The expression of C-FABP and PPARγ and their prognostic significance in prostate cancer

The purpose of this study was to test the hypothesis that cooperative interaction between cutaneous fatty acid-binding protein (C-FABP) and peroxisome proliferator-activated receptors (PPAR) promotes the malignant progression of human prostate cancer. The expression of C-FABP, PPAR/ and PPAR was measured by western blot analysis in prostate cell lines and by immunohistochemical staining in tissue sections of benign prostatic hyperplasia (BPH) and prostatic carcinomas. The correlation between the expression of PPARs and C-FABP was assessed. The significance of increased expression of these proteins was analysed with respect to prognosis and compared with those of alternative biomarkers. The expression levels of C-FABP and PPAR in prostate cancer cell lines and the cytoplasm and nuclei of carcinoma tissues were significantly (Student's t-test, p<0.05) higher compared to those in benign cell lines and BPH tissues. The raised expression level of C-FABP and PPAR was significantly correlated with the increased combined Gleason scores (GS) of the carcinomas. Enhanced expression of cytoplasmic C-FABP significantly correlated with increased nuclear PPAR (Student's t-test, p<0.005). While expression of PPAR/ in carcinomas did not correlate with patient outcome, the increased levels of both C-FABP and PPAR were associated with shorter patient survival. Multivariate analysis indicated that C-FABP was independently associated with patient survival, whereas PPAR was confounded by C-FABP in predicting patient survival. Thus, the increased C-FABP may interact with PPAR in a coordinated mechanism to facilitate malignant progression in prostatic cancer. Both C-FABP and PPAR are suitable as prognostic factors to predict the clinical outcome of prostatic cancer patients.