Claudin-16/Paracellin-1, Cloning, Expression, and Its Role in Tight Junction Functions in Cancer and Endothelial Cells

Metastatic spread of cancer is the major reason for patient mortality in human breast cancer. We examined expression of claudin-16 in human breast cells and tissues to identify a possible link between expression and aggressiveness in cells and between claudin-16 levels and patient prognosis. Forced expression of claudin-16 in breast cancer cells resulted in a less aggressive phenotype and reduced in vivo tumour �volume. Claudin-16 expression was reduced in human breast cancer, particularly in patients with aggressive tumours and high mortality (Martin et al. J Cell Biochem 105:41–52,2008). This suggests that claudin-16 plays a role beyond that of an initial metastasis repressor in this cancer type.