Aflatoxin B1-Induced COX-2 Expression Promotes Mitophagy and Contributes to Lipid Accumulation in Hepatocytes In Vitro and In Vivo

Abstract

Aim: Aflatoxin B1 (AFB1) is hepatotoxic. Numerous studies have shown that mitochondria play an essential role in AFB1-induced steatosis. However, the mechanisms of AFB1-induced steatosis via mitochondria are still obscure. The present study aimed to confirm that AFB1 causes hepatocyte steatosis regulated by cyclooxygenase-2 (COX-2)-induced mitophagy, both in vivo and in vitro. Methods: Adult male C57BL/6 mice were randomly divided into control group with the same volume of peanut oil and exposure group administered 0.6 mg/kg AFB1 once in 2 days for 1 month. HepG2 and Cas9-PTGS2 cells were treated with 5 μM AFB1 for 48 hours. Then, various indicators were evaluated. Results: Aflatoxin B1 causes liver injury and steatosis with increased alanine aminotransferase, aspartate aminotransferase, total cholesterol, total triglyceride levels in vivo and in vitro, and elevated lipid droplets in HepG2 cells. Cyclooxygenase-2 and mitophagy pathway were induced by AFB1 in both liver tissues and cultured HepG2 cells. Further studies have shown that knockout of COX-2 with the CRISPR/Cas9 system inhibited the AFB1-induced mitophagy and steatosis in HepG2 cells. Also, the inhibition of PTEN-induced putative kinase with RNA interference attenuated the AFB1-induced steatosis. Conclusions: The results of the current study suggested that AFB1 increases the expression of COX-2, which, in turn, elevates the level of mitophagy, thereby disrupting the normal mitochondrial lipid metabolism and causing steatosis. Thus, this study implies that COX-2 may be a potential target for therapy against AFB1-induced steatosis.

Contamination of Aflatoxins Induces Severe Hepatotoxicity Through Multiple Mechanisms

“…On basis of AFs-induced mitochondrial damage, for selective autophagy, mitophagy is the sequestration of damaged mitochondria by autophagosomes, which display loss of membrane potential. Both in vitro and in vivo studied indicate that AFB 1 promotes mitophagy by increased Parkin and PTEN-induced putative kinase 1 (PINK1) through inducing the expression of COX-2, then results in lipid accumulation and steatosis, due to the fact that mitophagy disrupts the normal mitochondrial lipid metabolism function ( Ren et al, 2020 ). But in consideration of positive role of mitophagy in removing damaged mitochondria and maintaining its quality and metabolism, more explicit evidences about AFs-induced mitophagy in hepatotoxicity need to be excavated.…”

Genome-Scale CRISPR Knockout Screening Identifies BACH1 as a Key Regulator of Aflatoxin B1-Induced Oxidative Damage

“…The results indicated that treatment with M2 reduces the formation of AFB 1 -DNA adducts and MDA in liver tissue, thus alleviating liver damage. AFB 1 is hepatotoxic and is a significant factor in promoting the development of primary hepatocellular carcinoma (HCC) [ 5 ]. Moreover, other studies reported that BACH1 is upregulated in HCC samples, with BACH1 facilitating the growth and metastasis of HCC [ 33 , 34 ].…”

“…The toxic effects of AFB 1 are both dose- and time-dependent, and aflatoxicosis can be either acute or chronic. Exposure to AFB 1 affects multiple organs like kidneys, liver, heart, testes, and ovaries, causing mutagenesis, growth retardation, and reproductive damage [ 5 , 6 ]. Moreover, AFB 1 toxicity significantly suppresses the immune system, increasing the risk of acquiring concurrent infectious diseases [ 7 ].…”

Aflatoxin B1 Toxicity and Protective Effects of Curcumin: Molecular Mechanisms and Clinical Implications

“…These data indicated that mitophagy may play a protective role during AFB1-exposure-induced adverse effects in animals or humans. Additionally, a previous study found that AFB1 exposure at a dose of 0.6 mg/kg for 28 days could significantly alter the expression of PINK1, Parkin, and COX-2, and the knockout of COX-2 significantly inhibited AFB1-induced mitophagy [ 159 ]. COX-2 also play critical roles in a variety of pathological processes, including cell proliferation, ferroptosis, inflammatory reaction, and apoptosis [ 159 ].…”