Human cells enter mitosis with damaged DNA after treatment with pharmacological concentrations of genotoxic agents.
In the present paper, we report that mitosis is a key step in the cellular response to genotoxic agents in human cells. Cells with damaged DNA recruit γH2AX (phosphorylated histone H2AX), phosphorylate Chk1 (checkpoint kinase 1) and arrest in the G2-phase of the cell cycle. Strikingly, nearly all cells escape the DNA damage checkpoint and become rounded, by a mechanism that correlates with Chk1 dephosphorylation. The rounded cells are alive and in mitosis as measured by low phospho-Tyr(15) Cdk1 (cyclin-dependent kinase 1), high Cdk activity, active Plk1 (Polo-like kinase 1) and high phospho-histone H3 signals. This phenomenon is independent of the type of DNA damage, but is dependent on pharmacologically relevant doses of genotoxicity. Entry into mitosis is likely to be caused by checkpoint adaptation, and the HT-29 cell-based model provides a powerful experimental system in which to explore its molecular basis. We propose that mitosis with damaged DNA is a biologically significant event because it may cause genomic rearrangement in cells that survive genotoxic damage.
Cancer Cell Laboratory, Department of Biological Sciences, 4401 University Drive, University of Lethbridge, Lethbridge, AB, Canada, T1K 3M4.
Philip M
PM
Kubara
Sophie
S
Kernéis-Golsteyn
Aurélie
A
Studény
Brittany B
BB
Lanser
Laurent
L
Meijer
Roy M
RM
Golsteyn
D016203:CDC2 Protein Kinase / Q000378:metabolism; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism; D000071877:Checkpoint Kinase 1; D004247:DNA / Q000378:metabolism*; D004249:DNA Damage / Q000502:physiology; D016678:Genome; D019073:HT29 Cells; D006801:Humans; D008938:Mitosis; D009153:Mutagens / Q000009:adverse effects* / Q000494:pharmacology; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D000097869:Polo-Like Kinase 1
D016203:CDC2 Protein Kinase; D018797:Cell Cycle Proteins; D000071877:Checkpoint Kinase 1; D004247:DNA; D009153:Mutagens; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D000097869:Polo-Like Kinase 1; C000605867:CHEK1 protein, human