Production of large amounts of hydrogen peroxide by human tumor cells

TP Szatrowski, CF Nathan - Cancer research, 1991 - AACR
TP Szatrowski, CF Nathan
Cancer research, 1991AACR
Few nonphagocytic cells are known to generate reactive oxygen intermediates. Based on
horseradish peroxidase-dependent, catalase-inhibitable oxidation of fluorescent scopoletin,
seven human tumor cell lines constitutively elaborated H2O2 at rates (up to 0.5 nmol/104
cells/h) large enough that cumulative amounts at 4 h were comparable to the amount of
H2O2 produced by phorbol ester-triggered neutrophils. Superoxide dismutase-inhibitable
ferricytochrome c reduction was detectable at much lower rates. H2O2 production was …
Abstract
Few nonphagocytic cells are known to generate reactive oxygen intermediates. Based on horseradish peroxidase-dependent, catalase-inhibitable oxidation of fluorescent scopoletin, seven human tumor cell lines constitutively elaborated H2O2 at rates (up to 0.5 nmol/104 cells/h) large enough that cumulative amounts at 4 h were comparable to the amount of H2O2 produced by phorbol ester-triggered neutrophils. Superoxide dismutase-inhibitable ferricytochrome c reduction was detectable at much lower rates. H2O2 production was inhibited by diphenyleneiodonium, a flavoprotein binder (concentration producing 50% inhibition, 0.3 µm), and diethyldithiocarbamate, a divalent cation chelator (concentration producing 50% inhibition, 3 µm), but not by cyanide or azide, inhibitors of electron transport, or by agents that inhibit xanthine oxidase, polyamine oxidase, or cytochrome P450. Cytochrome b559, present in human phagocytes and lymphocytes, was undetectable in these tumor cells by a sensitive spectrophotometric method. Mouse fibroblasts transfected with human tyrosinase complementary DNA made melanin, but not H2O2. Constitutive generation of large amounts of reactive oxygen intermediates, if it occurs in vivo, might contribute to the ability of some tumors to mutate, inhibit antiproteases, injure local tissues, and therefore premote tumor heterogeneity, invasion, and metastasis.
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