title: Mechanism-based screen establishes signalling framework for DNA damage-associated G1 checkpoint response.
abstract: DNA damage activates checkpoint controls which block progression of cells through the division cycle. Several different checkpoints exist that control transit at different positions in the cell cycle. A role for checkpoint activation in providing resistance of cells to genotoxic anticancer therapy, including chemotherapy and ionizing radiation, is widely recognized. Although the core molecular functions that execute different damage activated checkpoints are known, the signals that control checkpoint activation are far from understood. We used a kinome-spanning RNA interference screen to delineate signalling required for radiation-mediated retinoblastoma protein activation, the recognized executor of G(1) checkpoint control. Our results corroborate the involvement of the p53 tumour suppressor (TP53) and its downstream targets p21(CIP1/WAF1) but infer lack of involvement of canonical double strand break (DSB) recognition known for its role in activating TP53 in damaged cells. Instead our results predict signalling involving the known TP53 phosphorylating kinase PRPK/TP53RK and the JNK/p38MAPK activating kinase STK4/MST1, both hitherto unrecognised for their contribution to DNA damage G1 checkpoint signalling. Our results further predict a network topology whereby induction of p21(CIP1/WAF1) is required but not sufficient to elicit checkpoint activation. Our experiments document a role of the kinases identified in radiation protection proposing their pharmacological inhibition as a potential strategy to increase radiation sensitivity in proliferating cancer cells.
authors.affiliation: Department of Cancer Biology, UCL Cancer Institute, London, United Kingdom.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Richardson
authors.forename: Simon R
authors.initials: SR
authors.lastname: Stockwell
authors.forename: He
authors.initials: H
authors.lastname: Li
authors.forename: Wynne
authors.initials: W
authors.lastname: Aherne
authors.forename: Maria Emanuela
authors.initials: ME
authors.lastname: Cuomo
authors.forename: Sibylle
authors.initials: S
authors.lastname: Mittnacht
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D002453:Cell Cycle; D045744:Cell Line, Tumor; D002470:Cell Survival; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D004249:DNA Damage; D016193:G1 Phase; D015972:Gene Expression Regulation, Neoplastic; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D048670:MAP Kinase Kinase 4 / Q000378:metabolism; D008957:Models, Genetic; D034622:RNA Interference; D015398:Signal Transduction; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D049452:Green Fluorescent Proteins; D048670:MAP Kinase Kinase 4