title: The roles of p27(Kip1) and DNA damage signalling in the chemotherapy-induced delayed cell cycle checkpoint.
abstract: DNA lesions trigger the DNA damage response (DDR) machinery, which protects genomic integrity and sustains cellular survival. Increasing data underline the significance of the integrity of the DDR pathway in chemotherapy response. According to a recent work, persistent exposure of A549 lung carcinoma cells to doxorubicin induces an initial DDR-dependent checkpoint response, followed by a later DDR-independent, but p27(Kip1)-dependent one. Prompted by the above report and to better understand the involvement of the DDR signaling after chemotherapeutic stress, we examined the potential role of the canonical DDR pathway in A549 cells treated with doxorubicin. Exposure of A549 cells, prior to doxorubicin treatment, to ATM, ATR and DNA-PKcs inhibitors either alone or in various combinations, revealed that the earlier documented two-step response was DDR-dependent in both steps. Notably, inhibition of both ATM and ATR or selective inhibition of ATM or DNA-PKcs resulted in cell-cycle re-entry despite the increased levels of p27(Kip1) at all time points analyzed. We further investigated the regulation of p27(Kip1) protein levels in the particular setting. Our results showed that the protein status of p27(Kip1) is mainly determined by p38-MAPK, whereas the role of SKP2 is less significant in the doxoroubicin-treated A549 cells. Cumulatively, we provide evidence that the DNA damage signaling is responsible for the prolonged cell cycle arrest observed after persistent chemotherapy-induced genotoxic stress. In conclusion, precise identification of the molecular mechanisms that are activated during the chemotherapeutic cycles could potentially increase the sensitization to the therapy applied.
authors: Molecular Carcinogenesis Group, Laboratory of Histology-Embryology, School of Medicine University of Athens, Greece.
authors: Michalis
authors: M
authors: Liontos
authors: Molecular Carcinogenesis Group, Laboratory of Histology-Embryology, School of Medicine University of Athens, Greece.
authors: Georgia
authors: G
authors: Velimezi
authors: Molecular Carcinogenesis Group, Laboratory of Histology-Embryology, School of Medicine University of Athens, Greece.
authors: Ioannis S
authors: IS
authors: Pateras
authors: Molecular Carcinogenesis Group, Laboratory of Histology-Embryology, School of Medicine University of Athens, Greece.
authors: Roxani
authors: R
authors: Angelopoulou
authors: Department of Biological Chemistry, School of Medicine, University of Athens Athens, Greece.
authors: Athanasios G
authors: AG
authors: Papavassiliou
authors: Centre for Genotoxic Stress Research, Danish Cancer SocietyCopenhagen, Denmark; Laboratory of genome integrity, Institute of Molecular and Translational Medicine, Palacky UniverzityOlomouc, Czech Republic.
authors: Jiri
authors: J
authors: Bartek
authors: Molecular Carcinogenesis Group, Laboratory of Histology-Embryology, School of Medicine University of Athens, Greece.
authors: Vassilis G
authors: VG
authors: Gorgoulis
mesh_terms: D000072283:A549 Cells; D000970:Antineoplastic Agents / Q000494:pharmacology*; D064007:Ataxia Telangiectasia Mutated Proteins / Q000037:antagonists & inhibitors; D002110:Caffeine / Q000494:pharmacology; D002867:Chromones / Q000494:pharmacology; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000502:physiology*; D004249:DNA Damage; D051747:DNA-Activated Protein Kinase / Q000037:antagonists & inhibitors; D004317:Doxorubicin / Q000494:pharmacology*; D059565:G2 Phase Cell Cycle Checkpoints / Q000187:drug effects*; D006801:Humans; D009025:Morpholines / Q000494:pharmacology; D011753:Pyrones / Q000494:pharmacology; D044786:S-Phase Kinase-Associated Proteins / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: C495818:2-morpholin-4-yl-6-thianthren-1-yl-pyran-4-one; C499693:8-dibenzothiophen-4-yl-2-morpholin-4-yl-chromen-4-one; D000970:Antineoplastic Agents; C436291:CDKN1B protein, human; D002867:Chromones; D009025:Morpholines; D011753:Pyrones; D044786:S-Phase Kinase-Associated Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D002110:Caffeine; D004317:Doxorubicin; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D051747:DNA-Activated Protein Kinase; D048051:p38 Mitogen-Activated Protein Kinases