Effects of xenobiotics on CYP1 enzyme-mediated biotransformation and bioactivation of estradiol

Abstract

Endogenous estradiol (E2) exerts diverse physiological and pharmacological activities, commonly used for hormone replacement therapy. However, prolonged and excessive exposure to E2 potentially increases estrogenic cancer risk. Reportedly, CYP1 enzyme-mediated biotransformation of E2 is largely concerned with its balance between detoxification and carcinogenic pathways. Among the three key CYP1 enzymes (CYP1A1, CYP1A2, and CYP1B1), CYP1A1 and CYP1A2 mainly catalyze the formation of nontoxic 2-hydroxyestradiol (2-OH-E2), while CYP1B1 specifically catalyzes the formation of genotoxic 4-hydroxyestradiol (4-OH-E2). 4-OH-E2 can be further metabolized to electrophilic quinone intermediates accompanied by the generation of reactive oxygen species (ROS), triggering DNA damage. Since abnormal alterations in CYP1 activities can greatly affect the bioactivation process of E2, regulatory effects of xenobiotics on CYP1s are essential for E2-associated cancer development. To date, thousands of natural and synthetic compounds have been found to show potential inhibition and/or induction actions on the three CYP1 members. Generally, these chemicals share similar planar polycyclic skeletons, the structural motifs and substituent groups of which are important for their inhibitory/inductive efficiency and selectivity toward CYP1 enzymes. This review comprehensively summarizes these known inhibitors and/or inductors of E2-metabolizing CYP1s based on chemical categories and discusses their structure-activity relationships, which would contribute to better understanding of the correlation between xenobiotic-regulated CYP1 activities and estrogenic cancer susceptibility.

Keywords:

• Estradiol
• CYP1 enzymes
• biotransformation
• bioactivation
• structure–activity relationships
• enzymatic inhibition
• enzymatic induction

Author contributions

Xu Mao, Hui Li, and Jiang Zheng wrote and revised the manuscript. Xu Mao prepared tables and scheme. All of the authors have read and approved the final manuscript.

Additional information

Funding

This work was supported in part by the Natural Science Foundation of Heilongjiang Province of China under Grant [No. LH2022H101], Fundamental Scientific Research Fund for Higher Education Institutions of Heilongjiang Province of China under Grant [No. 2021-KYYWF-0467], and PhD Research Startup Foundation of Mudanjiang Medical University of Heilongjiang Province of China under Grant [No. 2021-MYBSKY-062].