Sterigmatocystin-Induced DNA Damage Triggers G2 Arrest via an ATM/p53-Related Pathway in Human Gastric Epithelium GES-1 Cells In Vitro

Abstract

Sterigmatocystin (ST), which is commonly detected in food and feed commodities, is a mutagenic and carcinogenic mycotoxin that has been recognized as a possible human carcinogen. Our previous study showed that ST can induce G2 phase arrest in GES-1 cells in vitro and that the MAPK and PI3K signaling pathways are involved in the ST-induced G2 arrest. It is now widely accepted that DNA damage plays a critical role in the regulation of cell cycle arrest and apoptosis. In response to DNA damage, a complex signaling network is activated in eukaryotic cells to trigger cell cycle arrest and facilitate DNA repair. To further explore the molecular mechanism through which ST induces G2 arrest, the current study was designed to precisely dissect the role of DNA damage and the DNA damage sensor ataxia telangiectasia-mutated (ATM)/p53-dependent pathway in the ST-induced G2 arrest in GES-1 cells. Using the comet assay, we determined that ST induces DNA damage, as evidenced by the formation of DNA comet tails, in GES-1 cells. We also found that ST induces the activation of ATM and its downstream molecules, Chk2 and p53, in GES-1 cells. The ATM pharmacological inhibitor caffeine was found to effectively inhibit the activation of the ATM-dependent pathways and to rescue the ST-induced G2 arrest in GES-1 cells, which indicating its ATM-dependent characteristic. Moreover, the silencing of the p53 expression with siRNA effectively attenuated the ST-induced G2 arrest in GES-1 cells. We also found that ST induces apoptosis in GES-1 cells. Thus, our results show that the ST-induced DNA damage activates the ATM/53-dependent signaling pathway, which contributes to the induction of G2 arrest in GES-1 cells.

Sterigmatocystin, 5-Methoxysterigmatocistin, and Their Combinations are Cytotoxic and Genotoxic to A549 and HepG2 Cells and Provoke Phosphorylation of Chk2, but not FANCD2 Checkpoint Proteins

“…Opposite to that, at relatively high concentrations (24 µM), both cell lines were blocked in the S and G2/M phase [ 14 ]. In human gastric epithelial GES-1 cells, exposure to 3 µM of STC for 24 h induced DNA damage, which subsequently activated ATM-Chk2 and ATM-p53 signalling pathways resulting in G2 arrest [ 38 ]. In the same cell line, exposure to 12 µM of STC for 24 h led to Chk1 activation and initial G2 arrest; however, 48 h treatment resulted in Chk1 inactivation, thus promoting checkpoint adaptation and entry of cells into mitosis despite DNA damage [ 38 , 39 ].…”

“…In human gastric epithelial GES-1 cells, exposure to 3 µM of STC for 24 h induced DNA damage, which subsequently activated ATM-Chk2 and ATM-p53 signalling pathways resulting in G2 arrest [ 38 ]. In the same cell line, exposure to 12 µM of STC for 24 h led to Chk1 activation and initial G2 arrest; however, 48 h treatment resulted in Chk1 inactivation, thus promoting checkpoint adaptation and entry of cells into mitosis despite DNA damage [ 38 , 39 ]. Such events may be responsible for STC-induced carcinogenesis upon prolonged exposure to its non-cytotoxic concentrations.…”

Genotoxic and mutagenic effects of mycotoxins: a review

“…chartarum S. typhimurium LT2 strains - (Ferguson et al, 1992) Mice Bone marrow +? (Munday, Pearson, & Ferguson, 1993) Chinese hamster AA48 + (Ferguson et al, 1992) Sheep Lymphocytes - (Ferguson et al, 1992) Stemphyltoxin (Krivobok et al, 1987;Sakai et al, 1992) S. typhimurium LT2 strains +,- (Wehner et al, 1978a;1978bMori et al, 1986;Wong et al, 1977) Human Hep3B,A549, Liver cells, GES-1 + + + (Anninou et al, 2014;Gao et al, 2015;Jakšić et al, 2012;Zhang et al, 2013) Chinese hamster V79 - (Fleck et al, 2016) Mice C3H,FM3A +? + (Umeda et al, 1977) Mice Bone marrow + (Curry, Reed, Martino, & Kitchin, 1984) Rat and Mice Hepatocyte + (Mori et al, 1984) T-2 toxins Trichothecenes F. sporotrichioides F. sulphureum S. typhimurium LT2 strains - (Wehner et al, 1978a;1978b) E. coli PQ37 strains - (Krivobok et al, 1987) Chinese hamster V79 cells +?…”

A Focus on Aflatoxin in Feedstuffs: New Developments in Analysis and Detection, Feed Composition Affecting Toxin Contamination, and Interdisciplinary Approaches to Mitigate It

“…This biosynthetic pathway is shared by norsolorinic acid, an anthraquinone, and sterigmatocystin (STE), a mutagenic and tumorigenic dihydrofuran toxin. STE is a late metabolite in the aflatoxin pathway and is also produced as a final biosynthetic product by some species such as Aspergillus, Aspergillus chevalieri, Aspergillus ruber, Aspergillus amstelodami, and Aspergillus aureolatus [2]. The reader is encouraged to consult the papers written by Bbosa and coworkers [3] and Dohnal and coworkers [4] that describe with detail aflatoxin metabolism.…”