title: Assessment of vascular endothelial growth factor in formalin fixed, paraffin embedded colon cancer specimens by means of a well-based reverse phase protein array.
abstract: BACKGROUND
  Vascular endothelial growth factor (VEGF) is a critical pro-angiogenic factor, found in a number of cancers, and a target of therapy. It is typically assessed by immunohistochemistry (IHC) in clinical research. However, IHC is not a quantitative assay and is rarely reproducible. We compared VEGF levels in colon cancer by IHC and a quantitative immunoassay on proteins isolated from formalin fixed, paraffin embedded tissues.
  
  
  RESULTS
  VEGF expression was studied by means of a well-based reverse phase protein array (RPPA) and immunohistochemistry in 69 colon cancer cases, and compared with various clinicopathologic factors. Protein lysates derived from formalin fixed, paraffin embedded tissue contained measurable immunoreactive VEGF molecules. The VEGF expression level of well differentiated colon cancer was significantly higher than those with moderately and poorly differentiated carcinomas by immunohistochemistry (P = 0.04) and well-based RPPA (P = 0.04). VEGF quantification by well-based RPPA also demonstrated an association with nodal metastasis status (P = 0.05). In addition, the normalized VEGF value by well-based RPPA correlated (r = 0.283, P = 0.018). Furthermore, subgroup analysis by histologic type revealed that adenocarcinoma cases showed significant correlation (r = 0.315, P = 0.031) between well-based RPPA and IHC.
  
  
  CONCLUSIONS
  The well-based RPPA method is a high throughput and sensitive approach, is an excellent tool for quantification of marker proteins. Notably, this method may be helpful for more objective evaluation of protein expression in cancer patients.
authors.affiliation: Tissue Array Research Program & Applied Molecular Pathology Lab., Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Joon-Yong
authors.initials: JY
authors.lastname: Chung
authors.affiliation: Institute of Pathology, RWTH Aachen University, Aachen 52074, Germany.
authors.forename: Till
authors.initials: T
authors.lastname: Braunschweig
authors.affiliation: Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, South Korea.
authors.forename: Seung-Mo
authors.initials: SM
authors.lastname: Hong
authors.affiliation: Tissue Array Research Program & Applied Molecular Pathology Lab., Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: David S
authors.initials: DS
authors.lastname: Kwon
authors.affiliation: Department of Statistics, Korea University, Seoul 136-701, South Korea.
authors.forename: Soo-Heang
authors.initials: SH
authors.lastname: Eo
authors.affiliation: Department of Statistics, Korea University, Seoul 136-701, South Korea.
authors.forename: HyungJun
authors.initials: H
authors.lastname: Cho
authors.affiliation: Tissue Array Research Program & Applied Molecular Pathology Lab., Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Hewitt
keywords: Colon cancer; Formalin-fixed paraffin-embedded; Immunohistochemistry; Reverse-phase protein array; Vascular endothelial growth factor