[The clinical significance of expression and amplification of FGF3 in bladder transitional cell carcinoma].

OBJECTIVE: To investigate the amplification and expression of FGF3 in bladder transitional cell carcinoma (BTCC) and its clinical significance. METHODS: Immunohistochemistry (IHC) and Fluorescence In Situ Hybridization (FISH) methods were used to examine the protein expression and amplification of FGF3 in a tissue microarray (TMA) of 100 BTCCs and 30 adjacent normal bladder mucosas, so as to analyze their correlation and association with patient's clinico-pathological features. RESULTS: In this study, none of the normal bladder mucosas were detected FGF3 positivity, while in 89 informative BTCCs, 20 (22%) cases were observed positive expression of FGF3 protein, and it was significantly more frequently to occur in BTCCs of poor-differentiation (Grade 3), later clinical stage (T2-4) and tumor in >or= 3 cm in diameter (P < 0.05). In FISH study, 10 of the 63 (16%) informative BTCCs were observed amplification of FGF3 and it was significantly associated with BTCC's tumor size and clinical stage (P < 0.05). In addition, 10 BTCCs with amplification of FGF3 in this study were all detected positive expression of FGF3 protein, while in the remaining 53 BTCCs without amplification of FGF3, only 3 (6%) cases were observed FGF3 protein positivity. CONCLUSION: The up-regulated expression of FGF3 in BTCC was associated closely with tumor's malignant clinical phenotypes, and it might be involved in the malignant progression of parts of BTCC. The amplification of FGF3 gene might be a predominant mechanism of increased expression of FGF3 protein in BTCC.