| External factors: | Benzo[a]pyrene |
| Aging type: | Accelerate |
| Aging characteristic: |
| Category: | Chemical compounds |
| Phenotype: | Aging |
| Experiment: | SA-β-gal activity assay |
| Description: | To analyse whether B[a]P-induced proliferation arrest is associated with senescence, we measured the induction of senescence. Both microscopical detection of ?-Gal stained cells and flow cytometry-based detection of C12FDG-positive cells showed up to 40% senescent cells. Notably, 120 h (5 days) after B[a]P exposure seems to be an early stage in the development of the senescence phenotype, reaching 30–40% ?-Gal positivity. Already 7 days after B[a]P treatment, the amount of senescent MCF7 cells further increased up to ?80% (Figure ?(Figure7A,7A, left panel), whereas no signs of toxicity or alterations in the cell cycle distribution were observed. |
| Target gene: | P21 |
| R-EF-Target gene: | Upregulation |
| Official symbol(s): | P21 |
| Target gene experiment: | Western blot//RT-qPCR |
| Target gene description: | To analyse whether this repression is caused by the p21-DREAM pathway, B[a]P-induced transcriptional repression of E2F1 was analysed upon pharmacological inhibition of p21 and by siRNA-mediated knockdown. Both strategies efficiently rescued the expression of E2F1 mRNA. p21 inhibition also abolished E2F1 protein repression, further highlighting a critical role of p21. |
| Regulatory pathway: | E2F1 |
| R-EF-Pathway: | Downregulation |
| Pathway experiment: | RT-qPCR |
| Pathway description: | Repression of MSH2, MSH6, EXO1 and RAD51 as well as induction of p21 were still observed two weeks after B[a]P exposure, indicating that this feature is maintained in senescent cells. |
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