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Chemistry & Biology Sep 2000Many conventional DNA alkylating anticancer drugs form adducts in the major groove of DNA. These are known to be chiefly repaired by both nucleotide (NER) and base (BER)...
BACKGROUND
Many conventional DNA alkylating anticancer drugs form adducts in the major groove of DNA. These are known to be chiefly repaired by both nucleotide (NER) and base (BER) excision repair in eukaryotic cells. Much less is known about the repair pathways acting on sequence specific minor groove purine adducts, which result from a promising new class of anti-tumour agents.
RESULTS
Benzoic acid mustards (BAMs) tethering 1-3 pyrrole units (compounds 1, 2 and 3) show increasing DNA sequence selectivity for alkylation from BAM and 1, alkylating primarily at guanine-N7 in the major groove, to 3 which is selective for alkylation in the minor groove at purine-N3 in the sequence 5'-TTTTGPu (Pu=guanine or adenine). This increasing sequence selectivity is reflected in increased toxicity in human cells. In the yeast Saccharomyces cerevisiae, the repair of untargeted DNA adducts produced by BAM, 1 and 2 depends upon both the NER and BER pathways. In contrast, the repair of the sequence specific minor groove adducts of 3 does not involve known BER or NER activities. In addition, neither recombination nor mismatch repair are involved. Two disruptants from the RAD6 mutagenesis defective epistasis group (rad6 and rad18), however, showed increased sensitivity to 3. In particular, the rad18 mutant was over three orders of magnitude more sensitive to 3 compared to its isogenic parent, and 3 was highly mutagenic in the absence of RAD18. Elimination of the sequence specific DNA adducts formed by 3 was observed in the wild type strain, but these lesions persisted in the rad18 mutant.
CONCLUSIONS
We have demonstrated that the repair of DNA adducts produced by the highly sequence specific minor groove alkylating agent 3 involves an error free adduct elimination pathway dependent on the Rad18 protein. This represents the first systematic analysis of the cellular pathways which modulate sensitivity to this new class of DNA sequence specific drugs, and indicates that the enhanced cytotoxicity of certain sequence specific minor groove adducts in DNA is the result of evasion of the common excision repair pathways.
Topics: Alkylating Agents; Alkylation; Base Pair Mismatch; Base Sequence; Benzoates; Canavanine; DNA Primers; DNA Repair; DNA, Fungal; Distamycins; Humans; Ligases; Mutagenicity Tests; Nitrogen Mustard Compounds; Nucleic Acid Conformation; Polymerase Chain Reaction; Recombination, Genetic; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Ubiquitin-Conjugating Enzymes
PubMed: 10980446
DOI: 10.1016/s1074-5521(00)00010-7 -
Chemico-biological Interactions May 1981In vivo alkylation of Yoshida sarcoma cell DNA by 3H-labelled 1,2:5,6-dianhydrogalactitol (DAG) yielded N-7 monogalactitylguanines and 1,6-di-(guanin-7-yl)-galactitol,...
In vivo alkylation of Yoshida sarcoma cell DNA by 3H-labelled 1,2:5,6-dianhydrogalactitol (DAG) yielded N-7 monogalactitylguanines and 1,6-di-(guanin-7-yl)-galactitol, similar to the alkylated products obtained by in vitro reaction of DNA with dianhydrogalactitol in neutral solution. The ratio between monoalkylguanines and diguaninyl product was 2-2.5, slightly increasing with doses. Persistence of alkylated products in DNA was followed in function of time. There was no significant loss of either monoalkylated bases or diguaninyl derivative during the observation period i.e. 7-24 h after treatment. In contrast, the physical measurements of the amount of renaturable DNA showed a rapid opening of cross-links in the same period. Taking the presence of diguaninyl moiety as an indicator of cross-links in DNA, these two latter findings show an apparent contradiction which could be reconciled however by the mechanism proposed by Reid and Walker (Biochim. Biophys. Acta, 179 (1969) 179) for the removal of cross-linkage induced by HN2. Accordingly, one arm of the cross-links is removed, probably enzymically, leaving the DNA non-renaturable, while the other arm of cross-link is still covalently attached to the DNA molecule rendering possible the detection of diguaninyl moiety in DNA at some later time. This concept for the removal of cross-links from DNA seems to be supported by our results too.
Topics: Alkylating Agents; Animals; Binding Sites; Cross-Linking Reagents; DNA; DNA, Neoplasm; Dianhydrogalactitol; Rats; Sarcoma, Yoshida; Sugar Alcohols
PubMed: 7214602
DOI: 10.1016/0009-2797(81)90144-7 -
Methods in Molecular Biology (Clifton,... 1997
Review
Topics: Alkylation; Antineoplastic Agents, Alkylating; Binding Sites; DNA; DNA Damage
PubMed: 9407533
DOI: 10.1385/0-89603-447-X:147 -
Chemical Research in Toxicology Oct 1998Bifunctional alkylating agents, such as those based on nitrogen mustard, form important parts of many anti-cancer chemotherapy protocols and are responsible for...
A monofunctional derivative of melphalan: preparation, DNA alkylation products, and determination of the specificity of monoclonal antibodies that recognize melphalan-DNA adducts.
Bifunctional alkylating agents, such as those based on nitrogen mustard, form important parts of many anti-cancer chemotherapy protocols and are responsible for increased incidences of secondary tumors in successfully treated patients. These drugs generally form a majority of monofunctional DNA adducts, although the bifunctional adducts appear to be necessary for their powerful cytotoxic and antitumor effects. The relative importance of bifunctional as opposed to monofunctional adducts in the varied biological consequences of drug exposure has not been studied in detail, particularly in relation to the role and specificity of biochemical responses to therapy-related DNA damage. A simple method is described for the preparation of useful quantities of a pure monofunctional derivative of the nitrogen mustard-based drug melphalan. Monohydroxymelphalan was prepared by partial hydrolysis, purified by reversed phase chromatography, and characterized by MS, NMR, and HPLC. Contamination with melphalan was =0.2%. The heat labile DNA base adducts formed by monohydroxymelphalan were shown to contain undetectable levels of cross-linked species. The ratio of adenine to guanine adducts was 0.62, similar to the equivalent ratio for melphalan. The sequence-dependent pattern of alkylation of purified DNA was indistinguishable from that of melphalan, but required a higher dose to achieve comparable extents of reaction. The specificities of two monoclonal antibodies that recognize melphalan-DNA adducts were investigated using DNA alkylated with [3H]monohydroxymelphalan. Adducts on this DNA showed similar immunoreactivities to adducts formed by melphalan. This shows clearly that neither antibody was specific for cross-linked adducts and that it is therefore possible to quantify adducts formed by both monohydroxymelphalan and melphalan with high sensitivities. The availability of monohydroxymelphalan in addition to melphalan, together with sensitive immunoassays for adducts on extracted DNA and in individual cells, constitutes a useful system for investigating cellular responses to the DNA modifications formed by a clinically relevant drug.
Topics: Alkylation; Antibodies, Monoclonal; Antibody Specificity; Antineoplastic Agents, Alkylating; DNA; DNA Adducts; Magnetic Resonance Spectroscopy; Mass Spectrometry; Melphalan
PubMed: 9778312
DOI: 10.1021/tx980129a -
Nucleic Acids Research Dec 1997We describe sequence-specific alkylation in the minor groove of double-stranded DNA by a hybridization-triggered reactive group conjugated to a triplex forming...
We describe sequence-specific alkylation in the minor groove of double-stranded DNA by a hybridization-triggered reactive group conjugated to a triplex forming oligodeoxyribonucleotide (TFO) that binds in the major groove. The 24 nt TFOs (G/A motif) were designed to form triplexes with a homopurine tract within a 65 bp target duplex. They were conjugated to an N 5-methyl-cyclopropapyrroloindole (MCPI) residue, a structural analog of cyclopropapyrroloindole (CPI), the reactive subunit of the potent antibiotic CC-1065. These moieties react in the DNA minor groove, alkylating adenines at their N3 position. In order to optimize alkylation efficiency, linkers between the TFO and the MCPI were varied both in length and composition. Quantitative alkylation of target DNA was achieved when the dihydropyrroloindole (DPI) subunit of CC-1065 was incorporated between an octa(propylene phosphate) linker and MCPI. The required long linker traversed one strand of the target duplex from the major groove-bound TFO to deliver the reactive group to the minor groove. Alkylation was directed by relative positioning of the TFOs. Sites in the minor groove within 4-8 nt from the end of the TFO bearing the reactive group were selectively alkylated.
Topics: Alkylating Agents; Alkylation; Cross-Linking Reagents; DNA; Duocarmycins; Indoles; Leucomycins; Nucleic Acid Conformation; Oligodeoxyribonucleotides
PubMed: 9396819
DOI: 10.1093/nar/25.24.5077 -
Carcinogenesis 1980The mechanism of induction of sister chromatid exchange (SCE) was investigated by treating Chinese hamster V-79 cells with two ethylating and two methylating mutagens at...
The mechanism of induction of sister chromatid exchange (SCE) was investigated by treating Chinese hamster V-79 cells with two ethylating and two methylating mutagens at doses, taken from linear response curves, that produced 30 SCE/cell. Concentrations of the DNA alkylation products were measured or calculated at 11 DNA base sites and at the phosphodiester bond. Ethyl methanesulfonate, N-methyl- and N-ethyl-N-nitrosourea produced comparable concentrations (3.3 to 3.5 micromol product/mol DNA phosphate) of O6-alkylguanine. Hence, alkylation at O6 of guanine appears relevant to SCE induction for these mutagens. Since alkylation at O6 of guanine has been positively correlated with mutagenesis in V-79 cells, these findings support the suggestion that SCE and mutagenesis can result from a common DNA lesion. Methyl methanesulfonate (MMS) produced very little O6-methylguanine, but did produce 3-methylthymine and 3-methyladenine, either of which might account for the MMS-induced SCE. Thus, for a series of mutagens, induction of SCE does not necessarily result from a single specific DNA lesion. Therefore, SCE can be considered a qualitative indicator of potential mutagenic events.
Topics: Alkylating Agents; Alkylation; Animals; Cell Line; Cricetinae; Cricetulus; DNA; DNA Methylation; Ethyl Methanesulfonate; Ethylnitrosourea; Methyl Methanesulfonate; Methylnitrosourea; Mutagens; Sister Chromatid Exchange
PubMed: 11219846
DOI: 10.1093/carcin/1.11.931 -
Current Medicinal Chemistry 2005Induced DNA interstrand cross-links by chemical agents or photoactivation play very important roles for cancer therapy. Several important clinical drugs (e.g. cisplatin,... (Review)
Review
Induced DNA interstrand cross-links by chemical agents or photoactivation play very important roles for cancer therapy. Several important clinical drugs (e.g. cisplatin, psoralens, and mitomycin C) are known to induce DNA ISC formation, which can disrupt cell maintenance and replication. Among these anti-tumor agents, one mechanism was involved in quinone methide intermediate. Quinone methide derivative has played important roles in organic syntheses as well as in chemical and biological processes. This review is concerned with current efforts of quinone methide derivatives to DNA alkylation and DNA cross-links. The latest advances in this field will be reviewed in this article. The chemical and physical properties of quinone methide derivatives, the interactions between nucleobases and quinone methide derivatives, the reactions with phosphodiester, DNA alkylation and cross-link via quinone methide intermediate action will be discussed.
Topics: Alkylating Agents; Alkylation; Cross-Linking Reagents; DNA; DNA Adducts; Humans; Indolequinones; Models, Chemical; Technology, Pharmaceutical
PubMed: 16305478
DOI: 10.2174/092986705774454724 -
Oligonucleotide-selenide conjugate: synthesis and its inducible sequence-specific alkylation of DNA.Bioorganic & Medicinal Chemistry Jun 2010Oligonucleotide-selenium conjugate was designed and synthesized and its sequence-specific cross-linking ability was investigated. The selenide derivatives can generate...
Oligonucleotide-selenium conjugate was designed and synthesized and its sequence-specific cross-linking ability was investigated. The selenide derivatives can generate covalent interstrand cross-linking with its complementary strand through the formation of o-QM intermediate induced by periodate oxidation. A cross-linking reaction yield of up to 50% was obtained. Hydroxyl radical footprinting experiment revealed that the quinone appendage specifically alkylated the cytosine base extending the duplex formed between the conjugate and the target strand.
Topics: Alkylating Agents; Alkylation; Base Sequence; Cross-Linking Reagents; Cytosine; DNA; Oligonucleotides; Selenium
PubMed: 20452775
DOI: 10.1016/j.bmc.2009.11.026 -
Bioscience Reports Sep 1984We have earlier reported that alkylation of DNA by the chemical carcinogen dimethyl sulphate, which mainly alkylates N-7 of guanine and N-3 of adenine, causes the... (Comparative Study)
Comparative Study
We have earlier reported that alkylation of DNA by the chemical carcinogen dimethyl sulphate, which mainly alkylates N-7 of guanine and N-3 of adenine, causes the formation of partially denatured regions in double-stranded DNA (Rizvi RY, Alvi NK & Hadi SM, Biosci. Rep. 2, 315-322, 1982). It is known that the major site of alkylation in DNA by N-ethyl-N-nitrosourea (EtNu) are the phosphate groups. N-methyl-N-nitrosourea (MeNu), on the other hand, causes the alkylation of mainly guanine residues. We have therefore studied the effect of these two alkylating carcinogens on the secondary structure of DNA. DNA alkylated with increasing concentrations of EtNu and MeNu was subjected to alkaline and S1 nuclease hydrolysis. Thermal melting profiles of alkylated DNA were also determined using S1 nuclease. The results indicated that alkylation by the two alkylating agents had a differential effect on the secondary structure of DNA. EtNu-alkylated DNA was found to be more thermostable than native DNA at neutral pH. It was however more alkali-labile than MeNu-alkylated DNA. The greater stability of EtNu-alkylated DNA was considered to be due to abolition of negative charges on phosphate alkylation.
Topics: Alkylation; Animals; Cattle; Chemical Phenomena; Chemistry; DNA; Ethylnitrosourea; Hydrolysis; Kinetics; Methylnitrosourea; Nitrosourea Compounds; Nucleic Acid Conformation; Nucleic Acid Denaturation; Thymus Gland
PubMed: 6509158
DOI: 10.1007/BF01128813 -
Nature Reviews. Cancer Mar 2002DNA is the molecular target for many of the drugs that are used in cancer therapeutics, and is viewed as a non-specific target of cytotoxic agents. Although this is true... (Review)
Review
DNA is the molecular target for many of the drugs that are used in cancer therapeutics, and is viewed as a non-specific target of cytotoxic agents. Although this is true for traditional chemotherapeutics, other agents that were discovered more recently have shown enhanced efficacy. Furthermore, a new generation of agents that target DNA-associated processes are anticipated to be far more specific and effective. How have these agents evolved, and what are their molecular targets?
Topics: Alkylation; Antineoplastic Agents; Antineoplastic Agents, Alkylating; Cross-Linking Reagents; DNA; DNA, Neoplasm; Humans; Neoplasms
PubMed: 11990855
DOI: 10.1038/nrc749