Expression and Prognostic Roles of TRPV5 and TRPV6 in Non-Small Cell Lung Cancer after Curative Resection

Purpose: We investigated the expression of epithelial Ca2+ channel transient receptor potential vanilloid(TRPV) 5 and 6 in non-small-cell lung cancer (NSCLC) and assessed their prognostic role in patients aftersurgical resection. Materials and
Methods: From January 2008 to January 2009, 145 patients who had undergonesurgical resection of NSCLCs were enrolled in the study. Patient clinical characteristics were retrospectivelyreviewed. Fresh tumor samples as well as peritumor tissues were analyzed for TRPV5/6 expression usingimmune-histochemistry (IHC) and quantitative reverse transcriptase-polymerase chain reaction (RT-PCR).Patients were grouped based on their TRPV5 and TRPV6 levels in the tumor tissues, followed up after surgery,and statistically analyzed to examine the prognostic roles of TRPV5 and TRPV6 on patients’ survival aftersurgical resection of NSCLCs.
Results: Using IHC, among the 145 patients who had undergone surgical resectionof NSCLCs, strong protein expression (grade≥2) of TRPV5 and TRPV6 was observed in a lower percentageof primary tumor tissues than in non-tumor tissues of same patients. Similar findigns were obtained with theRT-PCR test for mRNA levels. Decreased overall mRNA levels of TRPV5 and TRPV6 were associated with aworse overall survival rate (p=0.004 and p=0.003 respectively) and shorter recurrence-free survival (p﹤0.001 andp﹤0.001 respectively). The combining effect of TRPV5 and TRPV6 on survival was further investigated usingmultivariate analysis. The results showed that a combination of low expression of TRPV5 and TRPV6 couldbe an independent predictor of poor recurrence-free survival (p=0.002).
Conclusions: Decreased expression ofTRPV5/6 in tumor tissues was observed in NSCLC patients and was associated with shorter median survival timeafter surgical resection. Combined expression of TRPV5 and TRPV6 in tumor tissues demonstrated promisingprognostic value in NSCLC patients.