Reduced expression of PinX1 correlates to progressive features in patients with prostate cancer

BACKGROUND: Pin2/TRF1 binding protein X1 (PinX1) has been identified as an endogenous telomerase inhibitor and a major haploinsufficient tumor suppressor gene. Increasing evidence suggests that reduced expression of PinX1 plays a key role in tumorigenesis. However, the PinX1 expression status and its correlation with the clinicopathological features in prostate cancer (PCa) have not been investigated. METHODS: PinX1 mRNA and protein expression in PCa and adjacent normal prostate tissues were evaluated by real-time quantitative RT-PCR (qRT-PCR) and western blotting. The clinicopathological significance of PinX1 was investigated by immunohistochemistry (IHC) analysis on a PCa tissue microarray (TMA). The cut-off score for positive expression of PinX1 was determined by the receiver operating characteristic (ROC) analysis. The correlation between PinX1 expression and clinicopathological features of PCa was analyzed by Chi-square test. RESULTS: Reduced expression of PinX1 mRNA and protein was observed in the majority of PCa, compared with their paired adjacent normal prostate tissues. When PinX1 positive expression percentage was determined to be above 60% (area under ROC curve = 0.833, P = 0.000), positive expression of PinX1 was observed in 100% (8/8) of normal prostate tissues and 32.5% (13/40) of PCa tissues by IHC. Reduced expression of PinX1 in patients was correlated with advanced clinical stage (χ(2) = 10.230, p = 0.017), high Gleason score (χ(2) = 4.019, p = 0.045), positive regional lymph node metastasis (χ(2) = 10.852, p = 0.004) and distant metastasis (χ(2) = 7.965, p = 0.005). CONCLUSIONS: Our findings suggest that reduced expression of PinX1 is correlates to progressive features in patients with PCa and may serve as a potential marker for diagnosis.