Over-expression of TRPM8 is associated with poor prognosis in urothelial carcinoma of bladder.

Transient receptor protein (TRP) channels are frequently associated with tumors and are correlated to patient's outcome. We firstly investigated TRP channel melastatin 8 (TRPM8) expression in urothelial carcinoma of bladder (UCB) and its correlation with UCB clinicopathological features and additionally evaluated the association between TRPM8 expression and patients' survival rate to elucidate its role in bladder oncogenesis. Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) was conducted to examine TRPM8 messenger RNA (mRNA) expression in 36 pairs of freshly frozen UCB tissues and matched noncancerous tissues. Immunohistochemistry (IHC) was performed in 156 archived paraffin-embedded UCB samples to explore the correlation between TRPM8 protein and clinicopathological features. The association between TRPM8 expression and patient's survival rate was evaluated using the Kaplan-Meier method and multivariate Cox regression analysis, respectively. The expression levels of TRPM8 mRNA in UCB tissues were significantly higher than those in matched noncancerous tissues (P=0.016). Expression of TRPM8 protein in UCB was significantly and positively associated with histological grade (P=0.039) and tumor stage (P=0.037). Significant correlation between high TRPM8 expression and poor cumulative survival of UCB patients was shown using the Kaplan-Meier survival curve (P=0.039). TRPM8 was represented as an independent prognostic biomarker for UCB patients by multivariate Cox regression analysis (P=0.047). The present study provide the convincing evidence for the first time that over-expression of TRPM8 may play a role in the pathogenesis and progression of UCB, and TRPM8 may serve as an independent prognostic biomarker for UCB patients.