Prognostic evaluation of epidermal fatty acid-binding protein and calcyphosine, two proteins implicated in endometrial cancer using a proteomic approach

With the aim to translate the discovery from proteomic research into clinical applications, we identified epidermal fatty acid-binding protein (E-FABP) and calcyphosine (CAPS) by MALDI-Q-TOF MS and validated their overexpressions by immunoblotting. Their expression statuses were examined by immunohistochemistry in 39 normal endometrium, 29 endometrial intraepithelial neoplasia (EIN) and 84 endometrial cancer (EC.) cases. We evaluated the correlations to the clinicopathologic characteristics and determined whether these proteins had prognostic significance. Expressions of E-FABP and CAPS were increased 2.64- and 2.18-fold in EC by immunoblotting. Immunoreactivity of both E-FABP and CAPS were stronger in EC than in EIN or normal tissues (p < 0.001 and < 0.001). Stronger immunoreactivity of E-FABP and CAPS were shown to present with poor differentiation (p = 0.032 and 0.001), but no relevance was observed with staging (p = 1.368 and 4.306). Survival analysis indicated that immunoreactivity of CAPS was correlated to poor survival (p = 0.018), but E-FABP status appeared to be no correlation to the clinical outcome of patients (p = 0.865). Multivariate analysis indicated that CAPS might be an independent prognostic factor for survival in patients with EC (p = 0.008). Results demonstrated the ubiquitous overexpressions of E-FABP and CAPS in EC and the correlations to the clinicopathologic parameters. CAPS might be a potential prognostic factor for survival in patients with EC. The research pattern from proteomics to clinical specimens would have widespread applications. (C) 2008 Wiley-Liss, Inc.