2. Academic Validation
  3. Human CYP1B1 enzyme-mediated, AhR enhanced activation of aflatoxin B1 for its genotoxicity in human cells

Human CYP1B1 enzyme-mediated, AhR enhanced activation of aflatoxin B1 for its genotoxicity in human cells

  • Toxicol Lett. 2023 Jan 15:373:132-140. doi: 10.1016/j.toxlet.2022.11.014.
Yuting Chen 1,  Zhaohong Lu 2,  Boxin Li 2,  Huanhuan Wang 2,  Tikeng Jiang 2,  Mei Xuan 2,  Hui Yang 2,  Jialong Chen 2,  Xiaoshan Liu 2,  Hairong Liang 2,  Yungang Liu 3,  Huanwen Tang 4
Affiliations

Affiliations

  • 1 The First Dongguan Affiliated Hospital, Guangdong Medical University, Dongguan 523808, China; Dongguan Key Laboratory of Environmental Medicine, School of Public Health, Guangdong Medical University, Dongguan 523808, China.
  • 2 Dongguan Key Laboratory of Environmental Medicine, School of Public Health, Guangdong Medical University, Dongguan 523808, China.
  • 3 Department of Toxicology, School of Public Health (Guangdong Provincial Key Laboratory of Tropical Disease Research), Southern Medical University, Guangzhou 510515, China. Electronic address: yungliu@126.com.
  • 4 The First Dongguan Affiliated Hospital, Guangdong Medical University, Dongguan 523808, China; Dongguan Key Laboratory of Environmental Medicine, School of Public Health, Guangdong Medical University, Dongguan 523808, China. Electronic address: thw@gdmu.edu.cn.
PMID: 36442682 DOI: 10.1016/j.toxlet.2022.11.014
Abstract

Aflatoxin B1 (AFB1) is a human procarcinogen known to be activated by Cytochrome P450 (CYP) 1A2 and 3A4. In a previous study AFB1 caused chromosomal rearrangement in a yeast strain genetically engineered for stably expressing human CYP1B1. Yet, further verification of the effect of AFB1 in human cells, a potential role of the Aryl Hydrocarbon Receptor (AhR), and CYP1B1-catalyzed AFB1 metabolism remain unidentified. In this study, a human hepatocyte (L-02) line and a human lymphoblastoid (TK6) cell line were genetically engineered for the expression of human CYP1B1, producing L-02-hCYP1B1 and TK6-hCYP1B1, respectively. They were exposed to AFB1 and analyzed for the formation of micronucleus and elevation of γ-H2AX (indicating double-strand DNA breaks); the metabolites formed by CYP1B1 from AFB1 after incubation of AFB1 with human CYP1B1 isoenzyme microsomes were determined by LC-MS. The results showed significantly more potent induction of micronucleus by AFB1 in L-02-hCYP1B1 and TK6-hCYP1B1 than in the parental (L-02 and TK6) cells, and the effects were reduced by (E)- 2,3',4,5'-tetramethoxystilbene, a specific CYP1B1 inhibitor. In the AFB1- CYP1B1 microsomes incubations AFM1, a known stable metabolite of AFB1, was detected. Moreover, in L-02 and TK6 cells, AFB1 apparently increased the protein levels of AhR, ANRT and CYP1B1, and caused the nuclear translocation of AhR and ARNT, the latter effect being blocked by BAY-218 (an inhibitor of AhR). In conclusion, this study indicates that human CYP1B1 is capable of metabolically activating AFB1 through the AhR signaling pathway.

Keywords

Aflatoxin B1; Aryl hydrocarbon receptor; CYP1B1; Metabolism; Micronuclei.

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