ИСТИНА

Objective: Claudins are members of membrane tight junction proteins. They play critical role in cellular proliferation and neoplastic transformation via their functioning as transmitters of the extracellular stimuli to intracellular signaling pathways. Materials and Methods: Samples of 32 colon adenocarcinomas and 86 premalignant lesions (according to WHO classification, 2010) were included in this study. The aim was the immunohistochemical evaluation of claudin-1, claudin-3 and claudin-4 localization. Results: Typical membrane localization of claudin-1, claudin-3 and claudin-4 was detected in 84, 64 and 52 cases respectively. Paradoxical cytoplasmic expression of claudin-1 was found in 33 cases, claudin-3 – in 50 cases, claudin-4 – in 66 cases; incidence in adenocarcinoma was statistically higher (p<0,05). Nuclear localization was observed relatively rare. Nuclear expression of claudin-1 was not detected. Nuclear expression of claudin-3 was detected in 2 cases of adenocarcinoma, reaction was diffuse and isolated. Nuclear expression of claudin-4 was detected in 10 cases from different types of premalignant lesions except hyperplastic polyps, reaction was focal and associated with cytoplasmic and membrane reactions. Conclusion: Nuclear expression of claudin-3 in colon adenocarcinoma and claudin-4 in premalignant lesions were detected for the first time. The nuclear translocation of claudins potentially may play a role in carcinogenesis. The possible mechanisms of this translocation are unknown.