Effects of reactive oxygen metabolites on erythropoietin production in renal carcinoma cells

Abstract

The present studies were undertaken to determine the effects of reactive oxygen metabolites on erythropoietin (Ep) biosynthesis in Ep-producing renal carcinoma (RC) cells using a sensitive radioimmunoassay for Ep. Xanthine (10 −5M) and increasing concentrations of xanthine oxidase (8 × 10 −7 to 5 × 10 −4 units/ml) produced a significant dose-related increase in Ep production at a concentration of ≥ 4 × 10 −6 units/ml, whereas xanthine alone had no effect. Catalase, a scavenger of hydrogen peroxide (H 2O 2), in concentrations of 50 to 500 μg/ml produced a significant inhibition of the increase in Ep production induced by xanthine-xanthine oxidase; while no effect was seen on basal levels of Ep production and the growth of RC cells. Glucose oxidase (≥ 0.032 mU/ml), a direct H 2O 2 generator, and exogenous H 2O 2 (≥ 4 × 10 −6M) added to the incubation mixture, caused a significant enhancement of Ep production in a dose-dependent manner. Xanthine-xanthine oxidase, glucose oxidase, and H 2O 2 in the above concentrations did not produce significant cytotoxicity ( 51Cr release or trypan blue dye exclusion). The present data suggests that H 2O 2, a reactive oxygen metabolite may play a significant role in Ep production.