title: RIZ1: a potential tumor suppressor in glioma.
abstract: BACKGROUND
  Retinoblastoma protein-interacting zinc-finger gene 1 (RIZ1) displays strong tumor suppressive activities, and its expression is often silenced in many types of human tumors. However, the relationship between RIZ1 expression and glioma prognosis remains unclear.
  
  
  METHODS
  The dysregulation of RIZ1 was evaluated using real-time polymerase chain reaction, western blot, and immunohistochemical analysis of gliomas from 51 patients. Correlation analysis was performed to examine relationships between RIZ1 immunoreactivity, clinicopathological features, and patient prognosis. Also, human malignant glioma U87 and U251 cell lines were stably transduced with ectogenic RIZ1 using a lentiviral vector to investigate the effects of induced expression of RIZ1 on cell proliferation, cell cycle, and apoptosis.
  
  
  RESULTS
  Real-time polymerase chain reaction and western blot analysis showed that RIZ1 was downregulated in high-grade gliomas compared with low-grade gliomas and normal brain tissue. Immunohistochemistry showed less RIZ1 labeling in high-grade gliomas than in low-grade gliomas. There was a negative correlation between RIZ1 and Ki-67 immunoreactivity. Clinicopathological evaluation revealed that RIZ1 expression was negatively correlated with tumor grade and patient age. Kaplan-Meier survival analysis showed a positive correlation between RIZ1 immunoreactivity level and progression-free and overall survival times. Multivariate analysis showed that high RIZ1 expression was an independent prognostic factor for patients with gliomas. Induced expression of RIZ1 in U87 and U251 cells reduced cell proliferation and increased apoptosis, and cell cycle analysis revealed that a majority of cells were arrested at G2-M. Moreover, transfection with a RIZ1 expression vector increased p53 and caspase-3 expression and decreased p-IKBα and p-AKT protein levels, suggesting that RIZ1 may stimulate p53-mediated apoptosis and inhibit p-IKBα and p-AKT signaling pathways.
  
  
  CONCLUSIONS
  Our results suggest that high RIZ1 labeling is indicative of lower grades of gliomas and is associated with better progression-free and overall survival rates. Therefore, RIZ1 may be a promising therapeutic target for patients with gliomas.
authors.affiliation: Department of Neurosurgery, Changzheng Hospital, Second Military Medical University, Shanghai, 200003, China. christopher0708@163.com.
authors.forename: Chenran
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Otolaryngology, Changzheng Hospital, Second Military Medical University, Shanghai, 200003, China. fortheonlyjulia@hotmail.com.
authors.forename: Qiubei
authors.initials: Q
authors.lastname: Zhu
authors.affiliation: Department of Neurosurgery, Changzheng Hospital, Second Military Medical University, Shanghai, 200003, China. panda1979hh@sina.com.
authors.forename: Hua
authors.initials: H
authors.lastname: He
authors.affiliation: Department of Neurosurgery, Changzheng Hospital, Second Military Medical University, Shanghai, 200003, China. jl13jan@gmail.com.
authors.forename: Lei
authors.initials: L
authors.lastname: Jiang
authors.affiliation: Department of Neurology, Huadong Hospital, Fudan University, Shanghai, 200040, China. qiangqiangshsmu@126.com.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Qiang
authors.affiliation: Department of Cardiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China. iam565@126.com.
authors.forename: Liuhua
authors.initials: L
authors.lastname: Hu
authors.affiliation: Department of Neurosurgery, Changzheng Hospital, Second Military Medical University, Shanghai, 200003, China. huguohan6504@sina.com.
authors.forename: Guohan
authors.initials: G
authors.lastname: Hu
authors.affiliation: Department of Neurosurgery, Changzheng Hospital, Second Military Medical University, Shanghai, 200003, China. yiyijijiji@gmail.com.
authors.forename: Ying
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Department of Neurosurgery, Changzheng Hospital, Second Military Medical University, Shanghai, 200003, China. dxuehua.cz@163.com.
authors.forename: Xuehua
authors.initials: X
authors.lastname: Ding
authors.affiliation: Department of Neurosurgery, Changzheng Hospital, Second Military Medical University, Shanghai, 200003, China. luyc305@163.com.
authors.forename: Yicheng
authors.initials: Y
authors.lastname: Lu
mesh_terms: D000328:Adult; D000368:Aged; D017209:Apoptosis / Q000502:physiology; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000378:metabolism* / Q000473:pathology; D002453:Cell Cycle / Q000502:physiology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000502:physiology; D004268:DNA-Binding Proteins / Q000378:metabolism* / Q000502:physiology; D005260:Female; D005910:Glioma / Q000378:metabolism* / Q000473:pathology; D011495:Histone-Lysine N-Methyltransferase / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009687:Nuclear Proteins / Q000378:metabolism* / Q000502:physiology; D060888:Real-Time Polymerase Chain Reaction; D016019:Survival Analysis; D014157:Transcription Factors / Q000378:metabolism* / Q000502:physiology
chemical_list: D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D014157:Transcription Factors; D011495:Histone-Lysine N-Methyltransferase; C093563:PRDM2 protein, human