title: Persistent p21 expression after Nutlin-3a removal is associated with senescence-like arrest in 4N cells.
abstract: Nutlin-3a is a preclinical drug that stabilizes p53 by blocking the interaction between p53 and MDM2. In our previous study, Nutlin-3a promoted a tetraploid G(1) arrest in two p53 wild-type cell lines (HCT116 and U2OS), and both cell lines underwent endoreduplication after Nutlin-3a removal. Endoreduplication gave rise to stable tetraploid clones resistant to therapy-induced apoptosis. Prior knowledge of whether cells are susceptible to Nutlin-induced endoreduplication and therapy resistance could help direct Nutlin-3a-based therapies. In the present study, Nutlin-3a promoted a tetraploid G(1) arrest in multiple p53 wild-type cell lines. However, some cell lines underwent endoreduplication to relatively high extents after Nutlin-3a removal whereas other cell lines did not. The resistance to endoreduplication observed in some cell lines was associated with a prolonged 4N arrest after Nutlin-3a removal. Knockdown of either p53 or p21 immediately after Nutlin-3a removal could drive endoreduplication in otherwise resistant 4N cells. Finally, 4N-arrested cells retained persistent p21 expression; expressed senescence-associated beta-galactosidase; displayed an enlarged, flattened phenotype; and underwent a proliferation block that lasted at least 2 weeks after Nutlin-3a removal. These findings demonstrate that transient Nutlin-3a treatment can promote an apparently permanent proliferative block in 4N cells of certain cell lines associated with persistent p21 expression and resistance to endoreduplication.
authors.affiliation: Department of Anatomy and Cell Biology, Rush University Medical Center, Chicago, Illinois 60612, USA.
authors.forename: Hong
authors.initials: H
authors.lastname: Shen
authors.forename: Carl G
authors.initials: CG
authors.lastname: Maki
mesh_terms: D002453:Cell Cycle / Q000187:drug effects*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D016922:Cellular Senescence / Q000187:drug effects*; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism*; D016193:G1 Phase / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D010879:Piperazines / Q000494:pharmacology*; D011123:Polyploidy; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D050759:Cyclin-Dependent Kinase Inhibitor p21; D007093:Imidazoles; D010879:Piperazines; D016159:Tumor Suppressor Protein p53; C482205:nutlin 3