Claudins are a family of proteins and most important component of the tight junction. They constitute paracellular barrier that controls the flow of molecules in the intercellular space of an epithelium. Though it seems that claudin should be down regulated in cancer cell, some claudins are, in fact,highly elevated in various human cancers including ovarian cancer. Whereas the functional significance of claudin overexpression in ovarian carcinoma is unclear, these proteins are important for migration, invasion, and survival of ovarian cancer cells. They clearly represent a general pathway in tumorigenesis, a novel marker for ovarian cancer and may become a target for therapy or diagnosis of this disease.

Keywords: Tight junction, occludin, claudin, ovarian cancer, Clostridium perfringens enterotoxin