Summary
Aim: The analysis of the presence of B-Raf gene mutations in relation to ERK1/2 activation in bladder urothelial carcinoma (UC), in order to determine their potential role in tumour aggressiveness and patients' survival.
Methods: Polymerase chain reaction-single strand confirmation polymorphism (PCR-SSCP) and sequencing analysis were used for B-Raf gene mutation detection. pERK1/2 and FGFR3 expression were examined by immunohistochemistry in 152 and 116 primary UCs, respectively.
Results: None of the cases displayed mutations in exon 15 of B-Raf gene. Nuclear or cytoplasmic pERK immunoreactivity was displayed in 99.3% and 96.7% of cases, respectively. pERK nuclear expression increased with histological grade and with T-category. Nuclear and cytoplasmic pERK expression was unrelated to FGFR3 expression. In univariate survival analysis of muscle-invasive carcinomas, advanced T-category and higher pERK nuclear expression (p = 0.018) adversely affected survival. However, multivariate analysis in non-invasive as well as in muscle-invasive carcinomas selected only T-category as a significant prognosticator.
Conclusions: Our findings suggest that elevated pERK expression occurs in UCs in the absence of B-Raf mutations and is not correlated with FGFR3 over-expression. Moreover, it implicates ERK activation in the acquisition of a more aggressive phenotype. However, the assessment of pERK1/2 expression does not seem to add to the prognostic information provided by classical prognosticators.
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