title: A high-content cellular senescence screen identifies candidate tumor suppressors, including EPHA3.
abstract: Activation of a cellular senescence program is a common response to prolonged oncogene activation or tumor suppressor loss, providing a physiological mechanism for tumor suppression in premalignant cells. The link between senescence and tumor suppression supports the hypothesis that a loss-of-function screen measuring bona fide senescence marker activation should identify candidate tumor suppressors. Using a high-content siRNA screening assay for cell morphology and proliferation measures, we identify 12 senescence-regulating kinases and determine their senescence marker signatures, including elevation of senescence-associated β-galactosidase, DNA damage and p53 or p16 (INK4a)  expression. Consistent with our hypothesis, SNP array CGH data supports loss of gene copy number of five senescence-suppressing genes across multiple tumor samples. One such candidate is the EPHA3 receptor tyrosine kinase, a gene commonly mutated in human cancer. We demonstrate that selected intracellular EPHA3 tumor-associated point mutations decrease receptor expression level and/or receptor tyrosine kinase (RTK) activity. Our study therefore describes a new strategy to mine for novel candidate tumor suppressors and provides compelling evidence that EPHA3 mutations may promote tumorigenesis only when key senescence-inducing pathways have been inactivated.
authors: Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland.
authors: Jenni
authors: J
authors: Lahtela
authors: Laura B
authors: LB
authors: Corson
authors: Annabrita
authors: A
authors: Hemmes
authors: Matthew J
authors: MJ
authors: Brauer
authors: Sonja
authors: S
authors: Koopal
authors: James
authors: J
authors: Lee
authors: Thomas L
authors: TL
authors: Hunsaker
authors: Peter K
authors: PK
authors: Jackson
authors: Emmy W
authors: EW
authors: Verschuren
mesh_terms: D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D016922:Cellular Senescence / Q000235:genetics*; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D057166:High-Throughput Screening Assays; D006801:Humans; D008958:Models, Molecular; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D020641:Polymorphism, Single Nucleotide; D034741:RNA, Small Interfering / Q000235:genetics; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism; D036121:Receptor, EphA3; D015398:Signal Transduction; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D019941:Cyclin-Dependent Kinase Inhibitor p16; D034741:RNA, Small Interfering; D016159:Tumor Suppressor Protein p53; C491718:EPHA3 protein, human; D020794:Receptor Protein-Tyrosine Kinases; D036121:Receptor, EphA3; D001616:beta-Galactosidase
keywords: DDR; EPHA3/RTK; p16INK4a; p53; senescence; tumor suppressor