title: CDK4 inhibition restores G(1)-S arrest in MYCN-amplified neuroblastoma cells in the context of doxorubicin-induced DNA damage.
abstract: Relapse with drug-resistant disease is the main cause of death in MYCN-amplified neuroblastoma patients. MYCN-amplified neuroblastoma cells in vitro are characterized by a failure to arrest at the G(1)-S checkpoint after irradiation- or drug-induced DNA damage. We show that several MYCN-amplified cell lines harbor additional chromosomal aberrations targeting p53 and/or pRB pathway components, including CDK4/CCND1/MDM2 amplifications, p16INK4A/p14ARF deletions or TP53 mutations. Cells with these additional aberrations undergo significantly lower levels of cell death after doxorubicin treatment compared with MYCN-amplified cells, with no additional mutations in these pathways. In MYCN-amplified cells CDK4 expression is elevated, increasing the competition between CDK4 and CDK2 for binding p21. This results in insufficient p21 to inhibit CDK2, leading to high CDK4 and CDK2 kinase activity upon doxorubicin treatment. CDK4 inhibition by siRNAs, selective small compounds or p19(INK4D) overexpression partly restored G(1)-S arrest, delayed S-phase progression and reduced cell viability upon doxorubicin treatment. Our results suggest a specific function of p19(INK4D), but not p16(INK4A), in sensitizing MYCN-amplified cells with a functional p53 pathway to doxorubicin-induced cell death. In summary, the CDK4/cyclin D-pRB axis is altered in MYCN-amplified cells to evade a G(1)-S arrest after doxorubicin-induced DNA damage. Additional chromosomal aberrations affecting the p53-p21 and CDK4-pRB axes compound the effects of MYCN on the G(1) checkpoint and reduce sensitivity to cell death after doxorubicin treatment. CDK4 inhibition partly restores G(1)-S arrest and sensitizes cells to doxorubicin-mediated cell death in MYCN-amplified cells with an intact p53 pathway.
authors: Division of Tumor Genetics, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors: Sina
authors: S
authors: Gogolin
authors: Volker
authors: V
authors: Ehemann
authors: Gabriele
authors: G
authors: Becker
authors: Lena M
authors: LM
authors: Brueckner
authors: Daniel
authors: D
authors: Dreidax
authors: Steffen
authors: S
authors: Bannert
authors: Ingo
authors: I
authors: Nolte
authors: Larissa
authors: L
authors: Savelyeva
authors: Emma
authors: E
authors: Bell
authors: Frank
authors: F
authors: Westermann
mesh_terms: D017209:Apoptosis; D045744:Cell Line, Tumor; D002869:Chromosome Aberrations; D019938:Cyclin D1 / Q000378:metabolism; D051357:Cyclin-Dependent Kinase 2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D051358:Cyclin-Dependent Kinase 4 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D050764:Cyclin-Dependent Kinase Inhibitor p19 / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D004249:DNA Damage / Q000187:drug effects*; D004317:Doxorubicin / Q000633:toxicity*; D059585:G1 Phase Cell Cycle Checkpoints / Q000187:drug effects; D006801:Humans; D000071447:N-Myc Proto-Oncogene Protein; D009447:Neuroblastoma / Q000378:metabolism / Q000473:pathology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D015513:Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D016160:Retinoblastoma Protein / Q000378:metabolism; D059807:S Phase Cell Cycle Checkpoints / Q000187:drug effects; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism
chemical_list: D050764:Cyclin-Dependent Kinase Inhibitor p19; D050759:Cyclin-Dependent Kinase Inhibitor p21; C459801:MYCN protein, human; D000071447:N-Myc Proto-Oncogene Protein; D009687:Nuclear Proteins; D015513:Oncogene Proteins; D034741:RNA, Small Interfering; D016160:Retinoblastoma Protein; D016159:Tumor Suppressor Protein p53; D019938:Cyclin D1; D004317:Doxorubicin; D051357:Cyclin-Dependent Kinase 2; D051358:Cyclin-Dependent Kinase 4
keywords: RB1; TP53; apoptosis; cell cycle arrest; oncogene