Abstract
Down-regulation of p27Kip1, which is well-known cell cycle inhibitor, is associated with advanced stage of cancer and poor patient survival. However, recent studies show that cytoplasmic localization of p27Kip1 would be more meaningful rather than expression levels in terms of cancer invasion. Jun activation domain-binding protein 1(Jab1) that is 5th component of COP9 signalosome complex involves in the translocation of p27Kip1 from nucleus to cytoplasm. But, relationship between Jab1 and p27Kip1 remains to be elucidated in papillary thyroid cancer (PTC). In this study, we performed the immunohistochemistry (IHC) for 29 specimens from patients who underwent surgical resection for PTC in Chung-Ang University Hospital to evaluate the expression levels and subcellular localization of Jab1 and p27Kip1. In addition, we analyzed the correlations between Ki67 (proliferative index) and those molecules. Expression levels of Jab 1 were much higher in tumor when comp! ared to normal thyroid tissues. Jab1 was more strongly stained in the periphery than center of tumors. Expression of p27Kip1 was not decreased in tumor and p27Kip1 was predominantly localized in the cytoplasm, especially in the periphery of tumor. The cytoplasmic localization of Jab1 positively correlated with that of p27(r = .928, P < .01), but not with Ki-67. Taken together, these findings suggest that Jab1 promotes the translocation of p27Kip1 from nucleus to cytoplasm, which is associated with the invasiveness of PTC.