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ChemMedChem Oct 2023Three compounds with arylboronate esters conjugated with two equivalent nitrogen mustards [bis(2-chloroethyl)methylamine, HN2] have been synthesized and characterized....
Three compounds with arylboronate esters conjugated with two equivalent nitrogen mustards [bis(2-chloroethyl)methylamine, HN2] have been synthesized and characterized. These inactive small molecules selectively react with H O to produce multiple DNA cross-linkers, such as two HN2 molecules alongside a bisquinone methide (bisQM), leading to efficient DNA ICL formation. In comparison to other amine functional groups, using HN2 as a leaving group greatly improves the DNA cross-linking efficiency of these arylboronate esters as well as cellular activity. The introduction of HN2 in these arylboronate ester analogues favored the generation of bisQM that can directly cross-link DNA. Two equivalents of HN2 are also generated from these compounds upon treatment with H O , which directly produces DNA ICL products. The cumulative effects of HN2 and bisQM on DNA cross-linking makes these molecules highly effective H O -inducible DNA ICL agents. The three compounds with HN2 as a leaving group showed greatly enhanced cytotoxicity towards cancer cells in comparison to those containing trimethyl amine as a leaving group. This provides an effective strategy for further design of novel potential ROS-activated anticancer prodrugs.
Topics: Alkylating Agents; Prodrugs; Nitrogen Mustard Compounds; DNA; Amines; Cross-Linking Reagents
PubMed: 37440359
DOI: 10.1002/cmdc.202300273 -
Biochimica Et Biophysica Acta. General... Feb 2017Alkylated DNA-protein alkyltransferases (AGTs) are conserved proteins that repair alkylation damage in DNA by using a single-step mechanism leading to irreversible...
BACKGROUND
Alkylated DNA-protein alkyltransferases (AGTs) are conserved proteins that repair alkylation damage in DNA by using a single-step mechanism leading to irreversible alkylation of the catalytic cysteine in the active site. Trans-alkylation induces inactivation and destabilization of the protein, both in vitro and in vivo, likely triggering conformational changes. A complete picture of structural rearrangements occurring during the reaction cycle is missing, despite considerable interest raised by the peculiarity of AGT reaction, and the contribution of a functional AGT in limiting the efficacy of chemotherapy with alkylating drugs.
METHODS
As a model for AGTs we have used a thermostable ortholog from the archaeon Sulfolobus solfataricus (SsOGT), performing biochemical, structural, molecular dynamics and in silico analysis of ligand-free, DNA-bound and mutated versions of the protein.
RESULTS
Conformational changes occurring during lesion recognition and after the reaction, allowed us to identify a novel interaction network contributing to SsOGT stability, which is perturbed when a bulky adduct between the catalytic cysteine and the alkyl group is formed, a mandatory step toward the permanent protein alkylation.
CONCLUSIONS
Our data highlighted conformational changes and perturbation of intramolecular interaction occurring during lesion recognition and catalysis, confirming our previous hypothesis that coordination between the N- and C-terminal domains of SsOGT is important for protein activity and stability.
GENERAL SIGNIFICANCE
A general model of structural rearrangements occurring during the reaction cycle of AGTs is proposed. If confirmed, this model might be a starting point to design strategies to modulate AGT activity in therapeutic settings.
Topics: Alkyl and Aryl Transferases; Alkylating Agents; Alkylation; Catalysis; DNA; DNA Repair; DNA-Binding Proteins; Protein Domains; Protein Stability; Sulfolobus solfataricus
PubMed: 27777086
DOI: 10.1016/j.bbagen.2016.10.020 -
Journal of Cellular Biochemistry Feb 2004The targeting of damage to DNA remains an attractive strategy to kill tumor cells. One of the serious side effects of alkylating agents is that they create both toxic... (Review)
Review
The targeting of damage to DNA remains an attractive strategy to kill tumor cells. One of the serious side effects of alkylating agents is that they create both toxic (desired) and mutagenic (undesired) lesions. The result is that patients successfully treated for a primary cancer are at significant risk to develop cancer related to their therapy. To address this issue we have prepared agents that selectively methylate DNA at the N3-position of adenine. The presence of this lesion in DNA is thought to halt DNA polymerase, and this then initiates a cascade of events including cell death. The toxicity and mutagenicity of the compound, Me-lex, used to generate N3-methyladenine is discussed in bacterial, yeast, and mammalian systems. Mechanisms are proposed to explain the biological activities of N3-methyladenine.
Topics: Adenine; Alkylating Agents; Alkylation; Animals; Base Sequence; DNA Damage; DNA Methylation; Escherichia coli; Methyl Methanesulfonate; Mice; Models, Chemical; Molecular Sequence Data; Mutagenesis; Mutation; Netropsin; Saccharomyces cerevisiae
PubMed: 14743385
DOI: 10.1002/jcb.10698 -
Mutagenesis Nov 2002Alkylating agents are a structurally diverse group of compounds that cause a wide range of biological effects, including cell death, mutation and cancer. DNA damaged by... (Review)
Review
Alkylating agents are a structurally diverse group of compounds that cause a wide range of biological effects, including cell death, mutation and cancer. DNA damaged by these agents contains widely different amounts of 12 alkylated purines/pyrimidines and two phosphotriester isomers. The biological effects appear to be mediated predominantly by attack at the O(6) position of guanine. DNA extracted from various normal human tissues contains detectable levels of O(6)-alkylguanine, the source of which has not been defined. Given that, following DNA replication, this lesion cannot only generate point mutations but can also initiate mismatch repair-mediated DNA recombination and cell death, it seems worthwhile to consider the possible contribution of these events and cell killing to the aetiology of human cancer. There is increasing evidence that point mutations are not the only mechanism involved in malignant transformation by alkylating agents. Some cancer chemotherapeutic agents exploit the cytotoxic effects of O(6)-alkylguanine and an understanding of the processing of this lesion has allowed strategies to be developed that should increase the effectiveness of such agents.
Topics: Alkylating Agents; Animals; DNA; DNA Adducts; DNA Damage; DNA Methylation; Guanine; Humans; Neoplasms; Point Mutation; Recombination, Genetic
PubMed: 12435845
DOI: 10.1093/mutage/17.6.483 -
Journal of Molecular Biology Jul 2000Duocarmycin SA is a member of a growing class of interesting lead compounds for chemotherapy, distinguished by the manner in which they bind to and react with DNA...
Duocarmycin SA is a member of a growing class of interesting lead compounds for chemotherapy, distinguished by the manner in which they bind to and react with DNA substrates. The first three-dimensional structure of a DNA adduct of an unnatural enantiomer from this family has been determined by (1)H NMR methods. Comparison to the previously determined structure of the natural enantiomer bound in the same DNA-binding site provides unique insights into the similarities and critical distinctions producing the respective alkylation products and site selectivities. The results also support the hypothesis that the duocarmycin SA alkylation reaction is catalyzed by the binding to DNA, and provide a deeper understanding of the structural basis for this unique mode of activation.
Topics: Alkylating Agents; Alkylation; Antibiotics, Antineoplastic; Base Sequence; Binding Sites; DNA Adducts; Duocarmycins; Indoles; Kinetics; Models, Molecular; Molecular Conformation; Nuclear Magnetic Resonance, Biomolecular; Oligodeoxyribonucleotides; Pyrroles; Stereoisomerism; Structure-Activity Relationship; Thermodynamics
PubMed: 10903864
DOI: 10.1006/jmbi.2000.3887 -
Acta Pharmacologica Et Toxicologica 1981Methods for the detection of in vivo alkylation of nucleic acids are discussed. Alkylation of mammalian DNA at N-7 of guanine provides the most sensitive and least...
Methods for the detection of in vivo alkylation of nucleic acids are discussed. Alkylation of mammalian DNA at N-7 of guanine provides the most sensitive and least equivocal evidence of methylation by an exogenous chemical or its metabolite. No 7-methylguanine was detected in the combined DNA from the lungs, livers, hearts, brains, kidneys, testes and spleens from 20 rats exposed to 0.064 micrograms l-1 of [Me-14C]-dichlorvos at a specific radioactivity of 113 Ci mol-1 for 12 hrs.
Topics: Alkylating Agents; Animals; DNA; Dichlorvos; Guanine; Insecticides; Methylation; Rats
PubMed: 7344411
DOI: No ID Found -
Chemical Reviews Jul 2002
Review
Topics: Animals; Antibiotics, Antineoplastic; Antineoplastic Agents, Alkylating; DNA Methylation; DNA, Neoplasm; Duocarmycins; Humans; Indoles; Leucomycins; Nucleic Acid Conformation; Pyrrolidinones
PubMed: 12105933
DOI: 10.1021/cr010046q -
Proceedings of the National Academy of... Dec 1995This report presents evidence that a reduced pyrrolo[1,2-a]benzimidazole (PBI) cleaves DNA as a result of phosphate alkylation followed by hydrolysis of the resulting...
Evidence for DNA phosphate backbone alkylation and cleavage by pyrrolo[1,2-a]benzimidazoles: small molecules capable of causing base-pair-specific phosphodiester bond hydrolysis.
This report presents evidence that a reduced pyrrolo[1,2-a]benzimidazole (PBI) cleaves DNA as a result of phosphate alkylation followed by hydrolysis of the resulting phosphate triester. The base-pair specificity of the phosphate alkylation results from Hoogsteen-type hydrogen bonding of the reduced PBI in the major groove at only A.T and G.C base pairs. Alkylated phosphates were detected by 31P NMR and the cleavage products were detected by 1H NMR and HPLC. Evidence is also presented that a reduced PBI interacts with DNA in the major groove rather than in the minor groove or by intercalation.
Topics: Alkylating Agents; Alkylation; Benzimidazoles; Chromatography, High Pressure Liquid; DNA; DNA Damage; Hydrogen Bonding; Magnetic Resonance Spectroscopy; Models, Chemical; Organophosphates; Pyrroles
PubMed: 8524862
DOI: 10.1073/pnas.92.25.11854 -
Biochemistry Oct 1990The sequence preferences for alkylation of a series of novel parasubstituted aniline mustards linked to the DNA-intercalating chromophore 9-aminoacridine by an alkyl... (Comparative Study)
Comparative Study
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.
Topics: Alkylating Agents; Alkylation; Aniline Mustard; Antineoplastic Agents; Base Sequence; Cross-Linking Reagents; DNA; Intercalating Agents; Molecular Sequence Data; Mustard Compounds; Nucleic Acid Conformation; Structure-Activity Relationship
PubMed: 2271617
DOI: 10.1021/bi00494a007 -
Mutation Research May 1994Alkylating agents produce a spectrum of DNA lesions alkylated at different sites on the molecule. These lesions differ in their propensities to cause effects such as...
Alkylating agents produce a spectrum of DNA lesions alkylated at different sites on the molecule. These lesions differ in their propensities to cause effects such as cytotoxicity, mutations and sister-chromatid exchanges. We have used our observations that some methylating agents produce increasing levels of chromosome aberrations (abs) through successive cell cycles in Chinese hamster ovary cells, but not in normal human cells, to begin a study of which alkylated products are most likely to lead to chromosome abs, and in particular which adducts persist in DNA and cause abs after the first cell cycle. We previously observed increasing yields of abs with successive cell cycles in CHO-WBL cells treated with dimethyl nitrosamine (DMN), e.g., at 10 mM DMN, 8.8% cells with abs at first metaphase (M1) and 26.0% at third metaphase (M3) after treatment. Here we tested 4 methylating agents and their ethyl analogs in CHO cells, normal human fibroblasts (L136), and human lymphocytes. We sampled cells at several times after treating for 3 h (CHO and lymphocytes) or 4.5 h (L136). S9 metabolic activation was used for DMN and diethyl nitrosamine. BrdUrd labeling was used to identify cells in M1, M2 and M3. The methylating agents were more potent aberration (ab) inducers than ethylating agents, on a molar basis. In CHO cells, yields of abs were maintained or increased through up to 3 cell cycles after treatment with DMN, methyl methanesulfonate, methyl nitrosourea and 1-methyl-3-nitro-1-nitrosoguanidine (MNNG). With ethylating agents the ab yields in CHO cells were similar or lower in second and third cycles. In contrast, there was no evidence for persistence of lesions leading to abs in either human cell type; ab yields were markedly decreased with subsequent cell cycles for all agents. Normal human cells are proficient in repair of alkylation at the O6 site of guanine by O6-alkylguanine-DNA alkyltransferase (AGT), whereas CHO cells lack AGT activity. To explore the role of repair by AGT on the lesions involved in production of abs, we studied L136 cells, with and without O6-benzylguanine (BZG), a specific inhibitor of AGT. With MNNG, inhibition of AGT resulted in higher ab yield and production of abs through later cell cycles, so that human fibroblasts now behaved similarly to CHO cells. Preliminary data from the reciprocal experiment in CHO cells engineered to express high levels of AGT revealed a greatly decreased ab response to MNNG. In addition, the low ab yields observed were similar through later cycles or increased only slightly.(ABSTRACT TRUNCATED AT 400 WORDS)
Topics: Alkylating Agents; Alkylation; Animals; CHO Cells; Cells, Cultured; Chromosome Aberrations; Cricetinae; DNA; DNA Damage; Fibroblasts; Humans; Lymphocytes; Male; Methyltransferases; O(6)-Methylguanine-DNA Methyltransferase
PubMed: 7513826
DOI: 10.1016/0027-5107(94)90279-8