Loss of NQO1 generates genotoxic estrogen byproducts and causes increased female susceptibility to UVA in Fuchs dystrophy

Abstract

Purpose : Purpose: Fuchs endothelial corneal dystrophy (FECD) is a genetic, female predominant, and late-stage oxidative disorder characterized by progressive loss of corneal endothelial cells (CEnCs). Previously, we have reported a decrease in [NAD(P)H: quinone oxidoreductase 1 (NQO1)], an estrogen metabolite detoxifying enzyme, and altered estrogen metabolism in FECD. In this study, we have investigated the role of reactive estrogen metabolites in the estrogen genotoxic pathway for FECD.

Methods : Methods: NQO1+/+ and NQO1-/- male and female mice were irradiated with UVA (500 J/cm²). CEnCs were imaged using a Heidelberg Retinal Imaging Rostock Corneal module (HRT-RCT) and quantified manually at weeks 1,2 and 4 post-UVA. At week 4 post-UVA, toxic estrogen metabolites (4-OHE_1/2 2-OHE_1/2), depurinating DNA adducts, and neutralized protective estrogen conjugates (4-OCH₃E_1/2 and 2-OCH₃E_1/2) were analyzed by Ultraperformance Liquid Chromatography/Tandem Mass Spectrometry (UPLC/MS) in the cornea and reactive oxygen species (ROS) was analyzed in the aqueous humor.

Results : Results: At week 2 post-UVA, when compared to the baseline, UVA irradiation led to the greatest decrease in HCEnCs in NQO1-/- female mice (45.7%), followed by NQO1-/- males (25%), NQO1+/+ females (24.8%) and then NQO+/+ males (6.8%). UPLC/MS-based metabolites analysis demonstrated that NQO1-/- females had a 4.2-fold increase (p<0.05) in the ratio (OD/OS) of 4-OHE_1/2, a 7.4-fold increase (p<0.05) in 2-OHE_1/2, a 10.1-fold increase (p<0.05) in 4-OHE_1/2 DNA adducts compared to NQO1-/- males, a 10-fold increase (p<0.05) in 2-OHE_1/2 for NQO1+/+ female compared to NQO1+/+ male. Thus, increased reactive estrogen adducts may lead to increased susceptibility to CEnC loss in NQO1-/- females. For 4-OCH₃E_1/2 and 2-OCH₃E_1/2, NQO1-/- females had a 5-fold and 2.7-fold decrease (p<0.05, respectively) compared to NQO-/- males, explaining the conversion of most estrogen metabolites to toxic byproducts in females. NQO1-/- females had a 3-fold increase in ROS compared to NQO1-/- males and unaltered in NQO1+/+ females and males.

Conclusions : Conclusions: Our study indicates that NQO1 deficiency accelerates UVA-induced CEnC loss in females due to increased reactive toxic estrogen DNA adducts. This novel study highlights the potential role of NQO1-mediated estrogen metabolite genotoxicity in explaining the higher incidence of FECD in females.

This is a 2021 ARVO Annual Meeting abstract.