Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

P53 plays a critical role in G1 checkpoint after DNA damage. MDM2 gene is a p53 target gene and its protein forms a feedback loop with p53 and inhibits p53-mediated G1 arrest. Sterigmatocystin (ST) is a mycotoxin and carcinogen. In this study we show that exposure of cells to ST for 12 or 24 h resulted in failure of G1 arrest at both time points. Accordingly, p53 protein was not increased and p21WAF1 expression was inhibited at 12 h, and both proteins were weakly induced at 24 h after treatment with ST. Meanwhile, MDM2 protein was induced in a p53-dependent fashion by ST at both 12 and 24 h. The induction of MDM2 was coincident with the cellular responses of p53 and p21WAF1, and might contribute to the failure of G1 arrest in ST-treated cells. In addition, ST-treated cells exhibited G2M arrest, regardless of p53 status. Our results indicate that the carcinogenic effects of ST seem to be mediated by failure of p53-mediated G1 checkpoint.
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PMID:Absence of p53-mediated G1 arrest with induction of MDM2 in sterigmatocystin-treated cells. 1099 85

It is considered that about sixty-five percent of people are suffering from Helicobacter pylori infection in our country. In the East Asian countries including Japan, such fungus as aspergillus are ubiquitously found in the environment as a contaminant in human food stuffs and animal feeds. Sterigmatocystin is a mycotoxin and a precursor of aflatoxin which is produced by Aspergillus versicolor. The mechanisms of gastric carcinoma development induced by the combination of Helicobacter pylori infection with Sterigmatocystin, a mycotoxin are shown and discussed. We revealed that Sterigmatocystin-treated cells exhibited an absence of P53-mediated G1 arrest with induction of MDM2 at 12 and 24 hours of treating time. Furthermore, it was revealed that long term treatment with Sterigmatocystin enhanced dominantly the development of intestinal metaplasia, and of precancerous lesions of gastric mucosa in Helicobacter pylori-infected Mongolian gerbils. It has been reported that the accumulations of P53 nucleotide substitutions in the H. pylori-infected monkeys were increased as the score of gastric atrophy increased, nevertheless no mutations were noted in the H. pylori-uninfected monkeys. The mechanisms of the development of gastric cancer produced by combination of H.P. with ST remain to be unclear. Further study concerning the mechanisms must be carried out.
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PMID:[The mechanisms of gastric cancer development produced by the combination of Helicobacter pylori with Sterigmatocystin, a mycotoxin]. 1528 59

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.
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PMID:Sterigmatocystin-induced DNA damage triggers G2 arrest via an ATM/p53-related pathway in human gastric epithelium GES-1 cells in vitro. 2370 30

Sterigmatocystin (ST), a mycotoxin commonly found in food and feed commodities, has been classified as a "possible human carcinogen." Our previous studies suggested that ST exposure might be a risk factor for esophageal cancer and that ST may induce DNA damage and G2 phase arrest in immortalized human esophageal epithelial cells (Het-1A). To further confirm and explore the cellular responses of ST in human esophageal epithelia, we comparatively evaluated DNA damage, cell cycle distribution and the relative mechanisms in primary cultured human esophageal epithelial cells (EPC), which represent a more representative model of the in vivo state, and Het-1A cells. In this study, we found that ST could induce DNA damage in both EPC and Het-1A cells but led to G1 phase arrest in EPC cells and G2 phase arrest in Het-1A cells. Furthermore, our results indicated that the activation of the ATM-Chk2 pathway was involved in ST-induced G1 phase arrest in EPC cells, whereas the p53-p21 pathway activation in ST-induced G2 phase arrest in Het-1A cells. Studies have demonstrated that SV40 large T-antigen (SV40LT) may disturb cell cycle progression by inactivating some of the proteins involved in the G1/S checkpoint. Het-1A is a non-cancerous epithelial cell line immortalized by SV40LT. To evaluate the possible perturbation effect of SV40LT on ST-induced cell cycle disturbance in Het-1A cells, we knocked down SV40LT of Het-1A cells with siRNA and found that under this condition, ST-induced G2 arrest was significantly attenuated, whereas the proportion of cells in the G1 phase was significantly increased. Furthermore, SV40LT-siRNA also inhibited the activation of the p53-p21 signaling pathway induced by ST. In conclusion, our data indicated that ST could induce DNA damage in both primary cultured and immortalized esophageal epithelial cells. In primary human esophageal epithelial cells, ST induced DNA damage and then triggered the ATM-Chk2 pathway, resulting in G1 phase arrest, whereas in SV40LT-immortalized human esophageal epithelial cells, SV40LT-mediated G1 checkpoint inactivation occurred, and ST-DNA damage activated p53-p21 signaling pathway, up-regulating G2/M phase regulatory proteins and finally leading to a G2 phase arrest. Thus, the SV40LT-mediated G1 checkpoint inactivation is responsible for the difference in the cell cycle arrest by ST between immortalized and primary cultured human esophageal epithelial cells.
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PMID:Sterigmatocystin induces G1 arrest in primary human esophageal epithelial cells but induces G2 arrest in immortalized cells: key mechanistic differences in these two models. 2529 23

Sterigmatocystin (ST), being a precursor of aflatoxin, is categorized as Group 2B carcinogen. Our previous studies found that both mismatch repair (MMR) pathways and p53 signaling pathway were involved in ST-induced G2 cell cycle arrest in human esophageal squamous epithelial cell line, HET-1A, in vitro. Studies showed that ERK, JNK and p38 signaling pathways played important roles in cell cycle arrest induced by several other carcinogens. However, the role of MAPK pathway and the links between the MMR and p53 signaling pathways in ST induced G2 phase arrest is still not clarified. In the present study, we first explored the role of MAPK pathway upon ST induced G2 arrest, and found that ST up-regulated the expression of G2/M regulatory factors through MAPK signaling pathway (both ERK and p38, but not JNK pathway). The inhibition of ERK and p38 significantly inhibited p53 activation by ST. Blockage of MMR pathway by silencing hMLH1 expression inhibited ERK, p38 and p53 activation and then attenuated G2 arrest by ST. Thus, in conclusion, the current study demonstrated that in response to ST induced DNA damage, hMLH1 was first activated, then triggered ERK, p38 and p53 activation and finally resulted in G2 arrest in HET-1A cells.
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PMID:The G2 phase arrest induced by sterigmatocystin is dependent on hMLH1- ERK/p38-p53 pathway in human esophageal epithelium cells in vitro. 2954 44