FGFR3 and Ras gene mutations are mutually exclusive genetic events in urothelial cell carcinoma

Abstract

Fibroblast growth factor receptor 3 (FGFR3) mutations are frequent in superficial urothelial cell carcinoma (UCC). Ras gene mutations are also found in UCC. As oncogenic activation of both FGFR3 and Ras is predicted to result in stimulation of the mitogen-activated protein kinase (MAPK) pathway, we hypothesized that these might be mutually exclusive events. HRAS mutation has been widely studied in UCC, but all three Ras gene family members have not been screened for mutation in the same sample series. We screened 98 bladder tumours and 31 bladder cell lines for mutations in FGFR3, HRAS, NRAS and KRAS2. FGFR3 mutations were present in 54 tumours (55%) and three cell lines (10%), and Ras gene mutations in 13 tumours (13%) and four cell lines (13%). These included mutations in all three Ras genes; ten in HRAS, four in KRAS2 and four in NRAS and these were not associated with either tumour grade or stage. In no cases were Ras and FGFR3 mutation found together. This mutual exclusion suggests that FGFR3 and Ras gene mutation may represent alternative means to confer the same phenotype on UCC cells. If these events have biological equivalence, Ras mutant invasive UCC may represent a novel subgroup.

Genetic analysis of multifocal superficial urothelial cancers by array-based comparative genomic hybridisation

“…Three regions of interest containing the previously identified mutations were amplified by PCR (Jebar et al, 2005) using the following primer pairs: for exon 7, 5 0 -AGTGGCGG TGGTGGTGAGGGAG-3 0 and 5 0 -TGTGCGTCACTGTACACCTTGC AG-3 0 ; for exon 10, 5 0 -CCTCAACGCCCATGTCTTT-3 0 and 5 0 -GGG AGCCCAGGCCTTTCTTG-3 0 ; and for exon 15, 5 0 -CCGCAATGT GCTGGTGAC-3 0 and 5 0 -GGCGTCCTACTGGCATGA-3 0 . PCR amplicons were purified using a PCR purification kit (Qiagen, Hilden, Germany) and then directly sequenced with the same primers that were used for the initial PCR and the ABI Prism 310 genetic analysis system (Applied Biosystems, Warrington, UK).…”

“…Mutations of FGFR3 are strongly associated with a low tumour grade and stage, with up to 60 -70% of low-grade pTa tumours showing these mutations (Billerey et al, 2001;van Rhijn et al, 2001;Jebar et al, 2005). Therefore, in addition to chromosomal alterations, FGFR3 mutations are used as a clonal marker.…”

Personalized medicine in advanced urothelial cancer: when to treat, how to treat and who to treat

“…30 Finally, improved characterization of the molecular pathways driving bladder cancer resulted in the identification of disease biomarkers that suggest the following therapeutic angles: mutations of fibroblast growth factor receptor 3 tyrosine kinase receptor are associated with superficial bladder cancer and a promising target for novel therapies. 38 The epidermal growth factor receptor (EGFR) pathway, associated with invasion and poor prognosis, may Advanced urothelial cancer be targeted with EGFR-family tyrosine kinase inhibitors. 39 In our group, we have identified two novel, independent prognostic factors for patient prognosis that themselves suggest new therapeutic angles.…”

Expression profiling of Ral-depleted bladder cancer cells identifies RREB-1 as a novel transcriptional Ral effector

“…We chose to focus on the UMUC-3 human bladder cancer cell line because: (1) it is derived from an invasive tumor (Grossman et al, 1986) and maintains high in vitro migration (Oxford et al, 2005) and invasion (Wu et al, 2004) activities, (2) it has measurably active RalA and RalB (Oxford et al, 2005), presumably, in part, due to harboring an activating K-Ras mutation (Jebar et al, 2005) and (3) we had previously shown in this cell line that siRNAmediated RalB depletion results in decreased cell motility and that depletion of both RalA and RalB impairs cell proliferation (Oxford et al, 2005). We performed gene expression analysis using oligonucleotide arrays on UMUC-3 cells that had been transfected with siRNA specific for RalA, RalB or both RalA and RalB.…”