Chloride Intracellular Channel Protein 1 (CLIC1) Is Over-expressed in Muscle Invasive Urinary Bladder Cancer

Background/Aim: Invasive bladder cancer mortality remains high despite progresses made in early diagnosis and surgical procedures. Thus, there is a need to define new markers for bladder cancer. CLIC1 has not been previously studied in bladder cancer and thus, we aimed to assess its immunohistochemical expression in relation to different stages of bladder cancer development. Materials and Methods: Immunohistochemistry for CLIC1 was applied in 50 cases of muscle invasive bladder cancer. Results: CLIC1 was not expressed in the normal urothelium, but a strong reaction was observed in dysplastic urothelium, carcinoma in situ and in 94% of the cases with invasive urothelial carcinoma; however, it was not expressed in squamous cell carcinoma cases. No correlation was found between the immunohistochemical expression of CLIC1 and the stage and grade of the tumour. Conclusion: CLIC1 was overexpressed in urinary bladder dysplastic epithelium, carcinoma in situ and invasive carcinoma. CLIC1 constitutes a new potential marker of invasive bladder cancer.