In this study, we analyzed Claudin-1 and Claudin-4 expressions in colon carcinomas. We investigated the relationship between the expression of these tight junction proteins and clinicopathologic parameters. Claudin-1 and 4 expressions were determined by immunohistochemical methods, and the rate of cells expressing these tight junction proteins were calculated with stereologic methods. Fifty-nine colon cancer cases were enrolled in the study group. Claudin-1 and 4 expressions were found to be significantly lower in cases with lymph node metastasis. Mean staining rates of Claudin-1 and 4 in lymph node (+) cases were 36.1±20.1 and 58±28.9, while in lymph node (-) cases, these were 63.8±25.9 and 72.3±25.6, respectively (p=0.0005 for Claudin-1, p=0.049 for Claudin-4). The mean staining rate for Claudin-1 in adenomatous polyps was significantly higher than incarcinomas (77.13±23.4 and 50.6±26.93, respectively) (p=0.003), while it was quite similar for Claudin-4 (65.4±26.9 and 65.3±27.9, respectively). In this study, we demonstrated Claudin-1 and 4 expressions in colon cancer cases. Claudin-1 expression seems to be more prominent in adenomatous polyps as compared with cancer cases. Expression of Claudin-1 decreases significantly in the presence of lymph node metastasis and diminishes in mucinous carcinoma cases, indicating a negative correlation between Claudin-1 expression and neoplastic progression.
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