The expression and prognosis of FOXO3a and Skp2 in human hepatocellular carcinoma

The forkhead box proteins (FOXO proteins) comprise a large family of functionally diverse transcription factors involved in cellular proliferation, transformation, differentiation and longevity. Recently, ubiquitination and proteasome degradation of FOXO3a have been reported. In this study, we investigated the role of FOXO3a and Skp2 in human hepatocellular carcinoma progression. Immunohistochemical analysis was performed on formalin-fixed paraffin sections of 91 specimens. Furthermore in vitro, western-blot analysis and protein stabilization studies were used to study the relationship between FOXO3a and Skp2. We found that the expression of FOXO3a was negatively related with Skp2 expression (r = -0.583; p < 0.05) and FOXO3a expression correlated significantly with histological grade (p = 0.000), cirrhosis (p = 0.015), and tumor size (p = 0.043) while Skp2 expression correlated significantly with histological grade (p = 0.000) and tumor size (p = 0.005). Kaplan-Meier analysis revealed that survival curves of low versus high expressers of FOXO3a and Skp2 showed a highly significant separation in HCC (p < 0.01). Our results suggested that FOXO3a and Skp2 may be considered to be important prognosis in human hepatocellular carcinoma. In vitro studies suggested that the degradation of FOXO3a may dependent on the expression of Skp2 in the proliferated Huh7 cells.