1. DNA damage causes TP53-dependent coupling of self-renewal and senescence pathways in embryonal carcinoma cells.
- Author
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Jackson TR, Salmina K, Huna A, Inashkina I, Jankevics E, Riekstina U, Kalnina Z, Ivanov A, Townsend PA, Cragg MS, and Erenpreisa J
- Subjects
- Antineoplastic Agents, Phytogenic pharmacology, Aurora Kinase B, Aurora Kinases, Autophagy, Cell Line, Tumor, Checkpoint Kinase 2, Cyclin-Dependent Kinase Inhibitor p16 biosynthesis, Cyclin-Dependent Kinase Inhibitor p21 biosynthesis, Cyclin-Dependent Kinase Inhibitor p21 genetics, Embryonal Carcinoma Stem Cells metabolism, Etoposide pharmacology, Female, G2 Phase Cell Cycle Checkpoints drug effects, Histones biosynthesis, Humans, Octamer Transcription Factor-3 biosynthesis, Octamer Transcription Factor-3 genetics, Ovarian Neoplasms, Phosphorylation, Protein Serine-Threonine Kinases biosynthesis, RNA Interference, RNA, Small Interfering, Rad51 Recombinase biosynthesis, Tumor Suppressor Protein p53 genetics, Up-Regulation, beta-Galactosidase biosynthesis, Cellular Senescence physiology, DNA Damage genetics, DNA Repair physiology, Tumor Suppressor Protein p53 metabolism
- Abstract
Recent studies have highlighted an apparently paradoxical link between self-renewal and senescence triggered by DNA damage in certain cell types. In addition, the finding that TP53 can suppress senescence has caused a re-evaluation of its functional role in regulating these outcomes. To investigate these phenomena and their relationship to pluripotency and senescence, we examined the response of the TP53-competent embryonal carcinoma (EC) cell line PA-1 to etoposide-induced DNA damage. Nuclear POU5F1/OCT4A and P21CIP1 were upregulated in the same cells following etoposide-induced G 2M arrest. However, while accumulating in the karyosol, the amount of OCT4A was reduced in the chromatin fraction. Phosphorylated CHK2 and RAD51/γH2AX-positive nuclear foci, overexpression of AURORA B kinase and moderate macroautophagy were evident. Upon release from G 2M arrest, cells with repaired DNA entered mitoses, while the cells with persisting DNA damage remained at this checkpoint or underwent mitotic slippage and gradually senesced. Reduction of TP53 using sh- or si-RNA prevented the upregulation of OCT4A and P21CIP1 and increased DNA damage. Subsequently, mitoses, micronucleation and senescence were all enhanced after TP53 reduction with senescence confirmed by upregulation of CDKN2A/P16INK4A and increased sa-β-galactosidase positivity. Those mitoses enhanced by TP53 silencing were shown to be multicentrosomal and multi-polar, containing fragmented and highly deranged chromosomes, indicating a loss of genome integrity. Together, these data suggest that TP53-dependent coupling of self-renewal and senescence pathways through the DNA damage checkpoint provides a mechanism for how embryonal stem cell-like EC cells safeguard DNA integrity, genome stability and ultimately the fidelity of self-renewal.
- Published
- 2013
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