The oxidative stress-triggered activation of the PKC-Nrf2-G6PD pathway drives Benz(a)pyrene-induced endometrial stromal cell proliferation.
Jiao Furong, Ma Mengwei, Peng Linglin, Luo Xinyan, Tong Mingjie, Yi Ting, Long Feng, Gao Rufei, Han Fei, He Junlin, Xu Hanting, Chen Xuemei
Abstract
Benzo(a)pyrene (BaP), a ubiquitous environmental pollutant, exerts reproductive toxicity by disrupting endometrial decidualization, yet the underlying mechanisms remain unclear. This study aimed to dissect the molecular cascade linking BaP-induced oxidative stress to abnormal endometrial stromal cell (ESC) proliferation and decidualization injury. Pregnant mice were gavaged with 0.2 mg kg-1·day-1 BaP from gestational Day 1 to 7, and primary ESCs were treated with BaP, H2O2, NAC and different inhibitor/agonist in vitro. BaP exposure reduced embryo implantation sites, induced asymmetric embryo distribution in bilateral uterine horns, and down-regulated decidualization markers (FOXO1, BMP2, HOXA10) in vivo and in vitro. Concurrently, BaP up-regulated proliferation markers (PHH3, PCNA, Ki67) and EdU incorporation in ESCs. Mechanistically, BaP induced uterine oxidative stress by down-regulating antioxidant enzymes (GPx4, CAT, SOD2) and accumulating intracellular ROS. H2O2 recapitulated BaP-induced phenotypes, while NAC reversed these effects. BaP-induced oxidative stress activated the PKCα/KEAP1 pathway, promoting Nrf2 phosphorylation and nuclear translocation. Inhibition of PKCα by PKC-IN-6 alleviated BaP-induced Nrf2 activation. Activated Nrf2 up-regulated transketolase (TKT) and glucose-6-phosphate dehydrogenase (G6PD), key enzymes of the pentose phosphate pathway (PPP), to drive abnormal ESC proliferation. ML385 inhibited Nrf2 to rescued BaP-induced ESC hyperproliferation and decidualization injury, while SFN activated Nrf2 mimicked BaP's toxic effects. Collectively, BaP induces oxidative stress in early pregnancy uteri, sequentially activating the PKCα/KEAP1/Nrf2 pathway and G6PD and TKT, leading to ESC proliferation-differentiation imbalance and decidualization impairment. This study uncovers a novel oxidative stress-mediated mechanism of BaP reproductive toxicity, identifying Nrf2 and PPP enzymes as potential therapeutic targets for pollutant-related pregnancy disorders.
Key Findings
- Benzo(a)pyrene (BaP) exposure induces oxidative stress in endometrial stromal cells (ESCs) by down-regulating antioxidant enzymes and increasing intracellular ROS.
- BaP activates the PKCα/KEAP1/Nrf2 pathway, leading to Nrf2 phosphorylation, nuclear translocation, and upregulation of pentose phosphate pathway enzymes G6PD and TKT.
- Activation of this pathway drives abnormal ESC proliferation and impairs decidualization, contributing to reproductive toxicity during early pregnancy.
Clinical Significance
This study identifies the PKCα/KEAP1/Nrf2 pathway and pentose phosphate pathway enzymes as potential therapeutic targets to mitigate BaP-induced oxidative stress and reproductive toxicity, offering new avenues for protecting pregnancy outcomes from environmental pollutants.
Citation
Jiao Furong, Ma Mengwei, Peng Linglinet al.. The oxidative stress-triggered activation of the PKC-Nrf2-G6PD pathway drives Benz(a)pyrene-induced endometrial stromal cell proliferation. Free radical biology & medicine. 2026-Apr-10.