Peroxynitrite and 4-Hydroxynonenal Inactivate Breast Cancer Resistance Protein/ABCG2

Abstract

Oxidative stress may arise from a variety of pathologies and results in the formation of toxic and reactive chemical species. Extensive research has been done to establish mechanisms of formation and cytotoxic effects of a number of different products of oxidation stress including peroxynitrite (PN) and 4-hydroxynonenal (4HNE). However, relatively few studies have investigated their effects on ATP-binding cassette (ABC) transporters. The objective of this investigation was to determine the effects of PN and 4HNE on BCRP/ABCG2. To eliminate the effect of metabolic enzymes, the experiments were carried out with inside-out Sf9 membrane vesicles overexpressing BCRP/ABCG2 using riboflavin as a substrate. The experiments revealed that PN produced IC50 of about 31.2 ± 2.7 μM, based upon initial concentrations. The IC50 for 4HNE was estimated to be 92 ± 1.4 μM. Preincubation of membrane vesicles with either PN or 4HNE caused the maximal rate of transport (Vmax) to drop drastically, up to 19 times, with no or much smaller effect on Km. Thus, PN and 4NE can inhibit BCRP transport activity.

Metabolomic Profiling and Drug Interaction Characterization Reveal Riboflavin As a Breast Cancer Resistance Protein–Specific Endogenous Biomarker That Demonstrates Prediction of Transporter Activity In Vivo

“…In agreement, riboflavin was reported previously as a substrate in vitro of murine, bovine, and human BCRP using cells and membrane vesicles overexpressing this transporter (van Herwaarden et al, 2007, Otero et al, 2016, Verenich and Gerk, 2019, Ganguly et al, 2021. Thirdly, in line with the significant effect of BCRP deficiency on riboflavin disposition in mice and its substrate potential towards BCRP in vitro, chemical inhibitors of BCRP 2 and 3), and are well below the K m value for hBCRPmediated riboflavin transport (296 ± 71 µM) (Verenich and Gerk, 2019). Therefore, saturation of BCRP transporters is unlikely at the riboflavin concentrations observed in our preclinical drug inhibition studies.…”

“…In contrast, no differences in the transport of riboflavin were observed with cP-gp or hP-gp membrane vesicles compared with the control membrane vesicles (Figure 5B). In agreement, riboflavin was reported previously as a substrate in vitro of murine, bovine, and human BCRP using cells and membrane vesicles overexpressing this transporter (van Herwaarden et al, 2007, Otero et al, 2016, Verenich and Gerk, 2019, Ganguly et al, 2021. Thirdly, in line with the significant effect of BCRP deficiency on riboflavin disposition in mice and its substrate potential towards BCRP in vitro, chemical inhibitors of BCRP 2 and 3), and are well below the K m value for hBCRPmediated riboflavin transport (296 ± 71 µM) (Verenich and Gerk, 2019).…”