title: RBM5 inhibits tumorigenesis of gliomas through inhibition of Wnt/β-catenin signaling and induction of apoptosis.
abstract: BACKGROUND
  Gliomas are one of the most common malignant brain tumors and bring a big threat to human life as traditional therapy is unsatisfactory. RBM5 was a RNA-binding motif protein and was reported as a tumor suppressor. But the role of RBM5 in gliomas was unknown.
  
  
  METHODS
  The mRNA level of RBM5 was determined in gliomas tissues and cell lines by real-time quantitative PCR (qRT-PCR) assay while the association of RBM5 expression with prognosis was analyzed by Kaplan-Meier method and compared by log-rank test. Lentivirus was used to overexpress RBM5 in gliomas cells. MTT and BrdU incorporation assay were used to determine cell proliferation and DNA synthesis when the ability of cell migration and invasion was analyzed by transwell assay with/without Matrigel. Cell apoptosis rate was determined with fluorescence-activated cell sorting (FACS) method. Then, expression of apoptosis molecules and critical members in Wnt/β-catenin pathway were detected by western blot analysis.
  
  
  RESULTS
  RBM5 was shown to be downregulated in gliomas tissues and gliomas cell lines. And decreased RBM5 expression was clinically correlated with tumor stage, patient age, and poor prognosis of gliomas patients. The proliferation and DNA synthesis was dramatically inhibited when RBM5 was overexpressed in SHG44 or U251 cells. Also, the ability of cell migration and invasion was disrupted. Then, the level of β-catenin and Cyclin D1 significantly decreased when DKK1 and P-GSK-3β increased reversely in SHG44 cells, which suggested that RBM5 inhibited canonical Wnt/β-catenin signaling. Meanwhile, we demonstrated that caspase3-mediated apoptotic pathway was activated by RBM5 as Bax, TNF-α, and cleaved caspase3 were greatly upregulated while antiapoptotic molecule Bcl-2 was downregulated. Additionally, that apoptotic rate increased significantly from less than 1 to 32% in RBM5-overexpressed SHG44 cells further supported the pro-apoptosis role of RBM5 in gliomas cells.
  
  
  CONCLUSIONS
  RBM5 plays a suppressor role in human gliomas by inhibiting Wnt/β-catenin signaling and inducing cell apoptosis. This study improves our knowledge about the carcinogenesis and progression of human gliomas, which would greatly contribute to the therapy for gliomas patients.
authors.affiliation: Department of Neurosurgery, Ji'nan Central Hospital Affiliated to Shandong University, Liberate Road No. 105, Ji'nan, 250013, China.
authors.forename: Yuanpei
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Department of Pediatrics, Shandong Jiaotong Hospital, Central Wuying Hill Road No. 12, Ji'nan, 250031, China.
authors.forename: Hongling
authors.initials: H
authors.lastname: Sheng
authors.affiliation: Department of Neurosurgery, Ji'nan Central Hospital Affiliated to Shandong University, Liberate Road No. 105, Ji'nan, 250013, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Meng
authors.affiliation: Department of Neurosurgery, Ji'nan Central Hospital Affiliated to Shandong University, Liberate Road No. 105, Ji'nan, 250013, China.
authors.forename: Hongsheng
authors.initials: H
authors.lastname: Yue
authors.affiliation: Department of Neurosurgery, Ji'nan Central Hospital Affiliated to Shandong University, Liberate Road No. 105, Ji'nan, 250013, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Li
authors.affiliation: Department of Neurosurgery, Ji'nan Central Hospital Affiliated to Shandong University, Liberate Road No. 105, Ji'nan, 250013, China.
authors.forename: Aijun
authors.initials: A
authors.lastname: Zhang
authors.forename: Yanan
authors.initials: Y
authors.lastname: Dong
authors.affiliation: Department of Neurosurgery, Qilu Hospital affiliated to Shandong University, Cultural West Road No. 107, Ji'nan, 250012, China. liuyuguang_0001@163.com.
authors.forename: Yuguang
authors.initials: Y
authors.lastname: Liu
mesh_terms: D017209:Apoptosis; D014408:Biomarkers, Tumor; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002465:Cell Movement; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005500:Follow-Up Studies; D015972:Gene Expression Regulation, Neoplastic; D005910:Glioma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D011379:Prognosis; D012333:RNA, Messenger / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D015996:Survival Rate; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D051153:Wnt Proteins / Q000235:genetics / Q000378:metabolism*; D060449:Wnt Signaling Pathway; D051176:beta Catenin / Q000378:metabolism*
chemical_list: D014408:Biomarkers, Tumor; C495270:CTNNB1 protein, human; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C473448:RBM5 protein, human; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D025521:Tumor Suppressor Proteins; D051153:Wnt Proteins; D051176:beta Catenin
keywords: Apoptosis; Caspase3; Gliomas; RBM5; Wnt/β-catenin signaling