Lifespan of etoposide-treated human neutrophils is affected by antioxidant ability of quercetin.
Toxicol In Vitro
; 21(6): 1020-30, 2007 Sep.
Article
em En
| MEDLINE
| ID: mdl-17467952
ABSTRACT
Neutropenia is the primary dose-limiting effect of etoposide toxicity resulting in a decreased efficiency of cancer treatment. Hence, the protection of neutrophils has important clinical implications. We investigated whether quercetin, due to its antioxidant properties, is able to modulate the damaging activity of etoposide. DNA damage, evaluated by the comet assay, and apoptosis, determined by FACScan flow cytometry using Annexin/PI, increased with etoposide doses. The intracellular level of reactive oxygen species (ROS) was enhanced in resting neutrophils incubated with etoposide at concentrations up to 25 microM; above this concentration etoposide revealed antioxidant properties. Only in latex-activated neutrophils, i.e. with latex-stimulated respiratory burst was the ROS production inhibited, as assessed by the luminol amplified chemiluminescence. The characteristic electron spin resonance (ESR) signal of etoposide phenoxyl radical, which occurs in the presence of myeloperoxidase, H2O2 and etoposide, was quenched by quercetin in a dose-dependent manner (0.1-0.5 microM). Quercetin also inhibited DNA damage induced by etoposide and enhanced the inhibitory action of etoposide on the ROS formation in neutrophils. However, quercetin (1 microM) lowered early and late apoptosis/necrosis only when apoptosis was induced by 25 microM etoposide; at higher etoposide concentration apoptosis was enhanced. Summing up, antioxidant adjuvant therapy using quercetin can be beneficial in prolonging neutrophils' lifespan in peripheral blood only when etoposide plasma concentration is low.
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Base de dados:
MEDLINE
Assunto principal:
Quercetina
/
Etoposídeo
/
Neutrófilos
/
Antineoplásicos Fitogênicos
/
Antioxidantes
Limite:
Humans
Idioma:
En
Revista:
Toxicol In Vitro
Assunto da revista:
TOXICOLOGIA
Ano de publicação:
2007
Tipo de documento:
Article
País de afiliação:
Polônia