title: Differential expression of the RNA-binding motif protein 3 in human astrocytoma.
abstract: BACKGROUND
  The RNA-binding motif protein 3 (RBM3), which is transcriptionally induced by low temperature and hypoxia, has recently been found to be upregulated in human tumors. However, its expression status in human astrocytoma is not well defned. This article focuses on the differential expression of RBM3 in human astrocytomas of different grades and normal brain tissues.
  
  
  METHODS
  RBM3 was detected in astrocytomas and normal brain tissues by quantitative real-time PCR, immunohistochemistry, and Western blotting. Analysis of variance was performed on the data from quantitative real-time PCR. The Fisher's exact test was used to analyze the immunohistochemistry results. A P-value of less than 0.05 indicates a statistically significant difference.
  
  
  RESULTS
  On one hand, the mRNA expression levels of three X-chromosome-related RBM genes (RBMX, RBM3, and RBM10) were detected by quantitative real-time PCR. The results showed that there were no significant differences in RBMX and RBM10 mRNA expression levels in human astrocytomas of different grades and normal brain tissues. However, RBM3 mRNA expression levels were elevated in high-grade (World Health Organization (WHO) Grade III-IV) astrocytomas versus low-grade (WHO Grade I-II) astrocytomas (5.06 ± 0.66 vs. 1.60 ± 0.58; P < 0.05) or normal controls (5.06 ± 0.66 vs. 1.03 ± 0.22; P < 0.05) as determined by quantitative real-time PCR analysis. On the other hand, immunohistochemistry showed an increased RBM3 labeling index in astrocytomas of different grades and normal brain tissues (positive staining rate: astrocytoma Grade IV, 92.9%; astrocytoma Grade III, 81.8%; astrocytoma Grade I-II, 50%; normal brain tissues, 37.5%; high-grade astrocytoma versus normal brain tissues, P < 0.05; high-grade astrocytoma versus low-grade astrocytoma, P < 0.05). The higher protein levels of RBM3 were also validated in high-grade astrocytomas and low-grade astrocytomas compared with normal brain tissues by Western blotting.
  
  
  CONCLUSIONS
  These data suggest that the overexpression of RBM3 may serve as an important molecular mechanism underlying astrocytic carcinogenesis. Moreover, RBM3 may have proliferative and/or proto-oncogenic functions in human astrocytomas.
authors.affiliation: Department of Neurosurgery, First Affiliated Hospital of People's Liberation Army General Hospital, Beijing 100048, China.
authors.forename: Hai-Tao
authors.initials: HT
authors.lastname: Zhang
authors.forename: Zhi-Wen
authors.initials: ZW
authors.lastname: Zhang
authors.forename: Jing-Hui
authors.initials: JH
authors.lastname: Xue
authors.forename: Hai-Bo
authors.initials: HB
authors.lastname: Kong
authors.forename: Ai-Jun
authors.initials: AJ
authors.lastname: Liu
authors.forename: Shou-Chun
authors.initials: SC
authors.lastname: Li
authors.forename: Yu-Xiao
authors.initials: YX
authors.lastname: Liu
authors.forename: Dong-Gang
authors.initials: DG
authors.lastname: Xu
mesh_terms: D001254:Astrocytoma / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D006801:Humans; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: C099506:RBM3 protein, human; D016601:RNA-Binding Proteins