Claudins as diagnostic and prognostic markers in gynecological cancer.

Claudins are the main protein components of tight junctions (TJs) which function as selective barriers by controlling paracellular diffusion, maintain cellular polarity and play a role in signal transduction. The expression pattern of the 24 known members of the claudin family proved to be organ and tissue specific. The up- or downregulation of individual claudins has been described, especially during carcinogenesis. A significant increase of claudins-1 and -7 was detected in premalignant cervical lesions and invasive cancer compared with normal cervical epithelia. Claudins-3 and -4 were elevated in endometrial cancer. Claudin-1 overexpression characterized type II (seropapillary) endometrial carcinoma, while claudin-2 was elevated in type I (endometrioid) carcinoma. Claudins-3 and -4 were highly expressed in serous ovarian carcinoma. The expression data on claudins in different premalignant and malignant alterations suggest that these proteins might serve as diagnostic and prognostic markers and might be targets for future therapy.