title: Identification of GRB2 and GAB1 coexpression as an unfavorable prognostic factor for hepatocellular carcinoma by a combination of expression profile and network analysis.
abstract: OBJECTIVE
  To screen novel markers for hepatocellular carcinoma (HCC) by a combination of expression profile, interaction network analysis and clinical validation.
  
  
  METHODS
  HCC significant molecules which are differentially expressed or had genetic variations in HCC tissues were obtained from five existing HCC related databases (OncoDB.HCC, HCC.net, dbHCCvar, EHCO and Liverome). Then, the protein-protein interaction (PPI) network of these molecules was constructed. Three topological features of the network ('Degree', 'Betweenness', and 'Closeness') and the k-core algorithm were used to screen candidate HCC markers which play crucial roles in tumorigenesis of HCC. Furthermore, the clinical significance of two candidate HCC markers growth factor receptor-bound 2 (GRB2) and GRB2-associated-binding protein 1 (GAB1) was validated.
  
  
  RESULTS
  In total, 6179 HCC significant genes and 977 HCC significant proteins were collected from existing HCC related databases. After network analysis, 331 candidate HCC markers were identified. Especially, GAB1 has the highest k-coreness suggesting its central localization in HCC related network, and the interaction between GRB2 and GAB1 has the largest edge-betweenness implying it may be biologically important to the function of HCC related network. As the results of clinical validation, the expression levels of both GRB2 and GAB1 proteins were significantly higher in HCC tissues than those in their adjacent nonneoplastic tissues. More importantly, the combined GRB2 and GAB1 protein expression was significantly associated with aggressive tumor progression and poor prognosis in patients with HCC.
  
  
  CONCLUSIONS
  This study provided an integrative analysis by combining expression profile and interaction network analysis to identify a list of biologically significant HCC related markers and pathways. Further experimental validation indicated that the aberrant expression of GRB2 and GAB1 proteins may be strongly related to tumor progression and prognosis in patients with HCC. The overexpression of GRB2 in combination with upregulation of GAB1 may be an unfavorable prognostic factor for HCC.
authors.affiliation: Research center of traditional Chinese medicine theory, Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China.
authors.forename: Yanqiong
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Pathology and Hepatology, Beijing 302 Hospital, Beijing, China.
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Pathology and Hepatology, Beijing 302 Hospital, Beijing, China.
authors.forename: Mei
authors.initials: M
authors.lastname: Yang
authors.affiliation: Research center of traditional Chinese medicine theory, Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China.
authors.forename: Danhua
authors.initials: D
authors.lastname: Wang
authors.affiliation: Department of Pathology and Hepatology, Beijing 302 Hospital, Beijing, China.
authors.forename: Lingxiang
authors.initials: L
authors.lastname: Yu
authors.affiliation: Department of Pathology and Hepatology, Beijing 302 Hospital, Beijing, China.
authors.forename: Chaonan
authors.initials: C
authors.lastname: Guo
authors.affiliation: Department of Pathology and Hepatology, Beijing 302 Hospital, Beijing, China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Guo
authors.affiliation: Research center of traditional Chinese medicine theory, Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China.
authors.forename: Na
authors.initials: N
authors.lastname: Lin
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D014408:Biomarkers, Tumor / Q000235:genetics* / Q000378:metabolism; D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000235:genetics*; D030541:Databases, Genetic; D051380:GRB2 Adaptor Protein / Q000378:metabolism*; D020869:Gene Expression Profiling / Q000379:methods; D053263:Gene Regulatory Networks / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D053208:Kaplan-Meier Estimate; D008113:Liver Neoplasms / Q000235:genetics*; D011379:Prognosis
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D014408:Biomarkers, Tumor; C098587:GAB1 protein, human; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human