Expression analysis and clinical significance of CXCL16/CXCR6 in patients with bladder cancer

Abstract

The interactions between chemokines and their receptors are closely involved in the progression and metastasis of cancer. We hypothesized that the CXCL16-CXCR6 ligand-receptor system plays an important role in bladder cancer progression. To evaluate this hypothesis, the expression levels of CXCL16 and CXCR6 were evaluated in 160 patients, including 155 patients with bladder cancer and 5 patients with benign bladder disease. The tissues were analyzed by immunohistochemical (IHC) staining and real-time reverse-transcription polymerase chain reaction. We compared the expression of CXCL16/CXCR6 in bladder cancer and benign bladder disease. The expression of CXCR6 was increased in patients with bladder cancer compared with benign bladder disease in RT-PCR. The mRNA expression levels of CXCL16 and CXCR6 were 1.75×10(-2) and 1.99×10(-2) in benign bladder tissue and 1.39×10(-2) and 2.32×10(-2) in bladder cancer tissue, respectively. In IHC staining, the expression of CXCL16/CXCR6 in bladder cancer tissues was higher compared with benign bladder tissues. On multivariate analysis, the IHC staining of CXCL16 was correlated with the 2004 WHO grade and lymphovascular invasion (P=0.021 and P=0.011, respectively). CXCR6 was correlated with the 1973 WHO grade (P=0.001), 2004 WHO grade (P<0.001), pathological T stage (P=0.002) and perineural invasion (P=0.031). However, Cox regression analysis revealed that the expression of CXCL16 and CXCR6 was not correlated with cancer recurrence and cancer-specific survival (P=0.142 and P=0.324, respectively). The expression of CXCL16/CXCR6 was higher in bladder cancer compared to benign disease and correlated with aggressive cancer behavior. Based on our results, the CXCL16/CXCR6 axis appears to be important in the progression of bladder cancer. Thus, CXCL16 and CXCR6 serve as potential therapeutic targets.