title: CHK1 overexpression in T-cell acute lymphoblastic leukemia is essential for proliferation and survival by preventing excessive replication stress.
abstract: Checkpoint kinase 1 (CHK1) is a key component of the ATR (ataxia telangiectasia-mutated and Rad3-related)-dependent DNA damage response pathway that protect cells from replication stress, a cell intrinsic phenomenon enhanced by oncogenic transformation. Here, we show that CHK1 is overexpressed and hyperactivated in T-cell acute lymphoblastic leukemia (T-ALL). CHEK1 mRNA is highly abundant in patients of the proliferative T-ALL subgroup and leukemia cells exhibit constitutively elevated levels of the replication stress marker phospho-RPA32 and the DNA damage marker γH2AX. Importantly, pharmacologic inhibition of CHK1 using PF-004777736 or CHK1 short hairpin RNA-mediated silencing impairs T-ALL cell proliferation and viability. CHK1 inactivation results in the accumulation of cells with incompletely replicated DNA, ensuing DNA damage, ATM/CHK2 activation and subsequent ATM- and caspase-3-dependent apoptosis. In contrast to normal thymocytes, primary T-ALL cells are sensitive to therapeutic doses of PF-004777736, even in the presence of stromal or interleukin-7 survival signals. Moreover, CHK1 inhibition significantly delays in vivo growth of xenotransplanted T-ALL tumors. We conclude that CHK1 is critical for T-ALL proliferation and viability by downmodulating replication stress and preventing ATM/caspase-3-dependent cell death. Pharmacologic inhibition of CHK1 may be a promising therapeutic alternative for T-ALL treatment.
authors.affiliation: Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.
authors.forename: L M
authors.initials: LM
authors.lastname: Sarmento
authors.affiliation: Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.
authors.forename: V
authors.initials: V
authors.lastname: Póvoa
authors.affiliation: Infections and Immunity Laboratory, Instituto Gulbenkian de Ciência, Oeiras, Portugal.
authors.forename: R
authors.initials: R
authors.lastname: Nascimento
authors.affiliation: 1] iBET, Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal [2] Instituto de Tecnologia Química e Biológica, Oeiras, Portugal.
authors.forename: G
authors.initials: G
authors.lastname: Real
authors.affiliation: Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.
authors.forename: I
authors.initials: I
authors.lastname: Antunes
authors.affiliation: Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.
authors.forename: L R
authors.initials: LR
authors.lastname: Martins
authors.affiliation: Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.
authors.forename: C
authors.initials: C
authors.lastname: Moita
authors.affiliation: 1] iBET, Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal [2] Instituto de Tecnologia Química e Biológica, Oeiras, Portugal.
authors.forename: P M
authors.initials: PM
authors.lastname: Alves
authors.affiliation: Cardiologia Pediátrica Medico-Cirúrgica, Hospital Sta. Cruz, Carnaxide, Lisbon, Portugal.
authors.forename: M
authors.initials: M
authors.lastname: Abecasis
authors.affiliation: Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.
authors.forename: L F
authors.initials: LF
authors.lastname: Moita
authors.affiliation: Infections and Immunity Laboratory, Instituto Gulbenkian de Ciência, Oeiras, Portugal.
authors.forename: R M E
authors.initials: RM
authors.lastname: Parkhouse
authors.affiliation: Department of Pediatric Oncology/Hematology, Erasmus MC/Sophia Children's Hospital, Rotterdam, The Netherlands.
authors.forename: J P P
authors.initials: JP
authors.lastname: Meijerink
authors.affiliation: Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.
authors.forename: J T
authors.initials: JT
authors.lastname: Barata
mesh_terms: D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism; D001570:Benzodiazepinones / Q000008:administration & dosage / Q000494:pharmacology; D053148:Caspase 3 / Q000378:metabolism; D002453:Cell Cycle; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival; D000071877:Checkpoint Kinase 1; D004249:DNA Damage; D004261:DNA Replication; D055785:Gene Knockdown Techniques; D006801:Humans; D051379:Mice; D009368:Neoplasm Transplantation; D054218:Precursor T-Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism*; D011720:Pyrazoles / Q000008:administration & dosage / Q000494:pharmacology; D060168:Thymocytes / Q000378:metabolism
chemical_list: D001570:Benzodiazepinones; C532366:PF 00477736; D011720:Pyrazoles; D011494:Protein Kinases; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; C000605869:Chek1 protein, mouse; D053148:Caspase 3