Molecular and Immunohistochemical assessment of Fibroblast Growth Factor Receptor 3 (FGFR3) gene as a survival time predictor in bladder cancer patients

Abstract

BACKGROUND: Mutation signatures contributing to the tumorigenesis of bladder cancer (BC) are complex and heterogeneous, resulting in unpredictable progression, recurrence, and time survival. Clinically, useful prognostic and predictive biomarkers for both disease recurrence and surveillance are therefore needed. Activating fibroblast growth factor receptor 3 (FGFR3) mutations are regarded as early drivers in the molecular pathogenesis of BC. AIM: The aim of the present study is to evaluate the frequency and distribution pattern of FGFR3 mutation in urine sediments of BC patients in relation to its immunohistochemical (IHC) and molecular expression and to determine the prognostic and predictive value of FGFR3 relative to BC. PATIENTS AND METHODS: One hundred and sixty patients with diagnosed BC and 80 healthy controls were recruited. Urine samples were  collected from all participants. DNA was extracted and FGFR3 mutations were examined in exons 7, 10, and 15 by polymerase chain reaction. IHC for FGFR3 expression and fluorescence in situ hybridization technique for assessment of gene amplification was also applied in tissue sections. RESULTS: Ninety-eight (61.3%) patients were mutant in exon 7, 82 (51.3%) were mutant in exon 10, while only 14 (8.8%) were mutant in exon 15. Univariate logistic regression analysis revealed that mutations in the three exons of FGFR3 were statistically associated with BC and could be used as predictor and/or prognostic parameters for BC. Receiver operating characteristic analysis showed that the mutation of exons 7 and 10 could be used as diagnostic biomarkers for BC. Our findings confirm that FGFR3 mutations are associated with tumors of low grade and stage. The prevalence of mutations was significantly associated with recurrence and survival time of patients for all exons. Kaplan–Meier analysis revealed a significant association between mutant patients in exon 10 and survival time. Our findings suggest that estimation of FGFR3 expression and gene amplification could serve as a prognostic indicator in the follow-up of BC patients. It could also be utilized for molecular targeted therapy in BC. CONCLUSION: Our data confirmed the feasibility of FGFR3 mutation detection in urine sediment. FGFR3 genetic mutations are independent prognostic factors for tumor recurrence and the genetic alternation of FGFR3 could be used for prediction of survival time of BC patients.