated nano-structures exhibit relatively higher thermal stability and fine dispersed morphology. These effects were explained by in situ interfacial chemical reactions through amidization of RAFT with surface alkyl amine

A novel acetylation cycle of transcription co-activator Yes-associated protein that is downstream of Hippo pathway is triggered in response to SN2 alkylating agents.

Science.gov (United States)

Hata, Shoji; Hirayama, Jun; Kajiho, Hiroaki; Nakagawa, Kentaro; Hata, Yutaka; Katada, Toshiaki; Furutani-Seiki, Makoto; Nishina, Hiroshi

2012-06-22

Yes-associated protein (YAP) is a transcriptional co-activator that acts downstream of the Hippo signaling pathway and regulates multiple cellular processes. Although cytoplasmic retention of YAP is known to be mediated by Hippo pathway-dependent phosphorylation, post-translational modifications that regulate YAP in the nucleus remain unclear. Here we report the discovery of a novel cycle of acetylation/deacetylation of nuclear YAP induced in response to S(N)2 alkylating agents. We show that after treatment of cells with the S(N)2 alkylating agent methyl methanesulfonate, YAP phosphorylation mediated by the Hippo pathway is markedly reduced, leading to nuclear translocation of YAP and its acetylation. This YAP acetylation occurs on specific and highly conserved C-terminal lysine residues and is mediated by the nuclear acetyltransferases CBP (CREB binding protein) and p300. Conversely, the nuclear deacetylase SIRT1 is responsible for YAP deacetylation. Intriguingly, we found that YAP acetylation is induced specifically by S(N)2 alkylating agents and not by other DNA-damaging stimuli. These results identify a novel YAP acetylation cycle that occurs in the nucleus downstream of the Hippo pathway. Intriguingly, our findings also indicate that YAP acetylation is involved in responses to a specific type of DNA damage.

A Novel Acetylation Cycle of Transcription Co-activator Yes-associated Protein That Is Downstream of Hippo Pathway Is Triggered in Response to SN2 Alkylating Agents*

Science.gov (United States)

Hata, Shoji; Hirayama, Jun; Kajiho, Hiroaki; Nakagawa, Kentaro; Hata, Yutaka; Katada, Toshiaki; Furutani-Seiki, Makoto; Nishina, Hiroshi

2012-01-01

Yes-associated protein (YAP) is a transcriptional co-activator that acts downstream of the Hippo signaling pathway and regulates multiple cellular processes. Although cytoplasmic retention of YAP is known to be mediated by Hippo pathway-dependent phosphorylation, post-translational modifications that regulate YAP in the nucleus remain unclear. Here we report the discovery of a novel cycle of acetylation/deacetylation of nuclear YAP induced in response to SN2 alkylating agents. We show that after treatment of cells with the SN2 alkylating agent methyl methanesulfonate, YAP phosphorylation mediated by the Hippo pathway is markedly reduced, leading to nuclear translocation of YAP and its acetylation. This YAP acetylation occurs on specific and highly conserved C-terminal lysine residues and is mediated by the nuclear acetyltransferases CBP (CREB binding protein) and p300. Conversely, the nuclear deacetylase SIRT1 is responsible for YAP deacetylation. Intriguingly, we found that YAP acetylation is induced specifically by SN2 alkylating agents and not by other DNA-damaging stimuli. These results identify a novel YAP acetylation cycle that occurs in the nucleus downstream of the Hippo pathway. Intriguingly, our findings also indicate that YAP acetylation is involved in responses to a specific type of DNA damage. PMID:22544757

Suppression of alkylating agent induced cell transformation and gastric ulceration by low-dose alkylating agent pretreatment

International Nuclear Information System (INIS)

Onodera, Akira; Kawai, Yuichi; Kashimura, Asako; Ogita, Fumiya; Tsutsumi, Yasuo; Itoh, Norio

2013-01-01

Highlights: •Low-dose MNNG pretreatment suppresses high-dose MNNG induced in vitro transformation. •Gastric ulcers induced by high-dose MNNG decreased after low-dose MNNG pretreatment. •Efficacy of low-dose MNNG related to resistance of mutation and oxidative stress. -- Abstract: Exposure to mild stress by chemicals and radiation causes DNA damage and leads to acquired stress resistance. Although the linear no-threshold (LNT) model of safety assessment assumes risk from any dose, evidence from radiological research demonstrates a conflicting hormetic phenomenon known as the hormesis effect. However, the mechanisms underlying radiation hormesis have not yet been clarified, and little is known about the effects of low doses of chemical carcinogens. We analyzed the efficacy of pretreatment with low doses of the alkylating agent N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) on the subsequent induction of cell transformation and gastric ulceration by high-dose MNNG. We used an in vitro Balb/3T3 A31-1-1 cell transformation test and monitored the formation of gastric ulcers in 5-week-old male ICR mice that were administered MNNG in drinking water. The treatment concentrations of MNNG were determined by the cell survival rate and past reports. For low-dose in vitro and in vivo experiments, MNNG was used at 0.028 μM, and 2.8 μg/mL, respectively. The frequency of cell transformation induced by 10 μm MNNG was decreased by low-dose MNNG pretreatment to levels similar to that of spontaneous transformation. In addition, reactive oxygen species (ROS) and mutation frequencies induced by 10 μm MNNG were decreased by low-dose MNNG pretreatment. Importantly, low-dose MNNG pretreatment had no effect on cell proliferation. In vivo studies showed that the number of gastric ulcers induced by 1 mg/mL MNNG decreased after low-dose MNNG pretreatment. These data indicate that low-dose pretreatment with carcinogens may play a beneficial role in the prevention of chemical toxicity

Suppression of alkylating agent induced cell transformation and gastric ulceration by low-dose alkylating agent pretreatment

Energy Technology Data Exchange (ETDEWEB)

Onodera, Akira, E-mail: onodera@pharm.kobegakuin.ac.jp [Department of Toxicology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Department of Pharmaceutical Sciences, Kobegakuin University, 1-1-3 Minatojima, Chuo-ku, Kobe 650-8586 (Japan); Kawai, Yuichi [Department of Pharmaceutical Sciences, Kobegakuin University, 1-1-3 Minatojima, Chuo-ku, Kobe 650-8586 (Japan); Kashimura, Asako; Ogita, Fumiya; Tsutsumi, Yasuo; Itoh, Norio [Department of Toxicology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871 (Japan)

2013-06-14

Highlights: •Low-dose MNNG pretreatment suppresses high-dose MNNG induced in vitro transformation. •Gastric ulcers induced by high-dose MNNG decreased after low-dose MNNG pretreatment. •Efficacy of low-dose MNNG related to resistance of mutation and oxidative stress. -- Abstract: Exposure to mild stress by chemicals and radiation causes DNA damage and leads to acquired stress resistance. Although the linear no-threshold (LNT) model of safety assessment assumes risk from any dose, evidence from radiological research demonstrates a conflicting hormetic phenomenon known as the hormesis effect. However, the mechanisms underlying radiation hormesis have not yet been clarified, and little is known about the effects of low doses of chemical carcinogens. We analyzed the efficacy of pretreatment with low doses of the alkylating agent N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) on the subsequent induction of cell transformation and gastric ulceration by high-dose MNNG. We used an in vitro Balb/3T3 A31-1-1 cell transformation test and monitored the formation of gastric ulcers in 5-week-old male ICR mice that were administered MNNG in drinking water. The treatment concentrations of MNNG were determined by the cell survival rate and past reports. For low-dose in vitro and in vivo experiments, MNNG was used at 0.028 μM, and 2.8 μg/mL, respectively. The frequency of cell transformation induced by 10 μm MNNG was decreased by low-dose MNNG pretreatment to levels similar to that of spontaneous transformation. In addition, reactive oxygen species (ROS) and mutation frequencies induced by 10 μm MNNG were decreased by low-dose MNNG pretreatment. Importantly, low-dose MNNG pretreatment had no effect on cell proliferation. In vivo studies showed that the number of gastric ulcers induced by 1 mg/mL MNNG decreased after low-dose MNNG pretreatment. These data indicate that low-dose pretreatment with carcinogens may play a beneficial role in the prevention of chemical toxicity

Modulation of the toxicity and antitumour activity of alkylating drugs by steroids.

OpenAIRE

Shepherd, R.; Harrap, K. R.

1982-01-01

The steroids prednisolone and progesterone significantly altered the therapeutic indices of the alkylating agents, nitrogen mustard, melphalan, cyclophosphamide, phenyl acetic mustard and chlorambucil. For nitrogen mustard, chlorambucil and phenyl acetic mustard, prednisolone reduced host toxicity in the rat and enhanced the antitumour effectiveness against alkylating-agent-resistant strains of the Yoshida sarcoma and Walker carcinosarcoma. Progesterone also increased the therapeutic index of...

The effect of various S-alkylating agents on the chromatographic behavior of cysteine-containing peptides in reversed-phase chromatography.

Science.gov (United States)

Jiang, Xuehui; Shamshurin, Dmitry; Spicer, Vic; Krokhin, Oleg V

2013-02-01

We investigate the influence of various alkylation chemistries on the reversed phase (RP) HPLC behavior of Cys-containing peptides under the most popular RP-HPLC conditions used in proteomics: C18 phases with trifluoroacetic acid (TFA) or formic acid (FA) as the ion pairing modifiers, and separation at pH 10. Akylating agents studied are iodoacetamide (IAM), iodoacetic acid (IAA), 4-vinylpyridine (4-VP), acrylamide (AA) and methyl methanethiosulfonate (MMTS). These were compared against the retention of identical peptides without alkylation, i.e. free cysteines. The intrinsic hydrophobicity values of the Cys residue under formic acid conditions for these modifications were found to increase in the following order: 4-VPalkylated Cys using TFA eluent. Switching to a basic condition dramatically decreases the retention of free cysteine and IAA-alkylated analytes due to the ionization of side-chains. The opposite effect is observed for 4-VP, which become neutral at basic pHs. The careful measurement of the hydrophobic contributions for these residues is vital to the development of accurate peptide retention prediction models; the incorporation of these modifications into our Sequence Specific Retention Calculator model is presented. Copyright © 2013. Published by Elsevier B.V.

Identifying and annotating human bifunctional RNAs reveals their versatile functions.

Science.gov (United States)

Chen, Geng; Yang, Juan; Chen, Jiwei; Song, Yunjie; Cao, Ruifang; Shi, Tieliu; Shi, Leming

2016-10-01

Bifunctional RNAs that possess both protein-coding and noncoding functional properties were less explored and poorly understood. Here we systematically explored the characteristics and functions of such human bifunctional RNAs by integrating tandem mass spectrometry and RNA-seq data. We first constructed a pipeline to identify and annotate bifunctional RNAs, leading to the characterization of 132 high-confidence bifunctional RNAs. Our analyses indicate that bifunctional RNAs may be involved in human embryonic development and can be functional in diverse tissues. Moreover, bifunctional RNAs could interact with multiple miRNAs and RNA-binding proteins to exert their corresponding roles. Bifunctional RNAs may also function as competing endogenous RNAs to regulate the expression of many genes by competing for common targeting miRNAs. Finally, somatic mutations of diverse carcinomas may generate harmful effect on corresponding bifunctional RNAs. Collectively, our study not only provides the pipeline for identifying and annotating bifunctional RNAs but also reveals their important gene-regulatory functions.

The light activated alkylation of glycine

International Nuclear Information System (INIS)

Knowles, H.S.

2001-04-01

The work contained in this thesis focuses on the light-initiated alkylation of the α-centre of glycine compounds. The elaboration of the glycines in this manner represents a versatile, clean and cost effective alternative to ionic routes to higher α-amino acids. Preliminary investigations demonstrated that a range of nitrogen protecting groups were compatible with the radical alkylation. A variety of solvents could also be used although solvents with easily removable hydrogen atoms were found to interfere with the alkylation. Furthermore, a number of photo-initiators were investigated and the use of di-tert-butyl peroxide was found to afford the desired phenylalanine products in up to 27% yield (54% based on recovered starting material) when toluene was used as the alkylating agent. A range of different precursor concentrations was investigated and it was found that the optimum concentration of the glycine precursor was 0.13 mol dm -3 ; the phenylalanine yields were reduced when the concentration was less than this value. Owing to the poor UV absorption by di-tert-butyl peroxide, benzophenone (an effective photosensitiser) was added to the reaction mixture and this was shown to increase the alkylation yields. The ratio of reagents which produced the highest yield of phenylalanine products was found to be 1 : 5 : 5 : 10 for glycine : di-tert-butyl peroxide : benzophenone : toluene. This produced the phenylalanine product in up to 37% yield (57% based on recovered starting material). A number of substituents. (e.g. F, Cl etc.) could be attached to the aromatic ring of the toluene alkylating agent, affording substituted phenylalanines in 5 - 36% under these conditions. The formation of chiral phenylalanine products was probed by reacting glycine precursors bearing chiral auxiliaries. However, low diastereoselectivities were observed; the d.r. ranged from 1 : 1.1 to 1 : 1.5 only when chiral ester and amide protecting groups were used. In the final chapter, the α-alkylation

Molecular mechanisms of adaptive response to alkylating agents in Escherichia coli and some remarks on O(6)-methylguanine DNA-methyltransferase in other organisms.

Science.gov (United States)

Kleibl, Karol

2002-09-01

Alkylating agents are environmental genotoxic agents with mutagenic and carcinogenic potential, however, their properties are also exploited in the treatment of malignant diseases. O(6)-Methylguanine is an important adduct formed by methylating agents that, if not repaired, can lead to mutations and death. Its repair is carried out by O(6)-methylguanine DNA-methyltransferase (MTase) in an unique reaction in which methyl groups are transferred to the cysteine acceptor site of the protein itself. Exposure of Escherichia coli cells to sublethal concentrations of methylating agents triggers the expression of a set of genes, which allows the cells to tolerate DNA lesions, and this kind of inducible repair is called the adaptive response. The MTase of E. coli, encoded by the ada gene was the first MTase to be discovered and one of best characterised. Its repair and regulatory mechanisms are understood in considerable detail and this bacterial protein played a key role in identification of its counterparts in other living organisms. This review summarises the nature of alkylation damage in DNA and our current knowledge about the adaptive response in E. coli. I also include a brief mention of MTases from other organisms with the emphasis on the human MTase, which could play a crucial role in both cancer prevention and cancer treatment.

Abnormal sensitivity of skin fibroblasts from familial polyposis patients to DNA alkylating agents

International Nuclear Information System (INIS)

Barfknecht, T.R.; Little, J.B.

1982-01-01

Fibroblast cell strains derived from different patients all afflicted with genetic predisposing to the development of intestinal polyposis and cancer were tested for their sensitivity to the lethal effects of the DNA alkylating agents methylmethanesulfonate (MMS), ethyl methanesulfonate, N-methyl-N'-nitro-N-nitrosoguanidine, and 4-nitroquinoline 1-oxide. The genetic syndromes studied were: (a) adenomatosis of the colon and rectum only, an autosomal dominant trait; (b) Turcot's syndrome, a rare autosomal recessive polyposis syndrome also characterized by central nervous system tumors; and (c) Gardner's syndrome, an autosomal dominant syndrome which, in addition to intestinal polyposis, is also clinically characterized by osteomas and soft tissue tumors. Fibroblasts from a patient with Turcot's syndrome were hypersensitive to MMS, having a D0 value of 0.24 mM (p less than 0.01) versus the normal average D0 of 0.36 mM and a D10 value of 0.95 mM (p less than 0.01) compared with the normal average value of 1.3 mM. Fibroblasts from the Gardner's syndrome proband were moderately sensitive to MMS, ethyl methanesulfonate, and N-methyl-N'-nitro-N-nitrosoguanidine due to significant differences of D10 values of 0.60 mM (p less than 0.01), 15 mM (p less than 0.01), and 4.8 microM (p less than 0.025), respectively, versus the normal average values of 1.3 mM, 28 mM, and 9.4 microM. Fibroblasts from the clinically affected Gardner's syndrome daughter of the proband were significantly more sensitive to MMS treatment, D0 of 0.22 mM (p less than 0.01) versus the normal average D0 of 0.36 mM and a D10 of 0.97 mM (p less than 0.01) versus the normal average. This differential sensitivity to the several DNA alkylating agents suggests that different mechanisms of hypersensitivity to these chemicals may be associated with fibroblasts from the various forms of familial polyposis

Biomolecule conjugation strategy using novel water-soluble phosphine-based chelating agents

Science.gov (United States)

Katti, Kattesh V.; Gali, Hariprasad; Volkert, Wynn A.

2004-08-24

This invention describes a novel strategy to produce phosphine-functionalized biomolecules (e.g. peptides or proteins) for potential use in the design and development of site-specific radiopharmaceuticals for diagnosis or therapy of specific cancers. Hydrophilic alkyl phosphines, in general, tend to be oxidatively unstable. Therefore, incorporation of such phosphine functionalities on peptide (and other biomolecule) backbones, without oxidizing the P.sup.III centers, is difficult. In this context this discovery reports on a new technology by which phosphines, in the form of bifunctional chelating agents, can be directly incorporated on biomolecular backbones using manual synthetic or solid phase peptide synthesis methodologies. The superior ligating abilities of phosphine ligands, with various diagnostically (e.g. TC-99m) or therapeutically (e.g. Re186/188, Rh-105, Au-199) useful radiometals, coupled with the findings that the resulting complexes demonstrate high in vivo stability makes this approach useful in the development of radiolabeled biomolecules for applications in the design of tumor-specific radiopharmaceuticals.

Dose-Effect Relationship of Alkylating Agents on Testicular Function in Male Survivors of Childhood Lymphoma.

Science.gov (United States)

Servitzoglou, Marina; De Vathaire, Florent; Oberlin, Odile; Patte, Catherine; Thomas-Teinturier, Cécile

2015-01-01

The purpose of our study was to assess the gonadal function in male survivors of childhood lymphoma. We studied 171 male survivors of childhood lymphoma (83 with B-cell non-Hodgkin lymphoma [B-NHL], 32 with T-cell non-Hodgkin lymphoma [T-NHL], 50 with Hodgkin lymphoma [HL], and 6 with anaplastic large-cell lymphoma [ALCL]), measuring follicle-stimulating hormone [FSH] and luteinizing hormone [LH] levels at a median age of 21.1 (17-30.4) years after a median delay of 9.3 (2-22.4) years from treatment. FSH levels were above normal range (≥10 IU/L) in 42.1% and LH levels ≥8 IU/L in only 8.9% of survivors. In multivariate analysis, only the following chemotherapeutic agents were associated with higher FSH or LH levels: cyclophosphamide (P alkylating agents on childhood lymphoma survivors is dose dependent and not correlated to diagnosis, age, or pubertal status at diagnosis.

Boron-Catalyzed N-Alkylation of Amines using Carboxylic Acids.

Science.gov (United States)

Fu, Ming-Chen; Shang, Rui; Cheng, Wan-Min; Fu, Yao

2015-07-27

A boron-based catalyst was found to catalyze the straightforward alkylation of amines with readily available carboxylic acids in the presence of silane as the reducing agent. Various types of primary and secondary amines can be smoothly alkylated with good selectivity and good functional-group compatibility. This metal-free amine alkylation was successfully applied to the synthesis of three commercial medicinal compounds, Butenafine, Cinacalcet. and Piribedil, in a one-pot manner without using any metal catalysts. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Short Review on the Synthetic Strategies of Duocarmycin Analogs that are Powerful DNA Alkylating Agents.

Science.gov (United States)

Patil, Pravin C; Satam, Vijay; Lee, Moses

2015-01-01

The duocarmycins and CC-1065 are members of a class of DNA minor groove, AT-sequence selective, and adenine-N3 alkylating agents, isolated from Streptomyces sp. that exhibit extremely potent cytotoxicity against the growth of cancer cells grown in culture. Initial synthesis and structural modification of the cyclopropa[c] pyrrolo[3,2-e]indole (CPI) DNA-alkylating motif as well as the indole non-covalent binding region in the 1980s have led to several compounds that entered clinical trials as potential anticancer drugs. However, due to significant systemic toxicity none of the analogs have passed clinical evaluation. As a result, the intensity in the design, synthesis, and development of novel analogs of the duocarmycins has continued. Accordingly, in this review, which covers a period from the 1990s through the present time, the design and synthesis of duocarmycin SA are described along with the synthesis of novel and highly cytotoxic analogs that lack the chiral center. Examples of achiral analogs of duocarmycin SA described in this review include seco-DUMSA (39 and 40), seco-amino-CBI-TMI (13, Centanamycin), and seco-hydroxy-CBI-TMI (14). In addition, another novel class of biologically active duocarmycin SA analogs that contained the seco-iso-cyclopropylfurano[2,3-e]indoline (seco-iso-CFI) and seco-cyclopropyltetrahydrofurano[2,3-f]quinoline (seco-CFQ) DNA alkylating submit was also designed and synthesized. The synthesis of seco-iso-CFI-TMI (10, Tafuramycin A) and seco-CFQ-TMI (11, Tafuramycin B) is included in this review.

Sensitization of melanoma cells to alkylating agent-induced DNA damage and cell death via orchestrating oxidative stress and IKK? inhibition

OpenAIRE

Tse, Anfernee Kai-Wing; Chen, Ying-Jie; Fu, Xiu-Qiong; Su, Tao; Li, Ting; Guo, Hui; Zhu, Pei-Li; Kwan, Hiu-Yee; Cheng, Brian Chi-Yan; Cao, Hui-Hui; Lee, Sally Kin-Wah; Fong, Wang-Fun; Yu, Zhi-Ling

2017-01-01

Nitrosourea represents one of the most active classes of chemotherapeutic alkylating agents for metastatic melanoma. Treatment with nitrosoureas caused severe systemic side effects which hamper its clinical use. Here, we provide pharmacological evidence that reactive oxygen species (ROS) induction and IKKβ inhibition cooperatively enhance nitrosourea-induced cytotoxicity in melanoma cells. We identified SC-514 as a ROS-inducing IKKβ inhibitor which enhanced the function of nitrosoureas. Eleva...

Identification in the mu-opioid receptor of cysteine residues responsible for inactivation of ligand binding by thiol alkylating and reducing agents.

Science.gov (United States)

Gaibelet, G; Capeyrou, R; Dietrich, G; Emorine, L J

1997-05-19

Inactivation by thiol reducing and alkylating agents of ligand binding to the human mu-opioid receptor was examined. Dithiothreitol reduced the number of [3H]diprenorphine binding sites. Replacement by seryl residues of either C142 or C219 in extracellular loops 1 and 2 of the mu receptor resulted in a complete loss of opioid binding. A disulfide bound linking C142 to C219 may thus be essential to maintain a functional conformation of the receptor. We also demonstrated that inactivation of ligand binding upon alkylation by N-ethylmaleimide occurred at two sites. Alteration of the more sensitive (IC50 = 20 microM) did not modify antagonists binding but decreased agonist affinity almost 10-fold. Modification of the less reactive site (IC50 = 2 mM) decreased the number of both agonist and antagonist binding sites. The alkylation site of higher sensitivity to N-ethylmaleimide was shown by mutagenesis experiments to be constituted of both C81 and C332 in transmembrane domains 1 and 7 of the mu-opioid receptor.

Synthesis of 4-([{sup 18}F]fluoromethyl)-2-chlorophenylisothiocyanate: a novel bifunctional {sup 18}F-labelling agent

Energy Technology Data Exchange (ETDEWEB)

Wuest, F.; Mueller, M.; Bergmann, R. [Inst. fuer Bioanorganische und Radiopharmazeutische Chemie, FZ-Rossendorf e.V., Dresden (Germany)

2004-07-01

The one-step radiosynthesis of 4-([{sup 18}F]fluoromethyl)-2-chlorophenylisothiocyanate {sup 18}F-7 as a novel bifunctional {sup 18}F-labelling agent is described. Optimised reaction conditions in a remotely controlled synthesis module gave isothiocyanate {sup 18}F-7 in radiochemical yields of 45% (decay-corrected) within 40 min and high radiochemical purity of > 95% after solid-phase-extraction. Coupling of compound {sup 18}F-7 with the primary amine benzylamine as a model reaction afforded the corresponding ((4-[{sup 18}F]fluoromethyl)-2-chloro-phenyl)-benzyl thiourea {sup 18}F-8 in a high radiochemical yield of > 90%. Stability studies of thiourea {sup 18}F-8 in terms of radiodefluorination showed appreciable buffer stability at pH 7.4, whereas significant radiodefluorination was observed when {sup 18}F-8 was incubated in buffers at pH 3.6 and pH 9.4. Preliminary dynamic PET studies with thiourea {sup 18}F-8 in male Wistar rats showed high bone accumulation, indicative of high in vivo radiodefluorination. (orig.)

The antitumour activity of alkylating agents is not correlated with the levels of glutathione, glutathione transferase and O6-alkylguanine-DNA-alkyltransferase of human tumour xenografts. EORTC SPG and PAMM Groups.

Science.gov (United States)

D'Incalci, M; Bonfanti, M; Pifferi, A; Mascellani, E; Tagliabue, G; Berger, D; Fiebig, H H

1998-10-01

Twenty-three human xenografts, including five colon, five gastric, nine lung (three small cell lung cancer) and four breast carcinomas, were investigated for their sensitivity to nitrosoureas, dacarbazine (DTIC), cyclophosphamide (CTX) and cisplatin (DDP). In 12 cases, at least one of the drugs produced complete or partial remission, in 2, a minor regression was observed and in the other 9, treatment was ineffective. The level of sensitivity to each drug, using a score from 1 to 5, was correlated to three biochemical parameters reported to be involved in resistance to alkylating agents: glutathione (GSH), glutathione transferase (GST) and O6-alkylguanine-DNA-alkyltransferase (AGT). A wide variability was found in these parameters in the xenografts investigated. No correlation was found between any of the three parameters and sensitivity to the drugs used or between sensitivity to one drug and to any of the other drugs tested. These results illustrate the complexity of the question of resistance to alkylating agents and indicate that, at least in xenografts, the biochemical parameters examined are not predictive of response to alkylating agents.

Targeting neddylation induces DNA damage and checkpoint activation and sensitizes chronic lymphocytic leukemia B cells to alkylating agents.

Science.gov (United States)

Paiva, C; Godbersen, J C; Berger, A; Brown, J R; Danilov, A V

2015-07-09

Microenvironment-mediated upregulation of the B-cell receptor (BCR) and nuclear factor-κB (NF-κB) signaling in CLL cells resident in the lymph node and bone marrow promotes apoptosis evasion and clonal expansion. We recently reported that MLN4924 (pevonedistat), an investigational agent that inhibits the NEDD8-activating enzyme (NAE), abrogates stromal-mediated NF-κB pathway activity and CLL cell survival. However, the NAE pathway also assists degradation of multiple other substrates. MLN4924 has been shown to induce DNA damage and cell cycle arrest, but the importance of this mechanism in primary neoplastic B cells has not been studied. Here we mimicked the lymph node microenvironment using CD40 ligand (CD40L)-expressing stroma and interleukin-21 (IL-21) to find that inducing proliferation of the primary CLL cells conferred enhanced sensitivity to NAE inhibition. Treatment of the CD40-stimulated CLL cells with MLN4924 resulted in deregulation of Cdt1, a DNA replication licensing factor, and cell cycle inhibitors p21 and p27. This led to DNA damage, checkpoint activation and G2 arrest. Alkylating agents bendamustine and chlorambucil enhanced MLN4924-mediated DNA damage and apoptosis. These events were more prominent in cells stimulated with IL-21 compared with CD40L alone, indicating that, following NAE inhibition, the culture conditions were able to direct CLL cell fate from an NF-κB inhibition to a Cdt1 induction program. Our data provide insight into the biological consequences of targeting NAE in CLL and serves as further rationale for studying the clinical activity of MLN4924 in CLL, particularly in combination with alkylating agents.

Bifunctional bridging linker-assisted synthesis and characterization of TiO{sub 2}/Au nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Žunič, Vojka, E-mail: vojka.zunic@ijs.si, E-mail: vojka13@gmail.com; Kurtjak, Mario; Suvorov, Danilo [Jožef Stefan Institute, Advanced Materials Department (Slovenia)

2016-11-15

Using a simple organic bifunctional bridging linker, titanium dioxide (TiO{sub 2}) nanoparticles were coupled with the Au nanoparticles to form TiO{sub 2}/Au nanocomposites with a variety of Au loadings. This organic bifunctional linker, meso-2,3-dimercaptosuccinic acid, contains two types of functional groups: (i) the carboxyl group, which enables binding to the TiO{sub 2}, and (ii) the thiol group, which enables binding to the Au. In addition, the organic bifunctional linker acts as a stabilizing agent to prevent the agglomeration and growth of the Au particles, resulting in the formation of highly dispersed Au nanoparticles. To form the TiO{sub 2}/Au nanocomposites in a simple way, we deliberately applied a synthetic method that simultaneously ensures: (i) the capping of the Au nanoparticles and (ii) the binding of different amounts of Au to the TiO{sub 2}. The TiO{sub 2}/Au nanocomposites formed with this method show enhanced UV and Vis photocatalytic activities when compared to the pure TiO{sub 2} nanopowders.Graphical Abstract.

Influence of some DNA-alkylating drugs on thermal stability, acid and osmotic resistance of the membrane of whole human erythrocytes and their ghosts.

Science.gov (United States)

Ivanov, I T; Gadjeva, V

2000-09-01

Human erythrocytes and their resealed ghosts were alkylated under identical conditions using three groups of alkylating antitumor agents: mustards, triazenes and chloroethyl nitrosoureas. Osmotic fragility, acid resistance and thermal stability of membranes were changed only in alkylated ghosts in proportion to the concentration of the alkylating agent. All the alkylating agents decreased acid resistance in ghosts. The clinically used drugs sarcolysine, dacarbazine and lomustine all decreased osmotic fragility and thermal stability of ghost membranes depending on their lipophilicity. DM-COOH did not decrease osmotic fragility and thermal stability of ghost membranes, while NEM increased thermal stability of membranes. The preliminary but not subsequent treatment of ghosts with DM-COOH fully abolished the alkylation-induced thermal labilization of ghost membrane proteins while NEM had a partial effect only. The present study gives direct evidence that alkylating agents, having a high therapeutic activity against malignant growth, bind covalently to proteins of cellular membranes.

Evaluation of the persistence in the induction of Sister Chromatid Exchanges (SCE) by alkylating agents; Evaluacion de la persistencia en la induccion de Intercambio en las Cromatidas Hermanas (ICH) por agentes alquilantes

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Rodriguez R, R.; Huerta V, C.; MOrales R, P.R. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

2006-07-01

The persistence in the induction of sister chromatid exchanges (SCE) by the alkylating agents methyl and ethyl-methanesulfonates (MMS and EMS) was evaluated. For it, to groups of mice its were administered a dose of these agents and later its were analyzed the induced SCE's in two periods: early and late. Both agents caused high increments of SCE in the early period and small in the late one; however, the caused lately by EMS was significantly bigger. This late induction of SCE by EMS possibly is associated with an epigenetic change or with the presence of etiladucts in the phosphodiester bonds of the DNA. (Author)

Evaluation of the persistence in the induction of Sister Chromatid Exchanges (SCE) by alkylating agents; Evaluacion de la persistencia en la induccion de Intercambio en las Cromatidas Hermanas (ICH) por agentes alquilantes

Energy Technology Data Exchange (ETDEWEB)

Rodriguez R, R; Huerta V, C; MOrales R, P R [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

2006-07-01

The persistence in the induction of sister chromatid exchanges (SCE) by the alkylating agents methyl and ethyl-methanesulfonates (MMS and EMS) was evaluated. For it, to groups of mice its were administered a dose of these agents and later its were analyzed the induced SCE's in two periods: early and late. Both agents caused high increments of SCE in the early period and small in the late one; however, the caused lately by EMS was significantly bigger. This late induction of SCE by EMS possibly is associated with an epigenetic change or with the presence of etiladucts in the phosphodiester bonds of the DNA. (Author)

Effect of the radioprotector WR 2721 on the response of metastatic Lewis lung carcinoma colonies to alkylating agents

International Nuclear Information System (INIS)

Wist, E.A.

1985-01-01

WR 2721 protected ''artificial'' lung metastases of Lewis lung carcinoma against the cytotoxic effects of cyclophosphamide and melphalan. When mice were pretreated with WR 2721 30 min before exposure to the alkylating agents a significant increase in the number of lung metastases could be observed. This protection of micrometastases had a significant impact on survival in the case of cyclophosphamide treatment, but not in the case of melphalan treatment. The degree of protection at a standard dose of WR 2721 was dose dependent. (orig.)

DNA alkylating agents alleviate silencing of class II transactivator gene expression in L1210 lymphoma cells.

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Murphy, Shawn P; Holtz, Renae; Lewandowski, Nicole; Tomasi, Thomas B; Fuji, Hiroshi

2002-09-15

MHC class II (Ia) Ag expression is inversely correlated with tumorigenicity and directly correlated with immunogenicity in clones of the mouse L1210 lymphoma (1 ). Understanding the mechanisms by which class II Ag expression is regulated in L1210 lymphoma may facilitate the development of immunotherapeutic approaches for the treatment of some types of lymphoma and leukemia. This study demonstrates that the variation in MHC class II Ag expression among clones of L1210 lymphoma is due to differences in the expression of the class II transactivator (CIITA). Analysis of stable hybrids suggests that CIITA expression is repressed by a dominant mechanism in class II-negative L1210 clones. DNA-alkylating agents such as ethyl methanesulfonate and the chemotherapeutic drug melphalan activate CIITA and class II expression in class II negative L1210 cells, and this effect appears to be restricted to transformed cell lines derived from the early stages of B cell ontogeny. Transient transfection assays demonstrated that the CIITA type III promoter is active in class II(-) L1210 cells, despite the fact that the endogenous gene is not expressed, which suggests that these cells have all of the transacting factors necessary for CIITA transcription. An inverse correlation between methylation of the CIITA transcriptional regulatory region and CIITA expression was observed among L1210 clones. Furthermore, 5-azacytidine treatment activated CIITA expression in class II-negative L1210 cells. Collectively, our results suggest that 1) CIITA gene expression is repressed in class II(-) L1210 cells by methylation of the CIITA upstream regulatory region, and 2) treatment with DNA-alkylating agents overcomes methylation-based silencing of the CIITA gene in L1210 cells.

Protection by thiols against poisoning by radiomimetic agents. Chapter 8

International Nuclear Information System (INIS)

Bacq, Z.M.

1975-01-01

A review is presented of reports of studies aimed at detecting a protective effect of thiols against radiomimetic alkylating agents such as those used in cancer therapy (nitrogen mustards (HN2), sarcolysine, busulfan, etc.). Protection by thiols against alkylating agents has been observed in mammals, plant cells, bacteria, isolated mammalian cells and in model systems. The lack of correlation between the protective power of various thiols against radiomimetic agents and ionizing radiations indicates that different mechanisms are involved. Studies have been made of the toxicity of the protector and the competition factor, increased excretion of detoxication products of alkylating agents, decreased alkylation of DNA and RNA both in vivo and in vitro, the protection of hematopoietic tissues, tumours and the adrenal cortex, and the modification of the effects of nitrosoalkylamines, carbon tetrachloride and fungistatics by thiols. The restriction of DNA alkylation by the competitive removal of radiomimetic agents is thought to account for the protective effect of thiols against radiomimetic agents. (U.K.)

Digital PCR quantification of MGMT methylation refines prediction of clinical benefit from alkylating agents in glioblastoma and metastatic colorectal cancer.

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Barault, L; Amatu, A; Bleeker, F E; Moutinho, C; Falcomatà, C; Fiano, V; Cassingena, A; Siravegna, G; Milione, M; Cassoni, P; De Braud, F; Rudà, R; Soffietti, R; Venesio, T; Bardelli, A; Wesseling, P; de Witt Hamer, P; Pietrantonio, F; Siena, S; Esteller, M; Sartore-Bianchi, A; Di Nicolantonio, F

2015-09-01

O(6)-methyl-guanine-methyl-transferase (MGMT) silencing by promoter methylation may identify cancer patients responding to the alkylating agents dacarbazine or temozolomide. We evaluated the prognostic and predictive value of MGMT methylation testing both in tumor and cell-free circulating DNA (cfDNA) from plasma samples using an ultra-sensitive two-step digital PCR technique (methyl-BEAMing). Results were compared with two established techniques, methylation-specific PCR (MSP) and Bs-pyrosequencing. Thresholds for MGMT methylated status for each technique were established in a training set of 98 glioblastoma (GBM) patients. The prognostic and the predictive value of MGMT methylated status was validated in a second cohort of 66 GBM patients treated with temozolomide in which methyl-BEAMing displayed a better specificity than the other techniques. Cutoff values of MGMT methylation specific for metastatic colorectal cancer (mCRC) tissue samples were established in a cohort of 60 patients treated with dacarbazine. In mCRC, both quantitative assays methyl-BEAMing and Bs-pyrosequencing outperformed MSP, providing better prediction of treatment response and improvement in progression-free survival (PFS) (P alkylating agents. © The Author 2015. Published by Oxford University Press on behalf of the European Society for Medical Oncology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Quantum molecular modeling of the interaction between guanine and alkylating agents--2--nitrogen mustard.

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Hamza, A; Broch, H; Vasilescu, D

1996-06-01

The alkylation mechanism of guanine by nitrogen mustard (HN2) was studied by using a supermolecular modeling at the ab initio 6-31G level. Our computations show that interaction of guanine with the aziridinium form of HN2 necessitates a transition state for the N7 alkylation route. The pathway of N7-guanine alkylation by nitrogen and sulfur mustards is discussed on the basis of the Molecular Electrostatic Potential and HOMO-LUMO properties of these molecules.

Gold-catalyzed alkylation of silyl enol ethers with ortho-alkynylbenzoic acid esters

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Yoshinori Yamamoto

2011-05-01

Full Text Available Unprecedented alkylation of silyl enol ethers has been developed by the use of ortho-alkynylbenzoic acid alkyl esters as alkylating agents in the presence of a gold catalyst. The reaction probably proceeds through the gold-induced in situ construction of leaving groups and subsequent nucleophilic attack on the silyl enol ethers. The generated leaving compound abstracts a proton to regenerate the silyl enol ether structure.

The 18F-labelled alkylating agent 2,2,2-trifluoroethyl triflate: synthesis and specific activity

International Nuclear Information System (INIS)

Johnstroem, P.; Stone-Elander, S.

1995-01-01

A method for synthesizing the alkylating agent 2,2,2-trifluoroethyl triflate labelled with [ 18 ]fluoride in the two position is presented. Ethyl [2- 18 )F]-trifluoroacetate was synthesized by the nucleophilic reaction of [ 18 F]F - with ethyl bromodifluoroacetate in DMSO (45-60%, 5 min, 80 o C) and subsequently converted to [2- 18 F]-2,2,2-trifluoroethanol using alane in THF (85-95%, 2 min, 40 o C. Reaction with triflic anhydride in 2,6-lutidine produced [2- 18 F]-2,2,2-trifluoroethyl triflate (70-80%, 1 min, 0 o C. In all three cases the product was removed from the reaction vessel by heating to distil under a stream of nitrogen. [2- 18 F]-2,2,2-Trifluoroethyl triflate was used to label 2-oxoquazepam by N-alkylation in a toulene:DMF mixture (80-85%, 20 min, 120 o C). Although no-carrier-added [ 18 )F]F - was used, considerable unlabelled ethyl trifluoroacetate was produced in the first reaction. Varying the conditions for the fluoro-debromination reaction did not appreciably improve the relative ratio of labelled to unlabelled ester. The specific activity of the labelled 1,4-benzodiazepine-2-one obtained from 1850 MBq [ 18 F]F - was found to be ≅37 MBq/μmol (1mCi/μmol). (Author)

Impact of gender on efficacy and acute toxicity of alkylating agent -based chemotherapy in Ewing sarcoma: secondary analysis of the Euro-Ewing99-R1 trial.

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van den Berg, Henk; Paulussen, Michael; Le Teuff, Gwénaël; Judson, Ian; Gelderblom, Hans; Dirksen, Uta; Brennan, Bernadette; Whelan, Jeremy; Ladenstein, Ruth Lydia; Marec-Berard, Perrine; Kruseova, Jarmila; Hjorth, Lars; Kühne, Thomas; Brichard, Benedicte; Wheatley, Keith; Craft, Alan; Juergens, Heribert; Gaspar, Nathalie; Le Deley, Marie-Cécile

2015-11-01

Based on the randomised Euro-EWING99-R1 trial, vincristine, adriamycin, cyclophosphamide (VAC) may be able to replace vincristine, adriamycin, ifosfamide (VAI) in the treatment of standard-risk Ewing sarcoma. However some heterogeneity of treatment effect by gender was observed. The current exploratory study aimed at investigating the influence of gender on treatment efficacy and acute toxicity. Impact of gender on event-free survival (EFS), acute toxicity by course, switches between treatment arms and cumulative dose of alkylating agents was evaluated in multivariable models adjusted for age including terms to test for heterogeneity of treatment effect by gender. The analysis of the EFS was performed on the intention-to-treat population. EFS did not significantly differ between the 509 males and 347 females (p=0.33), but an interaction in terms of efficacy was suspected between treatment and gender (p=0.058): VAC was associated with poorer EFS than VAI in males, hazard ratio (HR) (VAC/VAI)=1.37 [95% confidence interval (CI), 0.98-1.90], contrasting with HR=0.81 [95%CI, 0.53-1.24] in females. Severe toxicity was more frequent in females, whatever the toxicity type. Thirty patients switched from VAI to VAC (9/251 males, 4%, and 21/174 females, 12%) mostly due to renal toxicity, and three from VAC to VAI (2/258 males, 0.8%, and 1/173 females, 0.6%). A reduction of alkylating agent cumulative dose >20% was more frequent in females (15% versus 9%, p=0.005), with no major difference between VAC and VAI (10% versus 13%, p=0.15). Differences of acute toxicity rate and cumulative doses of alkylating agents could not explain the marginal interaction observed in the Euro-EWING99-R1 trial data. Effects of gender-dependent polymorphism/activity of metabolic enzymes (e.g. known for CYP2B6) of ifosfamide versus cyclophosphamide should be explored. External data are required to further evaluate whether there is heterogeneity of alkylating agent effect by gender. NCT00987636 and

Gadolinium and fluorescent bi-functionally labeling and in vitro MRI of rat bone marrow mesenchymal stem cells

International Nuclear Information System (INIS)

Shen Jun; Zhou Cuiping; Cheng Li'na; Duan Xiaohui; Liang Biling; Fu Yue; Bi Xiaobin; Liu Yu; Deng Yubin

2008-01-01

Objective: To determine the feasibility of magnetically labeling and tracking mesenchymal stem cells (MSCs) in vitro by using a gadolinium and fluorescent bi-functionally transfection agent of polyethylenimine. Methods: A gadolinium bifunctional transfection reagent complex was obtained after the linear polyethylenimine derivative (JetPEI-FluoR) was incubated with Gd-DTPA. Mesenchymal stem cells isolated from the bone marrows of SD rats were cultured and expanded. The mesenchymal stem cells were incubated with the bi-functional labeling agents. After labeling, the MSCs were examined with fluoroscope and electron microscope and the biological characters were detected including trypan blue exclusion test, MTT, and apoptosis detection. On a 1.5 T MR system, the labeled MSCs were examined with spin echo T 1 WI and T 2 WI and T 1 measurement with mixed sequence. After labeling, the cells were cultured and undergone routine passage. Prior MR examinations were repeated for each passage of labeled cells. All data was statistically prolessed with SPSS for Windows. Results: Of 5 x 10 5 MSCs incubated with the bi-functional agents, 4.25 x 10 5 MSCs were successfully labeled, the percentage of labeled MSCs was 85% fluoroscopically. The high density electron particles of gadolinium observed electron microscopically existed around cellular apparatuses, especially around Golgi apparatus. In trypan blue exclusion test, the exclusion rate of labeled MSCs with incubation duration of 3,6,12,24 h was (96.55±2.90)%, (94.17± 2.56)%, (97.16±3.12)% and (94.23±2.67)%, respectively. The corresponding exclusion rate of unlabeled MSCs was (95.86±2.67)%, (92.04±2.21)%, (93.38±3.64)% and (92.12±2.53)%, respectively. There was no statistical difference of trypan blue exclusion rate between labeled cells and control unlabeled cells within 24 hours of incubation (F=4.523, P>0.05). In the proliferation test, the optical absorption value of labeled MSC with 2.5, 5.0, 10.0, 20.0, 30.0 and 40

Effect of the antitumoral alkylating agent 3-bromopyruvate on mitochondrial respiration: role of mitochondrially bound hexokinase.

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Rodrigues-Ferreira, Clara; da Silva, Ana Paula Pereira; Galina, Antonio

2012-02-01

The alkylating agent 3-Bromopyruvate (3-BrPA) has been used as an anti-tumoral drug due to its anti-proliferative property in hepatomas cells. This propriety is believed to disturb glycolysis and respiration, which leads to a decreased rate of ATP synthesis. In this study, we evaluated the effects of the alkylating agent 3-BrPA on the respiratory states and the metabolic steps of the mitochondria of mice liver, brain and in human hepatocarcinoma cell line HepG2. The mitochondrial membrane potential (ΔΨ(m)), O(2) consumption and dehydrogenase activities were rapidly dissipated/or inhibited by 3-BrPA in respiration medium containing ADP and succinate as respiratory substrate. 3-BrPA inhibition was reverted by reduced glutathione (GSH). Respiration induced by yeast soluble hexokinase (HK) was rapidly inhibited by 3-BrPA. Similar results were observed using mice brain mitochondria that present HK naturally bound to the outer mitochondrial membrane. When the adenine nucleotide transporter (ANT) was blocked by the carboxyatractiloside, the 3-BrPA effect was significantly delayed. In permeabilized human hepatoma HepG2 cells that present HK type II bound to mitochondria (mt-HK II), the inhibiting effect occurred faster when the endogenous HK activity was activated by 2-deoxyglucose (2-DOG). Inhibition of mt-HK II by glucose-6-phosphate retards the mitochondria to react with 3-BrPA. The HK activities recovered in HepG2 cells treated or not with 3-BrPA were practically the same. These results suggest that mitochondrially bound HK supporting the ADP/ATP exchange activity levels facilitates the 3-BrPA inhibition reaction in tumors mitochondria by a proton motive force-dependent dynamic equilibrium between sensitive and less sensitive SDH in the electron transport system.

Alkylating chemotherapeutic agents cyclophosphamide and melphalan cause functional injury to human bone marrow-derived mesenchymal stem cells.

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Kemp, Kevin; Morse, Ruth; Sanders, Kelly; Hows, Jill; Donaldson, Craig

2011-07-01

The adverse effects of melphalan and cyclophosphamide on hematopoietic stem cells are well-known; however, the effects on the mesenchymal stem cells (MSCs) residing in the bone marrow are less well characterised. Examining the effects of chemotherapeutic agents on patient MSCs in vivo is difficult due to variability in patients and differences in the drug combinations used, both of which could have implications on MSC function. As drugs are not commonly used as single agents during high-dose chemotherapy (HDC) regimens, there is a lack of data comparing the short- or long-term effects these drugs have on patients post treatment. To help address these problems, the effects of the alkylating chemotherapeutic agents cyclophosphamide and melphalan on human bone marrow MSCs were evaluated in vitro. Within this study, the exposure of MSCs to the chemotherapeutic agents cyclophosphamide or melphalan had strong negative effects on MSC expansion and CD44 expression. In addition, changes were seen in the ability of MSCs to support hematopoietic cell migration and repopulation. These observations therefore highlight potential disadvantages in the use of autologous MSCs in chemotherapeutically pre-treated patients for future therapeutic strategies. Furthermore, this study suggests that if the damage caused by chemotherapeutic agents to marrow MSCs is substantial, it would be logical to use cultured allogeneic MSCs therapeutically to assist or repair the marrow microenvironment after HDC.

Determination of alkylation of bacterial DNA as a rapid test for toxicological evaluation of alkylating xenobiotic agents

Energy Technology Data Exchange (ETDEWEB)

Botzenhart, K.; Waldner-Sander, S.; Schweinsberg, F.

1986-05-01

Alkylated purine bases from hydrolized DNA can be separated by HPLC and quantified with a fluorescence detector. We applied this method to bacterial DNA. 7-methylguanine was detected after treatment of Serratia marcescens with iodoacetamide, dimethyl sulfate and with polluted air.

The adaptive response of E. coli to low levels of alkylating agent

International Nuclear Information System (INIS)

Jeggo, P.; Defais, M.; Samson, L.; Schendel, P.

1978-01-01

In an attempt to characterise which gene products may be involved in the repair system induced in E. coli by growth on low levels of alkylating agent (the adaptive response) we have analysed mutants deficient in other known pathways of DNA repair for the ability to adapt to MNNG. Adaptive resistance to the killing effects of MNNG seems to require a functional DNA polymerase I whereas resistance to the mutagenic effects can occur in polymerase I deficient strains; similarly killing adaptation could not be observed in a dam3 mutant, which was nonetheless able to show mutational adaptation. These results suggest that these two parts of the adaptive response must, at least to some extent, be separable. Both adaptive responses can be seen in the absence of uvrD + uvrE + -dependent mismatch repair, DNA polymerase II activity, or recF-mediated recombination and they are not affected by decreased levels of adenyl cyclase. The data presented support our earlier conclusion that adaptive resistance to the killing and mutagenic effect of MNNG is the result of previously uncharacterised repair pathways. (orig.) [de

E. coli mismatch repair enhances AT-to-GC mutagenesis caused by alkylating agents.

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Nakano, Kota; Yamada, Yoko; Takahashi, Eizo; Arimoto, Sakae; Okamoto, Keinosuke; Negishi, Kazuo; Negishi, Tomoe

2017-03-01

Alkylating agents are known to induce the formation of O 6 -alkylguanine (O 6 -alkG) and O 4 -alkylthymine (O 4 -alkT) in DNA. These lesions have been widely investigated as major sources of mutations. We previously showed that mismatch repair (MMR) facilitates the suppression of GC-to-AT mutations caused by O 6 -methylguanine more efficiently than the suppression of GC-to-AT mutations caused by O 6 -ethylguanine. However, the manner by which O 4 -alkyT lesions are repaired remains unclear. In the present study, we investigated the repair pathway involved in the repair of O 4 -alkT. The E. coli CC106 strain, which harbors Δprolac in its genomic DNA and carries the F'CC106 episome, can be used to detect AT-to-GC reverse-mutation of the gene encoding β-galactosidase. Such AT-to-GC mutations should be induced through the formation of O 4 -alkT at AT base pairs. As expected, an O 6 -alkylguanine-DNA alkyltransferase (AGT) -deficient CC106 strain, which is defective in both ada and agt genes, exhibited elevated mutant frequencies in the presence of methylating agents and ethylating agents. However, in the UvrA-deficient strain, the methylating agents were less mutagenic than in wild-type, while ethylating agents were more mutagenic than in wild-type, as observed with agents that induce O 6 -alkylguanine modifications. Unexpectedly, the mutant frequencies decreased in a MutS-deficient strain, and a similar tendency was observed in MutL- or MutH-deficient strains. Thus, MMR appears to promote mutation at AT base pairs. Similar results were obtained in experiments employing double-mutant strains harboring defects in both MMR and AGT, or MMR and NER. E. coli MMR enhances AT-to-GC mutagenesis, such as that caused by O 4 -alkylthymine. We hypothesize that the MutS protein recognizes the O 4 -alkT:A base pair more efficiently than O 4 -alkT:G. Such a distinction would result in misincorporation of G at the O 4 -alkT site, followed by higher mutation frequencies in wild

Conformational change in human DNA repair enzyme O6-methylguanine-DNA methyltransferase upon alkylation of its active site by SN1 (indirect-acting) and SN2 (direct-acting) alkylating agents: breaking a "salt-link".

Science.gov (United States)

Oh, H K; Teo, A K; Ali, R B; Lim, A; Ayi, T C; Yarosh, D B; Li, B F

1996-09-24

Human O6-methylguanine-DNA methyltransferase (MGMT) repairs DNA by transferring alkyl (R-) adducts from O6-alkylguanine (6RG) in DNA to its own cysteine residue at codon 145 (formation of R-MGMT). We show here that R-MGMT in cell extracts, which is sensitive to protease V8 cleavage at the glutamic acid residues at codons 30 (E30) and 172 (E172), can be specifically immunoprecipitated with an MGMT monoclonal antibody, Mab.3C7. This Mab recognizes an epitope of human MGMT including the lysine 107 (K107) which is within the most basic region that is highly conserved among mammalian MGMTs. Surprisingly, the K107L mutant protein is repair-deficient and readily cleaved by protease V8 similar to R-MGMT. We propose that R-MGMT adopted an altered conformation which exposed the Mab.3C7 epitope and rendered that protein sensitive to protease V8 attack. This proposal could be explained by the disruption of a structural "salt-link" within the molecule based on the available structural and biochemical data. The specific binding of Mab.3C7 to R-MGMT has been compared with the protease V8 method in the detection of R-MGMT in extracts of cells treated with low dosages of methyliodide (SN2) and O6-benzylguanine. Their identical behaviors in producing protease V8 sensitive R-MGMT and Mab.3C7 immunoprecipitates suggest that probably methyl iodide (an ineffective agent in producing 6RG in DNA) can directly alkylate the active site of cellular MGMT similar to O6-benzylguanine. The effectiveness of MeI in producing R-MGMT, i.e., inactivation of cellular MGMT, indicates that this agent can increase the effectiveness of environmental and endogenously produced alkylating carcinogens in producing the mutagenic O6-alkylguanine residues in DNA in vivo.

Atorvastatin Downregulates In Vitro Methyl Methanesulfonate and Cyclophosphamide Alkylation-Mediated Cellular and DNA Injuries

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Carlos F. Araujo-Lima

2018-01-01

Full Text Available Statins are 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA reductase inhibitors, and this class of drugs has been studied as protective agents against DNA damages. Alkylating agents (AAs are able to induce alkylation in macromolecules, causing DNA damage, as DNA methylation. Our objective was to evaluate atorvastatin (AVA antimutagenic, cytoprotective, and antigenotoxic potentials against DNA lesions caused by AA. AVA chemopreventive ability was evaluated using antimutagenicity assays (Salmonella/microsome assay, cytotoxicity, cell cycle, and genotoxicity assays in HepG2 cells. The cells were cotreated with AVA and the AA methyl methanesulfonate (MMS or cyclophosphamide (CPA. Our datum showed that AVA reduces the alkylation-mediated DNA damage in different in vitro experimental models. Cytoprotection of AVA at low doses (0.1–1.0 μM was observed after 24 h of cotreatment with MMS or CPA at their LC50, causing an increase in HepG2 survival rates. After all, AVA at 10 μM and 25 μM had decreased effect in micronucleus formation in HepG2 cells and restored cell cycle alterations induced by MMS and CPA. This study supports the hypothesis that statins can be chemopreventive agents, acting as antimutagenic, antigenotoxic, and cytoprotective components, specifically against alkylating agents of DNA.

Light of DNA-alkylating agents in castration-resistant prostate cancer cells: a novel mixed EGFR/DNA targeting combi-molecule.

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Liang, Guan-Can; Zheng, Hao-Feng; Chen, Yan-Xiong; Li, Teng-Cheng; Liu, Wei; Fang, You-Qiang

2017-01-01

The mechanism underlying the therapeutic effects of combi-molecule JDF12 on prostate cancer (PCa) DU145 cells remains still unclear. This study aimed to investigate the proteomic profile after JDF12 treatment in DU145 cells by comparing with that in Iressa treated cells and untreated cells. MTT was used to evaluate drug cytotoxicity, DAPI staining was done to assess apoptosis of cells, and flow cytometry was used to analyze cell cycle. iTRAQ and qPCR were employed to obtain the proteomic profiles of JDF12 treated, Iressa treated, and untreated DU145 cells, and validate the expression of selected differentially expressed proteins, respectively. JDF12 could significantly inhibit the proliferation and increase the apoptosis of DU145 cells when compared with Iressa or blank group. In total, 5071 proteins were obtained, out of which, 42, including 21 up-regulated and 21 down-regulated proteins, were differentially expressed in JDF12 group when compared with Iressa and blank groups. The up-regulated proteins were mainly involved in DNA damage/repair and energy metabolism; while the down-regulated proteins were mainly associated with cell apoptosis. qPCR confirmed the expression of several biologically important proteins in DU145 cells after JDF12 treatment. The molecular mechanisms of DNA alkylating agents on PCa therapy that with the assistant of EGFR-blocker were revealed on proteomic level, which may increase the possible applications of DNA alkylating agents and JDF12 on PCa therapy.

[Sensitivity of the splenic immunocompetent cells of mice with different genotypes to the action of alkylating agents].

Science.gov (United States)

Pevnitskiĭ, L A; Telegin, L Iu; Ir, K N

1985-08-01

It has been established in experiments in vitro that splenocytes of DBA/2GSto mice are more sensitive to the immunosuppressant action of the alkylating agents (cyclophosphamide, sarcolysine and thiophosphamide) than splenocytes of BALB/cGLacSto mice. Splenocytes of C3H/SnRap mice exhibit and intermediate type of sensitivity. T-lymphocytes of the spleen of BALB/cGLacSto and DBA/2GSto mice are more sensitive in vitro to the action of active metabolites of cyclophosphamide as compared to B-lymphocytes, with both types of the cells of DBA/2GSto mice being affected to a greater extent than the cells of BALB/cGLacSto mice.

Kinetics of micronucleus induction and cytotoxicity caused by distinct antineoplastics and alkylating agents in vivo.

Science.gov (United States)

Morales-Ramírez, Pedro; Vallarino-Kelly, Teresita; Cruz-Vallejo, Virginia

2014-01-30

This mini-review aims to compare the differences in the kinetics of the induction of micronucleated polychromatic erythrocytes (MN-PCE) and cytotoxicity by distinct antineoplastic and genotoxic agents in murine peripheral blood in vivo and to correlate these kinetics with the underlying processes. Comparisons were carried out using our previously obtained data with nominal doses causing similar levels of cytotoxicity, as measured in terms reduction of PCE. The aneuploidogens caused the most rapid induction of MN-PCEs and had the highest rates of cytotoxicity and genotoxicity. The promutagens cyclophosphamide and dimethylnitrosamine showed the most delayed responses and had the lowest genotoxic and cytotoxic efficiencies. DNA crosslinking agents had a similar delay of 4-5 h, greater than those of aneuploidogens, but differed in their cytotoxic and genotoxic efficiencies. Methylnitrosourea and 5-aza-cytidine caused greater delays than crosslinking agents. These delays can be due to the methylnitrosourea-mediated induction of formation of mono alkyl adducts which are interpreted as mismatches during DNA duplication, whereas 5-aza-cytidine requires incorporation into the DNA to induce breakage. This review allows us to conclude that the requirement for metabolic activation and the mechanisms of DNA breakage and of micronucleus induction are the main factors that affect the time of maximal MN-PCE induction. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Determination of methyl-, 2-hydroxyethyl- and 2-cyanoethylmercapturic acids as biomarkers of exposure to alkylating agents in cigarette smoke.

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Scherer, Gerhard; Urban, Michael; Hagedorn, Heinz-Werner; Serafin, Richard; Feng, Shixia; Kapur, Sunil; Muhammad, Raheema; Jin, Yan; Sarkar, Mohamadi; Roethig, Hans-Juergen

2010-10-01

Alkylating agents occur in the environment and are formed endogenously. Tobacco smoke contains a variety of alkylating agents or precursors including, among others, N-nitrosodimethylamine (NDMA), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), acrylonitrile and ethylene oxide. We developed and validated a method for the simultaneous determination of methylmercapturic acid (MMA, biomarker for methylating agents such as NDMA and NNK), 2-hydroxyethylmercapturic acid (HEMA, biomarker for ethylene oxide) and 2-cyanoethylmercapturic acid (CEMA, biomarker for acrylonitrile) in human urine using deuterated internal standards of each compound. The method involves liquid/liquid extraction of the urine sample, solid phase extraction on anion exchange cartridges, derivatization with pentafluorobenzyl bromide (PFBBr), liquid/liquid extraction of the reaction mixture and LC-MS/MS analysis with positive electrospray ionization. The method was linear in the ranges of 5.00-600, 1.00-50.0 and 1.50-900 ng/ml for MMA, HEMA and CEMA, respectively. The method was applied to two clinical studies in adult smokers of conventional cigarettes who either continued smoking conventional cigarettes, were switched to test cigarettes consisting of either an electrically heated cigarette smoking system (EHCSS) or having a highly activated carbon granule filter that were shown to have reduced exposure to specific smoke constituents, or stopped smoking. Urinary excretion of MMA was found to be unaffected by switching to the test cigarettes or stop smoking. Urinary HEMA excretion decreased by 46 to 54% after switching to test cigarettes and by approximately 74% when stopping smoking. Urinary CEMA excretion decreased by 74-77% when switching to test cigarettes and by approximately 90% when stopping smoking. This validated method for urinary alkylmercapturic acids is suitable to distinguish differences in exposure not only between smokers and nonsmokers but also between smoking of conventional and

Safety Assessment of Amino Acid Alkyl Amides as Used in Cosmetics.

Science.gov (United States)

Burnett, Christina L; Heldreth, Bart; Bergfeld, Wilma F; Belsito, Donald V; Hill, Ronald A; Klaassen, Curtis D; Liebler, Daniel C; Marks, James G; Shank, Ronald C; Slaga, Thomas J; Snyder, Paul W; Andersen, F Alan

The Cosmetic Ingredient Review Expert Panel (Panel) reviewed the product use, formulation, and safety data of 115 amino acid alkyl amides, which function as skin and hair conditioning agents and as surfactants-cleansing agents in personal care products. Safety test data on dermal irritation and sensitization for the ingredients with the highest use concentrations, lauroyl lysine and sodium lauroyl glutamate, were reviewed and determined to adequately support the safe use of the ingredients in this report. The Panel concluded that amino acid alkyl amides are safe in the present practices of use and concentration in cosmetics, when formulated to be nonirritating.

Sensitization to radiation and alkylating agents by inhibitors of poly(ADP-ribose) polymerase is enhanced in cells deficient in DNA double-strand break repair.

Science.gov (United States)

Löser, Dana A; Shibata, Atsushi; Shibata, Akiko K; Woodbine, Lisa J; Jeggo, Penny A; Chalmers, Anthony J

2010-06-01

As single agents, chemical inhibitors of poly(ADP-ribose) polymerase (PARP) are nontoxic and have clinical efficacy against BRCA1- and BRCA2-deficient tumors. PARP inhibitors also enhance the cytotoxicity of ionizing radiation and alkylating agents but will only improve clinical outcomes if tumor sensitization exceeds effects on normal tissues. It is unclear how tumor DNA repair proficiency affects the degree of sensitization. We have previously shown that the radiosensitizing effect of PARP inhibition requires DNA replication and will therefore affect rapidly proliferating tumors more than normal tissues. Because many tumors exhibit defective DNA repair, we investigated the impact of double-strand break (DSB) repair integrity on the sensitizing effects of the PARP inhibitor olaparib. Sensitization to ionizing radiation and the alkylating agent methylmethane sulfonate was enhanced in DSB repair-deficient cells. In Artemis(-/-) and ATM(-/-) mouse embryo fibroblasts, sensitization was replication dependent and associated with defective repair of replication-associated damage. Radiosensitization of Ligase IV(-/-) mouse embryo fibroblasts was independent of DNA replication and is explained by inhibition of "alternative" end joining. After methylmethane sulfonate treatment, PARP inhibition promoted replication-independent accumulation of DSB, repair of which required Ligase IV. Our findings predict that the sensitizing effects of PARP inhibitors will be more pronounced in rapidly dividing and/or DNA repair defective tumors than normal tissues and show their potential to enhance the therapeutic ratio achieved by conventional DNA-damaging agents.

Isobutane alkylation over solid catalysts

Energy Technology Data Exchange (ETDEWEB)

Kozorezov, Y.I.; Lisin, V.I.

1979-05-01

Commercial alumina modified with 6Vertical Bar3< by wt boron trifluoride was active in isobutane alkylation with ethylene in a flow reactor at 5:1 isobutane-ethylene and 5-20 min reaction time. The reaction rate was first-order in ethylene and increased with increasing temperature (20/sup 0/-80/sup 0/C) and ethylene pressure (0.2-3 atm). The calculated activation energy was 8.4 kj. Kinetic data and the activity of tert.-butyl chloride, but not ethyl chloride as alkylating agents in place of ethylene suggested a carbonium-ion chain mechanism involving both surface and gas-phase reactions. The ethylene-based yield of the alkylate decreased from 132 to 41Vertical Bar3< by wt after nine hours on stream, and its bromine number increased from 0.2 to 1 g Br/sub 2//100 ml. This inhibition was attributed to adsorption on the active acidic sites of the reaction products, particularly C/sub 10//sup +/ olefins. Catalyst stabilization could probably be achieved by selecting an appropriate solvent that would continuously desorb the inhibiting products from the catalyst surface.

Alkyl chitosan film-high strength, functional biomaterials.

Science.gov (United States)

Lu, Li; Xing, Cao; Xin, Shen; Shitao, Yu; Feng, Su; Shiwei, Liu; Fusheng, Liu; Congxia, Xie

2017-11-01

Biofilm with strong tensile strength is a topic item in the area of tissue engineering, medicine engineering, and so forth. Here we introduced an alkyl chitosan film with strong tensile strength and its possibility for an absorbable anticoagulation material in vivo was tested in the series of blood test, such as dynamic coagulation time, plasma recalcification time and hemolysis. Alkyl chitosan film was a better biomaterial than traditional chitosan film in the anticoagulation, tissue compatibility and cell compatibility. The unique trait of alkyl chitosan film may be for its greater contact angle and hydrophobicity ability to reduce the adsorption capacity for the blood component and the activity of fibrinolytic enzymes, enhance the antibacterial capacity than chitosan film. Moreover, none of chitosan film or butyl chitosan film exhibited quick inflammation or other disadvantage and degraded quickly by implanted test. Therefore, Alkyl chitosan film is of prospective properties as an implantable, absorbable agent for tissue heals, and this material need further research. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3034-3041, 2017. © 2017 Wiley Periodicals, Inc.

Investigating the heterogeneity of alkylating agents' efficacy and toxicity between sexes: A systematic review and meta-analysis of randomized trials comparing cyclophosphamide and ifosfamide (MAIAGE study)

NARCIS (Netherlands)

Fresneau, Brice; Hackshaw, A.; Hawkins, D. S.; Paulussen, M.; Anderson, J. R.; Judson, I.; Litière, S.; Dirksen, U.; Lewis, I.; van den Berg, H.; Gaspar, N.; Gelderblom, H.; Whelan, J.; Boddy, A. V.; Wheatley, K.; Pignon, J. P.; de Vathaire, F.; Le Deley, M. C.; Le Teuff, G.

2017-01-01

A marginal interaction between sex and the type of alkylating agent was observed for event-free survival in the Euro-EWING99-R1 randomized controlled trial (RCT) comparing cyclophosphamide and ifosfamide in Ewing sarcoma. To further evaluate this interaction, we performed an individual patient data

Chiral 2-Aminobenzimidazole as Bifunctional Catalyst in the Asymmetric Electrophilic Amination of Unprotected 3-Substituted Oxindoles

Directory of Open Access Journals (Sweden)

Llorenç Benavent

2018-06-01

Full Text Available The use of readily available chiral trans-cyclohexanediamine-benzimidazole derivatives as bifunctional organocatalysts in the asymmetric electrophilic amination of unprotected 3-substituted oxindoles is presented. Different organocatalysts were evaluated; the most successful one contained a dimethylamino moiety (5. With this catalyst under optimized conditions, different oxindoles containing a wide variety of substituents at the 3-position were aminated in good yields and with good to excellent enantioselectivities using di-tert-butylazodicarboxylate as the aminating agent. The procedure proved to be also efficient for the amination of 3-substituted benzofuranones, although with moderate results. A bifunctional role of the catalyst, acting as Brønsted base and hydrogen bond donor, is proposed according to the experimental results observed.

In vitro testing of drug combinations employing nilotinib and alkylating agents with regard to pretransplant conditioning treatment of advanced-phase chronic myeloid leukemia.

Science.gov (United States)

Radujkovic, Aleksandar; Luft, Thomas; Dreger, Peter; Ho, Anthony D; Jens Zeller, W; Fruehauf, Stefan; Topaly, Julian

2014-08-01

The prognosis of patients with advanced-phase chronic myeloid leukemia (CML) remains dismal despite the availability of targeted therapies and allogeneic stem cell transplantation (allo-SCT). Increasing the antileukemic efficacy of the pretransplant conditioning regimen may be a strategy to increase remission rates and duration. We therefore investigated the antiproliferative effects of nilotinib in combination with drugs that are usually used for conditioning: the alkylating agents mafosfamide, treosulfan, and busulfan. Drug combinations were tested in vitro in different imatinib-sensitive and imatinib-resistant BCR-ABL-positive cell lines. A tetrazolium-based MTT assay was used for the assessment and quantification of growth inhibition after exposure to alkylating agents alone or to combinations with nilotinib. Drug interaction was analyzed using the median-effect method of Chou and Talalay, and combination index (CI) values were calculated according to the classic isobologram equation. Treatment of imatinib-sensitive, BCR-ABL-positive K562 and LAMA84 cells with nilotinib in combination with mafosfamide, treosulfan, or busulfan resulted in synergistic (CI 1) effects, respectively. In imatinib-resistant K562-R and LAMA84-R cells, all applied drug combinations were synergistic (CI conditioning regimens for allo-SCT in advanced-phase CML.

Noncanonical regulation of alkylation damage resistance by the OTUD4 deubiquitinase.

Science.gov (United States)

Zhao, Yu; Majid, Mona C; Soll, Jennifer M; Brickner, Joshua R; Dango, Sebastian; Mosammaparast, Nima

2015-06-12

Repair of DNA alkylation damage is critical for genomic stability and involves multiple conserved enzymatic pathways. Alkylation damage resistance, which is critical in cancer chemotherapy, depends on the overexpression of alkylation repair proteins. However, the mechanisms responsible for this upregulation are unknown. Here, we show that an OTU domain deubiquitinase, OTUD4, is a positive regulator of ALKBH2 and ALKBH3, two DNA demethylases critical for alkylation repair. Remarkably, we find that OTUD4 catalytic activity is completely dispensable for this function. Rather, OTUD4 is a scaffold for USP7 and USP9X, two deubiquitinases that act directly on the AlkB proteins. Moreover, we show that loss of OTUD4, USP7, or USP9X in tumor cells makes them significantly more sensitive to alkylating agents. Taken together, this work reveals a novel, noncanonical mechanism by which an OTU family deubiquitinase regulates its substrates, and provides multiple new targets for alkylation chemotherapy sensitization of tumors. © 2015 The Authors.

One-electron reduction of 2- and 6-methyl-1,4-naphthoquinone bioreductive alkylating agents

International Nuclear Information System (INIS)

Wilson, I.; Wardman, P.; Lin, T.S.; Sartorelli, A.C.

1986-01-01

The semiquinones, Q.-, of derivatives of 2- and 6-methyl-1,4-naphthoquinones, some incorporating leaving groups with substituents such as CH 2 Br or CH 2 OCONHCH 3 , have been produced by radiolytic reduction of Q by (CH 3 )2COH radicals. The absorption spectra and decay kinetics of Q.- were all closely similar to that produced from 2-methyl-1,4-naphthoquinone, with no evidence for unimolecular elimination of a leaving group in the semiquinone form, but immediate loss of leaving group upon two-electron reduction of Q to the hydroquinone. The redox equilibria between Q/Q.- and O2/O2.- were characterized, and reduction potentials of the couples Q/Q.- in water at pH 7.6 were calculated. The implications of these observations for the use of these compounds as bioreductive alkylating agents or as radiosensitizers with potential selective activity toward hypoxic cells are discussed

Synthesis of alkylated deoxyno irimycin and 1,5-dideoxy-1,5-iminoxylitol analogues:

DEFF Research Database (Denmark)

Szczepina, M.G.; Johnston, B.D; Yuan, Y.

2004-01-01

The syntheses of N-alkylated deoxynojirimycin and 1,5-dideoxy-1,5-iminoxylitol derivatives having either a D- or an L-erythritol-3-sulfate functionalized N-substituent are reported. The alkylating agent used was a cyclic sulfate derivative, whereby selective attack of the nitrogen atom at the least...

Novel bifunctional anthracycline and nitrosourea chemotherapy for human bladder cancer: analysis in a preclinical survival model.

Science.gov (United States)

Glaves, D; Murray, M K; Raghavan, D

1996-08-01

A hybrid drug [N-2-chloroethylnitrosoureidodaunorubicin (AD312)] that combines structural and functional features of both anthracyclines and nitrosoureas was evaluated in a preclinical survival model of human bladder cancer. To measure the therapeutic activity of AD312, UCRU-BL13 transitional cell carcinoma cells were grown as xenografts in nude mice, and tumor growth rates were compared after i.v. administration of the drug at three dose levels. AD312 treatment at 45 and 60 mg/kg achieved 7-10-fold inhibition of tumor growth and increased host survival by 156 and 249%, respectively. Doses of 60 mg/kg showed optimal therapeutic efficacy, with sustained tumor growth inhibition, an over 2-fold increase in life span, and 40% of mice tumor free ("cured") at 120 days. Tumors were unresponsive to maximum tolerated doses of doxorubicin, a standard anthracycline used as a single agent and in combination therapies for bladder cancer. 1,3-Bis-[2-chloroethyl]-1-nitrosourea was used as a control for the apparently enhanced response of human tumors in murine hosts to nitrosoureas. 1, 3-Bis-[2-chloroethyl]-1-nitrosourea administered in three injections of 20 mg/kg did not cure mice but temporarily inhibited tumor growth by 70% and prolonged survival by 55%; its activity in this model suggests that it may be included in the repertoire of alkylating agents currently used for treatment of bladder cancers. AD312 showed increased antitumor activity with less toxicity than doxorubicin, and its bifunctional properties provide the opportunity for simultaneous treatment of individual cancer cells with two cytotoxic modalities as well as treatment of heterogeneous populations typical of bladder cancers. This novel cytotoxic drug cured doxorubicin-refractory disease and should be investigated for the clinical management of bladder cancer.

Interstrand cross-linking of DNA by 1,3-bis(2-chloroethyl)-1-nitrosourea and other 1-(2-haloethyl)-1-nitrosoureas.

Science.gov (United States)

Kohn, K W

1977-05-01

Bifunctional alkylating agents are known to cross-link DNA by simultaneously alkylating two guanine residues located on opposite strands. Despite this apparent requirement for bifunctionality, 1-(2-chloroethyl)-1-nitrosoureas bearing a single alkylating function were found to cross-link DNA in vitro. Cross-linking was demonstrated by showing inhibition of alkali-induced strand separation. Extensive cross-linking was observed in DNA treated with 1-(2-chloroethyl)-1-nitrosourea, 1,3-bis-(2-chloroethyl)-1-nitrosourea, and 1-(2-chloroethyl(-3-cyclohexyl-1-nitrosourea. The reaction occurs in two steps, an intital binding followed by a second step which can proceed after removal of unbound drug. It is suggested that the first step is chloroethylation of a nucleophilic site on one strand and that the second step involves displacement of Cl- by a nucleophilic site on the opposite strand, resulting in an ethyl bridge between the strands. Consistent with this possibility, 1-(2-fluoroethyl)-3-cyclohexyl-1-nitrosourea produced much less cross-linking, as expected from the known low activity of F-, compared with Cl-, as leaving group. 1-Methyl-1-nitrosourea, which is known to depurinate DNA, produced no detectable cross-linking.

Alkylation of human hair keratin for tunable hydrogel erosion and drug delivery in tissue engineering applications.

Science.gov (United States)

Han, Sangheon; Ham, Trevor R; Haque, Salma; Sparks, Jessica L; Saul, Justin M

2015-09-01

Polymeric biomaterials that provide a matrix for cell attachment and proliferation while achieving delivery of therapeutic agents are an important component of tissue engineering and regenerative medicine strategies. Keratins are a class of proteins that have received attention for numerous tissue engineering applications because, like other natural polymers, they promote favorable cell interactions and have non-toxic degradation products. Keratins can be extracted from various sources including human hair, and they are characterized by a high percentage of cysteine residues. Thiol groups on reductively extracted keratin (kerateine) form disulfide bonds, providing a more stable cross-linked hydrogel network than oxidatively extracted keratin (keratose) that cannot form disulfide crosslinks. We hypothesized that an iodoacetamide alkylation (or "capping") of cysteine thiol groups on the kerateine form of keratin could be used as a simple method to modulate the levels of disulfide crosslinking in keratin hydrogels, providing tunable rates of gel erosion and therapeutic agent release. After alkylation, the alkylated kerateines still formed hydrogels and the alkylation led to changes in the mechanical and visco-elastic properties of the materials consistent with loss of disulfide crosslinking. The alkylated kerateines did not lead to toxicity in MC3T3-E1 pre-osteoblasts. These cells adhered to keratin at levels comparable to fibronectin and greater than collagen. Alkylated kerateine gels eroded more rapidly than non-alkylated kerateine and this control over erosion led to tunable rates of delivery of rhBMP-2, rhIGF-1, and ciprofloxacin. These results demonstrate that alkylation of kerateine cysteine residues provides a cell-compatible approach to tune rates of hydrogel erosion and therapeutic agent release within the context of a naturally-derived polymeric system. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

O6-methylguanine-DNA methyltransferase activity is associated with response to alkylating agent therapy and with MGMT promoter methylation in glioblastoma and anaplastic glioma

Science.gov (United States)

Bobola, Michael S.; Alnoor, Mohammad; Chen, John Y.-S.; Kolstoe, Douglas D.; Silbergeld, Daniel L.; Rostomily, Robert C.; Blank, A.; Chamberlain, Marc C.; Silber, John R.

2014-01-01

Background CpG methylation in the O6-methylguanine-DNA methyltransferase (MGMT) promoter is associated with better outcome following alkylating agent chemotherapy in glioblastoma (GBM) and anaplastic glioma (AG). To what extent improved response reflects low or absent MGMT activity in glioma tissue has not been unequivocally assessed. This information is central to developing anti-resistance therapies. Methods We examined the relationship of MGMT activity in 91 GBMs and 84 AGs with progression-free survival (PFS) following alkylator therapy and with promoter methylation status determined by methylation-specific PCR (MSP). Results Cox regression analysis revealed that GBMs with high activity had a significantly greater risk for progression in dichotomous (P ≤ 0.001) and continuous (P ≤ 0.003) models, an association observed for different alkylator regimens, including concurrent chemo-radiation with temozolomide. Analysis of MGMT promoter methylation status in 47 of the GBMs revealed that methylated tumors had significantly lower activity (P ≤ 0.005) and longer PFS (P ≤ 0.036) compared to unmethylated tumors, despite overlapping activities. PFS was also significantly greater in methylated vs. unmethylated GBMs with comparable activity (P ≤ 0.005), and among unmethylated tumors with less than median activity (P ≤ 0.026), suggesting that mechanisms in addition to MGMT promote alkylator resistance. Similar associations of MGMT activity with PFS and promoter methylation status were observed for AGs. Conclusions Our results provide strong support for the hypotheses that MGMT activity promotes alkylator resistance and reflects promoter methylation status in malignant gliomas. General significance MGMT activity is an attractive target for anti-resistance therapy regardless of methylation status. PMID:25558448

ALKBH7 drives a tissue and sex-specific necrotic cell death response following alkylation-induced damage

Science.gov (United States)

Jordan, Jennifer J; Chhim, Sophea; Margulies, Carrie M; Allocca, Mariacarmela; Bronson, Roderick T; Klungland, Arne; Samson, Leona D; Fu, Dragony

2017-01-01

Regulated necrosis has emerged as a major cell death mechanism in response to different forms of physiological and pharmacological stress. The AlkB homolog 7 (ALKBH7) protein is required for regulated cellular necrosis in response to chemotherapeutic alkylating agents but its role within a whole organism is unknown. Here, we show that ALKBH7 modulates alkylation-induced cellular death through a tissue and sex-specific mechanism. At the whole-animal level, we find that ALKBH7 deficiency confers increased resistance to MMS-induced toxicity in male but not female mice. Moreover, ALKBH7-deficient mice exhibit protection against alkylation-mediated cytotoxicity in retinal photoreceptor and cerebellar granule cells, two cell types that undergo necrotic death through the initiation of the base excision repair pathway and hyperactivation of the PARP1/ARTD1 enzyme. Notably, the protection against alkylation-induced cerebellar degeneration is specific to ALKBH7-deficient male but not female mice. Our results uncover an in vivo role for ALKBH7 in mediating a sexually dimorphic tissue response to alkylation damage that could influence individual responses to chemotherapies based upon alkylating agents. PMID:28726787

Heterofacial alkylation of alkylenediamines by higher alkyl halides

International Nuclear Information System (INIS)

Semenov, V.A.; Kryshko, G.M.; Sokal'skaya, L.I.; Zhukova, N.G.

1985-01-01

A study of the physiochemical properties of alkylenediamines substituted by lower alkyls, showed that they possess increased complex-forming ability with respect to salts of different metals as titanium, niobium, zirconium, molybdenum, and zinc. To create a simpler method of synthesis of higher tetraaklyalkylalklyenediamines, based on the use of the accessible domestic raw material, the authors investigated the reaction of alkylenediamines with various alkyl halides. It was established that the best reagents can be obtained using alkyl bromides. It is concluded that the procedure of alkylation of alkylenediamines by higher alkyl halides in the presence of water developed permits the production of terraalkylalkylenediamines in one step with good yield and with purity acceptable for use as extraction reagents

Synthesis of a novel bicyclic bifunctional chelating agent

International Nuclear Information System (INIS)

Sweet, M.P.; Mease, R.C.; Joshi, V.; Srivastava, S.C.

1994-01-01

Semi-rigid ligands such as cyclohexyl EDTA (CDTA) and 4-isothiocyanato-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid (4-ICE) form chelates that are more stable in vivo compared to those of EDTA or DTPA. The authors have synthesized a new class of ligands in which the metal-binding polyaminocarboxylate groups are incorporated onto the rigid bicyclo[2.2.2]octane ring system. These ligands are expected to contribute to even higher in vivo stability of radiometal complexes. The synthesis of the first in this series of ligands (2.3-diaminobicyclo[2.2.2]octane-N,N,N',N'-tetraacetic acid, BODTA) began with a Diels-Alder reaction of 1,3-diacetylimidazolin-2-one and 1,3-cyclohexadiene. Base hydrolysis afforded the diamine. Following alkylation of the diamine with ethyl iodoacetate and hydrogenation of the double bond, hydrolysis of the esters gave BODTA. For initial conjugation with proteins, an average of one carboxylic acid of BODTA was converted into an NHS ester. In vivo testing of radioimmunoconjugates, prepared using this method, is in progress

Cell tracking with gadophrin-2: a bifunctional contrast agent for MR imaging, optical imaging, and fluorescence microscopy

International Nuclear Information System (INIS)

Daldrup-Link, Heike E.; Rudelius, Martina; Piontek, Guido; Schlegel, Juergen; Metz, Stephan; Settles, Marcus; Rummeny, Ernst J.; Pichler, Bernd; Heinzmann, Ulrich; Oostendorp, Robert A.J.

2004-01-01

The purpose of this study was to assess the feasibility of use of gadophrin-2 to trace intravenously injected human hematopoietic cells in athymic mice, employing magnetic resonance (MR) imaging, optical imaging (OI), and fluorescence microscopy. Mononuclear peripheral blood cells from GCSF-primed patients were labeled with gadophrin-2 (Schering AG, Berlin, Germany), a paramagnetic and fluorescent metalloporphyrin, using established transfection techniques with cationic liposomes. The labeled cells were evaluated in vitro with electron microscopy and inductively coupled plasma atomic emission spectrometry. Then, 1 x 10 6 -3 x 10 8 labeled cells were injected into 14 nude Balb/c mice and the in vivo cell distribution was evaluated with MR imaging and OI before and 4, 24, and 48 h after intravenous injection (p.i.). Five additional mice served as controls: three mice were untreated controls and two mice were investigated after injection of unlabeled cells. The contrast agent effect was determined quantitatively for MR imaging by calculating signal-to-noise-ratio (SNR) data. After completion of in vivo imaging studies, fluorescence microscopy of excised organs was performed. Intracellular cytoplasmatic uptake of gadophrin-2 was confirmed by electron microscopy. Spectrometry determined an uptake of 31.56 nmol Gd per 10 6 cells. After intravenous injection, the distribution of gadophrin-2 labeled cells in nude mice could be visualized by MR, OI, and fluorescence microscopy. At 4 h p.i., the transplanted cells mainly distributed to lung, liver, and spleen, and 24 h p.i. they also distributed to the bone marrow. Fluorescence microscopy confirmed the distribution of gadophrin-2 labeled cells to these target organs. Gadophrin-2 is suited as a bifunctional contrast agent for MR imaging, OI, and fluorescence microscopy and may be used to combine the advantages of each individual imaging modality for in vivo tracking of intravenously injected hematopoietic cells. (orig.)

Novel Synthetic Monothiourea Aspirin Derivatives Bearing Alkylated Amines as Potential Antimicrobial Agents

Directory of Open Access Journals (Sweden)

Norsyafikah Asyilla Nordin

2017-01-01

Full Text Available A new series of aspirin bearing alkylated amines moieties 1–12 were synthesised by reacting isothiocyanate with a series of aniline derivatives in overall yield of 16–56%. The proposed structures of all the synthesised compounds were confirmed using elemental analysis, FTIR, and 1H and  13C NMR spectroscopy. All compounds were evaluated for antibacterial activities against E. coli and S. aureus via turbidimetric kinetic and Kirby Bauer disc diffusion method. Compound 5 bearing meta -CH3 substituent showed the highest relative inhibition zone diameter against tested bacteria compared to ortho and para substituent. Furthermore, aspirin derivatives bearing shorter chains exhibited better bacterial inhibition than longer alkyl chains.

Optimizing the use of alkylators in neuro-oncology

OpenAIRE

Perry, J R; Wick, W; Weller, M

2011-01-01

For more than three decades, alkylating agents have been the most widely used class of chemotherapeutic agents for the treatment of glial brain tumors. Today, concomitant and adjuvant temozolomide is the standard of care for newly diagnosed glioblastoma. Temozolomide alone or in combination with radiotherapy is being explored in ongoing trials in newly diagnosed patients with low-grade and anaplastic glioma. Rechallenge with alternative dosing schedules of temozolomide is a valid treatment op...

Alkylating agent methyl methanesulfonate (MMS) induces a wave of global protein hyperacetylation: Implications in cancer cell death

International Nuclear Information System (INIS)

Lee, Min-Young; Kim, Myoung-Ae; Kim, Hyun-Ju; Bae, Yoe-Sik; Park, Joo-In; Kwak, Jong-Young; Chung, Jay H.; Yun, Jeanho

2007-01-01

Protein acetylation modification has been implicated in many cellular processes but the direct evidence for the involvement of protein acetylation in signal transduction is very limited. In the present study, we found that an alkylating agent methyl methanesulfonate (MMS) induces a robust and reversible hyperacetylation of both cytoplasmic and nuclear proteins during the early phase of the cellular response to MMS. Notably, the acetylation level upon MMS treatment was strongly correlated with the susceptibility of cancer cells, and the enhancement of MMS-induced acetylation by histone deacetylase (HDAC) inhibitors was shown to increase the cellular susceptibility. These results suggest protein acetylation is important for the cell death signal transduction pathway and indicate that the use of HDAC inhibitors for the treatment of cancer is relevant

Aag-initiated base excision repair drives alkylation-induced retinal degeneration in mice.

Science.gov (United States)

Meira, Lisiane B; Moroski-Erkul, Catherine A; Green, Stephanie L; Calvo, Jennifer A; Bronson, Roderick T; Shah, Dharini; Samson, Leona D

2009-01-20

Vision loss affects >3 million Americans and many more people worldwide. Although predisposing genes have been identified their link to known environmental factors is unclear. In wild-type animals DNA alkylating agents induce photoreceptor apoptosis and severe retinal degeneration. Alkylation-induced retinal degeneration is totally suppressed in the absence of the DNA repair protein alkyladenine DNA glycosylase (Aag) in both differentiating and postmitotic retinas. Moreover, transgenic expression of Aag activity restores the alkylation sensitivity of photoreceptors in Aag null animals. Aag heterozygotes display an intermediate level of retinal degeneration, demonstrating haploinsufficiency and underscoring that Aag expression confers a dominant retinal degeneration phenotype.

Metal halide-phosphorus halide-alkyl halide complexes: reaction with niobium and tantalum pentachlorides

International Nuclear Information System (INIS)

Puri, D.M.; Saini, M.S.

1978-01-01

The reactions of niobium and tantalum pentachlorides with trichlorophosphine and phenyldichlorophosphine have been studied in presence of alkylating agents such as sec-butyl chloride, iso-butyl chloride, tert-butyl chloride, tert-anylchloride, cyclohexyl chloride and triphenylmethyl chloride. Solid products have been isolated and characterised by vibrational spectroscopy as ionic complexes of alkyl- and/or aryl-phosphonium cations with hexachloroniobate and hexachlorotantalate anions. (author)

Parp1 protects against Aag-dependent alkylation-induced nephrotoxicity in a sex-dependent manner.

Science.gov (United States)

Calvo, Jennifer A; Allocca, Mariacarmela; Fake, Kimberly R; Muthupalani, Sureshkumar; Corrigan, Joshua J; Bronson, Roderick T; Samson, Leona D

2016-07-19

Nephrotoxicity is a common toxic side-effect of chemotherapeutic alkylating agents. Although the base excision repair (BER) pathway is essential in repairing DNA alkylation damage, under certain conditions the initiation of BER produces toxic repair intermediates that damage healthy tissues. We have shown that the alkyladenine DNA glycosylase, Aag (a.k.a. Mpg), an enzyme that initiates BER, mediates alkylation-induced whole-animal lethality and cytotoxicity in the pancreas, spleen, retina, and cerebellum, but not in the kidney. Cytotoxicity in both wild-type and Aag-transgenic mice (AagTg) was abrogated in the absence of Poly(ADP-ribose) polymerase-1 (Parp1). Here we report that Parp1-deficient mice expressing increased Aag (AagTg/Parp1-/-) develop sex-dependent kidney failure upon exposure to the alkylating agent, methyl methanesulfonate (MMS), and suffer increased whole-animal lethality compared to AagTg and wild-type mice. Macroscopic, histological, electron microscopic and immunohistochemical analyses revealed morphological kidney damage including dilated tubules, proteinaceous casts, vacuolation, collapse of the glomerular tuft, and deterioration of podocyte structure. Moreover, mice exhibited clinical signs of kidney disease indicating functional damage, including elevated blood nitrogen urea and creatinine, hypoproteinemia and proteinuria. Pharmacological Parp inhibition in AagTg mice also resulted in sensitivity to MMS-induced nephrotoxicity. These findings provide in vivo evidence that Parp1 modulates Aag-dependent MMS-induced nephrotoxicity in a sex-dependent manner and highlight the critical roles that Aag-initiated BER and Parp1 may play in determining the side-effects of chemotherapeutic alkylating agents.

Synthesis of 11C-labelled haloalkanonitriles and examples of their use in some alkylation reactions

International Nuclear Information System (INIS)

Hoernfeldt, K.; Antoni, G.; Laangstroem, B.

1992-01-01

The synthesis of the 11 C-labelled bifunctional precursors 4-iodobutyro[ 11 C]nitrile (1), 4-tosyloxybutyro[ 11 C]nitrile (2), 5-iodovalero[ 11 C]nitrile (3), 5-toxyloxyvalero[ 11 C]nitrile (4) and 4-bromopentano[ 11 C]nitrile (5) are presented. The nucleophilic substitution reactions of [ 11 C]cyanide with dibromides, diiodides, ditosylates or mixed iodotosylates producing 1-5 have been carried out in different solvents and the labelled products were obtained in 62-98% radiochemical yields (not isolated), with a total synthesis time of 5 min counted from the end of the hydrogen [ 11 C]cyanide synthesis. The labelled haloalkanonitriles 1 and 3 have also been used in some alkylation reactions with various carbon and oxygen nucleophiles. (au)

In vitro susceptibilities in lymphocytes from mothers and cord blood to the monofunctional alkylating agent EMS

DEFF Research Database (Denmark)

Wyatt, N P; Falque-Gonzalez, C; Farrar, D

2007-01-01

at the Bradford Royal Infirmary collected venous blood samples from mothers at the time of birth and venous cord blood post-delivery. Lymphocytes were isolated from both blood types and examined in the alkaline comet assay using the monofunctional alkylating agent ethyl methanesulphonate (EMS). There were...... no biologically significant differences when subjects were categorized into subgroups based on lifestyle habits and physical characteristics, and overall there were no statistically significant differences in levels of DNA damage in mothers (n=22) and babies (n=22), except at the basal level (P... values in babies were always lower over the EMS dose range. Whole blood was used in the micronucleus (MN) assay, and there was a significantly (Prate of MN in mothers (n=17), per 1000 binucleates, as compared with lymphocytes from their offspring (n=17) at the basal level. This may...

Single flexible nanofiber to simultaneously realize electricity-magnetism bifunctionality

International Nuclear Information System (INIS)

Yang, Ming; Sheng, Shujuan; Ma, Qianli; Lv, Nan; Yu, Wensheng; Wang, Jinxian; Dong, Xiangting; Liu, Guixia

2016-01-01

In order to develop new-typed multifunctional composite nanofibers, PANI/Fe 3 O 4 /PVP flexible bifunctional composite nanofibers with simultaneous electrical conduction and magnetism have been successfully fabricated via a facile electrospinning technology. Polyvinyl pyrrolidone (PVP) is used as a matrix to construct composite nanofibers containing different amounts of polyaniline (PANI) and Fe 3 O 4 nanoparticles (NPs). The bifunctional composite nanofibers simultaneously possess excellent electrical conductivity and magnetic properties. The electrical conductivity reaches up to the order of 10 -3 S·cm -1 . The electrical conductivity and saturation magnetization of the composite nanofibers can be respectively tuned by adding various amounts of PANI and Fe 3 O 4 NPs. The obtained electricity-magnetism bifunctional composite nanofibers are expected to possess many potential applications in areas such as electromagnetic interference shielding, special coating, microwave absorption, molecular electronics and future nanomechanics. More importantly, the design concept and construct technique are of universal significance to fabricate other bifunctional one-dimensional nanostructures. (author)

Carbon in bifunctional air electrodes in alkaline solution

International Nuclear Information System (INIS)

Tryk, D.; Aldred, W.; Yeager, E.

1983-01-01

Bifunctional O 2 electrodes can be used both to reduce and to generate O 2 in rechargeable metal-air batteries and fuel cells. The factors controlling the O 2 reduction and generation reactions in gas-diffusional bifunctional O 2 electrodes are discussed. The resistance of such electrodes, as established from voltammetry curves, has been found to increase markedly during anodic polarization and to be dependent upon the electrode fabrication technique. Carbon blacks with more graphitic structure than Shawinigan black have been found to be more resistant to electro-oxidation. The further extension of cycle life of bifunctional electrodes using carbon is critically dependent on finding more oxidation-resistant carbons that at the same time have other surface properties meeting the requirements for catalyzed gas-diffusion electrodes

Solvent extraction of uranium(VI), plutonium(VI) and americium(III) with HTTA/HPMBP using mono- and bi-functional neutral donors. Synergism and thermodynamics

International Nuclear Information System (INIS)

Pai, S.A.; Lohithakshan, K.V.; Mithapara, P.D.; Aggarwal, S.K.

2000-01-01

Synergistic extraction of hexavalent uranium and plutonium as well as trivalent americium was studied in HNO 3 with thenoyl, trifluoro-acetone (HTTA)/1-phenyl, 3-methyl, 4-benzoyl pyrazolone-5 (HPMBP) in combination with neutral donors viz. DPSO, TBP, TOPO (mono-functional) and DBDECMP, DHDECMP, CMPO (bi-functional) with wide basicity range using benzene as diluent. A linear correlation was observed when the equilibrium constant log Ks for the organic phase synergistic reaction of both U(VI) and Pu(VI) with either of the chelating agents HTTA or HPMBP was plotted vs. the basicity (log Kh) of the donor (both mono- and bi-functional) indicating bi-functional donors also behave as mono-functional. This was supported by the thermodynamic data (ΔG 0 , ΔH 0 , ΔS 0 ) obtained for these systems. The organic phase adduct formation reactions were identified for the above systems from the thermodynamic data. In the Am(III) HTTA system log K s values of bi-functional donors were found to be very high and deviate from the linear plot (log K s vs. log K h ) obtained for mono-functional donors, indicating that they function as bi-functional for the Am(III)/HTTA) system studied. This was supported by high +ve ΔS 0 values obtained for this system. (author)

Effects of alkylating carcinogens on human tumor cells in culture

International Nuclear Information System (INIS)

Goth-Goldstein, R.; Hughes, M.

1987-01-01

In Escherichia coli 3-methyladenine and 3-methylguanine have been identified as lethal lesions, since two types of alkylating agent-sensitive mutants were deficient in repair of either of these lesions. Similar alkylation-sensitive human cell lines exist. These are the tumor cell lines of the complex Mer - phenotype. All Mer - cells examined were hypersensitive to killing by MNNG and other alkylating agents, and failed to repair O 6 -methylguanine. The widely studied HeLa S3 cell line has the Mer + phenotype, but a Mer - variant (HeLa MR) has arisen. This offers the possibility to study Mer - and Mer + cells of otherwise similar genetic background. We are using these two variants to analyze the Mer - phenotype further. When HeLa S3 and HeLa MR were treated with a highly dose of MNNG, and the surviving population exposed to a second dose of MNNG 2-3 weeks later, HeLa S3 (Mer + ) cells were equally or even slightly more sensitive to a second exposure of MNNG, whereas the surviving HeLa MR (Mer - ) population was much more resistant to MNNG. 1 fig., 1 tab

Quantum molecular modeling of the interaction between guanine and alkylating agents--1--sulfur mustard.

Science.gov (United States)

Broch, H; Hamza, A; Vasilescu, D

1996-06-01

Interaction between Guanine and the episulfonium form of Sulfur mustard (HD) was studied using the ab initio LCAO-MO method at the HF/6-31G level. The alkylation mechanism on guanine-N7 was analyzed by using a supermolecular modeling. Our stereostructural results associated with the molecular electrostatic potentials and HOMO-LUMO properties, show that in vacuum the alkylation of the N7 of guanine by HD in the aggressive episulfonium form is a direct process without transition state and of which the pathway is determined.

Chichibabin-type direct alkylation of pyridyl alcohols with alkyl lithium reagents.

Science.gov (United States)

Jeffrey, Jenna L; Sarpong, Richmond

2012-11-02

Direct C(6) alkylation of pyridyl alcohols can be achieved following an initial deprotonation of the hydroxy group. This transformation, which is believed to occur by a Chichibabin-type alkylation, avoids lateral deprotonation prior to pyridine ring alkylation and gives increased regioselectivity for C(6) over C(4) alkylation.

User-friendly aerobic reductive alkylation of iridium(III) porphyrin chloride with potassium hydroxide: scope and mechanism.

Science.gov (United States)

Zuo, Huiping; Liu, Zhipeng; Yang, Wu; Zhou, Zhikuan; Chan, Kin Shing

2015-12-21

Alkylation of iridium 5,10,15,20-tetrakistolylporphyrinato carbonyl chloride, Ir(ttp)Cl(CO) (1), with 1°, 2° alkyl halides was achieved to give (ttp)Ir-alkyls in good yields under air and water compatible conditions by utilizing KOH as the cheap reducing agent. The reaction rate followed the order: RCl < RBr < RI (R = alkyl), and suggests an SN2 pathway by [Ir(I)(ttp)](-). Ir(ttp)-adamantyl was obtained under N2 when 1-bromoadamantane was utilized, which could only undergo bromine atom transfer pathway. Mechanistic investigations reveal a substrate dependent pathway of SN2 or halogen atom transfer.

An in-situ FTIR study of the side-chain alkylation of toluene with methanol

International Nuclear Information System (INIS)

King, S.T.; Garces, J.

1985-01-01

The side-chain alkylation of toluene with methanol to styrene and ethylbenzene can be an economically attractive industrial process if it has high enough conversion and selectivity. This process has been investigated by many others using zeolites or metal oxides as the catalyst. It has been generally accepted that high basicity in certain size pores in the catalyst is required for such side-chain alkylation. However, the actual reaction mechanism is still not understood. In this paper the results of an in-situ FT-IR study of the side-chain alkylation in Li, Na, K, Rb and Cs exchanged X zeolites is discussed. It was found that the KX, RbX and CsX zeolites, which are capable of side-chain alkylation, also form surface formate and a surface precursor of formate from methanol decomposition. While the surface formate itself is not the alkylation agent, the observed formate precursor may be the intermediate for side-chain alkylation

Thioredoxin Cross-Linking by Nitrogen Mustard in Lung Epithelial Cells: Formation of Multimeric Thioredoxin/Thioredoxin Reductase Complexes and Inhibition of Disulfide Reduction

OpenAIRE

Jan, Yi-Hua; Heck, Diane E.; Casillas, Robert P.; Laskin, Debra L.; Laskin, Jeffrey D.

2015-01-01

The thioredoxin (Trx) system, which consists of Trx and thioredoxin reductase (TrxR), is a major cellular disulfide reduction system important in antioxidant defense. TrxR is a target of mechlorethamine (methylbis(2-chloroethyl)amine; HN2), a bifunctional alkylating agent that covalently binds to selenocysteine/cysteine residues in the redox centers of the enzyme, leading to inactivation and toxicity. Mammalian Trx contains two catalytic cysteines; herein, we determined if HN2 also targets Tr...

Single flexible nanofiber to simultaneously realize electricity-magnetism bifunctionality

Energy Technology Data Exchange (ETDEWEB)

Yang, Ming; Sheng, Shujuan; Ma, Qianli; Lv, Nan; Yu, Wensheng; Wang, Jinxian; Dong, Xiangting; Liu, Guixia, E-mail: wenshengyu2009@sina.com, E-mail: dongxiangting888@163.com [Key Laboratory of Applied Chemistry and Nanotechnology at Universities of Jilin Province, Changchun University of Science and Technology, Changchun (China)

2016-03-15

In order to develop new-typed multifunctional composite nanofibers, PANI/Fe{sub 3}O{sub 4}/PVP flexible bifunctional composite nanofibers with simultaneous electrical conduction and magnetism have been successfully fabricated via a facile electrospinning technology. Polyvinyl pyrrolidone (PVP) is used as a matrix to construct composite nanofibers containing different amounts of polyaniline (PANI) and Fe{sub 3}O{sub 4} nanoparticles (NPs). The bifunctional composite nanofibers simultaneously possess excellent electrical conductivity and magnetic properties. The electrical conductivity reaches up to the order of 10{sup -3} S·cm{sup -1}. The electrical conductivity and saturation magnetization of the composite nanofibers can be respectively tuned by adding various amounts of PANI and Fe{sub 3}O{sub 4} NPs. The obtained electricity-magnetism bifunctional composite nanofibers are expected to possess many potential applications in areas such as electromagnetic interference shielding, special coating, microwave absorption, molecular electronics and future nanomechanics. More importantly, the design concept and construct technique are of universal significance to fabricate other bifunctional one-dimensional nanostructures. (author)

Transcriptional blockages in a cell-free system by sequence-selective DNA alkylating agents.

Science.gov (United States)

Ferguson, L R; Liu, A P; Denny, W A; Cullinane, C; Talarico, T; Phillips, D R

2000-04-14

There is considerable interest in DNA sequence-selective DNA-binding drugs as potential inhibitors of gene expression. Five compounds with distinctly different base pair specificities were compared in their effects on the formation and elongation of the transcription complex from the lac UV5 promoter in a cell-free system. All were tested at drug levels which killed 90% of cells in a clonogenic survival assay. Cisplatin, a selective alkylator at purine residues, inhibited transcription, decreasing the full-length transcript, and causing blockage at a number of GG or AG sequences, making it probable that intrastrand crosslinks are the blocking lesions. A cyclopropylindoline known to be an A-specific alkylator also inhibited transcription, with blocks at adenines. The aniline mustard chlorambucil, that targets primarily G but also A sequences, was also effective in blocking the formation of full-length transcripts. It produced transcription blocks either at, or one base prior to, AA or GG sequences, suggesting that intrastrand crosslinks could again be involved. The non-alkylating DNA minor groove binder Hoechst 33342 (a bisbenzimidazole) blocked formation of the full-length transcript, but without creating specific blockage sites. A bisbenzimidazole-linked aniline mustard analogue was a more effective transcription inhibitor than either chlorambucil or Hoechst 33342, with different blockage sites occurring immediately as compared with 2 h after incubation. The blockages were either immediately prior to AA or GG residues, or four to five base pairs prior to such sites, a pattern not predicted from in vitro DNA-binding studies. Minor groove DNA-binding ligands are of particular interest as inhibitors of gene expression, since they have the potential ability to bind selectively to long sequences of DNA. The results suggest that the bisbenzimidazole-linked mustard does cause alkylation and transcription blockage at novel DNA sites. in addition to sites characteristic of

Crystallization of bi-functional ligand protein complexes.

Science.gov (United States)

Antoni, Claudia; Vera, Laura; Devel, Laurent; Catalani, Maria Pia; Czarny, Bertrand; Cassar-Lajeunesse, Evelyn; Nuti, Elisa; Rossello, Armando; Dive, Vincent; Stura, Enrico Adriano

2013-06-01

Homodimerization is important in signal transduction and can play a crucial role in many other biological systems. To obtaining structural information for the design of molecules able to control the signalization pathways, the proteins involved will have to be crystallized in complex with ligands that induce dimerization. Bi-functional drugs have been generated by linking two ligands together chemically and the relative crystallizability of complexes with mono-functional and bi-functional ligands has been evaluated. There are problems associated with crystallization with such ligands, but overall, the advantages appear to be greater than the drawbacks. The study involves two matrix metalloproteinases, MMP-12 and MMP-9. Using flexible and rigid linkers we show that it is possible to control the crystal packing and that by changing the ligand-enzyme stoichiometric ratio, one can toggle between having one bi-functional ligand binding to two enzymes and having the same ligand bound to each enzyme. The nature of linker and its point of attachment on the ligand can be varied to aid crystallization, and such variations can also provide valuable structural information about the interactions made by the linker with the protein. We report here the crystallization and structure determination of seven ligand-dimerized complexes. These results suggest that the use of bi-functional drugs can be extended beyond the realm of protein dimerization to include all drug design projects. Copyright © 2013 Elsevier Inc. All rights reserved.

The role of the HCR system in the repair of lethal lesions of Bacillus subtilis phages and their transfecting DNA damaged by radiation and alkylating agents

International Nuclear Information System (INIS)

Vizdalova, M.; Janovska, E.; Zhestyanikov, V.D.

1980-01-01

The role of the HCR system in the repair of prelethal lesions induced by UV light, γ radiation and alkylating agents was studied in the Bacillus subtilis SPP1 phage, its heat sensitive mutants (N3, N73 nad ts 1 ) and corresponding infectious DNA. The survival of phages and their transfecting DNA after treatment with UV light is substantially higher in hcr + cells than in hcr cells, the differences being more striking in intact phages than in their transfecting DNA's. Repair inhibitors reduce survival in hcr + cells: caffeine lowers the survival of UV-irradiated phage SPP1 in exponentially growing hcr + cells but has no effect on its survival in competent hcr + cells; acriflavin and ethidium bromide decrease the survival of the UV-irradiated SPP1 phage in both exponentially growing and competent hcr + cells to the level of survival observed in hcr cells; moreover, ethidium bromide lowers the number of infective centres in hcr + cells of the UV-irradiated DNA of the SPP1 phage. Repair inhibitors do not lower the survival of the UV-irradiated phages or their DNA in hcr cells. The repair mechanism under study also effectively repairs lesions induced by polyfunctional alkylating agents in the transfecting DNA's of B. subtilis phages but is not functional with lesions induced by these agents in free phages and lesions caused in the phages and their DNA by ethyl methanesulphonate or γ radiation. (author)

Alkylation sensitivity screens reveal a conserved cross-species functionome

Science.gov (United States)

Svilar, David; Dyavaiah, Madhu; Brown, Ashley R.; Tang, Jiang-bo; Li, Jianfeng; McDonald, Peter R.; Shun, Tong Ying; Braganza, Andrea; Wang, Xiao-hong; Maniar, Salony; St Croix, Claudette M.; Lazo, John S.; Pollack, Ian F.; Begley, Thomas J.; Sobol, Robert W.

2013-01-01

To identify genes that contribute to chemotherapy resistance in glioblastoma, we conducted a synthetic lethal screen in a chemotherapy-resistant glioblastoma derived cell line with the clinical alkylator temozolomide (TMZ) and an siRNA library tailored towards “druggable” targets. Select DNA repair genes in the screen were validated independently, confirming the DNA glycosylases UNG and MYH as well as MPG to be involved in the response to high dose TMZ. The involvement of UNG and MYH is likely the result of a TMZ-induced burst of reactive oxygen species. We then compared the human TMZ sensitizing genes identified in our screen with those previously identified from alkylator screens conducted in E. coli and S. cerevisiae. The conserved biological processes across all three species composes an Alkylation Functionome that includes many novel proteins not previously thought to impact alkylator resistance. This high-throughput screen, validation and cross-species analysis was then followed by a mechanistic analysis of two essential nodes: base excision repair (BER) DNA glycosylases (UNG, human and mag1, S. cerevisiae) and protein modification systems, including UBE3B and ICMT in human cells or pby1, lip22, stp22 and aim22 in S. cerevisiae. The conserved processes of BER and protein modification were dual targeted and yielded additive sensitization to alkylators in S. cerevisiae. In contrast, dual targeting of BER and protein modification genes in human cells did not increase sensitivity, suggesting an epistatic relationship. Importantly, these studies provide potential new targets to overcome alkylating agent resistance. PMID:23038810

Radioiodination of proteins by reductive alkylation

International Nuclear Information System (INIS)

Panuska, J.R.; Parker, C.W.

1987-01-01

The use of the aliphatic aldehyde, para-hydroxyphenylacetaldehyde as the reactive moiety in the radioiodination of proteins by reductive alkylation is described. The para-hydroxyphenyl group is radiolabeled with 125 I, reacted through its aliphatic aldehyde group with primary amino groups on proteins to form a reversible Schiff base linkage which can then be stabilized with the mild reducing agent NaCNBH 3 . The introduction of the methylene group between the benzene ring and the aldehyde group increases its reactivity with protein amino groups permitting efficient labeling at low aldehyde concentrations. Using this method, radioiodinated proteins with high specific activity can be produced. The reductive alkylation procedure is advantageous in that the labeling conditions are mild, the reaction is specific for lysyl residues, and the modification of the epsilon-ammonium group of lysine results in ionizable secondary amino groups avoiding major changes in protein charge

Role of O6-alkylguanine-DNA alkyltransferase in the resistance of mouse spermatogenic cells to O6-alkylating agents.

Science.gov (United States)

Thompson, M J; Abdul-Rahman, S; Baker, T G; Rafferty, J A; Margison, G P; Bibby, M C

2000-07-01

The O(6)-alkylguanine-DNA alkyltransferase inactivator O(6)-benzylguanine was administered to BALB/c mice either alone or before exposure to 1,3-bis(2-chloroethyl)-1-nitrosourea to study the role of the DNA repair protein O(6)-alkylguanine-DNA alkyltransferase in the protection of the testis against anti-cancer O(6)-alkylating agents. Exposure of the mice to 1, 3-bis(2-chloroethyl)-1-nitrosourea or O(6)-benzylguanine alone did not produce any marked testicular toxicity at the times studied. Testicular O(6)-alkylguanine-DNA alkyltransferase concentrations were assayed between 0 and 240 min after O(6)-benzylguanine treatment and were shown to be > 95% depleted 15 min after treatment with O(6)-benzylguanine and remained at > 95% at all the times assayed. Histological examination, the reduction in testicular mass and the induction of spermatogenic cell apoptosis showed that this depletion significantly potentiated 1, 3-bis(2-chloroethyl)-1-nitrosourea-induced testicular damage after treatment. Major histological damage was apparent 42 days after treatment, demonstrating that the stem spermatogonia were significantly affected by the combination. These results demonstrate that O(6)-alkylguanine-DNA alkyltransferase plays a significant role in protecting the spermatogenic cells from damage caused by DNA alkylation and indicate that the observed toxicity may result from damage to stem spermatogonia.

Single flexible nanofiber to achieve simultaneous photoluminescence-electrical conductivity bifunctionality.

Science.gov (United States)

Sheng, Shujuan; Ma, Qianli; Dong, Xiangting; Lv, Nan; Wang, Jinxian; Yu, Wensheng; Liu, Guixia

2015-02-01

In order to develop new-type multifunctional composite nanofibers, Eu(BA)3 phen/PANI/PVP bifunctional composite nanofibers with simultaneous photoluminescence and electrical conductivity have been successfully fabricated via electrospinning technology. Polyvinyl pyrrolidone (PVP) is used as a matrix to construct composite nanofibers containing different amounts of Eu(BA)3 phen and polyaniline (PANI). X-Ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), fluorescence spectroscopy and a Hall effect measurement system are used to characterize the morphology and properties of the composite nanofibers. The results indicate that the bifunctional composite nanofibers simultaneously possess excellent photoluminescence and electrical conductivity. Fluorescence emission peaks of Eu(3+) ions are observed in the Eu(BA)3 phen/PANI/PVP photoluminescence-electrical conductivity bifunctional composite nanofibers. The electrical conductivity reaches up to the order of 10(-3)  S/cm. The luminescent intensity and electrical conductivity of the composite nanofibers can be tuned by adjusting the amounts of Eu(BA)3 phen and PANI. The obtained photoluminescence-electrical conductivity bifunctional composite nanofibers are expected to possess many potential applications in areas such as microwave absorption, molecular electronics, biomedicine and future nanomechanics. More importantly, the design concept and construction technique are of universal significance to fabricate other bifunctional one-dimensional naonomaterials. Copyright © 2014 John Wiley & Sons, Ltd.

Improving the spectrophotometric determination of the alkylating activity of anticancer agents: a new insight into the mechanism of the NBP method.

Science.gov (United States)

Dierickx, Karen M E; Journé, Fabrice; Gerbaux, Pascal; Morandini, Renato; Kauffmann, Jean-Michel; Ghanem, Ghanem E

2009-02-15

In this paper, the mechanism of the nitrobenzylpyridine (NBP) method to measure the alkylating activity of drugs originally described by Epstein et al. [J. Epstein, R.W. Rosenthal, R.J. Ess, Anal. Chem. 27 (1955) 1435-1439] and modified later by others was revisited using melphalan, m-sarcolysin, chlorambucil, cyclophosphamide and ifosfamide. Its direct application to determine the activity of these drugs in human serum and aqueous media is described and discussed. This method, based on the formation of a chromophore due to the reaction between the alkylating agent and NBP, was significantly improved by extracting as quickly as possible the reaction product(s) into chloroform before adding alkali to develop the color. This significantly limited the degradation by hydrolysis of the products and enhanced the yield of the end chromophore in the organic phase. The reaction time was optimized by monitoring each compound color development. The best reaction time for each compound was selected and a higher stability of the extracted color over at least 1h was obtained (compared to a couple of minutes in previous studies). Most interestingly, water evaporation due to heating had little or no effect on the linearity of standard curves evaluated in the micromolar concentration range. Both the sensitivity and reproducibility of the method were therefore significantly improved. There appears to be a direct correlation between compound hydrolysis and alkylation activity; the relative reactivity is different among the compounds owing to the rate of (i) production, (ii) the relative proportions and (iii) the hydrolysis of the intermediates. A general mechanism for the nucleophilic competitive substitution is proposed.

In vitro study of cytotoxicity by U.V. radiation and differential sensitivity in combination with alkylating agents on established cell systems

International Nuclear Information System (INIS)

Ramudu, K.

1991-01-01

The effect of U.V. radiation or alkylating agents, such as actinomycin-D, cycloheximide and mitomycin-C (MMC), was studied on CHO, BHK and HeLa cells. U.V. radiation caused DNA ssb and dsb and were prevented by cycloheximide and actinomycin-D. MMC is known to be cytotoxic in CHO/BHK cells by forming free radical generation. MMC in combination with U.V. radiation enhanced DNA ssb ampersand dsb in these cell types. However, HeLa cells were insensitive to U.V. radiation. This insensitivity to U.V. radiation could be ascribed to the presence of glutathione transferase which is absent in CHO/BHK cell line

Digital PCR assessment of MGMT promoter methylation coupled with reduced protein expression optimises prediction of response to alkylating agents in metastatic colorectal cancer patients.

Science.gov (United States)

Sartore-Bianchi, Andrea; Pietrantonio, Filippo; Amatu, Alessio; Milione, Massimo; Cassingena, Andrea; Ghezzi, Silvia; Caporale, Marta; Berenato, Rosa; Falcomatà, Chiara; Pellegrinelli, Alessio; Bardelli, Alberto; Nichelatti, Michele; Tosi, Federica; De Braud, Filippo; Di Nicolantonio, Federica; Barault, Ludovic; Siena, Salvatore

2017-01-01

O(6)-methylguanine-DNA-methyltransferase (MGMT) is a repair protein, and its deficiency makes tumours more susceptible to the cytotoxic effect of alkylating agents. Five clinical trials with temozolomide or dacarbazine have been performed in metastatic colorectal cancer (mCRC) with selection based on methyl-specific PCR (MSP) testing with modest results. We hypothesised that mitigated results are consequences of unspecific patient selection and that alternative methodologies for MGMT testing such as immunohistochemistry (IHC) and digital polymerase chain reaction (PCR) could enhance patient enrolment. Formalin-fixed paraffin embedded archival tumour tissue samples from four phase II studies of temozolomide or dacarbazine in MGMT MSP-positive mCRCs were analysed by IHC for MGMT protein expression and by methyl-BEAMing (MB) for percentage of promoter methylation. Pooled data were then retrospectively analysed according to objective response rate, progression-free survival (PFS) and overall survival (OS). One hundred and five patients were included in the study. Twelve had achieved partial response (PR) (11.4%), 24 stable disease (SD; 22.9%) and 69 progressive disease (PD; 65.7%). Patients with PR/SD had lower IHC scores and higher MB levels than those with PD. MGMT expression by IHC was negatively and MB levels positively associated with PFS (p alkylating agents. Their combination could enhance patient selection in this setting. Copyright © 2016 Elsevier Ltd. All rights reserved.

Acquisition of resistance to antitumor alkylating agent ACNU: a possible target of positron emission tomography monitoring

Energy Technology Data Exchange (ETDEWEB)

Kawai, Hideya [Department of Neurosurgery, Faculty of Medical Sciences, University of Fukui, Fukui 910-1193 (Japan); Research Institute of Brain and Blood Vessels, Akita 010-0874 (Japan); Toyohara, Jun [Radiopharmaceutical Chemistry Section, Department of Medical Imaging, National Institute of Radiological Sciences, Chiba 263-8555 (Japan); Biomedical Imaging Research Center, University of Fukui, Fukui 910-1193 (Japan); Kado, Hirotsugu [Research Institute of Brain and Blood Vessels, Akita 010-0874 (Japan); Nakagawa, Takao [Department of Neurosurgery, Faculty of Medical Sciences, University of Fukui, Fukui 910-1193 (Japan); Takamatsu, Shinji [Biomedical Imaging Research Center, University of Fukui, Fukui 910-1193 (Japan); Furukawa, Takako [Biomedical Imaging Research Center, University of Fukui, Fukui 910-1193 (Japan); Yonekura, Yoshiharu [Biomedical Imaging Research Center, University of Fukui, Fukui 910-1193 (Japan); Kubota, Toshihiko [Department of Neurosurgery, Faculty of Medical Sciences, University of Fukui, Fukui 910-1193 (Japan); Fujibayashi, Yasuhisa [Biomedical Imaging Research Center, University of Fukui, Fukui 910-1193 (Japan)]. E-mail: yfuji@fmsrsa.fukui-med.ac.jp

2006-01-15

Early detection of tumor response to chemotherapy is of great importance for appropriate treatment of tumors. In this study, characteristics of two positron emission tomography (PET) tracers, [{sup 18}F]2-fluoro-2-deoxy-D-glucose (FDG) and[{sup 18}F]3'-fluoro-3'-deoxy-thymidine (FLT), in the early detection of tumor cell response as well as tolerance development to chemotherapy was compared using rat C6 glioma cells and 1-(4-amino-2-methyl-5-pyrimidinyl)-methyl-3-(2-chloroethyl) -3-nitrosoureahydrochloride (ACNU). ACNU is an alkylating agent known to induce drug resistance through expression of O {sup 6}-methylguanine-deoxyribonucleic acid methyl transferase (O {sup 6}-MGMT). We established an ACNU-resistant C6 glioma cell line (C6/ACNU) and investigated the effect of ACNU on the uptake of FLT and FDG. In C6 cells, DNA synthesis presented as [{sup 3}H]thymidine ([{sup 3}H]Thd) incorporation into DNA was quickly suppressed by ACNU. In C6/ACNU cells, the suppression was recovered promptly, indicating that DNA alkylation occurs initially but highly expressed O {sup 6}-MGMT repairs DNA, leading to the recovery of DNA synthesis. The patterns of FLT uptake in C6 and C6/ACNU were difficult to distinguish in the very early stage of the treatment, though it was reported that FLT uptake well correlated with proliferation in certain conditions. FDG uptake showed different patterns between the resistant and control cells, with significantly decreased uptake in C6 cells and unchanged uptake in C6/ACNU cells at 18-24 h after the treatment. Though difficult to be directly translated into clinical situation, the present study will provide a base to develop an appropriate protocol to assess tumor response to treatment by PET and to design effective treatment plans.

Extended exposure to alkylator chemotherapy: delayed appearance of myelodysplasia.

Science.gov (United States)

Chamberlain, Marc C; Raizer, Jeffrey

2009-06-01

A case series of gliomas treated with alkylator-based chemotherapy who subsequently developed myelodysplastic syndrome (tMDS) or acute myelocytic leukemia (AML). Alkylator-based chemotherapy is recognized to be leukemogenic; however, it is infrequently described as a delayed consequence of anti-glioma treatment. Seven patients (4 men; 3 women) ages 34-69 years (median 44), with gliomas (3 Grade 2; 4 Grade 3) were treated with surgery, all but one with involved-field radiotherapy and all with alkylator-based chemotherapy (temozolomide; 6 patients, nitrosoureas; 5 patients, both agents; 5 patients). Exposure to alkylator-based chemotherapy ranged from 8 to 30 months (median 24). The diagnosis of tMDS was determined by bone marrow biopsy in 7 patients. Seven patients showed chromosomal abnormalities consistent with chemotherapy induced MDS. Three patients were diagnosed with AML as well (in two determined by bone marrow and one at autopsy). Interval from last chemotherapy exposure to diagnosis of tMDS/AML ranged from 3 to 31 months (median 24 months). Two patients were treated with bone marrow transplantation and 5 received supportive care only. Five patients have died, 2 as a consequence of recurrent brain tumor, 1 as a complication of transplantation, and 2 due to AML. Although rare, induction of tMDS/AML following extended use of alkylator-based chemotherapy may become more relevant with the evolving practice to treat gliomas for protracted periods. Future work to determine at risk patients would be important.

Distribution coefficients of purine alkaloids in water-ammonium sulfate-alkyl acetate-dialkyl phthalate systems

Science.gov (United States)

Korenman, Ya. I.; Krivosheeva, O. A.; Mokshina, N. Ya.

2012-12-01

The distribution of purine alkaloids (caffeine, theobromine, theophylline) was studied in the systems: alkyl acetates-dialkyl phtalate-salting-out agent (ammonium sulfate). The quantitative characteristics of the extraction-distribution coefficients ( D) and the degree of extraction ( R, %) are calculated. The relationships between the distribution coefficients of alkaloids and the length of the hydrocarbon radical in the molecule of alkyl acetate (dialkyl phtalate) are determined. The possibility of predicting the distribution coefficients is demonstrated.

Masked N-Heterocyclic Carbene-Catalyzed Alkylation of Phenols with Organic Carbonates.

Science.gov (United States)

Lui, Matthew Y; Yuen, Alexander K L; Masters, Anthony F; Maschmeyer, Thomas

2016-09-08

An easily prepared masked N-heterocyclic carbene, 1,3-dimethylimidazolium-2-carboxylate (DMI-CO2 ), was investigated as a "green" and inexpensive organocatalyst for the alkylation of phenols. The process made use of various low-toxicity and renewable alkylating agents, such as dimethyl- and diethyl carbonate, in a focused microwave reactor. DMI-CO2 was found to be a very active catalyst and excellent yields of a range of aryl alkyl ethers were obtained under relatively benign conditions. The observed difference in the conversion behavior of phenol methylation, in the presence of either the carbene or 1,8-diazabicycloundec-7-ene (DBU) catalyst, was rationalized on the basis of mechanistic investigations. The primary mode of action for the N-heterocyclic carbene is nucleophilic catalysis. Activation of the dialkyl carbonate electrophile results in concomitant evolution of an organo-soluble alkoxide, which deprotonates the phenolic starting material. In contrast, DBU is initially protonated by the phenol and thus consumed. Subsequent regeneration and participation in nucleophilic catalysis only becomes significant after some phenolate alkylation occurs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dose-Response for Multiple Biomarkers of Exposure and Genotoxic Effect Following Repeated Treatment of Rats with the Alkylating Agents, MMS and MNU.

Science.gov (United States)

Ji, Zhiying; LeBaron, Matthew J; Schisler, Melissa R; Zhang, Fagen; Bartels, Michael J; Gollapudi, B Bhaskar; Pottenger, Lynn H

2016-05-01

The nature of the dose-response relationship for various in vivo endpoints of exposure and effect were investigated using the alkylating agents, methyl methanesulfonate (MMS) and methylnitrosourea (MNU). Six male F344 rats/group were dosed orally with 0, 0.5, 1, 5, 25 or 50mg/kg bw/day (mkd) of MMS, or 0, 0.01, 0.1, 1, 5, 10, 25 or 50 mkd of MNU, for 4 consecutive days and sacrificed 24h after the last dose. The dose-responses for multiple biomarkers of exposure and genotoxic effect were investigated. In MMS-treated rats, the hemoglobin adduct level, a systemic exposure biomarker, increased linearly with dose (r (2) = 0.9990, P agents. © The Author 2015. Published by Oxford University Press on behalf of the UK Environmental Mutagen Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Synthesis and evaluation of novel bifunctional chelating agents based on 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid for radiolabeling proteins

International Nuclear Information System (INIS)

Chappell, L.L.; Ma, D.; Milenic, D.E.; Garmestani, K.; Venditto, V.; Beitzel, M.P.; Brechbiel, M.W.

2003-01-01

Detailed synthesis of the bifunctional chelating agents 2-methyl-6-(p-isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane-1,4,7,10 -tetraacetic acid (1B4M-DOTA) and 2-(p-isothiocyanatobenzyl)-5, 6-cyclohexano-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetate (CHX-DOTA) are reported. These chelating agents were compared to 2-(p-isothiocyanatobenzyl)-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid (C-DOTA) and 1, 4, 7, 10-Tetraaza-N-(1-carboxy-3-(4-nitrophenyl)propyl)-N', N'', N'''-tris(acetic acid) cyclododecane (PA-DOTA) as their 177 Lu radiolabeled conjugates with Herceptin TM . In vitro stability of the immunoconjugates radiolabeled with 177 Lu was assessed by serum stability studies. The in vivo stability of the radiolabeled immunoconjugates and their targeting characteristics were determined by biodistribution studies in LS-174T xenograft tumor-bearing mice. Relative radiolabeling rates and efficiencies were determined for all four immunoconjugates. Insertion of the 1B4M moiety into the DOTA backbone increases radiometal chelation rate and provides complex stability comparable to C-DOTA and PA-DOTA while the CHX-DOTA appears to not form as stable a 177 Lu complex while exhibiting a substantial increase in formation rate. The 1B4M-DOTAmay have potential for radioimmunotherapy applications. Published by Elsevier Inc. All rights reserved

On the influence of toxicity of O-alkyl serotonin derivatives on the implantation of their protective potency

International Nuclear Information System (INIS)

Vasin, M.V.; Suvorov, N.N.; Abramov, M.M.; Gordeev, E.N.

1987-01-01

In experiments with mongrel mice, a study was made of the pharmacological activity of serotonin and its O-alkyl derivatives. It was estimated by the two indices, that is, the radioprotective properties and the influence on a local blood cannel in the spleen, the modifying effect of the agents' toxicity being estimated as well. As an O-alkyl group of 5-alkoxytryptamines was elongated from one to three carbon atoms and the toxicity of the substances increased, their radiprotective effect decreased more readily than their effect on the local blood cannel. The shortening of the range of the therapeutic effect of the agents under study, with regard to the two pharmacological indices mentioned above, the alkyl group being lengthened, followed a logarithmic function which was more pronounced in relation to the radioprotective index (cosα 1 /cosα 2 =1.58)

Toward hypoxia-selective DNA-alkylating agents built by grafting nitrogen mustards onto the bioreductively activated, hypoxia-selective DNA-oxidizing agent 3-amino-1,2,4-benzotriazine 1,4-dioxide (tirapazamine).

Science.gov (United States)

Johnson, Kevin M; Parsons, Zachary D; Barnes, Charles L; Gates, Kent S

2014-08-15

Tirapazamine (3-amino-1,2,4-benzotriazine 1,4-dioxide) is a heterocyclic di-N-oxide that undergoes enzymatic deoxygenation selectively in the oxygen-poor (hypoxic) cells found in solid tumors to generate a mono-N-oxide metabolite. This work explored the idea that the electronic changes resulting from the metabolic deoxygenation of tirapazamine analogues might be exploited to activate a DNA-alkylating species selectively in hypoxic tissue. Toward this end, tirapazamine analogues bearing nitrogen mustard units were prepared. In the case of the tirapazamine analogue 18a bearing a nitrogen mustard unit at the 6-position, it was found that removal of the 4-oxide from the parent di-N-oxide to generate the mono-N-oxide analogue 17a did indeed cause a substantial increase in reactivity of the mustard unit, as measured by hydrolysis rates and DNA-alkylation yields. Hammett sigma values were measured to quantitatively assess the magnitude of the electronic changes induced by metabolic deoxygenation of the 3-amino-1,2,4-benzotriazine 1,4-dioxide heterocycle. The results provide evidence that the 1,2,4-benzotiazine 1,4-dioxide unit can serve as an oxygen-sensing prodrug platform for the selective unmasking of bioactive agents in hypoxic cells.

Bifunctional Interface of Au and Cu for Improved CO2 Electroreduction.

Science.gov (United States)

Back, Seoin; Kim, Jun-Hyuk; Kim, Yong-Tae; Jung, Yousung

2016-09-07

Gold is known currently as the most active single-element electrocatalyst for CO2 electroreduction reaction to CO. In this work, we combine Au with a second metal element, Cu, to reduce the amount of precious metal content by increasing the surface-to-mass ratio and to achieve comparable activity to Au-based catalysts. In particular, we demonstrate that the introduction of a Au-Cu bifunctional "interface" is more beneficial than a simple and conventional homogeneous alloying of Au and Cu in stabilizing the key intermediate species, *COOH. The main advantages of the proposed metal-metal bifunctional interfacial catalyst over the bimetallic alloys include that (1) utilization of active materials is improved, and (2) intrinsic properties of metals are less affected in bifunctional catalysts than in alloys, which can then facilitate a rational bifunctional design. These results demonstrate for the first time the importance of metal-metal interfaces and morphology, rather than the simple mixing of the two metals homogeneously, for enhanced catalytic synergies.

The relationship between reaction kinetics and mutagenic action of monofunctional alkylating agents in higher eukaryotic systems. IV. The effects of the excision-defective mei-9L1 and mus(2)201D1 mutants on alkylation-induced genetic damage in Drosophila.

Science.gov (United States)

Vogel, E W; Dusenbery, R L; Smith, P D

1985-04-01

Repair-defective mutants of Drosophila melanogaster which identify two major DNA excision repair loci have been examined for their effects on alkylation-induced mutagenesis using the sex-linked recessive lethal assay as a measure of genotoxic endpoint. The alkylating agents (AAs) chosen for comparative analysis were selected on the basis of their reaction kinetics with DNA and included MMS, EMS, MNU, DMN, ENU, DEN and ENNG. Repair-proficient males were treated with the AAs and mated with either excision-defective mei-9L1 or mus(2)201D1 females or appropriate excision-proficient control females. The results of the present work suggest that a qualitative and quantitative relationship exists between the nature and the extent of chemical modification of DNA and the induction of of genetic alterations. The presence of either excision-defective mutant can enhance the frequency of mutation (hypermutability) and this hypermutability can be correlated with the Swain-Scott constant S of specific AAs such that as the SN1 character of the DNA alkylation reaction increases, the difference in response between repair-deficient and repair-proficient females decreases. The order of hypermutability of AAs with mei-9L1 relative to mei-9+ is MMS greater than MNU greater than DMN = EMS greater than iPMS = ENU = DEN = ENNG. When the percentage of lethal mutations induced in mei-9L1 females are plotted against those determined for control females, straight lines of different slopes are obtained. These mei-9L1/mei-9+ indices are: MMS = 7.6, MNU = 5.4, DMN = 2.4, EMS = 2.4 and iPMS = ENU = DEN = ENNG = 1. An identical order of hypermutability with similar indices is obtained for the mus(2)201 mutants: MMS(7.3) greater than MNU (5.4) greater than EMS(2.0) greater than ENU(1.1). Thus, absence of excision repair function has a significant effect on mutation production by AAs efficient in alkylating N-atoms in DNA but no measurable influence on mutation production by AAs most efficient in

Effect of ionic strength and cationic DNA affinity binders on the DNA sequence selective alkylation of guanine N7-positions by nitrogen mustards

International Nuclear Information System (INIS)

Hartley, J.A.; Forrow, S.M.; Souhami, R.L.

1990-01-01

Large variations in alkylation intensities exist among guanines in a DNA sequence following treatment with chemotherapeutic alkylating agents such as nitrogen mustards, and the substituent attached to the reactive group can impose a distinct sequence preference for reaction. In order to understand further the structural and electrostatic factors which determine the sequence selectivity of alkylation reactions, the effect of increase ionic strength, the intercalator ethidium bromide, AT-specific minor groove binders distamycin A and netropsin, and the polyamine spermine on guanine N7-alkylation by L-phenylalanine mustard (L-Pam), uracil mustard (UM), and quinacrine mustard (QM) was investigated with a modification of the guanine-specific chemical cleavage technique for DNA sequencing. The result differed with both the nitrogen mustard and the cationic agent used. The effect, which resulted in both enhancement and suppression of alkylation sites, was most striking in the case of netropsin and distamycin A, which differed from each other. DNA footprinting indicated that selective binding to AT sequences in the minor groove of DNA can have long-range effects on the alkylation pattern of DNA in the major groove

Protection of hematopoietic cells from O(6)-alkylation damage by O(6)-methylguanine DNA methyltransferase gene transfer: studies with different O(6)-alkylating agents and retroviral backbones.

Science.gov (United States)

Jansen, M; Bardenheuer, W; Sorg, U R; Seeber, S; Flasshove, M; Moritz, T

2001-07-01

Overexpression of O(6)-methylguanine DNA methyltransferase (MGMT) can protect hematopoietic cells from O(6)-alkylation damage. To identify possible clinical applications of this technology we compared the effect of MGMT gene transfer on the hematotoxicity induced by different O(6)-alkylating agents in clinical use: the chloroethylnitrosoureas ACNU, BCNU, CCNU and the tetrazine derivative temozolomide. In addition, various retroviral vectors expressing the MGMT-cDNA were investigated to identify optimal viral backbones for hematoprotection by MGMT expression. Protection from ACNU, BCNU, CCNU or temozolomide toxicity was evaluated utilizing a Moloney murine leukemia virus-based retroviral vector (N2/Zip-PGK-MGMT) to transduce primary murine bone marrow cells. Increased resistance in murine colony-forming units (CFU) was demonstrated for all four drugs. In comparison to mock-transduced controls, after transduction with N2/Zip-PGK-MGMT the IC50 for CFU increased on average 4.7-fold for ACNU, 2.5-fold for BCNU, 6.3-fold for CCNU and 1.5-fold for temozolomide. To study the effect of the retroviral backbone on hematoprotection various vectors expressing the human MGMT-cDNA from a murine embryonic sarcoma virus LTR (MSCV-MGMT) or a hybrid spleen focus-forming/murine embryonic sarcoma virus LTR (SF1-MGMT) were compared with the N2/Zip-PGK-MGMT vector. While all vectors increased resistance of transduced human CFU to ACNU, the SF1-MGMT construct was most efficient especially at high ACNU concentrations (8-12 microg/ml). Similar results were obtained for protection of murine high-proliferative-potential colony-forming cells. These data may help to optimize treatment design and retroviral constructs in future clinical studies aiming at hematoprotection by MGMT gene transfer.

Ionic liquid and solid HF equivalent amine-poly(hydrogen fluoride) complexes effecting efficient environmentally friendly isobutane-isobutylene alkylation.

Science.gov (United States)

Olah, George A; Mathew, Thomas; Goeppert, Alain; Török, Béla; Bucsi, Imre; Li, Xing-Ya; Wang, Qi; Marinez, Eric R; Batamack, Patrice; Aniszfeld, Robert; Prakash, G K Surya

2005-04-27

Isoparaffin-olefin alkylation was investigated using liquid as well as solid onium poly(hydrogen fluoride) catalysts. These new immobilized anhydrous HF catalysts contain varied amines and nitrogen-containing polymers as complexing agents. The liquid poly(hydrogen fluoride) complexes of amines are typical ionic liquids, which are convenient media and serve as HF equivalent catalysts with decreased volatility for isoparaffin-olefin alkylation. Polymeric solid amine:poly(hydrogen fluoride) complexes are excellent solid HF equivalents for similar alkylation acid catalysis. Isobutane-isobutylene or 2-butene alkylation gave excellent yields of high octane alkylates (up to RON = 94). Apart from their excellent catalytic performance, the new catalyst systems significantly reduce environmental hazards due to the low volatility of complexed HF. They represent a new, "green" class of catalyst systems for alkylation reactions, maintaining activity of HF while minimizing its environmental hazards.

Genomic phenotyping by barcode sequencing broadly distinguishes between alkylating agents, oxidizing agents, and non-genotoxic agents, and reveals a role for aromatic amino acids in cellular recovery after quinone exposure.

Science.gov (United States)

Svensson, J Peter; Quirós Pesudo, Laia; McRee, Siobhan K; Adeleye, Yeyejide; Carmichael, Paul; Samson, Leona D

2013-01-01

Toxicity screening of compounds provides a means to identify compounds harmful for human health and the environment. Here, we further develop the technique of genomic phenotyping to improve throughput while maintaining specificity. We exposed cells to eight different compounds that rely on different modes of action: four genotoxic alkylating (methyl methanesulfonate (MMS), N-Methyl-N-nitrosourea (MNU), N,N'-bis(2-chloroethyl)-N-nitroso-urea (BCNU), N-ethylnitrosourea (ENU)), two oxidizing (2-methylnaphthalene-1,4-dione (menadione, MEN), benzene-1,4-diol (hydroquinone, HYQ)), and two non-genotoxic (methyl carbamate (MC) and dimethyl sulfoxide (DMSO)) compounds. A library of S. cerevisiae 4,852 deletion strains, each identifiable by a unique genetic 'barcode', were grown in competition; at different time points the ratio between the strains was assessed by quantitative high throughput 'barcode' sequencing. The method was validated by comparison to previous genomic phenotyping studies and 90% of the strains identified as MMS-sensitive here were also identified as MMS-sensitive in a much lower throughput solid agar screen. The data provide profiles of proteins and pathways needed for recovery after both genotoxic and non-genotoxic compounds. In addition, a novel role for aromatic amino acids in the recovery after treatment with oxidizing agents was suggested. The role of aromatic acids was further validated; the quinone subgroup of oxidizing agents were extremely toxic in cells where tryptophan biosynthesis was compromised.

The Fanconi anemia pathway sensitizes to DNA alkylating agents by inducing JNK-p53-dependent mitochondrial apoptosis in breast cancer cells.

Science.gov (United States)

Zhao, Lin; Li, Yanlin; He, Miao; Song, Zhiguo; Lin, Shu; Yu, Zhaojin; Bai, Xuefeng; Wang, Enhua; Wei, Minjie

2014-07-01

The Fanconi anemia/BRCA (FA/BRCA) DNA damage repair pathway plays a pivotal role in the cellular response to DNA alkylating agents and greatly influences drug response in cancer treatment. However, the molecular mechanisms underlying the FA/BRCA pathway reversed resistance have received limited attention. In the present study, we investigated the effect of Fanconi anemia complementation group F protein (FANCF), a critical factor of the FA/BRCA pathway, on cancer cell apoptosis induced by DNA alkylating agents such as mitomycin c (MMC). We found that FANCF shRNA potentiated MMC-induced cytotoxicity and apoptosis in MCF-7 and MDA-MB-231 breast cancer cells. At a mechanistic level, FANCF shRNA downregulated the anti-apoptotic protein Bcl-2 and upregulated the pro-apoptotic protein Bax, accompanied by release of cyt-c and smac into the cytosol in MMC-treated cells. Furthermore, activation of caspase-3 and -9, other than caspase-8, cleavage of poly(ADP ribose) polymerase (PARP), and a decrease of mitochondrial membrane potential (MMP) indicated that involvement of the mitochondrial apoptotic pathway in FANCF silencing of MMC-treated breast cancer cells. A decrease in IAP family proteins XIAP and survivin were also observed following FANCF silencing in MMC-treated breast cancer cells. Notably, FANCF shRNA was able to increase p53 levels through activation of the JNK pathway in MMC-treated breast cancer cells. Furthermore, p53 inhibition using pifithrin-α abolished the induction of caspase-3 and PARP by FANCF shRNA and MMC, indicating that MMC-induced apoptosis is substantially enhanced by FANCF shRNA via p53-dependent mechanisms. To our knowledge, we provide new evidence for the potential application of FANCF as a chemosensitizer in breast cancer therapy.

Oxidants and not alkylating agents induce rapid mtDNA loss and mitochondrial dysfunction

Science.gov (United States)

Furda, Amy M.; Marrangoni, Adele M.; Lokshin, Anna; Van Houten, Bennett

2013-01-01

Mitochondrial DNA (mtDNA) is essential for proper mitochondrial function and encodes 22 tRNAs, 2 rRNAs and 13 polypeptides that make up subunits of complex I, III, IV, in the electron transport chain and complex V, the ATP synthase. Although mitochondrial dysfunction has been implicated in processes such as premature aging, neurodegeneration, and cancer, it has not been shown whether persistent mtDNA damage causes a loss of oxidative phosphorylation. We addressed this question by treating mouse embryonic fibroblasts with either hydrogen peroxide (H2O2) or the alkylating agent methyl methanesulfonate (MMS) and measuring several endpoints, including mtDNA damage and repair rates using QPCR, levels of mitochondrial- and nuclear-encoded proteins using antibody analysis, and a pharmacologic profile of mitochondria using the Seahorse Extracellular Flux Analyzer. We show that a 60 min treatment with H2O2 causes persistent mtDNA lesions, mtDNA loss, decreased levels of a nuclear-encoded mitochondrial subunit, a loss of ATP-linked oxidative phosphorylation and a loss of total reserve capacity. Conversely, a 60 min treatment with 2 mM MMS causes persistent mtDNA lesions but no mtDNA loss, no decrease in levels of a nuclear-encoded mitochondrial subunit, and no mitochondrial dysfunction. These results suggest that persistent mtDNA damage is not sufficient to cause mitochondrial dysfunction. PMID:22766155

In vitro sensitivity of normal and hereditary retinoblastoma fibroblasts to DNA-damaging agents

International Nuclear Information System (INIS)

Woods, W.G.; Byrne, T.D.

1986-01-01

We investigated the ability of nine fibroblast cell strains from patients with the hereditary form of retinoblastoma (RB) to handle various types of DNA-damaging agents and compared the results with those obtained in nine normal strains. Cell strains were exposed to gamma-radiation, which causes DNA scission; actinomycin D, a DNA-intercalating agent; and mitomycin C, a bifunctional alkylating agent leading to DNA-DNA cross-linking. Cell strains were studied for their ability to survive in a cytotoxicity assay. Nine normal strains exhibited a mean D0 (inverse of the slope of the straight line portion of the survival curve) of 134-178 cGy after radiation exposure, compared to a range of 119-186 cGy in the nine RB strains (P = 0.33). Similarly, exposure to actinomycin D led to D0 values of 0.024-0.069 microgram/ml in the nine normal strains and D0 values of 0.016-0.067 microgram/ml in the RB strains (P = 0.64). The nine RB strains did exhibit a small overall increase in sensitivity after exposure to mitomycin C, with D0 values ranging from 0.14-0.32 microgram/ml versus 0.19-0.66 microgram/ml in the nine normal strains (P = 0.002); however, when the two most resistant normal strains were excluded from analysis, results were similar. Three RB cell strains derived from individuals who had either developed second cancers or who had a family history of additional sarcomas consistently exhibited increases in sensitivity to all three DNA-damaging agents studied compared with other hereditary RB cell strains as well as normal strains. The results suggest that normal human fibroblast cell strains exhibit a wide response to DNA-damaging agents, especially chemical agents. Most hereditary RB strains exhibit sensitivity well within the normal range; however, strains from RB patients predisposed to second cancers exhibit increases in sensitivity to DNA-damaging agents

Bifunctional organocatalysts for the asymmetric synthesis of axially chiral benzamides

Directory of Open Access Journals (Sweden)

Ryota Miyaji

2017-08-01

Full Text Available Bifunctional organocatalysts bearing amino and urea functional groups in a chiral molecular skeleton were applied to the enantioselective synthesis of axially chiral benzamides via aromatic electrophilic bromination. The results demonstrate the versatility of bifunctional organocatalysts for the enantioselective construction of axially chiral compounds. Moderate to good enantioselectivities were afforded with a range of benzamide substrates. Mechanistic investigations were also carried out.

Isobutane/olefin-alkylation

Energy Technology Data Exchange (ETDEWEB)

Waitkamp, J.; Maixner, S.

1983-11-01

Isobutane/olefin-alkylation - technology and reaction mechanism of a refinery process for production of high octane gasoline components: The alkylation of i-butane with olefins, especially with butenes, is a process for the conversion of light byproducts of a catalytic cracker to high quality gasoline components. Alkylate is a complex mixture of i-paraffins containing 5 to ca. 12 carbon atoms. Due to their octane numbers the four trimethylpentane isomers are the most desirable product components. Indeed, under optimum process conditions these isomers are the main products. Presently, alkylation capacity in the western world amounts to more than 40x10/sup 6/ t/a. Most units are located in the USA. Two liquid-phase processes using sulfuric acid and hydrofluoric acid, respectively, are of commercial importance. At present, there is a definite trend towards HF-alkylation. The reaction mechanism which proceeds via carbocations, is extremely complex. It is composed of a great variety of individual steps. Modern mechanistic concepts are discussed.

Sequence-selective single-molecule alkylation with a pyrrole-imidazole polyamide visualized in a DNA nanoscaffold.

Science.gov (United States)

Yoshidome, Tomofumi; Endo, Masayuki; Kashiwazaki, Gengo; Hidaka, Kumi; Bando, Toshikazu; Sugiyama, Hiroshi

2012-03-14

We demonstrate a novel strategy for visualizing sequence-selective alkylation of target double-stranded DNA (dsDNA) using a synthetic pyrrole-imidazole (PI) polyamide in a designed DNA origami scaffold. Doubly functionalized PI polyamide was designed by introduction of an alkylating agent 1-(chloromethyl)-5-hydroxy-1,2-dihydro-3H-benz[e]indole (seco-CBI) and biotin for sequence-selective alkylation at the target sequence and subsequent streptavidin labeling, respectively. Selective alkylation of the target site in the substrate DNA was observed by analysis using sequencing gel electrophoresis. For the single-molecule observation of the alkylation by functionalized PI polyamide using atomic force microscopy (AFM), the target position in the dsDNA (∼200 base pairs) was alkylated and then visualized by labeling with streptavidin. Newly designed DNA origami scaffold named "five-well DNA frame" carrying five different dsDNA sequences in its cavities was used for the detailed analysis of the sequence-selectivity and alkylation. The 64-mer dsDNAs were introduced to five individual wells, in which target sequence AGTXCCA/TGGYACT (XY = AT, TA, GC, CG) was employed as fully matched (X = G) and one-base mismatched (X = A, T, C) sequences. The fully matched sequence was alkylated with 88% selectivity over other mismatched sequences. In addition, the PI polyamide failed to attach to the target sequence lacking the alkylation site after washing and streptavidin treatment. Therefore, the PI polyamide discriminated the one mismatched nucleotide at the single-molecule level, and alkylation anchored the PI polyamide to the target dsDNA.

Genomic phenotyping by barcode sequencing broadly distinguishes between alkylating agents, oxidizing agents, and non-genotoxic agents, and reveals a role for aromatic amino acids in cellular recovery after quinone exposure.

Directory of Open Access Journals (Sweden)

J Peter Svensson

Full Text Available Toxicity screening of compounds provides a means to identify compounds harmful for human health and the environment. Here, we further develop the technique of genomic phenotyping to improve throughput while maintaining specificity. We exposed cells to eight different compounds that rely on different modes of action: four genotoxic alkylating (methyl methanesulfonate (MMS, N-Methyl-N-nitrosourea (MNU, N,N'-bis(2-chloroethyl-N-nitroso-urea (BCNU, N-ethylnitrosourea (ENU, two oxidizing (2-methylnaphthalene-1,4-dione (menadione, MEN, benzene-1,4-diol (hydroquinone, HYQ, and two non-genotoxic (methyl carbamate (MC and dimethyl sulfoxide (DMSO compounds. A library of S. cerevisiae 4,852 deletion strains, each identifiable by a unique genetic 'barcode', were grown in competition; at different time points the ratio between the strains was assessed by quantitative high throughput 'barcode' sequencing. The method was validated by comparison to previous genomic phenotyping studies and 90% of the strains identified as MMS-sensitive here were also identified as MMS-sensitive in a much lower throughput solid agar screen. The data provide profiles of proteins and pathways needed for recovery after both genotoxic and non-genotoxic compounds. In addition, a novel role for aromatic amino acids in the recovery after treatment with oxidizing agents was suggested. The role of aromatic acids was further validated; the quinone subgroup of oxidizing agents were extremely toxic in cells where tryptophan biosynthesis was compromised.

Alkylation induced cerebellar degeneration dependent on Aag and Parp1 does not occur via previously established cell death mechanisms.

Directory of Open Access Journals (Sweden)

Carrie M Margulies

Full Text Available Alkylating agents are ubiquitous in our internal and external environments, causing DNA damage that contributes to mutations and cell death that can result in aging, tissue degeneration and cancer. Repair of methylated DNA bases occurs primarily through the base excision repair (BER pathway, a multi-enzyme pathway initiated by the alkyladenine DNA glycosylase (Aag, also known as Mpg. Previous work demonstrated that mice treated with the alkylating agent methyl methanesulfonate (MMS undergo cerebellar degeneration in an Aag-dependent manner, whereby increased BER initiation by Aag causes increased tissue damage that is dependent on activation of poly (ADP-ribose polymerase 1 (Parp1. Here, we dissect the molecular mechanism of cerebellar granule neuron (CGN sensitivity to MMS using primary ex vivo neuronal cultures. We first established a high-throughput fluorescent imaging method to assess primary neuron sensitivity to treatment with DNA damaging agents. Next, we verified that the alkylation sensitivity of CGNs is an intrinsic phenotype that accurately recapitulates the in vivo dependency of alkylation-induced CGN cell death on Aag and Parp1 activity. Finally, we show that MMS-induced CGN toxicity is independent of all the cellular events that have previously been associated with Parp-mediated toxicity, including mitochondrial depolarization, AIF translocation, calcium fluxes, and NAD+ consumption. We therefore believe that further investigation is needed to adequately describe all varieties of Parp-mediated cell death.

Alkylation induced cerebellar degeneration dependent on Aag and Parp1 does not occur via previously established cell death mechanisms.

Science.gov (United States)

Margulies, Carrie M; Chaim, Isaac Alexander; Mazumder, Aprotim; Criscione, June; Samson, Leona D

2017-01-01

Alkylating agents are ubiquitous in our internal and external environments, causing DNA damage that contributes to mutations and cell death that can result in aging, tissue degeneration and cancer. Repair of methylated DNA bases occurs primarily through the base excision repair (BER) pathway, a multi-enzyme pathway initiated by the alkyladenine DNA glycosylase (Aag, also known as Mpg). Previous work demonstrated that mice treated with the alkylating agent methyl methanesulfonate (MMS) undergo cerebellar degeneration in an Aag-dependent manner, whereby increased BER initiation by Aag causes increased tissue damage that is dependent on activation of poly (ADP-ribose) polymerase 1 (Parp1). Here, we dissect the molecular mechanism of cerebellar granule neuron (CGN) sensitivity to MMS using primary ex vivo neuronal cultures. We first established a high-throughput fluorescent imaging method to assess primary neuron sensitivity to treatment with DNA damaging agents. Next, we verified that the alkylation sensitivity of CGNs is an intrinsic phenotype that accurately recapitulates the in vivo dependency of alkylation-induced CGN cell death on Aag and Parp1 activity. Finally, we show that MMS-induced CGN toxicity is independent of all the cellular events that have previously been associated with Parp-mediated toxicity, including mitochondrial depolarization, AIF translocation, calcium fluxes, and NAD+ consumption. We therefore believe that further investigation is needed to adequately describe all varieties of Parp-mediated cell death.

Quantitative PCR analysis of diepoxybutane and epihalohydrin damage to nuclear versus mitochondrial DNA

Energy Technology Data Exchange (ETDEWEB)

LaRiviere, Frederick J. [Department of Chemistry, Washington and Lee University, Lexington, VA 24450 (United States); Newman, Adam G.; Watts, Megan L.; Bradley, Sharonda Q.; Juskewitch, Justin E. [Department of Chemistry, Colby College, 5757 Mayflower Hill Drive, Waterville, ME 04901 (United States); Greenwood, Paul G. [Department of Biology, Colby College, Waterville, ME 04901 (United States); Millard, Julie T., E-mail: jtmillar@colby.edu [Department of Chemistry, Colby College, 5757 Mayflower Hill Drive, Waterville, ME 04901 (United States)

2009-05-12

The bifunctional alkylating agents diepoxybutane (DEB) and epichlorohydrin (ECH) are linked to the elevated incidence of certain cancers among workers in the synthetic polymer industry. Both compounds form interstrand cross-links within duplex DNA, an activity suggested to contribute to their cytotoxicity. To assess the DNA targeting of these compounds in vivo, we assayed for damage within chicken erythro-progenitor cells at three different sites: one within mitochondrial DNA, one within expressed nuclear DNA, and one within unexpressed nuclear DNA. We determined the degree of damage at each site via a quantitative polymerase chain reaction, which compares amplification of control, untreated DNA to that from cells exposed to the agent in question. We found that ECH and the related compound epibromohydrin preferentially target nuclear DNA relative to mitochondrial DNA, whereas DEB reacts similarly with the two genomes. Decreased reactivity of the mitochondrial genome could contribute to the reduced apoptotic potential of ECH relative to DEB. Additionally, formation of lesions by all agents occurred at comparable levels for unexpressed and expressed nuclear loci, suggesting that alkylation is unaffected by the degree of chromatin condensation.

Quantitative PCR analysis of diepoxybutane and epihalohydrin damage to nuclear versus mitochondrial DNA

International Nuclear Information System (INIS)

LaRiviere, Frederick J.; Newman, Adam G.; Watts, Megan L.; Bradley, Sharonda Q.; Juskewitch, Justin E.; Greenwood, Paul G.; Millard, Julie T.

2009-01-01

The bifunctional alkylating agents diepoxybutane (DEB) and epichlorohydrin (ECH) are linked to the elevated incidence of certain cancers among workers in the synthetic polymer industry. Both compounds form interstrand cross-links within duplex DNA, an activity suggested to contribute to their cytotoxicity. To assess the DNA targeting of these compounds in vivo, we assayed for damage within chicken erythro-progenitor cells at three different sites: one within mitochondrial DNA, one within expressed nuclear DNA, and one within unexpressed nuclear DNA. We determined the degree of damage at each site via a quantitative polymerase chain reaction, which compares amplification of control, untreated DNA to that from cells exposed to the agent in question. We found that ECH and the related compound epibromohydrin preferentially target nuclear DNA relative to mitochondrial DNA, whereas DEB reacts similarly with the two genomes. Decreased reactivity of the mitochondrial genome could contribute to the reduced apoptotic potential of ECH relative to DEB. Additionally, formation of lesions by all agents occurred at comparable levels for unexpressed and expressed nuclear loci, suggesting that alkylation is unaffected by the degree of chromatin condensation.

Kit for preparing a technetium-99m myocardial imaging agent

International Nuclear Information System (INIS)

Woulfe, S.R.; Deutsch, E.A.; Dyszlewski, M.; Neumann, W.L.

1992-01-01

This patent describes a kit for preparing a technetium 99m myocardial imaging agent. It comprises a first vial containing a lyophilized pyrogen free, sterile mixture of an effective reducing agent and a first ligand having the following general formula: wherein the R 1 groups may be the same or different and are selected from the group consisting of hydrogen, hydroxy, C 1 - C 5 alkyl, C 1 - C 5 alkyl substituted by hydroxyl, ether, ester, amide, ketone, aldehyde and nitrile; the R 2 groups may be the same or different and are selected from the group consisting of hydrogen, hydroxy, C 1 - C 5 alkyl, C 1 - C 5 alkyl substituted by hydroxyl, ether, ester, amide, ketone, aldehyde, and nitrile; the X and Y groups may be the same or different and are selected from the group consisting of oxygen and sulfur; and n is equal to 1 or 2; and a second vial containing a lyophilized pyrogen free, sterile protected salt of a phosphine ligand

S-alkylation of soft scorpionates.

Science.gov (United States)

Rajasekharan-Nair, Rajeev; Moore, Dean; Chalmers, Kirsten; Wallace, Dawn; Diamond, Louise M; Darby, Lisa; Armstrong, David R; Reglinski, John; Spicer, Mark D

2013-02-11

The alkylation reactions of soft scorpionates are reported. The hydrotris(S-alkyl-methimazolyl)borate dications (alkyl = methyl, allyl, benzyl), which were prepared by the reaction of Tm(Me) anion and primary alkyl halides, have been isolated and structurally characterised. The reaction is, however, not universally successful. DFT analysis of these alkylation reactions (C=S versus B-H alkylation) indicates that the observed outcome is driven by kinetic factors. Extending the study to incorporate alternative imine thiones (mercaptobenzothiazole, bz; thiazoline, tz) led to the structural characterisation of di[aquo-μ-aquohydrotris(mercaptobenzothiazolyl)boratosodium], which contains sodium atoms in the κ(3)-S,S,S coordination mode. Alkylation of Na[Tbz] and Na[tzTtz] leads to decomposition resulting in the formation of the simple S-alkylated heterocycles. The analysis of the species involved in these reactions shows an inherent weakness in the B-N bond in soft scorpionates, which has implications for their use in more advanced chemistry. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanosheet Supported Single-Metal Atom Bifunctional Catalyst for Overall Water Splitting.

Science.gov (United States)

Ling, Chongyi; Shi, Li; Ouyang, Yixin; Zeng, Xiao Cheng; Wang, Jinlan

2017-08-09

Nanosheet supported single-atom catalysts (SACs) can make full use of metal atoms and yet entail high selectivity and activity, and bifunctional catalysts can enable higher performance while lowering the cost than two separate unifunctional catalysts. Supported single-atom bifunctional catalysts are therefore of great economic interest and scientific importance. Here, on the basis of first-principles computations, we report a design of the first single-atom bifunctional eletrocatalyst, namely, isolated nickel atom supported on β 12 boron monolayer (Ni 1 /β 12 -BM), to achieve overall water splitting. This nanosheet supported SAC exhibits remarkable electrocatalytic performance with the computed overpotential for oxygen/hydrogen evolution reaction being just 0.40/0.06 V. The ab initio molecular dynamics simulation shows that the SAC can survive up to 800 K elevated temperature, while enacting a high energy barrier of 1.68 eV to prevent isolated Ni atoms from clustering. A viable experimental route for the synthesis of Ni 1 /β 12 -BM SAC is demonstrated from computer simulation. The desired nanosheet supported single-atom bifunctional catalysts not only show great potential for achieving overall water splitting but also offer cost-effective opportunities for advancing clean energy technology.

Alkylation of isobutane with light olefins: Yields of alkylates for different olefins

Energy Technology Data Exchange (ETDEWEB)

Albright, L.F. [Purdue Univ., West Lafayette, IN (United States); Kranz, K.E.; Masters, K.R. [STRATCO, Inc., Leawood, KS (United States)

1993-12-01

For alkylation of isobutane with C{sub 3}-C{sub 5} olefins using sulfuric acid as the catalyst, the yields of alkylates with different olefins are compared as the operating conditions are changed. The results of recent pilot plant experiments with propylene, C{sub 4} olefins, and C{sub 5} olefins permit such comparisons. The yields expressed as weight of alkylate produced per 100 wt of olefin consumed varied from about 201:100 to 220:100. Weight ratios of the isobutane consumed per olefin consumed vary from about 101:100 to 120:100. differences of yield values are explained by the changes in the overall chemistry. The procedure employed to calculate yields with good accuracy is based on the analysis of the alkylate and the amount of conjunct polymers produced. Based on literature data, yields are also reported for alkylations using HF as the catalyst.

Literature Survey and Further Studies on the 3-Alkylation of N-Unprotected 3-Monosubstituted Oxindoles. Practical Synthesis of N-Unprotected 3,3-Disubstituted Oxindoles and Subsequent Transformations on the Aromatic Ring.

Science.gov (United States)

Kókai, Eszter; Simig, Gyula; Volk, Balázs

2016-12-26

The paper provides a comprehensive review of the base-catalysed C3-alkylation of N-unprotected-3-monosubstituted oxindoles. Based on a few, non-systematic studies described in the literature using butyllithium as the deprotonating agent, an optimized method has now been elaborated, via the corresponding lithium salt, for the selective C3-alkylation of this family of compounds. The optimal excess of butyllithium and alkylating agent, and the role of the halogen atom in the latter (alkyl bromides vs. iodides) were also studied. The alkylation protocol has also been extended to some derivatives substituted at the aromatic ring. Finally, various substituents were introduced into the aromatic ring of the N-unprotected 3,3-dialkyloxindoles obtained by this optimized method.

Literature Survey and Further Studies on the 3-Alkylation of N-Unprotected 3-Monosubstituted Oxindoles. Practical Synthesis of N-Unprotected 3,3-Disubstituted Oxindoles and Subsequent Transformations on the Aromatic Ring

Directory of Open Access Journals (Sweden)

Eszter Kókai

2016-12-01

Full Text Available The paper provides a comprehensive review of the base-catalysed C3-alkylation of N-unprotected-3-monosubstituted oxindoles. Based on a few, non-systematic studies described in the literature using butyllithium as the deprotonating agent, an optimized method has now been elaborated, via the corresponding lithium salt, for the selective C3-alkylation of this family of compounds. The optimal excess of butyllithium and alkylating agent, and the role of the halogen atom in the latter (alkyl bromides vs. iodides were also studied. The alkylation protocol has also been extended to some derivatives substituted at the aromatic ring. Finally, various substituents were introduced into the aromatic ring of the N-unprotected 3,3-dialkyloxindoles obtained by this optimized method.

N-Alkylation Using Sodium Triacetoxyborohydride with Carboxylic Acids as Alkyl Sources.

Science.gov (United States)

Tamura, Satoru; Sato, Keigo; Kawano, Tomikazu

2018-01-01

A versatile N-alkylation was performed using sodium triacetoxyborohydride and carboxylic acid as an alkyl source. The combination of these reagents furnished products different from those given previously by a similar reaction. Moreover, the mild conditions of our method allowed some functional groups to remain through the reaction, whereas they would react and be converted into other moieties in the similar reductive N-alkylation reported previously. Herein, we provide a new procedure for the preparation of various compounds containing nitrogen atoms.

Fat & fabulous: bifunctional lipids in the spotlight.

Science.gov (United States)

Haberkant, Per; Holthuis, Joost C M

2014-08-01

Understanding biological processes at the mechanistic level requires a systematic charting of the physical and functional links between all cellular components. While protein-protein and protein-nucleic acid networks have been subject to many global surveys, other critical cellular components such as membrane lipids have rarely been studied in large-scale interaction screens. Here, we review the development of photoactivatable and clickable lipid analogues-so-called bifunctional lipids-as novel chemical tools that enable a global profiling of lipid-protein interactions in biological membranes. Recent studies indicate that bifunctional lipids hold great promise in systematic efforts to dissect the elaborate crosstalk between proteins and lipids in live cells and organisms. This article is part of a Special Issue entitled Tools to study lipid functions. Copyright © 2014 Elsevier B.V. All rights reserved.

Mechanish of dTTP Inhibition of the Bifunctional dCTP Deaminase:dUTPase Encoded by Mycobacterium tuberculosis

DEFF Research Database (Denmark)

Helt, Signe Smedegaard; Thymark, Majbritt; Harris, Pernille

2008-01-01

Recombinant deoxycytidine triphosphate (dCTP) deaminase from Mycobacterium tuberculosis was produced in Escherichia coli and purified. The enzyme proved to be a bifunctional dCTP deaminase:deoxyuridine triphosphatase. As such, the M. tuberculosis enzyme is the second bifunctional enzyme to be cha......Recombinant deoxycytidine triphosphate (dCTP) deaminase from Mycobacterium tuberculosis was produced in Escherichia coli and purified. The enzyme proved to be a bifunctional dCTP deaminase:deoxyuridine triphosphatase. As such, the M. tuberculosis enzyme is the second bifunctional enzyme...

Enzymatic Analysis of G- and V-Agents and Their Degradation Products

National Research Council Canada - National Science Library

Elashvili, Ilya

2003-01-01

.... The nerve agents can be hydrolyzed to their respective methylphosphonate alkyl ester (h-agent) products by alkali treatment or by specific hydrolytic enzymes, such as organophosphorus hydrolase...

Comparative Evaluation of Using NOTA and DOTA Derivatives as Bifunctional Chelating Agents in the Preparation of 68Ga-Labeled Porphyrin: Impact on Pharmacokinetics and Tumor Uptake in a Mouse Model.

Science.gov (United States)

Guleria, Mohini; Das, Tapas; Amirdhanayagam, Jeyachitra; Sarma, Haladhar D; Dash, Ashutosh

2018-02-01

Both NOTA (1,4,7-triazacyclononane-1,4,7-triacetic acid) and DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) derivatives have been used as bifunctional chelating agents (BFCAs) for the preparation of 68 Ga-labeled target-specific agents having potential for positron emission tomography (PET) imaging of cancerous lesions. In the present work, the authors have attempted a comparative pharmacokinetic evaluation between 68 Ga-labeled porphyrins prepared using NOTA and DOTA derivatives as the BFCAs. A symmetrical porphyrin derivative, 5,10,15,20-tetrakis(p-carboxymethyleneoxyphenyl)porphyrin, was synthesized and coupled with two different BFCAs viz. p-NH 2 -benzyl-NOTA and p-NH 2 -benzyl-DOTA. Both the porphyrin-BFCA conjugates were radiolabeled with 68 Ga. A comparative bioevaluation involving pharmacokinetics and tumor affinity was performed in a tumor-bearing small animal model. Gallium-68-labeled porphyrin-amido-benzyl-NOTA and porphyrin-amido-benzyl-DOTA complexes were prepared with high radiochemical purity. Both radiolabeled complexes exhibited almost similar stability in human serum and near-identical tumor affinity and pharmacokinetic behavior in animal studies. The present study demonstrates that the pharmacokinetic behavior of 68 Ga-labeled porphyrin derivatives, prepared using either NOTA or DOTA derivatives as BFCAs, remains almost identical and hence both NOTA and DOTA derivatives could be considered equivalent for developing 68 Ga-based PET agents for imaging of tumorous lesions.

Effects of inhibitors of DNA repair on the frequencies of chromosomal aberrations induced by x-rays or alkylating agents in cultured human lymphocytes

International Nuclear Information System (INIS)

Kihlman, B.A.; Andersson, H.C.

1986-01-01

In the first part of this presentation the authors give examples of the synergistic enhancements that are obtained with various inhibitor combinations in G/sub 2/. The second part of the presentation deals with the effects of two agents, also well known for their capacity to potentiate the frequency of chromosomal aberrations induced by physical and chemical agents, but with a different mechanism of action. These agents are caffeine and 3-aminobenzamide (3AB). Caffeine has for decades been used as an inhibitor of DNA repair although its mechanism of action has not been fully understood. 3AB has more recently come into focus as an efficient inhibitor of the synthesis of poly-(ADP-ribose), a substance believed to be of importance in connection with the repair of certain types of DNA damage. The results presented do not quite fit in with the general idea about the mode of action of these agents. All experiments were carried out with whole-blood cultures of human lymphocytes. When inhibitors were used as post-treatments, chromosomal aberrations were induced by X-rays or by the alkylating agents thiotepa (TT) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). X-rays were generated by a Siemens Stabilipan 200 apparatus, at a dose rate of 0.5 Gy/min. The tube (TR 200f) was operated at 180 kV, 10 mA and the radiation filtered through 4 mm Al

Electrochemistry of potentially bioreductive alkylating quinones. Part 3. Quantitative structure-electrochemistry relationships of aziridinylquinones

NARCIS (Netherlands)

Driebergen, R.J.; Moret, E.E.; Janssen, L.H.M.; Blauw, J.S.; Holthuis, J.J.M.; Postma kelder, S.J.; Verboom, Willem; Reinhoudt, David; van der Linden, W.E.

1992-01-01

The concept of bioreductive alkylation as a mechanism of action of aziridinylquinoid anticancer agents has been investigated by the use of electrochemical techniques. Properly substituted aziridinylquinones are activated by an electrochemical step (reduction of the quinone function), followed by

Main regularities of radiolytic transformations of bifunctional organic compounds

International Nuclear Information System (INIS)

Petryaev, E.P.; Shadyro, O.I.

1985-01-01

General regularities of the radiolysis of bifunctional organic compounds (α-diols, ethers of α-diols, amino alcohols, hydroxy aldehydes and hydroxy asids) in aqueous solutions from the early stages of the process to formation of finite products are traced. It is pointed out that the most characteristic course of radiation-chemical, transformation of bifunctional compounds in agueous solutions in the fragmentation process with monomolecular decomposition of primary radicals of initial substrances and simultaneous scission of two vicinal in respect to radical centre bonds via five-membered cyclic transient state. The data obtained are of importance for molecular radiobiology

New potential of the reductive alkylation of amines

International Nuclear Information System (INIS)

Gusak, K N; Ignatovich, Zh V; Koroleva, E V

2015-01-01

Available data on the reductive alkylation of amines with carbonyl compounds — a key method for the preparation of secondary and tertiary amines — are described systematically. The review provides information on the relevant reducing agents and catalysts and on the use of chiral catalysts in stereo- and enantiocontrolled reactions of amine synthesis. The effect of the reactant and catalyst structures on the reaction rates and chemo- and stereo(enantio)selectivity is considered. The bibliography includes 156 references

Alkyl and aryl phosphorodiiodidites. Pt. 2

International Nuclear Information System (INIS)

Feshchenko, N.G.; Kostina, V.G.

1976-01-01

Alkyl phosphorodiiodidites are formed in the reactions of alkyl phosphorodichloridites with lithium iodide. They are stable at -60 to -50 0 . When warmed to 20 0 , they disproportionate with conversion into trialkyl phosphites and phosphorus triiodide. The latter also react together and give alkyl iodides, diphosphorus tetraiodide, and a polymer of unestablished structure. Diaryl and dialkyl phosphoriodidites are stable only in solution at low temperatures. They disproportionate in a similar way to aryl and alkyl phosphorodiiodidites. Alkyl phosphorodiiodidites react with iodine with the formation of alkyl iodides and phosphoryl iodide

Photoinduced alkylation reactions

Energy Technology Data Exchange (ETDEWEB)

Dondi, D.; Fagnoni, M.; Albini, A.

2002-07-01

Some {alpha}{beta}-unsaturated aldehydes have been alkylated generating alkyl radicals from alcohols and dioxolanes in mixed aqueous-organic solution though photoinduced hydrogen abstraction by disodium benzophenondisulfonate when exposed to solar light (6 to 14 hours for 10 g amounts). (Author) 8 refs.

The in vitro screening of aromatic amides as potential inhibitors of poly (ADP-ribose) polymerase

International Nuclear Information System (INIS)

Brown, D.M.; Horsman, M.R.; Lee, W.W.; Brown, J.M.

1984-01-01

It is now well established that the chromosomal enzyme poly (ADP-ribose) polymerase (ADPRP) is involved in the repair of DNA damage caused by ionizing radiation and alkylating agents, although the mechanisms involved are still not clear. ADPRP inhibitors include thymidine, nicotinamides, benzamides and methyl xanthines. The authors have demonstrated that these compounds are effective inhibitors of X-ray-induced potentially lethal damage repair (PLDR). More recently, they have shown that the cytotoxicity of the bifunctional alkylating L-phenylalanine mustard (L-PAM) was enhanced in vitro and in vivo by 3-aminobenzamide, nicotinamide and caffeine, although in the latter case pharmacokinetic changes could have contributed to the enhanced killing. The authors have examined a series of substituted carbocyclic and heterocyclic aromatic amides as potential inhibitors of ADPRP. The effect of these compounds on ADPRP activity in vitro as well as their effect on the repair of X-ray and alkylation damage in vitro are presented

Pi-activated alcohols: an emerging class of alkylating agents for catalytic Friedel-Crafts reactions.

Science.gov (United States)

Bandini, Marco; Tragni, Michele

2009-04-21

The direct functionalization of aromatic compounds, via Friedel-Crafts alkylation reactions with alcohols, is one of the cornerstones in organic chemistry. The present emerging area deals with the recent advances in the use of pi-activated alcohols in the catalytic and stereoselective construction of benzylic stereocenters.

Role of alkyl alcohol on viscosity of silica-based chemical gels for decontamination of highly radioactive nuclear facilities

International Nuclear Information System (INIS)

Choi, B. S.; Yoon, S. B.; Jung, C. H.; Lee, K. W.; Moon, J. K.

2012-01-01

Silica-based chemical gel for the decontamination of nuclear facilities was prepared by using fumed silica as a viscosifier, a 0.5 M Ce (IV) solution dissolved in concentrated nitric acid as a chemical decontamination agent, and tripropylene glycol butyl ether (TPGBE) as a co-viscosifier. A new effective strategy for the preparation of the chemical gel was investigated by introducing the alkyl alcohols as organic solvents to effectively dissolve the co-viscosifier. The mixture solution of the co-viscosifier and alkyl alcohols was more effective in the control of viscosity than that of the co-viscosifier only in gel. Here, the alkyl alcohols played a key role as an effective dissolution solvent for the co-viscosifier in the preparation of the chemical gel, resulting in a reducing of the amount of the co-viscosifier and gel time compared with that of the chemical gel prepared without the alkyl alcohols. It was considered that the alkyl alcohols contributed to the effective dissolution of the co-viscosifier as well as the homogeneous mixing in the formation of the gel, while the co-viscosifier in an aqueous media of the chemical decontamination agent solution showed a lower solubility. The decontamination efficiency of the chemical gels prepared in this work using a multi-channel analyzer (MCA) showed a high decontamination efficiency of over ca. 94% and ca. 92% for Co-60 and Cs-137 contaminated on surface of the stainless steel 304, respectively. (authors)

Chemistry of bifunctional photoprobes. 3 -- Correlation between the efficiency of CH insertion by photolabile chelating agents and lifetimes of singlet nitrenes by flash photolysis: First example of photochemical attachment of 99mTc-complex with human serum albumin

International Nuclear Information System (INIS)

Pandurangi, R.S.; Lusiak, P.; Kuntz, R.R.; Volkert, W.A.; Rogowski, J.; Platz, M.S.

1998-01-01

Systematic functionalization of perfluoroaryl azides with chelating agents capable of complexing transition metals produces a new class of bifunctional photolabile chelating agents (BFPCAs). The strategy is shield the azide functionality from the electronic and steric influence of the electron-rich metal Pd through ester and amide bridges raised CH insertion efficiency to unprecedented levels (>92%) in a model solvent (cyclohexane). In contrast, perfluoroaryl azides attached to chelating agents via hydrazones show no significant CH insertion in cyclohexane upon photolysis. Measurements of the lifetimes of the singlet nitrenes derived from these agents by flash photolysis techniques correlate well with the efficiency of CH insertion by demonstrating longer lifetimes (10--50 times) for singlet nitrenes derived from azidotetrafluorinated esters and amides compared with the related hydrazones, which failed to yield significant CH insertion. A representative BFPCA 12 is chelated to diagnostic radionuclide 99m Tc and covalently attached to human serum albumin via photochemical activation extending the favorable bimolecular insertion characteristics of BFPCA to tracer level concentrations in buffer conditions. Flash photolysis experiments correlate singlet nitrene lifetimes with the efficiency of intermolecular insertion reactions. This work provides new photo-cross-linking technology, useful in radiodiagnostics and radiotherapy in nuclear medicine

Synthesis, characterization and catalytic activity of acid-base bifunctional materials through protection of amino groups

Energy Technology Data Exchange (ETDEWEB)

Shao, Yanqiu [College of Chemistry, Jilin University, Changchun 130023 (China); College of Chemistry, Mudanjiang Normal University, Mudanjiang 157012 (China); Liu, Heng; Yu, Xiaofang [College of Chemistry, Jilin University, Changchun 130023 (China); Guan, Jingqi, E-mail: guanjq@jlu.edu.cn [College of Chemistry, Jilin University, Changchun 130023 (China); Kan, Qiubin, E-mail: qkan@mail.jlu.edu.cn [College of Chemistry, Jilin University, Changchun 130023 (China)

2012-03-15

Graphical abstract: Acid-base bifunctional mesoporous material SO{sub 3}H-SBA-15-NH{sub 2} was successfully synthesized under low acidic medium through protection of amino groups. Highlights: Black-Right-Pointing-Pointer The acid-base bifunctional material SO{sub 3}H-SBA-15-NH{sub 2} was successfully synthesized through protection of amino groups. Black-Right-Pointing-Pointer The obtained bifunctional material was tested for aldol condensation. Black-Right-Pointing-Pointer The SO{sub 3}H-SBA-15-NH{sub 2} catalyst containing amine and sulfonic acid groups exhibited excellent acid-basic properties. -- Abstract: Acid-base bifunctional mesoporous material SO{sub 3}H-SBA-15-NH{sub 2} was successfully synthesized under low acidic medium through protection of amino groups. X-ray diffraction (XRD), N{sub 2} adsorption-desorption, transmission electron micrographs (TEM), back titration, {sup 13}C magic-angle spinning (MAS) NMR and {sup 29}Si magic-angle spinning (MAS) NMR were employed to characterize the synthesized materials. The obtained bifunctional material was tested for aldol condensation reaction between acetone and 4-nitrobenzaldehyde. Compared with monofunctional catalysts of SO{sub 3}H-SBA-15 and SBA-15-NH{sub 2}, the bifunctional sample of SO{sub 3}H-SBA-15-NH{sub 2} containing amine and sulfonic acid groups exhibited excellent acid-basic properties, which make it possess high activity for the aldol condensation.

Poly(alkyl acrylate) nonparticles

International Nuclear Information System (INIS)

Kreuter, J.

1985-01-01

This study deals with the preparation of poly(alkyl acrylic) and poly(alkyl cyanocrylic) nanoparticles. Nonoparticles are solid colloidal particles, consisting of macromolecular materials in which drugs or biologically active materials are dissolved, entrapped, and encapsulated, and/or to which the active substance is adsorbed or attached. Poly(alkyl acrylic) nanoparticles are much more slowly biodegradable than poly(alkyl cyanoacrylate) nanoparticles, and are thus more suitable for drug delivery purposes. Poly(methyl methacrylate) is the material of choice for the use of nanoparticles as an adjuvant for vaccines and are produced by emulsifier-free polymerization in aqueous media. The polymerization, which can be initiated with gamma rays or with potassium peroxodisulfate, is described

The Mycobacterium tuberculosis Rv2540c DNA sequence encodes a bifunctional chorismate synthase

Directory of Open Access Journals (Sweden)

Santos Diógenes S

2008-04-01

Full Text Available Abstract Background The emergence of multi- and extensively-drug resistant Mycobacterium tuberculosis strains has created an urgent need for new agents to treat tuberculosis (TB. The enzymes of shikimate pathway are attractive targets to the development of antitubercular agents because it is essential for M. tuberculosis and is absent from humans. Chorismate synthase (CS is the seventh enzyme of this route and catalyzes the NADH- and FMN-dependent synthesis of chorismate, a precursor of aromatic amino acids, naphthoquinones, menaquinones, and mycobactins. Although the M. tuberculosis Rv2540c (aroF sequence has been annotated to encode a chorismate synthase, there has been no report on its correct assignment and functional characterization of its protein product. Results In the present work, we describe DNA amplification of aroF-encoded CS from M. tuberculosis (MtCS, molecular cloning, protein expression, and purification to homogeneity. N-terminal amino acid sequencing, mass spectrometry and gel filtration chromatography were employed to determine identity, subunit molecular weight and oligomeric state in solution of homogeneous recombinant MtCS. The bifunctionality of MtCS was determined by measurements of both chorismate synthase and NADH:FMN oxidoreductase activities. The flavin reductase activity was characterized, showing the existence of a complex between FMNox and MtCS. FMNox and NADH equilibrium binding was measured. Primary deuterium, solvent and multiple kinetic isotope effects are described and suggest distinct steps for hydride and proton transfers, with the former being more rate-limiting. Conclusion This is the first report showing that a bacterial CS is bifunctional. Primary deuterium kinetic isotope effects show that C4-proS hydrogen is being transferred during the reduction of FMNox by NADH and that hydride transfer contributes significantly to the rate-limiting step of FMN reduction reaction. Solvent kinetic isotope effects and

Lethal and mutagenic effects of radiation and alkylating agents on two strains of mouse L5178Y cells

International Nuclear Information System (INIS)

Evans, H.H.; Horng, M.; Beer, J.Z.

1986-01-01

The two closely related strains of L5178Y (LY) mouse lymphoma cells, LY-R and LY-S, have been shown to differ in their sensitivity to UV and ionizing radiation. In the present work, the lethal and mutagenic effects of ethyl methanesulfonate (EMS), methyl nitrosourea (MNU) and UV radiation (254 nm) were compared in the two strains. Mutability at the Na + /K + -ATPase locus as well as the HGPRT locus was determined. The authors found strain LY-S to be more resistant than strain LY-R to the lethal effects of UV radiation. In contrast, strain LY-S was more sensitive to the cytotoxic effects of the two alkylating agents. In spite of these differences in sensitivity, the authors found strain LY-S to be less mutable than strain LY-R by all 3 agents at the HGPRT locus. At the Na + /K + -ATPase locus, strain LY-S was also less mutable than strain LY-R by equal concentrations of EMS and UV radiation and by equitoxic concentrations of MNU. However, the difference between the strains was much more pronounced at the HGPRT locus than at the Na + /K + -ATPase locus. The authors have suggested that the interaction of unrepaired lesions in strain LY-S tends to cause an excess of deletions and multilocus effects, which in turn result in a locus-dependent decrease in the recovery of viable LY-S mutant cells. (Auth.)

Sensitization of melanoma cells to alkylating agent-induced DNA damage and cell death via orchestrating oxidative stress and IKKβ inhibition

Directory of Open Access Journals (Sweden)

Anfernee Kai-Wing Tse

2017-04-01

Full Text Available Nitrosourea represents one of the most active classes of chemotherapeutic alkylating agents for metastatic melanoma. Treatment with nitrosoureas caused severe systemic side effects which hamper its clinical use. Here, we provide pharmacological evidence that reactive oxygen species (ROS induction and IKKβ inhibition cooperatively enhance nitrosourea-induced cytotoxicity in melanoma cells. We identified SC-514 as a ROS-inducing IKKβ inhibitor which enhanced the function of nitrosoureas. Elevated ROS level results in increased DNA crosslink efficiency triggered by nitrosoureas and IKKβ inhibition enhances DNA damage signals and sensitizes nitrosourea-induced cell death. Using xenograft mouse model, we confirm that ROS-inducing IKKβ inhibitor cooperates with nitrosourea to reduce tumor size and malignancy in vivo. Taken together, our results illustrate a new direction in nitrosourea treatment, and reveal that the combination of ROS-inducing IKKβ inhibitors with nitrosoureas can be potentially exploited for melanoma therapy.

[The biochemical mechanisms of the action of N-alkyl-N-nitrosoureas. The possible reasons for drug resistance to these compounds].

Science.gov (United States)

Syrkin, A B; Gorbacheva, L B

1996-01-01

N-alkyl-N-nitrosoureas exhibit a wide spectrum of antitumor activity. They react as alkylating agents at nucleophilic sites in purine and pyrimidine moieties of DNA. The predominant site of this alkylation is N7 of guanine, which is followed by the site N3 of adenine and 06 of guanine. The formation and persistence of 0(6)-alkylguanine (0(6)-AG) may be of primary importance in cytotoxicity of the nitrosoureas. 0(6)-AG adducts of DNA of the tumor cells are repaired by protein 0(6)-alkylguanine-DNA transferase (0(6)-AGT) which transfers the alkyl group to internal cysteine residue being the acceptor protein for the alkyl group in an irreversible transfer reaction. 0(6)-AGT can protect the tumor cells against 0(6)-AG adducts by the way of inhibiting the formation of the DNA interstrand cross-links 0(6)-AGT plays an important role in the drug resistance because it repairs the DNA alkyl adducts at the 0(6) position of guanine. The 0(6)-AGT activity inversely correlates with the cytotoxic effect of the nitrosoureas. The agents like 0(6)-methylguanosine, 0(6)-methyl-2'-deoxyguanosine, and some 0(6)-benzylated guanine derivatives are effective inactivators of 0(6)-AGT, and thus can be used to enhance the cytotoxicity of N-nitrosoureas. The activation of 0(6)-AGT and other repairing enzymes such as alpha and beta DNA-polymerases as well as an increase in the level of reduced glutathione may be used in developing the resistance to the nitrosoureas.

Ada response – a strategy for repair of alkylated DNA in bacteria

Science.gov (United States)

Mielecki, Damian; Grzesiuk, Elżbieta

2014-01-01

Alkylating agents are widespread in the environment and also occur endogenously. They can be cytotoxic or mutagenic to the cells introducing alkylated bases to DNA or RNA. All organisms have evolved multiple DNA repair mechanisms to counteract the effects of DNA alkylation: the most cytotoxic lesion, N3-methyladenine (3meA), is excised by AlkA glycosylase initiating base excision repair (BER); toxic N1-methyladenine (1meA) and N3-methylcytosine (3meC), induced in DNA and RNA, are removed by AlkB dioxygenase; and mutagenic and cytotoxic O6-methylguanine (O6meG) is repaired by Ada methyltransferase. In Escherichia coli, Ada response involves the expression of four genes, ada, alkA, alkB, and aidB, encoding respective proteins Ada, AlkA, AlkB, and AidB. The Ada response is conserved among many bacterial species; however, it can be organized differently, with diverse substrate specificity of the particular proteins. Here, an overview of the organization of the Ada regulon and function of individual proteins is presented. We put special effort into the characterization of AlkB dioxygenases, their substrate specificity, and function in the repair of alkylation lesions in DNA/RNA. PMID:24810496

Ada response - a strategy for repair of alkylated DNA in bacteria.

Science.gov (United States)

Mielecki, Damian; Grzesiuk, Elżbieta

2014-06-01

Alkylating agents are widespread in the environment and also occur endogenously. They can be cytotoxic or mutagenic to the cells introducing alkylated bases to DNA or RNA. All organisms have evolved multiple DNA repair mechanisms to counteract the effects of DNA alkylation: the most cytotoxic lesion, N(3)-methyladenine (3meA), is excised by AlkA glycosylase initiating base excision repair (BER); toxic N(1)-methyladenine (1meA) and N(3)-methylcytosine (3meC), induced in DNA and RNA, are removed by AlkB dioxygenase; and mutagenic and cytotoxic O(6)-methylguanine (O(6) meG) is repaired by Ada methyltransferase. In Escherichia coli, Ada response involves the expression of four genes, ada, alkA, alkB, and aidB, encoding respective proteins Ada, AlkA, AlkB, and AidB. The Ada response is conserved among many bacterial species; however, it can be organized differently, with diverse substrate specificity of the particular proteins. Here, an overview of the organization of the Ada regulon and function of individual proteins is presented. We put special effort into the characterization of AlkB dioxygenases, their substrate specificity, and function in the repair of alkylation lesions in DNA/RNA. © 2014 The Authors. FEMS Microbiology Letters published by John Wiley & Sons Ltd on behalf of Federation of European Microbiological Societies.

Process for recovering uranium using an alkyl pyrophosphoric acid and alkaline stripping solution

International Nuclear Information System (INIS)

Worthington, R.E.; Magdics, A.

1987-01-01

A process is described for stripping uranium for a pregnant organic extractant comprising an alkyl pyrophosphoric acid dissolved in a substantially water-immiscible organic diluent. The organic extractant contains tetravalent uranium and an alcohol or phenol modifier in a quantity sufficient to retain substantially all the unhydrolyzed alkyl pyrophosphoric acid in solution in the diluent during stripping. The process comprises adding an oxidizing agent to the organic extractant and thereby oxidizing the tetravalent uranium to the +6 state in the organic extractant, and contacting the organic extractant containing the uranium in the +6 state with a stripping solution comprising an aqueous solution of an alkali metal or ammonium carbonate or hydroxide thereby stripping uranium from the organic extractant into the stripping solution. The resulting barren organic extractant containing substantially all of the unhydrolyzed alkyl pyrophosphoric acid dissolved in the diluent is separated from the stripping solution containing the stripped uranium, the barren extractant being suitable for recycle

Outlook for the U.S. alkylation industry

International Nuclear Information System (INIS)

Felten, J.R.; Bradshaw, T.; McCarthy, K.

1994-01-01

Alkylation has long been recognized in the refining industry as one of the best options to convert refinery olefins into valuable, clean, high octane blending components. In fact, refinery alkylation is a preferred source of blending stocks for reformulated gasoline. However, the hydrofluoric acid (HF) alkylation process and, to a lesser extent, the sulfuric acid (SA) process have come under increasing pressure in the US due to safety and environmental concerns. This paper examines the current outlook for the US alkylation industry including: key trends and driving forces in the industry, the impact of environmental issues on both HF and SA alkylation, US alkylation supply/demand forecast including the outlook for oxygenates, how US refines will respond to the increased demand and restricted supply for alkylates, and the outlook for new solid acid alkylation (SAC) technology

Hyperthermia and chemotherapy agent

International Nuclear Information System (INIS)

Roizin-Towle, L.; Hall, E.J.

1981-01-01

The use of chemotherapeutic agents for the treatment of cancer dates back to the late 19th century, but the modern era of chemotherapy drugs was ushered in during the 1940's with the development of the polyfunctional alkylating agent. Since then, numerous classes of drugs have evolved and the combined use of antineoplastic agents with other treatment modalities such as radiation or heat, remains a large relatively unexplored area. This approach, combining local hyperthermia with chemotherapy agents affords a measure of targeting and selective toxicity not previously available for drugs. In this paper, the effects of adriamycin, bleomycin and cis-platinum are examined. The adjuvant use of heat may also reverse the resistance of hypoxic cells noted for some chemotherapy agents

DNA-Directed alkylating agents. 7. Synthesis, DNA interaction, and antitumor activity of bis(hydroxymethyl)- and bis(carbamate)-substituted pyrrolizines and imidazoles.

Science.gov (United States)

Atwell, G J; Fan, J Y; Tan, K; Denny, W A

1998-11-19

A series of bis(hydroxymethyl)-substituted imidazoles, thioimidazoles, and pyrrolizines and related bis(carbamates), linked to either 9-anilinoacridine (intercalating) or 4-(4-quinolinylamino)benzamide (minor groove binding) carriers, were synthesized and evaluated for sequence-specific DNA alkylation and cytotoxicity. The imidazole and thioimidazole analogues were prepared by initial synthesis of [(4-aminophenyl)alkyl]imidazole-, thioimidazole-, or pyrrolizine dicarboxylates, coupling of these with the desired carrier, and reduction to give the required bis(hydroxymethyl) alkylating moiety. The pyrrolizines were the most reactive alkylators, followed by the thioimidazoles, while the imidazoles were unreactive. The pyrrolizines and some of the thioimidazoles cross-linked DNA, as measured by agarose gel electrophoresis. Strand cleavage assays showed that none of the compounds reacted at purine N7 or N3 sites in the gpt region of the plasmid gpt2Eco, but the polymerase stop assay showed patterns of G-alkylation in C-rich regions. The corresponding thioimidazole bis(carbamates) were more selective than the bis(hydroxymethyl) pyrrolizines, with high-intensity bands at 5'-NCCN, 5'-NGCN and 5'-NCGN sequences in the PCR stopping assay ( indicates block sites). The data suggest that these targeted compounds, like the known thioimidazole bis(carbamate) carmethizole, alkylate exclusively at guanine residues via the 2-amino group, with little or no alkylation at N3 and N7 guanine or adenine sites. The cytotoxicities of the compounds correlated broadly with their reactivities, with the bis(hydroxymethyl)imidazoles being the least cytotoxic (IC50s >1 microM; P388 leukemia) and with the intercalator-linked analogues being more cytotoxic than the corresponding minor-groove-targeted ones. This was true also for the more reactive thioimidazole bis(carbamates) (IC50s 0.8 and 11 microM, respectively), but both were more active than the analogous "untargeted" carmethizole (IC50 20

Immunological detection of O6-methylguanine in alkylated DNA

International Nuclear Information System (INIS)

Briscoe, W.T.; Spizizen, J.; Tan, E.M.

1978-01-01

Antibodies to O 6 -methyldeoxyguanosine were produced in rabbits and utilized in a radioimmunoassay to detect this nucleoside at picomole levels. The specificity of the antibodies was demonstrated by the use of nucleoside analogues as inhibitors in the radioimmunoassay. The antibodies cross-reacted with O 6 -methylguanosine, O 6 -methylguanine, and O 6 -ethylguanosine. There was 10 4 to 10 6 times less sensitivity to inhibition by deoxyadenosine, deoxyguanosine, and guanosine than by O 6 -methyldeoxyguanosine. The radioimmunoassay also detected O 6 -methylguanine in DNA alkylated by agents known to produce O 6 -methylguanine, such as N'-methyl-N-nitrosourea. DNA alkylated with dimethyl sulfate, which does not produce O 6 -methylguanine in DNA, cross-reacted with the antibodies to a very limited extent. Such an assay system for modified nucleic acid components would be very useful in following the production, persistence, and repair of these lesions in a variety of cells and tissues treated with a broad spectrum of carcinogens and suspected carcinogens

Distributed Drug Discovery, Part 2: Global Rehearsal of Alkylating Agents for the Synthesis of Resin-Bound Unnatural Amino Acids and Virtual D3 Catalog Construction

Science.gov (United States)

2008-01-01

Distributed Drug Discovery (D3) proposes solving large drug discovery problems by breaking them into smaller units for processing at multiple sites. A key component of the synthetic and computational stages of D3 is the global rehearsal of prospective reagents and their subsequent use in the creation of virtual catalogs of molecules accessible by simple, inexpensive combinatorial chemistry. The first section of this article documents the feasibility of the synthetic component of Distributed Drug Discovery. Twenty-four alkylating agents were rehearsed in the United States, Poland, Russia, and Spain, for their utility in the synthesis of resin-bound unnatural amino acids 1, key intermediates in many combinatorial chemistry procedures. This global reagent rehearsal, coupled to virtual library generation, increases the likelihood that any member of that virtual library can be made. It facilitates the realistic integration of worldwide virtual D3 catalog computational analysis with synthesis. The second part of this article describes the creation of the first virtual D3 catalog. It reports the enumeration of 24 416 acylated unnatural amino acids 5, assembled from lists of either rehearsed or well-precedented alkylating and acylating reagents, and describes how the resulting catalog can be freely accessed, searched, and downloaded by the scientific community. PMID:19105725

Sensitization of melanoma cells to alkylating agent-induced DNA damage and cell death via orchestrating oxidative stress and IKKβ inhibition.

Science.gov (United States)

Tse, Anfernee Kai-Wing; Chen, Ying-Jie; Fu, Xiu-Qiong; Su, Tao; Li, Ting; Guo, Hui; Zhu, Pei-Li; Kwan, Hiu-Yee; Cheng, Brian Chi-Yan; Cao, Hui-Hui; Lee, Sally Kin-Wah; Fong, Wang-Fun; Yu, Zhi-Ling

2017-04-01

Nitrosourea represents one of the most active classes of chemotherapeutic alkylating agents for metastatic melanoma. Treatment with nitrosoureas caused severe systemic side effects which hamper its clinical use. Here, we provide pharmacological evidence that reactive oxygen species (ROS) induction and IKKβ inhibition cooperatively enhance nitrosourea-induced cytotoxicity in melanoma cells. We identified SC-514 as a ROS-inducing IKKβ inhibitor which enhanced the function of nitrosoureas. Elevated ROS level results in increased DNA crosslink efficiency triggered by nitrosoureas and IKKβ inhibition enhances DNA damage signals and sensitizes nitrosourea-induced cell death. Using xenograft mouse model, we confirm that ROS-inducing IKKβ inhibitor cooperates with nitrosourea to reduce tumor size and malignancy in vivo. Taken together, our results illustrate a new direction in nitrosourea treatment, and reveal that the combination of ROS-inducing IKKβ inhibitors with nitrosoureas can be potentially exploited for melanoma therapy. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

"Click" chemistry mildly stabilizes bifunctional gold nanoparticles for sensing and catalysis.

Science.gov (United States)

Li, Na; Zhao, Pengxiang; Liu, Na; Echeverria, María; Moya, Sergio; Salmon, Lionel; Ruiz, Jaime; Astruc, Didier

2014-07-01

A large family of bifunctional 1,2,3-triazole derivatives that contain both a polyethylene glycol (PEG) chain and another functional fragment (e.g., a polymer, dendron, alcohol, carboxylic acid, allyl, fluorescence dye, redox-robust metal complex, or a β-cyclodextrin unit) has been synthesized by facile "click" chemistry and mildly coordinated to nanogold particles, thus providing stable water-soluble gold nanoparticles (AuNPs) in the size range 3.0-11.2 nm with various properties and applications. In particular, the sensing properties of these AuNPs are illustrated through the detection of an analogue of a warfare agent (i.e., sulfur mustard) by means of a fluorescence "turn-on" assay, and the catalytic activity of the smallest triazole-AuNPs (core of 3.0 nm) is excellent for the reduction of 4-nitrophenol in water. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Glioma cell death induced by irradiation or alkylating agent chemotherapy is independent of the intrinsic ceramide pathway.

Directory of Open Access Journals (Sweden)

Dorothee Gramatzki

Full Text Available Resistance to genotoxic therapy is a characteristic feature of glioma cells. Acid sphingomyelinase (ASM hydrolyzes sphingomyelin to ceramide and glucosylceramide synthase (GCS catalyzes ceramide metabolism. Increased ceramide levels have been suggested to enhance chemotherapy-induced death of cancer cells.Microarray and clinical data for ASM and GCS in astrocytomas WHO grade II-IV were acquired from the Rembrandt database. Moreover, the glioblastoma database of the Cancer Genome Atlas network (TCGA was used for survival data of glioblastoma patients. For in vitro studies, increases in ceramide levels were achieved either by ASM overexpression or by the GCS inhibitor DL-threo-1-phenyl-2-palmitoylamino-3-morpholino-1-propanol (PPMP in human glioma cell lines. Combinations of alkylating chemotherapy or irradiation and ASM overexpression, PPMP or exogenous ceramide were applied in parental cells. The anti-glioma effects were investigated by assessing proliferation, metabolic activity, viability and clonogenicity. Finally, viability and clonogenicity were assessed in temozolomide (TMZ-resistant cells upon treatment with PPMP, exogenous ceramide, alkylating chemotherapy, irradiation or their combinations.Interrogations from the Rembrandt and TCGA database showed a better survival of glioblastoma patients with low expression of ASM or GCS. ASM overexpression or PPMP treatment alone led to ceramide accumulation but did not enhance the anti-glioma activity of alkylating chemotherapy or irradiation. PPMP or exogenous ceramide induced acute cytotoxicity in glioblastoma cells. Combined treatments with chemotherapy or irradiation led to additive, but not synergistic effects. Finally, no synergy was found when TMZ-resistant cells were treated with exogenous ceramide or PPMP alone or in combination with TMZ or irradiation.Modulation of intrinsic glioma cell ceramide levels by ASM overexpression or GCS inhibition does not enhance the anti-glioma activity of

Synthesis of deuterium-labeled analogs of the lipid hydroperoxide-derived bifunctional electrophile 4-oxo-2(E)-nonenal

OpenAIRE

Arora, Jasbir S.; Oe, Tomoyuki; Blair, Ian A.

2011-01-01

Lipid hydroperoxides undergo homolytic decomposition into the bifunctional 4-hydroxy-2(E)-nonenal and 4-oxo-2(E)-nonenal (ONE). These bifunctional electrophiles are highly reactive and can readily modify intracellular molecules including glutathione (GSH), deoxyribonucleic acid (DNA) and proteins. Lipid hydroperoxide-derived bifunctional electrophiles are thought to contribute to the pathogenesis of a number of diseases. ONE is an α,β-unsaturated aldehyde that can react in multiple ways and w...

Graft copolymerization of a series of alkyl acrylates and alkyl methacrylates onto polyethylene

International Nuclear Information System (INIS)

Zurakowska-Orszagh, J.; Soerjosoeharto, K.; Busz, W.; Oldziejewski, J.

1977-01-01

Graft copolymerization of a series of alkyl acrylates and alkyl methacrylates into polyethylene of Polish production was investigated, using benzoyl peroxide as the initiator as well as preirradiation technique, namely ionizing radiation from a 60 Co γ-source. The effect of α-carbon methyl substituent of methacrylates as well as the influence of the length of alkyl chains in the ester groups of both series of monomers into the grafting process was observed. The ungrafted and some of the grafted polyethylene film obtained was studied by infrared spectrophotometry. (author)

[Genetic aspects of the action of immunosuppressive agents].

Science.gov (United States)

Pevnitskiĭ, L A; Pisarev, V M; Telegin, L Iu; Tutel'ian, A V

1992-01-01

The data were obtained formerly that mice of certain strains essentially differ in the sensitivity to the immunodepressive and antiproliferative action of the alkylating agents (so-called opposite strains: DBA/2--highly sensitive, BALB/c--resistant). It is shown in the present work that with the use of the other non-alkylating immunodepressive agents (cytarabine, cyclosporin A, dexamethasone) that differ in the action mode, DBA/2 mice retain a high sensitivity whereas BALB/c mice a low sensitivity to all the immunodepressants. The sensitivity to the immunodepressive action in vivo directly correlates with that of the immunocompetent cells in vitro. Potential mechanisms determining the same type sensitivity to diverse immunodepressant in mice belonging to the above-indicated genotypes are under discussion.

Sensitization of gastric cancer cells to alkylating agents by glaucocalyxin B via cell cycle arrest and enhanced cell death.

Science.gov (United States)

Ur Rahman, Muhammad Saif; Zhang, Ling; Wu, Lingyan; Xie, Yuqiong; Li, Chunchun; Cao, Jiang

2017-01-01

Severe side effects are major problems with chemotherapy of gastric cancer (GC). These side effects can be reduced by using sensitizing agents in combination with therapeutic drugs. In this study, the low/nontoxic dosage of glaucocalyxin B (GLB) was used with other DNA linker agents mitomycin C (MMC), cisplatin (DDP), or cyclophosphamide (CTX) to treat GC cells. Combined effectiveness of GLB with drugs was determined by proliferation assay. The molecular mechanisms associated with cell proliferation, migration, invasion, cell cycle, DNA repair/replication, apoptosis, and autophagy were investigated by immunoblotting for key proteins involved. Cell cycle and apoptosis analysis were performed by flow cytometry. Reactive oxygen species level was also examined for identification of its role in apoptosis. Proliferation assay revealed that the addition of 5 µM GLB significantly sensitizes gastric cancer SGC-7901 cells to MMC, DDP, and CTX by decreasing half-maximal inhibitory concentration (IC 50 ) by up to 75.40%±5%, 45.10%±5%, and 52.10%±5%, respectively. GLB + drugs decreased the expression level of proteins involved in proliferation and migration, suggesting the anticancer potential of GLB + drugs. GLB + MMC, GLB + CTX, and GLB + DDP arrest the cells in G 0 /G 1 and G 1 /S phase, respectively, which may be the consequence of significant decrease in the level of enzymes responsible for DNA replication and telomerase shortening. Combined use of GLB with these drugs also induces DNA damage and apoptosis by activating caspase/PARP pathways and increased production of reactive oxygen species and increased autophagy in GC cells. GLB dosage sensitizes GC cells to the alkylating agents via arresting the cell cycle and enhancing cell death. This is of significant therapeutic importance in the reduction of side effects associated with these drugs.

Photoinduced, copper-catalyzed alkylation of amides with unactivated secondary alkyl halides at room temperature.

Science.gov (United States)

Do, Hien-Quang; Bachman, Shoshana; Bissember, Alex C; Peters, Jonas C; Fu, Gregory C

2014-02-05

The development of a mild and general method for the alkylation of amides with relatively unreactive alkyl halides (i.e., poor substrates for SN2 reactions) is an ongoing challenge in organic synthesis. We describe herein a versatile transition-metal-catalyzed approach: in particular, a photoinduced, copper-catalyzed monoalkylation of primary amides. A broad array of alkyl and aryl amides (as well as a lactam and a 2-oxazolidinone) couple with unactivated secondary (and hindered primary) alkyl bromides and iodides using a single set of comparatively simple and mild conditions: inexpensive CuI as the catalyst, no separate added ligand, and C-N bond formation at room temperature. The method is compatible with a variety of functional groups, such as an olefin, a carbamate, a thiophene, and a pyridine, and it has been applied to the synthesis of an opioid receptor antagonist. A range of mechanistic observations, including reactivity and stereochemical studies, are consistent with a coupling pathway that includes photoexcitation of a copper-amidate complex, followed by electron transfer to form an alkyl radical.

Composition suitable as collection agent in ore flotation process and preparation of said composition

International Nuclear Information System (INIS)

Bresson, C.R.; Parlman, R.M.

1984-01-01

A composition and process are provided for the recovery of the values of zinc, molybdenum, copper, lead, ion (pyrite), and iron-containing small amounts of gold or uranium, or both, from ores comprising these mineral sulfides. The aqueous composition is the impure form of an alkali metal alkyl trithiocarbonate compound. The process comprises employing said aqueous composition as a collection agent for the above minerals in an ore recovery process. A process for the separation of zinc values from lead values from an ore comprising both is provided by employing an alkali metal alkyl trithiocarbonate compound as a collection agent for zinc. In addition, both a composition and process are provided for the recovery of the values of iron, copper, and lead from ores comprising these values. The composition consists essentially of a dispersant and an impure form of an alkali metal alkyl trithiocarbonate compound. The process comprises employing this composition as a collection agent for the above minerals in an ore recovery process

Synthesis of acid-base bifunctional mesoporous materials by oxidation and thermolysis

Energy Technology Data Exchange (ETDEWEB)

Yu, Xiaofang [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China); Zou, Yongcun [State Key Laboratory of Inoranic Synthesis and Preparative Chemistryg, College of Chemistry, Jilin University, Changchun 130012 (China); Wu, Shujie; Liu, Heng [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China); Guan, Jingqi, E-mail: guanjq@jlu.edu.cn [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China); Kan, Qiubin, E-mail: qkan@jlu.edu.cn [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China)

2011-06-15

Graphical abstract: A novel and efficient method has been developed for the synthesis of acid-base bifunctional catalyst. The obtained sample of SO{sub 3}H-MCM-41-NH{sub 2} containing amine and sulfonic acids exhibits excellent catalytic activity in aldol condensation reaction. Research highlights: {yields} Synthesize acid-base bifunctional mesoporous materials SO{sub 3}H-MCM-41-NH{sub 2}. {yields} Oxidation and then thermolysis to generate acidic site and basic site. {yields} Exhibit good catalytic performance in aldol condensation reaction between acetone and various aldehydes. -- Abstract: A novel and efficient method has been developed for the synthesis of acid-base bifunctional catalyst SO{sub 3}H-MCM-41-NH{sub 2}. This method was achieved by co-condensation of tetraethylorthosilicate (TEOS), 3-mercaptopropyltrimethoxysilane (MPTMS) and (3-triethoxysilylpropyl) carbamicacid-1-methylcyclohexylester (3TAME) in the presence of cetyltrimethylammonium bromide (CTAB), followed by oxidation and then thermolysis to generate acidic site and basic site. X-ray diffraction (XRD) and transmission electron micrographs (TEM) show that the resultant materials keep mesoporous structure. Thermogravimetric analysis (TGA), X-ray photoelectron spectra (XPS), back titration, solid-state {sup 13}C CP/MAS NMR and solid-state {sup 29}Si MAS NMR confirm that the organosiloxanes were condensed as a part of the silica framework. The bifunctional sample (SO{sub 3}H-MCM-41-NH{sub 2}) containing amine and sulfonic acids exhibits excellent acid-basic properties, which make it possess high activity in aldol condensation reaction between acetone and various aldehydes.

Câncer e agentes antineoplásicos ciclo-celular específicos e ciclo-celular não específicos que interagem com o DNA: uma introdução Cancer and cell cicle-specific and cell cicle nonspecific anticancer DNA-interactive agents: an introduction

Directory of Open Access Journals (Sweden)

Vera Lúcia de Almeida

2005-02-01

Full Text Available The chemotherapy agents against cancer may be classified as "cell cycle-specific" or "cell cycle-nonspecific". Nevertheless, several of them have their biological activity related to any kind of action on DNA such as: antimetabolic agents (DNA synthesis inhibition, inherently reactive agents (DNA alkylating electrophilic traps for macromolecular nucleophiles from DNA through inter-strand cross-linking - ISC - alkylation and intercalating agents (drug-DNA interactions inherent to the binding made due to the agent penetration in to the minor groove of the double helix. The earliest and perhaps most extensively studied and most heavily employed clinical anticancer agents in use today are the DNA inter-strand cross-linking agents.

Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons

Science.gov (United States)

Zecevic, Jovana; Vanbutsele, Gina; de Jong, Krijn P.; Martens, Johan A.

2015-12-01

The ability to control nanoscale features precisely is increasingly being exploited to develop and improve monofunctional catalysts. Striking effects might also be expected in the case of bifunctional catalysts, which are important in the hydrocracking of fossil and renewable hydrocarbon sources to provide high-quality diesel fuel. Such bifunctional hydrocracking catalysts contain metal sites and acid sites, and for more than 50 years the so-called intimacy criterion has dictated the maximum distance between the two types of site, beyond which catalytic activity decreases. A lack of synthesis and material-characterization methods with nanometre precision has long prevented in-depth exploration of the intimacy criterion, which has often been interpreted simply as ‘the closer the better’ for positioning metal and acid sites. Here we show for a bifunctional catalyst—comprising an intimate mixture of zeolite Y and alumina binder, and with platinum metal controllably deposited on either the zeolite or the binder—that closest proximity between metal and zeolite acid sites can be detrimental. Specifically, the selectivity when cracking large hydrocarbon feedstock molecules for high-quality diesel production is optimized with the catalyst that contains platinum on the binder, that is, with a nanoscale rather than closest intimacy of the metal and acid sites. Thus, cracking of the large and complex hydrocarbon molecules that are typically derived from alternative sources, such as gas-to-liquid technology, vegetable oil or algal oil, should benefit especially from bifunctional catalysts that avoid locating platinum on the zeolite (the traditionally assumed optimal location). More generally, we anticipate that the ability demonstrated here to spatially organize different active sites at the nanoscale will benefit the further development and optimization of the emerging generation of multifunctional catalysts.

40 CFR 721.9892 - Alkylated urea.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkylated urea. 721.9892 Section 721... Alkylated urea. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as an alkylated urea (PMN P-93-1649) is subject to reporting under this...

Identify alkylation hazards

International Nuclear Information System (INIS)

Scott, B.

1992-01-01

This paper reports that extensive experience shows that alkylation plants regardless of acid catalyst choice, can be operated safely, and with minimum process risk to employees or neighbors. Both types of plants require a comprehensive and fully supported hazard management program that accounts for differing physical properties of the acids involved. Control and mitigation cost to refiners will vary considerably from plant to plant and location to location. In the author's experience, the order of magnitude costs will be about $1 to $2 million for a sulfuric acid (SA) alkylation plant, and about $10 to $15 million for a hydrofluoric acid (HF) plant. These costs include water supply systems and impoundment facilities for contaminated runoff water. The alkylation process, which chemically reacts isobutane and light olefins in the presence of a strong acid catalyst into a premium gasoline component is described

Investigation of J-shaped dose-responses induced by exposure to the alkylating agent N-methyl-N-nitrosourea.

Science.gov (United States)

Chapman, Katherine E; Hoffmann, George R; Doak, Shareen H; Jenkins, Gareth J S

2017-07-01

Hormesis is defined as a biphasic dose-response where biological effects of low doses of a stressor demonstrate the opposite effect to high-dose effects of the same stressor. Hormetic, or J-shaped, dose-response relationships are relatively rarely observed in toxicology, resulting in a limited understanding and even some skepticism of the concept. Low dose-response studies for genotoxicity endpoints have been performed at Swansea University for over a decade. However, no statistically significant decreases below control genotoxicity levels have been detected until recently. A hormetic-style dose-response following a 24h exposure to the alkylating agent N-methyl-N-nitrosourea (MNU) was observed in a previous study for HPRT mutagenesis in the human lymphoblastoid cell line AHH-1. A second recent study demonstrated a J-shaped dose-response for the induction of micronuclei by MNU in a 24h treatment in a similar test system. Following mechanistic investigations, it was hypothesized that p53 may be responsible for the observed hormetic phenomenon. As genotoxic carcinogens are a major causative factor of many cancers, consideration of hormesis in carcinogenesis could be important in safety assessment. The data examined here offer possible insights into hormesis, including its estimated prevalence, underlying mechanisms and lack of generalizability. Copyright © 2017 Elsevier B.V. All rights reserved.

The DinB•RecA complex of Escherichia coli mediates an efficient and high-fidelity response to ubiquitous alkylation lesions.

Science.gov (United States)

Cafarelli, Tiziana M; Rands, Thomas J; Godoy, Veronica G

2014-03-01

Alkylation DNA lesions are ubiquitous, and result from normal cellular metabolism as well as from treatment with methylating agents and chemotherapeutics. DNA damage tolerance by translesion synthesis DNA polymerases has an important role in cellular resistance to alkylating agents. However, it is not yet known whether Escherichia coli (E. coli) DNA Pol IV (DinB) alkylation lesion bypass efficiency and fidelity in vitro are similar to those inferred by genetic analyses. We hypothesized that DinB-mediated bypass of 3-deaza-3-methyladenine, a stable analog of 3-methyladenine, the primary replication fork-stalling alkylation lesion, would be of high fidelity. We performed here the first kinetic analyses of E. coli DinB•RecA binary complexes. Whether alone or in a binary complex, DinB inserted the correct deoxyribonucleoside triphosphate (dNTP) opposite either lesion-containing or undamaged template; the incorporation of other dNTPs was largely inefficient. DinB prefers undamaged DNA, but the DinB•RecA binary complex increases its catalytic efficiency on lesion-containing template, perhaps as part of a regulatory mechanism to better respond to alkylation damage. Notably, we find that a DinB derivative with enhanced affinity for RecA, either alone or in a binary complex, is less efficient and has a lower fidelity than DinB or DinB•RecA. This finding contrasts our previous genetic analyses. Therefore, mutagenesis resulting from alkylation lesions is likely limited in cells by the activity of DinB•RecA. These two highly conserved proteins play an important role in maintaining genomic stability when cells are faced with ubiquitous DNA damage. Kinetic analyses are important to gain insights into the mechanism(s) regulating TLS DNA polymerases. Copyright © 2013 Wiley Periodicals, Inc.

Inhibition of thioredoxin reductase but not of glutathione reductase by the major classes of alkylating and platinum-containing anticancer compounds.

Science.gov (United States)

Witte, Anne-Barbara; Anestål, Karin; Jerremalm, Elin; Ehrsson, Hans; Arnér, Elias S J

2005-09-01

Mammalian thioredoxin reductase (TrxR) is important for cell proliferation, antioxidant defense, and redox signaling. Together with glutathione reductase (GR) it is the main enzyme providing reducing equivalents to many cellular processes. GR and TrxR are flavoproteins of the same enzyme family, but only the latter is a selenoprotein. With the active site containing selenocysteine, TrxR may catalyze reduction of a wide range of substrates, but can at the same time easily be targeted by electrophilic compounds due to the extraordinarily high reactivity of a selenolate moiety. Here we addressed the inhibition of the enzyme by major anticancer alkylating agents and platinum-containing compounds and we compared it to that of GR. We confirmed prior studies suggesting that the nitrosourea carmustine can inhibit both GR and TrxR. We next found, however, that nitrogen mustards (chlorambucil and melphalan) and alkyl sulfonates (busulfan) efficiently inhibited TrxR while these compounds, surprisingly, did not inhibit GR. Inhibitions were concentration and time dependent and apparently irreversible. Anticancer anthracyclines (daunorubicin and doxorubicin) were, in contrast to the alkylating agents, not inhibitors but poor substrates of TrxR. We also found that TrxR, but not GR, was efficiently inhibited by both cisplatin, its monohydrated complex, and oxaliplatin. Carboplatin, in contrast, could not inhibit any of the two enzymes. These findings lead us to conclude that representative compounds of the major classes of clinically used anticancer alkylating agents and most platinum compounds may easily target TrxR, but not GR. The TrxR inhibition should thereby be considered as a factor that may contribute to the cytotoxicity seen upon clinical use of these drugs.

Effect of Anti-Parasite Chemotherapeutic Agents on Immune Reactions.

Science.gov (United States)

1980-08-01

observations). Similar effects of a number of other alkylating agents have been noticed (9, and personal observa- tions). Similarly, corticosteroids inhibit...Wellham, L. L., and Sigel, M. M. Ef- fect of anti-cancer chemotherapeutic agents on immune reactions of mice. I. Comparison of two nitrosoureas . J...7 D-Ri138 852 EFFECT OF ANTI-PARASITE CHEMOTHERAPEUTIC AGENTS ON i/i IMMUNE REACTIONS(U) SOUTH CAROLINA UNIV COLUMBIA DEPT OF MICROBIOLOGY AND

Chain length effects on the vibrational structure and molecular interactions in the liquid normal alkyl alcohols

Science.gov (United States)

Kiefer, Johannes; Wagenfeld, Sabine; Kerlé, Daniela

2018-01-01

Alkyl alcohols are widely used in academia, industry, and our everyday lives, e.g. as cleaning agents and solvents. Vibrational spectroscopy is commonly used to identify and quantify these compounds, but also to study their structure and behavior. However, a comprehensive investigation and comparison of all normal alkanols that are liquid at room temperature has not been performed, surprisingly. This study aims at bridging this gap with a combined experimental and computational effort. For this purpose, the alkyl alcohols from methanol to undecan-1-ol have been analyzed using infrared and Raman spectroscopy. A detailed assignment of the individual peaks is presented and the influence of the alkyl chain length on the hydrogen bonding network is discussed. A 2D vibrational mapping allows a straightforward visualization of the effects. The conclusions drawn from the experimental data are backed up with results from Monte Carlo simulations using the simulation package Cassandra.

Removing polysaccharides-and saccharides-related coloring impurities in alkyl polyglycosides by bleaching with the H2O2/TAED/NaHCO3 system.

Science.gov (United States)

Yanmei, Liu; Jinliang, Tao; Jiao, Sun; Wenyi, Chen

2014-11-04

The effect of H2O2/TAED/NaHCO3 system, namely NaHCO3 as alkaline agent with the (tetra acetyl ethylene diamine (TAED)) TAED-activated peroxide system, bleaching of alkyl polyglycosides solution was studied by spectrophotometry. The results showed that the optimal bleaching conditions about H2O2/TAED/NaHCO3 system bleaching of alkyl polyglycosides solution were as follows: molar ratio of TAED to H2O2 was 0.06, addition of H2O2 was 8.6%, addition of NaHCO3 was 3.2%, bleaching temperature of 50-65 °C, addition of MgO was 0.13%, and bleaching time was 8h. If too much amount of NaHCO3 was added to the system and maintained alkaline pH, the bleaching effect would be greatly reduced. Fixing molar ratio of TAED to H2O2 and increasing the amount of H2O2 were beneficial to improve the whiteness of alkyl polyglycosides, but adding too much amount of H2O2 would reduce the transparency. In the TAED-activated peroxide system, NaHCO3 as alkaline agent and buffer agent, could overcome the disadvantage of producing black precipitates when NaOH as alkaline agent. Copyright © 2014 Elsevier Ltd. All rights reserved.

Alkylation of reticular polymers of ethynyl piperidol by alkyl halogen and investigation of the swelling of the products in water

International Nuclear Information System (INIS)

Khakimkhodjaev, S.N.; Khalikov, D.Kh.

1999-01-01

In the paper the results of investigation on alkylation of reticular polymer of ethyl piperidol by methyl Iodide and ethyl Iodide are adduced. It have been shown that in the first case the reaction of an alkylation proceeds up to 100% of a degree of completion. In the second case of an alkylation the highest degree of alkylation reaches only 60% which is connected with formation of secondary structures. In both cases the process of an alkylation results in deriving highly swelled system

Long alkyl-chain imidazolium ionic liquids: Antibiofilm activity against phototrophic biofilms.

Science.gov (United States)

Reddy, G Kiran Kumar; Nancharaiah, Y V; Venugopalan, V P

2017-07-01

Biofilm formation is problematic and hence undesirable in medical and industrial settings. In addition to bacteria, phototrophic organisms are an integral component of biofilms that develop on surfaces immersed in natural waters. 1-Alkyl-3-methyl imidazolium ionic liquids (IL) with varying alkyl chain length were evaluated for their influence on the formation of monospecies (Navicula sp.) and multispecies biofilms under phototrophic conditions. An IL with a long alkyl side chain, 1-hexadecyl-3-methylimidaazolium chloride ([C 16 (MIM)][Cl]) retarded growth, adhesion and biofilm formation of Navicula sp. at concentrations as low as 5μM. Interestingly, [C 16 (MIM)][Cl] was very effective in preventing multispecies phototrophic biofilms on fibre reinforced plastic surfaces immersed in natural waters (fresh and seawater). SYTOX ® Green staining and chlorophyll leakage assay confirmed that the biocidal activity of the IL was exerted through cell membrane disruption. The data show that [C 16 (MIM)][Cl] is a potent inhibitor of phototrophic biofilms at micromolar concentrations and a promising agent for biofilm control in re-circulating cooling water systems. This is the first report that ionic liquids inhibit biofilm formation by phototrophic organisms which are important members of biofilms in streams and cooling towers. Copyright © 2017 Elsevier B.V. All rights reserved.

Antigenotoxic effects of Citrus aurentium L. fruit peel oil on mutagenicity of two alkylating agents and two metals in the Drosophila wing spot test.

Science.gov (United States)

Demir, Eşref; Kocaoğlu, Serap; Cetin, Huseyin; Kaya, Bülent

2009-07-01

Antigenotoxic effects of Citrus aurentium L. (Rutaceae) fruit peel oil (CPO) in combination with mutagenic metals and alkylating agents were studied using the wing spot test of D. melanogaster. The four reference mutagens, potassium dichromate (K2Cr2O7), cobalt chloride (CoCl2), ethylmethanesulfonate (EMS), and N-ethyl-N-nitrosourea (ENU) were clearly genotoxic. CPO alone at doses from 0.1 to 0.5% in Tween 80 was not mutagenic and did not enhance the mutagenic effect of the reference mutagens. However, antigenotoxic effects of CPO were clearly demonstrated in chronic cotreatments with mutagens and oil, by a significant decrease in wing spots induced by all four mutagens. The D. melanogaster wing spot test was found to be a suitable assay for detecting antigenotoxic effects in vivo. Copyright 2009 Wiley-Liss, Inc.

HeLa cell variants that differ in sensitivity to monofunctional alkylating agents, with independence of cytotoxic and mutagenic responses

Science.gov (United States)

Baker, R. M.; Voorhis, W. C. Van; Spencer, L. A.

1979-01-01

Different strains of the established human cell line HeLa differ substantially in sensitivity to ethyl methanesulfonate (EtMes). The EtMes doses effective for either cytotoxicity or mutation induction in a line of HeLa S3 cells are about 1/10th those required in the CCL2 HeLa line of the American Type Culture Collection. By plating the sensitive HeLa S3 line in the presence of highly cytotoxic doses of EtMes, we obtained a clone (designated A6) that displays about 7-fold greater resistance to EtMes toxicity. This A6 isolate is also cross resistant to other simple monofunctional alkylating agents—exhibiting about 4-fold increased resistance to methyl methanesulfonate and 10- to 15-fold increased resistance to N-methyl-N′-nitro-N-nitrosoguanidine but is similar to the S3 parent in sensitivity to mitomycin C, UV radiation, and γ-rays. In contrast to the results for cytotoxicity, the A6 variant and the S3 parent showed the same high susceptibility to EtMes induction of ouabain-resistant mutations. This is direct biological evidence that different alkylation lesions are normally responsible for mutagenic and cytotoxic effects. The S3 and A6 cell lines may differ in DNA repair capability specific to certain potentially lethal alkylation products. The comparative sensitivity of the A6 cells to alkylation mutagenesis may also prove useful in cell genetic studies by facilitating the generation of multiple mutants for recessive alleles and permitting exceptionally sensitive detection of specific mutagenic effects. PMID:291942

Bifunctional xylanases and their potential use in biotechnology

Digital Repository Service at National Institute of Oceanography (India)

Khandeparker, R.; Numan, M.Th.

. J Chromatography 919:389–394 33. Hong SY, Lee JS, Cho KM, Math RK, Kim YH, Hong SJ, Cho YU, Kim H, Yun HD (2006) Assembling a novel bifunctional cel- lulase–xylanase from Thermotoga maritima by end-to-end fusion. Biotechnol Lett 28:1857–1862 34...

Thermogravimetric studies on alkyl methacrylate polymers and poly(alkyl methacrylate)-grafted polypropylene fibers

International Nuclear Information System (INIS)

Hayakawa, Kiyoshi; Taoda, Hiroshi; Kawase, Kaoru; Tazawa, Masato; Yamakita, Hiromi

1986-01-01

Thermal behavior of several kinds of poly (alkyl methacrylate) and polypropylene-g-poly (alkyl methacrylate) fibers prepared by γ-irradiation was investigated by thermogravimetric measurements with the intermittent analysis of the gaseous products. The degradation of poly (methyl methacrylate) proceeded according to the deploymerization mechanism reproducing the pristine monomer exclusively. The thermogram in inert atmosphere showed the features of a two-step depolymerization, while in air it showed no such a stepwise decrease with the elevating temperature. The dissolution-precipitation treatment of polymer seemed to affect the decomposition behavior. On other alkyl methacrylate polymers, the thermal decomposition generally proceeded also according to the depolymerization mechanism. But, for instance, at least two kinds of products besides its own monomer were formed from poly (isobutyl methacrylate), and their relative fractions differed with the temperature. Polypropylene-g-poly (alkyl methacrylate) fibers showed lowering of initiation temperature of decomposition with the increase in extent of the grafting, and their initiation temperatures of decomposition in air were lower than those in inert atmosphere. (author)

Effect of alkyl glycerophosphate on the activation of peroxisome proliferator-activated receptor gamma and glucose uptake in C2C12 cells

Energy Technology Data Exchange (ETDEWEB)

Tsukahara, Tamotsu, E-mail: ttamotsu@shinshu-u.ac.jp [Department of Integrative Physiology and Bio-System Control, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621 (Japan); Haniu, Hisao [Department of Orthopedic Surgery, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621 (Japan); Matsuda, Yoshikazu [Clinical Pharmacology Educational Center, Nihon Pharmaceutical University, Ina-machi, Saitama 362-0806 (Japan)

2013-04-12

Highlights: •Alkyl-LPA specifically interacts with PPARγ. •Alkyl-LPA treatments induces lipid accumulation in C2C12 cells. •Alkyl-LPA enhanced glucose uptake in C2C12 cells. •Alkyl-LPA-treated C2C12 cells express increased amounts of GLUT4 mRNA. •Alkyl-LPA is a novel therapeutic agent that can be used for the treatment of obesity and diabetes. -- Abstract: Studies on the effects of lipids on skeletal muscle cells rarely examine the effects of lysophospholipids. Through our recent studies, we identified select forms of phospholipids, such as alkyl-LPA, as ligands for the intracellular receptor peroxisome proliferator-activated receptor gamma (PPARγ). PPARγ is a nuclear hormone receptor implicated in many human diseases, including diabetes and obesity. We previously showed that alkyl-LPA is a specific agonist of PPARγ. However, the mechanism by which the alkyl-LPA–PPARγ axis affects skeletal muscle cells is poorly defined. Our objective in the present study was to determine whether alkyl-LPA and PPARγ activation promotes glucose uptake in skeletal muscle cells. Our findings indicate that PPARγ1 mRNA is more abundant than PPARγ2 mRNA in C2C12 cells. We showed that alkyl-LPA (3 μM) significantly activated PPARγ and increased intracellular glucose levels in skeletal muscle cells. We also showed that incubation of C2C12 cells with alkyl-LPA led to lipid accumulation in the cells. These findings suggest that alkyl-LPA activates PPARγ and stimulates glucose uptake in the absence of insulin in C2C12 cells. This may contribute to the plasma glucose-lowering effect in the treatment of insulin resistance.

Effect of alkyl glycerophosphate on the activation of peroxisome proliferator-activated receptor gamma and glucose uptake in C2C12 cells

International Nuclear Information System (INIS)

Tsukahara, Tamotsu; Haniu, Hisao; Matsuda, Yoshikazu

2013-01-01

Highlights: •Alkyl-LPA specifically interacts with PPARγ. •Alkyl-LPA treatments induces lipid accumulation in C2C12 cells. •Alkyl-LPA enhanced glucose uptake in C2C12 cells. •Alkyl-LPA-treated C2C12 cells express increased amounts of GLUT4 mRNA. •Alkyl-LPA is a novel therapeutic agent that can be used for the treatment of obesity and diabetes. -- Abstract: Studies on the effects of lipids on skeletal muscle cells rarely examine the effects of lysophospholipids. Through our recent studies, we identified select forms of phospholipids, such as alkyl-LPA, as ligands for the intracellular receptor peroxisome proliferator-activated receptor gamma (PPARγ). PPARγ is a nuclear hormone receptor implicated in many human diseases, including diabetes and obesity. We previously showed that alkyl-LPA is a specific agonist of PPARγ. However, the mechanism by which the alkyl-LPA–PPARγ axis affects skeletal muscle cells is poorly defined. Our objective in the present study was to determine whether alkyl-LPA and PPARγ activation promotes glucose uptake in skeletal muscle cells. Our findings indicate that PPARγ1 mRNA is more abundant than PPARγ2 mRNA in C2C12 cells. We showed that alkyl-LPA (3 μM) significantly activated PPARγ and increased intracellular glucose levels in skeletal muscle cells. We also showed that incubation of C2C12 cells with alkyl-LPA led to lipid accumulation in the cells. These findings suggest that alkyl-LPA activates PPARγ and stimulates glucose uptake in the absence of insulin in C2C12 cells. This may contribute to the plasma glucose-lowering effect in the treatment of insulin resistance

Manganese-catalyzed Dehydrogenative Alkylation or α-Olefination of Alkyl-N-Heteroaromatics by Alcohols.

Science.gov (United States)

Kempe, Rhett; Zhang, Guoying; Irrgang, Torsten; Dietel, Thomas; Kallmeier, Fabian

2018-05-02

Catalysis involving earth-abundant transition metals is an option to help save our rare noble metal resources and is especially interesting if novel reactivity or selectivity patterns are observed. We report here on a novel reaction: the dehydrogenative alkylation or α-olefination of alkyl-N-heteroaromatics by alcohols. Manganese complexes developed in our laboratory catalyze the reaction efficiently. Fe and Co complexes stabilized by such ligands are essentially inactive. Hydrogen is liberated during the reaction and bromo or iodo functional groups and olefins can be tolerated. A variety of alkyl-N-heteroaromatics can be functionalized, and benzyl and aliphatic alcohols undergo the reaction. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DNA modification by alkylating compounds

Energy Technology Data Exchange (ETDEWEB)

Kruglyakova, E.E.

1985-09-01

Results are given for research on the physico-chemical properties of alkylating compounds - nitroso alkyl ureas (NAU) which possess a broad spectrum of biological activity, such as mutagenic, carcinogenic, and anti-tumor action that is due to the alkylation and carbamoylation of DNA as well as other cellular components. Identified chemical products of NAU interaction with DNA and its components are cited. Structural conversions of a DNA macromolecule resulting from its chemical modification are examined. NAU are used to discuss possible biological consequences of DNA modification. 148 references.

Boosting Bifunctional Oxygen Electrocatalysis with 3D Graphene Aerogel-Supported Ni/MnO Particles.

Science.gov (United States)

Fu, Gengtao; Yan, Xiaoxiao; Chen, Yifan; Xu, Lin; Sun, Dongmei; Lee, Jong-Min; Tang, Yawen

2018-02-01

Electrocatalysts for oxygen-reduction and oxygen-evolution reactions (ORR and OER) are crucial for metal-air batteries, where more costly Pt- and Ir/Ru-based materials are the benchmark catalysts for ORR and OER, respectively. Herein, for the first time Ni is combined with MnO species, and a 3D porous graphene aerogel-supported Ni/MnO (Ni-MnO/rGO aerogel) bifunctional catalyst is prepared via a facile and scalable hydrogel route. The synthetic strategy depends on the formation of a graphene oxide (GO) crosslinked poly(vinyl alcohol) hydrogel that allows for the efficient capture of highly active Ni/MnO particles after pyrolysis. Remarkably, the resulting Ni-MnO/rGO aerogels exhibit superior bifunctional catalytic performance for both ORR and OER in an alkaline electrolyte, which can compete with the previously reported bifunctional electrocatalysts. The MnO mainly contributes to the high activity for the ORR, while metallic Ni is responsible for the excellent OER activity. Moreover, such bifunctional catalyst can endow the homemade Zn-air battery with better power density, specific capacity, and cycling stability than mixed Pt/C + RuO 2 catalysts, demonstrating its potential feasibility in practical application of rechargeable metal-air batteries. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Direct catalytic transformation of carbohydrates into 5-ethoxymethylfurfural with acid–base bifunctional hybrid nanospheres

International Nuclear Information System (INIS)

Li, Hu; Govind, Khokarale Santosh; Kotni, Ramakrishna; Shunmugavel, Saravanamurugan; Riisager, Anders; Yang, Song

2014-01-01

Graphical abstract: Catalytic conversion of carbohydrates into HMF and EMF in ethanol/DMSO with acid–base bifunctional hybrid nanospheres prepared from self-assembly of corresponding basic amino acids and HPA. - Highlights: • Acid–base bifunctional nanospheres were efficient for production of EMF from sugars. • Synthesis of EMF in a high yield of 76.6% was realized from fructose. • Fructose based biopolymers could also be converted into EMF with good yields. • Ethyl glucopyranoside was produced in good yields from glucose in ethanol. - Abstract: A series of acid–base bifunctional hybrid nanospheres prepared from the self-assembly of basic amino acids and phosphotungstic acid (HPA) with different molar ratios were employed as efficient and recyclable catalysts for synthesis of liquid biofuel 5-ethoxymethylfurfural (EMF) from various carbohydrates. A high EMF yield of 76.6%, 58.5%, 42.4%, and 36.5% could be achieved, when fructose, inulin, sorbose, and sucrose were used as starting materials, respectively. Although, the acid–base bifunctional nanocatalysts were inert for synthesis of EMF from glucose based carbohydrates, ethyl glucopyranoside in good yields could be obtained from glucose in ethanol. Moreover, the nanocatalyst functionalized with acid and basic sites was able to be reused several times with no significant loss in catalytic activity

Iridium-catalyzed direct synthesis of tryptamine derivatives from indoles: exploiting n-protected β-amino alcohols as alkylating agents.

Science.gov (United States)

Bartolucci, Silvia; Mari, Michele; Bedini, Annalida; Piersanti, Giovanni; Spadoni, Gilberto

2015-03-20

The selective C3-alkylation of indoles with N-protected ethanolamines involving the "borrowing hydrogen" strategy is described. This method provides convenient and sustainable access to several tryptamine derivatives.

Modulating the Optoelectronic Properties of Silver Nanowires Films: Effect of Capping Agent and Deposition Technique.

Science.gov (United States)

Lopez-Diaz, D; Merino, C; Velázquez, M M

2015-11-11

Silver nanowires 90 nm in diameter and 9 µm in length have been synthesized using different capping agents: polyvinyl pyrrolidone (PVP) and alkyl thiol of different chain lengths. The nanowire structure is not influenced by the displacement of PVP by alkyl thiols, although alkyl thiols modify the lateral aggregation of nanowires. We examined the effect of the capping agent and the deposition method on the optical and electrical properties of films prepared by Spray and the Langmuir-Schaefer methodologies. Our results revealed that nanowires capped with PVP and C8-thiol present the best optoelectronic properties. By using different deposition techniques and by modifying the nanowire surface density, we can modulate the optoelectronic properties of films. This strategy allows obtaining films with the optoelectronic properties required to manufacture touch screens and electromagnetic shielding.

Reactions of 4-nitro-1,2,3-triazole with alkylating agents and compounds with activated multiple bonds

Energy Technology Data Exchange (ETDEWEB)

Vereshchagin, L.I.; Kuznetsova, N.I.; Kirillova, L.P.; Shcherbakov, V.V.; Sukhanov, G.T.; Gareev, G.A.

1987-01-01

When 4-nitro-1,2,3-triazole is alkylated, a mixture of N1- and N2-isomers is formed, with the latter usually predominating. The same behavior is also observed in addition reactions of 4-nitrotriazole to activated multiple bonds.

DNA damage induced in mouse peritoneal exudate cells after in vivo administration of chemical and physical agents as determined by alkaline elution

International Nuclear Information System (INIS)

Nishi, Yoshisuke; Miyanaga, Kumiko; Sato, Sei-ichi; Inui, Naomichi

1990-01-01

The alkaline elution technique for detecting DNA strand breaks has been applied to the study of DNA damage in mouse peritoneal exudate cells resulting from the in vivo administration of chemical and physical agents. The direct methylating agents methyl methanesulphonate and N-methyl-N-nitrosourea induced extensive breakage in samples taken 2 h after administration. The direct ethylating agents ethyl methanesulphonate and N-ethyl-N-nitrosourea also induced DNA strand breaks, but to a lesser extent than the methylating agents. The indirect methylating agent dimethylnitrosamine showed hardly any effect in this system. A weak but positive response was observed upon treatment with the anti-neoplastic alkylating agent procarbazine hydrochloride. The whole-body irradiation of mice with 60 Co γ-rays also induced DNA strand breaks. The elution profiles for γ-ray irradiation were different from those of alkylating agents, and indicate that alkylating agents produce many more secondary lesions leading to DNA strand breaks than γ-rays. N-methyl-N-nitrosourea produced slightly more DNA strand breaks in mutagen-sensitive mice, which are derived from the CD-1 strain, than in ICR mice. (Author)

DNA damage induced in mouse peritoneal exudate cells after in vivo administration of chemical and physical agents as determined by alkaline elution

Energy Technology Data Exchange (ETDEWEB)

Nishi, Yoshisuke (Japan Tobacco Inc., Yokohama (Japan). Central Research Inst.); Miyanaga, Kumiko; Sato, Sei-ichi (Japan Tobacco Inc., Hatano, Kanagawa (Japan). Toxicology Research Lab.); Inui, Naomichi (Japan Tobacco Inc., Yokohama, Kanagawa (Japan). Pharmaceutical Research Labs.)

1990-01-01

The alkaline elution technique for detecting DNA strand breaks has been applied to the study of DNA damage in mouse peritoneal exudate cells resulting from the in vivo administration of chemical and physical agents. The direct methylating agents methyl methanesulphonate and N-methyl-N-nitrosourea induced extensive breakage in samples taken 2 h after administration. The direct ethylating agents ethyl methanesulphonate and N-ethyl-N-nitrosourea also induced DNA strand breaks, but to a lesser extent than the methylating agents. The indirect methylating agent dimethylnitrosamine showed hardly any effect in this system. A weak but positive response was observed upon treatment with the anti-neoplastic alkylating agent procarbazine hydrochloride. The whole-body irradiation of mice with {sup 60}Co {gamma}-rays also induced DNA strand breaks. The elution profiles for {gamma}-ray irradiation were different from those of alkylating agents, and indicate that alkylating agents produce many more secondary lesions leading to DNA strand breaks than {gamma}-rays. N-methyl-N-nitrosourea produced slightly more DNA strand breaks in mutagen-sensitive mice, which are derived from the CD-1 strain, than in ICR mice. (Author).

Mycothiol-Deficient Mycobacterium smegmatis Mutants Are Hypersensitive to Alkylating Agents, Free Radicals, and Antibiotics

Science.gov (United States)

Rawat, Mamta; Newton, Gerald L.; Ko, Mary; Martinez, Gladys J.; Fahey, Robert C.; Av-Gay, Yossef

2002-01-01

Mycothiol (MSH; 1d-myo-inosityl 2-[N-acetyl-l-cysteinyl]amido-2-deoxy-α-d-glucopyranoside) is the major low-molecular-weight thiol produced by mycobacteria. Mutants of Mycobacterium smegmatis mc2155 deficient in MSH production were produced by chemical mutagenesis as well as by transposon mutagenesis. One chemical mutant (mutant I64) and two transposon mutants (mutants Tn1 and Tn2) stably deficient in MSH production were isolated by screening for reduced levels of MSH content. The MSH contents of transposon mutants Tn1 and Tn2 were found to be less than 0.1% that of the parent strain, and the MSH content of I64 was found to be 1 to 5% that of the parent strain. All three strains accumulated 1d-myo-inosityl 2-deoxy-α-d-glucopyranoside to levels 20- to 25-fold the level found in the parent strain. The cysteine:1d-myo-inosityl 2-amino-2-deoxy-α-d-glucopyranoside ligase (MshC) activities of the three mutant strains were ≤2% that of the parent strain. Phenotypic analysis revealed that these MSH-deficient mutants possess increased susceptibilities to free radicals and alkylating agents and to a wide range of antibiotics including erythromycin, azithromycin, vancomycin, penicillin G, rifamycin, and rifampin. Conversely, the mutants possess at least 200-fold higher levels of resistance to isoniazid than the wild type. We mapped the mutation in the chemical mutant by sequencing the mshC gene and showed that a single amino acid substitution (L205P) is responsible for reduced MSH production and its associated phenotype. Our results demonstrate that there is a direct correlation between MSH depletion and enhanced sensitivity to toxins and antibiotics. PMID:12384335

PARP-1 modulation of mTOR signaling in response to a DNA alkylating agent.

Directory of Open Access Journals (Sweden)

Chantal Ethier

Full Text Available Poly(ADP-ribose polymerase-1 (PARP-1 is widely involved in cell death responses. Depending on the degree of injury and on cell type, PARP activation may lead to autophagy, apoptosis or necrosis. In HEK293 cells exposed to the alkylating agent N-methyl-N'-nitro-N'-nitrosoguanine (MNNG, we show that PARP-1 activation triggers a necrotic cell death response. The massive poly(ADP-ribose (PAR synthesis following PARP-1 activation leads to the modulation of mTORC1 pathway. Shortly after MNNG exposure, NAD⁺ and ATP levels decrease, while AMP levels drastically increase. We characterized at the molecular level the consequences of these altered nucleotide levels. First, AMP-activated protein kinase (AMPK is activated and the mTORC1 pathway is inhibited by the phosphorylation of Raptor, in an attempt to preserve cellular energy. Phosphorylation of the mTORC1 target S6 is decreased as well as the phosphorylation of the mTORC2 component Rictor on Thr1135. Finally, Akt phosphorylation on Ser473 is lost and then, cell death by necrosis occurs. Inhibition of PARP-1 with the potent PARP inhibitor AG14361 prevents all of these events. Moreover, the antioxidant N-acetyl-L-cysteine (NAC can also abrogate all the signaling events caused by MNNG exposure suggesting that reactive oxygen species (ROS production is involved in PARP-1 activation and modulation of mTOR signaling. In this study, we show that PARP-1 activation and PAR synthesis affect the energetic status of cells, inhibit the mTORC1 signaling pathway and possibly modulate the mTORC2 complex affecting cell fate. These results provide new evidence that cell death by necrosis is orchestrated by the balance between several signaling pathways, and that PARP-1 and PAR take part in these events.

Synergistic Interaction within Bifunctional Ruthenium Nanoparticle/SILP Catalysts for the Selective Hydrodeoxygenation of Phenols.

Science.gov (United States)

Luska, Kylie L; Migowski, Pedro; El Sayed, Sami; Leitner, Walter

2015-12-21

Ruthenium nanoparticles immobilized on acid-functionalized supported ionic liquid phases (Ru NPs@SILPs) act as efficient bifunctional catalysts in the hydrodeoxygenation of phenolic substrates under batch and continuous flow conditions. A synergistic interaction between the metal sites and acid groups within the bifunctional catalyst leads to enhanced catalytic activities for the overall transformation as compared to the individual steps catalyzed by the separate catalytic functionalities. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pseudomonas putida AlkA and AlkB Proteins Comprise Different Defense Systems for the Repair of Alkylation Damage to DNA – In Vivo, In Vitro, and In Silico Studies

Science.gov (United States)

Mielecki, Damian; Saumaa, Signe; Wrzesiński, Michał; Maciejewska, Agnieszka M.; Żuchniewicz, Karolina; Sikora, Anna; Piwowarski, Jan; Nieminuszczy, Jadwiga; Kivisaar, Maia; Grzesiuk, Elżbieta

2013-01-01

Alkylating agents introduce cytotoxic and/or mutagenic lesions to DNA bases leading to induction of adaptive (Ada) response, a mechanism protecting cells against deleterious effects of environmental chemicals. In Escherichia coli, the Ada response involves expression of four genes: ada, alkA, alkB, and aidB. In Pseudomonas putida, the organization of Ada regulon is different, raising questions regarding regulation of Ada gene expression. The aim of the presented studies was to analyze the role of AlkA glycosylase and AlkB dioxygenase in protecting P. putida cells against damage to DNA caused by alkylating agents. The results of bioinformatic analysis, of survival and mutagenesis of methyl methanesulfonate (MMS) or N-methyl-N’-nitro-N-nitrosoguanidine (MNNG) treated P. putida mutants in ada, alkA and alkB genes as well as assay of promoter activity revealed diverse roles of Ada, AlkA and AlkB proteins in protecting cellular DNA against alkylating agents. We found AlkA protein crucial to abolish the cytotoxic but not the mutagenic effects of alkylans since: (i) the mutation in the alkA gene was the most deleterious for MMS/MNNG treated P. putida cells, (ii) the activity of the alkA promoter was Ada-dependent and the highest among the tested genes. P. putida AlkB (PpAlkB), characterized by optimal conditions for in vitro repair of specific substrates, complementation assay, and M13/MS2 survival test, allowed to establish conservation of enzymatic function of P. putida and E. coli AlkB protein. We found that the organization of P. putida Ada regulon differs from that of E. coli. AlkA protein induced within the Ada response is crucial for protecting P. putida against cytotoxicity, whereas Ada prevents the mutagenic action of alkylating agents. In contrast to E. coli AlkB (EcAlkB), PpAlkB remains beyond the Ada regulon and is expressed constitutively. It probably creates a backup system that protects P. putida strains defective in other DNA repair systems against

[Multiple organ failure presumably due to alkylating agents used as preconditioning drugs for autologous peripheral blood stem cell transplantation in an acute promyelocytic leukemia].

Science.gov (United States)

Ida, Tori; Hashimoto, Shigeo; Suzuki, Nobuaki; Ebe, Yusuke; Yano, Toshio; Sato, Naoko; Koike, Tadashi

2016-01-01

A 52-year-old male was diagnosed as having acute promyelocytic leukemia (APL) in 2006. He received induction chemotherapy including all-trans retinoic acid and initially achieved a complete remission (CR). After several courses of consolidation therapy combining anthracyclines and cytarabine, he maintained CR. In 2009, an APL relapse was diagnosed, and he was treated with arsenic trioxide. Since he achieved a second CR, he underwent autologous peripheral blood stem cell transplantation (auto-PBSCT) with a conditioning regimen consisting of busulfan and melphalan. At four months after auto-PBSCT, he developed a pneumothorax and acute respiratory failure. He died despite intensive therapy. Autopsy findings included various atypical and apoptotic cells in his pulmonary tissue. These changes were confirmed in multiple organs throughout the body, suggesting them to be drug-induced. The findings in this case suggested multiple organ failure due to alkylating agents.

Environmentally Benign Bifunctional Solid Acid and Base Catalysts

NARCIS (Netherlands)

Elmekawy, A.; Shiju, N.R.; Rothenberg, G.; Brown, D.R.

2014-01-01

Solid bifunctional acid-​base catalysts were prepd. in two ways on an amorphous silica support: (1) by grafting mercaptopropyl units (followed by oxidn. to propylsulfonic acid) and aminopropyl groups to the silica surface (NH2-​SiO2-​SO3H)​, and (2) by grafting only aminopropyl groups and then

Nanostructured poly(benzimidazole membranes by N-alkylation

Directory of Open Access Journals (Sweden)

J. Weber

2014-01-01

Full Text Available Modification of poly(benzimidazole (PBI by N-alkylation leads to polymers capable of undergoing microphase separation. Polymers with different amounts of C18 alkyl chains have been prepared. The polymers were analyzed by spectroscopy, thermal analysis, electron microscopy and X-ray scattering. The impact of the amount of alkyl chains on the observed microphase separation was analyzed. Membranes prepared from the polymers do show microphase separation, as evidenced by scattering experiments. While no clear morphology could be derived for the domains in the native state, evidence for the formation of lamellar morphologies upon doping with phosphoric acid is provided. Finally, the proton conductivity of alkyl-modified PBI is compared with that of pure PBI, showing that the introduction of alkyl side chains does not result in significant conductivity changes.

Modulating the Optoelectronic Properties of Silver Nanowires Films: Effect of Capping Agent and Deposition Technique

Directory of Open Access Journals (Sweden)

D. Lopez-Diaz

2015-11-01

Full Text Available Silver nanowires 90 nm in diameter and 9 µm in length have been synthesized using different capping agents: polyvinyl pyrrolidone (PVP and alkyl thiol of different chain lengths. The nanowire structure is not influenced by the displacement of PVP by alkyl thiols, although alkyl thiols modify the lateral aggregation of nanowires. We examined the effect of the capping agent and the deposition method on the optical and electrical properties of films prepared by Spray and the Langmuir-Schaefer methodologies. Our results revealed that nanowires capped with PVP and C8-thiol present the best optoelectronic properties. By using different deposition techniques and by modifying the nanowire surface density, we can modulate the optoelectronic properties of films. This strategy allows obtaining films with the optoelectronic properties required to manufacture touch screens and electromagnetic shielding.

Enhancement of alkylation catalysts for improved supercritical fluid regeneration

Science.gov (United States)

Ginosar, Daniel M.; Petkovic, Lucia M.

2010-12-28

A method of modifying an alkylation catalyst to reduce the formation of condensed hydrocarbon species thereon. The method comprises providing an alkylation catalyst comprising a plurality of active sites. The plurality of active sites on the alkylation catalyst may include a plurality of weakly acidic active sites, intermediate acidity active sites, and strongly acidic active sites. A base is adsorbed to a portion of the plurality of active sites, such as the strongly acidic active sites, selectively poisoning the strongly acidic active sites. A method of modifying the alkylation catalyst by providing an alkylation catalyst comprising a pore size distribution that sterically constrains formation of the condensed hydrocarbon species on the alkylation catalyst or by synthesizing the alkylation catalyst to comprise a decreased number of strongly acidic active sites is also disclosed, as is a method of improving a regeneration efficiency of the alkylation catalyst.

Induction of dominant lethal mutations by alkylating agnets in germ-cells of the silkworm, Bombyx mori

International Nuclear Information System (INIS)

Murota, Tetsuo; Murakami, Akio.

1977-01-01

The comparison of the intensity of activity was made by measuring radiation equivalent chemical (REC) dose in the experiment of the induction of dominant lethal mutation, using the germ cells of pupae five days before the moths will be hatched. The alkylating agents employed in the experiment are methyl methanesulfonate (MMS), ethyl methanesulfonate (EMS), diethyl sulfate (DSC) and mitomycine-C (MC). X-ray irradiation was employed in order to indicate the capability of inducing mutation of the alkylating agents with the radiation equivalent chemical dose (REC dose). The dose-hatchability curves for the alkylating agents showed sigmoidal fashion as observed in X-ray, regardless of germ cells. The REC value at LD (50) was estimated by comparing the relative mutagenic capability of these chemicals. In sperm, EMS and DES with concentration of 1.0 x 10 -7 M/g showed the same lethality as about 2.3 kR and 0.6 kR of X-ray. However, no significant reduction of embryonic lethality after the treatment of pupae with MC (up to 2.1 x 10 -7 M/g) and MMS (up to 1.0 x 10 -6 M/g) was observed. As the results, the order of mutagenic effectiveness was as follows: EMS>DES>MMS approximately equal to MC. When oocytes in the mid-pupae were treated with MMS, EMS and MC with concentration of 1.0 x 10 -7 M/g, MMS and EMS showed the same effects as 12.8 kR and 0.6 kR. Surprisingly, MC showed the same lethality as 232.3 kR. This extremely high sensitivity of oocytes to MC may be ascribed to the inhibiting effect of the drug on the meiotic division. (Iwakiri, K.)

DNA alkylation lesions and their repair in human cells: modification of the comet assay with 3-methyladenine DNA glycosylase (AlkD).

Science.gov (United States)

Hašplová, Katarína; Hudecová, Alexandra; Magdolénová, Zuzana; Bjøras, Magnar; Gálová, Eliška; Miadoková, Eva; Dušinská, Mária

2012-01-05

3-methyladenine DNA glycosylase (AlkD) belongs to a new family of DNA glycosylases; it initiates repair of cytotoxic and promutagenic alkylated bases (its main substrates being 3-methyladenine and 7-methylguanine). The modification of the comet assay (single cell gel electrophoresis) using AlkD enzyme thus allows assessment of specific DNA alkylation lesions. The resulting baseless sugars are alkali-labile, and under the conditions of the alkaline comet assay they appear as DNA strand breaks. The alkylating agent methyl methanesulfonate (MMS) was used to induce alkylation lesions and to optimize conditions for the modified comet assay method with AlkD on human lymphoblastoid (TK6) cells. We also studied cellular and in vitro DNA repair of alkylated bases in DNA in TK6 cells after treatment with MMS. Results from cellular repair indicate that 50% of DNA alkylation is repaired in the first 60 min. The in vitro repair assay shows that while AlkD recognises most alkylation lesions after 60 min, a cell extract from TK6 cells recognises most of the MMS-induced DNA adducts already in the first 15 min of incubation, with maximum detection of lesions after 60 min' incubation. Additionally, we tested the in vitro repair capacity of human lymphocyte extracts from 5 individuals and found them to be able to incise DNA alkylations in the same range as AlkD. The modification of the comet assay with AlkD can be useful for in vitro and in vivo genotoxicity studies to detect alkylation damage and repair and also for human biomonitoring and molecular epidemiology studies. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Bifunctional electrodes for unitised regenerative fuel cells

International Nuclear Information System (INIS)

Altmann, Sebastian; Kaz, Till; Friedrich, Kaspar Andreas

2011-01-01

Research highlights: → Different oxygen electrode configurations for the operation in a unitised reversible fuel cell were tested. → Polarisation curves and EIS measurements were recorded. → The mixture of catalysts performs best for the present stage of electrode development. → Potential improvements for the different compositions are discussed. - Abstract: The effects of different configurations and compositions of platinum and iridium oxide electrodes for the oxygen reaction of unitised regenerative fuel cells (URFC) are reported. Bifunctional oxygen electrodes are important for URFC development because favourable properties for the fuel cell and the electrolysis modes must be combined into a single electrode. The bifunctional electrodes were studied under different combinations of catalyst mixtures, multilayer arrangements and segmented configurations with single catalyst areas. Distinct electrochemical behaviour was observed for both modes and can be explained on the basis of impedance spectroscopy. The mixture of both catalysts performs best for the present stage of electrode development. Also, the multilayer electrodes yielded good results with the potential for optimisation. The influence of ionic and electronic resistances on the relative performance is demonstrated. However, penalties due to cross currents in the heterogeneous electrodes were identified and explained by comparing the performance curves with electrodes composed of a single catalyst. Potential improvements for the different compositions are discussed.

Evaluation of the mutagenicity of alkylating agents, methylnitrosourea and temozolomide, using the rat Pig-a assay with total red blood cells or reticulocytes.

Science.gov (United States)

Muto, Shigeharu; Yamada, Katsuya; Kato, Tatsuya; Ando, Masamitsu; Inoue, Yoshimi; Iwase, Yumiko; Uno, Yoshifumi

2016-11-15

A collaborative study of the endogenous phosphatidylinositol glycan class A (Pig-a) gene mutation assay was conducted by the Japanese Environmental Mutagen Society/Mammalian Mutagenicity Study Group with a single-dosing regimen of test chemicals administered to male rats. As a part of the study, two DNA alkylating agents, methylnitrosourea (MNU) and temozolomide (TMZ), were dosed by single oral gavage at 25, 50, and 100mg/kg body weight. Pig-a mutant analysis of total red blood cells (RBCs; RBC Pig-a assay) and reticulocytes (RETs; PIGRET assay) was performed on Days 8, 15 and 29 after the administration. Both chemicals increased Pig-a mutants among RBCs and RETs with dose dependency on all days examined. The mutant frequencies were higher among RETs compared with RBCs, indicating that the PIGRET assay could detect mutagenicity more sensitively than the RBC Pig-a assay after a single dose of test chemicals. Copyright © 2016 Elsevier B.V. All rights reserved.

RELATIONSHIPS BETWEEN ABLATION OF DISTINCT HEMATOPOIETIC-CELL SUBSETS AND THE DEVELOPMENT OF DONOR BONE-MARROW ENGRAFTMENT FOLLOWING RECIPIENT PRETREATMENT WITH DIFFERENT ALKYLATING DRUGS

NARCIS (Netherlands)

DOWN, JD; BOUDEWIJN, A; DILLINGH, JH; FOX, BW; PLOEMACHER, RE

1994-01-01

A number of different alkylating chemotherapeutic agents - busulphan, dimethylbusulphan (DMB), isopropylmethane sulphonate (IMS), melphalan, cyclophosphamide (CY) and bischloroethylnitrosourea (BCNU)- were investigated for their cytotoxic effects on different haemopoietic cell populations in host

Effect of green juice and their bioactive compounds on genotoxicity induced by alkylating agents in mice.

Science.gov (United States)

Fagundes, Gabriela Elibio; Damiani, Adriani Paganini; Borges, Gabriela Daminelli; Teixeira, Karina Oliveira; Jesus, Maiellen Martins; Daumann, Francine; Ramlov, Fernanda; Carvalho, Tiago; Leffa, Daniela Dimer; Rohr, Paula; Moraes De Andrade, Vanessa

2017-01-01

Kale juice (Brassica oleracea L. var. acephala D.C.) is a reliable source of dietary carotenoids and typically contains the highest concentrations of lutein (LT) and beta-carotene (BC) among green leafy vegetables. As a result of their antioxidant properties, dietary carotenoids are postulated to decrease the risk of disease occurrence, particularly certain cancers. The present study aimed to (1) examine the genotoxic and antigenotoxic activity of natural and commercially available juices derived from Brassica oleracea and (2) assess influence of LT or BC against DNA damage induced by alkylating agents such as methyl methanesulfonate (MS) or cyclophosphamide (CP) in vivo in mice. Male Swiss mice were divided into groups of 6 animals, which were treated with water, natural, or commercial Brassica oleraceae juices (kale), LT, BC, MMS, or CP. After treatment, DNA damage was determined in peripheral blood lymphocytes using the comet assay. Results demonstrated that none of the Brassica oleraceae juices or carotenoids produced genotoxic effects. In all examined cell types, kale juices or carotenoids inhibited DNA damage induced by MMS or CP administered either pre- or posttreatment by 50 and 20%, respectively. Under our experimental conditions, kale leaf juices alone exerted no marked genotoxic or clastogenic effects. However, a significant decrease in DNA damage induced by MMS or CP was noted. This effect was most pronounced in groups that received juices, rather than carotenoids, suggesting that the synergy among constituents present in the food matrix may be more beneficial than the action of single compounds. Data suggest that the antigenotoxic properties of kale juices may be of therapeutic importance.

N-Alkylation by Hydrogen Autotransfer Reactions.

Science.gov (United States)

Ma, Xiantao; Su, Chenliang; Xu, Qing

2016-06-01

Owing to the importance of amine/amide derivatives in all fields of chemistry, and also the green and environmentally benign features of using alcohols as alkylating reagents, the relatively high atom economic dehydrative N-alkylation reactions of amines/amides with alcohols through hydrogen autotransfer processes have received much attention and have developed rapidly in recent decades. Various efficient homogeneous and heterogeneous transition metal catalysts, nano materials, electrochemical methods, biomimetic methods, asymmetric N-alkylation reactions, aerobic oxidative methods, and even certain transition metal-free, catalyst-free, or autocatalyzed methods, have also been developed in recent years. With a brief introduction to the background and developments in this area of research, this chapter focuses mainly on recent progress and technical and conceptual advances contributing to the development of this research in the last decade. In addition to mainstream research on homogeneous and heterogeneous transition metal-catalyzed reactions, possible mechanistic routes for hydrogen transfer and alcohol activation, which are key processes in N-alkylation reactions but seldom discussed in the past, the recent reports on computational mechanistic studies of the N-alkylation reactions, and the newly emerged N-alkylation methods based on novel alcohol activation protocols such as air-promoted reactions and transition metal-free methods, are also reviewed in this chapter. Problems and bottlenecks that remained to be solved in the field, and promising new research that deserves greater future attention and effort, are also reviewed and discussed.

Preparation of trialkylindium by alkylation of metallic indium

International Nuclear Information System (INIS)

Eremeev, I.V.; Danov, S.M.; Sakhipov, V.R.

1995-01-01

The investigation results on production of trialkyl indium by alkylation of metallic indium are presented. In contradistinction to the known techniques for the production of trialkyls on indium by alkylation it is suggested to separate the synthesis into two steps. At the first step indium is alkylated by alkylhalide to alkyl indium halide, and at the second alkylation is carried out using. Grignard reagent. The techniques for preparation of trimethyl- and triethylindium, developed on the bases of this scheme, are noted for good reproducibility, allow to preclude, agglomeration of indium during the synthesis, as well as to reduce the consumption coefficients, and amounts, of the introduced starting reagents, i.e. magnesium and alkylhalide. Refs. 16

Non-random alkylation of DNA sequences induced in vivo by chemical mutagens

Energy Technology Data Exchange (ETDEWEB)

Durante, M.; Geri, C.; Bonatti, S.; Parenti, R. (Universita di Pisa (Italy))

1989-08-01

Previous studies of the interaction of alkylating agents on the eukaryotic genome support the idea that induction of DNA adducts is at specific genomic sites. Here we show molecular and cytological evidence that alkylation is rather specific. Mammalian cell cultures were exposed to different doses of mutagens and the DNA was analyzed by density gradient ultracentrifugation, hydroxylapatite fractionation, and by restriction enzyme analysis. Studies with the labelled mutagens N-ethyl-N-nitrosourea and N-methyl-N'-nitro-N-nitrosoguanidine show that there is a non-random distribution of the adducts. The adducts are found more frequently in A-T, G-C rich satellite DNA and highly repetitive sequences. Analysis with restriction enzymes shows that both methyl and ethyl groups influence the restriction patterns of the enzymes HpaII and MspI that recognize specific endogenous DNA methylation. These data suggest, as a subsequent mechanism, a modification in the pattern of the normal endogenous methylation of 5-methylcytosine.

Investigation of Unanticipated Alkylation at the N(π) Position of a Histidyl Residue Under Mitsunobu Conditions and Synthesis of Orthogonally Protected Histidine Analogues

Science.gov (United States)

Qian, Wenjian; Liu, Fa; Burke, Terrence R.

2011-01-01

We had previously reported that Mitsunobu-based introduction of alkyl substituents onto the imidazole N(π)-position of a key histidine residue in phosphothreonine-containing peptides can impart high binding affinity against the polo box domain of polo like kinase 1. Our current paper investigates the mechanism leading to this N(π)-alkylation and provides synthetic methodologies that permit the facile synthesis of histidine N(π)-modified peptides. These agents represent new and potentially important tools for biological studies. PMID:21950469

Nuclear translocation of mismatch repair proteins MSH2 and MSH6 as a response of cells to alkylating agents.

Science.gov (United States)

Christmann, M; Kaina, B

2000-11-17

Mammalian mismatch repair has been implicated in mismatch correction, the prevention of mutagenesis and cancer, and the induction of genotoxicity and apoptosis. Here, we show that treatment of cells specifically with agents inducing O(6)-methylguanine in DNA, such as N-methyl-N'-nitro-N-nitrosoguanidine and N-methyl-N-nitrosourea, elevates the level of MSH2 and MSH6 and increases GT mismatch binding activity in the nucleus. This inducible response occurs immediately after alkylation, is long-lasting and dose-dependent, and results from translocation of the preformed MutSalpha complex (composed of MSH2 and MSH6) from the cytoplasm into the nucleus. It is not caused by an increase in MSH2 gene activity. Cells expressing the DNA repair protein O(6)-methylguanine-DNA methyltransferase (MGMT), thus having the ability to repair O(6)-methylguanine, showed no translocation of MutSalpha, whereas inhibition of MGMT by O(6)-benzylguanine provoked the translocation. The results demonstrate that O(6)-methylguanine lesions are involved in triggering nuclear accumulation of MSH2 and MSH6. The finding that treatment of cells with O(6)-methylguanine-generating mutagens results in an increase of MutSalpha and GT binding activity in the nucleus indicates a novel type of genotoxic stress response.

Bifunctional electrode performance for zinc-air flow cells with pulse charging

International Nuclear Information System (INIS)

Pichler, Birgit; Weinberger, Stephan; Reščec, Lucas; Grimmer, Ilena; Gebetsroither, Florian; Bitschnau, Brigitte; Hacker, Viktor

2017-01-01

Highlights: •Manufacture of bi-catalyzed bifunctional air electrodes via scalable process. •Direct synthesis of NiCo 2 O 4 on carbon nanofibers or nickel powder support. •450 charge and discharge cycles over 1000 h at 50 mA cm −2 demonstrated. •Pulse charging with 150 mA cm −2 is successfully applied on air electrodes. •Charge and discharge ΔV of <0.8 V at 50 mA cm −2 when supplied with O 2. -- Abstract: Bifunctional air electrodes with tuned composition consisting of two precious metal-free oxide catalysts are manufactured for application in rechargeable zinc-air flow batteries and electrochemically tested via long-term pulse charge and discharge cycling experiments at 50 mA cm −2 (mean). NiCo 2 O 4 spinel, synthesized via direct impregnation on carbon nanofibers or nickel powder and characterized by energy dispersive X-ray spectroscopy and X-ray diffraction experiments, shows high activity toward oxygen evolution reaction with low charge potentials of < 2.0 V vs. Zn/Zn 2+ . La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 perovskite exhibits bifunctional activity and outperforms the NiCo 2 O 4 spinel in long-term stability tenfold. By combining the catalysts in one bi-catalyzed bifunctional air electrode, stable performances of more than 1000 h and 450 cycles are achieved when supplied with oxygen and over 650 h and 300 cycles when supplied with synthetic air. In addition, the pulse charging method, which is beneficial for compact zinc deposition, is successfully tested on air electrodes during long-term operation. The oxygen evolution potentials during pulse, i.e. at tripled charge current density of 150 mA cm −2 , are only 0.06–0.08 V higher compared to constant charging current densities. Scanning electron microscopy confirms that mechanical degradation caused by bubble formation during oxygen evolution results in slowly decreasing discharge potentials.

Pseudomonas putida AlkA and AlkB proteins comprise different defense systems for the repair of alkylation damage to DNA - in vivo, in vitro, and in silico studies.

Directory of Open Access Journals (Sweden)

Damian Mielecki

Full Text Available Alkylating agents introduce cytotoxic and/or mutagenic lesions to DNA bases leading to induction of adaptive (Ada response, a mechanism protecting cells against deleterious effects of environmental chemicals. In Escherichia coli, the Ada response involves expression of four genes: ada, alkA, alkB, and aidB. In Pseudomonas putida, the organization of Ada regulon is different, raising questions regarding regulation of Ada gene expression. The aim of the presented studies was to analyze the role of AlkA glycosylase and AlkB dioxygenase in protecting P. putida cells against damage to DNA caused by alkylating agents. The results of bioinformatic analysis, of survival and mutagenesis of methyl methanesulfonate (MMS or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG treated P. putida mutants in ada, alkA and alkB genes as well as assay of promoter activity revealed diverse roles of Ada, AlkA and AlkB proteins in protecting cellular DNA against alkylating agents. We found AlkA protein crucial to abolish the cytotoxic but not the mutagenic effects of alkylans since: (i the mutation in the alkA gene was the most deleterious for MMS/MNNG treated P. putida cells, (ii the activity of the alkA promoter was Ada-dependent and the highest among the tested genes. P. putida AlkB (PpAlkB, characterized by optimal conditions for in vitro repair of specific substrates, complementation assay, and M13/MS2 survival test, allowed to establish conservation of enzymatic function of P. putida and E. coli AlkB protein. We found that the organization of P. putida Ada regulon differs from that of E. coli. AlkA protein induced within the Ada response is crucial for protecting P. putida against cytotoxicity, whereas Ada prevents the mutagenic action of alkylating agents. In contrast to E. coli AlkB (EcAlkB, PpAlkB remains beyond the Ada regulon and is expressed constitutively. It probably creates a backup system that protects P. putida strains defective in other DNA repair systems

Bifunctional fluorescent probes for detection of amyloid aggregates and reactive oxygen species.

Science.gov (United States)

Needham, Lisa-Maria; Weber, Judith; Fyfe, James W B; Kabia, Omaru M; Do, Dung T; Klimont, Ewa; Zhang, Yu; Rodrigues, Margarida; Dobson, Christopher M; Ghandi, Sonia; Bohndiek, Sarah E; Snaddon, Thomas N; Lee, Steven F

2018-02-01

Protein aggregation into amyloid deposits and oxidative stress are key features of many neurodegenerative disorders including Parkinson's and Alzheimer's disease. We report here the creation of four highly sensitive bifunctional fluorescent probes, capable of H 2 O 2 and/or amyloid aggregate detection. These bifunctional sensors use a benzothiazole core for amyloid localization and boronic ester oxidation to specifically detect H 2 O 2 . We characterized the optical properties of these probes using both bulk fluorescence measurements and single-aggregate fluorescence imaging, and quantify changes in their fluorescence properties upon addition of amyloid aggregates of α-synuclein and pathophysiological H 2 O 2 concentrations. Our results indicate these new probes will be useful to detect and monitor neurodegenerative disease.

Bifunctional fluorescent probes for detection of amyloid aggregates and reactive oxygen species

Science.gov (United States)

Needham, Lisa-Maria; Weber, Judith; Fyfe, James W. B.; Kabia, Omaru M.; Do, Dung T.; Klimont, Ewa; Zhang, Yu; Rodrigues, Margarida; Dobson, Christopher M.; Ghandi, Sonia; Bohndiek, Sarah E.; Snaddon, Thomas N.; Lee, Steven F.

2018-02-01

Protein aggregation into amyloid deposits and oxidative stress are key features of many neurodegenerative disorders including Parkinson's and Alzheimer's disease. We report here the creation of four highly sensitive bifunctional fluorescent probes, capable of H2O2 and/or amyloid aggregate detection. These bifunctional sensors use a benzothiazole core for amyloid localization and boronic ester oxidation to specifically detect H2O2. We characterized the optical properties of these probes using both bulk fluorescence measurements and single-aggregate fluorescence imaging, and quantify changes in their fluorescence properties upon addition of amyloid aggregates of α-synuclein and pathophysiological H2O2 concentrations. Our results indicate these new probes will be useful to detect and monitor neurodegenerative disease.

Astaxanthin diferulate as a bifunctional antioxidant

DEFF Research Database (Denmark)

Papa, T.B.R.; Pinho, V.D.; Nascimento, E.P. do

2015-01-01

Abstract Astaxanthin when esterified with ferulic acid is better singlet oxygen quencher with k2 = (1.58 ± 0.1) 10(10) L mol(- 1)s(- 1) in ethanol at 25°C compared with astaxanthin with k2 = (1.12 ± 0.01) 10(9) L mol(- 1)s(- 1). The ferulate moiety in the astaxanthin diester is a better radical....... The mutual enhancement of antioxidant activity for the newly synthetized astaxanthin diferulate becoming a bifunctional antioxidant is rationalized according to a two-dimensional classification plot for electron donation and electron acceptance capability....

The combination of BH3-mimetic ABT-737 with the alkylating agent temozolomide induces strong synergistic killing of melanoma cells independent of p53.

Directory of Open Access Journals (Sweden)

Steven N Reuland

Full Text Available Metastatic melanoma has poor prognosis and is refractory to most conventional chemotherapies. The alkylating agent temozolomide (TMZ is commonly used in treating melanoma but has a disappointing response rate. Agents that can act cooperatively with TMZ and improve its efficacy are thus highly sought after. The BH3 mimetic ABT-737, which can induce apoptosis by targeting pro-survival Bcl-2 family members, has been found to enhance the efficacy of many conventional chemotherapeutic agents in multiple cancers. We found that combining TMZ and ABT-737 induced strong synergistic apoptosis in multiple human melanoma cell lines. When the drugs were used in combination in a mouse xenograft model, they drastically reduced tumor growth at concentrations where each individual drug had no significant effect. We found that TMZ treatment elevated p53 levels, and that the pro-apoptotic protein Noxa was elevated in TMZ/ABT-737 treated cells. Experiments with shRNA demonstrated that the synergistic effect of TMZ and ABT-737 was largely dependent on Noxa. Experiments with nutlin-3, a p53 inducer, demonstrated that p53 induction was sufficient for synergistic cell death with ABT-737 in a Noxa-dependent fashion. However, p53 was not necessary for TMZ/ABT-737 synergy as demonstrated by a p53-null line, indicating that TMZ and ABT-737 together induce Noxa in a p53-independent fashion. These results demonstrate that targeting anti-apoptotic Bcl-2 members is a promising method for treating metastatic melanoma, and that clinical trials with TMZ and Bcl-2 inhibitors are warranted.

Programmable Genotoxins Targeted Against Prostate

National Research Council Canada - National Science Library

Essigmann, John

2001-01-01

.... We have used chemical synthetic methods to create bifunctional compounds consisting of a ligand for the androgen receptor linked to a reactive alkylating group that can produce covalent damage in cellular DNA...

Programmable Genotoxins Targeted Against Prostate Cancers

National Research Council Canada - National Science Library

Essigmann, John

1999-01-01

.... We have used chemical synthetic methods to create bifunctional compounds consisting of a ligands for the androgen receptor linked to a reactive alkylating group that can produce covalent damage in cellular DNA...

40 CFR 721.555 - Alkyl amino nitriles (generic).

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkyl amino nitriles (generic). 721... Substances § 721.555 Alkyl amino nitriles (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as alkyl amino nitriles (PMNs P-96...

The formation of quasi-alicyclic rings in alkyl-aromatic compounds

Science.gov (United States)

Straka, Pavel; Buryan, Petr; Bičáková, Olga

2018-02-01

The alkyl side chains of n-alkyl phenols, n-alkyl benzenes and n-alkyl naphthalenes are cyclised, as demonstrated by GC measurements, FTIR spectroscopy and molecular mechanics calculations. Cyclisation occurs due to the intramolecular interaction between an aromatic ring (-δ) and a hydrogen of the terminal methyl group (+δ) of an alkyl chain. In fact, conventional molecules are not aliphatic-aromatic, but quasi-alicyclic-aromatic. With the aromatic molecules formed with a quasi-alicyclic ring, the effect of van der Waals attractive forces increases not only intramolecularly but also intermolecularly. This effect is strong in molecules with propyl and higher alkyl substituents. The increase of intermolecular van der Waals attractive forces results in bi-linearity in the GC retention time of the compounds in question, observed in the dependence of the logarithm of the relative retention time on the number of carbons in a molecule in both polar and nonpolar stationary phases with both capillary and packed columns. The role of van der Waals forces has been demonstrated using the potential energies of covalent and noncovalent interactions for 2-n-alkyl phenols, n-alkyl benzenes and 1-n-alkyl- and 2-n-alkyl naphthalenes.

Over-additive increase of bacterial mutations by combined action of ultraviolet light and alkylation

International Nuclear Information System (INIS)

Herrmann, S.; Hotz, G.; Herrlich, P.

1982-05-01

Mutagenic agents added in combination may contribute to an overall biological effect in proportion to the effect they would have if given individually. The combined effect may, however, not just be additive but rather result in a response above or below expectation if the two mutagenic pathways interacted at some level. We report here on one such example. Ultraviolet light and subsequent treatment with the alkylating agent ethylmethane-sulfonate (EMS) led to an over-additive increase of bacterial mutations. This is interesting with respect to unravelling the level mutagens interact. In addition such data may relate to the human situation which is only in the process of being assessed. (orig.) [de

Glioblastoma and chemoresistance to alkylating agents: Involvement of apoptosis, autophagy, and unfolded protein response.

Science.gov (United States)

Hombach-Klonisch, Sabine; Mehrpour, Maryam; Shojaei, Shahla; Harlos, Craig; Pitz, Marshall; Hamai, Ahmed; Siemianowicz, Krzysztof; Likus, Wirginia; Wiechec, Emilia; Toyota, Brian D; Hoshyar, Reyhane; Seyfoori, Amir; Sepehri, Zahra; Ande, Sudharsana R; Khadem, Forough; Akbari, Mohsen; Gorman, Adrienne M; Samali, Afshin; Klonisch, Thomas; Ghavami, Saeid

2018-04-01

Despite advances in neurosurgical techniques and radio-/chemotherapy, the treatment of brain tumors remains a challenge. This is particularly true for the most frequent and fatal adult brain tumor, glioblastoma (GB). Upon diagnosis, the average survival time of GB patients remains only approximately 15months. The alkylating drug temozolomide (TMZ) is routinely used in brain tumor patients and induces apoptosis, autophagy and unfolded protein response (UPR). Here, we review these cellular mechanisms and their contributions to TMZ chemoresistance in brain tumors, with a particular emphasis on TMZ chemoresistance in glioma stem cells and GB. Copyright © 2017 Elsevier Inc. All rights reserved.

Structure-function relationship of substituted bromomethylcoumarins in nucleoside specificity of RNA alkylation.

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