title: CHK1 plays a critical role in the anti-leukemic activity of the wee1 inhibitor MK-1775 in acute myeloid leukemia cells.
abstract: BACKGROUND
  Acute myeloid leukemia (AML) remains a difficult disease to treat and requires new therapies to improve treatment outcome. Wee1 inhibitors have been used to prevent activation of the G2 cell cycle checkpoint, thus enhancing the antitumor activity of DNA damaging agents. In this study, we investigated MK-1775 in AML cell lines and diagnostic blast samples to identify sensitive subtypes as well as possible mechanisms of resistance.
  
  
  METHODS
  In vitro MK-1775 cytotoxicities of AML cell lines and diagnostic blasts were measured using MTT assays. The effects of MK-1775 on cell cycle progression and related proteins were determined by propidium iodide (PI) staining and flow cytometry analysis and Western blotting. Drug-induced apoptosis was determined using annexin V/PI staining and flow cytometry analysis.
  
  
  RESULTS
  We found that newly diagnosed and relapsed patient samples were equally sensitive to MK-1775. In addition, patient samples harboring t(15;17) translocation were significantly more sensitive to MK-1775 than non-t(15;17) samples. MK-1775 induced apoptosis in both AML cell lines and diagnostic blast samples, accompanied by decreased phosphorylation of CDK1 and CDK2 on Tyr-15 and increased DNA double-strand breaks (DSBs). Time-course experiments, using AML cell lines, revealed a time-dependent increase in DNA DSBs, activation of CHK1 and subsequent apoptosis following MK-1775 treatment, which could be attenuated by a CDK1/2 inhibitor, Roscovitine. Simultaneous inhibition of CHK1 and Wee1 resulted in synergistic anti-leukemic activity in both AML cell lines and primary patient samples ex vivo.
  
  
  CONCLUSIONS
  Our study provides compelling evidence that CHK1 plays a critical role in the anti-leukemic activity of MK-1775 and highlights a possible mechanism of resistance to MK-1775. In addition, our study strongly supports the use of MK-1775 to treat both newly diagnosed and relapsed AML, especially cases with t(15;17) translocation, and supports the development of combination therapies with CHK1 inhibitors.
authors.forename: Wenxiu
authors.initials: W
authors.lastname: Qi
authors.forename: Chengzhi
authors.initials: C
authors.lastname: Xie
authors.forename: Chunhuai
authors.initials: C
authors.lastname: Li
authors.forename: J Timothy
authors.initials: JT
authors.lastname: Caldwell
authors.forename: Holly
authors.initials: H
authors.lastname: Edwards
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Taub
authors.affiliation: National Engineering Laboratory for AIDS Vaccine, Key Laboratory for Molecular Enzymology & Engineering, the Ministry of Education, and School of Life Sciences, Jilin University, Changchun, China. wangyue7373@126.com.
authors.forename: Yue
authors.initials: Y
authors.lastname: Wang
authors.forename: Hai
authors.initials: H
authors.lastname: Lin
authors.forename: Yubin
authors.initials: Y
authors.lastname: Ge
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors; D045744:Cell Line, Tumor; D000071877:Checkpoint Kinase 1; D005434:Flow Cytometry; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000378:metabolism*; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors; D011494:Protein Kinases / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011720:Pyrazoles / Q000494:pharmacology*; D011743:Pyrimidines / Q000494:pharmacology*; D011744:Pyrimidinones; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D018797:Cell Cycle Proteins; D009687:Nuclear Proteins; D011720:Pyrazoles; D011743:Pyrimidines; D011744:Pyrimidinones; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; C499349:WEE1 protein, human; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; C549567:adavosertib
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