Annexin A2 expression and phosphorylation are up-regulated in hepatocellular carcinoma

Abstract

Annexins (ANXs) constitute a family of Ca2+ - dependent membrane-binding proteins; at least 20 of them have been described to date. Among these, Annexin A2 (ANXA2) has been revealed as a multi-functional protein in vitro. Its actual role in vivo, however, requires further investigation. We already reported that ANX-I (ANXA1) was up-regulated in hepatocellular carcinoma (HCC). The role of ANXA2 in various liver diseases including HCC remains obscure. In the present study, the protein and mRNA levels of ANXA2, as well as its localization, were determined for the normal human liver, chronic hepatitis liver, and non-tumorous and tumorous portions of HCC tissues. ANXA2 was rarely detected in either normal or chronic hepatitis liver tissues, whereas it was overexpressed at both the transcriptional and translational levels in tumorous and non-tumorous regions of HCC. In addition, in many cases, more ANXA2 was expressed in the tumorous portion than in the non-tumorous portion of HCC. The expression of ANXA2 was mainly localized in cancer cells, especially in poorly differentiated HCC. Furthermore, ANXA2 was tyrosine-phosphorylated in HCC. These data suggest that overexpression and tyrosine phosphorylation of ANXA2 play important roles in the malignant transformation process leading to HCC and are related to the histological grade of HCC.