Human CYP1B1 enzyme-mediated, AhR enhanced activation of aflatoxin B1 for its genotoxicity in human cells. (15th January 2023)

• Record Type: Journal Article
• Authors: Chen, Yuting; Lu, Zhaohong; Li, Boxin; Wang, Huanhuan; Jiang, Tikeng; Xuan, Mei; Yang, Hui; Chen, Jialong; Liu, Xiaoshan; Liang, Hairong; Liu, Yungang; Tang, Huanwen
• Is Part Of: Toxicology letters. Volume 373(2023)
• Page Start: 132
• Page End: 140
• Publication Date: 2023-01-15
• Subjects: Aflatoxin B1 -- CYP1B1 -- Aryl hydrocarbon receptor -- Metabolism -- Micronuclei; Toxicology -- Periodicals; 363.179
• DOI: 10.1016/j.toxlet.2022.11.014
• Languages: English
• ISSNs: 0378-4274

Abstract

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. Graphical Abstract: ga1 Highlights: Human CYP1B1 activates aflatoxin B1 (AFB1) for potent DNA/chromosome damage. AFM1 is formed by AFB1 incubated with S9 fractions expressing human CYP1B1. Aryl hydrocarbon receptor mediates AFB1-induced nuclear translocation of CYP1B1.