title: Targeting of Carbon Ion-Induced G2 Checkpoint Activation in Lung Cancer Cells Using Wee-1 Inhibitor MK-1775.
abstract: The potent inhibitor of the cell cycle checkpoint regulatory factor Wee-1, MK-1775, has been reported to enhance non-small cell lung cancer (NSCLC) cell sensitivity to photon radiation by abrogating radiation-induced G2 arrest. However, little is known about the effects of this sensitizer after exposure to carbon (C)-ion radiation. The purpose of this study was therefore to investigate the effects of C ions in combination with MK-1775 on the killing of NSCLC cells. Human NSCLC H1299 cells were exposed to X rays or C ions (290 MeV/n, 50 keV/μm at the center of a 6 cm spread-out Bragg peak) in the presence of MK-1775. The cell cycle was analyzed using flow cytometry and Western blotting. Radiosensitivity was determined using clonogenic survival assays. The mechanisms underlying MK-1775 radiosensitization were studied by observing H2AX phosphorylation and mitotic catastrophe. G2 checkpoint arrest was enhanced 2.3-fold by C-ion exposure compared with X-ray exposure. Radiation-induced G2 checkpoint arrest was abrogated by MK-1775. Exposure to radiation resulted in a significant reduction in the mitotic ratio and increased phosphorylation of cyclin-dependent kinase 1 (Cdk1), the primary downstream mediator of Wee-1-induced G2 arrest. The Wee-1 inhibitor, MK-1775 restored the mitotic ratio and suppressed Cdk1 phosphorylation. In addition, MK-1775 increased H1299 cell sensitivity to C ions and X rays independent of TP53 status. MK-1775 also significantly increased H2AX phosphorylation and mitotic catastrophe in irradiated cells. These results suggest that the G2 checkpoint inhibitor MK-1775 can enhance the sensitivity of human NSCLC cells to C ions as well as X rays.
authors.affiliation: a  Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Japan; and.
authors.forename: Hongyu
authors.initials: H
authors.lastname: Ma
authors.affiliation: b  Gunma University Heavy Ion Medical Center, Maebashi, Japan.
authors.forename: Akihisa
authors.initials: A
authors.lastname: Takahashi
authors.affiliation: b  Gunma University Heavy Ion Medical Center, Maebashi, Japan.
authors.forename: Yukihiko
authors.initials: Y
authors.lastname: Sejimo
authors.affiliation: a  Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Japan; and.
authors.forename: Akiko
authors.initials: A
authors.lastname: Adachi
authors.affiliation: a  Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Japan; and.
authors.forename: Nobuteru
authors.initials: N
authors.lastname: Kubo
authors.affiliation: b  Gunma University Heavy Ion Medical Center, Maebashi, Japan.
authors.forename: Mayu
authors.initials: M
authors.lastname: Isono
authors.affiliation: b  Gunma University Heavy Ion Medical Center, Maebashi, Japan.
authors.forename: Yukari
authors.initials: Y
authors.lastname: Yoshida
authors.affiliation: b  Gunma University Heavy Ion Medical Center, Maebashi, Japan.
authors.forename: Tatsuaki
authors.initials: T
authors.lastname: Kanai
authors.affiliation: b  Gunma University Heavy Ion Medical Center, Maebashi, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Ohno
authors.affiliation: a  Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Japan; and.|b  Gunma University Heavy Ion Medical Center, Maebashi, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakano
mesh_terms: D002244:Carbon; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors*; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D059565:G2 Phase Cell Cycle Checkpoints / Q000528:radiation effects*; D063193:Heavy Ion Radiotherapy / Q000379:methods; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D011720:Pyrazoles / Q000008:administration & dosage*; D011743:Pyrimidines / Q000008:administration & dosage*; D011744:Pyrimidinones; D011838:Radiation-Sensitizing Agents / Q000008:administration & dosage*; D016896:Treatment Outcome
chemical_list: D018797:Cell Cycle Proteins; D009687:Nuclear Proteins; D011720:Pyrazoles; D011743:Pyrimidines; D011744:Pyrimidinones; D011838:Radiation-Sensitizing Agents; D002244:Carbon; D011505:Protein-Tyrosine Kinases; C499349:WEE1 protein, human; C549567:adavosertib