Intracellular chloride ion channel protein-1 expression in clear cell renal cell carcinoma

Background/Aim: Chloride intracellular channel 1 (CLIC1) represents a promising target for personalized therapy. Our aim was to assess CLIC1 expression in clear cell renal cell carcinoma (cc RCC) and identify its possible prognostic role. Materials and Methods: Fifty cases of cc RCC were evaluated and selected for immunohistochemistry. CLIC1 expression was correlated with tumor grade, invasion and heterogeneity. Results: A total of 87.5% of the cases were CLIC1 positive, with either a homogeneous (31.42%) or a heterogeneous (68.57%) pattern. Low, mild and strong CLIC1 expressing tumors were defined based on nuclear (N), cytoplasmic (C), membrane (M) or combinations of them (NC, NM, CM, NCM) in terms of CLIC1 distribution. A significant correlation was found between tumor grade and percent of positive tumor cells (p=0.017). For G3 tumors, CLIC1 cytoplasmic expression was strongly correlated with high expression status (p=0.025) and tumor heterogeneity (p=0.004). CLIC1 expression was also correlated with metastasis (p=0.046). Conclusion: We defined four cc RCC groups depending on G, CLIC1 expression and pattern: I) G3/NM/low CLIC1+, ii) G2/CM/mild CLIC1+ iii) G1 or G2/NM or CM/high CLIC1+, and iv) G2/M/high CLIC1+.