Inhibition of human APE1 and MTH1 DNA repair proteins by dextran-coated γ-FeO ultrasmall superparamagnetic iron oxide nanoparticles.

To quantitatively evaluate the inhibition of human DNA repair proteins APE1 and MTH1 by dextran-coated γ-FeO ultrasmall superparamagnetic iron oxide nanoparticles (dUSPIONs). : Liquid chromatography-tandem mass spectrometry with isotope-dilution was used to measure the expression levels of APE1 and MTH1 in MCL-5 cells exposed to increasing doses of dUSPIONs. The expression levels of APE1 and MTH1 were measured in cytoplasmic and nuclear fractions of cell extracts. APE1 and MTH1 expression was significantly inhibited in both cell fractions at the highest dUSPION dose. The expression of MTH1 was linearly inhibited across the full dUSPION dose range in both fractions. These findings warrant further studies to characterize the capacity of dUSPIONs to inhibit other DNA repair proteins and .