Calcium Indicator Dye Quin2 Inhibits Hydrogen Peroxide-Induced DNA Strand Break Formation via Chelation of Iron

Burkitt, Mark J.; Milne, Lesley; Tsang, Suk Ying; Tam, Shuk Ching

doi:10.1006/abbi.1994.1244

Cited by 17 publications

(17 citation statements)

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“…In view of the fact that ROS, particularly the hydroxyl free radical (dOH), can themselves bring about DNA fragmentation [15,16], relatively little attention appears to have been given to the possibility that the internucleosomal DNA fragmentation that is often observed in cells following exposure to ROS is caused, not by endonucleases (apoptosis), but by the hydroxyl radical [17,18]. With this in mind, we embarked upon a study of DNA fragmentation in HepG2 cells exposed to the copper(II) complex of 1,10-phenanthroline (o-phenanthroline, OP), Cu II (OP) # .…”

Section: Introductionmentioning

confidence: 99%

Research communication copper-1,10-phenanthroline induces internucleosomal DNA fragmentation in HepG2 cells, resulting from direct oxidation by the hydroxyl radical

Tsang

Tam

Bremner³

et al. 1996

Biochemical Journal

101

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In view of the current speculation regarding the possible role of reactive oxygen species (ROS) in apoptosis, both under physiological conditions and in response to chemicals that promote their intracellular formation, the present investigation was undertaken to examine whether DNA fragmentation during oxidative stress results from endonuclease activity (apoptosis) or from direct attack by ROS. We report that the incubation of HepG2 cells (a human-derived hepatoma cell line) with the copper(II) complex of 1,10-phenanthroline, CuII(OP)2, results in internucleosomal DNA fragmentation, which is widely recognized as being a hallmark of apoptosis. DNA fragmentation did not occur at low temperature, but activity was restored by the addition of ascorbic acid. It is proposed that DNA fragmentation results from the direct attack of hydroxyl radicals upon DNA. Hydroxyl radicals are produced from oxygen by the redox-cycling of CuII(OP)2, which is supported by metabolic processes at normal temperature. At low temperature ascorbic acid provides an artificial cellular reducing environment, thereby restoring hydroxyl radical formation. These findings were confirmed by the detection of internucleosomal DNA fragmentation following the exposure of isolated chromatin to a biomimetic CuII(OP)2 redox-cycling system. We conclude that DNA laddering, the widely employed hallmark of apoptosis, is not unique to endonuclease activity and may also result from direct attack upon DNA by the hydroxyl radical.

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Section: Introductionmentioning

confidence: 99%

Research communication copper-1,10-phenanthroline induces internucleosomal DNA fragmentation in HepG2 cells, resulting from direct oxidation by the hydroxyl radical

Tsang

Tam

Bremner³

et al. 1996

Biochemical Journal

101

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“…The possibility that quin 2 can act as an iron chelator has been considered, but contrarily to 1, 10-phenanthroline (9) and to desferral (11), the Fe-quin 2 complex does not prevent Femediated OH radical formation (19,27,42). Therefore, it was concluded that in Chinese hamster cells exposed to H202, quin 2 prevented nuclease Ca2+ activation and the consequent DNA ssb (26).…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, it was concluded that in Chinese hamster cells exposed to H202, quin 2 prevented nuclease Ca2+ activation and the consequent DNA ssb (26). Nevertheless, the use of quin 2 as a probe for participation of Ca2+ in DNA damage by oxidative species has been recently challenged based on two observations: (i) the Fe(iii)-quin 2 complex is not reduced by O2-and this might be required for OH radical formation (29); and (ii) quin 2 inhibits DNA oxidation by H202 in vitro, which was attributed to the removal ofDNA-bound iron by quin 2, causing in this manner a mitigation of site-specific Fenton reaction (19).…”

Section: Discussionmentioning

confidence: 99%

“…Copper is more active than iron as a Fenton reactant (12) but iron is much more abundant in biological systems (17). The consequence is that iron is usually the redox cation that participates preponderantly in cellular Fenton chemistry involving DNA (18,19).…”

Section: Oxidative Modificationsmentioning

confidence: 99%

“…This mechanism would be reminiscent of apoptosis (28); in most of the works in which it was investigated the supporting evidence came from the inhibition of strand break formation by quin 2, a calcium chelator. However, more recently the possibility was put forward that the iron chelator property of quin 2 was, in fact, responsible for the inhibitory effect (19,29).…”

Section: Oxidative Modificationsmentioning

confidence: 99%

See 2 more Smart Citations

DNA strand breaks produced by oxidative stress in mammalian cells exhibit 3′-phosphoglycolate termini

Bertoncini

Meneghini

1995

Nucl Acids Res

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In recent years two mechanisms have been proposed for the production of DNA strand breaks in cells undergoing oxidative stress: (i) DNA attack by OH radical, produced by Fenton reaction catalyzed by DNA-bound iron; and (ii) DNA attack by calcium-activated nucleases, due to the increase of cytosolic and nuclear calcium induced by oxidative stress. We set out to investigate the participation of the former mechanism by detecting and quantifying 3'-phosphoglycolate, a 3' DNA terminus known to be formed by OH radical attack to the deoxyribose moiety, followed by sugar ring rupture and DNA strand rupture. These structures were found in DNA of monkey kidney cells exposed to hydrogen peroxide, iron nitrilotriacetate or ascorbate, all species known to favor a cellular pro-oxidant status. The method employed to measure 3' phosphoglycolate was the 32P-postlabeling assay.

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N,N′-bis-(3,4,5-trimethoxybenzyl) ethylenediamine N,N′-diacetic acid as a new iron chelator with potential medicinal applications against oxidative stress

Galey

Dumats

Genard

et al. 1996

Biochemical Pharmacology

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Calcium Indicator Dye Quin2 Inhibits Hydrogen Peroxide-Induced DNA Strand Break Formation via Chelation of Iron

Cited by 17 publications

References 0 publications

Research communication copper-1,10-phenanthroline induces internucleosomal DNA fragmentation in HepG2 cells, resulting from direct oxidation by the hydroxyl radical

Research communication copper-1,10-phenanthroline induces internucleosomal DNA fragmentation in HepG2 cells, resulting from direct oxidation by the hydroxyl radical

DNA strand breaks produced by oxidative stress in mammalian cells exhibit 3′-phosphoglycolate termini

N,N′-bis-(3,4,5-trimethoxybenzyl) ethylenediamine N,N′-diacetic acid as a new iron chelator with potential medicinal applications against oxidative stress

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