Sequence selectivity of DNA covalent modification

Warpehoski, Martha A.; Hurley, Laurence H.

doi:10.1021/tx00006a001

Cited by 205 publications

(156 citation statements)

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“…The indole and benzofuran substituents of adozelesin (Fig. 1, subunits B and C, respectively) form non-covalent interactions with DNA that may contribute to the sequence preference of the drug (11,(17)(18)(19)(20)(21)(22). These non-covalent interactions cause bending and stiffening of the DNA helix (11-13).…”

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confidence: 99%

Inhibition of Initiation of Simian Virus 40 DNA Replication in Infected BSC-1 Cells by the DNA Alkylating Drug Adozelesin

Cobuzzi

Burhans

Beerman

1996

Journal of Biological Chemistry

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Adozelesin is a member of a family of extraordinarily cytotoxic DNA damaging agents that bind to the DNA minor groove in a sequence-specific manner and form covalent adducts with adenines. Previous studies employing purified enzymes and adozelesin-modified template DNAs suggested that adozelesin-DNA adducts inhibit DNA replication at the level of nascent DNA chain elongation. In this study, neutral/neutral two-dimensional agarose gel electrophoresis was employed to analyze simian virus 40 (SV40) DNA replication intermediates recovered from adozelesin-treated SV40 virusinfected cells. SV40 replication intermediates rapidly disappeared from infected cells when they were treated with adozelesin, but not when the cells were also treated with aphidicolin to block maturation of replicating SV40 DNA. We conclude that the disappearance of SV40 replication intermediates induced by adozelesin treatment was a consequence of maturation of these intermediates in the absence of new initiation events. Adozelesin inhibition of nascent chain elongation is first observed at concentrations above those needed to block initiation. Adozelesin treatment inhibits SV40 DNA replication at concentrations that produce adducts on just a small fraction of the intracellular population of SV40 DNA molecules.Adozelesin (U-73,975) is a synthetic analog of the antitumor antibiotic CC-1065 (1). The cytotoxic activity of adozelesin is orders of magnitude more potent than many common antineoplastic agents such as doxorubicin, cisplatin, 5-fluorouracil, or cytosine arabinoside (2-6). It is highly effective against a broad spectrum of murine tumors and human tumor xenografts without the lethal hepatotoxicity caused by CC-1065 (7). Adozelesin was chosen for clinical development based upon this in vivo potency and efficacy, and is currently undergoing phase II clinical evaluation (8).A primary intracellular target of adozelesin is DNA (3, 9). Like CC-1065, adozelesin elicits its potent cytotoxic and antitumor effects by alkylating DNA (10). As shown in Fig. 1, adozelesin is composed of three heterocyclic subunits linked serially by amide bonds. Similar to the parent compound, CC-1065, this structure conforms to the curved shape of DNA by mimicking the twist of the helix and allowing the drug to bind within the minor groove in a sequence-specific manner (11-16). The indole and benzofuran substituents of adozelesin (Fig. 1, subunits B and C, respectively) form non-covalent interactions with DNA that may contribute to the sequence preference of the drug (11,(17)(18)(19)(20)(21)(22). These non-covalent interactions cause bending and stiffening of the DNA helix (11-13). After binding to the minor groove, the cyclopropyl ring of the left-hand cyclopropylpyrroloindole substituent (Fig. 1) forms a covalent bond with N-3 of adenine at the 3Ј end of the binding site (23, 24). Two consensus sequences have been identified for this alkylation event: 5Ј-(A/T)(A/T)A* and 5Ј-(A/T)(G/C)(A/T)A*, where A* is the alkylated 3Ј adenine (9,22).Inhibition of DNA synthesis as ...

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confidence: 99%

Inhibition of Initiation of Simian Virus 40 DNA Replication in Infected BSC-1 Cells by the DNA Alkylating Drug Adozelesin

Cobuzzi

Burhans

Beerman

1996

Journal of Biological Chemistry

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“…The Psorospermin-DNA Adduct Induces Topoisomerase IImediated DNA Cleavage at Site B-In accordance with the instability of (N-7-guanine) DNA adducts (30), psorospermin-DNA adducts can undergo a slow depurination over several days at room temperature and neutral pH (3). Because it has been demonstrated that apurinic sites can stimulate topoisomerase II-mediated DNA cleavage when the lesions are located within the 4-base cleavage sites (21), the enhanced topoisomerase II-mediated DNA cleavage by psorospermin at cleavage site B could be produced either directly by the psorospermin-DNA adducts or indirectly by the depurination products, or both.…”

Section: Discussionmentioning

confidence: 99%

Topoisomerase II Site-directed Alkylation of DNA by Psorospermin and Its Effect on Topoisomerase II-mediated DNA Cleavage

Kwok¹,

Hurley²

1998

Journal of Biological Chemistry

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Psorospermin, a plant-derived antitumor agent, has been shown to selectively alkylate a guanine at the topoisomerase II cleavage site to trap the topoisomerase II-DNA cleaved complex. The results of this study provide further important insight into the mechanism of the topoisomerase II site-directed alkylation of DNA by psorospermin and its subsequent effects on the topoisomerase II-induced DNA cleavage. First, we demonstrate that the topoisomerase II-induced alkylation of DNA by psorospermin occurs at a time preceding the topoisomerase II-mediated strand cleavage event, because it occurs in the absence of Mg 2؉. We confirm that the alkylation of DNA by psorospermin takes place at N-7 of guanine in the presence of topoisomerase II, because substitution of the target guanine by 7-deazaguanine prevents alkylation. Because the stimulation of the topoisomerase II-induced DNA cleavage by psorospermin can be slowly reversed by the addition of excess salt, this indicates that alkylation of DNA by psorospermin traps a reversible topoisomerase II-DNA complex. Both the DNA alkylation by psorospermin in the presence of topoisomerase II and the enzyme-mediated DNA cleavage elevated by psorospermin are more enhanced at acidic pH values, in accordance with the increased stability of the topoisomerase II-DNA complex at acidic pH values. Finally, our results suggest that it is the psorospermin-DNA adducts, not the abasic sites resulting from depurination, that are responsible for the stimulation of the topoisomerase II-mediated cleavage. Because the precise location of the psorospermin within the topoisomerase II cleavage site is known, together with the covalent DNA linkage chemistry and the conformation of the psorospermin-DNA adduct, this structural insight provides an excellent opportunity for the design and synthesis of new, more effective topoisomerase II poisons.Psorospermin (Fig. 1), a natural product isolated from the roots and stem bark of the African plant Psorospermum febrifugum (1, 2), has been shown to intercalate into the DNA helix and to covalently modify guanine at the N-7 position in the major groove through an epoxide-mediated electrophilic attack (3). It is active against drug-resistant human leukemia lines and AIDS-related lymphoma. 1 In the initial mechanistic studies using recovered SV40 DNA from psorospermin-treated cells, it was found that numerous abasic sites were generated on the DNA. The extensive loss of DNA bases was proposed to lead to DNA strand breaks and protein-DNA cross-links, which might be responsible for the cytotoxicity and antitumor activity of this compound (5). Furthermore, although topoisomerase I and II can form cross-links to DNA in the presence of psorospermin, it was suggested that these cross-links are not specific (5). However, we have recently demonstrated that psorospermin alkylation at specific sites on DNA was greatly enhanced in the presence of topoisomerase II, 2 indicating that the antitumor activity of psorospermin might be related to its specific interaction with the t...

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Mechanistically, this selective DNA alkylation is achieved through the forced adoption of a helical conformation upon binding to the minor-groove AT-rich regions of DNA, which disrupts the stabilizing vinylogous amide and activates the cyclopropane for nucleophilic attack. 19,20 These natural products are not clinically viable due to either severe adverse events, including lethal hepatotoxicity and extreme myelotoxicity, or a lack of in vivo activity.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of a reductively activated duocarmycin prodrug against murine and human solid cancers

Vielhauer

Swink

Parelkar

et al. 2013

Cancer Biology & Therapy

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Sequence selectivity of DNA covalent modification

Cited by 205 publications

References 97 publications

Inhibition of Initiation of Simian Virus 40 DNA Replication in Infected BSC-1 Cells by the DNA Alkylating Drug Adozelesin

Inhibition of Initiation of Simian Virus 40 DNA Replication in Infected BSC-1 Cells by the DNA Alkylating Drug Adozelesin

Topoisomerase II Site-directed Alkylation of DNA by Psorospermin and Its Effect on Topoisomerase II-mediated DNA Cleavage

Evaluation of a reductively activated duocarmycin prodrug against murine and human solid cancers

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