title: Mechanism-based screen for G1/S checkpoint activators identifies a selective activator of EIF2AK3/PERK signalling.
abstract: Human cancers often contain genetic alterations that disable G1/S checkpoint control and loss of this checkpoint is thought to critically contribute to cancer generation by permitting inappropriate proliferation and distorting fate-driven cell cycle exit. The identification of cell permeable small molecules that activate the G1/S checkpoint may therefore represent a broadly applicable and clinically effective strategy for the treatment of cancer. Here we describe the identification of several novel small molecules that trigger G1/S checkpoint activation and characterise the mechanism of action for one, CCT020312, in detail. Transcriptional profiling by cDNA microarray combined with reverse genetics revealed phosphorylation of the eukaryotic initiation factor 2-alpha (EIF2A) through the eukaryotic translation initiation factor 2-alpha kinase 3 (EIF2AK3/PERK) as the mechanism of action of this compound. While EIF2AK3/PERK activation classically follows endoplasmic reticulum (ER) stress signalling that sets off a range of different cellular responses, CCT020312 does not trigger these other cellular responses but instead selectively elicits EIF2AK3/PERK signalling. Phosphorylation of EIF2A by EIF2A kinases is a known means to block protein translation and hence restriction point transit in G1, but further supports apoptosis in specific contexts. Significantly, EIF2AK3/PERK signalling has previously been linked to the resistance of cancer cells to multiple anticancer chemotherapeutic agents, including drugs that target the ubiquitin/proteasome pathway and taxanes. Consistent with such findings CCT020312 sensitizes cancer cells with defective taxane-induced EIF2A phosphorylation to paclitaxel treatment. Our work therefore identifies CCT020312 as a novel small molecule chemical tool for the selective activation of EIF2A-mediated translation control with utility for proof-of-concept applications in EIF2A-centered therapeutic approaches, and as a chemical starting point for pathway selective agent development. We demonstrate that consistent with its mode of action CCT020312 is capable of delivering potent, and EIF2AK3 selective, proliferation control and can act as a sensitizer to chemotherapy-associated stresses as elicited by taxanes.
authors.affiliation: Research Department of Cancer Biology, UCL Cancer Institute, London, United Kingdom.
authors.forename: Simon R
authors.initials: SR
authors.lastname: Stockwell
authors.forename: Georgina
authors.initials: G
authors.lastname: Platt
authors.forename: S Elaine
authors.initials: SE
authors.lastname: Barrie
authors.forename: Georgia
authors.initials: G
authors.lastname: Zoumpoulidou
authors.forename: Robert H
authors.initials: RH
authors.lastname: Te Poele
authors.forename: G Wynne
authors.initials: GW
authors.lastname: Aherne
authors.forename: Stuart C
authors.initials: SC
authors.lastname: Wilson
authors.forename: Peter
authors.initials: P
authors.lastname: Sheldrake
authors.forename: Edward
authors.initials: E
authors.lastname: McDonald
authors.forename: Mathilde
authors.initials: M
authors.lastname: Venet
authors.forename: Christelle
authors.initials: C
authors.lastname: Soudy
authors.forename: Frédéric
authors.initials: F
authors.lastname: Elustondo
authors.forename: Laurent
authors.initials: L
authors.lastname: Rigoreau
authors.forename: Julian
authors.initials: J
authors.lastname: Blagg
authors.forename: Paul
authors.initials: P
authors.lastname: Workman
authors.forename: Michelle D
authors.initials: MD
authors.lastname: Garrett
authors.forename: Sibylle
authors.initials: S
authors.lastname: Mittnacht
mesh_terms: D000818:Animals; D016000:Cluster Analysis; D019938:Cyclin D1 / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D004353:Drug Evaluation, Preclinical; D004347:Drug Interactions; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D020536:Enzyme Activators / Q000737:chemistry / Q000494:pharmacology*; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism; D059585:G1 Phase Cell Cycle Checkpoints / Q000187:drug effects*; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D020411:Oligonucleotide Array Sequence Analysis; D017239:Paclitaxel / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D016160:Retinoblastoma Protein / Q000378:metabolism; D059807:S Phase Cell Cycle Checkpoints / Q000187:drug effects*; D015398:Signal Transduction / Q000187:drug effects*; D059467:Transcriptome / Q000187:drug effects / Q000235:genetics; D019892:eIF-2 Kinase / Q000378:metabolism*
chemical_list: D019938:Cyclin D1; D018076:DNA, Complementary; D020536:Enzyme Activators; D015852:Eukaryotic Initiation Factor-2; D017239:Paclitaxel; D016160:Retinoblastoma Protein; D019892:eIF-2 Kinase